Preventing ASR-induced deteriorations with hydrophobic aggregates- a feasibility study

Concrete deterioration due to alkali-silica reaction (ASR) is one of the main durability concerns. This study explores the feasibility of minimizing ASR-induced deterioration by enhancing aggregates' hydrophobicity. Mortar samples with highly reactive aggregates were prepared. The aggregates were modified through coating with hexamethyldisilazane (HMDS) pretreated fumed silica for improved hydrophobicity. The ASR progression of the specimens prepared with nontreated (control-NHA), washed-coated (WHA), and non-washed coated ag-gregates (HA) was assessed using compressive strength, linear expansion, and dynamic modulus of elasticity tests. In addition, an ASR detection reagent was used to study the extent of deterioration of the mortar specimens. Furthermore, the microstructure and chemical compositions of the ASR-affected mortar were studied using scanning electron microscopy (SEM) and energy-dispersed X-ray analysis (EDX). The research found that although using hydrophobic aggregates may reduce the compressive strength, increasing the hydrophobicity of aggregates can significantly reduce ASR-induced expansion, minimize cracking, and prevent warping.