si,aj dl-U:*l otS^IL3 . ( % 0.5 ) jJlt]j y a;rU !+*ilj Jt^eyl i3rsl3 pt'i!l-9 O.''ill. 'lsJ'$ .... Recycled Aggregate Concrete will sufler of a higher drying shrinkage than that in the ... Chemical of Cement. Table of Cement. Table I. Mechanical of Cement. 1.2.
I
AL- Taqani,Vol . 25, No. 3 ,2012
INFLUENCE OF INTERNAL SULPHATE ATTACK ON SOME OF PROPERTIES FOR CONCRETE CONTAINING RECYCLBD * AGGREGATE ir..ll tlsJrll ,r& lSfsll ful-,JAJl oalJ. e * sJihJl ssLll o"Ll3Jl Ji'lil
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Jabbar Abbas Jabir. Abstract
:
This paper presents a comprehensive experimental study on the resistance of concrete made of fartial or full replacement of natural fine and coarse aggregates by recycled aggregates to internal sulphate attach as _the main problem in concrete production-in t.rq . The replacement and sulphate levels added were the main test 2'5oh) of variables in this stuoy. 'ftre sulptrate levels investigated were (0.5 , 1.0 , 2.0 and aggregate the while level, fine aggregate weighi in addition to that of control sulphate fine and coarse repla"-eLents ten"t". were (25, 50, 75,and 100%) of those natural strength were aggregates weights. The variations of linear expansion and compressive natural and both for days measured carefully and periodically up to the age of 180 recycled aggregate concretes . by recycled coarse Results indicated that , partial replacement of (75o ) Ievel impairing the without possible aggregate or recycled fine aggregate was practically (1.0 and 2'0o/o\ respectively at all concrete resistance to sulphate foialf SOI levels up to recycled aggregate on the (1'0%) the ages studied . Full."plu."*.nt level by one tyfe of Full replacement level by both SOr level was practically possible at all the ages iiudied-. all the must be done in"the lower SOr levels up to (0'5%) at types of recycled "ggr"gui.. by both recycled aggregates was practically ages studied. Fifty percent reRlac-em1nt level up to (l'0%) ' fissiUle for the uit ag". and SOr levels :r rali3r.,,.dl
fu^f*f 'at"'yAi*lJj e-.lr6i ei elr$ li! s'E Lfti"Jft fuf*Jill 6':Ei'z'Sl #Jr.ll gl\fey! elsil iP t:ls Ji !t'j+ tl-,,r+:oU slilJl sal^ll u,"Ullf A+,atil O'il| prS;$-9 PlJl *i ,s,JSr&]1 4+u; O! ' dl,rJt d fut-Jill ist'i'o ti^ sp i-Jr&ll c:lJini]l *i c* i-lL.a.Jl g)-Il i;.;3 Jlr.6'':l CJr+JI o/, (2.5 J 2.0 ' l'0 ' 0'5) d'itS i-3-)'r''ll 6)-Yl i+*.l O! ' i*..,j$ s{ e*Y,* pull ptsjl OiJ u. L*j sjts L^iJJ ' if+J"l % (100 t '15 ,50 , 25) sA L,J&l ftsil Jl+:r'l i). OjJJt st.ayt et,Jil lti;ill Lrl'i'r 4+lJLJl ''3lliill r+; o! ' o'''ill J Pul 1g0 J'.rJl ,.+ q;;Jl Js.ii3 air:! \i-11.r rj )Sl rlr-oJl
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Received onl7l2l20l0 ,Accepted on Ass. Profl Babil Technical Institute
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AL- Taqani,Vol .25, No.3 ,2012
ii,J ./.r rtr-t! pcUI .rS;$ 3i Jr-Jl a-iill dsil tl.$i-l Aifs.o! d 6r:E:ll o-11&i Lrlid ajLJAJl ctlrq ',,t;,::t 6l .,J..all (,r#Lll .lsJx ojj CFIJJI 9'6 L* glilJl 95l.ll (}ljjll 4+rLll ':'s"rtr-l tiJL a-6'll A!.rS3' CJIJI ,-P f/"2 J l) .rrJ r iilSirll 3i 1i.Uf dsil tlriL,l a;rs.ot i+iLl ;..*ill j',t+I ti ;c; (%100 ) Jl$-l i'*lr Pt':ll ets-'rll Jt$-,t ctts.)t+l .-llrll i.ils!3 (%l ) alE i3rsl3 pt'i!l-9 O.''ill y si,aj dl-U:*l otS^IL3 . ( % 0.5 ) jJlt]j a;rU !+*ilj Jt^eyl
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Introduction: waste concrete materials has steadily Recently, The availability of demolished aggregate due , there is.no locally available increased all over the world , and in,,rny.iii"t plants and the contaminations from the aggregate of the environmental limits which pr.u.r', and aggregates. From both, environmental recycled u.se.of the to the legislation use of these ";;;;."g. i.nporturt 1"^. .rsi"i-"-,s to ensure et-fective sustainability points of ,ilw , it is to achieve off'er a promising and reliable outlet concrete wastes, and the recycled aggregates of concrete of recycied aggregates in production this goal .ln practicJ,".u..Lrrzuf uppfi.ut"i*s of its (80%) over Denmark , which ,eJyttto noY ' being have been reported , especially in is *aste ' and crushed concrete in particular ' demolition UK ln . , waste demolition 'Ill .