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ScienceDirect IERI Procedia 5 (2013) 298 – 303

2013 Interrnational Coonference on Agricultuural and Nattural Resourrces Engineeering

Use of Unnprocesssed Rice Husk Ash A and Pulverize P ed Fuel A Ash in t Prodduction of the o Self-C Compactting Conncrete Gritsada Sua-iam,, Natt Mak kul* Deepartment of Buillding Technologyy, Faculty of Induustrial Technologyy, Phranakhon Ra ajabhat University, Bangkok 102220, Thailand

Absttract We investigated i thee properties of self-compactinng concrete (SC CC) mixtures comprising ternary combinatioons of Type 1 Portlland cement (O OPC), untreated rice husk ash (RHA), ( and puulverized fuel assh (FA). The SCC mixtures w were produced with a controlled sluump flow in thee range betweenn 67.5 to 72.5 cm c diameter witth a constant tootal powder matterials content of 5550 kg/m3. RHA A and/or FA were w used to repplace in powdeer materials with 20 or 40 wtt%. The fresh and hardened propeerties includingg water requirement, workabbility, density, compressive strength development and ultrrasonic pulse veloccity were deteermined. Self-ccompacting conncrete mixturess formulated using u ternary blends b exhibiteed significant imprrovements in phhysical propertiees compared to SCC mixtures containing only y RHA or FA.

Published

by Elsevier B B.V. Open access under CC BY-NC-ND license.

B.V. © 20013The © 2013 Authors.dPublished

by Elsevier Selection andand peerpee review under responsibility of Information Research Institute Sele ection r review undeer responsibilit ty of Engineering Informattion Engineer ing Research Institute Keyw words: Self-compaacting concrete; Rice R husk ash; Puulverized fuel ashh; Workability, Mechanical M propertties

1. In ntroduction S Self-compactin ng concrete (S SCC) is a typee of high fluidiity and strength concrete deeveloped in Jaapan in 1988 to inncrease produuctivity and durability in concrete construction. SCC mixtures contain superplasticizer adm mixtures, limiteed amounts of o aggregate, and a low water-powder ratio os [1]. The chharacteristics in the fresh statee of SCC include high pennetrating ability filling abiility, and resiistance to seggregation. Higgher cement conttent and loweer coarse agggregate contennt are requireed to avoid segregation. s M Mixtures conttaining only * Corresponding author. a Tel., Fax.: +662-522-6637 E E-mail address: shhinomomo7@hottmail.com

2212-6678 © 2013 The Authors. Published by Elsevier B.V. Open access under CC BY-NC-ND license.

Selection and peer review under responsibility of Information Engineering Research Institute doi:10.1016/j.ieri.2013.11.107

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Gritsada Sua-iam and Natt Makul / IERI Procedia 5 (2013) 298 – 303

Portland cement are costly and are susceptible to aggressive substances (ions and molecules), thermal cracking, and high autogenous shrinkage [2]. The cost of SCC may be reduced by replacing a portion of the cement with pozzolanic materials derived from industrial by-products. Previous research has also demonstrated that mineral admixtures such as pulverized fuel ash (FA) or rice husk ash (RHA) improve the workability and mechanical properties of SCC mixtures [3-5]. Nearly 32 million tons of RHA were produced in Thailand in 2011 [6]. The pozzolanic activity of RHA is dependent on the particle size and surface area.

These properties may be tailored using grinding processes, although at considerable cost. Unground RHA may also be used as a cement replacement material by improving the grinding process to increase the ash particle size [7] or mixing with a filler material [8]. For instance, blends of RHA and FA exhibit improved strength and corrosion resistance [9]. Both of these by-product materials are locally available in Thailand, and their use can decrease the cost of SCC and assist in reducing secondary environmental problems related to waste disposal.

2. Experimental details 2.1. Materials A Type 1 Portland cement (OPC) complying with ASTM standards [10] was used in all of the mixtures.

The pulverized fuel ash and rice husk ash were obtained from a thermal power plant. The physical properties and chemical composition of powder materials are showed in Table 1. A polycarboxylic ether (PCE)-based superplasticizer in accordance with ASTM standard type F [11] was used as a lubricant component in the SCC mixtures. Silica sand with a nominal maximum size of 4.75 mm and crushed calcium-based limestone rock with a nominal maximum size of 16.0 mm were also used as aggregates.

