STRESS-STRAIN RELATIONSHIP OF CONCRETE AFTER FREEZING-THAWING CYCLES

In order to investigate the stress-strain relationship of concrete after freezing-thawing cycles, three series of prisms concrete specimens with water-cement ratio of 0.6, 0.54 and 0.48 respectively were exposed to rapid freezing-thawing in water following the requirement of Chinese standard GBJ 82-85. Then the axial compressive loading tests were carried out to obtain the complete stress-strain curves of concrete using INSTRON 8506 test system. The test results of the 85 specimens show: with the increase of freezing-thawing cycle number the concrete stress-strain curve becomes more flat, the peak stress decreases and the peak strain increases; with the same number of freezing-thawing cycle, the reduction of the peak stress and the increase of the peak strain are more serious for lower strength concrete. Based on the test results the complete stress-strain curve equations for frozen-thawed concrete are suggested. The equations are suitable for concrete with cubic strength of 30 Mpa-50 MPa.