Application Researches On Construction Technology Of Post-tensioned Pre-stressed Concrete Bridge

With the rapid development of China’s highway construction, the post-tensionedconcrete structures have been widely used in the project. In pre-stressed concrete structure,pre-stressing tension of high-stress state is quite sensitive to corrosion. Once corrosionhappened the speed will be greatly accelerated compared to that of no stress state. It is likelyto cause the section damage of pre-stressed reinforcement corrosion site, leading to rapidfailure of the pre-stressing force, a direct threat to the safety and durability of pre-stressedconcrete structures and components. Through studying and fully understanding the situationand development trend of post-tensioned pre-stressed concrete technology in domestic andinternational fields, the author established and formulated the theoretical calculation methodfor plugging position in pre-stressed concrete bridge cement slurry, the technology of HDPEcorrugated plastic pipe and post tensioned pre-stressed concrete vacuum grouting technology,which are suitable and could be applied to the Company.The contents of the specific work and the results are as follows:1. Using vacuum grouting techniques and technology, especially HDPE combined withvacuum grouting technology, could reduce the water-cement ratio in the grout perfusion,eliminate the pore and slurry bubble mixed within the water, decrease the phenomena ofpores and bubbles mixed in the slurry and guarantee the satiation, density and strength ofgrouting. The pressure drop values in the test was determined by the actual conditions of thesimulation scene, producing6corrugated pipes (HDPE) of the same proportion and thelength making the root immersed in water to simulate concrete pressure of a vacuum for30%(-0.03MPa),40%(-0.04MPa),50%(-0.05MPa),60%(-0.06MPa),70%(-0.07MPa) and80%(-0.08MPa) in the grouting test, through the observation of bubbles within the pores,grout bleeding rate and cutaway body to measure the strength of the7days to determine asuitable vacuum value.2. It could be known by the existing pre-stressed tension theory that the elongation andtheir corresponding stress are of direct proportion except under the process of0.15бcon(controlled stress). With this theory the plugging position of water and mud could bedetermined, which is convenient for construction enterprises to do local treatment and repairfor the beam.