Embed Size (px)
Citation preview
Construction and Building Materials 71 (2014) 210–215
Contents lists available at ScienceDirect
Construction and Building Materials
journal homepage: www.elsevier .com/locate /conbui ldmat
Technical Note
Strength of sustainable non-bearing masonry units manufacturedfrom calcium carbide residue and fly ash
http://dx.doi.org/10.1016/j.conbuildmat.2014.08.0330950-0618/� 2014 Elsevier Ltd. All rights reserved.
⇑ Corresponding authors. Address: School of Civil Engineering, Suranaree Uni-versity of Technology, 111 University Avenue Muang District, Nakhon Ratchasima30000, Thailand. Tel.: +66 44224322; fax: +66 44224607.
E-mail addresses: [email protected] (S. Horpibulsuk), [email protected] (A.Chinkulkijniwat).
Suksun Horpibulsuk a,⇑, Varagorn Munsrakest a,b, Artit Udomchai a, Avirut Chinkulkijniwat a,⇑,Arul Arulrajah c
a Suranaree University of Technology, Nakhon Ratchasima 30000, Thailandb Department of Public Works and Town & Country Planning, Thailandc Swinburne University of Technology, Melbourne, Australia
h i g h l i g h t s
� Calcium Carbide Residue (CCR) and fly ash (FA) as cementing agent.� Sustainable CCR–FA non-bearing masonry units.� Role of water/binder ratio, CCR/FA ratio and curing time on strength.� Cost analysis for manufacture of CCR–FA masonry units.
a r t i c l e i n f o
Article history:Received 7 May 2014Received in revised form 14 August 2014Accepted 24 August 2014
Keywords:StrengthMasonry unitCalcium carbide residueFly ash
a b s t r a c t
This paper aims to study the viability of using Calcium Carbide Residue (CCR) and fly ash (FA) as acementing agent (binder) for the manufacture of non-bearing masonry units without Portland Cement(PC). CCR and FA are waste products from acetylene gas factories and power plants, respectively. The testsamples were made up at a binder to stone dust ratio of 1:8 by weight. The studied water to binder (W/B)ratios were 0.50, 0.75 and 1.00, and the CCR/FA ratios were 80:20, 60:40 and 40:60. The W/B ratio of 0.75and CCR/FA ratio of 40:60 were found to be an optimal mix proportion providing the highest both unitweight and strength. The higher CCR/FA ratios provide lower strength values because the silica and alu-mina in FA are insufficient to react with abundant Ca(OH)2 in the CCR for the pozzolanic reaction. Theoptimal mix proportion provides the strength of the CCR–FA based material greater than 20 MPa, whichis acceptable for non-bearing masonry unit. The cost analysis showed that the material costs of the CCR–FA masonry unit were 40% lower than those of the PC masonry unit. Besides the cost effectiveness, theoutcome of this research would divert significant quantity of CCR from landfills and considerably reducecarbon emissions due to PC production.
� 2014 Elsevier Ltd. All rights reserved.
1. Introduction
Portland Cement (PC) based masonry unit is an extensively usedconstruction and building material worldwide. The high unit costand energy intensive process for the production of PC are howeverthe predominant driving forces for the constant need withinthe industry to seek alternative cementitious additives with lowcarbon dioxide release. Production of 1 kg of PC consumes
approximately 1.5 kWh of energy and releases about 1 kg of CO2
to the atmosphere [1–3].In recent years, there has been an environmental push world-
wide to continually seek new reuse applications for various wastematerials inclusive of demolition wastes [4–6], municipal solidwaste [7–9], commercial and industrial wastes [10–16]. Wastematerials are increasingly being implemented in various projectsin pavement and concrete applications [17–22].
A waste Ca(OH)2 rich material, Calcium Carbide Residue (CCR),can be utilized together with waste pozzolanic materials such asfly ash, and biomass ash to develop a cementing agent [15,23].CCR is a by-product of acetylene (C2H2) production processthrough the hydrolysis of calcium carbide (CaC2). Its productionis described by the following equation [24]:
Fig. 1. Grain size distribution of stone dust, FA and CCR.
Table 1Chemical properties of FA, CCR, hydrated lime and cement.
