Title: Frost Susceptibility of High-Strength Concrete

Author(s): Robert E. Philleo

Publication: Symposium Paper

Volume: 100

Issue:

Appears on pages(s): 819-842

Keywords: admixtures; concrete durability; drying; freeze-thaw durability; high-strength concretes; reviews; silica; tests; water-reducing agents; General

DOI: 10.14359/3708

Date: 4/1/1987

Abstract:
Recent developments have made a new generation of high-strength concrete a viable material for routine construction. The two principal developments are high-range water-reducing admixtures, which permit the placement of concrete of very low water-cement ratio, and silica fume, a pozzolan of extremely high fineness. There are those who argue that high-strength concrete is of such a quality that entrained air is unnecessary. The resistance to freezing is directly dependent on the concrete's capacity for and its probability of containing freezable water if ambient conditions permit continuous hydration for a long period of time so that all the available space is filled with hydration products; or, short of complete space filling, they may become so impermeable that saturation by water is unlikely in most natural exposures. High-range water-reducing admixtures do not alter the pore structure of cement paste; they merely extend traditional cement technology into a range of low water-cement ratios that were previously impractical. The addition of silica fume does alter the pore structure and places more of the pore volume in pores that are so small that water cannot freeze in them at ordinary atmospheric temperatures. It offers some hope of achieving frost resistance without entrained air. The normal test for evaluating frost resistance, ASTM C 666, exposes specimens to freezing at an intermediate level of maturity with no opportunity for drying by loss of water to the surroundings prior to test and exposes them to a very rapid freezing cycle. High-strength specimens without entrained air that may ultimately become durable cannot be expected to do well in the test. While the test is excellent for assessing the frost resistance of young saturated specimens to severe exposure, the resistance of mature specimens to more typical exposures might better be assessed by altering the age-at-test and specimen-conditioning requirements in C 666 or by replacing it with a critical dilation test such as ASTM C 671.