Recycled Chopped Rice Straw- Cement Bricks: Mechanical, Fire Resistance & Economical Assessment

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Australian Jurnal f Basic and Applied Sciences, C(): CC-CC, 011 ISSN 1991-8178 011, INSInet Publicatin Recycled Chpped Rice Straw- Cement Bricks: Mechanical, Fire Resistance & Ecnmical Assessment

1 Australian Jurnal f Basic and Applied Sciences, C(): CC-CC, 011 ISSN , INSInet Publicatin Recycled Chpped Rice Straw- Cement Bricks: Mechanical, Fire Resistance & Ecnmical Assessment Mstafa E. Allam, Gihan L. Garas, Hala G. El Kady Natinal Research Centre, Civil Engineering Department, Dkki, Cair, Egypt Abstract: In Egypt burning f rice straw releases large amunts f air pllutants causing serius envirnmental prblems. This paper addresses the recycling f chpped rice straw t prduce light weight cement bricks. Different tests were perfrmed t evaluate the rice straw brick (R-brick) with prpsed mix prprtins. Its weight is 5% lighter than the traditinal nes. Indirect fire expsure tests were perfrmed in accrdance t the ASTM A standards t cmpare fire expsure behavir f the R-bricks t market cement bricks. One and tw hurs expsure tests were perfrmed, with temperatures ranging between 00 and 800 C. Bth types f bricks did nt suffer any significant lss in cmpressive strength when expsed t 00 C fr 1hur. A lss f 70% in cmpressive strength f the rice-straw cement brick was reprted when expsed t 800 C fr 1 hur and 80% fr hurs fire expsure. The ecnmical investigatin shwed that the R-bricks under study cst 5% less than the standard cement brick. It was cncluded that the prpsed R-bricks prvides an ecnmical, light weight brick, with cmpeting thermal insulatin prperties, while maintaining adequate mechanical prperties, and fire resistance. Key wrds: Cmpsites, Chpped Rice Straw, Cement bricks, Recycling, Fire tests INTRODUCTION The Egyptian rice yield is ne f the highest in the wrld (9.1 tns per hectare in 001), a crp that leaves behind rughly 4.0 millin tns f straw annually. The methds fr dispsing f the straw and stubble residue remaining in the fields after harvest are either burning r baling. Althugh sme limited uses f rice straw such as animal feed r paper making are maintained, yet burning, the principal dispsal methd fr mst f the rice straw residue, is efficient, effective and cheap, even after being phased ut in the Egyptian law f Envirnment number [8]. As a result mst farmers tend t burn the straw in pen fields, bsting air pllutin and serius human health prblems due t the emissin f carbn mnxide. [] Since the 1950 s Egypt has adpted several lw-cst husing strategies, in an effrt t cmpensate fr grwing husing demands. At present, vast majrity f husing units are reinfrced cncrete structures with either bricks r cement blck infill, which are adpted materials frm ther climatic znes and cuntries with different types f natural resurces. One f the mst abandned materials in Egypt is cellulus nn-wd fibrus materials, such as rice straw. Instead f burning the straw, recycling it with a mixture f cement frms a sustainable lw cst building material, which als reduces atmspheric pllutin. In additin t these benefits, the resulting cmpsite rice -straw bricks culd act as a thermal insulatr that can be used in building fr the unpleasant Egyptian weather. The use f thermal insulatin helps reduce energy csts, while imprving indr temperatures. [] Akmal ( 006), cnducted a preliminary simple labratry study n preparing and examining rice strawcement bricks t be used as a filling blck in the traditinal skeletn building technique.[6]. Research Significance & Prblem Statement: Recycling rice straw t be used in building prcess is ne f the highly encuraged research areas that wuld yield great slutins t the majr envirnmental prblem resulting frm burning this residue. Rare infrmatin is available n the effect f adding such material t different cnstructin elements. This paper investigates the effect f adding rice straw t the cement bricks used in cnstructin. The bjective f this research is t evaluate the effect f adding chpped rice straw n the mechanical prperties and fire resistance f the cement bricks. An ptimizatin study was perfrmed between different mix Crrespnding Authr: Mstafa E. Allam, Natinal Research Centre, Civil Engineering Department, Dkki, Cair, Egypt mallam65@yah.cm 1

Aust. J. Basic & Appl. Sci., C(): CC-CC, 011 prprtins and the crrespnding cmpressive strength. Thermal prperties f the prpsed bricks are studied t prvide cnfidence in this new structural element.