Chemical composition(%)
FA CCR Hydratedlime
Portlandcement
CaO 11.30 70.78 90.13 65.41SiO2 39.18 6.49 1.29 20.90Al2O3 22.64 2.55 0.24 4.76Fe2O3 15.45 3.25 0.49 3.41MgO 1.69 0.69 0.22 1.25SO3 4.29 0.66 0.86 2.71Na2O 1.81 – – 0.24K2O 2.02 7.93 3.3 0.35Loss of ignition, LOI 1.61 7.65 3.48 0.97
S. Horpibulsuk et al. / Construction and Building Materials 71 (2014) 210–215 211
CaC2 þ 2H2O! C2H2 þ CaðOHÞ2 ð1Þ
From Eq. (1), it is seen that 64 g of calcium carbide (CaC2) pro-vides 26 g of acetylene gas (C2H2) and 74 g of CCR in terms ofCa(OH)2. The CCR is generated as an aqueous slurry and is com-posed essentially of calcium hydroxide (Ca(OH)2) with minor partsof calcium carbonate (CaCO3), unreacted carbon and silicates[24,25]. The characteristics of CCR are influenced by the processingparameters during acetylene fabrication. Presently, the demand ofCaC2 for producing acetylene gas in Thailand is 18,500 tons/year.This provides 21,500 tons/year of CCR and the demand is continu-ously increasing each year.
Fly ash (FA) is a pozzolanic waste material extracted from fluegases of furnaces fried with coal at electric power plants. In Thai-land, a major source of FA is the Mae Moh electricity power plant,Lumpang. Lignite is used as a raw material for the electricity gen-eration. The sum of major components in FA (SiO2, Al2O3 andFe2O3) is between 72% and 80%. Its generation is far in excess ofutilization. FA is commonly used together with PC for civil engi-neering works [21,26,27]. Due to its lower early strength of CCRand FA compared to Portland cement, the application of CCR andFA is limited previously to pavement and geotechnical application[14–18,23,24,28–30]. The innovative application of CCR and FA forthe manufacture of building materials is however possible for lowstrength requirement such as masonry units. This investigation isvery limited and needs to be addressed due to a large demand ofconstruction activities. The application of the CCR with FA as a sus-tainable cementing agent to develop non-bearing masonry units inthis paper is thus novel and innovative particularly in the Asia-Pacific region. Stone dust is generally used as a raw material forthe manufacture of masonry units. The stone dust is obtained fromopen-air dumpsite of marble and limestone plants. The in situwater content ranges from 1% to 2%. The dried stone dust was com-posed of individual particles and lumps. The lumps resulted fromthe fragmentation of compacted slurry slabs obtained in the waterrecovering operations held at the processing plant.
This paper aims to study the possibility of using two wastematerials (CCR and FA) as a sustainable cementing agent for man-ufacturing masonry units without PC. The compressive strength ofthe CCR–FA based material will be examined to ascertain it as non-bearing masonry units. The compressive strength requirement fornon-bearing masonry units is 20 MPa according to the ThailandIndustrial Standard (TIS). Only short-term (<14 day) strength isinvestigated because the masonry units are generally on salewithin 14 days of curing. Based on the strength analysis, the opti-mal mix proportion is suggested. Subsequently, the cost analysisbased on this suggested mix is performed to compare the produc-tion costs between PC masonry units and CCR–FA masonry units.Both strength data and cost analysis illustrate the advantage ofusing CCR and FA as a binder in terms of engineering and econom-ical viewpoints. In addition to strength test, water absorption,durability and heavy metal leaching tests are required and neededfurther investigation. The outcome of this research would divertsignificant quantity of CCR from landfills and considerably reducecarbon emissions due to PC production.
