Studies on the effect of seawater & Normal water intrusion in ......1 Studies on the effect of seawater & Normal water intrusion in Sea sand on Concrete Cubes Mr.Sakthivel.R1, Dr.V

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Studies on the effect of seawater &Normal water intrusion in Sea sand on

Concrete CubesMr.Sakthivel.R1, Dr.V. Murugaiyan2

1 Research Scholar, 2 Professor, Department of Civil Engineering, Pondicherry Engineering College,Puducherry, India

E-mail: [email protected]

Abstract– The aim of this work is to study the Effects of Sea water encroachment in concrete cubes placed in Sea sand nearcostal zones. Paper inspects the influence of Normal water & Seawater curing in concrete cubes which is concealed on Seasand. Cement concrete cubes of 150x150x150mm were cast using normal water and cured with seawater & normal water withtwo different mix proportions of M-20 & M-30 with 0.45 water cement ratio and compressive strength & NDT test wereperformed during 28th day and 84th day. Totally 72 specimen were cast with normal water. Cement in addition with fly ash class-C of 20% and 30% was also used for this investigation.

Key words: Compressive Strength, fly ash, Sea Sand, Seawater, NDT.

INTRODUCTIONDurability of Concrete structures in CostalEnvironment has been an issue for many years,due to the perception of sea water to concrete. InIndia, marine environment of soils are Subjectedto major change in their index and EngineeringProperties of soil. The strength of concretemainly depends on the concrete mix, types ofcuring, water cement ratio, aggregates andcement types. Water is an important constituentof concrete as it participates in the chemicalreaction with cement. The addition of fly ashclass –C with cement in concrete mix is used inthis investigation in Sea sand.

Md. Moinul Islam, Md. Saiful Islam, Md. Al-Amin and Md. Mydul Islam in 2012 examinedthat Suitability of sea water on curing andcompressive strength of structural concrete as apart of durability study, this paper describes theeffect of sea water on compressive strength ofconcrete when used as mixing and curing water.Concrete specimens were cast from four differentgrades and plain water as well as sea water wasused as mixing water in making the testspecimens. Test specimens were cured under seawater as well as plain water upto 180 days. Testresults indicate that sea water is not suitable formixing as well as curing of concrete. Concretespecimen made and cured with sea water

exhibits compressive strength loss of about 10%compared to plain water mixed and curedconcrete.

C.Marthong, T.P.Agrawal in 2012 examined theEffect of Fly Ash Additive on ConcreteProperties. This paper reports a comparativestudy on effects of concrete properties whenOPC of varying grades 33, 43, 53 were partiallyreplaced by fly ash. The main variableinvestigated in this study is variation of fly ashdosage of 10%, 20%, 30% and 40%. Thecompressive strength, durability and shrinkageof concrete were mainly studied. Test resultsshows that, inclusion of fly ash generallyimproves the concrete properties upto certainpercent or replacement in all grades of OPC.

Falah M. Wegian (2010) investigated the effectsof mixing and curing concrete with sea water onthe compressive strengths and reported thatthere are increases of strengths of concrete mixedand cured in sea water at early ages and adefinite decrease for ages more than 28 days andup to 90 days.

Shetty, M. S. (3) in 2002 determined successfulperformance of a marine structure depends to agreat extent on its durability against theaggressive marine environment. Disintegrationof concretes in marine environments is mostly

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caused by chemical deterioration such assulphate attack, chloride attack and leaching.Physical deterioration from crystallization ofsoluble hydrated salts in pores of the concrete,erosion and abrasion promotes furtherdisintegration. The overall results of theseattacks on concrete are softening, cracking andpartial removal of cover concrete. This in turnexposes a fresh surface for further attack.

Dhuraria has recorded that earlier strengthscould be achieved in fly ash concrete byadjusting the various ingredients in such a waythat the quantity of cement and fly ash in thefinal mix is more than the quantity of cementreplaced. Fly ash concrete mix appeared drierthan normal concrete mix but gets satisfactorilycompacted with adequate vibrations.

Preeti Tiwari et.al (2014) performed series ofexperiments on M-30 grade and said that there ismarginal increase in the strength of cubes castand cured in salt water as compared to those ofcast and cured in fresh water at all ages of curingand concluded that there is no reduction in thestrength if we use salt water casting and Curingthe concrete.

1 MATERIALS USED1.1 SEA SAND

Sea sand is obtained from locally available placePondicherry was used for this study. The Specificgravity for sea sand is 2.51.

