CHAPTER 3 RESULTS AND DISCUSSIONshodhganga.inflibnet.ac.in/bitstream/10603/33583/8/08_chapter 3.pdf · sulphate attack, chloride attack and corrosion, respective tests were carried

46

CHAPTER 3

RESULTS AND DISCUSSION

The results obtained from the experimental investigations are

presented and discussed in this chapter. The effects of untreated and treated

tannery effluents, untreated and treated textile effluents on the important

properties of the concrete such as sulphate attack, chloride attack, corrosion,

chemical attack, alkali aggregate reaction, leachability of chloride,

leachability of sulphate, permeability, compressive strength, split tensile

strength, flexural strength of PCC beam, failure load of RCC beam and bond

strength are discussed in detail and compared with the concrete specimens

prepared using potable water for M20 grade of concrete.

3.1 EFFECT ON PROPERTIES OF CONCRETE PREPARED

USING TANNERY AND TEXTILE EFFLUENTS

To analyze the properties of the concrete such as compressive

strength, tensile strength, flexural strength, bond strength, permeability,

sulphate attack, chloride attack and corrosion, respective tests were carried

out. The untreated and treated effluents from the tanneries were collected on

11-04-2005 and the characteristics of the effluents were tested on the same

day and the results are tabulated in the Table 3.1. The untreated and treated

effluents from the textile processing units were collected on 12-04-2005 and

the characteristics of the effluents were tested on the same day and the results

are tabulated in the Table 3.1. The values of the properties of the untreated

47

and treated tannery effluents, untreated and treated textile effluents are taken

as the average of the samples collected at different places.

Table 3.1 Properties of the tannery (11-04-2005) and textile effluents

(12-04-2005)

SAMPLE PARAMETERS

pH Chloride Content (mg/l)

Total Dissolved Solids (mg/l)

Sulphate (mg/l)

Untreated Tannery Effluent

12.2 750 800 980

Treated Tannery Effluent

7.2 298 595 418

Untreated Textile Effluent

8.5 657 857 447

Treated Textile

Effluent 7.1 406 330 163

The concrete samples were prepared using potable water, untreated

and treated tannery effluents, untreated and treated textile effluents. The

concrete samples were then cured in the respective water and effluents for a

period of 28 days. After 28 days of curing, the important properties of the

concrete such as compressive strength, tensile strength, flexural strength,

bond strength, sulphate attack, chloride attack, corrosion studies, permeability

etc were meticulously studied and the results are presented in the Tables 3.2

and 3.3.

48

Table 3.2 Comparison of the strength properties of the concrete

Type of water used

Compr. Str. MPa

Tensile Str. MPa

Fl. Str. MPa

Bond Str. MPa

Bond Str. due to

corrosion

Perm.(K) x 10-7

cm/sec PW 25.46 2.30 3.50 1.45 0.43 7.90

UTT 26.34 2.36 3.75 1.50 0.47 8.20

TT 25.78 2.31 3.50 1.45 0.45 8.10

UTTE 26.10 2.35 3.50 1.47 0.46 8.10

TTE 25.60 2.31 3.50 1.46 0.43 8.00

Table 3.3 Comparison of the properties of the concrete

Type of water used

Sulphate Attack Chloride Attack Corrosion studies

Loss of Wt. in %

Compr. Str. MPa

Loss of Wt. in %

Compr. Str. MPa

Loss of Wt. in %

PW 0.68 22.78 1.92 23.50 6.30

UTT 5.43 16.34 8.30 15.80 8.82

TT 4.30 19.44 5.43 17.68 7.90

UTTE 5.28 17.30 8.12 15.34 8.60

TTE 3.97 19.90 5.04 17.51 7.32

To determine the properties of the concrete such as compressive

strength, tensile strength, flexural strength, bond strength, permeability,

sulphate attack, chloride attack and corrosion, respective tests were carried

out. From the analysis (Tables 3.2 and 3.3), it is observed that there are no

significant differences in the strength properties of the concrete such as

compressive strength, tensile strength, flexural strength and bond strength

whereas significant changes are observed in the form of loss of weight and

49

reduction in compressive strength of the concrete subjected to sulphate attack

and chloride attack. There is loss of weight of the reinforcement bar

embedded in the concrete due to induced corrosion. The initial setting time is

almost same (38 minutes to 47 minutes) for all the cement paste prepared

using potable water, tannery and textile effluents.

The loss of weight of the concrete, due to sulphate attack, prepared

using untreated and treated tannery effluents, untreated and treated textile

effluents are 4.75%, 3.62%, 4.6%, 3.29% respectively more than that of the

concrete prepared using the potable water. Similarly the reduction in the

compressive strength of the concrete, due to sulphate attack, prepared using

untreated and treated tannery effluents, untreated and treated textile effluents

are 28.27%, 14.66%, 24.05%, 12.64% respectively less than that of the

concrete prepared using potable water.

The loss of weight of the concrete, due to chloride attack, prepared


effluents are 6.38%, 3.51%, 6.2%, 3.12% respectively more than that of the

concrete prepared using potable water. Similarly the reduction in the

compressive strength of the concrete, due to chloride attack, prepared using


are 32.76%, 24.76%, 34.72%, 25.49% respectively less than that of the

concrete prepared using potable water.

The loss of weight of the reinforcement bar embedded in the

concrete, due to corrosion, prepared using untreated and treated tannery

effluents, untreated and treated textile effluents are 2.52%, 1.60%, 2.30%,

1.02% respectively higher than that of the concrete prepared using potable

water.

50

3.2 SELECTION OF ADMIXTURES

From the literature it is found that the fly ash enhances most of the

properties of the concrete such as reducing the permeability, improving the

structural strength in the longer run, offering good resistance to ingress of

sulphate ions and chloride ions (Gengying Li and Xiaohua Zhao 2003, Shetty

2003, Civjan et al 2005, Gopalan 2007, Malathy and Subramanian 2008). The

fly ash is cheap and it is available in large quantities as an industrial waste.

The utilization of waste materials such as fly ash in the preparation of the

concrete provides a satisfactory solution to some of the environmental

concerns such as problems associated with waste management (Ganesan

2007) and also fly ash reduces the cost of the concrete. Hence in this present

research fly ash is considered as an admixture to be added while preparing the

concrete to minimize the adverse effects on the concrete prepared using

tannery and textile effluents (Saraswathy et al 2003, Han Young Moon and

Kook Jae Shin 2004, Scott A Civjan et al 2005, Sarat Kumar Das and Yudhbir

2006, Sideris et al 2006). The admixtures are added as per IS 9103-1978

(1978).

It is observed that beyond 5% addition of fly ash, there is no

significant improvement in the concrete properties such as sulphate attack,

chloride attack and corrosion of the reinforcement bar embedded in the

concrete. In addition if more quantity (more than 10% or 15%) of fly ash is

added, the initial setting time is prolonged (Mustafa Sahmaran 2006) and

hence the addition of fly ash is limited to 5%.

The concrete samples were prepared using the different effluents

(detailed properties of the tannery and textile effluents collected on 22-09-

2005 and 23-09-2005 respectively are given in Table 3.4) with the addition of

5% fly ash (obtained from the Mettur thermal power plant and Neyveli

51

thermal power plant). After curing, the concrete samples were tested for the

concrete properties such as loss of weight and reduction in compressive

strength subjected to sulphate attack, chloride attack, corrosion (loss of weight

of the reinforcement bar embedded in the concrete) and permeability of the

concrete. The changes in the values of the concrete properties such as sulphate

attack, chloride attack and corrosion of the reinforcement bar embedded in the

concrete due to the addition of 5% of fly ash to the concrete are tabulated in

the Table 3.5.

Table 3.4 Properties of the tannery and textile effluents collected on

22-09-2005 and 23-09-2005 respectively

SAMPLE PARAMETERS



Sulphate (mg/l)

Untreated Tannery Effluent 12.0 734 812 963

Treated Tannery Effluent 7.4 307 574 403

Untreated Textile Effluent 8.2 651 841 403

Treated Textile Effluent

7.3 389 307 144

Table 3.5 Comparison of the properties of the concrete

Type of water used

Sulphate Attack Chloride Attack Corrosion Loss of

Wt. in % Compr.

Str. Loss of

Wt. in % Compr.

Str. Loss of

Wt. in % PW 0.54 23.78 1.85 23.83 6.15 UTT 5.02 17.20 8.14 15.97 8.56 TT 4.11 21.26 5.24 17.93 7.75

UTTE 4.96 21.47 8.42 15.84 8.52 TTE 4.08 22.67 4.92 17.86 7.20

52

There is only a little reduction in loss of weight of the concrete and

reduction in compressive strength of the concrete specimens subjected to

sulphate attack, chloride attack, and corrosion of the reinforcement bar

embedded in the concrete with the addition of 5% fly ash as admixture.

In order to improve the properties of 5% fly ash blended concrete

further, silica fume (Dotto et al 2004, Bektas et al 2005, Civjan et al 2005,

Maas et al 2007), rice husk ash (Ramachandran 1998, Isaia et al 2003, Sousa

Coutinho 2003, Bui et al 2005, Agarwal 2006), calcium nitrite (Jeknavorian

and Barry 1999, Omar et al 2003, Pedro Montes et al 2004, Civjan et al 2005,

Sideris and Savva 2005, Ann et al 2006), calcium nitrate (Harald Justnes and

Nygaard 1995, Omar et al 2003, Poongodi 2005), amino-alcohols

(Wombacher et al 2004), metakaolin (Sabir et al 2001, Tsivilis et al (2003),

Batis et al 2005, Nabil and Al-Akhras 2006) and commercial products

available in the market such as webac- 2061, webac 4170, concare etc are

considered as additional admixtures for preparing the concrete to completely

nullify the adverse effects using tannery and textile effluents.

The ternary blended concrete samples were prepared using the

different effluents (detailed properties of the tannery effluent and textile

effluents collected on 10-02-2006 and 13-02-2006 respectively are given in

Table 3.6) with the addition of 5% fly ash and other admixtures such as silica

fume, rice husk ash etc.

53


(13-02-2006)

SAMPLE PARAMETERS

pH Chloride Content mg/l)


Sulphate (mg/l)

Untreated Tannery Effluent 11.8 771 803 966

Treated Tannery Effluent 7.5 272 604 404

Untreated Textile Effluent 8.1 661 842 419

Treated Textile Effluent 7.5 376 298 169

The results of the addition of fly ash admixture along with the other

admixtures are tabulated in the Tables 3.7 to 3.18. Care is taken so that the

setting time of the concrete is not decreased with increase in the dosage of

corrosion inhibitor or sulphate resistant admixture or chloride resistant

admixture (Ann et al 2006).

Table 3.7 Sulphate attack on the concrete prepared using untreated

tannery effluent

Name of the admixtures added

Loss of weight (%) 28 days (1.0 %)

28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 0.23 0.21 0.20 0.19 0.18 FA + Calcium nitrite 0.31 0.29 0.23 0.21 0.17 FA + Calcium nitrate 0.14 0.12 0.09 0.10 0.10 FA + Metakaolin 0.45 0.41 0.38 0.32 0.28 FA + Silica fume 0.26 0.23 0.20 0.21 0.19 FA + Webac 2061 0.15 0.13 0.12 0.13 0.12 FA + Webac 4170 0.16 0.14 0.11 0.13 0.11 FA + Concare 0.14 0.12 0.11 0.08 0.08

54

Table 3.8 Sulphate attack on the concrete prepared using treated

tannery effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 0.16 0.14 0.12 0.12 0.13 FA + Calcium nitrite 0.19 0.16 0.15 0.15 0.15 FA + Calcium nitrate 0.09 0.08 0.06 0.06 0.06 FA + Metakaolin 0.38 0.35 0.35 0.30 0.26 FA + Silica fume 0.17 0.16 0.16 0.15 0.16 FA + Webac 2061 0.13 0.10 0.10 0.09 0.08 FA + Webac 4170 0.13 0.11 0.11 0.09 0.08 FA + Concare 0.10 0.09 0.08 0.07 0.07

Table 3.9 Sulphate attack on the concrete prepared using untreated

textile effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 0.19 0.17 0.16 0.16 0.15

FA + Calcium nitrite 0.19 0.18 0.18 0.18 0.17

FA + Calcium nitrate 0.13 0.10 0.08 0.08 0.07

FA + Metakaolin 0.36 0.34 0.34 0.31 0.30

FA + Silica fume 0.17 0.15 0.15 0.14 0.13

FA + Webac 2061 0.14 0.11 0.11 0.10 0.10

FA + Webac 4170 0.14 0.13 0.11 0.11 0.10

FA + Concare 0.13 0.11 0.09 0.09 0.09

55

Table 3.10 Sulphate attack on the concrete prepared using treated textile

effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 0.14 0.12 0.12 0.12 0.11



FA + Metakaolin 0.35 0.33 0.32 0.32 0.31

FA + Silica fume 0.16 0.14 0.12 0.12 0.11

FA + Webac 2061 0.11 0.10 0.10 0.09 0.09

FA + Webac 4170 0.12 0.11 0.11 0.10 0.09

FA + Concare 0.09 0.07 0.06 0.06 0.06

It is observed from the experimental results (Table 3.7), by the

addition of 5% fly ash and 2.5% concare along with the concrete (prepared

using untreated tannery effluent), the loss of weight of the concrete subjected

to sulphate attack is (0.08%) less than that of the concrete added with other

admixtures such as 2.0% calcium nitrate (0.09%), 3.0% rice husk ash

(0.18%), 3.0% calcium nitrite (0.17%), 3.0% metakaolin (0.28%), 3.0% silica

fume (0.19%) etc. When the concrete is prepared using treated tannery

effluent, the loss of weight of the concrete subjected to sulphate attack is

0.06% by adding 5% fly ash and 2.0% calcium nitrate and 0.07% by adding

5% fly ash and 2.5% concare which are less than that of the concrete added

with the admixtures such as 3.0% silica fume, 3.0% webac 2061, 3.0% webac

4170 etc (Table 3.8).

56

For the concrete prepared using untreated textile effluent, the loss

of weight of the concrete subjected to sulphate attack is 0.08% by adding 5%

fly ash and 2.0% calcium nitrate and 0.09% by adding 5% fly ash and 2.0%

concare which are less than that of the concrete added with the admixtures

such as 3.0% silica fume, 3.0% webac 2061, 3.0% webac 4170 etc

(Table 3.9). The loss of weight of the concrete subjected to sulphate attack is

0.06% by adding 5% fly ash and 2.0% calcium nitrate and 0.06% by adding

5% fly ash and 2.0% concare which are less than that of the concrete added

with the admixtures such as silica fume, webac 2061, webac 4170 etc for the

concrete prepared using treated textile effluent (Table 3.10.

