concrete

Journal of Hazardous Materials 264 (2014) 403 410

Contents lists available at ScienceDirect

Journal of Hazardous Materials

jou rn al hom epage: www.elsev ier .com

Environ nacontain ndconcre

Savas Erda Department ob Correspondin

h i g h l

Use of recycled aggregates (RA) from either waste precast concrete or recycled asphalt pavement (RAP) in concrete. Effects of RA on the fresh, mechanical and environmental properties of concrete. From the perspective of the mechanical properties, RAP can be used in non-structural applications. The environmental behaviour of the recycled aggregate concrete is similar to that of the natural aggregate concrete.

a r t i c l

Article history:Received 23 AReceived in reAccepted 16 NAvailable onlin

Keywords:Sustainable coWaste aggregaMechanical anLeaching beha

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a b s t r a c t

The overall objective of this research project was to investigate the feasibility of incorporating 100%recycled aggregates, either waste precast concrete or waste asphalt planning, as replacements for virginaggregates in structural concrete and to determine the mechanical and environmental performance ofconcrete containing these aggregates. Four different types of concrete mixtures were designed with thesame total water cement ratio (w/c = 0.74) either by using natural aggregate as reference or by totallyreplacing the natural aggregate with recycled material. Ground granulated blast furnace slag (GGBS) wasused as a mineral addition (35%) in all mixtures. The test results showed that it is possible to obtainsatisfactory performance for strength characteristics of concrete containing recycled aggregates, if theseaggregates are sourced from old precast concrete. However, from the perspective of the mechanicalproperties, the test results indicated that concrete with RAP aggregate cannot be used for structural appli-cations. In terms of leaching, the results also showed that the environmental behaviour of the recycledaggregate concrete is similar to that of the natural aggregate concrete.

2013 Elsevier B.V. All rights reserved.

ction

an exaggeration to say that concrete produced withment is so far the most popular construction materialorld due to its relatively inexpensive cost and versa-ete is adaptable to a wide variety of civil engineeringm high-rise buildings to road pavements, from bridgespply schemes, from retaining walls to railway sleepers.he role of concrete in promoting societys developmentt doubt, continue to play a crucial role in the foreseeableever, it should be pointed out that the concrete indus-es huge amounts of natural aggregates which cause

ding author. Tel.: +44 115 823 2424.ress: [email protected] (M.A. Blankson).

destruction of the environment. Therefore, there is an urgent needto nd and supply suitable substitutes for natural aggregates [1].

According to Sani et al. [2], a well-known example of alterna-tive supply of aggregate is the use of construction and demolition(C&D) waste to manufacture recycled aggregates. Waste comingfrom construction and demolition (C&D) represents one of Euro-pean Unions (EUs) largest waste streams. The gures obtainedfrom Waste Stream Programme, European Commission [3] revealthat waste materials arising from C&D activities amounts to180 million tonnes/year in the EU, which is equivalent to 480 kg perperson/year and 72% (130 million tonnes/year) that is land-lled. Ifthis volume of waste can be used constructively, it would removean enormous pressure on the environment.

Recycled aggregates have been used in non-structural concreteapplications or used as sub-base for roads [46]. Their uses instructural concrete, on the other hand, are limited and only a fewcases have been reported on the use of recycled aggregates in

see front matter 2013 Elsevier B.V. All rights reserved.rg/10.1016/j.jhazmat.2013.11.040mental performance and mechanical aing recycled asphalt pavement (RAP) ate as aggregate

ema, Marva Angela Blanksonb,

f Civil Engineering, University of Istanbul, Avcilar Campus, IstanbulTurkeyg author, School of Civil Engineering, The University of Nottingham, NottinghamUK

i g h t s/ locate / jhazmat

lysis of concrete waste precast

404 S. Erdem, M.A. Blankson / Journal of Hazardous Materials 264 (2014) 403 410

structural concrete. Desmyster and Vyncke [7] provided severalpractical examples on the use of recycled aggregates in structuralconcrete applications. Examples that were reported are related toengineering works on a viaduct and a marine in the Netherlandsin 1988, anused recycl

Several on the plascretes. In onstrength of It was foundmade withof concretethat the recrete than istrength ofdepended ogate/cemenconcrete wof natural afound that tlevel increareplacemenattributed tof the concever, with tthe developimately parhowever, thconducted no consensfor.

