Interfacial properties of modeled recycled aggregate concrete modified by carbonation

Modeled recycled coarse aggregates (MRCAs) were designed with different water to cement ratios (w/c) of old hardened mortar (OHM). Each type of MRCAs was modified by carbonation. All carbonated and uncarbonated MRCAs were used to cast modeled recycled aggregate concrete (MRAC) specimens. Push-out tests were conducted to investigate the influence of MRCA carbonation modification on interfacial properties of MRAC. Based on the load-displacement curves, the peak load and peak displacement were mainly analyzed to assess the effect of carbonation modification. The experimental results show that the peak load increased while peak displacement decreased as the MRCA was intensified by carbonation. The effect of carbonation modification was more obvious at a higher w/c. With the increase of w/c of new hardened mortar (NHM) or OHM, the corresponding peak load decreased, whereas the peak displacement tended to increase at first and then decrease. A simulation study was also conducted by software ABAQUS and verified by the experimental results. The parametric study confirms that interfacial properties of MRAC significantly depend on carbonation depth, distribution of OHM and shape of MRCA.