Effect of GGBFS Content and Curing Temperature on Early-Age Strength and Maturity-Based Modeling of Concrete

This study investigates the early-age compressive strength development of concrete incorporating ground granulated blast-furnace slag (GGBFS) under varying water-to-binder (W/B) ratios (35%, 45%, and 55%) and curing temperatures (5 °C, 20 °C, and 35 °C). Concrete mixtures were prepared with 0%, 20%, and 40% GGBFS replacement levels, maintaining a constant slump of 180 mm. The influence of GGBFS on fresh properties was evident, as higher GGBFS content reduced the demand for high-performance air-entraining water-reducing admixture (AEWR) by up to 72% at 40% GGBFS and W/B of 35%. All mixtures maintained target air content within 4.5 ± 1.5%. The Nurse-Saul maturity method was applied to determine the datum temperature T0 (The minimum temperature required for the degree of maturity to increase) for early-age strength prediction. The optimal T0 was found to be -3 °C for both OPC and GGBFS-blended concretes, replacing the conventional -10 °C value. Compressive strength predictions were conducted using Plowman, Logistic, and Gompertz models within the 5-10 MPa range. The Plowman and Gompertz models predicted early-age compressive strength with an error of approximately 10% in the 5-10 MPa range. In the lower strength range of 3-5 MPa, the Gompertz model exhibited superior predictive performance, with prediction errors 0.5-1 MPa lower than those obtained using the Plowman model. These findings will help in enhancing the maturity method's reliability for low-temperature or time-constrained construction and support the use of GGBFS as a sustainable cement replacement. The study offers practical insights into optimizing early-age performance in blended cementitious systems.