Title: Critical Air Void Spacing Factors for Concretes Submitted to Slow Freeze-Thaw Cycles

Author(s): Michel Pigeon and Martin Lachance

Publication: Journal Proceedings

Volume: 78

Issue: 4

Appears on pages(s): 282-291

Keywords: air-entrained concretes; air entrainment; compressive strength; concretes; freeze-thaw durability; microcracking; specimens; ultrasonic tests; water- cement ratio.

DOI: 10.14359/6926

Date: 7/1/1981

Abstract:
Non-air-entrained and air-entrained concretes with varying air void systems were submitted to 300 freeze-thaw cycles in air at 100 percent relative humidity, at a freezing rate of 2 C/hr. Length change was used as the main indicator of concrete deterioration. Although almost no scaling was observed, length changes of more than 1 percent were measured on some specimens. For a water-cement ratio of 0.5, the critical air void spacing factor (the value below which concrete will be minimally damaged at 300 freeze-thaw cycles) was determined to be 680 pm, and for a water-cement ratio of 0.6, the factor was 570 pm. These two values, which are in the range of spacing factors of entrapped air voids in non-air-entrained concretes, are in good agreement with the value obtained from Powers’ hydraulic pressure theory for the rate of freezing used in the tests (the calculations are based on the critical value of 250 pm for a freezing rate of 11 C/hr).