Corinaldwith 30% Rclass. This studied theproduced wEach type ocoarsely anconcrete wment from that the strreplaced wwas the ndner naturaaggregate. mental inveconcrete wsources andon the otheand modulument (RAP)or ne RAP

With redeterioratioleaching being naturaldemonstratCl goes up dof recycled ions. Reseanatural aggat up to 30in the oxidat higher RAl2O3 and t

concrete increased. The changes in the percentages of the oxideswere ascribed to the increase in the cement content of the concretesamples that were designed to attain 20 MPa in compressivestrength. In comparing the proportions of some of the elements in

id cooducpencret

oversibilite orn strnmen

teria

oper

tlandas udy. N139 adetionsed hhireal sizggreg

1. T theed ocled

aggrt Cot from

excao 10t wasoundhe mlace.

oduc

rderof co

of fo miValleer hast convestiand tste p

dryabsoring we samwereifferehichatess wed to an ofce building in the UK in 1999- all of whiched aggregates.researchers assessed the effect of recycled aggregatetic and hardened properties of recycled aggregate con-e assessment, Tabsh et al. [8] studied the effect of the

recycled concrete aggregate on the strength of concrete. that the compressive and tensile strengths of concretes

recycled concrete aggregates were lower than thoses made with natural aggregates. The ndings showedduction in strength was higher in low strength con-n medium strength concrete. It was concluded that the

the concrete made with recycled concrete aggregatesn the strength of the aggregate as well as the aggre-t ratio. When Kwan et al. [9] studied the properties ofith various replacement levels (0, 15, 30, 60 and 80%)ggregate for recycled concrete aggregate, it was alsohe strength of the concrete reduced as the replacementsed but the reduction was appreciably greater when thet level exceeded 30%. The reduction in strength waso the cracks that were developed in the aged mortarrete aggregate during the comminution process. How-he exception of two points of deviation, the trajectory ofment of strength in each type of concrete was approx-allel to each other up to 56 days. It should be statedat although considerable amount of research work is

on concrete with recycled concrete aggregates, there isus on which type of work this concrete is most suitable

esi [10], however, reported that concrete can be madeCA for structural concrete that is in the low strengthconclusion was arrived at after the latter researcher

mechanical properties of ordinary concrete that wasith two types of gravelone coarse and the other ne.f natural aggregate was alternately replaced with 30%d 30% nely crushed RCA aggregate respectively, inith water/cement ratio increasing in a small incre-0.40 to 0.60. The ndings concurred with some reportsength of concrete decreased when natural aggregate isith recycled concrete aggregate, but equally importanting that the reduction in strength was greater when thel aggregate was replaced with ne recycled concreteIn parallel, Kou and Poon [11] completed an experi-stigation on the long-term mechanical performance ofith recycled aggregates obtained from three different

the outcome supported this view. Huang et al. [12],r hand, reported that both the compressive strengths of elasticity of concrete with recycled asphalt pave-

decreased systematically, regardless of whether coarseused.gard to chemical attack, one of the reasons for then of concrete with is leaching. Sani et al. [2] surveyedhaviour of concrete manufactured by totally replac-

aggregate with recycled aggregate. The test resultse that the leachability of unreactive ions such as Na, K,ue to the presence of recycled aggregates, but the useaggregates resulted in a lower net leaching of calciumrchers [13] also conducted test on concrete that hadregate replaced with up to 100% RCA. It was found that% RCA replacement, there was no noticeable changees of Si, Ca and Al in the recipient concrete. However,CA replacements, the SiO2 decreased slightly and thehe CaO increased marginally as the RCA content in the

the solwas prthe prothe con

Thethe feaconcregates ienvirogates.

