EXPANSIVE CEMENTS IN THE UNITED STATES--A THREE-YEAR REVIEW

PORTLAND CEMENT CONCRETE SHRINKS WHEN IT DRIES AND THIS SHRINKAGE CAUSES CRACKING. EXPANSIVE CEMENT CAN ALLEVIATE THIS PROBLEM. TWO MAJOR FACTORS THAT AFFECT THE EXPANSION RATE AND AMOUNT OF EXPANSIVE CEMENT REQUIRED ARE TEMPERATURE AND THE WATER-CEMENT RATIO. MAJOR FACTORS THAT CONTRIBUTE TO THE PERFORMANCE OF EXPANSIVE CEMENT CONCRETE ARE: CEMENT CHEMISTRY AND PHYSICAL PROPERTIES INCLUDING TRICALCIUM ALUMINATE, TRICALCIUM SILICATE, FINENESS, GYPSUM CONTENT, WATER-CEMENT RATIO, TEMPERATURE, RESTRAINT, AGGREGATES, CURING STRENGTH AND MIXING TIME. IT IS CONCLUDED THAT EXPANSIVE CEMENT IS NOT A CURE FOR THE PROBLEM OF CRACKS IN CONCRETE. IT CAN ATTEMPT TO ASSIST IN THE ELIMINATION OF DRYING SHRINKAGE CRACKING. IT WILL NOT COVER UP FOR POOR SUBGRADE PREPARATION OR POOR CURING CONDITIONS. THE ADVANTAGES OF SHRINKAGE COMPENSATING CEMENT SHOULD NOT BE USED AS AN EXCUSE FOR POOR CONSTRUCTION PRACTICES, BUT WHEN USED WITH KNOWLEDGE OF ITS POTENTIAL IT CAN BENEFIT THE COMPETITIVE POSITION OF THE CONCRETE INDUSTRY.