EFFECTS OF AGGREGATE, WATER/CEMENT RATIO, AND CURING ON THE COEFFICIENT OF LINEAR THERMAL EXPANSION OF CONCRETE

A study to determine the coefficient of linear thermal expansion of concrete was conducted using concrete mixtures prepared with three types of coarse aggregates: porous limestone, dense limestone, and river gravel. A Type II portland cement was used at contents of 508, 564, and 752 lb/cu yd and water/cement ratios of 0.53, 0.45, and 0.33, respectively. The concrete specimens were moist-cured and tested at 28 and 90 days. The concrete made with the porous limestone had the lowest coefficient of linear thermal expansion (5.42-5.80 x 10 to the minus 6 power sq in./deg F), whereas the concrete made with river gravel had the highest (6.49-7.63 x 10 to the minus 6 power sq in./deg F). The concrete made with dense limestone had an intermediate coefficient (5.82-6.14 x 10 to the minus 6 power sq in./deg F). The water-saturated concrete specimens had a lower coefficient of linear thermal expansion than the oven-dried specimens. The coefficient of oven-dried concrete decreased with moist-curing time. No significant difference between the 28-day and 90-day moist-curing was observed in the water-saturated concrete specimens.