Steam Curing of Precast Concrete Containing Limestone Filler — Evaluation of Early-Age Strength

摘要

The precast concrete industry is considering approaches with respect to mix design constituents and manufacturing methods to reduce the environmental impact of concrete products without compromising the desired properties and performance. The specific focus of this study is to examine the effect of using limestone filler and ground granulated blast furnace slag as cement replacement on the early age (one-day) compressive strength of steam cured precast concrete. Although it is known that a potential risk of incorporating such material may compromise the rate of hydration reactions and result in an inferior compressive strength gain which could delay demolding and prestressing operations reducing the rate of product production. This study explores the interplay between steam curing variables and mix design constituents to identify the variables that most significantly control the one-day strength of precast concrete. Key outcomes of this research reveal that the GU (general use) cement content (504 - 600 kg/m~3) [31.5-37.5 lb/ft~3], and the percentage of slag (up to 16.7%) has a greater effect on the one-day strength than does the cementitious material content for GU-slag blends, the stream curing duration (16-24 hours), the type of cement used (high early (HE) or GU), and the steam curing temperature (60-70°C) [140-158℉].