Early-Age Compressive Strength of No-Slump Concrete Taking into Account the Effect of Curing Temperature

Abstract

This paper presents the results of a study carried out to investigate early-age compressive strength of no-slump concrete (including pre-cast concrete and roller-compacted concrete) in the presence of fly ash and the effect of curing temperature. In this study, the used binders include ordinary Portland cement type I and fly ash. The replacement ratios of fly ash were varied from 0%, 15% and 30% by weight of total binder. In order to evaluate the effect of curing temperature on compressive strength, laboratory specimens were cured at isothermal conditions of 30C (considered as an average normal temperature in Thailand), 45C and 70C. Compressive strength results were collected at 6 hours, 12 hours, 1 day, 3 days, 7 days and 28 days. The results of the study reveal that although the presence of fly ash increases consistency of fresh concrete significantly, it delays compressive strength development at early ages. However, at elevated curing temperature, it significantly affects compressive strength development at early ages. Furthermore, there exists an appropriate curing temperature to gain optimal strength at specific ages of concrete. This temperature depends on factors such as water to binder ratio, replacement ratio of fly ash in the binder, etc.