Investigation of Frost Resistance of Mortar and Concrete.

Specimens from 12 mortar mixtures and one concrete mixture were tested for frost resistance by acccelerated freezing-and-thawing tests and by dilation, for compressive strength, for freezable water FW, and for weight changes after each of 8 different treatments. One variable of treatment was age of continuous moist curing the other was age together with cyclic fluctuation of water pressure to simulate the conditions that would affect concrete at a low level in the Eisenhower Lock of the St. Lawrence Seaway among the results of these tests were 1 Cyclic pressure treatment did not cause critical saturation to develop in most of the test specimens, including those most like the Eisenhower Lock concrete 2 The concrete mixture which simulate the concrete in Eisenhower Lock with the large aggregate removed was frost resistant 3 The usual relationships between frost resistance and variables of age, compressive strength, water cement wc ratio, and air content were apparent 4 The amount of air needed to obtain maximum frost resistance of the mortars increased with increasing wc ratio to a maximum of about 9 air for a wc ratio of 0.8 by weight and 5 Data indicated that FW is not a useful index of frost resistance for air-entrained mortar or concrete mixtures.