2. Materials and methods
2.1. Materials
Stone dust from Saraburee province in Thailand, CCR from the Sai 5 Gas ProductCo., Ltd, FA from the Mae Moh power plant in the north of Thailand, and tap waterwere used in this study. The stone dust was passed through 19 mm sieve to removecoarser particles. The grain size distribution of the stone dust is shown in Fig. 1 andthe specific gravity is 2.64. Both the CCR and FA were passed through sieve No. 4(4.75 mm) and there was not any particles remaining on the sieve. In other words,the original CCR and FA were used directly as a cementing agent. The specific grav-ity values are 2.32 and 2.39, respectively. Table 1 shows the chemical composition
of both FA and CCR compared with that of a hydrated lime and PC. Total amount ofthe major components (SiO2, Al2O3 and Fe2O3) in FA are 81.48%. The chemical com-position (Table 1) shows the CaO contents of 90.13%, 70.78%, and 65.41% forhydrated lime, CCR and PC, respectively. This result is in agreement with the X-ray diffraction (XRD) pattern (vide Fig. 2). The XRD pattern of the CCR is similarto that of the hydrated lime, showing the Ca(OH)2 as a main composition. TheCa(OH)2 contents are about 96.5% and 76.7% for hydrated lime and CCR, respec-tively. The high Ca(OH)2 and CaO contents of the CCR indicate that it can react witha pozzolanic material and produce a cementitious material. The grain size distribu-tion curves of tested FA and CCR are also shown in Fig. 1. The curves were obtainedfrom the laser particle size analysis. The average grain size (D50) of FA and CCR are0.0035 and 0.01 mm, respectively. Scanning electron microscope (SEM) photos ofFA and CCR are shown in Fig. 3. From the grain size distribution and the SEM photos,it is found that the stone dust and CCR particles are larger than the FA particles. TheCCR is irregular in shape while the FA is spherical.
2.2. Methodology
The stone dust was mixed with different water to binder (W/B) and CCR/FAratios. The studied W/B ratios were 0.50, 0.75 and 1.00, and the studied CCR/FAratios were 80:20, 60:40 and 40:60. The binder/stone dust ratio was fixed at 1:8in this study. The mixture of water, CCR, FA and stone dust was thoroughly mixingfor 15 min and transferred to a cube mold with a dimension of 150 � 150 � 150mm3. The mold was then vibrated for 15 min to follow the tradition method ofmanufacturing stone dust non-bearing units. After 24 h, the samples were disman-tled from the mold, wrapped in vinyl bags and stored in a chamber of constant tem-perature (25 ± 2 �C) and humidity (45 ± 2%). Uniaxial compression test wasundertaken on the samples after 7 and 14 days of curing. Only 7-day and 14-daystrengths were measured because in practice masonry units are on sale for con-struction works within 14 days of curing. Because the chemical reaction betweenCCR and FA is pozzolanic, the long-term strength is higher than the measured 14-day strength. According to ASTM D 2166, a rate of vertical displacement is between0.5% and 2.0%/min for uniaxial test. The rate of vertical displacement was then fixedat 1 mm/min (0.7%/min). For each curing time, W/B and CCR/FA ratios, at least fivesamples were tested under the same condition to check for consistency of the test.In most cases, the results under the same testing condition were reproducible withlow standard deviation, SD (SD=�x < 10%, where �x is mean strength value). Table 2summarizes the mix proportions of the tested samples.
Fig. 2. XRD pattern of CCR compared with hydrate lime.
Fig. 3. SEM photos of CCR and FA.
Table 2Mix proportion for CCR–FA-stone dust sample.
W/B CCR/FA Mix proportion
CCR (g) FA (g) Stone dust (g) Water (g)
0.5 80:20 80 20 800 5060:40 60 40 800 5040:60 40 60 800 50
0.75 80:20 80 20 800 7560:40 60 40 800 7540:60 40 60 800 75
1.00 80:20 80 20 800 10060:40 60 40 800 10040:60 40 60 800 100
Fig. 4. Unit weight and CCR/FA ratio relationship of the samples after 7 days ofcuring.
212 S. Horpibulsuk et al. / Construction and Building Materials 71 (2014) 210–215
3. Results and discussion
Figs. 4 and 5 show the unit weight of samples with CCR/FAratios of 80:20, 60:40 and 40:60, and W/B ratios of 0.5, 0.75 and1.0 after 7 and 14 days of curing. The unit weight depends on the
Fig. 5. Unit weight and CCR/FA ratio relationship of the samples after 14 days ofcuring.
Fig. 7. Strength and CCR/FA ratio relationship of the samples after 14 days ofcuring.
