Insights in the chemical fundamentals of ASR and the role of calcium in the early stage based on a 3D reactive transport model

Abstract

Prediction of alkali silica reaction is still difficult due to the lack of a comprehensive understanding of its chemical fundamentals. In-site experimentally revealing the fundamentals is not realistic as ASR shows over several years or even decades and is affected by many factors. In this paper, by utilizing a 3D reactive-transport simulation model at microscale, we have numerically explored the fundamentals of ASR in the early stage under the influence of reactive silica fraction, alkali concentration, silica disorder degree and aggregate porosity. Based on the simulation results, the chemical sequences of ASR, the initial location of ASR products, the mechanism behind and the role of calcium under the influence of the above factors are elaborated. Furthermore, a comprehensive mechanism to explain the pessimum reactive aggregate content is derived. The results of this paper give some insights about ASR in the early stage such as the initial expansion locations.