Study On Frost-Heave Stress And Thermal Stress Of Concrete Under Freezing Condition

The damage and destruction of frozen concrete used in building project is unavoidable problem in the cold area, concrete would bring out frost-heave stress and thermal stress at negative temperature especially, making many tiny flaws and damaging quality of project seriously. So it is very significant that we measure the frost-heave stress and thermal stress of concrete under freezing condition, then in comparison with the damage of frozen concrete.This paper studied distinguish between the mechanical properties of concrete with different mixing proportions (two W/C ratio, two mineral additives) were cured for 28d in normal condition at -20℃, and the mechanical properties of concrete specimens at normal indoor temperature. The mechanical properties include cubic compressive strength, flexural strength, splitting tensile strength. The paper studied the frost-heave stress and thermal stress of hardening concrete with different mixing proportions cured for 28d under freezing condition, then discussed the relation of them and the damage of frozen concrete.The results of experiments show out: the frost-heave stress of normal concrete with low W/C ratio was more small than the frost-heave stress of normal concrete with high W/C ratio under freezing condition. Meanwile, the frost-heave stress of all concrete with different W/C ratio decreased with the adding of mineral additives, the decreaseing extent of concrete with high W/C ratio is more bigger between them. The adding of mineral additives reduced the loss of mechanical properties of concrete relative to normal concrete. We simulated the thermal stress field of concrete under freezing condition by finite sofeware ANSYS. The result indicate: the SX( X axis radial) thermal stress of concrete with low W/C ratio was more large than the SX thermal stress of concrete with high W/C ratio, the changement of the SX thermal stress of all concrete with different W/C ratio was less after adding mineral additives. The SX thermal stress of concrete compared with splitting tensile strength couldn't reach the limiting tensile strength, so didn't create damage.