Lightweight Aggregate Concrete Crack Resistance

Lightweight aggregate concrete (LWAC) is one of concrete that use small density lightweight aggregate instead of normal aggregate. Compared with normal concrete, LWAC have many characteristics, such as light, temperature containing, fire-resistant , durability, smaller volumetric deformation , anti detonation and notable economic and technical benefit. Thus, it is of important significance to pay attention to the study on the cracking and mechanical properties in order to promote the progress of LWAC and direct concrete construction practice.Characteristic of plastic shrinkage cracking of concrete made of high strength haydite concrete made from shale as coarse aggregate and the stress-strain properties of the prestressed-beam. Ie could be concluded as following:1 .When the cement was same in per cubic meter, and the ration of quantity of water to cement (W/C) was between 0.3 and 0.4, concrete shrinkage reduces with the increase of w/c.2.To a certainty of content of gelling material, the shrinkage of the fresh concrete increase with the increase of w/c.3.The effect of slag and fly ash on shrinkage was related to quantity of them.4.Water absorption of lightweight aggregate in concrete and the absorbed water curing of lightweight and good interfacial zone between lightweight aggregate and cement paste made LWAC crack resistance.5. LWAC have good frost resistance.6. For the same strength level, the crack resistance under loading superiors than the normal concrete.7.The cracking load of Pretressed LWAC is larger than calculating value and in the working load range. Structure conformity with cross-section assumption.8.Compared with the computing result, the trial value approaches to the result of the finite element, and the result of the code is more safe.