基于温度-应力试验机的大坝混凝土抗裂性综合评价

Crack resistance evaluation for dam concrete based on temperature stress testing machine

为了综合评价早龄期大坝混凝土的抗裂性,以2种不同骨料组合的大坝混凝土为例,采用温度-应力试验机法与常规评价方法,进行了混凝土抗裂性试验.结果表明:由于骨料弹性模量与热膨胀系数的差别,骨料品种对混凝土的抗裂性有着明显的影响;采用开裂温度作为综合评价指标,能够有效地评价不同混凝土的抗裂性;相对于常规单项性能试验而言,温度应力试验涵盖了早龄期混凝土的力学、热学及变形性能的发展全过程,评价结果更为客观,且大大缩短了评价周期.这种试验方法适用于混凝土配合比筛选及抗裂性综合评价.

In order to comprehensively evaluate the crack resistance of early age dam concrete made with two different aggregate combinations, a thermal stress test and a conventional test （i. e. stand- ard test of single parameters of thermal properties, mechanical properties and deformation） were used for evaluation. The test results show that elastic modulus and thermal expansion coefficient of aggre- gate markedly influence the crack resistance of concrete. The crack temperature is reasonably adopt- ed as direct evaluating index to effectively contrast the anti-crack ability of different concrete. It is concluded that the whole development process of the mechanical, thermal and deformation properties of concrete at early age can be monitored by thermal stress test and the evaluation period can be shortened dramatically. This test method can be reliably used to optimize the mix proportion of concrete and comprehensively evaluate the crack resistance of concrete at early age.