2 Aust. J. Basic & Appl. Sci., C(): CC-CC, 011 prprtins and the crrespnding cmpressive strength. Thermal prperties f the prpsed bricks are studied t prvide cnfidence in this new structural element. Accrdingly, thermal cnductivity f the bricks will be measured and fire endurance evaluatin tests will be perfrmed. Finally, an ecnmical cmparisn between bth types f bricks will be undertaken and reprted fr the mass prductin use in the lcal market.. Design Mixs fr Rice Straw Bricks:.1 Mix Cnstituents: 1- Ordinary Prtland cement (OPC) frm lcal mark - Fine aggregate: siliceus sand with a maximum size f 5mm, well graded and free frm impurities. - Carse aggregate: free f impurities with nminal maximum f 10 mm and it was sieved t remve the particles smaller than mm. 4- Chpped straw fibers with length ranging between 0.5 t 1.5cm4 5- Natural fresh drinking water free f impurities.. Design Mix Prprtins: The cnstituents cnsidered in preparing and testing the mixes in this study are presented in Table (1). Table 1: Mix prprtins f Rice straw-cement bricks/1000bricks Type f Mix Fine Aggregate (m ) Carse Aggregate (m ) Chpped Rice Straw (Kg) Cement (Kg) M ix (A) M ix (B) M ix (C) Sampling and Mechanical Testing f Rice-straw Cement Bricks: 4.1 Intrductin Brick manufacturing is based n the principle f mixing and densificatin f a straw-cement brick mix t make a regular shaped, unifrm and high perfrmance masnry unit. The technique used is the same as the prductin f traditinal standard cement bricks using a mbile semi-mechanized egg-laying machine as shwn in Fig (1), and the prduct is a standard brick with dimensins 5*1*6 cm. Fig. 1: Semi-Mechanized egg-laying machine 4. Samples Casting & Curing: Carse and fine aggregates were batched by vlume using wden bxes with the desired vlume. Cement was added by weight using nly whle bags f 50 kg t ensure unifrm prprtins f mix. The chpped rice straw was added t the mixture accrding t the previusly mentined quantities. The dry mixes were batched utdrs in rtating pwer-driven reslving mixer f 100 liters capacity befre adding water.then the bricks were mlded and vibrated using 'egg-laying' mbile machines and then de-mlded immediately after cmpactin The samples were carried away n pallets t the curing place and they were regularly sprayed with water twice a day fr a perid f 7 days t gain sufficient strength. Visual inspectin revealed nn-cnsistency f mix C as it was weak and breakable by hand. Accrdingly; bricks f mix C were excluded.

Aust. J. Basic & Appl. Sci., C(): CC-CC, 011 4. Mechanical Testing: Fr each mix f the rice-straw cement bricks A and B, samples were tested in the labratry.

The dimensins f bricks fr each sample tested were measured precisely and an average f 6 * 1 * 5 cm dimensins were btained 4.

3 Aust. J. Basic & Appl. Sci., C(): CC-CC, Mechanical Testing: Fr each mix f the rice-straw cement bricks A and B, samples were tested in the labratry. Als samples f a standard cmmercial cement brick were tested t cmpare the cmpressin stress f each brick. The dimensins f bricks fr each sample tested were measured precisely and an average f 6 * 1 * 5 cm dimensins were btained 4..1 Cmpressin Test Apparatus: The Shumadsu 1000 KN universal tensin- cmpressin machine (Fig ) was used in testing the bricks fr cmpressin. The machine is equipped with a data analyzing utput unit fr utput data recrding. Fig. : The Shumadzu machine used fr testing the rice straw-cement bricks 4.. Testing Prcedure: Initially, the rice-straw bricks mixes under testing were prepared and cmpared with standard pure cement cmmercial bricks as shwn in Fig.. Fig. : Clr and texture f different samples. Bricks were placed flat n the platen f the testing machine. A 0.5 mm/sec rate f lading was applied n each specimen until failure. The cmpressin testing results fr all mixes are summarized in Table (). These results were cmpared t the values specified by the Egyptian Cde f Practice ECOP [7]