2. Ma

2.1. Pr

Por[14] wtal stuEN 13tures mconvengates uDerbysnomineach ain Fig.lar andconsistof recycoarseof Trenasphaltrenchwas alsasphallar. Grfrom ttial repGroup

2.2. Pr

In oerties a totalrst tw(Trent on oth(precaas to inerties the wasurfacewater of mixwas thmixes only dgate, waggregbatchencrete with that of similar elements in the eluate thated from each type of concrete, it was concluded thatsity for leaching was related to the chemical content ofe in the solid form.all objective of this research project was to investigatety of incorporating 100% recycled aggregates, either old

old asphalt planing, as replacements for virgin aggre-uctural concrete and, to determine the mechanical andtal performance of concrete containing these aggre-

ls and methodology

ties of materials used in concrete production

Cement Cem IIA-LL 42.5 conforming to BS EN 197-1sed to produce all concrete mixes in this experimen-atural sand complying with the requirements of BS

[15] constituted the ne aggregate for concrete mix- with recycled aggregate as well as concrete made withal aggregate. The two types of natural coarse aggre-erein were crushed limestone from Longcliffe Quarries,

; and gravel from Trent Valley, Nottinghamshire. Thee of both types of natural aggregates was 10 mm andate was blended to closely t the grading curve shownhe shape of limestone particles was primarily angu-

texture was rough, while the Trent Valley aggregatef smooth and rounded particles. Similarly, two sources

aggregates were used to totally replace the naturalegates; one coming from the precast concrete wastencrete Company and the other coming from recycled

Yorkshire Water Company that was carrying out thevations. The nominal size of the recycled aggregates

mm. The shape of the aggregate particles from recycled irregular, whereas that of precast concrete was angu-

granulated blast furnace slag, which is a by-productaking of iron, was used in concrete mixes as a par-

ment of Portland cement. It was obtained from Appleby

tion of concrete mixtures

to compare the environmental and mechanical prop-nventional and recycled aggregate concrete mixtures,our batches of concrete mixtures were prepared. Thex batches were produced with 100% natural aggregatesy and crushed limestone). The other two mix batches,nd, were each designed with 100% recycled aggregatescrete waste in one and recycled asphalt in the other) sogate the effects of recycled aggregates on concrete prop-he utilization of C&D wastes in concrete. The RAP andrecast concrete aggregates were used in the saturated

condition and extra water was used to compensate forption in the natural aggregates. Therefore, the quantityater used ensured that the water/cement ratio (0.74)e in all batches and other components in the concrete

determined in the proportions as shown in Table 1. Thence among the concrete batches was the type of aggre-

gives an opportunity to observe the inuence of the characteristics on the performance of the concrete. Allre composed of the same proportion of GGBS (35%) as a

S. Erdem, M.A. Blankson / Journal of Hazardous Materials 264 (2014) 403 410 405

rve of

cement repin the mixtu

After the100 mm cuand then coentrapped afor 24 h anduated in a rand three c

2.3. Tests a

Concreteevaluate thproceduresstrength wand 28 dayThe exura100 100 the relevanultrasonic pout using 10day accordibehaviour odures descralready beefully crushe

Table 1Concrete mix p

Materials

Cement Coarse aggreFine aggregaWater GGBS Water/ceme

he Sftwats o

ults

esh p

raphsultIn gebilityAs ca0 mmFig. 1. A graphical presentation of the grading cu

lacement material. No chemical admixtures were usedres.

mixing procedure, the fresh concrete was placed intobes and into 100 100 500 mm prisms in two layersnsolidated by using a vibration table to release possibleir. Thereafter, the specimens were left in their moulds

nally cured at 20 2C in a water tank that was sit-oom with 65% relative humidity. Four concrete cubesoncrete prisms were prepared for every batch.

