Effect of Rha

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Technology and Innovation for Sustainable Development Conference (TISD2008)Faculty of Engineering, Khon Kaen University, Thailand

28-29 January 2008

Effects of Rice Husk Ash on Characteristics of Lightweight Clay Brick

Danupon Tonnayopas1*, Perapong Tekasakul2 and Sarawut Jaritgnam31Department of Mining and Materials Engineering, Faculty of Engineering, Prince of Songkla University,

Hat-Yai 901122Department of Mechanical Engineering, Faculty of Engineering, Prince of Songkla University,

Hat-Yai 901123Department of Civil Engineering, Faculty of Engineering, Prince of Songkla University, Hat-Yai 90112

E-mail: [email protected]*

AbstractThe effects of rice husk ash (RHA) addition on the

physical and mechanical properties of the lightweight

building fired clay bricks were investigated. Different

proportions of RHA from 10-50% by mass were

mixed to the raw brick-clay. Higher RHA addition

required a higher water content to ensure the right drydensity. All test specimens were produced by uniaxial

hydraulic press method and fired at 1050C. Thesamples were tested by according to Thai Industrial

Standard (TIS) methods and compared with its

specifications. Up to 30% RHA addition was found to

meet TIS. It can be utilized in fired building bricks by

taking advantage of low cost and environmental

protection.

Keywords:Rice husk ash, Lightweight clay brick,Physical and mechanical properties, Electrical

resistance

1. IntroductionLarge amount of paddy production and the

development of agro-based industries in many

countries of the world have brought about the

production of large quantities of rice wastes, most of

which are not adequately managed and utilized. Rice

husk wastes were used for animal feed, fertilizer and

fuel for energy production, but little work has been

carried out to develop utilization of rice husk ash

(RHA) in the production of fired clay brick. Theneeds to conserve traditional clay bricks that are

facing depletion have obliged engineers to look for

alternative materials [1, 2].Environmentally friendly, energy saving recycle

property of material production has been one of the

very important research purposes for decades [3, 4, 5].

Owing to environmental regulations, the demand forhigh insulation ability bricks is increasing [6].

Thermal conductivity is a decisive factor for the heat-

engineering concept of thermal insulating material

[7]. One method of increasing the insulation ability of

brick is generating porosity in clay body. However,

combustible, organic residues of pore-formingadditives are most frequently used for this purpose [8,

9]. Furthermore, several types of ash are also utilized

for clay bricks [10, 11]. Rahman [12] investigated

properties of clay-sand-mixes different percentages of

RHA and burnt at 1000C for 2, 4 and 6 hours. He

obtained lightweight brick with optimum firing

duration of 4 h and used in load bearing walls.The main objective of this study is to investigate

the effects of RHA addition on the properties of fired

building bricks, without degrading their properties

based upon the Thai Industrial Standard (TIS) [13]. ,

was accumulated during rice processing on the plants,

2. Materials and MethodsRHA collected from a local rice mill, Na Mom

district, Songkhla, Thailand. It was burnt in open air

ambient. Upon collection, the RHA sample was dried

in an oven at 100C for one day. A clayey soil (CS)

sample was contributed from a local conventional

brick manufacturing plant, Ban Pru, Hat-Yai. The

basic physicochemical characteristics, including

particle size distribution was measured by

sedimentation technique with a laser scattering

particle size analyzer model LS 230, Small Volume

Module Plus of Beckman Coulter, pH, basic chemical

elements based on X-ray fluorescence (XRF). The

differential thermal analysis (DTA) of the RHA

sample was simultaneously conducted in a DTA

model PerkinElmer, DTA7 instrument operating

under a flow of nitrogen (20 ml/min) and heating rate

of 10C/min until the maximum temperature of1300C, and particle true density were determined by

