早龄期混凝土力学性能试验及其单轴本构模型

Mechanical property experiment and uniaxial constitutive model for concrete at early age

为了研究早龄期混凝土的立方体抗压强度、轴心抗压强度、劈裂抗拉强度、静力受压弹性模量以及单轴受压应力应变曲线的规律,进行了系统的加载试验和试验数据分析.总结了早龄期阶段力学指标随龄期的变化规律以及与立方体抗压强度之间的换算关系,通过拟合相关参数,提出了分段式的受压应力应变全曲线拟合公式,拟合结果与试验数据吻合较好.试验结果表明,早龄期C40混凝土的强度和弹性模量随着龄期非线性增长,7 d是增长变化的分界时点;随着龄期的增长,峰值应变减少,脆性变大;早龄期C40混凝土的单轴受压应力应变曲线与充分养护龄期混凝土形状相似.

In order to study the rule of cube compressive strength,uniaxial compressive strength,splitting tensile strength,static compression elastic modulus and uniaxial compressive stress-strain curves of concrete at early age,the loading test for the system and test data analysis were performed. The change rule of mechanical indexes with the age and the conversion relationship with the cube compressive strength were summarized. Through fitting the related parameters,the sectional fitting formula of compression stress-strain curve was proposed,and the fitting results are in good agreement with the experimental data. The results showthat both strength and elastic modulus of C40 concrete at early age nonlinearly increase with the age.The 7 d is the watershed between growth changes. With increasing the age,the peak strain decreases and the brittleness becomes larger. Furthermore,the shape of uniaxial compression stress-strain curve of concrete at early age is similar to that of full age concrete.