Experimental Study of the Geopolymeric Recycled Aggregate Concrete

Abstract

Aiming to solve the problems caused by the construction and demolition waste and the depletion of natural aggregates, in the present study, both the coarse recycled aggregates and the fine recycled aggregates are used to produce new green concrete with a fly ash–based geopolymer. The mechanical study shows that the reduction rates of the compressive strength, Young’s modulus, and the Poisson’s ratio of the geopolymeric recycled aggregate concrete (GRAC) specimens increase with the increase of the water/cement (w/c) ratio. The Young’s modulus is much more vulnerable to the increase of the w/c ratio than the compressive strength. These significant changes to the GRAC samples could be attributable to the deteriorated properties rendered to the geopolymer by the increase of the w/c ratio. When the minimum ratio of w/c is applied, the fly ash–based geopolymer renders better mechanical properties to the concrete specimens than the ordinary portland cement. With the aid of scanning electron microscopy and nanoindentation, there is no interfacial transition zone well developed between the old cement paste and the new geopolymer/cement paste.