Table 3.11 Chloride attack on the concrete prepared using untreated

tannery effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 0.51 0.48 0.47 0.47 0.46



FA + Metakaolin 0.49 0.47 0.45 0.45 0.44

FA + Silica fume 0.52 0.50 0.50 0.48 0.47

FA + Webac 2061 0.23 0.20 0.20 0.17 0.17

FA + Webac 4170 0.22 0.20 0.19 0.19 0.18

FA + Concare 0.32 0.30 0.27 0.26 0.26

57

Table 3.12 Chloride attack on the concrete prepared using treated

tannery effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 0.48 0.46 0.45 0.45 0.44



FA + Metakaolin 0.52 0.50 0.47 0.47 0.45

FA + Silica fume 0.50 0.49 0.48 0.46 0.43

FA + Webac 2061 0.29 0.28 0.27 0.27 0.25

FA + Webac 4170 0.31 0.29 0.26 0.25 0.21

FA + Concare 0.28 0.26 0.24 0.22 0.22

Table 3.13 Chloride attack on the concrete prepared using untreated

textile effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 0.47 0.45 0.43 0.43 0.42



FA + Metakaolin 0.49 0.48 0.44 0.42 0.41

FA + Silica fume 0.47 0.45 0.42 0.42 0.41

FA + Webac 2061 0.29 0.28 0.22 0.21 0.20

FA + Webac 4170 0.30 0.28 0.25 0.24 0.22

FA + Concare 0.24 0.22 0.19 0.18 0.18

58

Table 3.14 Chloride attack on the concrete prepared using treated

textile effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 0.44 0.42 0.40 0.39 0.36



FA + Metakaolin 0.46 0.44 0.42 0.42 0.41

FA + Silica fume 0.43 0.41 0.41 0.39 0.37

FA + Webac 2061 0.28 0.26 0.24 0.24 0.23

FA + Webac 4170 0.31 0.29 0.26 0.26 0.26

FA + Concare 0.22 0.20 0.17 0.17 0.17

From the experimental results (Table 3.11), it is observed that the

loss of weight of the concrete (prepared using untreated tannery effluent)

subjected to chloride attack is 0.17% by adding 5% fly ash and 2.5% webac

2061. The loss of weight of the concrete added with 5% fly ash and 2.5%

webac 2061 is less than that of the concrete added with 5% fly ash and other

admixtures such as 3.0% webac 4170 (0.18%), 2.5% concare (0.26%), 2.0%

calcium nitrate (0.32%) etc. The same trend is observed in the concrete

prepared using treated tannery effluent also (Table 3.12). For the concrete

added with 5% fly ash and 2.5% webac 2061 (prepared using untreated and

treated textile effluent), the loss of weight of the concrete subjected to

chloride attack is less than that of the concrete added with 5% fly ash and

other admixtures such as calcium nitrate, concare, rice husk ash, metakaolin,

silica fume etc (Tables 3.13 and 3.14).

59

Table 3.15 Corrosion studies on the concrete prepared using untreated

tannery effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 1.88 1.80 1.72 1.70 1.64



FA + Metakaolin 1.82 1.76 1.73 1.69 1.63

FA + Silica fume 1.83 1.80 1.74 1.72 1.70

FA + Webac 2061 1.59 1.56 1.54 1.51 1.51

FA + Webac 4170 1.69 1.61 1.57 1.53 1.50

FA + Concare 1.38 1.33 1.29 1.26 1.26

Table 3.16 Corrosion studies on the concrete prepared using treated

tannery effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 1.76 1.73 1.70 1.63 1.63



FA + Metakaolin 1.83 1.79 1.77 1.72 1.72

FA + Silica fume 1.82 1.80 1.80 1.78 1.74

FA + Webac 2061 1.55 1.54 1.50 1.49 1.49

FA + Webac 4170 1.68 1.66 1.64 1.61 1.58

FA + Concare 1.29 1.24 1.20 1.15 1.15

60

Table 3.17 Corrosion studies on the concrete prepared using untreated

textile effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 1.55 1.52 1.50 1.46 1.42



FA + Metakaolin 1.63 1.59 1.57 1.56 1.56

FA + Silica fume 1.65 1.61 1.60 1.58 1.58

FA + Webac 2061 1.49 1.47 1.47 1.44 1.42

FA + Webac 4170 1.60 1.58 1.56 1.55 1.51

FA + Concare 1.29 1.26 1.18 1.18 1.18

Table 3.18 Corrosion studies on the concrete prepared using treated

textile effluent



28 days (1.5 %)

28 days (2.0 %)

28 days (2.5 %)

28 days (3.0 %)

FA + Rice husk ash 1.49 1.47 1.46 1.46 1.41



FA + Metakaolin 1.53 1.49 1.46 1.46 1.44

FA + Silica fume 1.54 1.50 1.47 1.46 1.44

FA + Webac 2061 1.35 1.32 1.31 1.29 1.29

FA + Webac 4170 1.44 1.43 1.42 1.40 1.40

FA + Concare 1.23 1.19 1.14 1.14 1.14

61


concrete (prepared using untreated tannery effluent) added with 5% fly ash

and 2.5% concare (1.26%) is less than that of the concrete added with 5% fly

ash and other admixtures such as 3.0% calcium nitrate (1.43%), 3.0% rice

husk ash (1.64%), 3.0% calcium nitrite (1.81%), 3.0% metakaolin (1.63%) etc

(Table 3.15). It is evident from the Table 3.16, the loss of weight of the

reinforcement bar embedded in the concrete (prepared using treated tannery

effluent) added with 5% fly ash and 2.5% concare (1.15%) is less than that of

the concrete added with 5% fly ash and other admixtures such as 2.0%

calcium nitrate (1.28%), 2.5% rice husk ash (1.63%), 3.0% calcium nitrite

(1.76%), 2.5% metakaolin (1.72%), 2.5% webac 2061 (1.49%) etc

(Table 3.16).

It is observed from the experimental results (Table 3.17), the loss of

weight of the reinforcement bar embedded in the concrete (prepared using

untreated textile effluent) added with 5% fly ash and 2.0% concare (1.18%) is

less than that of the concrete added with 5% fly ash and other admixtures such

as 2.0% calcium nitrate (1.24%), 3.0% rice husk ash (1.42%), 2.5% calcium

nitrite (1.53%), 2.5% metakaolin (1.56%), 3.0% webac 2061 (1.42%), 3.0%

webac 4170 (1.51%) etc. The loss of weight of the reinforcement bar

embedded in the concrete (prepared using treated textile effluent) added with

5% fly ash and 2.5% concare (1.14%) is less than that of the concrete added

with 5% fly ash and other admixtures such as 3.0% calcium nitrate (1.18%),

3.0% rice husk ash (1.41%), 3.0% calcium nitrite (1.43%), 3.0% metakaolin

(1.44%), 2.5% webac 2061 (1.29%), 2.5% webac 4170 (1.40%) etc

(Table 3.18).

From the results, though the webac 2061 and webac 4170 reduced

the loss of weight of the concrete subjected to chloride attack, it has not

reduced the loss of weight of the concrete subjected to sulphate attack and the

62

loss of weight of the reinforcement bar embedded in the concrete subjected to

corrosion (Tables 3.11, 3.12, 3.13 and 3.14). Hence from the detailed

analysis, 5% fly ash and 2.5% concare or 5% fly ash and 2.0% calcium nitrate

are the better combination of admixture to reduce the adverse effects on the

concrete subjected to sulphate attack, chloride attack and corrosion of the

reinforcement bar embedded in the concrete prepared using tannery effluents.

Also 5% fly ash and 2.0 % concare or 5% fly ash and 2.0% calcium nitrate are

the better combination of admixture to reduce the adverse the effects due to

sulphate attack, chloride attack and corrosion of the reinforcement bar

embedded in the concrete prepared using textile effluents.

Based on the experimental results, the concrete blended with 5% fly

ash and 2.5% concare or 2.0% calcium nitrate are selected as the optimum

dosage for minimizing the adverse effects due to chemical attacks on the

concrete prepared using tannery effluents. The concrete blended with 5% fly

ash and 2.0% concare or 2.0% calcium nitrate is selected as the optimum

dosage for minimizing the adverse effects due to chemical attacks on the

concrete specimen cast using textile effluents. To prevent the corrosion of

reinforcement bar embedded in the concrete from the root level, a commercial

inhibitor named cempatch-R is coated on the steel reinforcement bar. The

properties of the concrete samples blended with 5% fly ash and 2.5% concare

prepared using effluents are almost equal to that of the concrete samples

blended with 5% fly ash and 2.0% concare using potable water.

The untreated and treated effluents from the tanneries were

collected on 17-03-2006 and the untreated and treated effluents from the

textile processing units were collected on 22-03-2006 and the characteristics

of the effluents were tested on the same day and the results are tabulated in

the Table 3.19.

63


(22-03-2006)

SAMPLE PARAMETERS



Sulphate (mg/l)

Untreated Tannery Effluent

11.8 719 832 932

Treated Tannery Effluent

7.6 290 587 441

Untreated Textile Effluent

8.0 644 838 432

Treated Textile

Effluent 7.6 410 314 149

The concrete samples were prepared and cured in the respective

effluent and water for a period of 28 days.

3.3 STUDIES ON THE PROPERTIES OF THE CONCRETE

(BLENDED WITH ADMIXTURES) PREPARED USING

EFFLUENTS FOR LONGER DURATION

The studies were extended for 2.5 years and the concrete samples

were tested after curing for 28 days, 180 days, 1 year, 2 years and 2.5 years.

The effects on the various properties of admixtures blended concrete such as

sulphate attack, chloride attack, corrosion studies, chemical attack, alkali

aggregate reaction, leachability of chloride, leachability of sulphate,

permeability, compressive strength, tensile strength, flexural strength (PCC

beams), failure load (RCC beams) and bond strength are discussed in detail.

64

3.3.1 Studies on the Sulphate Attack of the Concrete

The sulphate attack on the concrete is mainly due to chemical

reaction between calcium aluminate hydrate and sulphate ions. The result of

the chemical reaction is calcium sulphoaluminate hydrate, commonly referred

to as ettringite (3CaO.A12O3.3CaSO4.32H2O) which results in the reduction

of bond strength and internal disintegration of the concrete (Hime and Bryant

Mather 1999, Bing Tian and Cohen 2000, Vijayarangan 2006, Frank et al

2006). These solids (ettringite) have a very much higher volume up to 225%

of the concrete specimen. As a consequence, stresses are produced in the

concrete which may result in the breakdown of the cement paste and it ultimately

results in the breakdown of the concrete (Lee et al 2005a).

3.3.1.1 Loss of weight of the concrete

The loss of weight of the concrete, due to sulphate attack, prepared

using the potable water, the untreated and treated tannery effluents, the

untreated and treated textile effluents for various durations are tabulated in the

Table 3.20.

Table 3.20 Loss of weight of the concrete due to sulphate attack

prepared using the potable water, untreated and treated tannery effluents, untreated and treated textile effluents

Water used

Loss of weight of the concrete (%) 28 Days 180 days 1 Year 2 Years 2.5 years

PW 0.48 0.61 0.72 0.84 0.93 UTT 4.81 4.86 4.92 4.94 5.14 TT 3.52 3.69 3.79 3.86 3.99

UTTE 4.75 4.81 4.88 4.91 5.12 TTE 3.46 3.64 3.75 3.83 3.97

65

The loss of weight of the concrete prepared using the untreated and

treated tannery effluents, untreated and treated textile effluents after 28 days

are 4.33 %, 3.04%, 4.27% and 2.98% respectively. It is observed that the loss

of weight of the concrete prepared using the untreated and treated tannery

effluents, untreated and treated textile effluents is higher than that of the

concrete prepared using the potable water and this is due to the presence of

more amount of sulphate content in the untreated and treated tannery

effluents, untreated and treated textile effluents. There is 0.45%, 0.33%,

0.47%, 0.37%, 0.51% loss of weight of the concrete prepared using the

potable water, the untreated and treated tannery effluents, untreated and

treated textile effluents respectively after 2.5years and these are graphically

shown in the Figures 3.1 and 3.2.

There is more loss of weight of the concrete prepared using

untreated and treated tannery effluents than that of the concrete prepared

using untreated and treated textile effluents because there is more amount of

sulphate content in the tannery effluents. The loss of weight of the concrete is

because of the reaction between the concrete and sulphate ions and as a result

the volume of the concrete increases, stresses are produced and it results in

the breakdown of the cement paste and ultimately it results in the breakdown

of the concrete and so the weight of the concrete is reduced (Bing Tian and

Cohen 2000). The complete break down of the concrete is because of the

formation of the thaumasite which gradually deteriorates the internal structure

of concrete (Irassar 2009).

When 5% fly ash and concare (2.5% concare is added with the

concrete prepared using tannery effluent and 2.0% concare is added with the

concrete prepared using textile effluent) are added along with the concrete,

the loss of weight of the concrete prepared using potable water is 0.06% after

28 days and 0.12% after 2.5 years, the loss of weight of the concrete prepared

66

using untreated tannery effluent is 0.10% after 28 days and 0.14% after 2.5

years and the loss of weight of the concrete prepared using treated tannery

effluent is 0.07% after 28 days and 0.12% after 2.5 years. The loss of weight

of the concrete prepared using the untreated textile effluent is 0.09% after 28

days and 0.14% after 2.5 years and the loss of weight of the concrete prepared

using the treated textile effluent is 0.06% after 28 days and 0.12% after 2.5

years. The loss of weight of the concrete reduces from 0.48% to 0.06% for the

concrete prepared using the potable water, 4.81% to 0.10%, for untreated

tannery effluent, 3.52% to 0.07% for treated tannery effluent, 4.75% to 0.09%

for untreated textile effluent, 3.42% to 0.06% for treated textile effluent after

28 days. There is considerable reduction in the loss of weight of the concrete

subjected to sulphate attack by the addition of 5% fly ash and concare

admixture (2.5% for the concrete prepared using tannery effluent and 2.0%

for the concrete prepared using textile effluent) (Kilinckale 1997). By the

addition of 5% fly ash and concare (2.5% for the concrete prepared using

tannery effluent and 2.0% for the concrete prepared using textile effluent), the

loss of weight of the concrete is decreased (Nehdi and Hayek 2005). The

effect due to sulphate attack is almost minimized with the addition of the

admixtures, as the loss of weight of the concrete is concerned.

When 5% fly ash and 2.0% calcium nitrate are added with the

concrete, the loss of weight of the concrete prepared using potable water

decreases by 0.05% after 28 days and 0.10% after 2.5 years, the loss of weight

of the concrete prepared using the untreated tannery effluent is 0.09% after 28

days and 0.13% after 2.5 years and the loss of weight of the concrete prepared

using the treated tannery effluent is 0.06% after 28 days and 0.11% after 2.5

years. The loss of weight of the concrete prepared using the untreated textile

effluent is 0.08% after 28 days and 0.12% after 2.5 years and the loss of

weight of the concrete prepared using the treated textile effluent is 0.05%

after 28 days and 0.11% after 2.5 years.

