Influence of graphene oxide on sulfate attack and carbonation of concrete containing recycled concrete aggregate

Sulfate attack and accelerated carbonation tests were conducted on six concrete mixes made with 100% recycled concrete aggregate (RCA) and 30% fly ash (FA) blended with 70% ordinary Portland cement (OPC). The dosage of both graphene oxide (GO) and graphene oxide ball-milled (GObm) added in the concrete mixes were 0.05% and 0.1% by weight of binders. The percentage change in mass was observed to increase but the residual compressive strength decreases with advancing exposure to sulfate solution. The carbonation depth decreases with increasing percentage of graphene oxide in the mixes made with 100% RCA compared to mix without graphene oxide. However, with increasing exposure to CO2, the carbonation depth was observed to increase for all the mixes. The X-ray diffraction analysis (XRD) was conducted on 90 days old samples exposed to sulfate solution, to confirms the presence (formation) of ettringites and anhydrites. The thermogravimetric analysis (TGA) was performed on 28 days samples exposed to accelerated carbonation in order to understand the variation in degradation process. The porosity and pore size distribution were obtained using mercury intrusion porosimeter (MIP) analysis which was conducted on 28 days cured specimens. (C) 2020 Elsevier Ltd. All rights reserved.