nd analysis performed

cubes with 100 mm nominal size were used toe compressive strength of concrete according to the

teststyser Soelemen

3. Res

3.1. Fr

A gEach recrete. workagates. was 15 described in BS EN 12390-3 [16]. The compressiveas performed on the concrete specimens at 1, 5, 7s with reference to the abovementioned test method.l test with two-point loading was conducted on the

500 mm beam specimens at 28 days according tot standard, BS EN 12390-5 [17]. The measurement forulse velocity and dynamic elastic modulus was carried0 100 500 mm beams and performed almost everyng to BS EN 12504-4 [18]. In this project, the leachingf concrete specimens was observed using the proce-ibed in BS EN 12457-2 [19]. Cube specimens which hadn used for 28 days compressive strength testing, wasd and tested using one of the new European leaching

roperties.

kg/m3

175.5gate 980te 900

20094.5

nt ratio 0.74

est slump concrete wasphalt aggally, aggregspecic sursize and th the aggregates used.

hake Test (Fig. 2). Subsequently, the ELIT pH/Ion Anal-re was used to determine the concentration of certainf each sample (Fig. 3).

and discussions

roperties

ical representation of slump height is shown in Fig. 4. is the average of two slump measurements on the con-neral, the test results indicated a decreasing trend of

when the recycled aggregates replaced natural aggre-n be seen from the gure, the highest slump measured

in concrete with limestone aggregates, while the low-

measured was 50 mm in concrete containing precastaste. The slump values for Trent Valley and recycledregate samples were 130 and 90 mm, respectively. Usu-ates with smooth and rounded particles have lowerface than those with rough and angular particles of equalerefore more water used in the wetting of the surface.

Fig. 2. Agitation device for shake (leaching) test.


Fig. 3. Chemical analysis of sub-samples with ion-selective electrode technique.

As less mixing water will made available in concrete with roughand angular coarse particles, the slump of this type of concretewill be less smooth andconcrete habe the resulthat was readvantageo

It was oshowed accand compaworkabilitystituents arworkabilitygates. Frommixes that workable ththe waste pattributed twater absovisual examwere angulafeatures wowater and hcrete. Explaaggregate ilar coarse pembedded gate particlseparated f

Table 2Compressive strength test results. .

Compressive strength (MPa)

Mix ID 1 day 5 days 7 days 28 days

Trent Valley concrete 2.2 9.5 12 21.4Limestone concrete 3.8 15.5 18.8 32.2Waste precast concrete 4.1 19.8 22.0 36.6Recycled asphalt pavement 1.6 8.9 10.0 14

Table 3Saturated surface-dry density of the concrete mixes.

Saturated surface-dry density (kg/m3)

Mix ID 1 day 5 days 7 days 28 days

Trent Valley concrete 2305 2325 2335 2335Limestone concrete 2305 2340 2345 2350Waste precast concrete 2350 2350 2355 2365Recycled asphalt pavement 2260 2265 2280 2310

the absorption capacity of the RAP aggregate. Although this expla- appears plausible, it is suggested that further testing ofgregate ption.

mpr

testixes

dayy of o 235avel), as creapme

hyd 5 bee stte mly bad preaste rengonge

[20]gregthan that of a similar proportioned concrete made with rounded aggregate particles. However, the limestoned a higher slump that the gravel counterpart which mayt of a slightly higher percentage of limestone aggregatetained on the 4.5 mm sievea feature that would workusly to increase the slump.bserved that the recycled concrete aggregate sampleseptable workability performance in terms of placementction. The slump of the concrete is indicative of the. Although this correlation is more useful when the con-e the same, it will be used here for the comparison of

