INTERNAL CURING OF CALCIUM SULFOALUMINATE CEMENT CONCRETE USING LIGHTWEIGHT AGGREGATE

Abstract

Calcium sulfoaluminate (CSA) cement is a very rapid setting, hydraulic cement that releases approximately half as much carbon dioxide during production as conventional portland cement. CSA cement produces concrete with high early strength, excellent durability, and limited shrinkage. This cement also requires approximately twice as much water as conventional portland cement for proper hydration. The introduction of internal curing water from presoaked lightweight aggregate into the mix design allows more time for hydration during the curing process. The additional time for hydration provided by internal curing has the potential for positive effects on the performance of CSA cement concrete. The work described in this thesis examined three CSA cements and portland cement with 0 lb, 5 lb, 7 lb, and 10 lb of internal curing water per 100 lb of cement added to each mix design through the use of presoaked lightweight aggregate. Concrete specimens cast from each mix design were tested for compressive strength, permeability through the Rapid Chloride Ion Permeability test, and length change to measure shrinkage of the concrete. It was determined that the compressive strength of the Buzzi CSA cement concrete was impacted most positively by adding 5 lb of internal curing water. The Komponent® cement concrete exhibited the most improvement in performance from adding internal curing water; it showed an improvement in compressive strength and permeability results and reduced shrinkage. In general, the addition of 7 lb of internal curing water reduced shrinkage for all CSA cements examined. The conventional portland cement was the only cement tested that did not exhibit clear benefits from the addition of internal curing water.