Physical and mechanical characteristics of limestone after high temperature

The laboratory tests are performed to study the physical and mechanical properties of Jiaozuo limestone after undergoing different high temperatures.The temperature varies in the range of 100℃,200℃,400℃,600℃ and 800℃.The scopes of this study include the description of apparent shape,the measurement of volume,mass and density and the detection of longitudinal wave and shear wave of limestone.The peak stress,peak strain and Young's modulus of limestone are also investigated under the uniaxial compression.The factors of degradation of limestone under high temperatures are discussed.The test results show that the high temperatures lead to variation of the apparent shape for limestone.The temperatures do not obviously affect the physical and mechanical properties of limestone below 400℃.The volume of limestone reduces slightly below 200℃,but increases obviously over 200℃.Meanwhile,the density of limestone decreases gradually with the increase of the temperatures.As the temperatures increase,the S-wave velocity and the P-wave velocity for limestone generally decrease.The variation of ratio of wave velocity for limestone is irregular after high temperature.The dynamic elastic modulus of limestone after high temperature decreases with the increase of the temperatures.When the temperature is above 400℃,the mechanical properties of limestone exhibit deterioration with the increase of the temperature,and the peak stress and Young's modulus of limestone decrease to different extents.The variation of the peak strain of limestone is unconspicuous before 800℃.The thermal stress,variations of mineral formation and microstructure due to the temperatures result in the variation of physical and mechanical properties and degradation of limestone.