STRESS-STRAIN BEHAVIOR IN TENSION AND COMPRESSION OF CONCRETE DAMAGED BY FREEZING AND THAWING CYCLES

摘要

It has been shown by field observation and laboratory testing that the using air entrainment can protect concrete from freezing and thawing deterioration. Freezing and thawing cycles cause the internal cracking in concrete and surface scaling. The mechanical properties of concrete, such as strength, stiffness, and deformation capacity are affected by expansion in the material microstructure that is the overall effect of cracking within the aggregate, at the interface, and in the matrix which is caused by both freezing and thawing cycles and application of mechanical load. In this paper, the tension softening, stiffness degradation, and stress-strain model of concrete damaged by freezing and thawing cycles are presented. In order to see stress-strain curves mechanical loading is necessary. Tension softening is analyzed by means of the three point bending test of notched beam specimens. Concrete can still transfer tensile stress even it has severe internal damage due to freezing and thawing exposure. The mechanical properties for concrete with and without using air-entraining agent are compared.