The Influence of Crystalline Waterproofing Admixtures on ASR Development Mechanisms and Kinetics

Alkali-Silica Reaction (ASR) is one of the most harmful distress mechanisms affecting the durability and serviceability of concrete infrastructure worldwide. Its development leads to microcracking, loss of material integrity and functionality of the affected structure. It has been verified that some products, such as crystalline admixtures, could enhance the healing properties of concrete, thus presenting an interesting “physical” solution for durability-related distress due to ASR. However, their behaviour under the critical development of physicochemical distress mechanisms is relatively unknown. This paper aims to evaluate the influence of crystalline admixtures on ASR development mechanisms and kinetics. Therefore, this study is divided into two phases. In the first phase, concrete cylinders containing non-reactive aggregates and a commercially available crystalline admixture developed based on Krystol technology were fabricated. After 28 days of curing at 20℃ and 100% RH, pre-loaded using up to 90% of their corresponding compressive strength, then microscopic analysis was performed. Afterwards, the samples were restored at the same curing conditions for 90 days and reevaluated microscopically. In the second phase, concrete mixtures containing highly reactive coarse aggregates, the commercially available and modified versions of the CA, were fabricated, exposed to ASR development, and evaluated over time. At specific time points, microscopic tests were conducted to appraise ASR-induced development. Results show that CAs decreased ASR-induced expansion and changed its mechanism. The data suggest that the concrete's enhanced self-healing ability impacted ASR development.