超低温环境水泥基材料力学性能测试方法研究

Study on testing methods of deformation properties of cement-based materials in cryogenic temperature environment

电阻应变计已通过试验验证可直接作用于超低温环境,并根据相应测试原理可测得材料的线膨胀系数。在借鉴现有测试原理的基础上,提出一套超低温环境电阻应变计测试技术,其能有效区分温度和力引起的变形。加载条件上,通过研发新装置实现了力与温度作用独立同步施加;测试条件上,基于原位补偿构想,实现了在加卸载过程中将力引起的变形与温度作用引起的变形相分离。分析了砂浆在降温至-165℃,应力应变曲线、弹性模量、线膨胀系数随温度的变化规律。试验研究表明:砂浆的应力应变曲线在超低温下呈线性;砂浆的弹性模量始终随温度降低而增加;砂浆的线膨胀系数随温度的降低均存在减小的趋势。试验结果均与现有研究成果规律相同,验证了方法的有效性和合理性。研究结果能为超低温下建筑材料变形性能测试提供重要支撑。

The resistance strain gauge has been verified by experiments to directly act on the cryogenic temperatures,and the linear expansion coefficient of the material can be measured according to the corresponding testing principle.Based on the existing testing principles,this study proposed a set of cryogenic temperature environmental resistance strain gage testing technology that can effectively distinguish temperature and force induced deformation.For loading condition,the mechanical force and temperature action can be applied independently by developing a new device.For test condition,based on the idea of insitu compensation,the strain caused by force and temperature is separated.The stress-strain curve,elastic modulus,and linear expansion coefficient of the mortar with temperature were analyzed after the temperature was lowered to-165℃.Finally,the test results showed that mortar stress-strain curve is linear at cryogenic temperatures.The elastic modulus of mortar always increases with decreasing temperature.The linear expansion coefficient of mortar has a decreasing trend with the decrease of temperature.The test results are the same as the existing research results,which verifies the validity and rationality of the method.The research results can provide important support for the testing of deformation properties of building materials at cryogenic temperatures.