67

The loss of weight of the concrete reduces from 0.48% to 0.05% for

the concrete prepared using potable water, 4.81% to 0.09%, for untreated




due to sulphate attack by the addition of 5% fly ash and 2.0% calcium nitrate

(Nader Ghafoori et al 2008). By the addition of 5% fly ash and 2.0% calcium

nitrate, the loss of weight of the concrete decreases or almost it becomes

negligible (Figures 3.1 and 3.2).

0.01

0.06

0.11

0.16

0 200 400 600 800 1000

Age of concrete (days)

Loss

of w

eigh

t (%

) PW with CUTT with CTT with CPW with CNUTT with CNTT with CN

Figure 3.1 Comparison of loss of weight of the concrete due to sulphate

attack prepared using the potable water, untreated and

treated tannery effluents (with admixtures only)

68

0.01

0.06

0.11

0.16

0 200 400 600 800 1000


Loss

of w

eigh

t (%

) PW with CUTTE with CTTE with CPW with CNUTTE with CNTTE with CN

Figure 3.2 Comparison of loss of weight of the concrete due to sulphate

attack prepared using the potable water, untreated and

treated textile effluents (with admixtures only)

3.3.1.2 Compressive strength of the concrete

It is evident from the Figures 3.3 and 3.4, the compressive strength

of the concrete prepared using the potable water is 23.74MPa after 28 days

and 26.36MPa after 2.5 years, the compressive strength of the concrete

prepared using the untreated tannery effluent is 18.59MPa after 28 days and

21.21MPa after 2.5 years and the compressive strength of the concrete

prepared using the treated tannery effluent is 20.32MPa after 28 days and

22.94MPa after 2.5 years. The compressive strength of the concrete prepared

using the untreated textile effluent is 18.36MPa after 28 days and 20.98MPa

after 2.5 years and the compressive strength of the concrete prepared using

the treated textile effluent is 20.09MPa after 28 days and 22.71MPa after

2.5 years.

69

The reduction in the compressive strength of the concrete prepared


effluents is 27.70%, 16.83%, 29.30% and 18.17% respectively higher than

that of the concrete prepared using the potable water after 28 days. There is

11.04%, 14.09%, 12.89%, 14.27% and 13.04% increase in the compressive of

the concrete prepared using potable water, untreated and treated tannery

effluent, untreated and treated textile effluent respectively after 2.5 years.

From the experimental results, between one year and 2.5 years there are only

1.89%, 2.36%, 2.18%, 2.39% and 2.21% increase in the compressive strength

of the concrete prepared using potable water, untreated and treated tannery

effluents, untreated and treated textile effluents respectively.

The compressive strength of the concrete prepared using untreated

and treated tannery effluents, untreated and treated textile effluents is less

than that of the concrete prepared using the potable water because of the

sulphate attack which weakens the bond strength of the concrete (Yilmaz et al

1997, Young et al 1999). The concrete gets disintegrated due to the sulphate

attack which is observed from the loss of weight of the concrete. Even though

there is only a marginal loss of weight of the concrete, there is considerable

reduction in the compressive strength of the concrete because the internal

structure of the concrete gets modified and disintegrated (Marchand et al

2002).




the compressive strength of the concrete prepared using the potable water is

25.02MPa after 28 days and 27.64MPa after 2.5 years, the compressive

strength of the concrete prepared using the untreated tannery effluent is

70

25.74MPa after 28 days and 28.37MPa after 2.5 years and the compressive

strength of the concrete prepared using the treated tannery effluent is

25.40MPa after 28 days and 28.02MPa after 2.5 years. The compressive

strength of the concrete prepared using the untreated textile effluent is


strength of the concrete prepared using the treated textile effluent is

25.17MPa after 28 days and 27.79MPa after 2.5 years.

By the addition of 5% fly ash and concare (2.5% concare is added

with the concrete prepared using tannery effluent and 2.0% concare is added

with the concrete prepared using textile effluent), the compressive strength of

the concrete increases by 5.39%, 38.46%, 25%, 38.94% and 25.29% using

potable water, untreated and treated tannery effluent, untreated and treated

textile effluent respectively after 28 days (Hanifi Binici and Orhan Aksogan

2006). The same trend is observed even after 2.5 years also. It is observed

from the experimental results, with the addition of the admixtures, the

compressive strength of the concrete prepared using tannery effluents and

textile effluents is almost equal to that of the compressive strength of the

concrete prepared using potable water. The decrease in the compressive

strength of the concrete subjected to sulphate attack is almost reduced with

the addition of the admixtures.

When 5% fly ash and 2.0% calcium nitrate are added along with the

concrete, the compressive strength of the concrete prepared using the potable

water is 25.47MPa after 28 days and 28.09MPa after 2.5 years, the

compressive strength of the concrete prepared using the untreated tannery

effluent is 26.19MPa after 28 days and 28.81MPa after 2.5 years and the

compressive strength of the concrete prepared using the treated tannery

71

effluent is 25.85MPa after 28 days and 28.47MPa after 2.5 years. The

compressive strength of the concrete prepared using the untreated textile

effluent is 25.96MPa after 28 days and 28.58MPa after 2.5 years and the

compressive strength of the concrete prepared using the treated textile effluent

is 25.62MPa after 28 days and 28.24MPa after 2.5 years. With the addition of

5% fly ash and 2.0% calcium nitrate, the compressive strength of the concrete

increases by 7.29%, 40.88%, 27.21%, 41.39% and 27.53% using the potable

water, the untreated and treated tannery effluents, untreated and treated textile

effluents respectively after 28 days. The same trend is observed after 2.5 years

also.

When fine aggregate, coarse aggregate, cement and admixture react

with water (hydration), silica gel and calcium hydroxide are formed. The

calcium hydroxide reacts with admixture and forms secondary gel which

hardens the concrete. The ingress of sulphate ions into the inner core of the

concrete is reduced and hence the effect of sulphate attack on the concrete is

minimized (Ezziane et al 2007). The formation of the ettringite is delayed

because of the addition of the admixture (Collepardi 2003). The increase in

the compressive strength of the concrete is because of the addition of

admixture which decreases the pore size of the concrete (Sanchez et al 2008).

The admixing fly ash (pozzolanic material) converts the leachable calcium

hydroxide into insoluble non-leachable cementitious product. In addition this

conversion is responsible for impermeability of the concrete. It is observed

from the experimental results, the compressive strength of the concrete

prepared using untreated and treated tannery effluents, untreated and treated

textile effluents is almost equal to that of the compressive strength of the

concrete prepared using the potable water with the addition of the admixtures.

The specimen subjected to sulphate attack is shown in Figure 3.5.

72

18

20

22

24

26

28

30

0 200 400 600 800 1000


Com

pres

sive

stre

ngth

(MPa

) PWUTTTTPW with CUTT with CTT with CPW with CNUTT with CNTT with CN

Figure 3.3 Comparison of the compressive strength of the concrete due

to sulphate attack using the potable water, untreated and

treated tannery effluents

18

20

22

24

26

28

30

0 200 400 600 800 1000


Com

pres

sive

stre

ngth

(MPa

) PWUTTETTEPW with CUTTE with CTTE with CPW with CNUTTE with CNTTE with CN

Figure 3.4 Comparison of the compressive strength of the concrete due

to sulphate attack using the potable water, untreated and

treated textile effluents

73

SPECIMEN SUBJECTED TO SULPHATE ATTACK

Figure 3.5 Specimen subjected to sulphate attack

By the addition of 5% fly ash and 2.0% calcium nitrate or 5% fly

ash and concare (2.5% concare is added with the concrete prepared using

tannery effluent and 2.0% concare is added with the concrete prepared using

textile effluent), the adverse effect due to sulphate attack on the concrete is

minimized. The sulphate attack is minimized by adding admixtures such as

fly ash with either concare or calcium nitrate in required proportions (Khatri

et al 1997, Vu et al 2001, Bryant Mather 2004). From the results, it can be

concluded that by using ternary blended concrete, the sulphate resistance of

the concrete can be improved (Ghrici et al 2007).

3.3.2 Studies on the Chloride Attack of the Concrete

The chloride attack on the concrete is particularly important

because it primarily induces the corrosion of reinforcement bar embedded in

the concrete (Glass and Buenfeld 1998, Luping Tang 1999). It is observed

that more number of failure and collapse of structures are due to corrosion of

reinforcement bar embedded in the concrete. The concrete subjected to

74

chloride attack is characterized by efflorescence and persistent dampness in

the concrete structure.


The loss of weight of the concrete subjected to chloride attack

prepared using potable water, untreated and treated tannery effluents,

untreated and treated textile effluents are tabulated in the Table 3.21.

Table 3.21 Loss of weight of the concrete due to chloride attack prepared

using potable water, untreated and treated tannery effluents,

untreated and treated textile effluents

Water used Loss of weight of the concrete (%)

28 Days 180 days 1 Year 2 Years 2.5 years

PW 1.70 0.92 0.87 0.78 0.74

UTT 7.91 7.10 6.96 6.88 6.80

TT 4.61 3.79 3.70 3.62 3.57

UTTE 7.29 6.79 6.72 6.66 6.61

TTE 4.06 3.58 3.49 3.43 3.38

The loss of weight of the concrete prepared using untreated and

treated tannery effluents, untreated and treated textile effluents are 6.21%,

2.91%, 5.59% and 2.36% respectively higher than that of the concrete

specimen prepared using potable water after 28 days (Poornima 2006). There

is decrease of 0.96%, 1.11%, 1.04%, 0.68%, 0.68% loss of weight of the

concrete prepared using potable water, untreated and treated tannery effluents,

untreated and treated textile effluents respectively after 2.5 years. It is

observed that there is more loss of weight of the concrete prepared using

75

tannery effluents than that of the concrete prepared using textile effluents

because there is more amount of chloride content in the tannery effluents. The

loss of weight of the concrete prepared using potable water is almost similar

to that of the concrete prepared using tannery and textile effluents after 2.5

years, because initially there is more loss of weight of the concrete due to the

chloride attack.

The loss of weight of the concrete is because of the deterioration of

the concrete which is often characterized by the expansion of the concrete

exposed to chloride particles (Poornima 2006). The deterioration of the

concrete is due to the penetration of chloride ions or compounds through the

cover of concrete by the process of diffusion. In addition the concrete

subjected to chloride attack has shown efflorescence and persistent dampness

on the surface of the concrete. The loss of weight of the concrete decreases

with passage of time i.e after 28 days, the loss of weight of the concrete is

1.70% but after 2.5 years it is only 0.74% for potable water and the same

phenomena is observed for all the concrete specimens cast using different

waters. This may be due to the reduction in the permeability factor of the

concrete. It is observed that the loss of weight of the concrete prepared using


is higher than that of the concrete prepared using potable water and this is due

to presence of chloride in the untreated and treated tannery effluents,

untreated and treated textile effluents. The Figure 3.10 shows the specimens

subjected to chloride attack.



concrete prepared using textile effluent) are added while preparing the

concrete, it is evident from the Figures 3.6 and 3.7, the loss of weight of the

concrete prepared using potable water is 0.21% after 28 days and 0.12% after

76

2.5 years, the loss of weight of the concrete prepared using untreated tannery


weight of the concrete prepared using treated tannery effluent is 0.22% after

28 days and 0.13% after 2.5 years. The loss of weight of the concrete

prepared using untreated textile effluent is 0.18% after 28 days and 0.11%

after 2.5 years and the loss of weight of the concrete prepared using treated

textile effluent is 0.17% after 28 days and 0.10% after 2.5 years.


the concrete prepared using potable water, 7.91% to 0.26% for untreated



28 days of curing. There is considerable reduction in the loss of weight of the

concrete due to chloride attack by the addition of 5% fly ash and concare

(2.5% concare is added with the concrete prepared using tannery effluent and

2.0% concare is added with the concrete prepared using textile effluent)

admixture. By the addition of 5% fly ash and concare (2.5% concare is added


with the concrete prepared using textile effluent), the loss of weight of the

concrete decreases considerably or almost it becomes negligible (Jin Zuquan

et al 2007).

When 5% fly ash and 2% calcium nitrate are added with the

concrete, the loss of weight of the concrete prepared using potable water is

0.29% after 28 days and 0.12% after 2.5 years, the loss of weight of the

concrete prepared using untreated tannery effluent is 0.32% after 28 days and

0.15% after 2.5 years and the loss of weight of the concrete prepared using

treated tannery effluent is 0.31% after 28 days and 0.13% after 2.5 years. The

loss of weight of the concrete prepared using untreated textile effluent is

0.27% after 28 days test and 0.18% after 2.5 years and the loss of weight of

77

the concrete prepared using treated textile effluent is 0.27% after 28 days and

0.16% after 2.5 years.






due to chloride attack by the addition of 5% fly ash and 2% calcium nitrate.

By the addition of 5% fly ash and 2% calcium nitrate, the loss of weight of

the concrete decreases or almost it becomes negligible. The effect due to

chloride attack on the concrete is almost minimized, as the loss of weight of

the concrete is concerned with the addition of admixtures.

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 200 400 600 800 1000


Loss

of w

eigh

t (%

) PW with CUTT with CTT with CPW with CNUTT with CNTT with CN

Figure 3.6 Comparison of loss of weight of the concrete due to chloride

attack prepared using potable water, untreated and treated

tannery effluents (admixtures only)

78

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 200 400 600 800 1000


Loss

of w

eigh

t (%

) PW with CUTTE with CTTE with CPW with CNUTTE with CNTTE with CN

Figure 3.7 Comparison of loss of weight of the concrete due to chloride

attack prepared using potable water, untreated and treated

textile effluents (admixtures only)


The compressive strength of the concrete prepared using potable

water is 23.24MPa after 28 days and 26.13MPa after 2.5 years. The

compressive strength of the concrete prepared using untreated tannery effluent

is 16.09MPa after 28 days and 18.98MPa after 2.5 years and the compressive

strength of the concrete prepared using treated tannery effluent is 18.75MPa

after 28 days and 21.64MPa after 2.5 years. The compressive strength of the

concrete prepared using untreated textile effluent is 15.86MPa after 28 days

and 18.75MPa after 2.5 years and the compressive strength of the concrete

prepared using treated textile effluent is 18.52MPa after 28 days and

21.41MPa after 2.5 years. The Figures 3.8 and 3.9 show the variation of the

compressive strength of the concrete due to chloride attack with and without

the addition of admixtures.

79

The decrease in the compressive strength of the concrete prepared


effluents are 44.44%, 23.95%, 46.53% and 25.49% respectively more than

that of the concrete prepared using potable water after 28 days. There is

12.44%, 17.96%, 15.41%, 18.22% and 15.60% increase in the compressive

strength of the concrete prepared using potable water, untreated and treated

tannery effluents, untreated and treated textile effluents respectively after 2.5

years. It is observed that between one year and 2.5 years there are only 2.43%,

3.38%, 2.95%, 3.42% and 2.98% increase in the compressive of the concrete


untreated and treated textile effluents respectively.