of cementitious materials with different types of aggre- the experiment, the results show that the concretewere manufactured with recycled aggregates were lessan those made with natural aggregates. In the case ofrecast concrete, the reduction in workability may beo a combination of the low specic density and highrption of this type of recycled aggregate. Additionally,ination showed that the pieces of precast aggregater and contained signicant amount of old mortar. Theseuld have also helped to reduce the effective mixingence reduced the workability of the waste precast con-nation of the slump in the concrete made with RAPs more difcult. The RAP used was composed of angu-articles and sand; both of which were fully or partiallyin bitumen. As mixing took place, more of the aggre-es and sand may have become exposed as the bitumenrom the granular particles, resulting in an increase in

nationRAP agaggregabsorp

3.2. Co

Thecrete mThe 28densit2250 t(the gr7 dayscrete indevelosilicate

Fig.pressivconcrethe oncrushethat wsion stof a strmortarcast agFig. 4. A graphical representation of the slump results. Fig. 5. A grapates is done to determine if the volume of unblockedores in RAP can contribute to noticeable level of water

essive strength and density

results of compressive strength and density of the con- are summarised in Table 2 and Table 3, respectively.s compressive strength and the saturated surface-drythe concrete samples varied from 14 to 36.6 MPa and0 kg/m3, respectively. With the exception of a few cases

concrete at 28 days and the waste precast concrete athydration progressed, the density of each type of con-sed and the corresponding strength also increased. Thisnt is attributed mainly to the production of the calciumrates.low gives a graphical representation of variation of com-rength with age. The target strength for the recycledixes was 35 MPa. From these results, it is shown thattch that met the target strength is the batch containingcast waste concrete (36.6 MPa at 28 days). Fig. 5 showsprecast concrete consistently had the highest compres-th both at early and later ages. This may be the resultr physical bond between the aggregate and the cement. It also should be pointed out that limestone and pre-ate mixes showed similarity in performance, probablyhical representation of the compressive strength results with age.


Fig. 6. Scanning electron image of the concrete mix with RAP.

because the origin of the precast concretes aggregate is from thelimestone.

The bathand, had there was matrix/aggrably becausnew mortaalong as sho

The varisented in Fiobtained dulow, then a strength miproportion shows that has gained days value few days, Tproportion imens. Basethe concretstrength bo

Fig. 7. Scannin

Fig. 8.

3.3. Flexura

The test studied are

te sp concnd tm Fig

streggreconvpecim

streate eith Tossibape arengs thon beate wal strough

andte w

10 (d Troweinaeench with recycled asphalt aggregate, on the otherthe lowest strength; probably reecting the fact thatweak bonding between the asphalt and the concreteegate [12]. However, a stronger reason for this is prob-e the bitumen lm between the old aggregate and ther provides a line of weakness for failure to take placewn in scanning electron micro-graphs (Figs. 6 and 7).

ation in compressive strength gained with time is pre-g. 8. This gure shows the proportion of nal strengthring the early life of concrete, but if the nal strength ismaterial that quickly gains a high proportion of its nalght still be weaker than a material that gains a smallerof a greater nal strength in the same time. Fig. 8 alsothe compressive strength of recycled asphalt concretethe majority of its long-term strength after only a fewas compared to the other concrete specimens. After arent Valley aggregate concrete has gained the lowestof its long-term strength among all the concrete spec-d on these results, the most signicant point is thate produced with recycled concrete aggregate has gainedth rapidly and substantially.

concrefor thestone a

Frotensilecrete ausing crete stensileaggregcrete w

A pthe shural stsuch agate caaggregmaterilar or rbinderconcre

Fig.RAP anures shpredomis betwg electron image of the crack path in the concrete mix with RAP.

the Trent Vcracking anaggregate iconcrete.

