Drying shrinkage of alkali-activated fly ash/slag blended system

The drying shrinkage of alkali-activated fly ash/slag (AAFS) is an important engineering property for the control of cracking when AAFS is utilized as a building material. In this study, results of drying shrinkage of AAFS pastes with different fly ash content and activator concentrations were presented. The weight loss of samples during the drying process was monitored. The pore structure and free water content of AAFS pastes were measured. The results showed that AAFS pastes with 30 and 50 w.t.% fly ash content exhibited a lower drying shrinkage than alkali-activated slag, while the drying shrinkage of AAFS pastes with 70 w.t.% fly ash content was the largest among all the mixtures. Besides, AAFS pastes with higher activator concentration exhibited a higher drying shrinkage. But there were no clear correlations between weight loss, pore structure and the drying shrinkage. It was assumed that other factors affect the drying shrinkage of AAFS.