The compressive strength of the concrete goes on increasing with

the increase in age of the concrete. The compressive strength of the concrete


textile effluents is less than that of the concrete prepared using potable water

due to chloride attack which weakens the bond strength of concrete. The

concrete gets disintegrated due to the chloride attack and it is evident from the

loss of weight of the concrete. Hence it can be concluded that the compressive

strength of the concrete increases with reduction in loss of weight of the

concrete.




the compressive strength of the concrete prepared using potable water is


strength of the concrete prepared using untreated tannery effluent is



80





27.56MPa after 2.5 years.




the concrete increases by 5.51%, 56.87%, 32.80%, 57.69% and 33.21% using

potable water, untreated and treated tannery effluents, untreated and treated

textile effluents respectively after 28 days. Almost the same trend is observed

after 2.5 years also. It is observed from the experimental results that the

compressive strength of the concrete specimens prepared using untreated and

treated tannery effluents, untreated and treated textile effluents are almost

equal to that of the compressive strength of the concrete prepared using

potable water. The decrease in the compressive strength of the concrete due to

chloride attack is almost reduced.

When 5% fly ash and 2.0% calcium nitrate are added with the

concrete, the compressive strength of the concrete prepared using potable










81

With the addition of 5% fly ash and 2% calcium nitrate, the compressive strength of the concrete increases by 7.44%, 59.66%, 35.20%, 60.53% and 35.64% using potable water, untreated and treated tannery effluent, untreated and treated textile effluent respectively after 28 days (Sarat Kumar Das and Yudhbir 2006). Almost the same trend is observed after 2.5 years also (Figures 3.8 and 3.9). The hardening and strength development of the blended concrete is faster than that of the conventional concrete because the blended admixture modifies the pore structure of the concrete (Yong Xin Li et al 2006). The formation of the secondary gel improves the denseness of the concrete formation and as a result the ingress of the chloride ions is prevented. It is observed from the experimental results that the compressive strength of the concrete specimen cast using tannery and textile effluents is almost equal to that of the compressive strength of the concrete specimen cast using potable water with the addition of 5% fly ash and concare (2.5% concare is added with the concrete prepared using tannery effluent and 2.0% concare is added with the concrete prepared using textile effluent) or 5% fly ash and 2% calcium nitrate.

16

18

20

22

24

26

28

30

0 200 400 600 800 1000


Com

pres

sive

stre

ngth

(MPa


Figure 3.8 Comparison of compressive strength of the concrete due to chloride attack prepared using potable water, untreated and treated tannery effluents

82

15

17

19

21

23

25

27

29

0 200 400 600 800 1000


Com

pres

sive

stre

ngth

(MPa


Figure 3.9 Comparison of compressive strength of the concrete due to

chloride attack prepared using potable water, untreated and


SPECIMEN SUBJECTED TO CHLORIDE ATTACK

Figure 3.10 Specimen subjected to chloride attack

The pozzolanic action is responsible for the impermeability of the

concrete and in turn it reduces the adverse effects on the concrete due to

chloride attack, in terms of loss of weight of the concrete and reduction in the

compressive strength of the concrete (Gruber et al 2001). Hence by the

83

addition of 5% fly ash and 2.0% calcium nitrate or 5% fly ash and concare


2.0% concare is added with the concrete prepared using textile effluent), the

adverse effect due to chloride attack on the concrete is reduced.

3.3.3 Studies on the Corrosion of the Concrete The corrosion is defined as a process of gradual wearing away of a

metal (reinforced bar embedded in the concrete) due to chemical and

electrochemical reaction by its surroundings. Due to high alkality of the

concrete a protective oxide film is present on the surface of the steel

reinforcement bar. This protective layer can be lost because of the presence of

chloride in the presence of water and oxygen (chemical reaction). In practice,

the action of chloride ions, on the reinforcement bar embedded in the

concrete, in inducing the corrosion is the more serious problem than any other

problems (Ormellese et al 2006, Mohd Firdows et al 2007).

In an electrochemical process, when there is a difference in

electrical potential in the steel, one part becomes anode and the other part

becomes cathode and connected by an electrolyte in the form of pore water in

the hardened cement paste. The positively charged ferrous ions (Fe++) at the

anode pass into solution while negatively charged free electrons (e-) pass

through the steel into cathode where they are absorbed by the constituents of

the electrolyte and combine with water and oxygen to form hydroxyl ions

((OH)-) (Olivier Poupard et al 2004). These travel through the electrolyte and

combine with the ferrous ions to form ferric hydroxide which is converted by

further oxidation in to rust (Tamizheselvi and Samuel Knight 2007). The

other important causes of corrosion of reinforcement bar embedded in the

concrete are due to excessive water cement ratio, permeability of the concrete,

pH of water, presence of salts, quality of water used and atmospheric

conditions (Woo-Yong Jung et al 2003, Erdogdua et al 2004). The corrosion

84

of reinforced bar embedded in the concrete is observed in the form of

deterioration and loss of weight of the material (reinforced bar) (Li 2003).


concrete prepared using potable water is 5.36% after 28 days and 6.87% after

2.5 years, the loss of weight of the reinforcement bar embedded in the

concrete prepared using untreated tannery effluent is about 7.82% after 28

days and 9.74% after 2.5 years and the loss of weight of the reinforcement bar

embedded in the concrete prepared using treated tannery effluent is about

7.54% after 28 days and 9.49% after 2.5 years. The loss of weight of the

reinforcement bar embedded in the concrete prepared using untreated textile

effluent is about 7.92% after 28 days and 8.83% after 2.5 years and the loss of

weight of the reinforcement bar embedded in the concrete prepared using

treated textile effluent is about 7.54% after 28 days and 8.61% after 2.5 years.

The loss of weight of the reinforcement bar embedded in the concrete is

because of the reduction in cross sectional area (As a result of chemical or

electrochemical reaction, the reinforced bar is converted into oxide) of the

reinforced bar embedded in the concrete (Kapilesh Bhargava et al 2005,

Jieying Zhang and Zoubir Lounis 2006).


concrete prepared using untreated and treated tannery effluents, untreated and

treated textile effluents is 2.46%, 2.18%, 2.56% and 2.18% respectively and is

more than that of the loss of weight of reinforcement bar embedded in the

concrete prepared using potable water after 28 days. It is observed from the

experimental results that the corrosion phenomena is more noticed in the

concrete prepared using untreated and treated tannery effluents, untreated and

treated textile effluents than that of the concrete prepared using potable water.

The same trend is observed for the entire 2.5 years as shown in the Figure

3.11 and 3.12. There is an increase of 1.51%, 1.92%, 1.95% 0.91% and 1.07%

85

loss of weight of the reinforcement bar embedded in the concrete prepared

using potable water, untreated and treated tannery effluents, untreated and

treated textile effluents between 28 days and 2.5 years. The loss of weight of

the reinforcement bar embedded in the concrete prepared using untreated

tannery effluent and untreated textile effluent is 0.28 % and 0.38% more than

that of the reinforcement bar embedded in the concrete prepared using treated

tannery effluent and treated textile effluent.



concrete prepared using textile effluent) is added with the concrete, the loss of


potable water is 1.12% after 28 days and 2.14% after 2.5 years, the loss of


untreated tannery effluent is about 1.26% after 28 days and 2.21% after 2.5

years and the loss of weight of the reinforcement bar embedded in the

concrete treated tannery effluent is about 1.15% after 28 days and 2.16% after

2.5 years. The loss of weight of the reinforcement bar embedded in the

concrete prepared using untreated textile effluent is 1.18% after 28 days and

2.17% after 2.5 years and the loss of weight of the reinforcement bar

embedded in the concrete prepared using treated textile effluent is about

1.14% after 28 days and 2.15% after 2.5 years.



untreated and treated textile effluents decreases by 4.24%, 6.56%, 6.39%,

6.74% and 6.40% respectively after 28 days. This is because of the

modification of the pore structure of the concrete and reduction in

permeability of the concrete due to the addition of the admixture (Gruber et al

2001). The movements of water and chloride ions are reduced inside the

86

concrete and as a result the corrosion of reinforced bar embedded in the

concrete is also reduced. When 5% fly ash and concare (2.5% concare is

added with the concrete prepared using tannery effluent and 2.0% concare is

added with the concrete prepared using textile effluent) are added with the

concrete, the loss of weight of the reinforcement bar embedded in the concrete

specimen is considerably decreased.


concrete, the loss of weight of the reinforcement bar embedded in the concrete

prepared using potable water is 1.16% after 28 days and 2.21% after 2.5

years, the loss of weight of the reinforcement bar embedded in the concrete

prepared using untreated tannery effluent is 1.46% after 28 days and 2.58%

after 2.5 years and the loss of weight of the reinforcement bar embedded in

the concrete prepared using treated tannery effluent is 1.28% after 28 days

and 2.35% after 2.5 years. The loss of weight of the reinforcement bar

embedded in the concrete prepared using untreated textile effluent is 1.24%

after 28 days and 2.28% after 2.5 years and the loss of weight of the

reinforcement bar embedded in the concrete prepared using treated textile

effluent is 1.19% after 28 days and 2.24% after 2.5 years.



untreated and treated textile effluents decreases by 4.20%, 6.36%, 6.26%,

6.68% and 6.35% respectively after 28 days. The effects of the corrosion of

the reinforcement bar embedded in the concrete are graphically shown in

Figures 3.11 and 3.12. It is observed that the initiation of the corrosion of the

reinforcement bar embedded in the concrete is delayed due to the addition of

the admixtures and also the rate of the corrosion is reduced (Gaidis 2004,

Wombacher et al 2004). There is considerable reduction in the loss of weight

87

of the reinforcement bar embedded in the concrete due to the addition of 5%

fly ash and 2% calcium nitrate which enhances the properties of the concrete.

1

2

3

4

5

6

7

8

9

10

0 200 400 600 800 1000


Loss

of w

eigh

t (%

)

PWUTTTTPW with CUTT with CTT with CPW with CNUTT with CNTT with CN

Figure 3.11 Comparison of loss of weight of the reinforcement bar

embedded in the concrete prepared using potable water,

untreated and treated tannery effluents

1

2

3

4

5

6

7

8

9

0 200 400 600 800 1000


Loss

of w

eigh

t (%

)

PWUTTETTEPW with CUTTE with CTTE with CPW with CNUTTE with CNTTE with CN

Figure 3.12 Comparison of loss of weight of the reinforcement bar

embedded in the concrete prepared using potable water,


88

When the reinforcement bar embedded in the concrete is coated

with chempatch-R, the loss of weight of the reinforcement bar embedded in

the concrete prepared using potable water is 0.24% after 28 days and 0.25%

after 2.5 years, the loss of weight of the reinforcement bar embedded in the

concrete prepared using untreated tannery effluent is about 0.26% after 28

days and 0.28% after 2.5 years and the loss of weight of the reinforcement bar

embedded in the concrete prepared using treated tannery effluent is about

0.26% after 28 days and 0.27% after 2.5 years. The loss of weight of the

reinforcement bar embedded in the concrete prepared using untreated textile



treated textile effluent is 0.24% after 28 days and 0.25% after 2.5 years

(Bryant Mather 2004).


concrete prepared using potable water, untreated and treated tannery effluent,

untreated and treated textile effluent decreases by 5.12%, 7.56%, 7.28%,

7.68% and 7.30% respectively after 28 days. After 2.5 years also the same

trend is observed. When the reinforcement is coated with chempatch-R, the

decrease in weight of reinforcement bar reduces almost to 0.27% of the total

corrosion without adding any admixture. This is due to the fact that when the

steel bar is coated with chempatch-R, a thin layer is formed around the steel

and the steel is protected from invasion of water or chloride ion present in the

concrete.

This experiment is carried out by coating the reinforcement with

chempatch-R and adding the admixtures such as 5% fly ash and concare


2.0% concare is added with the concrete prepared using textile effluent) and

5% fly ash and 2% calcium nitrate to the concrete.

89

When 5% fly ash and concare (2.5% concare is added with the concrete prepared using tannery effluent and 2.0% concare is added with the concrete prepared using textile effluent) are added with the concrete and the embedded reinforcement bar is coated with chempatch-R, the loss of weight of the reinforcement bar embedded in the concrete prepared using potable water is 0.01% after 28 days and 0.02% after 2.5 years, the loss of weight of the reinforcement bar embedded in the concrete prepared using untreated tannery effluent is about 0.01% after 28 days and 0.03% after 2.5 years and the loss of weight of the reinforcement bar embedded in the concrete prepared using treated tannery effluent is about 0.01% after 28 days and 0.03% after 2.5 years. The loss of weight of the reinforcement bar embedded in the concrete prepared using untreated textile effluent is 0.01% after 28 days and 0.03% after 2.5 years and the loss of weight of the reinforcement bar embedded in the concrete prepared using treated textile effluent is 0.01% after 28 days and 0.02% after 2.5 years. When 5% fly ash and 2% calcium nitrate are added with the concrete and the reinforcement bar is coated with chempatch-R, the loss of weight of the reinforcement bar embedded in the concrete prepared using potable water is 0.01% after 28 days and 0.02% after 2.5 years, the loss of weight of the reinforcement bar embedded in the concrete prepared using untreated tannery effluent is 0.01% after 28 days and 0.04% after 2.5 years and the loss of weight of the reinforcement bar embedded in the concrete prepared using treated tannery effluent is 0.01% after 28 days and 0.03% after 2.5 years. The loss of weight of the reinforcement bar embedded in the concrete prepared using untreated textile effluent is 0.01% after 28 days and 0.03% after 2.5 years and the loss of weight of the reinforcement bar embedded in the concrete prepared using treated textile effluent is 0.01% after 28 days and 0.02% after 2.5 years. From the experimental results graphically shown in Figures 3.13 and 3.14, it is observed that the corrosion of the reinforcement bar embedded in the concrete is reduced to less than 0.05% by coating the embedded reinforcement bar with chempatch-R.

90

0

0.05

0.1

0.15

0.2

0.25

0.3

0 200 400 600 800 1000

Age of concrete in (days)

Loss

of w

eigh

t (%

)


Figure 3.13 Comparison of loss of weight of chempatch-R coated

reinforcement bar embedded in the concrete prepared using

potable water, untreated and treated tannery effluents

0

0.05

0.1

0.15

0.2

0.25

0.3

0 200 400 600 800 1000


Loss

of w

eigh

t (%

)


Figure 3.14 Comparison of loss of weight of chempatch-R coated

reinforcement bar embedded in the concrete prepared using

potable water, untreated and treated textile effluents

91

The Figures 3.15 and 3.16 shows the corrosion test in progress and

Figure 3.17 shows the concrete specimen subjected to corrosion.

