Test Of Deterioration Of Concrete Compressive Strength Under Dry-Wet Cycles

The durability of concrete structures has become a hot research field in civil engineering circles both at home and abroad.The early-age concrete structures throughout the country are affected by the dry and wet cycle environment to different degrees.Therefore,the dry and wet cycle environment is one of the important factors that affect the durability of the concrete.In this study,six concrete grades?C15,C20,C25,C30,C35,C40?were used as the research object to establish an increase in the dry-wet cycle time of concrete under dry-wet conditions.The relationship between cube compressive strength.The main research results of the paper are as follows:1.The rebound strength test of concrete under different wetting and drying cycle times was carried out.When the concrete strength was less than C20,the concrete rebound value reached its maximum in dry and wet cycle 180 days?90 times?,and 300 days in dry and wet?150 times?.The rebound value decreases slightly;when the concrete is greater than C20,the rebound value of the concrete is also rising in wet and dry weather for 300 days?150 times?.2.The concrete strength test under different wet and dry cycle time was tested by ultrasonic method to obtain a concrete test block with strength class less than C20.The ultrasonic sound speed value gradually decreased as the dry and wet cycle time increased.The concrete test block with strength class greater than C20 was followed.With the increase of the wet and dry cycle time,the ultrasonic sound speed value increases first and then decreases.In the dry and wet cycle 180 days?90 times?,the sound speed value reaches the maximum value,and the sound speed value is obvious in the wet and dry cycle 300 days?150 times?.decline.The compressive strength values of concrete and ultrasonic sound velocity values have the same tendency.3.Through the test of concrete strength at different positions of the sluice:Dry area intensity>Water level soaking area intensity>Water level floating area intensity.The surface porosity of the floating area of the water level is greater than the internal porosity,and there is a gradient from the outside to the inside.4.Inverse regression analysis method is used to obtain the strength curve of the ultrasonic inverse rebound fusion method for concrete under wet and dry environment:f_cu^c=0.1499v^0.7463R¹.1956e^0.064d?gravel?...