Table 1. Chemical composition and physical properties of powder materials.

Type 1 Portland Cement

Pulverized fuel ash

Rice husk ash

Chemical composition (% by mass) Silicon dioxide (SiO2)

17.21

40.51

93.44

Aluminum oxide (Al2O3)

3.81

21.52

0.21

Iron (III) oxide (Fe2O3)

3.60

13.41

0.18

Magnesium oxide (MgO)

1.17

2.10

0.43

Calcium oxide (CaO)

67.55

13.99

0.76

Sodium oxide (Na2O)

0.20

1.44

0.05

Potassium oxide (K2O)

0.29

2.20

1.98

Sodium oxide (SO3)

3.25

4.00

0.16

2.44

0.49

1.27

Loss on Ignition (% by mass)

Physical properties Mean particle size (Îźm)

24.28

43.86

39.34

Specific gravity

3.15

2.58

2.24

632

1487

370

2

Specific surface area (cm /g)

2.2. Mix proportions

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The SCC proportions were designed to produce a controlled slump flow in the range between 67.5 to 72.5 cm diameter. The OPC in the mixtures was replaced with 0, 20, or 40 wt% of RHA and/or FA according to the composition chart in Table 2. The mixtures were identified using the notation RHAyFAz, in which y and z are the replacement percentage of RHA and FA %wt of total powder materials. The polycarboxylate-based superplasticizer (HRWR) dosage was fixed at a 2.0 wt% of total powder materials.

Table 2. Mix proportion of SCC mixes.

Materials (kg/m3) Mix

Cementitious Total powder

Cement

Control

550

RHA20

550

Aggregate

HRWR (%)

Rice husk ash

Pulverized fuel ash

Fine

Coarse

550

0

0

813

708

2.0

440

110

0

813

708

2.0

RHA40

550

330

220

0

813

708

2.0

FA20

550

440

0

110

813

708

2.0

FA40

550

330

0

220

813

708

2.0

RHA10FA10

550

440

55

55

813

708

2.0

RHA20FA20

550

330

110

110

813

708

2.0

2.3 Testing procedures The properties of the SCC mixtures in the fresh state were tested, including density, flow-type slump or slump flow, slump flowing time required to reach 50 cm, and J-ring flow. The test procedures and evaluations were executed in accordance with the relevant ASTM standards [11]. The V-funnel flow time was determined by recording the time in seconds required for the mixture to flow through the funnel after opening the bottom plate in accordance with EFNARC standards [12]. The compressive strength development and pulse velocity (UPV) tests were performed on hardened concrete specimens. The compressive strength development were tested at the ages of 3, 7, 28, and 91 days after pouring in accordance with ASTM standards [11].

3. Results and Discussion 3.1. Properties of fresh SCC In order to maintain the controlled slump flow in the range between 67.5 to 72.5 cm diameter, SCC mixtures mixed with RHA required greater amounts of water requirement than those mixed with FA. The increase in water requirement is because of the porous structure, larger particle size, and high specific surface area of rice husk ash [2-5, 8-9]. The filling and lubricating effect of water is insufficient to offset the increased water demand resulting from the increased surface area of RHA. As shown in Table 3, the slump flow of the control SCC and mixtures containing FA were within the limits generally prescribed in concrete specifications [11-12]. The slump flow values were primarily dependent on the replacement level of RHA, and increased amounts of RHA resulted in increased both slump flow and flowing times tested by V-funnel. In contrast, increasing amounts of RHA absorbed much more water and produced a readily-crumbled SCC. This was confirmed in the V-funnel flow time results in which the 40% RHA mixture was extremely stiff, inducing

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blocking behaviour [8]. Combination of FA with RHA can decrease the required water-powder material ratio and improved the workability due to the spherical shape and fine particle size, which enhanced the packing density and reduced the flow resistance [2-4]. Increasing amounts of FA and RHA resulted in a reduction in SCC mixture density, due to these materials are lower specific gravity than OPC particles [4, 8].

Table 3. Properties of SCC mixtures in the fresh state.

