The Use of Rice Husk Ash (RHA) in Preparation of Fly Ash ... · husk ash (RHA) so it is of interest to replace nano-silica. When rice husk (RH) was burned to eliminate carbonaceous

The 2018 World Congress on Advances in Civil, Environmental, & Materials Research (ACEM18) Songdo Convensia, Incheon, Korea, August 27 - 31, 2018

The Use of Rice Husk Ash (RHA) in Preparation of Fly Ash-Based Geopolymer

*Suthee Wattanasiriwech1), Krissanapat Yomthong2), and Darunee

Wattanasiriwech3)

1), 2), 3) Materials for Energy and Environment (MEE) Research Group,

School of Science, Mae Fah Luang University, 57100, Thailand 1) [email protected]

ABSTRACT

This research was aimed to study the use of three types of rice husk ash (RHA) by replacement the fly ash (FA) in preparation of fly ash based geopolymer. The replacement in the content of 0%, 3%, 5% and 10% by weight was chosen. The RHA used in this study were obtained from (i) the rice drying-process (ii), (iii) in house by burning RH at 600°C and 700 °C (coded as RHA600 and RHA700) respectively. Liquid sodium silicate (LSS) and sodium hydroxide (SH) solution were used as activating agents. The weight ratio of LSS to SH was 1.0 and total liquid to solid was 0.6. The geopolymer prepared without RHA (the control) gave an average compressive strength of 35.91±3.30 MPa. The highest compressive strength value of 42.52±4.86 MPa was obtained at 3%

replacement using RHA700C, while Furthermore, density, porosity, phase development (XRD) and thermal behavior (TGA) were examined. Keywords: geopolymer, fly ash, rice husk ash, compressive strength 1. INTRODUCTION Approximately, one ton of carbon dioxide (CO2) was released to atmosphere per one ton of Portland cement (PC) production. This PC production also consumed a significant high amount of natural resources and it is contributes to greenhouse problem [1]. To finding a more environmental friendly material to replace PC is a critical challenge for scientist. That material should have properties similar to PC. Therefore, geopolymer is the most interesting to replace the PC because it gave properties nearly to PC. Geopolymer can be synthesized from rich silica and alumina source materials. The rich silica and alumina source materials are usually comprised of fly ash (FA) from coal burning process, thermally activated clay and slag from blast furnace burning process [2, 3]. The silica and alumina are activated by an alkaline activator that consists

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of alkali silicate and alkali hydroxide to produce aluminosilicate gel [2, 4]. The curing temperature of geopolymer can be cured at room temperature6. The reaction between rich silica and alumina source materials and alkali activated solution is called geopolymerization [1]. Geopolymer possess excellent mechanical properties, fire resistance, acid resistance and can be alternate PC [4, 5]. FA is a useful material for producing geopolymer because of its high alumina and silica contents. Use of FA as a precursor for geopolymer production could also offer benefits on waste management [1, 4]. The mostly used alkali activation solutions are the sodium hydroxide (NaOH) and sodiumsilicate (Na2SiO3) because it is low cost and viable [6]. Phoo-ngernkham et al. and Khater et al. tried to improve properties of geopolymer by adding nano-silica and nano-alumina. The results showed that the mechanical properties of geopolymer were enhanced [3,7]. Notwithstanding, nano-particle (SiO2 and Al2O3) is expensive. Alternative material containing high amount of silica is rice husk ash (RHA) so it is of interest to replace nano-silica. When rice husk (RH) was burned to eliminate carbonaceous compound at 600°C and 700°C, high purity silica could be obtained. This silica is porous and has high abundant Si-OH group [8, 9]. The use of purified rice husk ash (RHA) containing a high amount of silica showed a positive effect on mechanical properties of geopolymer. However, preparation of high purity RHA was too costly to be commercially viable. Partially burned RHA, an abundant by-product from rice husk (RH) fired hot air generator, could be a more favorable choice. This research thus aims to explore the use of partially burned RHA in geopolymer formation to improve the mechanical property. The replacement of FA with RHA in the content of 0%, 3%, 5% and 10% by weight were chosen. 2. MATERIALS AND METHODS 2.1. Materials FA was received from Mea Moh power plant, Lampang, Thailand. The activated alkali liquids used were 12M NaOH and commercial grade liquid sodium silicate (LSS). The chemical compositions of LSS was 16.24% Na2O, 34.73% SiO2 and 49.03% H2O. The weight ratio of SS /SH used was 1.0 and ratio of total liquid to solid (L/S) used was 0.6. Three types of RHA were used in this experiment; namely RHAR, RHA600, RHA700. RHAR was received from a rice-drying process place without further modification. RHA600 and RHA700 was derived from in house burning of RH in a muffle furnace