3.4. Ultraso

The testmeasured uDIT), for th

From thtransit time112 to 123.the elastic gate is clearaggregate. crete mixtu The variation in the compressive strength gained with time.

l tensile strength

results of exural tensile strength of the concrete mixes presented in Fig. 9 below. The exural strengths of theecimens at 28 days were 3.02, 4.16, 4.74 and 4.80 MParete with RAP aggregate, the gravel concrete, the lime-he waste precast concrete, respectively.. 9 below, it can be seen that while the highest exuralngth is in concrete made with precast waste con-gate and its strength is similar to the concretes madeentional aggregate, the other recycled aggregate con-en that included recycled asphalt, showed the lowest

ngth performance. The concrete with limestone naturalxhibited a slightly higher performance than did con-rent Valley natural aggregate.le explanation for this behaviour is the inuence ofnd the surface texture of the aggregate on the ex-

th of concrete. Angular or crushed aggregate particlesse in the limestone or precast waste concrete aggre-

dovetailed in the mortar. This means that this type ofill have a greater adhesion or bond leading to a higherength. Likewise, the larger surface area of a more angu-er aggregate particle offers larger contact area for the

, thus a higher exural strength can be expected fromith these aggregates.a) and (b) shows the broken faces of the concrete withent Valley concrete after exural tensile test. The g-d that the concrete produced with RAP tended to failntly through the interfacial transition zone (ITZ) that

the surfaces of the RAP and the mortar. In contrast,alley concrete showed signs of failure emanating fromd fragmentation of the aggregates, indicating that thetself is the most vulnerable feature of the Trent Valleynic pulse measurements

results of the modulus of elasticity and transit time, assing the non-destructive ultrasonic test method (PUN-e concrete specimens are presented in Fig. 11 below.e experimental results, the 28days elastic modulus and

of the specimens vary from 39.1 to 47.6 GPa and from5 s, respectively. In addition, the result indicates thatmodulus of the concrete produced with natural aggre-ly higher than that of the concrete containing recycledFrom the Fig. 11 above, the transit time of the all con-res at early ages decreased dramatically but maintained


Fig. 10. Failedwith gravel ag

a relativelydays.

Fig. 12 pared withof elasticitycompressivis probablythan by mstrength (mresult in coa single rematerials exconsistentlyvalue. This originally sor 75 MPa Fig. 9. A graphical representation of the exural

samples after the exural test (a) concrete with RAP and (b) concretegregate.

stable position with small uctuations from 7 until 28

shows that the variation of elastic modulus com- compressive strength. It appears the static modulus

does not increase proportionally with the increase ine strength. From this it may be deduced that stiffness

more inuenced by aggregateaggregate connectionortaraggregate bond, so continued development ofostly a result of increasing bond strength) does notnsiderable increase in stiffness. Fig. 12 seems to showlationship between stiffness and strength for all thecept for the precast concrete aggregate mixture which

had a lower modulus for any compressive strengthcan be explained as the precast concrete aggregate wasourced from very high strength concrete, such as 70strength and thus, it includes a greater proportion of

Fig. 11.

high strengmixtures.

3.5. Leachin

The testsurements,and Table 5

Fig. 12. Ultras tensile results.Ultrasonic dynamic modulus and transit time vs. concrete age.

th cement (or stiffer aggregate) content than the other

g measurements

results of pH, electrical conductivity and leaching mea- as determined using the shake test, are given in Table 4, respectively. The analysis included conductivity, pH

onic modulus of elasticity and compressive strength relationship.


Table 4Electrical conductivity and pH results.

Mix ID Conductivity (s) pH Temperature (C)

Trent ValleyLimestone cWaste precaRecycled asp

Table 5Leaching analy

Solution

ConcentratioChloride Cadmium Nitrate AmmoniumSodium

and the conand ammon

As is cleexperimentNH4 and Nhigher propValley gravRAP concreilar results that the conto the total shown in thwith Trent Vand pH, altspecimens.

As can band ammonduced withThis is likelrecycled agthe old moaggregate cto leach ouasphalt aggcrete whichthe recycled

Based onleaching qualthough sotherefore thsoluble thaing performsimilar to th

4. Conclud

In the listudy, the f

It was fouany difcureplacingreduces th

recycled aggregates requires more water or superplasticizer [21]to achieve the same workability as conventional concrete.

