Effectiveness of binary and ternary blended cements of class C fly ash and ground glass fibers in improving the durability of concrete

Abstract

Class C fly ash (CFA) has been used extensively as supplementary cementitious material (SCM) to partially replace cement in concrete. However, to meet the concrete durability demand, such as to mitigate alkali-silica reaction (ASR) or sulfate attack, higher amounts of CFA are required, which results in a slower strength gain and longer setting time. Studies have shown that ground glass fiber (GGF) is quite an effective SCM if it is finely ground. This work explores the performance of binary and ternary blends of GGF and CFA with portland cement. Pozzolanicity of the combinations was first assessed by the Thermogravimetric analysis (TGA) and strength activity index (SAI). Then, drying shrinkage, resistance to sulfate attack, and alkali-silica reaction were evaluated. Results showed that GGF could significantly alleviate the shortcomings of CFA, both in terms of strength and durability, even when GGF is introduced in ternary blends at modest levels.