Evaluation of a Chemical Technique to Determine Water and Cement Content of Fresh Concrete

Abstract

This report presents information obtained from an evaluation of a chemical procedure for determining the water and cement content of a concrete in the plastic state. The procedure uses chloride ion titration to determine water content and flame photometry (calcium signature) to determine cement content. This study evaluated the procedure to determine if it could be used to estimate concrete strength potential and to define to what extent test results are influenced by aggregate type, aggregate moisture conditions, aggregate absorption capacity, concrete mix proportions, mix time, and time of sampling. The fieldworthiness of the system was also evaluated. Results indicate that the procedure can rapidly (approximately 15 min) determine the water and cement content of fresh concrete and that it can be used to predict strength potential with an accuracy equal to that of predicting strength from known mix proportions. Aggregate type was the only major concrete parameter that significantly influenced test results. Although aggregate moisture condition, mix proportions, and length of mixing time also influenced test results, their influences were minor. The field tests have indicated that the system is fieldworthy and mobile.