Concrete produced with 100% recycled coarse precast con- aggregates may have a higher cube compressive strength

con = 0.7al st

ructuegateast oresualt agive snexpese tructanicturaresulegateral sing aary ancrerms ehavral ag

nces

. Tu, Yent Cani, Goncre182ladernagemParanaprop2.. Poon

bric585. Pooncks pr07) 16esmyaggregRecy. Tabstren311 concrete 5.19 12.36 21.6oncrete 6.01 12.43 21.6st concrete 5.90 12.42 21.6halt pavement 4.87 12.37 21.6

sis results.

Trent Valley Limestone Waste precastconcrete

Recycled asphaltpavement

ns (mg/L)0.0255 0.0265 0.0159 0.06340.00045 0.00102 0.00051 0.000613.4845 3.8336 3.8642 4.1677

2.0220 2.1488 3.2844 1.884082.4195 81.3634 91.1912 80.7211

centrations of sodium, lead, cadmium, chloride, nitrateium in clean water.ar from the tables, all the concrete specimens in thisal work leached the same components (Pb, Cd, Cl, NO3,a). The leached components seems to be in slightlyortions from the precast waste aggregate and Trentel compared to those leached from the limestone andte samples. However, each assessment gives very sim-for all specimens. This may be attributable to the facttribution of the migration of these ions from aggregateleaching process is usually minimal. Similar ndings aree results of the electrical conductivity. The concrete mixalley aggregate has the highest electrical conductivity

hough the pH value is very similar for all the concrete

e seen from the tables, the acidic compounds, i.e. nitrateium, leached in large quantities from the concrete pro-

recycled aggregates, mainly precast waste aggregate.y due to the fact that the concrete manufactured withgregate had extra cement, which was inherited fromrtar. Thus, acid-neutralizing capacity of the recycledoncrete is greater. Certain metals (chloride, nitrate) tendt in high concentrations from concrete with recycledregates. This may be attributed to the high pH in the con-

led to the increased solubility of these organics from

cretethan(w/cnormin staggrprec

The asphpressan uon thfor smechstruc

The aggrexuneerprimin co

In tetal bnatu

Refere

[1] T.YCem

[2] D. Sof c177

[3] C. PMa

[4] S. on 11

[5] C.Sclay578

[6] C.Sblo(20

[7] J. Das ETN

[8] S.Won 116 asphalt concrete. the results, one of the interesting points is that theantity of sodium is high in all the concrete mixtures,dium is a minor component of Portland cement andis may be a constituent of the GGBS or it may be moren the other ions. It is clear from the results; the leach-ance of concrete with primary aggregates is generallyat of recycled aggregate concrete.

ing remarks

ght of the ndings obtained from this experimentalollowing conclusions can be drawn:

nd that recycled aggregate concrete mixes did not poselties in terms of casting or placement. However, totally

the natural aggregate with a recycled one signicantlye workability of concrete. Consequently, concrete with

[9] W.H. Kwrecycled Build. Ma

[10] V. Corinrecycled-161616

[11] S.C. Kou, Crecycled 60 (2008

[12] B. Huangcrete con200820

[13] M.C. Limacterizati201208

[14] BS EN 19Common

[15] BS EN 13[16] BS EN 123

imens, Br[17] BS EN 12

mens, Bri[18] BS EN 12

British Stventional concrete, with the same total w/c ratio4) and cement quantity (175.5 kg/m3). Furthermore, arength concrete can be produced with potential usesral applications. However, it must be stressed that the

should be sourced from high-strength concrete, i.e.r prestressed concrete, to achieve this aim.lts also indicated that concrete made with recycledgregates exhibited a systematic reduction in both com-trength and modulus of elasticity. However, it providedected increase in exural strength of concrete. Basedresults, the use of RAP aggregate is not recommendedural elements. However, from the perspective of theal properties, it is shown that RAP can be used in non-l applications.ts also showed that the presence of recycled concrete

in concrete may lead to an enhancement of concretetrength which might be benecial in some civil engi-pplications. It was observed that totally replacing theggregate with the recycled one causes a clear reductionte elastic modulus.of leaching, the results also showed the environmen-iour of the recycled aggregate concrete is similar to thegregate concrete.