Fig. 8. Strength development with curing time for the samples with different mixproportions.
S. Horpibulsuk et al. / Construction and Building Materials 71 (2014) 210–215 213
CCR/FA and W/B ratios. The unit weight of cubic samples increasesas the CCR/FA ratio decreases from 80:20 to 40:60. The unit weightof cubic samples increases by about 5.1% as the ratio of CCR/FAdecreases from 80:20 to 40:60, while the difference in specificgravity between CCR and FA is only 0.07. The is because FA particleis spherical in shape (Fig. 3); i.e, the increase in this spherical FAincreases the workability and compact-ability of the CCR–FA-stonedust mixture as also reported by Horpibuksuk et al. [30].
Figs. 4 and 5 also show that with increasing W/B, the unitweight of the mixture increases up to the optimal W/B value andthen decreases. The highest unit weight is at optimal W/B ratioof 0.75 for all the CCR/FA ratios. Prior to the optimal value, thewater lubricates the aggregates (CCR, FA and stone dust particles).This sufficient water at optimal W/B makes stone dust, CCR and FAparticles slip over each other and move into a densely packed state.The excessive water (W/B is greater than optimal value) enters thepore space and leads to loose packing. As such, the mixture of W/Bof 1.0 shows lower unit weight than the mixture of W/B of 0.75.This phenomena has been proved by Horpibulsuk et al. [30–32]using Mercury Intrusion Porosimetry (MIP), Scanning ElectronMicroscopy (SEM) and Thermal Gravity Analysis (TGA). Over curingperiod (from 7 to 14 days of curing), the unit weight tends toincrease but with a small magnitude. The increase in unit weightis due to the growth of cementitious products filling the pore space[30].
Figs. 6 and 7 show the strength development in the sampleswith different CCR/FA and W/B ratios after 7 and 14 days ofcuring, respectively. The strength development for a particularCCR/FA ratio is attributed to two main factors; densification andcementitious products from pozzolanic reaction. From Figs. 4 to7, the samples with W/B ratio of 0.75 provide the highest unit
Fig. 6. Strength and CCR/FA ratio relationship of the samples after 7 days of curing.
weight (densest) and compressive strength (cementitious prod-ucts). The lower W/B ratio is insufficient for the pozzolanic reactionwhile the higher W/B ratio increases the void space per binder vol-ume [33,34]. Even though the chemical reaction of the samples onthe dry side of optimum W/B is not complete, the matric suction(the difference between pore air pressure and pore water pressure)contributes the strength to the samples [31,35]. Consequently, thestrength of the samples on the dry side of the optimum W/B is lar-ger than that on the wet side of the optimum W/B; i.e. thestrengths of the samples with W/B ratio of 0.5 is greater than thosewith W/B ratio of 1.0.
Besides the optimum W/B ratio, the CCR/FA ratio is the othermain factor controlling the strength development. The most suit-able CCR/FA ratio that provides the highest unit weight andstrength is 40:60. Due to smaller particles, the FA particles fill upthe pore space between the CCR and stone dust. Hence, the unitweight increases as the FA replacement increases. In addition,the amount of CCR for this CCR/FA ratio is appropriate to react withthe pozzolanic materials (SiO2 and Al2O3) in FA. For large input ofCCR, the nonreactive Ca(OH)2 (free lime) is remained in the mix-ture and insignificantly improves the strength because the Ca(OH)2
solely is not reactive with water (no chemical reaction). This expla-nation has been verified based on TGA and SEM analysis by Horpi-bulsuk et al. [15]. The higher input of CCR (CCR/FA values of 60:40and 80:20) is thus not recommended. Based on a linear regressionanalysis (Figs. 6 and 7), the relationships between 7-day strength(q7) and 14-day strength (q14) versus CCR/FA ratio are representedby linear functions as follows:
Table 3Cost analysis for manufacturing CCR and FA concrete block and Portland cement concrete block.