*"grir.O increasingly as a v^aluable resource important role in the mechanical physical properties of recycled ,gg."gui* qfay an particle shape of n"g"gr&u," boncrete(RAc) ' The Recycled l"g ,l*i the of water properries texture and this leads to more rura.e tL rougnli uni ung.iri, recycled aggregare as measured by slump' reportid that for the same workability Natural demand for wetting . It has been demand than that of a comparable increasing (5-15%) about there was 'n-'**"'i"rs of (RAc) is faster than that of (NAC)[2]' that.,'rr"nlp Aggregare con...t. tNiCl and accurately VivianW.Y.et.al.[3]proposedaninnouuti,.methodnu*.d''Real-TimeAssessmentof water absorption of recycled aggregate errors tn give Water Absorption, RAWA to *eu'u'"will turn in which cannot gi*L.ri"" ::::llt , because the rradirional method (25to60%)contaminated recyclei aggregate conta.ins of about the mix design. ffr.^rrrriu." of The amount of adhered a.*"r.l11;a .,..nlril?,i1"" original the on "on"tete' mortar depending than that in the case of high normal-strength concrete is lower recycred from resurting mortar area of a*EreBate' therefbre ' ,h: rh;^;;;.ir. with i;;""res ;;; :f :,Yrface the coarse srrength concrete the maximum aggregate size of in reduction the with adhered mortar i.,",eu,es uE"gttE"t is less than that of trr" ,"litjr. d.nrity or "ty"1to reason , 'that this For . aggregate [a] u a"niity reduction of about .' !i"Oi.t i"Oilllt-l aggregate natural recycled concrete the corresponding aggregate.using and the resulting (5%) is occurred'in the.ur. orrecycled of natural aggregate. and the natural those with than t,ost when compared "o*.rpoiiiii"aJnriti., recycled aggregates are higher i"oi.n, absorptiori jt .water "t is about'(5 to6)times and aggregate concrete n"ii,,i"' because'";t[;;;"u1 use and Frne 'u1iu"t aggregates in the.u...n, ln'ttt tu'" of recycled coarse that trran trro*e corielpororng mo.e fbr a tlme, than (12-15) about aggregate is lower abrasiot-, *. fb' nutu'al "ou"" The from aggregates..rp.;;;;.V ttut ttI u6'rurion ratio is raised
irJi"ut.o comparable.".yii"o.ourr. aggregat;:'l,rov
BRE about(23%)toabout(25-4[%)whentheSamecoarseagoreeateisrecycled[5]. u.t s;i;l;; Research Establishment lqsr ;;;;, BS Standards grade their British Now, according to re^cycled aggregate in'o tr-""t-grades Digest 433 :lggg t6l t7l classify is as tollows: of"use . The classiflcation 70
AL- Taqani,Vol . 25, No. 3 ,2012
l.Lower quality grade use recycled aggregate (ClassRCAl).This grade is originated by using the brickwork debris ,with replacement levels of about $Yo to100%) to achieve
lower grades of concrete (up to C20, or C35) . 2. Higher quality grade use recycled aggregate (Class RCA2). This grade is originated by using the concrete debris, with replacement levels of about (0% to 2A%)to achieve higher grades ofconcrete (up to grade C50) . 3. lntermediate quality grade use recycled aggregate (Class RCA3). This grade is achieved by using the concrete or brick debris with replacement levels of about (0-50%) Aggregates in Class RCA(2) will be suitable to substitute for Classes RCA(3) and RCA(l), and RCA(3) for RCA (l). An alternative way of classifying the recycled aggregates is the density . The materials with an average dryrelative density above of (2000or2100) kg/m3 may be classified as (crr"rshed concrete) . The materials with an average dryrelative density of less than (1500) kg/m'may be classified as (brick or ceramic) materials. The materials of dryrelative density of ( 1800) kg/m' may be classified in between of the previous two types . Studies related to the engineering properties of concrete incorporating recycled fine or coarse aggregates confirmed that, high quality concrete with recycled aggregate is a realizable goal with the depletion or scarcity of the natural quarries . Development in the aggregate production technologies , and the innovations in the recycling process have led to reliable and enhanced properties of recycled aggregates.Mario Bassan et.al.[8], indicated that, there was a negligible eflect occurred in the performance of structural grades of concrete if a blended natural aggregate with recycled one up to 30% was used. They concluded also, that , quality and homogeneity of recycled aggregate are necessary for a high quality concrete , and that using of (100%) of recycled coarse aggregate from precast production waste allows to make "High Strength Recycled Aggregate Concrete ,HSRAC". Lightweight recycled aggregate can be produced successfully by the fbrmulation a mixture of " Ethylene Vinyl Acetate ,EVA." with " Construction and Demolition Waste , CDW" to minimize the loss of strength and elastic modulus of the resulting concrete [9].