CORROSION TEST SETUPCORROSION TEST SETUP

Figure 3.15 Corrosion test in progress

Figure 3.16 Observing measurements in corrosion studies

92

Figure 3.17 Specimen subjected to corrosion



concrete prepared using textile effluent), 5% fly ash and 2% calcium nitrate

are added to the concrete, embedded with the reinforcement bar coated with

chempatch-R, the decrease in weight of the reinforcement bar almost

decreases by less than 0.05% which is almost equal to zero. It is observed that

the loss of weight of the reinforcement bar embedded in the concrete, due to

corrosion, is totally minimized. It is concluded that the corrosion of steel

reinforcement bar embedded in the concrete prepared using tannery and

textile effluents are almost minimized with the addition of admixtures and

reinforcement bar coated with chempatch-R. The additional precautionary

steps such as providing proper cover depth, controlled water cement ratio and

avoiding congested reinforcement etc can also be adopted and practiced to

prevent and control the corrosion of the reinforcement bar embedded in the

concrete while prepared using industrial effluents (Byung Hwan Oh and

Seung Yup Jang 2007, Khatri and Sirivivatnanon 2004).

93

3.3.3.1 Corrosion studies of the concrete (without acceleration of

corrosion)

This experiment is carried out to study the corrosion properties of

the reinforcement bar embedded in the concrete without inducing corrosion

by any artificial means. The loss of weight of the reinforcement bar embedded

in the concrete is 0% after 28 days and 0% after 2.5 years using potable water,

untreated and treated tannery effluents, untreated and treated textile effluents.

From the experimental results, it is observed that in normal day to day

conditions there is no loss of weight of the reinforcement bar embedded in the

concrete due to corrosion even when the concrete is prepared using tannery

and textile effluents. It is concluded that there is loss of weight of the

reinforcement bar embedded in the concrete due to corrosion over a period of

2.5 years.

3.3.4 Studies on the Chemical Attack of the Concrete

Chemical attack generally occurs when calcium hydroxide present

in the concrete is vigorously attacked. The acidic solutions both mineral (such

as sulphuric, hydrochloric, nitric, and phosphoric chemicals) and organic

(such as lactic, acetic, formic, tannic chemicals) are the most aggressive

agents inducing chemical attack on the concrete. The chemical attack on the

concrete will not cause deterioration in the interior of the concrete structure

without the cement paste on the outer portion being completely destroyed.

The rate of penetration is inversely proportional to the quantity of chemical

neutralizing material, such as the calcium hydroxide, cement gel (C-S-H gel)

and limestone aggregates. In practice, the degree of chemical attack on the

concrete goes on increasing with an increase in acidity of the concrete. The

chemical attack on the concrete occurs at values of pH below 6.5, a pH of less

than 4.5 leading to severe chemical attack. Indirectly due to chemical attack,

94

when pH of the concrete reduces below 6.5, it gives rise to the corrosion of

the reinforcement bar embedded in the concrete (Tamer El Maaddawy and

Khaled Soudki 2007). The rate of chemical attack also depends on the ability

of hydrogen ions to be diffused through the cement gel (C-S-H) after calcium

hydroxide (Ca (OH)2) has been dissolved and leached out of the concrete.


From the Figures 3.18 and 3.19, the loss of weight of the concrete

prepared using potable water is 2.27% after 28 days and 1.75% after 2.5

years, the loss of weight of the concrete prepared using untreated tannery


weight of the concrete prepared using treated tannery effluent is 3.28% after

28 days and 2.77% after 2.5 years. The loss of weight of the concrete

prepared using untreated textile effluent is 3.18% after 28 days and 2.68%

after 2.5 years and the loss of weight of the concrete prepared using treated

textile effluent is 3.14% after 28 days and 2.65% after 2.5 years.

The loss of weight of the concrete specimens cast using untreated

and treated tannery effluents, untreated and treated textile effluents are 1.03

%, 1.01%, 0.91% and 0.87% respectively more than that of the concrete

specimens cast using potable water after 28 days. After 2.5 years, the loss of

weight of the concrete samples prepared using untreated and treated tannery

effluents, untreated and treated textile effluents is 1.05 %, 1.02%, 0.93% and

0.90% respectively more than that of the concrete specimens prepared using

potable water. Almost the same trend is observed after 28 days and 2.5 years.

The loss of weight of the concrete decreases with the passage of

time i.e after 28 days, the decrease in loss of weight of the concrete is 2.27%

but after 2.5 years it is only 1.75% for potable water and this condition is

95

same for all the concrete specimens prepared using tannery and textile

effluents (Bassuoni and Nehdi 2007). This may be due to the reduction in

permeability factor of the concrete.



concrete prepared using textile effluent) are added with the concrete, the loss

of weight of the concrete prepared using potable water is 2.23% after 28 days

and 1.73% after 2.5 years, the loss of weight of the concrete prepared using

untreated tannery effluent is 2.94% after 28 days and 2.62% after 2.5 years

and the loss of weight of the concrete prepared using treated tannery effluent

is 2.89% after 28 days and 2.58% after 2.5 years. The loss of weight of the

concrete prepared using untreated textile effluent is 2.85% after 28 days and


treated textile effluent is 2.84% after 28 days and 2.49% after 2.5 years.

The loss of weight of the concrete specimen reduces from 2.27% to

2.23% for the concrete prepared using potable water, 3.30% to 2.94%, for

untreated tannery effluent, 3.28% to 2.89% for treated tannery effluent, 3.18%

to 2.85% for untreated textile effluent, 3.14% to 2.84% for treated textile

effluent after 28 days. There is considerable reduction in the loss of weight of

the concrete due to chemical attack by the addition of fly ash and concare. By

the addition of 5% fly ash and concare (2.5% concare is added with the


concrete prepared using textile effluent) admixture, the loss of weight of the

concrete decreases or almost it becomes negligible (Gopalan 2007).


concrete, the loss of weight of the concrete prepared using potable water is

2.24% after 28 days and 1.75% after 2.5 years, the loss of weight of the

96

concrete prepared using untreated tannery effluent is 2.95% after 28 days and


treated tannery effluent is 2.90% after 28 days and 2.60% after 2.5 years. The

loss of weight of the concrete prepared using untreated textile effluent is

2.86% after 28 days and 2.52% after 2.5 years and the loss of weight of the

concrete prepared using treated textile effluent is 2.85% after 28 days and

2.51% after 2.5 years.




for untreated textile effluent and 3.14% to 2.85% for treated textile effluent

after 28 days. There is only a little reduction in the loss of weight of the

concrete due to chemical attack by the addition of 5% fly ash and 2% calcium

nitrate.

1

1.5

2

2.5

3

3.5

0 200 400 600 800 1000


Loss

of w

eigh

t (%

)


Figure 3.18 Comparison of loss of weight of the concrete due to chemical

attack on the concrete prepared using potable water,

untreated and treated tannery effluents

97

1

1.5

2

2.5

3

3.5

0 200 400 600 800 1000


Loss

of w

eigh

t (%

)


Figure 3.19 Comparison of loss of weight of the concrete due to chemical

attack on the concrete prepared using potable water,












20.25MPa after 2.5 years. The compressive strength of the concrete subjected

to chemical attack is graphically shown in the Figures 3.20 and 3.21.

98

It is observed from the experimental results that there is significant

decrease in the compressive strength of the concrete prepared using potable

water, untreated and treated tannery effluents, untreated and treated textile

effluents. The reduction in the compressive strength of the concrete is almost

same for all the concrete samples prepared irrespective of the water used. This

holds good for both 28 days and 2.5 years duration. But the required

compressive strength of the concrete i.e 20MPa is not obtained due to the

chemical attack. The chemical attack weakens the bond strength of the

concrete. As a result, the concrete gets disintegrated and it is observed from

the loss of weight.







concrete specimen prepared using untreated textile effluent is 18.23MPa after

28 days and 21.12MPa after 2.5 years and the compressive strength of the

concrete prepared using treated textile effluent is 17.89MPa after 28 days and





the concrete specimen increases by 3.08%, 2.96%, 3.01%, 2.99% and 3.05%


untreated and treated textile effluents respectively after 28 days. Almost the

99

same trend is observed after 2.5 years also. It is observed from the

experimental results that the compressive strength of the concrete specimens

cast using untreated and treated tannery effluents, untreated and treated textile

effluents is almost equal to the compressive strength of the concrete specimen

cast using potable water.











By the addition of 5% fly ash and 2% calcium nitrate, the

compressive strength of the concrete increases by 3.60%, 3.46%, 3.52%,

3.50% and 3.57% using potable water, untreated and treated tannery effluents,

untreated and treated textile effluents respectively after 28 days. Almost the

same trend is observed after 2.5 years also. It is observed from the

experimental results that the compressive strength of the concrete specimen

prepared using tannery and textile effluents is almost equal to the compressive

strength of the concrete specimen cast using potable water.

100

17

18

19

20

21

22

0 200 400 600 800 1000


Com

pres

sive

stre

ngth

(MPa



chemical attack on the concrete prepared using potable

water, untreated and treated tannery effluents

17

18

19

20

21

22

0 200 400 600 800 1000


Com

pres

sive

stre

ngth

(MPa



chemical attack on the concrete prepared using potable

water, untreated and treated textile effluents

101



with the concrete prepared using textile effluent) or 5% fly ash and 2%

calcium nitrate with the concrete, the reduction in loss of weight of the

concrete and increase in the compressive strength of the concrete is due to the

fact that the pH values of the concrete were improved and the alkalinity of the

concrete also got improved. It is concluded that there is no effect in terms of

loss of weight of the concrete and reduction in the compressive strength of the

concrete due to chemical attack on the concrete prepared using tannery and

textile effluents.

3.3.5 Studies on the Alkali Aggregate Reaction on the Concrete

Alkali aggregate reaction of the concrete is the reaction between

certain silicious constituents in the aggregate and the alkali sodium and

potassium hydroxide which are released during the hydration of cement. A

gelatinous product is formed which imbibes pore fluid and in doing so, the

concrete gets expanded, inducing an internal stress within the concrete. It is

observed that many failures of concrete structures such as pavement,

abutments, sea structures etc., are due to the alkali aggregate reaction (Rui

Miguel Ferreira 2004). The reaction may be due to availability of moisture,

salts present in water and alkali content in cement or aggregate etc.

The expansion of the mortar bars cast using potable water is 0.00%

after 28 days, 0.38% after 180 days, 0.46% after 1 year, 0.52% after 2 years

and 0.52% after 2.5 years, the expansion of the mortar bars cast using

untreated tannery water is about 0.00% after 28 days, 0.41% after 180 days,

0.50% after 1 year, 0.54% after 2 years and 0.54% after 2.5 years and the

102

expansion of the mortar bars cast using treated tannery water is about 0.00%


and 0.54% after 2.5 years. The expansion of the mortar bars cast using

untreated textile water is about 0.00% after 28 days, 0.40% after 180 days,

0.49% after 1 years, 0.53% after 2 years and 0.53% after 2.5 years and the

expansion of the mortar bars cast using treated textile water is about 0.00%


and 0.52% after 2.5 years. The effects are graphically represented in

Figures 3.22 and 3.23.

There is no expansion of the concrete due to alkali aggregate reaction after 28 days for all types of the water. There is 36.84 %, 31.71 %, 35.00 %, 32.50 % and 33.33 % increase in expansion of the mortar bar due to alkali aggregate reaction between 180 days and 2.5 years using potable water, untreated and treated tannery effluents, untreated and treated textile effluents respectively. There is 7.89 % and 5.26 % higher expansion in the concrete prepared using untreated and treated tannery effluents than that of the potable water. There is 5.26 % and 2.63 % higher expansion in the concrete prepared using untreated and treated textile effluents than that of the potable water. As far as the alkali aggregate reaction of the concrete is considered, there is no significant difference among the concrete specimens cast using potable water, untreated and treated tannery effluents, untreated and treated textile effluents. Even when the admixtures such as 5% fly ash and concare (2.5% concare is added with the concrete prepared using tannery effluent and 2.0% concare is added with the concrete prepared using textile effluent) or 5% fly ash and 2% calcium nitrate are added with the concrete, there is no significant reduction in expansion of the concrete specimens prepared using potable water or tannery and textile effluents (Figures 3.22 and 3.23) and hence it is not discussed in detail.

103

0

0.1

0.2

0.3

0.4

0.5

0.6

0 200 400 600 800 1000


Expa

nsio

n (%

)


Figure 3.22 Comparison of expansion of mortar bar due to alkali

aggregate reaction of the concrete prepared using potable

water, untreated and treated tannery effluents

0

0.1

0.2

0.3

0.4

0.5

0.6

0 200 400 600 800 1000


Expa

nsio

n (%

)


Figure 3.23 Comparison of expansion of mortar bar due to alkali

aggregate reaction of the concrete prepared using potable

water, untreated and treated textile effluents

104

3.3.6 Studies on the Leachability of Sulphate from the Concrete

The leachability of the sulphate from the concrete is an important property for safeguarding the environment. When there is any rain after the construction or any water flow on the concrete, there may be a possibility of leaching out of the sulphate ions from the concrete. The sulphate present in the water immersed with the concrete samples made using potable, untreated and treated tannery effluents, untreated and treated textile effluents are 187mg/l after 28 days and 150.26mg/l after 2.5 years, 199.45mg/l after 28 days and 179.15mg/l after 2.5 years, 190.16mg/l after 28 days and 168.30mg/l after 2.5 years, 196.05mg/l after 28 days and 175.33mg/l after 2.5 years and 189.76mg/l after 28 days and 164.48mg/l after 2.5 years respectively (Figures 3.24 and 3.25). The sulphate present in the water immersed with the concrete samples made using untreated and treated tannery effluents, untreated and treated textile effluents are 6.66%, 1.69%, 4.84% and 1.48% respectively which are higher than that of the concrete made using potable water. This is due to the excess sulphate content present in the various effluents. When 5% fly ash and concare (2.5% concare is added with the concrete prepared using tannery effluent and 2.0% concare is added with the concrete prepared using textile effluent) are added with the concrete, the sulphate present in the water immersed with concrete samples made using potable, untreated and treated tannery effluents, untreated and treated textile effluents are 171.58mg/l after 28 days and 142.40mg/l after 2.5 years, 179.81mg/l after 28 days and 158.25mg/l after 2.5 years, 174.26mg/l after 28 days and 154.58mg/l after 2.5 years, 176.41mg/l after 28 days and 154.43mg/l after 2.5 years and 172.86mg/l after 28 days and 153.76mg/l after 2.5 years respectively.