using a Multipycnometer model MUP-2 Quata

chrome apparatus. A CS sample derived from crushed

normal brick clay was obtained from a local brick

manufacturing plant. Upon collection, it was ground

with a crushing machine. Particle size of rice husk ash

and brick clay were determined with laser scattering

particle size analyzer (LS 230, Small Volume Module

Plus of Beckman Coulter). The pH values of brick CS

and RHA were determined by mixing of 20 g in

distilled water 30mL for a beaker 50mL then settled

for 20 h before mixture solution was measured in

potential and ion pH Redox.The RHA and brick CS powder were prepared

by cone crusher and then ball milling for 6 h, sieving

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at 200 mesh. Atterberg limits was conducted to obtain

the plastic nature of the brick CS according to ASTM

D 4318 [14] and compacted various proportions of

RHA and brick clay mixture to establish the optimum

moisture content (OMC) in humidifying the brickmaking process (Table 1) [15]. The RHA-brick clay

powder mixtures were composed for 1 h in a jar millthen prepared in batches and used axially hydraulic

press 1.00 MPa (10 bars) into a series of Thai

standard brick molds (140 mm 65 mm 60 mm). A

brick clay (CS) only mixture was prepared as a

reference specimen. The molded specimens were air-

dried at room temperature for 24 h, and then oven

dried at 1005C for another 24 h to remove the water

content, all of the mold green specimens were fired at

optimized 1050C [11] in a electrical furnace under

heating rate of 2C/min from room temperature to

500C soaking 30 minutes and adjusted rate of

5C/min until the maximum temperature, followed by

1 h soaking. The specimens were cooled to roomtemperature in the furnace.

As required by the TIS-77 procedure for

building bricks, the produced solid bricks then

subjected to a series of test, including firing

shrinkage, weight load on ignition (ASTM C62),

water absorption, bulk density, and cold crushing

strength [13]. The experimental results obtained on at

least ten fired specimens for all categories. The water

absorption capacity was determinedaccording to TIS

procedure.

Table 1. Elaborated RHA bricks mixtures and

humidity.

Raw materials (wt%)Mixture

Items CS RHA

OMC

%

CS or RHA0 100 0 21.80

RHA10 90 10 22.80

RHA20 80 20 24.20

RHA30 70 30 25.60

RHA40 60 40 26.21

RHA50 50 50 26.98

The bulk density was measured dividing the dry

mass by the average external volume. Linear

shrinkage was determined by the brick length afterdrying at 110C and the brick length after firing at a

temperature stages using a Vernier caliper OKURA

(precision 0.05 mm). The crushing strength using a

ELE International test machine of 272 t capacity at

85.5-208.2 kg/cm2/s loading rate.

3. Result and DiscussionThe RHA has major oxide compositions such as

SiO2, K2O and CaO and minor contents of Fe, Ca, and

Na oxides Al2O3 of (Table 2), were in range of

refractory materials (ASTM C 618). RHA and brick

clay had been a pH of 9.97 and 3.40, respectively. It is

indicated that mixture materials can be treated asneural materials. Upon that, it can be reduced

harmfully and prolong the useful life of electric coil in

furnace.The particle size distribution of RHA and CS

are relatively same significant and poor grading

(Figure 1). The uniform distributions are rather

similar and the main feature significance is the

generally larger particle sizes in the RHA (between 1

and 31 m, with average particle size of 21 m,whereas in the CS of 1-31 m with average is 20 m).

0

10

20

30

40

50

60

70

80

90

100

1 10

Diameter (Micron)

CumulativePassing(%)

100

Clayey Soil

Rice Husk Ash

Figure 1. Particle size distribution of raw materials.

Table 2. Major chemical composition of raw

materials, as determined by XRF (wt.%).

Physicochemical properties (%) RHA CS

Silicon dioxide, SiO2 48.16 58.11

Aluminium oxide, Al2O3 0.18 17.88

Iron oxide, Fe2O3 0.29 8.58

Potassium oxide, K2O 28.55 5.98

Phosphate pentoxide, P2O5 3.85 -

Calcium oxide, CaO 2.36 0.13

Magnesium oxide, MgO 3.96 1.22Titanium dioxide, TiO2 - 1.86

Manganese dioxide, MnO2 1.39 0.30

Sulfur trioxide, SO3 1.73 -

Loss on ignition 0.14 0.28

pH 9.97 3.40

True density, g/cm3 2.98 2.62

However, in the DTA result of RHA displayed

endotherm at 336.82 C and phase later of exotherm

at 872.73 C (Figure 2). It can be noted that the two

phases of RHA was might be constituted of almostsingle composition or occurred non-recrystallization.

