After formwork dismantling,the structure is shaped to inverted arch with stored stress and deflection,and concrete crack meets the code requirement,resolving the deformation and crack problems of concrete beams with height-to-span ratio of 1/23.
It analyzes reasons and mechanism of concrete crack, control measures for design means and construction technology are introduced to prevent or reduce cracks, which can improve durability and appearance quality of structure.
The results was to approve that effect of SRA by paint was as same as by inner-dosage,and the latter can improve the workability of fresh concrete by unstable air-entrainning,which can improve the stability of HPC further, and promote effectively shrinkage-reducing performance and decrease the risk of concrete crack resulted from inhomogeneous expansion,while expansion agent was used with combination.
It illustrates causes of mass concrete crack, and puts forward prevention measures from proportion design、selection of primary material、adding admixture、construction method and maintenance, which to control construction quality of mass concrete structure.
This article incorporates with the practice for construction of Large-Volume concrete of Raft foundation of Nanping Times Mansion,analyses the mechanism of Large-Volume concrete crack,introduces crack control measures of Large-Volume Concrete and its practical effect
The cause that gave rise to in the concrete crack has been analysed in this text,having resisting each component part splitting the waterproof agent to have carried on experiment research on the more inferior foundation to YNB,as well as the high capability of soak YNB resists the sclerosis ability capability and durability to split the waterproof agent has been in progress research,and has had the application in the engineering,and has gotten better technology,economic effect.
By application of ready mix pumping concrete in all kinds of projects, the paper discusses several aspects from improving ready mix concrete quality, reducing concrete contraction oneself, compounding tiny expansion concrete to remove concrete crack, preventive measure of mass concrete heat of hydration causing crack, preventive measure of desiccation fissure of concrete surface and so on, and summarizes methods and measures of preventing and controlling cracks of ready mix pumping concrete.