105

By the addition of 5% fly ash and concare (2.5% concare is added with the concrete prepared using tannery effluent and 2.0% concare is added with the concrete prepared using textile effluent), the sulphate present in the water immersed with concrete samples made using potable water, untreated and treated tannery effluents, untreated and treated textile effluents are reduced by 8.99%, 10.92%, 9.12%, 11.13% and 9.78% respectively after 28 days. The sulphate present in the water immersed with concrete samples made using potable water, untreated tannery effluent, treated tannery effluent, untreated textile effluent and treated textile effluent are reduced by 5.52%, 13.21%, 8.88%, 13.53% and 6.97% respectively after 2.5 years. There is more amount of sulphate ion reduction in 2.5 years duration than that of 28 days. When 5% fly ash and 2% calcium nitrate are added with the concrete, the sulphate present in the water immersed with concrete samples made using potable, untreated and treated tannery effluents, untreated and treated textile effluents are 170.25mg/l after 28 days and 141.92mg/l after 2.5 years, 179.14mg/l after 28 days and 157.12mg/l after 2.5 years, 173.16mg/l after 28 days and 153.88mg/l after 2.5 years, 175.74mg/l after 28 days and 153.30mg/l after 2.5 years and 172.76mg/l after 28 days and 152.06mg/l after 2.5 years respectively. By the addition of 5% fly ash and 2.0% calcium nitrate, the sulphate present in the water immersed with concrete samples made using potable water, untreated and treated tannery effluents, untreated and treated textile effluents are reduced by 9.84%, 11.34%, 9.82%, 11.56% and 9.84% respectively after 28 days. The sulphate present in the water immersed with concrete samples made using potable water, untreated tannery effluent, treated tannery effluent, untreated textile effluent and treated textile effluent are reduced by 5.88%, 14.02%, 9.37%, 14.37% and 8.17% respectively after 2.5 years. There is more sulphate reduction after 2.5 years than after 28 days of testing which are graphically shown in Figures 3.24 and 3.25.

106

140

150

160

170

180

190

200

0 200 400 600 800 1000


Leac

habi

lity

(mg/

l) PWUTTTTPW with CUTT with CTT with CPW with CNUTT with CNTT with CN

Figure 3.24 Comparison of leachability of the sulphate from the

concrete prepared using potable water, untreated and

treated tannery effluents

140

150

160

170

180

190

200

0 200 400 600 800 1000


Leac

habi

lity

(mg/

l) PWUTTETTEPW with CUTTE with CTTE with CPW with CNUTTE with CNTTE with CN

Figure 3.25 Comparison of leachability of the sulphate from the

concrete prepared using potable water, untreated and


107

The reduction in sulphate content is due to the modification of pore

structure of the concrete. The sulphate content decreases after 2.5 years due to

the hardening property of the concrete. The concrete becomes impermeable

with duration of time. It is observed from the experimental results that there is

considerable reduction in sulphate content by the addition of 5% fly ash and

concare (2.5% concare is added with the concrete prepared using tannery

effluent and 2.0% concare is added with the concrete prepared using textile

effluent) with the concrete or 5% fly ash and 2% calcium nitrate with the

concrete.

3.3.7 Studies on the Leachability of Chloride from the Concrete

The leachability of chloride from the concrete is an important

property for safe guarding the surrounding environment. When there is rain

after construction or any water flow over the concrete, there may be a

possibility of leaching of chloride particles from the concrete.

The chloride present in the water immersed with the concrete

samples made using potable, untreated and treated tannery effluents, untreated

and treated textile effluents are 82.34mg/l after 28 days and 75.24mg/l after

2.5 years, 101.14mg/l after 28 days and 97.10mg/l after 2.5 years, 91.28mg/l

after 28 days and 87.54mg/l after 2.5 years, 97.74mg/l after 28 days and

93.28mg/l after 2.5 years and 87.88mg/l after 28 days and 83.72mg/l after 2.5

years respectively.

The chloride content present in the water immersed with the

concrete samples made using untreated and treated tannery effluents,

untreated and treated textile effluents are 22.83%, 10.86%, 18.70% and 6.73%

respectively higher than that of the concrete made using potable water which

108

are graphically represented in Figures 3.26 and 3.27. This is due to the excess

chloride content present in the various effluents.



concrete prepared using textile effluent) are added with the concrete, the

chloride present in the water immersed with concrete samples made using

potable, untreated and treated tannery effluents, untreated and treated textile

effluents are 78.84mg/l after 28 days and 70.22mg/l after 2.5 years,

101.14mg/l after 28 days and 97.10mg/l after 2.5 years, 87.42mg/l after 28

days and 83.68mg/l after 2.5 years, 93.00mg/l after 28 days and 88.28mg/l

after 2.5 years and 84.02mg/l after 28 days and 79.86mg/l after 2.5 years

respectively.



with the concrete prepared using textile effluent), the chloride present in the

water immersed with concrete samples made using potable water, untreated

and treated tannery effluents, untreated and treated textile effluents are

reduced by 4.44%, 4.92%, 4.42%, 5.10% and 4.59% respectively after 28

days. The chloride present in the water immersed with the concrete samples

made using potable water, untreated and treated tannery effluent, untreated

and treated textile effluent are reduced by 7.15%, 5.43%, 4.61%, 5.66% and

4.83%respectively after 2.5 years. There is more chloride reduction in 2.5

years than that of 28 days.


concrete, the chloride present in the water immersed with concrete samples

made using potable, untreated and treated tannery effluents, untreated and

109

treated textile effluents are 76.20mg/l after 28 days and 68.64mg/l after 2.5

years, 95.36mg/l after 28 days and 92.22mg/l after 2.5 years, 86.32mg/l after

28 days and 81.90mg/l after 2.5 years, 91.96mg/l after 28 days and 88.40mg/l

after 2.5 years and 82.92mg/l after 28 days and 78.08mg/l after 2.5 years

respectively.

By the addition of 5% fly ash and 2% calcium nitrate, the chloride

present in the water immersed with concrete samples made using potable

water, untreated and treated tannery effluents, untreated and treated textile

effluents are reduced by 8.06%, 6.06%, 5.75%, 6.29% and 5.98% respectively

after 28 days. The chloride present in the water immersed with concrete

samples made using potable water, untreated and treated tannery effluents,

untreated and treated textile effluents are reduced by 9.62%, 5.29%, 6.89%,

5.52% and 7.22% respectively after 2.5 years. There is more chloride

reduction after 2.5 years than 28 days.

50

60

70

80

90

100

110

0 200 400 600 800 1000


Leac

habi

lity

(mg/

l) PWUTTTTPW with CUTT with CTT with CPW with CNUTT with CNTT with CN

Figure 3.26 Comparison of leachability of the chloride from the concrete

prepared using potable water, untreated and treated

tannery effluents

110

50

60

70

80

90

100

110

0 200 400 600 800 1000


Leac

habi

lity

(mg/

l) PWUTTETTEPW with CUTTE with CTTE with CPW with CNUTTE with CNTTE with CN

Figure 3.27 Comparison of leachability of the chloride from the concrete

prepared using potable water, untreated and treated textile

effluents

The reduction in chloride content is due to the modification of pore

structure of the concrete. The chloride content decreases after 2.5 years due to

the hardening property of the concrete. The concrete becomes impermeable

with increase in the age of the concrete. It is observed from the experimental

results that there is considerable reduction in chloride content by the addition

of 5% fly ash and concare (2.5% concare is added with the concrete prepared

using tannery effluent and 2.0% concare is added with the concrete prepared

using textile effluent) with the concrete or 5% fly ash and 2% calcium nitrate

with the concrete.

3.3.8 Studies on the Permeability of the Concrete

Permeability of concrete is the property by which water can

penetrate into the pores of the concrete. The penetration of weathering agents

111

along with the water into the concrete may lead to corrosion of reinforcement

bar embedded in the concrete which in turn weakens the structures. The

penetration of materials along with the solution adversely affects the

durability aspects of the concrete. The factors affecting the permeability of the

concrete are formation of micro cracks in the transition zones, cracks

generated through higher structural stresses, cracks formed due to corrosion

of the reinforcement bar embedded in the concrete, atmospheric moisture,

quality and purity of water used for making concrete etc. The permeability of

the concrete usually determines the rate of deterioration of the concrete

(Ganesh et al 2007).

The permeability of the concrete prepared using potable water is

7.70 x 10-7 cm/sec after 28 days and 5.40 x 10-7 cm/sec after 2.5 years, the

permeability of the concrete prepared using untreated tannery effluent is 7.80

x 10-7 cm/sec after 28 days and 6.00 x 10-7 cm/sec after 2.5 years and the

permeability of the concrete prepared using treated tannery effluent is 7.70 x

10-7 cm/sec after 28 days and 5.90 x 10-7 cm/sec after 2.5 years. The

permeability of the concrete prepared using untreated textile effluent is 7.70 x

10-7 cm/sec after 28 days and 5.90 x 10-7 cm/sec after 2.5 years and the

permeability of concrete prepared using treated textile effluent is 7.60 x 10-7

cm/sec after 28 days and 5.80 x 10-7 cm/sec after 2.5 years. The effects of the

permeability of the concrete prepared using different waters with the addition

of various admixtures are graphically shown in Figures 3.28 and 3.29.

The permeability of the concrete prepared using untreated and

treated tannery effluents, untreated and treated textile effluents is 1.30 %, 0.00

%, 0.00 % and 0.00 % higher than that of the concrete prepared using potable

water after 28 days of testing. The permeability of the concrete prepared using

untreated tannery effluent and untreated textile effluent is 1.30 % and 1.32 %

112

higher than that of the concrete prepared using treated tannery and treated

textile effluent after 28 days of curing. The permeability of the concrete

significantly decreases with the increase in age of the concrete. The

permeability of the concrete prepared using potable water, untreated and

treated tannery effluents, untreated and treated textile effluents decreases by

42.59 %, 30.00 %, 30.51 %, 30.51 % and 31.03 % after 2.5 years. This is

because of the hardening of the concrete due to increase in the age of the

concrete.

From the discussion, it is clear that the permeability of the concrete

goes on decreasing with increase in age of the concrete (El-Dieb 2006). This

phenomenon is common for all the concrete specimens cast using any type of

water such as potable water, untreated and treated tannery effluents, untreated

and treated textile effluents.



with the concrete prepared using textile effluent) admixture, the permeability

of the concrete prepared using potable water is 7.50 x 10-7 cm/sec after 28

days and 5.00 x 10-7 cm/sec after 2.5 years, the permeability of the concrete

prepared using untreated tannery effluent is 7.60 x 10-7 cm/sec after 28 days

and 5.60 x 10-7 cm/sec after 2.5 years and the permeability of the concrete

prepared using treated tannery effluent is 7.50 x 10-7 cm/sec after 28 days and

5.50 x 10-7 cm/sec after 2.5 years. The permeability of the concrete prepared

using untreated textile effluent is 7.50 x 10-7 cm/sec after 28 days and 5.50 x

10-7 cm/sec after 2.5 years and the permeability of the concrete prepared using

treated textile effluent is 7.40 x 10-7 cm/sec after 28 days and 5.40 x 10-7

cm/sec after 2.5 years.

113

Due to the addition of 5% fly ash and concare (2.5% concare is


added with the concrete prepared using textile effluent), there is 2.67 %

decrease in permeability of the concrete specimen cast using potable water,

2.63 % decrease in permeability of the concrete prepared using untreated

tannery effluent and 2.67 % decrease in permeability of the concrete prepared

using treated tannery effluent after 28 days of testing. The decrease in the

permeability of the concrete is 8.00 %, 7.14 % and 7.27 % for potable water,

untreated tannery effluent and treated tannery effluent after 2.5 years. For the

remaining test duration of 180 days, 1 year and 2 years, the permeability of

the concrete goes on decreasing gradually. There is 2.63 % to 8.00 % decrease

in the permeability of the concrete due to the addition of fly ash and concare

admixture (Dinakar et al 2008). There is 2.70 % decrease in the permeability

of the concrete specimen prepared using potable water, 2.67 % decrease in the

permeability of the concrete prepared using untreated textile effluent and 2.70

% decrease in the permeability of the concrete prepared using treated textile

effluent after 28 days of curing. The decrease in the permeability of the

concrete is 8.16 %, 7.27 % and 7.41 % for potable water, untreated textile

effluent and treated textile effluent after 2.5 years. There is 2.63 % to 8.16 %

decrease in the permeability of the concrete due to addition of fly ash and

concare admixture for the concrete prepared using untreated and treated

tannery effluents, untreated and treated textile effluents. This is because of the

addition of the admixtures (fly ash and concare) which modify the pore

structure of the concrete (Khatri et al 1997).

When 5% fly ash and 2% calcium nitrate are added, the

permeability of the concrete prepared using potable water is 7.40 x 10-7

cm/sec after 28 days and 4.90 x 10-7 cm/sec after 2.5 years, the permeability

of the concrete prepared using untreated tannery effluent is 7.50 x 10-7 cm/sec

114

after 28 days and 5.50 x 10-7 cm/sec after 2.5 years and the permeability of the

concrete prepared using treated tannery effluent is 7.40 x 10-7 cm/sec after 28

days and 5.40 x 10-7 cm/sec after 2.5 years. The permeability of the concrete

prepared using untreated textile effluent is 7.40 x 10-7 cm/sec after 28 days

and 5.40 x 10-7 cm/sec after 2.5 years and the permeability of the concrete

prepared using treated textile effluent is 7.30 x 10-7 cm/sec after 28 days and

5.30 x 10-7 cm/sec after 2.5 years.

By the addition of 5% fly ash and 2% calcium nitrate admixture,

there is 4.05 % decrease in the permeability of the concrete specimen cast

using potable water, 4.00 % decrease in the permeability of the concrete

specimen cast using untreated tannery effluent and 4.05 % decrease in the

permeability of the concrete specimen cast using treated tannery effluent after

28 days of testing. The decrease in the permeability of the concrete is 10.20

%, 9.09 % and 9.26 % for potable water, untreated tannery effluent and

treated tannery effluent after 2.5 years. There is 4.00 % to 10.20 % decrease

in the permeability of the concrete due to addition of 5% fly ash and 2%

calcium nitrate. There is 4.11 % decrease in the permeability of the concrete

specimen cast using potable water, 4.05 % decrease in the permeability of the

concrete cast using untreated textile effluent and 4.11 % decrease in the

permeability of the concrete prepared using treated textile effluent after 28

days of testing. The decrease in the permeability of the concrete is 10.42 %,

9.26 % and 9.43 % for potable water, untreated textile effluent and treated

textile effluent after 2.5 years. There is 4.05 % to 10.42 % decrease in the

permeability of the concrete due to addition of 5% fly ash and 2% calcium

nitrate admixture at the early days of testing.

115

4.5

5

5.5

6

6.5

7

7.5

8

0 200 400 600 800 1000


Co-e

ff o

f per

m. (

10-7

cm

/sec


Figure 3.28 Comparison of the permeability of the concrete prepared

using potable water, untreated and treated tannery effluents

4.5

5

5.5

6

6.5

7

7.5

8

0 200 400 600 800 1000


Co-e

ff o

f per

m. (

10-7

cm

/sec


Figure 3.29 Comparison of the permeability of the concrete prepared

using potable water, untreated and treated textile effluents

116

The Figure 3.30 show the permeability test in progress

Figure 3.30 Permeability test in progress

It is observed that the permeability of the concrete is reduced by the

addition of the admixture (Ghosh et al 2002 a). This is because the admixture

reduces the permeability of concrete due to its fineness and formation of

C-S-H gel and considerable reduction in the volume of the large pores of

concrete. Another fact is that with the addition of admixture, the water cement

ratio also gets reduced considerably. The reduction in the permeability of the

concrete is because of the better interlocking of bond among the coarse

aggregate, fine aggregate and cement paste (Malathy 2004). It is because of

the better interlocking of the bond among the coarse aggregate, fine aggregate

and cement paste, the other properties of the concrete such as compressive

strength, tensile strength, bond strength of the concrete etc are improved. In

addition, the pozzolanic reaction and pore size refinement mechanisms due to

117

the addition of the admixture are responsible for decrease in the permeability

of the concrete (Ha Won Song and Seung Jun Kwon 2007). It can be

concluded that the permeability is not a constraining factor for preparing the

concrete, blended with fly ash either with concare (2.5% concare is added


with the concrete prepared using textile effluent) or 2% calcium nitrate

admixture, prepared using the tannery and textile effluents.