Temperature (C)

Figure 2. DTA pattern of RHA.

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The water absorption of RHA brick has ranged

from 9.63% of normal brick (CS) to 41.22% of

RHA50 brick. It can be observed that the increase in

the RHA replacement give rise to an increase in the

water absorption (Figure 3). According to TIS-37 themaximum allowed value of water absorption is 25%

for the first-class building brick and below 15% forsecond-class category use of the brick. The RHA

proportion effect on the linear shrinkage (Figure 4) is

completely different to that observed for the weigh

loss (Figure 5). Less linear shrinkage is a factor that

may contribute to reduce the risk of appearance of

cracks and dimensional defects in bricks. On the other

hand, an excessive amount of RHA can promote

cracks due to low particle bonding and, consequently,

reduce the mechanical strength.

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50

Rice Husk Ash Content (%)

Water

Absorp

tion(%

)

Figure 3.Water absorption of RHA bricks.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 10 20 30 40 5


LinearShrinkage(%)

0

Figure 4. Linear shrinkage of RHA bricks.

0

5

10

15

20

25

30

35

0 10 20 30 40 5


Weig

htLoss

(%)

0

Figure 5. Weight loss of RHA bricks

On the contrary, bulk density ranged from 1.13

g/cm3 (RHA50) up to a maximum of 1.88 g/cm3 (CS).

The increase in the amount of RHA addition causes a

reduction in the brick density (Figure 6). The main

reason for such a result is the burning of RHA

addition as an organic material which can easily burn

out during the sintering period. In the viewpoint,electrical resistance confirmed the behavior of

thermal insulation brick (Figure 7). Cold crushing

strength (CCS) values vary from 3.76 to 37.09 MPa,

where the highest values are displayed for the

specimens with RHA0 brick. All values show

dramatically decrease in CCS with an increase in the

replacement of CS content (Figure 8).

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

0 10 20 30 40 50


BulkDen

sity(%)

Figure 6. Bulk density of RHA bricks.

0

10

20

30

40

50

60

70

0 10 20 30 40 50


ElectricalResistance

)

aOhm/cm

M

eg

(

Figure 7. Electrical resistance of RHA bricks.

0

5

10

15

20

25

30

35

40

0 10 20 30 40


Compress

ive

Strength

(MPa)

50

Figure 8. Cold crushing strength of RHA bricks.

RHA addition increases the required water

content for plasticity (Table 1). Particle size

characteristics of the RHA do not create any problemduring shaping at used addition levels.

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Moreover, RHA is easily burnt out and it has

wide range burning from the clay body during firing.

No black coring and bloating were observed in texture

after firing. Based on the results in Figure 3 the water

absorption for only bricks mixed 30-50% RHA ishigher than 25%, and thus they are not met TIS-77.

An increase in the content of the RHA additionleads to an decrease in the firing linear shrinkage

(Figure 4). Firing weight loss increased as the amount

of RHA additive increased (Figure 5). Also an

increase of RHA leads to an increase in the open

porosity and this effect decreased the bulk density

(Figure 6) and improved the thermal insulating

properties with confirm of measuring electrical

resistance behavior (Figure 7), particularly at 40-50%

RHA.In addition to CCS values decrease with

increasing the amount of RHA additive (Figure 8). A

90% reduction in the CCS of control brick is obtained

from the 50%RHA replacement (RHA50). Therefore,these values meet the TIS-77 required specification on

fired bricks (>3.5 MPa).

4. ConclusionsThis investigation had demonstrated a feasible

way of using incinerated RHA as brick clay toproduce a high quality brick. Organic characteristics

of RHA give extra contribution to the heat input of

the furnace. According to test results, a mixture of up

to 50% RHA additives by weight can be used in

building fired brick production, particularly for

lightweight brick. The most economical firing

temperature was determined as 1050C. RHA can beused as an organic kind of pore-forming additive in

the clay body without any harmful effect on the other

brick manufacturing parameters.

