工程管理外文文献翻译混凝土施工.doc

外文文献翻译 () 英文原文 Concrete Construction matter T. Pauly, M. J. N. Priestley Abstract Viewed in terms of accepted practices, concrete construction operations leave much to be desired with respect to the quality, serviceability, and safety of completed structures. The shortcomings of these operations became abundantly clear when a magnitude 7.6 earthquake struck northern Paki-stan on October 8, 2005, destroying thousands of buildings, damaging bridges, and killing an esti-mated 79,000 people. The unusually low quality of construction operations prevalent was a major cause of the immense devastation. Keywords: Concrete Placing Curing Construction Technology Placing Concrete If concrete is placed in the surface, the sur-face should be filled with water sufficiently to prevent it from absorbing the concrete of its water. If fresh concrete is to be placed on or nearby to concrete that has solidified, the surface of the placed concrete should be cleaned absolutely, preferably with a high-pressure air or water jet or steel-wire brushes. The surface should be wet, but there should be no much water. A little quantity of cement grout should be brushed over the whole area, and then followed immediately with the application of a 1/2-in Layer of mortar. The fresh concrete should be placed on or against the mortar. In order to decrease the disintegration re-sulting from carriage after it is placed. The con-crete should be placed as nearly as probably in its final point. It should be placed in layers to permit uniform compaction. The time interval between the placing of layers should be limited to assure perfect bond between the fresh and previously placed concrete. In placing concrete in deeper patters, a ves-sel should be used to limit the free fall to not over 3 or 4 ft, in order to prevent concrete disintegra-tion. The vessel is a pipe made of lightweight metal, having adjustable lengths and attached to the bottom of a hopper into which the concrete is deposited. As the patters