(Carbolite/ CWF13/13/2416; Scientific Promotion) at 600 C and 700 C for 4 h respectively. FA was milled using ball milling for 10 min. RHAs were hand grounded with a mortar for 5 min. Particle sizes of FA, RHAR, RHA600 and RHA700 after milling and grinding were determined by Particle size distribution analyzer (Malvern Instrument/Masterzer 2000). 2.2. Mixing and Activated temperature curing The LSS and SH was hand mixed together for 2 min and used as a liquid solution. Subsequently, RHA was added into liquid solution at the content of 0%, 3%, 5% and 10% FA replacement and mixed for 2 min. FA was then added and mixed together for 1 min. The resulting ratio of SiO2/Al2O3 is shown in Table 1. Finally, precursor paste

https://www.google.co.th/search?q=rice+husk+fired+hot+air+generator&espv=2&biw=1745&bih=814&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjP3tH-pYTMAhVosYMKHWFSA6MQsAQIIg


was poured into PVC mold. The samples were cure at 90 C for 24 h under water saturated atmosphere. This process is activated the geopolymer paste to harden. Then,

it was transferred to curing at 40 C for 72 h under water saturated atmosphere.

Afterwards, geopolymer paste was cured at 40 C for 72 h under open air. 2.3. Characterization The universal testing machine (INSTRON 5566) was used to measure the compressive strength of samples at 7th day. The cylindrical samples were polished on P320 abrasive paper with a rotational speed 200 rpm. The measurement was performed according to ASTM C39-04a. The loading speed was set at 1.0 mm/min and maximum load used was 10.0 kN. This testing method was set a specimen protect before during test at 0.5 MPa. The average compressive strength was averaged from five samples.


Table 1. Weight ratio of FA and RHA and the calculated SiO2/Al2O3 ratio

Code Raw material SiO2/Al2O3 ratio

Control 100% FA 2.83

3RHAR 3RHA600 3RHA700

97%FA + 3%RHAR 3.01

97%FA + 3%RHA600 3.05

97%FA +3% RHA700 3.06


95%FA + 5%RHAR 3.13

95%FA + 5%RHA600 3.20

95%FA + 5%RHA700 3.22


90%FA + 10%RHAR 3.47

90%FA + 10%RHA600 3.61

90%FA + 10%RHA700 3.66

Bulk, apparent density and porosity of the 7th day cured geopolymer was according to ASTM C642-06. Phase development was investigated using an X-ray Diffraction

(PANanalytical, X’PertPRO).The XRD scans were operated at 5 to 70 2, 0.0008 degree/step. The speed of XRD scans was set at 20 s/step. Thermogravimetric analysis (MettlerToledo/851e) was performed to investigate mass change of geopolymers up on heating. The samples approximately 20 – 25 mg

was investigated in an alumina pan. The temperature range used was 20 – 1,200 C

and heating rate used was10 C/min. Nitrogen gas was used in this experiment and used flow rate was 120 ml/min. 3. RESULTS & DISCUSSION 3.1. Chracterisation of the starting materials The chemical compositions of FA, RHAR, RHA600 and RHA700 is shown in Table 2. The result showed that burning of RHA700 was relatively complete so only minor weight loss was observed. Phase analysis of the FA using an XRD technique shoed that there existed 5 crystalline phase of anhydrite (CaSO4), quartz (SiO2), magnesioferrite (Fe2MgO4), hematite (Fe2O3), lime (CaO) .

Table 2. Chemical compositions of FA, RHAR, RHA600 and RHA700 as analysed using an X-ray fluorescence. Noted that data for RHA600 and RHA700 was received

from ref[8].