of (RAC) . He found led to a greater pore aggregate recycled by aggregate of natural that , higher replacement are of particular recycled aggregate raclius threshold[10]. Deformation and sorptivity of concern which will affect the long term durability of building structures [11]. In addition to that , (RAC) has a higher amount of interfacial transition zone (ITZ) as compared with that of (NAC) . This zone will produce a weaker zone in the concrete structure , which will be Jose studiecl the influence of replacement level on the porosity
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more vulnerable to the sulphate attack U2,l31.For the previous reasons, recycled aggregate is poorly performed and the studies are focused to improve this area by different methods such ur uring a method of the "Two Stage Mixing Approach , TSMA" . This a new mixing upprou& , which helps to form a thin layer of cement slurry on the original surf-ace of the up the recycled aggregate. This slurry permeates into the porous old cement mortar and fills of adoption The old cracks anJ voids to reduce the porosity of the recycled aggregate. (TSMA) can create an (ITZ) with greater surface area to which the cement mortar can attach , can be used to and thus an increased strength ottonstruction structure[14].Another method basis , studies this (RAC)'On improve the quality of (ITi) by using mineral admixture for (silica fume ,slag, or suggested thaf the use of certain amounts of pozzolanic materials such as ny astr )into the concrete mixture combined with a multi-stage mixing process enhanced the pioperties of (RAC)[15]. Studies based on the X- ray diffraction and scanning electron *i".or"opy analyses', found that the formation of gypsum and thaumasite as a result of of recycled sulphate attack was significantly contributed to the pronounced deterioration aggregate concrete I l6]-
7l
_
AL- Taqani,Vol . 25, No. 3
_.L
'2012
Recycled Aggregate Concrete will sufler of a higher drying shrinkage than that in the most Natural Aggregate Concrete . This is pri,narily due to the increased quantity of mortar within the concrete as a whole . There is an adhered mortar on the surfaces of recycled aggregate as well as to the additional mortar in the new recycled aggregate concrete[17]. Al- Khafbji J. A.[ 8], said that , studies on the effect of lnternal Sulphate Attack (l.S.A.) in the (NAC) in lraq indicated , that the allowable limits of sulphate in tlne aggregate may be raised to ( 1.0% ) without any destructive effects on the mechanical properties of the concrete . The same conclusion was achieved about the possibility of raising sulphate content in coarse aggregate . Also , studies in the case of concrete containing full or partial replacement by .."y.LO aggregates have been reported , and the results appear to be very promising ' More data are , however , required to enhance the confidence in its durable performance. It is when necessary to understand itre effect of recycled aggrcgate on the resistance of concrete exposedio sulphate attack, because, sulphate attack of (RAC) has not been fully established
ltel.
In this study, attempts to address some of the concerns related to the sulphate resistance aggregates ' of concrete made with partially or fully replacements by recycled fine and coarse and expansion linear the Tests were selected to investigate and compare the variations in ' attack is a long term compressive strength for the botn types of concretes . Internal sulphate ( days ' funciion , therefore , tests were done for along period up to the age of 180 ) Resea rch Sien
nce
:
to the following reasons: the increasing amounts -of disposal of from l.There are ,eriou, probleirs resulting were used for the security construction demolition wastes and cJncrete masses which The research is regarded a significant study due
a severe environmental problem in purposes . These aon.rat. productions have been created urgently our'country , and they *uti b" treated economically and increased especially fbr those areas in 2. The scarcity of natural aggregate of good quality has liom the adopted quarries' So' there the middle and south of our country , *hi"h lic tai away aggregates sources for promising alternative sources , such as the recycled
is a real demand cost resulting liom the transportation of which found in these areas themselves to limit the aggregate for large distances [9,20)' is done herein as a full 3. The replacement of natuial aggregate by recycled aggregate partial replacement ' ."ptu....nt instead of fine and coarse aggregate as well as in our country may be solved aggregatei the 4. 'fhe wide range p.otf"* of sulphate in dramatically by these alternative sources ' sources. 5. All the materials used here were from lraqi's
Experimental Work 1. Materials Used
of Kerbela tbctorv was used which
was and phvsical of Standards los5-84[21]'The chemical confirmed, with thelia;id;;"lrrtion in the Tables (1)A,B,C respectively : mechanical properties oithis cement is shown
bl;!#tll
rr,rnu,"
Resisting portland Cernent
11
I!
AL- Taqani,Vol . 25, No. 3 ,2012 Table
Chemical
Oxides
Percentages
CaO
64.6 21.6 4.2
sio2 AlzOr
of Cement
Requirements of I.O.S.
Meo
1.7
Fe203
5.1
SOs
2.1
