混凝土早期变形与开裂敏感性试验研究

利用国内最新研发的温度-应力试验机针对混凝土早期的变形性能及开裂行为进行了一系列研究,分析了几类典型混凝土早期温度、应力、变形的发展规律,并由此得到混凝土早期弹性模量、热膨胀系数发展规律。研究表明:混凝土的变形发展可以分为早期收缩、膨胀、收缩至开裂三个阶段;混凝土的水化热温升与开裂并不直接相关,应同时考虑混凝土内部温度和应力的发展过程;开裂温度作为综合指标,能够有效评价混凝土的总体开裂敏感性;适当的化学外加剂和矿物掺合料能够改善混凝土的早期变形和力学特性。

Experimental Research on the Deformation and Cracking Sensitivity of Concrete at Early Ages

By using the newest temperature-stress testing machine,the deformation performances of concrete at early ages were studied and the evolution rules of temperature,stress,deformation and the elastic modulus,the coefficient of thermal expansion at early ages were achieved.The research indicates that the deformation development process of concrete can be divided into three phases: early age contraction,expansion and contraction.Temperature rising due to hydration heat is not directly correlated with cracking,but the temperature and stress evolution process should be taken into consideration at the same time.Cracking temperature can be used to assess the cracking resistance of concrete efficiently.Proper chemical admixtures and mineral compositions can improve the mechanics and deformation properties of concrete such as elastic modulus,which is very indicative in practice.