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Early-age thermal cracking and delayed ettringite formation (DEF) are short-term and long-term major issues to the durability of mass concrete and require a high level of consideration in the development of a suitable concrete mix design in placement and curing strategies, particularly in mixes of high cement content. Where DEF risk proves to be significant, contractors are required to adopt risk mitigation strategies including lowering concrete's temperature during placement by adding cool water or ice, for example, to the mix, embedding cooling pipes in the cast element and/or sequential placement of the concrete. These strategies can be implemented at different levels, as needed, to minimise the risk of cracking and DEF. Determining the most suitable and cost-efficient risk mitigation strategy, however, together with its implementation, is a complex task that requires consideration of each complex strategy under project-specific conditions. While a significant research effort has been invested to develop an improved understanding of the effectiveness of different early age thermal cracking and DEF risk mitigation strategies, the lack of reliable models capable of simulating and comparing the effectiveness of all scenarios remains elusive and considerably limits the ability of the practitioners in identifying the optimal approach. This paper presents a Multiphysics model developed to predict the effect of early-age thermal cracking and DEF risk mitigation scenarios. The model is validated using four real-life project Case Studies and is demonstrated to provide reliable results. In addition, the paper studies the comparative effectiveness of key risk mitigation strategies and the important parameters influencing their effectiveness.

The Australian Standard accelerated mortar bar test (AMBT) method, AS 1141.60.1, adopts the expansion limits at two exposure periods to classify the alkali silica reactivity (ASR) of aggregate. This was a first step toward the use of ‘reaction kinetics’ or ‘rate of reaction’ to detect and classify alkali silica reactivity. The AS 1141.60.2 concrete prism test (CPT), on the other hand, uses a single expansion limit at one year to classify ASR. This paper examines the validity of the use of reaction kinetics, evaluated from the AMBT expansion data, to gauge and classify the reactivity. This may enable a better quantification of the degrees of reactivity and a more fundamental approach to ASR mitigation