Usage of RHA material in the clay mixture

improved the physical and mechanical properties. The

use of RHA waste in brick production provides an

economical contribution and also serves as the energy

efficiency materials for building. It is indicated that

RHA could be an alternative raw material toproduction of clay bricks and friendly environments.

Acknowledgments

This research has been supported by a grantPromotion of Energy Conservation Fund at 95/2547

under contract number Project 03-178-47-71 of theEnergy Policy and Planning Office (EPPO), Ministry

of Energy, Thailand.

References[1] Dondi, M., Marsigli, M. and Fabbri, B. 1997.

Recycling of Industrial and Urban Waste in Brick

Production-A Review, Tile Brick International,

13: 218-225.

[2] Tonnayopas, D. and Na-Phattalung, P., 1997.

Marble powder and rubber sawdust bricks, Proc.

of the 1997 Annual Conf. of the Engineering

Institute of Thailand, Bangkok, Thailand, Nov. 20-

23, 1997: 322-328. (in Thai)

[3] Malhotra, S.K. and Tehri, S.P. 1996. Development

of Bricks from Granulated Blast Furnace Slag,

Construction and Building Materials, 10(3): 191-

193.

[4] Weng, C-H., Lin, D-F. and Chiang, P.C. 2003.Utilization of Sludge as Brick Materials,

Advanced Environment Research, 7(3): 679-685.[5] Acosta, A., Iglesias, I., Aineto, M., Romero, M.

and Rincon, J. Ma.2002. Utilisation of IGCG Slag

and Clay Steriles in Soft Mud Bricks (by Pressing)

for use in Building Bricks Manufacturing, Waste

Management, 22(8): 887-891.

[6] Sabrah, B.A. and Burham, N. 1981. Thermal

Studies of Basalt and Clay for the Manufacture of

Building Bricks, Thermochimica Acta, 51(2-3):

315-323.

[7] Dondi, M., Mazzanti, F., Principi, P., Raimondo,

M. and Zanarini, G. 2004. Thermal Conductivityof Clay Bricks, Journal Material of Civil

Engineering, 16(1): 8-14.

[8] Demira, I., Baspnara, M.S. and Orhan, M. 2005.Utilization of Kraft Pulp Production Residues in

Clay Brick Production, Building and

Environment, 40: 15331537.

[9] Kaoien, P., Tonnayopas, D., Jaritgnam, S. and

Masae, M. 2005. Characteristic of Lightweight

Clay Brick with Fresh Rice Husk, Proceedings 4th

PSU Engineering Conf., Songkhla, Dec. 8-9,

2005: MnE-31-MnE-35. (in Thai)

[10] Dondi, M., Ercolani, G., Guarini, G. and

Raimondo, M. 2002. Orimulsion Fly Ash in ClayBricks-Part 1 Composition and Thermal Behavior

of Ash, Journal European Ceramic Society,

22(11): 1729-1735.

[11] Tonnayopas, D. and Ponsa, A. 2005.

Benefication of oil palm fibre fuel ash in making

construction clay brick, Proceedings of 4th PSU

Engineering Conf., Songkhla, Dec. 8-9, 2005: CE-

7-CE-12. (CD-ROM) (in Thai)[12] Rahman, M.A. 1987. Properties of Clay Sand-

Rice Husk Ash Mixed Bricks, Int. Journal Cement

Composites and Lightweight Concrete, 9(2): 105-

108.

[13] TIS 77, 1974. Standards Specification forBuilding Brick (Solid Masonry Units Made from

Clay or Shale), Thai Industrial Standard Institute,

p. 4. (in Thai)

[14] ASTM D4318-00 Standard Test Methods for

Liquid Limit, Plastic Limit, and Plasticity Index

Of Soils.

[15] ASTM D698-00A Standard Test Methods for

Laboratory Compaction Characteristics of Soil

Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-

m/m3).

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Effect of Rha