Slump flow Mix

J-ring test

V-funnel Time

blocking

Density

Diameter

T50cm

Diameter

w/b

(cm)

(s)

(cm)

Control

70

4

68

RHA20

70

6

68

No

14

0.42

93

RHA40

68

7

64

Minimal

24

0.57

87

(%Control)

(s) No

7

0.26

100

FA20

70

4

70

No

8

0.28

97

FA40

72

5

68

No

10

0.30

94

RHA10FA10

70

5

70

No

12

0.36

95

RHA20FA20

70

6

69

No

20

0.49

94

3.2. Properties of hardened SCC As shown in Fig. 1 the RHA/FA SCC mixtures were lower compressive strengths than that of the SCC mixture containing OPC (control), and increased with decreasing w/b ratio at all ages. Increasing RHA and FA content resulted in lower compressive strength. SCC mixtures prepared using FA developed higher compressive strength than mixtures prepared using RHA. The increased strength was due to filling and dispersing effects as well as the availability of an increased number of nucleation and precipitation sites [2, 9].

Incorporation of RHA decreased the compressive strength due to greater porosity, leading to a higher water requirement [7-8] and increased void content [5]. Incorporation of FA and RHA blends improved the compressive strength development as the smaller particles of FA filled voids within the mixture, decreasing porosity and water demand.

90

Control RHA40 FA40 RHA20FA20

Compressive strength (MPa)

80 70

RHA20 FA20 RHA10FA10

60 50 40 30 20 10 0 0

7

14

21

28

35

42

49

56

63

Test age (days) Fig. 1. The compressive strength development of SCC mixture with/without FA/RHA.

70

77

84

91

98

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The average penetration velocities of ultrasonic pulse of the SCC mixtures are showed in Fig. 2. The velocity was dependent on the density of the internal structure of the concrete. The velocities were higher in mixtures containing FA because the fine particles filled large voids and reduced the porosity [9]. RHA mixtures had a greater number of capillary pores, and the width of C–S–H gel/pore interfacial transition zone and air-voids have attenuated the pulse propagation, dropping the velocity through the SCC specimen [5]. In general, the UPV decreased with increasing FA and RHA content [4, 8].

4. Conclusions The experimental results from the investigation of the properties of self-compacting concrete (SCC) mixtures containing OPC, untreated RHA, and FA allowed concluding remarks that: 1. Mixtures containing a combination of FA and RHA exhibited decreased water requirements and improved workability.

2. In suitable proportions, SCC mixtures containing RHA and FA can develop adequate early-age compressive strength.

RHA20FA20

91 28

Type of concrete

RHA10FA10

7 3

FA40 FA20 RHA40 RHA20 Control 1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Ultrasonic pulse velocity (km/s) Fig. 2. Ultrasonic pulse velocity of SCC mixtures.

References [1] Okamura H, M. Ouchi M. Self-compacting concrete. J Adv Concr Technol 2003;1(1):5-15.

[2] Liu M. Self-compacting concrete with different levels of pulverized fuel ash. Constr Build Mater 2010;24(7):1245–52.

[3] Wang A, Zhang C, Sun W. Fly ash effects: I. The morphological effect of fly ash. Cem Concr Res 2003;33(12):2023–29.

[4] Khatib JM. Performance of self-compacting concrete containing fly ash. Constr Build Mater 2008; 22(9):1963–71.

[5] Safiuddin Wd, West JS, Soudki KA. Hardened properties of self-consolidating high performance concrete including rice husk ash, Cem Concr Compos 2010;32(9):708-17.

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[6] Food and Agriculture Organization of the United Nations. Crop Prospects and Food Situation. FAO Corporate Document Repository. Rome; 2012.

[7] Zerbino R, Giaccio G, Isaia GC. Concrete incorporating rice-husk ash without processing. Constr build Mater 2011;25(1):371-8.

[8] Sua-iam G, Makul N. Utilization of limestone powder to improve the properties of self-compacting concrete incorporating high volumes of untreated rice husk ash as fine aggregate. Constr Build Mater 2013;38:455-64.

[9] Chindaprasirt P, Rukzon S. Strength, porosity and corrosion resistance of ternary blend Portland cement, rice husk ash and fly ash mortar, Constr Build Mater 2008;22(8):1601–6.

[10] American Society for Testing and Material. Annual Book of ASTM Standard Vol. 4.01. Philadelphia; 2011.

[11] American Society for Testing and Material, Annual Book of ASTM Standard Vol. 4.02. Philadelphia; 2009.

[12] EFNARC. Specification and guidelines for self-compacting concrete, Surrey; 2002.

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