预拌混凝土早期极限拉应变试验研究

Experimental research on the ultimate tensile strain of premixed concrete at early-age

为较精确得到预拌混凝土早期极限拉应变,利用自行设计制作的轴心抗拉试验装置解决了试件对中困难的问题。对工程中常用的3个强度等级(C20,C40,C60)的混凝土进行4个龄期(3,7,14,28d)的试验研究。研究得出了预拌混凝土早期极限拉应变,并和已有数据进行对比分析;拟合出预拌混凝土早期极限拉应变随龄期的变化规律;得到预拌混凝土早期极限拉应变和立方体抗压、轴心抗拉强度以及抗拉弹性模量的关系。利用文中公式可估算出预拌混凝土早期极限拉应变,为有关技术人员和混凝土规范中关于耐久性的修订提供参考。

To get the precise tensile strain of premixed concrete at early-age, the difficulty of specimen centering was solved by the self, designed axial tension experimental apparatus. The experiment was performed on three different strength grades concrete of C20, C40 and C60 at four ages of 3,7, 14 and 28 days. The ultimate tensile strain at early-age of the premixed concrete was obtained and compared with the existing data. The change relationship of ultimate tensile strain at early-age with the ages was obtained. The relationships between the ultimate tensile strain of the premixed concrete at early-age and the cube compressive strength, axial tensile strength and tensile elastic modulus were proposed. The ultimate tensile strain at early-age of premixed concrete can be estimated by the proposed formula, providing reference for the related engineers and the revision about the durability in concrete standards.