The Non-steam Autoclaved Process Research Of Prestressed High-strength Concrete Piles

At present, the process of prestressed high-strength concrete (PHC) piles production in China basically use steam curing and autoclave secondary hydrothermal curing process, which not only need to add expensive autoclave equipment, curing processes to be accounted for a very long time and takes a lot of resources, piles temperature is high when take out from the boiler, if not effectively to deal with the concrete piles will crack for too large temperature difference. Therefore, to research and develop non-steam autoclaved curing process has very important significance to energy conservation and environmental protection, meanwhile, the process simplifies the production links, In favor of improving prestressed high-strength concrete piles product quality and quantity. This paper systematically studied the non-steam autoclaved curing process of prestressed high-strength concrete piles by means of adjusting the raw material, adjusting the mixture ratio and changing steam curing system and so on. The main studied contents are as follows:Firstly, studied the optimization of raw materials and the mix proportion design. The test results show that:water-cement ratio have the greatest effect on the strength of non-steam autoclaved high-strength concrete, the smaller the water-cement ratio is, the higher the concrete strength is, in order to improve the strength of the concrete, we must try to reduce water-cement ratio of the concrete as much as possible. Followed by sand ratio, there is one of the best sand ratio of prestressed high-strength piles concrete is32%, over and below this percentage will affect the strength. In addition, selected different types of admixtures according to the adaptability between cement and admixtures, and determine use the best self-made naphthalene, which dosage is3.5%. Secondly, studied the effect of different mineral admixtures on non-autoclaved high-strength pile compressive strength, the results showed that:the concrete that adding slag and fly ash after atmospheric pressure steam curing, which activities contribute little to the strength of concrete, can not meet the C80prestressed concrete pile strength requirements. Using self-made mineral admixture can make the prestressed high-strength concrete piles meet the strength requirements without secondary autoclave curing conditions, which strength is91.4MPa.Finally, the effect of atmospheric pressure curing system on prestressed high-strength concrete steam-cured strength are studied, and identifid the best steam curing system on the basis of meet the requirements of the prestressed high-strength concrete steam-cured strength and production processes, specifically:resting for2.5h, heating up for2.5h, constant temperature of10h (80±5℃), cooling for2h, which save great energy but also generate some economic benefits.This paper preliminarily prepared concrete can meet the production requirements of prestressed high-strength concrete piles of C80, which has a significant guiding significance of cost savings and energy consumption reducing.