3.3.9 Studies on the Compressive Strength of the Concrete

The compressive strength of the hardened cement is the most

important of all the properties of the concrete. It is used as a qualitative

measure for other properties of the hardened concrete. Almost in all structural

applications the concrete is employed primarily to resist the compressive

stresses.











The compressive strength of the concrete prepared using untreated

and treated tannery effluents, untreated and treated textile effluents is 3.34 %,

118

1.88%, 2.38 % and 0.92 % respectively higher than that of the concrete

prepared using potable water after 28 days of testing because of the chemicals

and salts present in the untreated and treated tannery effluents, untreated and

treated textile effluents (Saricimen et al 2004). The compressive strength of

the concrete samples prepared using untreated tannery and untreated textile

effluent is 1.44 % and 1.45 % higher than that of the concrete samples

prepared using treated tannery effluent and treated treated textile effluent after

28 days of testing which are shown graphically in the Figures 3.31 and 3.32.

The increase in the compressive strength of the concrete between 28 days and

1 year prepared using potable water, untreated and treated tannery effluents,

untreated and treated textile effluents is 9.66 %, 11.17 %, 11.29 %, 9.07 %

and 9.57 % respectively. The increase in the compressive strength of the

concrete between 1 year and 2.5 years prepared using potable water, untreated

and treated tannery effluents, untreated and treated textile effluents is 2.36 %,

2.34 %, 2.32 %, 2.36 % and 2.34 % respectively. The compressive strength of

the concrete increases in the range of 9.07 % to 11.29 % up to one year and

there after the increment in the compressive strength of the concrete becomes

negligible (approximately 2.36 %).




compressive strength of the concrete prepared using potable water is


strength of the concrete prepared using untreated tannery effluent is



after 28 days and it is 28.53MPa after 2.5 years. The compressive strength of

the concrete prepared using untreated textile effluent is 25.73MPa after 28

days and 28.66MPa after 2.5 years, the compressive strength of the concrete

119

prepared using treated textile effluent is 25.46MPa after 28 days and it is


With the addition of 5% fly ash and concare (2.5% concare is added


with the concrete prepared using textile effluent) there is 5.56 % increase in

the compressive strength of the concrete prepared using potable water, 5.05 %

increase in the compressive strength of the concrete prepared using untreated

tannery effluent and 5.46 % increase in the compressive strength of the

concrete prepared using treated tannery effluent after 28 days of testing

(Krishnaswami et al 2007). The increase in the compressive strength of the

concrete is 4.99 %, 4.82 % and 4.54 % for potable water, untreated and

treated tannery effluent after 2.5 years respectively. For the remaining test

duration of 180 days, 1 year and 2 years, the compressive strength of the

concrete is increasing gradually (Figures 3.31 and 3.32). There is 4.54 % to

5.56 % increase in the compressive strength of the concrete due to the

addition of 5% fly ash and concare admixture (2.5% concare is added with the


concrete prepared using textile effluent).

There is 4.97 % increase in the compressive strength of the

concrete prepared using potable water, 5.10 % increase in the compressive

strength of the concrete prepared using untreated textile effluent and 5.51 %

increase in the compressive strength of the concrete prepared using treated

textile effluent after 28 days of testing. The increase in the compressive

strength of the concrete is 4.13 %, 4.86 % and 4.58 % for potable water,

untreated and treated textile effluents after 2.5 years respectively. For the

remaining test duration of 180 days, 1 year and 2 years, the compressive

strength of the concrete is increasing gradually. The reason for the increase in

the compressive strength of the concrete due to the addition admixture is that

the cement particles inside the concrete are packed closer and denser than

120

earlier. Due to the reaction between fly ash and concare with the calcium

hydroxide present in the concrete more gel is formed which ultimately

produces C-S-H gel (Malathy 2004). The added admixture (fly ash and

concare) sometimes also acts as the filler material inside the concrete and

increases the compressive strength of the concrete (Oner and Akyuz 2007).

There is 4.97% to 5.51% increase in the compressive strength of the concrete

due to the addition of 5% fly ash and concare (2.5% concare is added with the


concrete prepared using textile effluent) admixture for untreated and treated

tannery effluents, untreated and treated textile effluents (Eshmaiel Ganjian

and Homayoon Sadeghi Pouya 2005).


concrete, the compressive strength of the concrete prepared using potable



is 26.40MPa after 28 days and 29.33MPa after 2.5 years, the compressive




and 29.10MPa after 2.5 years, the compressive strength of the concrete



By the addition of 5% fly ash and 2% calcium nitrate with the

concrete, there is 7.44 % increase in the compressive strength of the concrete

prepared using potable water, 6.83 % increase in the compressive strength of

the concrete prepared using untreated tannery effluent and 6.89 % increase in

the compressive strength of the concrete prepared using treated tannery

121

effluent after 28 days of testing (Aggoun et al 2008). The increase in the

compressive strength of the concrete is 6.29 %, 6.42 % and 6.19 % for potable

water, untreated and treated tannery effluent after 2.5 years respectively. For

the remaining test duration of 180 days, 1 year and 2 years, the compressive

strength of the concrete is increasing gradually as shown graphically in the

Figures 3.31 and 3.32. There is 6.19 % to 7.44 % increase in the compressive

strength of the concrete due to the addition of 5% fly ash and 2% calcium

nitrate.

There is 6.48 % increase in the compressive strength of the

concrete prepared using potable water, 6.90 % increase in the compressive

strength of the concrete prepared using untreated textile effluent and 6.96 %

increase in the compressive strength of the concrete prepared using treated

textile effluent after 28 days of testing. The increase in the compressive


untreated and treated textile effluent after 2.5 years respectively. For the

remaining test duration of 180 days, 1 year and 2 years, the compressive

strength of the concrete is increasing gradually. It is observed that the

compressive strength of the concrete rapidly increases up to a period of 1 year

and later on the increase in the compressive strength of the concrete is

reduced. There is 6.45 % to 6.96 % increase in the compressive strength of

the concrete due to the addition of 5% fly ash and 2% calcium nitrate

admixture at the early days of testing (Krishnaswami et al 2007). The increase

in the compressive strength of the concrete due to the addition of admixture is

because of the hardening of the internal structure of the concrete and

reduction in permeability of the concrete (Ismail Yurtdas et al 2006).

122

22

24

26

28

30

0 200 400 600 800 1000


Com

pres

sive

stre

ngth

(MPa

)


Figure 3.31 Comparison of compressive strength of the concrete

prepared using potable water, untreated and treated

tannery effluents

23

24

25

26

27

28

29

30

0 200 400 600 800 1000


Com

pres

sive

stre

ngth

(MPa


Figure 3.32 Comparison of compressive strength of the concrete

prepared using potable water, untreated and treated textile

effluents

123

The Figure 3.33 shows the compressive strength test in progress.

Figure 3.33 Compressive strength test in progress

It is observed that the compressive strength of the concrete blended

with 5% fly ash and 2% calcium nitrate admixture is more than that of the

concrete blended with 5% fly ash and concare admixture (2.5% concare is


added with the concrete prepared using textile effluent). Hence it is concluded

that there is no major adverse effect on the compressive strength of the

concrete prepared using tannery and textile effluents.

3.3.10 Studies on the Tensile Strength of the Concrete

Tensile strength of the concrete is one of the basic and important

properties of the concrete. The knowledge of the tensile strength of the

concrete is required for the design of the concrete structural elements subject

to transverse shear, torsion, shrinkage and temperature. This is an indirect test

124

to determine the tensile strength of the concrete cylindrical specimens. In

reinforced concrete members, considerable importance is placed on the tensile

strength of the concrete since steel reinforcement bars embedded in the

concrete are provided to resist all the tensile forces. The tensile stresses may

develop in the concrete due to drying shrinkage, rusting of steel reinforcement

bar embedded in the concrete, temperature changes etc., and hence the

knowledge of tensile strength of the concrete is very essential to ensure the

safety of the structure.

The tensile strength of the concrete prepared using potable water is

2.23MPa after 28 days and 2.40MPa after 2.5 years, the tensile strength of the

concrete prepared using untreated tannery effluent is 2.26MPa after 28 days

and 2.45MPa after 2.5 years and the tensile strength of the concrete prepared

using treated tannery effluent is 2.23MPa after 28 days and 2.43MPa after 2.5

years. The tensile strength of the concrete prepared using untreated textile

effluent is 2.26MPa after 28 days and 2.42MPa after 2.5 years and the tensile

strength of the concrete prepared using treated textile effluent is 2.25MPa

after 28 days and 2.41MPa after 2.5 years.

From the Figures 3.34 and 3.35, the tensile strength of the concrete


textile effluents is 1.35 %, 0.45 %, 1.35 % and 0.90 % respectively higher

than that of the concrete prepared using potable water after 28 days of curing.

The tensile strength of the concrete samples prepared using untreated tannery

effluent and untreated textile effluent is 0.89 % and 0.44 % higher than that of

the concrete samples prepared using treated tannery effluent and treated

textile effluent after 28 days of testing. For the remaining test duration of 180

days, 1 year and 2 years, the tensile strength of the concrete is increasing

gradually. As like as that of the compressive strength of the concrete, the

tensile strength of the concrete prepared using untreated tannery effluent and

125

untreated textile effluent is also slightly higher than that of the concrete made

of potable water. The tensile strength of the concrete (ft) varies between

0.68√fck to 0.71√fck, where fck is the compressive strength of the concrete.

The admixtures such as concare and calcium nitrate are added with

the fly ash for enhancing the durability properties of the concrete and the

effect of these admixtures on the tensile strength of the concrete are also

studied and graphically represented in the Figures 3.34 and 3.35.




tensile strength of the concrete prepared using potable water after 28 days is

2.39MPa and 2.64MPa after 2.5 years, the tensile strength of the concrete

prepared using untreated tannery effluent after 28 days is 2.47MPa and

2.71MPa after 2.5 years and the tensile strength of the concrete prepared using

treated tannery effluent after 28 days is 2.42MPa and 2.68MPa after 2.5 years.

The tensile strength of the concrete prepared using untreated textile effluent is

2.43MPa after 28 days and 2.68MPa after 2.5 years and the tensile strength of

the concrete prepared using treated textile effluent is 2.41MPa after 28 days

and 2.66MPa after 2.5 years.

There is 7.17 % increase in the tensile strength of the concrete

specimen cast using potable water, 9.29 % increase in the tensile strength of

the concrete prepared using untreated tannery effluent and 8.04 % increase in

the tensile strength of the concrete prepared using treated tannery effluent

after 28 days of testing. The increase in the tensile strength of the concrete is

10.0 %, 10.61 % and 10.29 % for potable water, untreated tannery effluent

and treated tannery effluent after 2.5 years. For the remaining test duration of

126

180 days, 1 year and 2 years, the tensile strength of the concrete is increasing

gradually. There is 7.17 % to 10.29 % increase in the tensile strength of the

concrete due to the addition of 5% fly ash and concare admixture (2.5%

concare is added with the concrete prepared using tannery effluent and 2.0%

concare is added with the concrete prepared using textile effluent). There is

7.17 % increase in the tensile strength of the concrete prepared using potable

water, 8.0 % increase in the tensile strength of the concrete prepared using

untreated textile effluent and 7.11 % increase in the tensile strength of the

concrete prepared using treated textile effluent after 28 days of testing. The

increase in the tensile strength of the concrete is 10.00 %, 10.74 % and 10.37

% for potable water, untreated textile and treated textile effluent after 2.5

years. For the remaining test duration of 180 days, 1 year and 2 years, the

tensile strength of the concrete is increasing gradually. There is 7.11 % to

10.74 % increase in the tensile strength of the concrete due to the addition of

5% fly ash and concare admixture (2.5% concare is added with the concrete

prepared using tannery effluent and 2.0% concare is added with the concrete

prepared using textile effluent) for untreated and treated tannery effluents,

untreated and treated textile effluents.

When 5% fly ash and 2% calcium nitrate are added, the tensile

strength of the concrete prepared using potable water is 2.39MPa after 28 days

and 2.64MPa after 2.5 years, the tensile strength of the concrete prepared

using untreated tannery effluent is 2.48MPa after 28 days and 2.72MPa after

2.5 years and the tensile strength of the concrete prepared using treated

tannery effluent is 2.43MPa after 28 days and 2.69MPa after 2.5 years. The

tensile strength of the concrete prepared using untreated textile effluent is

2.44MPa after 28 days and 2.69MPa after 2.5 years and the tensile strength of

127

the concrete prepared using treated textile effluent is 2.41MPa after 28 days

and 2.67MPa after 2.5 years.

2

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3

0 200 400 600 800 1000


Tens

ile st

reng

th (M

Pa)


Figure 3.34 Comparison of tensile strength of the concrete prepared

using potable water, untreated and treated tannery effluents

2

2.2

2.4

2.6

2.8

3

0 200 400 600 800 1000


Tens

ile st

reng

th (M

Pa)


Figure 3.35 Comparison of tensile strength of the concrete prepared

using potable water, untreated and treated textile effluents

128

By the addition of 5% fly ash and 2% calcium nitrate admixture,

there is 7.17 % increase in the tensile strength of the concrete prepared using

potable water, 9.73 % increase in the tensile strength of the concrete prepared

using untreated tannery effluent and 8.48 % increase in the tensile strength of

the concrete prepared using treated tannery effluent after 28 days of testing.

The increase in the tensile strength of the concrete is 10.00 %, 11.02 % and

10.70 % for potable water, untreated tannery effluent and treated tannery

effluent after 2.5 years. For the remaining test duration of 180 days, 1 year

and 2 years, the tensile strength of the concrete is increasing gradually. There

is 7.17 % to 11.02 % increase in the tensile strength of the concrete due to

addition of 5% fly ash and 2% calcium nitrate. There is 4.48 % increase in the

tensile strength of the concrete prepared using potable water, 7.96 % increase

in the tensile strength of the concrete prepared using untreated textile effluent

and 7.11 % increase in the tensile strength of the concrete prepared using

treated textile effluent after 28 days of testing. The increase in the tensile


untreated textile effluent and treated textile effluent after 2.5 years. For the

remaining test duration of 180 days, 1 year and 2 years, the tensile strength of

the concrete is increasing gradually. There is 4.48 % to 11.16 % increase in

tensile strength of the concrete due to the addition of 5% fly ash and 2%

calcium nitrate admixture at the early days of testing.