1.2 CEMENT

OPC- 43 confirming to IS 8112-1989 used in thisproject work. The specific gravity of cement is3.15.

1.3 COARSE AGGREGATE

Coarse aggregate of size 20mm at 60% and 12mmat 40% is used in this work. The properties ofcoarse aggregate are determined as per IS 2386-1963 to have a specific gravity of coarseaggregate is 2.60

1.4 SEA WATER

To study the effect of seawater on geotechnicalproperties of Red soil in concrete cubes.

1.5 FLY ASH

Fly ash class – C was obtained from an industrialwaste from thermal power stations. Fly ash is a

by-product of burning pulverized coal in electricpower plant.

2 METHODOLOGYThe general mix proportions are provided in IS:10262-2009, for M20 and M30 grade of concretewas arrived as 1: 1.5: 3 and 1: 0.75: 1.5 withwater-cement ratio of 0.45.

A total sample of 72 cube specimen of size150mm x 150mm x 150mm were cast and testedthe compressive strength at 28 & 84 days, Waterabsorption and Young’s modulus were noted at28 days. The various physical properties andchemical properties of Sea sand due to effects ofsea water were investigated.

3 RESULTS AND DISCUSSIONS3.1 SIEVE ANALYSIS

In order to obtain the gradation of sea sand sieveanalysis test was performed.

3.2 Specific GravitySpecific gravity of fine-grained soil wasdetermined by density bottle method as per IS:2720 (Part III/Sec 1).

3.3 Free Swell IndexAs per IS 2720, the free swell index is an changein the volume of a soil without any externalrestriction, on submergence in ordinary water.

TABLE 1

Geotechnical properties in Sea sand for 28th dayand 84th day

Description

Beforeplacingconcrete

cubes

After placingconcrete cubes

28th day 84th day

Specificgravity

2.65 2.61 2.60

Liquid limit - - -

Plastic limit - - -

Shrinkagelimit

- - -


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Plasticityindex

- - -

Free Swellindex

- - -

OMC - - -

UCC - - -

DirectShear test

300

6’49.4”250

18’32”230

46’53”

The above table shows that the Specific gravity isdecreased and direct shear value decreased afterthe effects of seawater intrusion in sea sandduring 28th day & 84th day.

3.4 Compressive Strength

The standard mould of size 150mm × 150mm ×150mm is used for testing compressive strengthduring 28th day & 84th as per IS 516:1959 forordinary mix and for the partial replacement ofFly ash class-C samples.

TABLE 4

Compressive strength of concrete with normalwater and sea water curing in Sea.

Description

M-20 M-30

28th

day84th

day28th

day84th

day

Normal watercuringwithout flyash

24.13 29.91 25.48 34.60

Normal watercuringWith fly ash20%

25.94 20.60 39.61 31.85


22.50 28.14 26.31 29.36

Sea watercuring buriedin sea sandwithout flyash

35.46 19.65 27.82 31.65

Sea watercuring buriedin sea sandwith fly ash20%

20.38 17.77 21.64 33.76

Sea watercuring buriedin Sea sand(30%)

15.85 19.40 12.05 27.62

The above table values are calculated from(CTM) test of three samples from eachdescription and average values is listed out inthe table

Fig 1: compressive strength of concrete withnormal water and sea water

The above graph shows that M-30 with normalwater curing has more strength compared withseawater during 84th day

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5

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15

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25

30

35

40

45

28thday

84thday

28thday

84thday

M-20 M-30

Normal watercuring withoutfly ash

Normal watercuringWith flyash 20%


Sea water curingburied in seasand without flyash

Compressive Strength


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3.5 Ultra-sonic pulse velocity.

An ultrasonic pulse velocity is an in-situ, non-destructive test to check the quality of concreteand its natural behaviour. Ultrasonic pulsevelocity method, involves the measurement ofthe time travel of electrically generated pulsesthrough the concrete. The pulses are applied tothe concrete; three different waves are generatedcalled longitudinal waves. Three different kindsof wave are generated. One is longitudinal orcompression waves which travel twice as fast onother two types. Second one is shear ortransverse waves are not so fast. Finally thesurface waves are the slowest one.

if the pulsed velocity is greater than 4.5 itsexcellent, if its 3.5 to 4.5 are good in condition, if3.0 to 3.5 it’s a medium ,finally below 3.0 it’sdoubtful concrete to used.

