UNIT 1 Concrete.pptx

UNIT 1 Concrete;The characteristics of concrete should be considered in relation to the quality required for any given construction purpose. 要讨论任何符合特定用途的建筑物所需要的质量，就必须研究混凝土的特性。 The closest practicable approach to perfection in every property of the concrete would result in poor economy under many conditions. 要使混凝土的每一个特性都趋于完美的最可行的方法，在很多情况下都是不经济的。 ; The most desirable structure is that in which concrete has been designed with correct emphasis on each of the various properties of the concrete, and not solely with a view to obtaining, say, the maximum possible strength. 最理想的建筑物是：在该建筑物中，混凝土的设计恰如其分地强调了该混凝土的各项特性，不能孤立地追求个别的特性指标，比如，最大可能的强度。 ;Although the attainment of the maximum strength should not be the sole criterion in design, the measurement of the crushing strength of concrete cubes or cylinders provides a means of maintaining a uniform standard of quality, and, in fact, is the usual way of doing so. 虽然，在设计中获得混凝土最大强度不是唯一的标准，但是测定混凝土立方体或圆柱体的抗压强度为保持均一的混凝土质量标准提供了一种方法，事实上，通常也是这么做的。 ;Since the other properties of any particular mix of concrete are related to the crushing strength in some manner, it is possible that as a single control test it is still the most convenient and informative. 因为任何特定配合比的混凝土的其它特性在一定程度上都与抗压强度有关，抗压强度作为单项控制试验仍然可能是最简便的和最有益的。 ;The testing of the hardened concrete in prefabricated units presents no difficulty, since complete units can be selected and broken if necessary in the process of testing. 在预制构件中，测试已硬化的混凝土毫不困难，因为测试过程中人们可以挑选完整的构件，如有必要的话，还可破坏这一构件。;Samples can be taken from some parts of a finished structure by cutting cores, but at considerable cost and with a possible weakening of the structure. 可以从已竣工的建筑物的某些部位中采样试验，不过这样做费用昂贵，还有可能减弱建筑物的强度。;It is customary, therefore, to estimate the properties of the concrete in the structure on the basis of the tests made on specimens moulded from the fresh concrete as it is placed. 所以，习惯上在浇灌混凝土时用新拌制的混凝土做成试件进行试验，以估计建筑物的混凝土的特性。;These specimens are compacted and cured in a standard manner given in BS 1881:1970