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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 (w/c) ratio, and air content were apparent; (4) The amount of air needed to obtain maximum frost resistance of the mortars increased with increasing w/c ratio to a maximum of about 9% air for a w/c 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.
This book forms the proceedings of the international workshop to be held in Essen, Germany. This workshop summarises the conclusion of the technical committee's investigations into the resistance of concrete to freeze-thaw attack, specific in this to resistance with or without de-icing chemicals. It presents the RILEM recommendations on testing the freeze-thaw and de-icing salt resistance of concrete.
This study was conducted to determine if reduction in air content by vibration of a well proportioned concrete mixture of relatively high cement content reduces the frost resistance of the hardened concrete and also to determine the effect of such reduction in air content on compressive strength. One 3/4-in. (19.0-mm) maximum-size crushed limestone aggregate concrete mixture was proportioned to have a compressive strength of approximately 5500 pst (37.92 MPa) at 28 days age. The mixture had an air content of 8 plus or minus %. Various vibration times were used to reduce the air content until the samples had an air content as low as could be practically obtained. Specimens were cast for determining compressive strength, resistance to freezing and thawing, and air void parameters to evaluate the effect of reduction in air content of the concrete on strength and frost resistance.