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3.1引言在现场,热裂缝的发生取决于两个方面因素,其一是混凝土热变形和其他早期变形;其二是这些变形受到的约束。因此,裂缝的现场评价需要考虑以下两个参数:·混凝土拌和物的开裂敏感性,决定于混凝土组成、配合比和新拌混凝土温度;·边界条件(构件的尺寸、约束程度、温度等)。在过去的10年间,对混凝土拌和物开裂敏感性的了解取得了很大进步。由于工程师们学会考虑热应力和其他早期应力,不仅仅考虑温度,而是充分考虑了混凝土在24h~36h前关键性早龄期的弹性模量和温度发展。大部分的硬化过程和温度发展就发生在这期间。
3.1 Introduction In the field, the occurrence of hot cracks depends on two factors, one is thermal deformation of concrete and other early deformation; the other is the deformation of these constraints. Therefore, on-site evaluation of cracks needs to consider the following two parameters: • Cracking susceptibility of concrete mix depends on concrete composition, mix ratio and fresh concrete temperature; • Boundary conditions (component size, degree of restraint, temperature, etc.). In the past 10 years, great progress has been made in understanding the cracking susceptibility of concrete mixes. As engineers learn to consider thermal stresses and other early stresses, they not only consider the temperature, but also take full account of the elastic modulus and temperature development of the critical early ages of concrete at 24h- 36h. Most of the hardening process and temperature development took place during this period.