.Y. Chen, C.L. Huang, Properties of HPC with recycled aggregates,oncrete Res. 36 (2006) 943950.. Moriconi, G. Fava, V. Corinaldesi, Leaching and mechanical behaviourte manufactured with recycled aggregates, Waste Manage. 25 (2005).er, Towards Sustainable Plastic Construction and Demolition Wasteent in Europe, European Workshop, Brussels, 2006.vithana, A. Mohajerani, Effects of recycled concrete aggregateserties of asphalt concrete, Resour. Conserv. Recy. 48 (2006)

, D. Chan, Feasible use of recycled concrete aggregates and crushedks as unbound road-subbase, Constr. Build. Mater. 20 (2006)., D. Chan, Effects of contaminants on the properties of concrete pavingepared with recycled concrete aggregates, Constr. Build. Mater. 214175.ster, J. Vyncke, net/RILEM Workshop, on use of Recycled materialsates in construction industry, (posters), in: Proceedings of the 1st, ETNRecy, net, Paris, 2000.sh, A.S. Abdelfatah, Inuence of recycled concrete aggregatesgth properties of concrete, Constr. Build. Mater. 23 (2009)67.an, M. Ramli, K.J. Kam, M.Z. Sulieman, Inuence of the amount ofcoarse aggregate in concrete design and durability properties, Constr.ter. 26 (2012) 565573.aldesi, Mechanical and elastic behaviour of concrete made ofconcrete coarse aggregates, Constr. Build. Mater. 24 (2010)20..S. Poon, Mechanical properties of 5-year-old concrete prepared with

aggregates obtained from three different sources, Mag. Concrete. Res.) 5764., X. Shu, G. Li, Laboratory investigation of Portland cement con-taining recycled asphalt pavements, Cement Concrete Res. 35 (2005)13.bachiya, E. Marracchino, A. Koulouris, Chemical-mineralogical char-on of coarse recycled concrete aggregate, Waste Manage. 27 (2007).7-1, Cement Composition, Specication and Conformity Criteria for

Cements, British Standards Institution, 2000.139, Aggregates for Mortar, British Standards Institution, 2002.90-3, Testing Hardened Concrete. Compressive Strength of Test Spec-itish Standards Institution, 2002.390-5, Testing Hardened Concrete. Flexural Strength of Test Speci-tish Standards Institution, 2000.504-4, Testing Concrete. Determination of Ultrasonic Pulse Velocity,andards Institution, 2004.


[19] BS EN 12457-2, Characterisation of Waste. Leaching. Compliance Test for Leach-ing of Granular Waste Materials and Sludge., British Standards Institution, 2002.

[20] A. Neville, J.J. Brooke, Concrete Technology, Longman, Harrow,1987.

[21] H. Uchikawa, S. Hanehara, D. Sawaki, The role of steric repulsiveforce in the dispersion of cement particles in fresh paste pre-pared with organic admixture, Cement Concrete Res. 27 (1996)3750.

Environmental performance and mechanical analysis of concrete containing recycled asphalt pavement (RAP) and waste precast...1 Introduction2 Materials and methodology2.1 Properties of materials used in concrete production2.2 Production of concrete mixtures2.3 Tests and analysis performed

3 Results and discussions3.1 Fresh properties3.2 Compressive strength and density3.3 Flexural tensile strength3.4 Ultrasonic pulse measurements3.5 Leaching measurements

4 Concluding remarksReferences

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