Laboratory Evaluation of Concrete Mixture Designs Employing Type I and Type K Cement

Abstract

This article focuses on a laboratory materials-testing program that was aimed at: (1) identifying candidate shrinkage-compensating concrete (SCC) mixture designs for possible later field evaluations; and (2) performing mechanical property evaluations of the candidate mixtures under various simulated weather and curing conditions. The SCC mixtures were produced by using a Type K portland cement. Results of the laboratory concrete mixture design, property evaluation, and sensitivity testing verified that SCC mixtures should be viable mixtures for bridge decks to reduce shrinkage cracking. The testing revealed that: (1) time-of-set of SCC was faster than for ordinary portland cement concrete by about 100 min, as was the rate of slump loss; (2) the compressive and splitting tensile strengths of the SCC mixtures were higher than those of conventional concrete mixtures using Type I portland cement; (3) the compressive strengths of concrete mixtures with both the Type K and Type I cements were enhanced by the addition of silica fume; (4) the SCC concrete restrained length bar specimens exhibited significant early (first 7 days) expansion; (5) type K cement restrained mortar bars exhibited ∼4 times more expansion than mortar bars made with Type I cement; and (6) type K cement mixtures are quite sensitive to proper moist curing if they are to achieve proper shrinkage compensation.