关于桥梁施工外文翻译---桥梁中大体积混凝土的水化热与裂缝.doc

关于桥梁施工外文翻译---桥梁中大体积混凝土的水化热与裂缝 Hydration heat of mass concrete in the bridge and cracks In recent years, large-scale bridge construction increasing number requires some suspension bridge anchorages and bridge pile cap due to the construction, infrastructure using the geometric dimensions of the design, the concrete construction of its huge volume of $ 10,000 to tens of thousands of cubic meters, compared with reinforced concrete, its structure is thick, concrete volume, complex engineering conditions (usually cast mostly underground or semi-underground building) construction technology requires high heat of cement hydration is easy to make the structure of temperature and shrinkage deformation. Quality problems in the bridge construction process, there have been many bridges in mass concrete works, the normal use and durability of these problems will project a different degree of harm. 1.The main reason a large volume of concrete cracks The occurrence of cracks of large concrete structures is caused by a variety of factors, the main factors for various types of cracks are as follows: 1.1 hydration heat of cement hydration process in the evolution of considerable heat, and are concentrated around 7d after pouring, the general per gram of cement can release about 500J of heat, if the cement content 350kg / m ~ 550kg/m3 to calculated per cubic meter of concrete will release 17500KJ ~ 27500, so that the internal temperature of concrete increased (up to about 70 ℃ or even higher). Especially in terms of mass concrete, this phenomenon is more serious because of the different thermal conditions inside the concrete and the surface of the concrete center temperature is high, the temperature gradient is formed, the compressive stresses inside the concrete, the surface tensile stress, when the pull stress exceeds the ultimate tensile strength of concrete when the concrete surface will crack. 1.2 Shrinkage of concrete indurations in the air v