Influence of Basalt Fiber on the Performance of Alkali-Activated Slag with Different Activators

Alkali-activated slag (AAS) is a type of eco-friendly alternative to Portland cement. However, the high brittleness and apparent shrinkage limit its wider application for the constructions. Fiber reinforcement of the AAS is one of the effective ways to mitigate these problems. In this study, the effects of basalt fiber on the microstructure, compressive strength, flexural strength, and drying shrinkage properties of AAS with different activators have been investigated. The alkaline activators with the silicate modulus of 0, 1, and 2 were used for preparing the AAS samples with and without basalt fibers. The results showed that increased silicate modulus resulted in a more compacted matrix around the basalt fiber. The structure of the reaction products in AAS tended to be improved by the addition of the basalt fiber and the change of the C-(A)-S-H structure in the AAS was more obvious in the AAS samples with higher silicate modulus. The basalt fiber was most efficient in improving the compressive and flexural strength of the AAS when the silicate modulus of the activator was 1. The reduction of the drying shrinkage by the addition of the basalt fiber was more significant with the increase of the silicate modulus in activators. This study provides information on the reinforcement effects of basalt fiber on the AAS and facilitates the design and performance improvement of the basalt fiber reinforced AAS.