Activation Energy of Alkali–Silica Reaction and Dilatometer Method

Abstract

Alkali–silica reaction (ASR) continues to be a detriment to the long-term performance of concrete. Certain initial conditions related to material alkalinity, aggregate reactivity, humidity, and temperature conditions are known to initiate ASR. A key factor in the prediction of ASR in concrete over time is the reactivity of the aggregate, but current test methodology is largely simulative in nature and yields mainly empirical results that apply to only a narrow band of conditions, and leave many questions as to whether these methods have any relevance to concrete performance under field conditions. Improvement can be found by using a performance-based approach that can address the ASR potential of concrete at levels of alkali, temperature, and moisture that are realistic and representative of actual field conditions. In the present study, the concept of ASR-related activation energy is introduced as a representative single parameter of the ASR. An attempt has been made to introduce the dilatometer test method as a part of a performance-based testing protocol for predicting potential ASR aggregate reactivity in terms of activation energy. It is observed that this new test method can categorize minerals and aggregates based on their reactivity within a short period. The use of the activation energy provides a unique parameter for evaluating ASR susceptibility of minerals and aggregates.