Extended mixing processes on early- and later-age of cement systems incorporating fly ash

Abstract

Abstract Specifications that correlate with system performance can “ensure” continual values being added. Most specifications for ready-mixed concrete address limits on discharge time and truck-drum revolution counts. These limits have been developed for conventional concrete. As the uses of supplementary cementing materials (SCMs) become ubiquitous, it is important to determine whether these specifications are applicable to SCMs, that is, systems containing fly ash. This paper reports results of the effects of mixing time and mixer revolution counts on characteristics of lab-made pastes and mortars. The characteristics assessed include time-variant ion concentrations, setting time, flow, compressive strength, porosity, and apparent chloride diffusivity coefficient. Results indicate that with increasing mixing time and mixer revolution counts, mixtures with a replacement of fly ash exhibit improved fresh and hardened characteristics. Fly ash is suggested to adopt in the extended mixing processes of cement systems.