Shrinkage-Compensating Concrete Made With An Expansive Component

Abstract

This paper describes a testing program for shrinkage-compensating concrete made with a proprietary expansive component called CONEX. This testing program allows engineers to estimate the amount of expansion in a concrete structural member based on expansion of small specimens tested in the laboratory. Establishing a relationship between slab expansion and restrained prism expansion will allow the scope of ACI 223.98 (Standard Practice for the Use of Shrinkage-Compensating Concrete) to be extended to include shrinkage-compensating concrete made with a component system that does not form ettringite. During the first phase of the test, trial concrete mixtures were made to determine the amount of expansive component needed to develop an expansion between 0.03% and 0.1% while achieving a minimum concrete compressive strength of 4000 psi. In the second phase, four full-size concrete specimens were cast and the expansive strains in both the concrete and the reinforcement were measured. Based on this research, the relationship between member expansion and prism expansion for the expansive component system were plotted into a figure that could be incorporated into the next version of ACI 223.