Karakteristike asfaltnih mešavina sa agregatom od recikliranog betona

Abstract

U cilju implementacije i promocije održivog razvoja u oblasti graditeljstva,sprovedena su obimna eksperimentalna ispitivanja kako karakteristika recikliranogagregata (RCA), tako i karakteristika asfaltnih mešavina sa delimičnom zamenomprirodnog agregata recikliranim. Reciklirani agregat koji je korišćen u istraživanjudobijen je drobljenjem originalnog cementnog betona klase čvrstoće C35/45.U cilju poboljšanja kvaliteta recikliranog agregata, krupan RCA (d>4 mm) jeizložen tretmanima hlorovodoničnom kiselinom (potapanjem u 0.1 mol/dm3 HCl) iubrzanoj karbonatizaciji (koncentraciji CO2 od 4%). Pomenutim tretmanima su umanjoj meri poboljšane karakteristike RCA, pa su dalja ispitivanja uticaja RCA nakarakteristike asfalt betona sprovedena samo za netretirani RCA.Eksperimentalnim ispitivanjima je obuhvaćeno 10 asfaltnih mešavina. Osimkontrolne mešavine, formirane su tri grupe mešavina sa delimičnom zamenom sitnog(0/4 mm), krupnog (4/22.5 mm) i sitnog i krupnog (0/22.5 mm) prirodnog agregatarecikliranim. Svaku grupu su činile mešavine sa tri različita sadržaja RCA: 15%, 30% i45%. Projektovane su asfaltne mešavine za noseći sloj kolovozne konstrukcije AC 22BASE sa ciljanim sadržajem šupljina ispunjenih vazduhom od 5.2%.Glavni deo eksperimentalnog rada je obuhvatio ispitivanje modula krutosti iotpornosti asfalntih mešavina na dejstvo vode, trajnu deformaciju, zamor i nisketemperature. Dobijeni rezultati su pokazali da je moguća primena kompletnog RCA (isitan i krupan agregat); da mešavine sa RCA imaju istu ili bolju otpornost na zamor uodnosu na kontrolnu mešavinu; i da je maksimalna količina RCA u manjoj meriograničena otpornošću na niske temperature.Na osnovu analize dobijenih rezultata razvijena je metodologija za upotrebuRCA kao delimične zamene prirodnog agregata i date su preporuke za dalja istraživanja.

As a part of the implementation and promotion of sustainable constructiondevelopment, large experimental research was conducted. This research included testingof the recycled concrete aggregate (RCA) and properties of asphalt mixtures in whichthis aggregate was applied as a partial replacement of the natural aggregate. Recycledconcrete aggregate used in the conducted experiments was obtained by crushing of theoriginal cement concrete (strength class C35/45).In order to improve it's quality, coarse RCA was exposed to the treatments withhydrochloric acid (by pre-soaking into 0.1 mol/dm3 HCl) and carbon dioxide(accelerated carbonation with 4% concentration of CO2). Mentioned treatments inducedimprovements in the properties of RCA, to a lesser extent. Therefore, only untreatedRCA was used as a partial replacement of the natural aggregate in production of asphaltmixtures.Experimental research was conducted on the 10 different asphalt mixtures. Threegroups of mixtures with RCA were tested in addition to the control mixture. In the firstgroup, only fine aggregate (0/4 mm) was replaced by RCA; in the second group, thereplacement was applied only to coarse aggregate (4/22.4 mm), while the third groupincluded mixtures in which both fine and coarse aggregate were replaced by RCA. Eachgroup included three different contents of RCA: 15%, 30%, and 45%. All asphaltmixtures were designed for the base course AC 22 BASE, targeting 5.2% of airentrained voids.Main part of the experiment consisted of different asphalt mixture’s testing, suchas measurements of: the stiffness modulus, resistance to water, permanent deformation,fatigue and low temperatures. Obtained results show that application of the total (bothfine and coarse) RCA is possible as mixtures with RCA expressed equal or improvedfatigue resistance when compared to the referent mixture. Still, the amount of the RCAused should be limited according to its low temperatures resistance.Methodology for the RCA application, when it is used as a partial replacementof the natural aggregate in asphalt mixtures, was developed based on the presentedresults, together with guidelines for the future research.