4 Aust. J. Basic & Appl. Sci., C(): CC-CC, 011 Table : Cmpressin Test Results MIX Specimen N. Max. lad (Tn) Max. Stress (Kg/Cm ) M IX A M IX B Cmmercial Sample The maximum cmpressin lads applied n the bricks shwed wide variance. The specimens f mix (B) cntaining 70 kg/1000 brick f chpped rice straw, shwed nn hmgeneity in its maximum cmpressive stress values 97.8, 7.5 and 49.0 kg/cm fr samples 1, and respectively. This can be due t the partial lss f bnd amng the mix cmpnents as a result f the excessive amunt f chpped straw existing in the mix. These scattered values didn t give cnfidence in this mix althugh within the specified values (70 kg/cm fr cmmercial cement bricks used as lad bearing walls and 5kg/cm fr bricks used as fillers in skeletn type buildings) stated by the Egyptian Cde f Practice ECOP [7]. The maximum cmpressive stress values fr specimens f mix (A) increased by decreasing the chpped rice straw cntent t 40 kg/ 1000 bricks using the same quantity f cement with almst the same amunt f fine aggregate. The maximum cmpressive stress values fr mix (A) were 114.4, and 11.6 kg/cm fr samples 1, and respectively shwing hmgeneity in its results. These values exceeded the values specified by the Egyptian Cde f Practice ECOP Cmpared t the values btained in Garas et al [] which reached stresses f 6.6kg/cm, these results are cnsidered relatively higher fr the same mix prprtins prduced by a different supplier. This culd be due t the lack f quality cntrl measures and inadequate curing time. Standard cmmercial samples btained frm the lcal market were cnsidered t be very hmgeneus with maximum cmpressive stress values f 177.9, 04. and kg/cm fr samples 1, and respectively. Accrdingly, rice straw cement bricks f mix A (40 Kg straw/1000 bricks) with the highest cmpressive strength f all mixes (115kg/cm in average) was chsen fr mass prductin purpses. Cnsequently, all further cmparative tests were cnducted between this brick and the standard cmmercial cement brick. 5. Characterizatin f Rice Straw Brick (R) Versus Cmmercial Cement Brick (C): 5.1. Chemical Analysis: A chemical analysis f the types f bricks under investigatin (Table ) was perfrmed t study the effect f its cnstituents n the mechanical behavir f the bricks. Table : Chemical Analysis f Rice Straw and Cement bricks percent by weight Cnstituents Rice Straw-brick Cement-Brick SiO Al tt FeO TiO NiO M n M g Ca SrO NaO BaO K O ZrO RbO Y O P O SO Cl LOI Calcium xide shwed t be the highest cmpnent in bth bricks (the majr cnstituent in the Prtland cement) fllwed by the silicn dixide which is the main cnstituent f sand, althugh slightly higher in the cement brick. This can be due t replacing a percentage f fine aggregates in rice straw bricks by chpped 4

5 Aust. J. Basic & Appl. Sci., C(): CC-CC, 011 rice straw particles. The Lss Of Ignitin (LOI) value was ne f the gverning items in the cnstituent percentage fr bth types f bricks. Its value fr the rice straw brick is 5% mre than in the cement brick which was previusly expected due t the presence f the chpped rice straw. This study prved that adding chpped rice straw as a natural material t the cement brick cnstituents des nt include any strange cmpnents (rather than the riginal nes f the cement brick) that might result in a negative effect n the prperties f the new rice straw brick. 5. Fire Resistance Test: 5..1 Instrumentatin and Test Setup: A custm built furnace f internal dimensins 60*85*165 cm (length *width * height respectively) was used t perfrm the fire testing. The maximum temperature that can be reached by the electric furnace is 100 C. The temperature time rate curve fr the furnace was adjusted t fllw the ASTM a [1] standard fire test curve (Fig 4). Detailed infrmatin abut instrumentatin can be fund in previus wrk by Elkady [4,5]. Fig. 4: Furnace Time-temperature curve, versus ASTM 119 fire test curve T insure unifrmity f temperature distributin, 4 K-type thermcuples were munted inside the furnace. Targeted temperature is prgrammed n the cntrl unit attached t the thermcuples. The ne hur expsure tests were cnducted at 6 temperature levels: 00,400, 500, 600, 700 and 800 C. Each test was cnducted n a set f three samples that was expsed t the assigned temperature fr ne full hur. The test was cnducted simultaneusly n bth types f bricks: cement and rice straw bricks. The secnd grup (hur expsure) was expsed t elevated temperatures up t 700 C. 5.. Fire Tests Results and Discussin: Figure 5 displays the reductin in cmpressive strength f the tested bricks due t ne hur f fire expsure. Bth types f bricks did nt suffer any significant lss f strength at 00 C. Starting frm 400 t 800 C, lss in strength f a maximum f 5% is nticed in cement bricks while the lss in the rice straw bricks strength graduated till reaching abut 70% f its riginal strength when expsed t 800 degrees fr ne hur. The tw hurs fire expsure test (Fig.6) revealed a maximum lss f abut 50% in the cement brick cmpressive strength cmpared t 80% lss in rice straw bricks under 700 C. 5. Ecnmical Study: Cst is a majr parameter in any industry. One f the main elements f cnstructin industry is brick manufacturing and its cst. Als utilizatin benefits f a brick add indirect savings fr cmparative purpses. Table 4 shws that the manufacturing cst f bth types f bricks indicates savings up t 5% f the ttal direct cst /1000bricks. This direct saving in csts is added t the envirnmental prfit f recycling rice straw which is traditinally burnt by farmers in pen fields, bsting air pllutin and serius human health prblems. Besides, rice straw material is knwn fr its high insulatin prperties which culd add anther indirect saving value by minimizing energy cnsumptin. 5

