Influence of Oxide Molar Ratio on Size Effect of Geopolymer Recycled Aggregate Concrete

Abstract

Four different size of concrete cube (70 mm3, 100 mm3, 150 mm3, and 200 mm3) of geopolymer recycled aggregate concrete (GRAC) were prepared by replacing cement with geopolymer and natural aggregate with wast concrete. The effect of oxide molar ratio of raw material on compressive strength and its size effect of GRAC was studied.The results show the size conversion coefficient of GRAC cannot adopt the values from the current national standard GB/T50081. The relationship of size conversion coefficient α and oxide molar ratio ε of GRAC was worked out. It was found that the compressive strength of GRAC of all sizes were in line with the Bazant’s size theory. Oxide molar ratio on critical size and critical value of GRAC were calculated.