Effect Of Freeze-thaw Cycles On Dynamic Mechanical Properties Of Ceramsite Concrete

Effect of freeze-thaw cycles on dynamic mechanical properties of ceramsite concrete by using the static and impact compression experiments are studied in this paper. WAW-2000 universal testing machine is used for static compression test with two kinds of size specimens, 150mm×150mm×150 mm and Φ70 mm×35mm, and with ceramsite volume fraction from 0~45%. The 74 mm diameter SHPB device is used for the impact compression test to cylindrical specimens with 70 mm × 35 mm. Three fire pressures of impact experiment are 0.3MPa, 0.5MPa and 0.7MPa. All specimens with Φ70 mm×35mm have experienced different cycles of freezing-thawing from 0, 10, 20, 30, and 40, respectively.The static experimental results showed that the static compressive strength and elastic modulus of ceramsite concrete is decreased with increased of the ceramsite volume percent. When the ceramsite volume fraction is more than 30%, the compressive strength decreased significantly. Unlike mortar concrete, the size effect of ceramsite concrete is unobviously.The SHPB experimental results showed that the dynamics compressive strength of ceramsite concrete are decreased with the increase of ceramsite volume fraction. The dynamic compressive strength of mortar concrete is significantly greater than the ceramsite concrete in the all of three different fire pressures. Different from the mortar concrete, there is a platform stage in the stressstrain curve of the ceramsite concrete. Namely, with the increased of the strain, the stress-strain curve displayed a clear turning point after the peak stress. After the point the tendency of stress decreased with the increase of strain is weakened significantly. The toughness of the concrete is improved by the increase of volume of ceramsite aggregate.With the increase of freeze-thaw cycles, the compressive strength and elastic modulus of the mortar concrete and ceramsite concrete are reduced. After 40 times freeze-thaw cycles, the surfaces of specimens spalled off seriously and the damage of specimen is increased with the increase of ceramsite volume fraction. At this time the dynamic compressive strength of the ceramsite concrete is almost a half of value of the same specimens with no freeze-thaw cycle. The compressive properties of mortar concrete and ceramsite concrete specimens after the freeze-thaw cycle under the temperature from-20 ℃ to 10 ℃ is obviously lower than one’s under the temperature from-10 ℃ to 10 ℃.