Item Amount Unit Cost estimate
Unit cost (baht/ kg) (USD$/kg) Cost (baht) (USD$)
Portland cement concrete bock1 Portland cement 0.81 kg. 2.40 (0.08) 1.95 (0.07)2 Stone dust 6.50 kg. 0.26 (0.01) 1.69 (0.06)
Total cost per a block 3.64 (0.12)
CCR and FA concrete block1 Calcium carbide residue 0.33 kg. – –2 Fly ash 0.49 kg. 1.00 (0.03) 0.49 (0.02)3 Stone dust 6.50 kg. 0.26 (0.01) 1.69 (0.06)
Total cost per a block 2.18 (0.07)Cost difference 1.46 (0.05)
214 S. Horpibulsuk et al. / Construction and Building Materials 71 (2014) 210–215
q7 ¼ 144:7ðCCR=FAÞ þ 107:2 for W=B ¼ 0:5 ð2Þ
q7 ¼ 146:8ðCCR=FAÞ þ 286:5 for W=B ¼ 0:75 ð3Þ
q7 ¼ 65:8ðCCR=FAÞ þ 127:8 for W=B ¼ 1:0 ð4Þ
q14 ¼ 254:8ðCCR=FAÞ þ 277:2 for W=B ¼ 0:5 ð5Þ
q14 ¼ 449:5ðCCR=FAÞ þ 154:6 for W=B ¼ 0:75 ð6Þ
q14 ¼ 112:9ðCCR=FAÞ þ 257:2 for W=B ¼ 1:0 ð7Þ
where the degrees of correlation are greater than 0.972.Fig. 8 shows the strength development with time of the samples
with different mix proportions. The strength tends to increaseseven after 14 days of curing. The rate of strength developmentbetween 7 and 14 days of curing time is essentially the same forall samples. The q14/q7 ratio, where q14 is the 14-day strengthand q7 is the 7-day strength, is about 2.0. A regression analysis ofthe test data reveals that the relationship between strength devel-opment with time is represented by logarithm function for differ-ent mix proportions (Fig. 8).
qD
q7¼ 0:919 ln Dþ 0:080 7days < D < 14 days ð8Þ
where qD is the strength at D days of curing and the degree of cor-relation is 0.98. Using Eq. (8), the strengths at different CCR/FAratios between 80:20 and 40:60 and at different curing timesbetween 7 and 14 days can simply be determined once q7 is known,which can be approximated using Eqs. (3)–(5) for W/B ratios of 0.5.0.75 and 1.0.
It is evident that the mixture of CCR and FA can be used as a bin-der for the manufacture of masonry units and the optimal CCR/FAand W/B ratios are found to be 40:60 and 0.75, respectively. At thisoptimal mix proportion, the 14-day strength meets the require-ment by TIS (greater than 20 MPa) for non-bearing masonry units.Table 3 summarizes the production costs of CCR–FA masonry unitand PC masonry unit. The binder/stone dust was 1:8 for bothmasonry units and the CCR/FA value was 40:60 for the CCR–FAmasonry unit in this cost analysis. Only the material cost is usedin the analysis because the manufacturing cost (workmanshipand manufacturing process) is identical for both CCR–FA and PCmasonry units. The material unit cost for the CCR–FA masonryunits is 2.18 baht (USD$ 0.07) while it is 3.64 baht (USD$ 0.12)for the PC masonry unit. In other words, the material costs of theCCR–FA masonry units are 40% lower than those of the PC masonryunits. The application of these two waste materials as a cementingagent for the manufacture of non-bearing masonry units isuseful in terms of engineering, economical and environmentalperspectives.
4. Conclusions
The viability of using two waste materials (CCR and FA) as acementing agent (binder) for the manufacture of masonry unitsis investigated in this paper. The chemical composition and theXRD pattern of CCR are similar to those of the hydrated lime.CCR contains very high Ca(OH)2 of 76.7% while the FA contains veryhigh amount of SiO2, Al2O3 and Fe2O3 of 81.4%. As such, the mixtureof CCR and FA is suitable as a sustainable cementing agent. For thebinder/stone dust ratio of 1:8, the optimal mix proportion, whichprovides the densest packing and the most appropriate pozzolanicreaction, is CCR/FA and W/B values of 40:60 and 0.75. The 14-daystrength of CCR–FA based material at the optimal mix proportionmeets the requirement by TIS for non-bearing masonry units.The production costs of the CCR–FA masonry units are 40% lowerthan those of the PC masonry units. Besides being cost effective,the outcome of this research would divert significant quantity ofCCR from landfills and considerably reduce carbon emissions dueto PC production.