Table 4

UPV of concrete with normal water curing andsea water curing in Sea sand with & without flyash

DescriptionM-20 M-30

28th

day84th

day28th

day84th

day


4637 4657 4533 4860


4747 4357 4734 4460


4564 4364 4684 4584


4687 4704 4617 4647


4224 4344 4323 4337


4324 4664 4114 4714

The above table values are calculated from UPV testof three samples from each description and averagevalues is listed out in the table

Fig 2: UPV of concrete with normal water andsea water

The above graph shows that M-30 with normalwater curing without fly ash has more strengthcompared with seawater during 84th day.

3.6 Rebound hammer test

Schmidt’s rebound hammer is one of the non-destructive testing methods for concrete tomeasure the surface hardness. It consists of aspring hammer that side on a plunger within thetubular. When the plunger is pressed against thesurface of concrete the mass hit from the plungerit reacts to the force against the spring, thatimpact against the concrete and spring controlledthe action of mass, taking the rider with it guidescale. The rider on top of the tubular just abovemass rebound to allow the reading to be taken.The distance travelled along the concrete iscalled rebound number. This test can be doneboth horizontally and vertically manner.

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15

20

25

30

35

40

45

28thday

84thday

28thday

84thday

M-20 M-30




Sea watercuring buried insea sandwithout fly ash

UPV


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TABLE 4

Rebound hammer test of concrete with normalwater curing and sea water curing in Sea sandwith & without fly ash.

DescriptionM-20 M-30

28th

day84th

day28th

day84th

day


23 28 28 32


24 28 31 32


24 26 31 36


33 38 35 35


34 30 3335


26 34 27 37

The above table values are calculated fromRebound hammer test of three samples fromeach description and average values is listed outin the table.

Fig 3: R value of concrete with normal waterand sea water

The above graph shows that M-30 with normalwater curing without fly ash has more strengthcompared with seawater during 84th day.

ACKNOWLEDGMENTI wish my heartfull thanks to my guide Dr.V.Murugaiyan who has helped me with hisguidelines for completing this projectsuccessfully.

4 CONCLUSIONSBased on the test results, it is concluded that:

1. When compared with normal water curingand sea water curing without fly ash thecompressive strength for sea water curing isdecreased by 11.33 N/Sq.mm and 10.26N/Sq.mm for M-20 during 28Th day and 84th

day respectively.

2. When compared with normal water curingand sea water curing with fly ash class–C for20% and 30%. The compressive strength for30% fly ash is decreased with seawatercuring.

3. The ultra-sonic pulse velocity results showthat normal water curing of concrete have

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28thday

84thday

28thday

84thday

M-20 M-30




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R value


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better quality when compared to sea watercuring.

4. The Rebound hammer test value of concreteis increased during normal water curingwithout fly ash when compared with seawater without fly ash.

REFERENCE

[1] Falah M. Wegianoct 10(2010) effects of seawaterFor Mixing and curing on structuralconcrete

[2] P. Krishna raj, v. Lakshmi, s.bhanupravallika(April2014) Concrete using sea WaterInternational journal of Advanced scientific andtechnical Research

[3] Akinsolaolufemi Emmanuel, (2012)investigation of salinity Effect on compressivestrength of reinforced concrete, journal inSustainable development, Canadian centre ofscience and education

[4] S.K. kaushik, S. islam (1995) suitability of seawater for mixing structural concrete exposed toa marine environment. International journalengg research.

[5] Sagargawande, yogeshdeshmukh, (2017)comparative study of effect of salt water andfresh water on concrete. International researchjournal of engineering and technology.

[6] Preeti Tiwari, rajivchandak, R.K. yadeav .(2014)effects of salt water On compressive strength ofconcrete, international journal of Engineeringresearch& applications

[7] E,M. Mbadujea, A.U. ellinwa, effect of salt waterin the producton of concrete. June-2011 journalof Nigerian technology

[8] Concrete for marine works using opc&seawater, feb-2014 International journal of civilengineering

[9] MandarM.joshi study of different parameters ofsaline water from budana district for its use inconcrete.

[10] P. Kumar Mehta & Paulo J.M. Monteiro.“Concrete in Sea Water”, ConcreteMicrostructure, Properties and Materials.

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Studies on the effect of seawater & Normal water intrusion in ......1 Studies on the effect of seawater & Normal water intrusion in Sea sand on Concrete Cubes Mr.Sakthivel.R1, Dr.V