Material Chemicals Compositions (%weight)

SiO2 Al2O3 Fe2O3 CaO K2O SO3 LOI

FA 29.765 14.248 19.074 24.545 2.309 9.226 0.281

RHAR 71.410 - 0.090 0.720 0.940 0.490 25.370

RHA600 89.850 - 0.060 0.340 1.930 0.260 7.410

RHA700 95.590 - 0.250 0.940 1.530 0.510 0.990


Particle size distribution result is for the starting materials are shown in Table 3.

Table 3. Particle size distribution of FA and RHA

Material D10 (µm)

D50 (µm)

D90 (µm)

Mean (µm)

FA 2.124 19.26 62.747 26.825

RHAR 6.07 40.156 115.227 58.727

RHA600 4.79 27.902 78.456 35.501

RHA700 7.212 40.595 95.223 46.414

Figure 1. XRD spectrum of the FA used in this research

3.2. Thermal behavior and relative weight loss Thermograms of the 3RHA700 is shown in Fig. 2. The analysis showed a large

decrease of mass around 13% at 120 C. Elimbi9 reported that there were 3 types of water , namely adsorbed water, interstitial water, and hydroxyl water, existing in

geopolymer . Elimination of these water occurred between 50-125 C, 125-250 C and

250 C and 750 C respectively. However, in our present result, only elimination of adsorbed water was observed.

Figure 2. TGA/DTG for the 3RHA700


3.3. Phase analysis The XRD patterns of control and 3RHA700 are shown in Fig. 3 The broad hump

observed approximately between 25 - 35 2 was according to the presence of the glassy phase. The dominant crystalline phases obsedved in control was quartz (SiO2), Calcium Silicate Hydrate (CaSiO3.xH2O) and Lazurite (Na8.56(Al6Si6O24)(SO4)1.56 S0.44)). The phases observed in the XRD spectrum for 3RHA700 were relatively similar to those of the control. It was noted that intensity of quartz was increased while that of lauzite was decreased in the 3RHA700 as compared to the control.

Figure 3. XRD patterns of the control and the 3RHA700 (CSH: Calcium Silicate Hydrate (CaSiO3.xH2O)), L: Lazurite (Na8.56(Al6Si6O24)(SO4)1.56 S0.44)).

3.4. Bulk density, Apparent density and Porosity While bulk density did not show great variation among the sample types, apparent density was obviously different. The apparent density was enhanced when 3% of RHA was incorporated regardless of the type of RHA. Futher increasing RHA content to 5% resulted in a decrease of the apparent density and finally decreased to lower than the control in the 5% replacement.

0 10 20 30 40 50 60 70 80

Inte

nsi

ty (

Co

un

ts)

Position (◦2Theta)

Control

3%RHA700CL

Q L L M L F L

L

L L Q

CS

H L M

Q


Table 4. Bulk density, apparent density and porosity of the geopolymers prepared with various types and contents of RHA.

System Bulk

density(g/cm3) SD

Apparent Density (g/cm3)

SD

Control 1.90 0.15 2.28 0.21

3RHAR 1.96 0.01 2.41 0.01

3RHA600 1.98 0.02 2.38 0.00

3RHA700 1.96 0.02 2.36 0.01

5RHAR 1.89 0.04 2.28 0.04

5RHA600 1.91 0.02 2.32 0.06

5RHA700 1.91 0.03 2.32 0.04

10RHAR 1.88 0.10 2.25 0.14

10RHA600 1.86 0.00 2.15 0.01

10RHA700 1.93 0.07 2.25 0.10

3.5. Compressive strength The compressive strength for cured geopolymers was shown in Fig. 4. Compressive strength of the control was 35.91±3.30 MPa. Replacement FA with RHA in all types could obviously improve the compressive strength of the geopolymers with the increasing trend according to the SiO2 content. The highest compressive strength of 42.52±4.86 MPa was found at 3% replacement with RHA700C. Increasing the replacement content damaged the compressive strength dramatically. Phoo-ngernkham6 reported that addition of SiO2 could induce formation of calcium silicate hydrate (CSH) or calcium aluminosilicate hydrate (CASH) and sodium aluminosilicate hydrate (NASH) in high alkali and high calcium contents leading to enhanced strength. Further increasing RHA contents resulted in low workability and difficulty in processing so compressive strength was reduced.