Acknowledgements
This research was supported by the Thailand Research Fundunder the TRF Senior Research Scholar program Grant No.RTA5680002. The financial support from the Higher EducationResearch Promotion and National Research University Project ofThailand, Office of Higher Education Commission as well as theassistance for the use of facilities and equipment from SuranareeUniversity of Technology are also very much appreciated. Theauthors appreciate the excellent reviewers’ comments, which sig-nificantly improve the quality of this paper.
References
[1] Malhotra VM. Concrete technology for a sustainable development in the 21stcentury. E&FN Spon; 2000.
[2] Venkatarama Reddy B, Jagadish K. Embodied energy of common andalternative building materials and technologies. Energy and Buildings2003;35(2):129–37.
[3] Davidovits J, Davidovics M. Geopolymer: room-temperature ceramic matrixfor composites. In: Proceedings of the 12th annual conference on compositesand advanced ceramic materials: ceramic engineering and scienceproceedings. John Wiley & Sons, Inc.; 2008. p. 835–41.
[4] Disfani MM, Arulrajah A, Haghighi H, Mohammadinia A, Horpibulsuk S.Flexural beam fatigue strength evaluation of crushed brick as a supplementarymaterial in cement stabilized recycled concrete aggregates. Constr Build Mater2014;68:667–76.
[5] Arulrajah A, Disfani MM, Horpibulsuk S, Suksiripattanapong C, Prongmanee N.Physical properties and shear strength response of recycled construction anddemolition materials in unbound pavement base/subbase pavement. ConstrBuild Mater 2014;58:245–57.
[6] Rahman MA, Imteaz M, Arulrajah A, Disfani MM. Suitability of recycledconstruction and demolition aggregates as alternative pipe backfillingmaterials. J Clean Product 2014;66:75–84.
S. Horpibulsuk et al. / Construction and Building Materials 71 (2014) 210–215 215
[7] Zekkos DP, Bray JD, Kavazanjian JrE, Matasovic N, Rathje EM, Riemer MF. Unitweight of municipal solid waste. J Geotech Geoenviron Eng, ASCE2006;132(10):1250–61.
[8] Reddy KR, Hettiarachchi H, Parakalla NS, Gangathulasi J, Bogner JE.Geotechnical properties of fresh municipal solid waste at Orchard HillsLandfill USA. Waste Management 2009;29(2):952–9.
[9] Reddy KR, Gangathulasi J, Parakalla NS, Hettiarachchi H, Bogner JE, Lagier T.Compressibility and shear strength of municipal solid waste under short-termleachate recirculation operations. Waste Manage Res 2009;27(6):578–87.
[10] Arulrajah A, Maghoolpilehrood F, Disfani MM, Horpibulsuk S. Spent coffeegrounds as non-structural embankment fill material: engineering andenvironmental considerations. J Clean Product 2014;72:181–6.
[11] Arulrajah A, Ali MMY, Disfani MM, Horpibulsuk S. Recycled glass blends inpavement base/subbase applications: laboratory and field evaluation. J MaterCiv Eng 2014;26(7):04014025.
[12] Grubb DG, Gallagher PM, Wartman J, Liu Y, Carnivale MC. Laboratoryevaluation of crushed glass-dredged material blends. J Geotech GeoenvironEng, ASCE 2006;132(5):562–76.
[13] Wartman J, Grubb DG, Nasim ASM. Select engineering characteristics ofcrushed glass. J Mater Civ Eng ASCE 2004;16(6):526–39.
[14] Kampala A, Horpibulsuk S. Engineering properties of calcium carbide residuestabilized silty clay. J Mater Civ Eng ASCE 2013;25(5):632–44.
[15] Horpibulsuk S, Phetchuay C, Chinkulkijniwat A. Soil stabilization by calciumcarbide residue and fly ash. J Mater Civ Eng ASCE 2012;24(2):184–93.
[16] Horpibulsuk S, Phetchuay C, Chinkulkijniwat A, Cholaphatsorn A. Strengthdevelopment in silty clay stabilized with calcium carbide residue and fly ash.Soils Found 2013;53(4):477–86.