The Figure 3.36 shows the tensile strength test in progress.

129

Figure 3.36 Tensile strength test in progress

By the addition of 5% fly ash with either concare (2.5% concare is


added with the concrete prepared using textile effluent) or 2% calcium nitrate,

there is slight increment in the tensile strength of the concrete. It is concluded

that there is no significant effect in replacing potable water with tannery and

textile effluents on the tensile strength of the concrete.

3.3.11 Studies on the Flexural Strength of the Concrete for Plain

Cement Concrete Beams

It is a well known fact that concrete is relatively strong in

compression and weak in tension.

The flexural strength of the concrete prepared using potable water

is 3.25MPa after 28 days and 3.75MPa after 2.5 years, the flexural strength of

130

the concrete prepared using untreated tannery effluent is 3.50MPa after 28

days and 3.75MPa after 2.5 years and the flexural strength of concrete

prepared using treated tannery effluent is 3.25MPa after 28 days and 3.75MPa

after 2.5 years as depicted in Figure 3.37. The flexural strength of the concrete

prepared using untreated textile effluent is 3.50MPa after 28 days and

3.75MPa after 2.5 years and the flexural strength of the concrete prepared

using treated textile effluent is 3.25MPa after 28 days and 3.75MPa after 2.5

years as shown in Figure 3.38.

It is evident from the Figures 3.37 and 3.38, the flexural strength of

the concrete beams prepared using untreated and treated tannery effluents,

untreated and treated textile effluents is 7.69 %, 0 %, 7.69 % and 0 %

respectively higher than that of the concrete prepared using potable water. At

the end of 2.5 years the flexural strength of the concrete is almost same for the

concrete made of potable water, untreated and treated tannery effluents,

untreated and treated textile effluents. For the remaining test duration of 180

days, 1 year and 2 years, the flexural strength of the concrete is increasing

gradually and almost equal for all the concrete specimens prepared using

potable water, untreated and treated tannery effluents, untreated and treated

textile effluents. As like as the compressive strength of the concrete, the

flexural strength of the concrete cast using untreated tannery effluent and

untreated textile effluent is also slightly higher than that of the concrete made

of potable water. The flexural strength of the concrete (fs) varies between

0.40√fck to 0.42√fck, where fck is the compressive strength of the concrete.

Since there is no effect and marginal increase in flexural strength of the

concrete by adding 5% fly ash with either concare (2.5% concare is added


with the concrete prepared using textile effluent) or 2% calcium nitrate, it is

not discussed in detail (Figures 3.37 and 3.38). It is concluded that the

flexural strength of the concrete is almost same for all the concrete samples

131

prepared using potable water, tannery and textile effluents with and without

the addition of the admixtures.

3

3.25

3.5

3.75

4

4.25

0 200 400 600 800 1000


Flex

ural

stre

ngth

(MPa

)


Figure 3.37 Comparison of flexural strength of plain cement concrete

beams prepared using potable water, untreated and treated

tannery effluents

3

3.25

3.5

3.75

4

0 200 400 600 800 1000


Flex

ural

stre

ngth

(MPa

)


Figure 3.38 Comparison of flexural strength of plain cement concrete

beams prepared using potable water, untreated and treated

textile effluents

132

The Figure 3.39 shows the flexural strength test in progress.

Figure 3.39 Flexural strength test in progress

3.3.12 Studies on the Failure Load of the (RCC) Beam

This is the practical and typical field condition and the knowledge

of the failure of the reinforced cement concrete (RCC) beam is essential,

while the potable water is replaced with the tannery and textile effluents.

Since there is considerable effect on reinforcement bar embedded in the

concrete due to induced corrosion, the effect on the reinforced concrete beam

has to be necessarily studied.

The failure load of the RCC beam prepared using potable water is

31.00 KN after 28 days and 33.90 KN after 2.5 years, the failure load of the

RCC beam prepared using untreated tannery effluent is 31.20 KN after 28

days and 34.00 KN after 2.5 years and the failure load of the RCC beam

133

prepared using treated tannery effluent is 31.00 KN after 28 days and 34.00

KN after 2.5 years. The failure load of the RCC beam prepared using

untreated textile effluent is 31.10 KN after 28 days and 34.10 KN after 2.5

years and the failure load of the RCC beam prepared using treated textile

effluent is 31.00 KN after 28 days and 34.00 KN after 2.5 years. The failure

load is almost same for all the RCC beam specimens prepared irrespective of

using various waters as graphically depicted in Figures 3.40 and 3.41.

The failure load of the RCC beam using untreated and treated

tannery effluents, untreated and treated textile effluents is 0.65 %, 0 %, 0.32

% and 0% respectively more than that of the concrete prepared using potable

water. After 2.5 years, the failure load of the RCC beam prepared using


is 0.29 %, 0.29 %, 0.59 % and 0.29 % respectively more than that of the

concrete prepared using potable water. Approximately there is 7.74 % to 7.05

% increase in the failure load of the RCC beam prepared using potable water

and untreated tannery and textile effluents up to one year, but there-after the

increase in failure load of the RCC beam is only 1.50 % to 1.80 % until 2.5

years.

There is no significant effect on the failure load of the RCC beam

even after adding 5% fly ash along with either concare (2.5% concare is


added with the concrete prepared using textile effluent) or 2% calcium nitrate

(Figures 3.40 and 3.41). It is concluded that there is no disastrous effect on

the failure load of the RCC beam prepared by using the tannery and textile

effluents.

134

30

31

32

33

34

35

0 200 400 600 800 1000


Load

in K

NPWUTTTTPW with CUTT with CTT with CPW with CNUTT with CNTT with CN

Figure 3.40 Comparison of failure load of reinforced cement concrete

beam prepared using potable water, untreated and treated

tannery effluents

30

31

32

33

34

35

0 200 400 600 800 1000


Load

in K

N


Figure 3.41 Comparison of failure load of reinforced cement concrete

beam prepared using potable water, untreated and treated

textile effluents

135

The Figures 3.42 and 3.43 shows the loading and testing of RCC

beams and specimens subjected to failure load test.

Figure 3.42 Loading and testing of RCC beams

Figure 3.43 Specimens subjected to failure load test of RCC beams

136

3.3.13 Studies on the Bond Strength of the Concrete

The bond strength of the concrete that exists between the cement

paste and the embedded steel reinforcement bar in the concrete is of

considerable importance. A perfect bond existing between the concrete and

the steel rebar is one of the important causes for the durability of the

reinforced concrete structures. The bond strength of the concrete depends

upon the friction and adhesion between the concrete and the embedded

reinforcement bars. The roughness of the steel surface is also one of the

important factors affecting the bond strength of the concrete. The pull out test

is carried out to determine the bond strength of the concrete developed

between the concrete and the embedded reinforcement bar. Due to the

presence of chlorides in the tannery and textile effluents, used for preparing

the concrete, the threat of corrosion of the reinforcement bar embedded in the

concrete is a major concern. Hence the studies related to corrosion of the

reinforcement bar embedded in the concrete and bond behavior of the

concrete have to be carried out (Lan Chung et al 2008).

The bond strength of the concrete prepared using potable water,

untreated and treated tannery effluents after 28 days is 1.43MPa, 1.49MPa

and 1.46MPa respectively. The bond strength of the concrete prepared using

potable water is 4% less than that of the concrete specimen cast using

untreated tannery effluent and 2.09 % less than the concrete specimen cast

using treated tannery effluent. Almost the same trend is observed for the

remaining test duration of 180 days, 1 year, 2 years and 2.5 years. When 5%

fly ash and 2.5% concare are added while preparing the concrete, the bond

strength of the concrete prepared using potable water, untreated and treated

tannery effluents after 28 days are 1.51MPa, 1.56MPa and 1.54MPa

respectively. There is an increase of 5.59%, 4.69%, and 5.48% in bond

strength of the concrete by the addition of 5% fly ash and 2.5% concare with

137


effluents respectively. The bond strength of the concrete goes on increasing in

the range of 4.40% to 5.70% for the other duration of testing. By the addition

of 5% fly ash and 2.0% calcium nitrate, there is an increase of 6.29%, 5.37%

and 6.16% of bond strength of the concrete prepared using potable water,

untreated and treated tannery effluents respectively. It is observed that there is

a considerable increase in the bond strength of the concrete with the addition

of the admixtures which are represented graphically in Figure 3.44.

When the corrosion is induced, the bond strength of the concrete

prepared using potable water, untreated and treated tannery effluents after 28

days and 2.5 years is 0.44MPa, 0.46MPa, 0.45MPa and 0.56MPa, 0.57MPa,

0.57MPa respectively. The bond strength of the concrete prepared using

potable water is 4.55% less than that of the concrete specimen cast using

untreated tannery effluent and 2.27 % less than the concrete specimen cast

using treated tannery effluent. There is 27.27%, 29.55% and 26.67% increase

in the bond strength of the concrete after 2.5 years. Due to corrosion of the

rebar, the bond strength of the concrete is largely reduced (Figure 3.44).

When 5% fly ash and 2.5% concare are added, the bond strength of


effluents after 28 days and 2.5 years is 0.91MPa, 0.93MPa, 0.91MPa and

1.01MPa, 1.04MPa, 1.02MPa respectively as shown in the figure 3.34. Due to

the addition of fly ash and concare admixture, there is 106.82%, 102.17%,

102.22% increase in bond strength of the concrete prepared using potable

water, untreated and treated tannery effluents after 28 days of testing. By the

addition of 5% fly ash and 2.0% calcium nitrate, there is 113.64%, 106.52%,

108.89% increase in the bond strength of the concrete prepared using potable

water, untreated and treated tannery effluent after 28 days of testing. There is

138

more than 102.22% increase in the bond strength due to the addition of the

admixtures. The effects are represented graphically in Figure 3.45.

1.4

1.5

1.6

1.7

1.8

0 200 400 600 800 1000


Bond

stre

ngth

(MPa

)


Figure 3.44 Comparison of bond strength of the concrete prepared using

potable water, untreated and treated tannery effluents

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 200 400 600 800 1000


Bond

stre

ngth

(MPa

)



potable water, untreated and treated tannery effluents (after

induced corrosion)

139

The bond strength of the concrete prepared using potable water,

untreated and treated textile effluents after 28 days is 1.43MPa, 1.46MPa and

1.45MPa respectively. The bond strength of the concrete prepared using

potable water is 2.09% less than that of the concrete specimen cast using

untreated textile effluent and 1.39% less than that of the concrete specimen

cast using treated textile effluent. Almost the same trend is observed for the

remaining test duration of 180 days, 1 year, 2 years and 2.5 years. When 5%

fly ash and 2.0%concare admixture are added, the bond strength of the

concrete prepared by using potable water, untreated and treated textile

effluents after 28 days are 1.51MPa, 1.54MPa and 1.52MPa respectively.

There is an increase of 5.59%, 5.47%, and 4.82% in the bond

strength of the concrete by adding 5% fly ash and 2.0% concare while

preparing the concrete prepared by using potable water, untreated and treated

textile effluents respectively. The bond strength of the concrete increases in

the range of 4.40% to 5.90% up to 2.5 years of testing. By the addition of 5%

fly ash and 2% calcium nitrate admixture, there is an increase of 6.29%,

6.84% and 6.21% of the bond strength of the concrete prepared using potable

water, untreated and treated textile effluents respectively. It is observed that

there is increase in the bond strength of the concrete by the addition of the

admixtures. The effects are shown graphically in Figure 3.46.

By induced corrosion, the bond strength of the concrete prepared

using potable water, untreated and treated textile effluents after 28 days and

2.5 years is 0.40MPa, 0.42MPa, 0.42MPa and 0.53MPa, 0.55MPa, 0.55MPa

respectively. The bond strength of the concrete prepared using potable water

is 5.00% less than that of the concrete specimen cast using untreated textile

effluent and 5.00 % less than the specimen using treated textile effluent.

There is 32.50%, 30.95% and 30.95% increase in the bond strength of the

concrete after 2.5 years prepared by using potable water, untreated and treated

140

textile effluents. Due to corrosion of the rebar embedded in the concrete, the

bond strength of the concrete is largely reduced.

The bond strength of the blended concrete (5% fly ash and 2.0%

concare) prepared using potable water, untreated and treated textile effluents

after 28 days and 2.5 years is 0.87MPa, 0.89MPa, 0.88MPa and 0.98MPa,

1.00MPa, 0.99MPa respectively. Due to the addition of 5% fly ash and 2.0%

concare, there is 117.50%, 111.90%, 109.52% increase in the bond strength of

the concrete prepared by using potable water, untreated and treated textile

effluents after 28 days of testing. By the addition of 5% fly ash and 2%

calcium nitrate, there is 125.00%, 121.43%, 119.05% increase in the bond

strength of the concrete prepared by using potable water, untreated and treated

textile effluents after 28 days of testing. There is more than 109.52% increase

in the bond strength of the concrete due to the addition of the admixtures as

graphically illustrated in the Figure 3.47.

1.4

1.5

1.6

1.7

1.8

0 200 400 600 800 1000


Bond

stre

ngth

(MPa

)



potable water, untreated and treated textile effluents

141

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 200 400 600 800 1000


Bond

stre

ngth

(MPa

)



potable water, untreated and treated textile effluents (after

induced corrosion)

It is observed from the experimental results that there is good

improvement in the bond strength of the concrete by the addition of 5% fly

ash and concare (2.5% concare is added with the concrete prepared using

tannery effluent and 2.0% concare is added with the concrete prepared using

textile effluent) with the concrete or 5% fly ash and 2% calcium nitrate with

the concrete.

3.4 COST BENEFIT ANALYSIS

The treatment of effluents (processed water/waste water) in the

tanneries and textile processing units incur approximately about 45 to 80

paise per litre of processed water. The transport cost from the tanneries and

the textile processing units to the site (where the construction activity takes

place) is approximately around 35 to 45 paise per litre of water, if the

construction site is within 30-40 kilometres from the tanneries and the textile

142

processing units, which accounts 2.0% of the total cost of the building. The

admixtures to be added with the concrete costs approximately about 3% of the

total cost of the building. The coating of the reinforcement bar to be

embedded in the concrete costs approximately 1% of the total cost of the

building. Altogether approximately 6.0% cost of the building is increased.

The cost of buying potable water in scarcity season costs approximately 1%

of the total cost of the building. So there is 5.0% increase in the total cost of

the building. Even though there is an increase in the cost (5.0%) of the

building constructed using tannery and textile effluents, it reduces the water

demand considerably during the water scarcity period and also the tannery

and textile effluents are safely disposed. It also reduces the pollution, protects

the environment and conserves the non renewable resources (water).

Documents

CHAPTER 3 RESULTS AND DISCUSSIONshodhganga.inflibnet.ac.in/bitstream/10603/33583/8/08_chapter 3.pdf · sulphate attack, chloride attack and corrosion, respective tests were carried