Exploring the impact of early strength accelerator on mortar compressive strength and durability with and without heat curing method

This study investigates the properties of concrete early strength accelerators, focusing on setting accelerators (Ca(HCOO)₂), hardening accelerators (KBr), and alkanolamines (TIPA), with applications in concrete road repairs, fast-setting concrete, and bridge connections. The investigation utilizes standard and heat curing methods to assess the early strength accelerator’s impact on slump flow, compressive strength development, water permeability, water absorption, and drying shrinkage. The results show that KBr enhance early compressive strength at both standard and 50 °C curing, while Ca(HCOO)₂ reduces setting time but does not enhance early strength under heat curing. The combination of KBr and Ca(HCOO)₂ significantly improves early strength at the early age of curing. Adding 0.05% TIPA to the 2.0% KBr and 1.0% Ca(HCOO)₂ mix can further enhances early-age compressive strength and long-term compressive strength up to 58 days of curing. Moreover, the results also show that the water permeability and water absorption remain the same when using or not using the early strength accelerator combination and heat curing method. Hence, using a combination admixture of 0.05% TIPA, 2.0% KBr, and 1.0% Ca(HCOO)₂ is suitable for applications in repairing concrete roads and connecting bridges, where high early compressive strength is required within the curing time range of 8 to 12 h. However, it is crucial to note that drying shrinkage values are higher with the use of early-strength accelerator combination and heat curing. Furthermore, comparison between samples with and without the early-strength accelerator combination shows a significant reduction in slump flow after 60 min, when the specimens are remixed for 15 s every 30 min.