[17] Kampala A, Horpibulsuk S, Chinkulkijniwat A, Shen SL. Engineering propertiesof recycled calcium carbide residue stabilized clay as fill and pavementmaterials. Constr Build Mater 2013;46:203–10.
[18] Kampala A, Horpibulsuk S, Prongmanee N, Chinkulkijniwat A. Influence ofwet-dry cycles on compressive strength of calcium carbide residue-fly ashstabilized clay. J Mater Civ Eng ASCE 2014;24(1):633–43.
[19] Arulrajah A, Ali MMY, Disfani MM, Piratheepan J, Bo MW. Geotechnicalperformance of recycled glass-waste rock blends in footpath bases. J Mater CivEng ASCE 2013;25(5):653–61.
[20] Taha R, Al-Harthy A, Al-Shamsi K, Al-Zubeidi M. Cement stabilization ofreclaimed asphalt pavement aggregate for road bases and subbases. J MaterCiv Eng ASCE 2002;14(3):239–45.
[21] Somna R, Jaturapitakkul C, Made AM. Effect of ground fly ash and groundbagasse ash on the durability of recycled aggregate concrete. Cement ConcreteComposite 2012;34:848–54.
[22] Somna R, Jaturapitakkul C, Chalee W, Rattanachu P. Effect of the water tobinder ratio and ground fly ash on properties of recycled aggregate concrete. JMater Civ Eng 2012;24(1):16–22.
[23] Vichan S, Rachan R, Horpibulsuk S. Strength and microstructure developmentin Bangkok clay stabilized with calcium carbide residue and biomass ash.Science Asia 2013;39:186–93.
[24] Ramasamy P, Periathamby A. Carbide sludge management in acetylene plantsby using vacuum filtration. Waste Manage Res 2002;24(6):536–40.
[25] Hologado MJ, Rives V, San Román S. Thermal decomposition of Ca(OH)2 fromacetylene manufacturing: a route to supports for methane oxidative couplingcatalysts. J Mater Sci Lett 1992;11(24):1708–10.
[26] Chindaprasirt P, Jaturapitakkul C, Sinsiri T. Effect of fly ash fineness onmicrostructure of blended cement paste. Constr Build Mater2007;21:1356–61.
[27] Sinsiri T, Chindaprasirt P, Jaturapitakkul C. Influence of fly ash fineness andshape on the porosity and permeability of blended cement pastes. Int J MinerMetall Mater 2010;17(6):683–90.
[28] Al-Khaja WA, Madany IM, Al-Sayed MH, Darwish AA. The mechanical anddrying shrinkage properties of cement mortars containing carbide lime waste.Resour Conserv Recycl 1992;6(3):179–90.
[29] Consoli NC, Prietto PDM, Carraro JAH. Behavior of compacted soil–fly ash–carbide lime mixtures. J Geotech Geoenviron Eng 2001;127(9):774–82.
[30] Horpibulsuk S, Rachan R, Raksachon Y. Role of fly ash on strength andmicrostructure development in blended cement stabilized silty clay. SoilsFound 2009;49(1):85–98.
[31] Horpibulsuk S, Katkan W, Sirilerdwattana W, Rachan R. Strength developmentin cement stabilized low plasticity and coarse grained soils : laboratory andfield study. Soils Found 2006;46(3):351–66.
[32] Horpibulsuk S, Rachan R, Chinkulkijniwat A, Raksachon Y, Suddeepong A.Analysis of strength development in cement-stabilized silty clay based onmicrostructural considerations. Constr Build Mater 2010;24:2011–21.
[33] Horpibulsuk S, Miura N, Nagaraj TS. Assessment of strength development incement-admixed high water content clays with Abrams’ law as a basis.Geotechnique 2003;53(4):439–44.
[34] Horpibulsuk S, Rachan R, Suddeepong A. Assessment of strength developmentin blended cement admixed Bangkok clay. Construct Build Mater2011;25(4):1521–31.
[35] Chinkulkijniwat A, Horpibulsuk S. Field strength development of repairedpavement using the recycling technique. Q J Eng Geol Hydrogeol2012;45(2):221–9.
