Mechanical and Physical Characterization of Glass FIber Reinforced Alkali-Activated Cementitious Materials

Abstract

Alkali-activated cementitious materials (AAC) have long been studied as sustainable alternatives to concrete made with Ordinary Portland Cement (OPC). Knowledge of the interaction between AAC and traditional concrete additives is necessary to understand the suitability of AAC for a variety of applications. Glass fiber reinforcement is often used in OPC-based concrete as a cost-effective means of improving concrete’s tensile strength, toughness, ductility, and resistance to drying shrinkage and surface microcrack propagation. This research looks into whether glass fiber reinforcement could be employed similarly in AAC systems. A 50/50 blend of fly ash and slag was activated with commercial sodium silicate solution. The 28-day compressive strength, split-tensile strength, elastic modulus, modulus of resilience, and ultimate deformation of this concrete blend with varying dosages of short glass fibers are reported. An equivalent cement mix was created to analyze the drying shrinkage and surface microcrack area over an 8 hour period. Various theories are presented to explain the resulting trends among these properties. It was found that a 1 wt.% fiber dosage was most effective at improving the split-tensile strength, resilience, and ductility. This dosage also decreased the extent of drying shrinkage and drying-induced surface microcracking. While this mix suffered from a slight reduction in compressive strength likely caused by its compromised workability, the addition of a polycarboxylate superplasticizer counteracted this effect. Due to its excellent mechanical and physical properties, the glass fiber reinforced AAC studied here could be considered a suitable alternative to the OPC equivalent currently used in the field.