6 Aust. J. Basic & Appl. Sci., C(): CC-CC, 011 Fig. 5: One hur fire expsure test results fr R and C-bricks Fig. 6: Tw hurs fire expsure tests results fr R and C-bricks Table 4: Cmparisn between Cmmercial cement and Rice-straw brick Brick Type Average Cmpressive Stress Kg/cm Price /1000 Bricks L.E Cmmercial Standard Brick Rice straw-cement brick Cnclusin: This research presents an intensive evaluatin f recycling chpped rice straw t be used in the manufacture f cement bricks. The ptimized chsen mix f cnstituents 0.9 m fine aggregate, 0.9 m carse aggregate, 40 kg chpped rice straw and 400kg cement/1000 brick resulted in prducing a rice straw brick f density 5% less than the cmmercial cement brick. As fr cst saving, using rice straw brick resulted in 5% reductin in the prductin cst/1000brick. Chemical analysis was perfrmed n the cnstituents f the rice straw cement brick and the cmmercial cement brick, n strange materials were reprted. The fire expsure tests f chpped rice straw cement brick cmpared t lcal market cement bricks : The results indicated that the lss in the cmpressive strength f bth types f bricks under study increased by the increase f temperature, and the perid f fire expsure. In rder t use the rice straw brick in lad bearing walls, the fire temperature shuld nt exceed 400 C t reach stress up t t70kg/cm, while in case f using it as filler in skeletn type buildings, it can maintain temperatures even mre than 800 C fr 1 hur fire expsure t cmply with the Egyptian Cdes f practice. The rice straw brick is unable t be used as a lad bearing wall if expsed t hurs fire expsure due t the dramatic lss in its cmpressive strength. Reductin in strength due t fire expsure up t 00 C fr 1 hur did nt have significant effect n the cmpressive strength f bth types f bricks. It was cncluded that the prpsed rice straw bricks prvides an ecnmical, light weight brick, with cmpeting thermal insulatin prperties, while maintaining adequate mechanical prperties, and fire resistance. 6

7 Aust. J. Basic & Appl. Sci., C(): CC-CC, 011 REFERENCES ASTM E119-00a, standard test methds fr fire tests f building cnstructin and materials, ASTM internatinal, west Cnshhcken, Penn. Di: /E Mansur, A., J. Srebric and B.J. Burley, 007. Develpment f Straw-cement Cmpsite Sustainable Building Material fr Lw-cst Husing in Egypt, J. Appl. Sci. Res., (11): Garas, G., H. El Kady and A. El Alfy, 010. Develping A New Cmbined Structural Rfing System Of Dmes And Vaults Supprted By Cementitius Straw Bricks, ARPN Jurnal f Engineering and Applied Sciences, under publicatin. Elkady, H., 010. Effect f High Temperature n CFRP Retrffitted Clumns, Prtected with Different Catings, Structural Fire Engineering Jurnal, 1(): Elkady, H. and A. Hassan, 010. Prtectin f reinfrced cncrete beams retrfitted by carbn fibrereinfrced plymer cmpsites against elevated temperatures, Canadian jurnal f civil engineering, pp: Tamer, R., 006. Recycling f rice straw in the manufacture f building materials: A Study f Manufacturing Building Bricks. Mdern University - Department f Architecture(in Arabic). The Egyptian Cde f Practice ECOP, Ministry f husing and urban cmmunities, 005. The Egyptian law f Envirnment number

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