Figure 4. Compressive strength of FA-based geopolymers prepared with various

RHA types and replacement contents. 4. CONCLUSION Preparation of geopolymer with replacement of FA with various types and contents of RHA was found to give interesting results. The result showed that the optimum content of RHA used should not be greater than 3% replacement. At this concentration, improvement of compressive strength with the SiO2 content in RHA was observed. The enhanced compressive strength in the 3% replacement was suggested to be due to the increased apparent density and the better geopolymerisation of nanosilica in RHA. Further increasing RHA content resulted in very viscous mixture, workability and flowabilty became the key factors influencing the compressive strength. 5. REFERENCES N. Van Chanh, B. D. Trung, and D. Van Tuan, “Recent Research Geopolymer Concrete,” in The 3rd ACF International Conf. ACF/VCA, Vietnam, 2008, pp. 11-13.

J. L Provis, and J. S. J. Van Deventer, “Geopolymers: structures, processing, properties and industrial applications,” in Woodhead Publishing Series in Civil and Structural Engineering, 2009

T. Phoo-ngernkham, P. Chindaprasirt, V. Sata, S. Hanjitsuwan, and S. Hatanaka, “The effect of adding nano-SiO 2 and nano-Al 2 O 3 on properties of high calcium fly ash geopolymer cured at ambient temperature,” in Materials & Design, vol. 55, pp. 58-65, 2014.

A. M. Al Bakria, H. Kamarudin, M. BinHussain, I. K. Nizar, Y. Zarina, and A. R. Rafiza, “The effect of curing temperature on physical and chemical properties of geopolymers,” in Physics Procedia, vol. 22, pp. 286-291, 2011.

J. G. S. Van Jaarsveld, J. S. J. Van Deventer, and G. C. Lukey, “The effect of composition and temperature on the properties of fly ash-and kaolinite-based geopolymers,” in Chemical Engineering Journal, vol. 89(1), pp. 63-73, 2002.

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35

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50

control RHAR RHA600 RHA700

Co

mp

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ive

Str

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th (

MP

a)

Control

3% Replacement

5% Repalcement

10% Repalcement


G. Görhan and G. Kürklü, “The influence of the NaOH solution on the properties of the fly ash-based geopolymer mortar cured at different temperatures,” in Composites part b: engineering, vol. 58, pp. 371-377, 2014.

H. M. Khater, B. A. El-Sabbagh, M. Fanny, M. Ezzat, and M. Lottfy, “Effect of nano-silica on alkali activated water-cooled slag geopolymer,” in Proceedings of the Second International Conference on Microstructural-related Durability of Cementitious Composites, Amsterdam, the Netherlands, vol. 1113, 2012.

D. Wattanasiriwech, N. Polpuak, P. Danthaisong, and S. Wattanasiriwech, “Use of rice husk ash for quartz substitution in stoneware glazes,” in Journal of Scientific and Industrial Research, vol. 67(6), pp. 455, 2008.

L. Xiong, E. H. Sekiya, P. Sujaridworakun, S. Wada, and K. Saito, “Burning temperature dependence of rice husk ashes in structure and property,” in Journal of Metals, Materials and Minerals, vol. 19(2), pp. 95-99, 2009.

A. Elimbi, H. K. Tchakoute, M. Kondoh, and J. D. Manga, “Thermal behavior and characteristics of fired geopolymers produced from local Cameroonian metakaolin,” in Ceramics International, vol. 40(3), pp. 4515-4520, 2014.

P. S. W. M. Duxson, S. W. Mallicoat, G. C. Lukey, W. M. Kriven, and J. S. J. Van Deventer, “The effect of alkali and Si/Al ratio on the development of mechanical properties of metakaolin-based geopolymers,” in Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 292(1), pp. 8-20, 2007.

6. ACKNOWLEDGEMENT Financial support from Mea Fah Luang University is highly appreciated.

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The Use of Rice Husk Ash (RHA) in Preparation of Fly Ash ... · husk ash (RHA) so it is of interest to replace nano-silica. When rice husk (RH) was burned to eliminate carbonaceous