On applying fib Model Code's maturity function for strength prediction of self-compacting concrete containing supplementary cementitious materials

The fib Model Code was originally developed to estimate the early-age compressive strength of concrete based on its 28-day strength. It has recently been adopted to serve as a maturity function for predicting the strength of concrete containing supplementary cementitious materials (SCMs) at various curing temperatures, referred to as the fib Model Code’s maturity function. However, while previous studies have used different maturity functions to calculate apparent activation energy, the fib Model Code specifies only a single fixed value (33.3 kJ/mol) for all materials. This limitation underscores the need for guidance on calculating apparent activation energy within the fib Model Code framework. This study proposes two new approaches for determining apparent activation energy using the fib Model Code. In the first approach, the s parameter in the fib Model Code, originally based on cement type and strength class is extended to account for curing temperature effects on concrete strength, enabling the calculation of apparent activation energy. In the second approach, the apparent activation energy is expressed as a function of both curing temperature and concrete age. These methods enhance the robustness and applicability of the fib Model Code maturity function across a wider range of concrete mixes. The feasibility and accuracy of the proposed methods were validated experimentally using high-strength self-compacting concrete (SCC) mixes with various SCMs, as well as utilising published data. • The fib Model Code’s maturity function was extended to enable the calculation of apparent activation energy. • parameter extended to include SCM and curing temperature effects on concrete strength development. • Apparent activation energy is determined as constant or varies with temperature and concrete age.