Research On Clogging Process And Restoration Of Permeable Concrete Pavement

As a kind of porous material,permeable concrete is commonly used to alleviate urban ecological problems.However,due to the special pore structure of permeable concrete,it not only has poor mechanical properties,but is also easily blocked by tiny particles in surface runoff.In order to improve the permeable and mechanical properties of permeable concrete,basic tests and blockage tests are designed to simulate the service process.In the basic test,five sets of aggregate particle size and water-cement ratios were set,and specimens were prepared through static pressure forming and natural forming,Studied the changes of water permeability and compressive strength of permeable concrete.The blockage test firstly analyzed the porosity of different depth sections with the help of two-dimensional flat scanning and image recognition technology,and then used 0～6mm stone powder particles,cement mortar particles and soil particles as the blockage material.10 g was a batch,blocked the test piece in batches,and monitored the change of water permeability coefficient.Finally,three cleaning methods: clean water,high-pressure water,and vacuum suction were used to clean the blocked specimens.The main conclusions are as follows:(1)The experiment is improved on the permeable device.Gravity sensor is connected to the computer to record the data and deduce a new formula for calculating the permeable coefficient.The results show that this method not only spend low cost,but also has more stable and smaller data than the way of using ultrasonic current meter.(2)With the increase of the aggregate particle size,the accumulation between the aggregates becomes looser and the bite force becomes worse.Due to the poor tensile strength of the cement paste,when the aggregate is slightly creeping,cracks will occur.Cracks in the structure resulting in poor compressive strength and flexural strength.Although the mechanical properties of large-particle aggregates are poor,the water permeability is excellent.When the aggregate particle size around 9mm～11mm,the water permeability gradually stabilizes.With the increase of aggregate particle size,the dispersion of permeable coefficient gradually increases.(3)As the w/c ratio increases,the fluidity of cement is better,and the dispersion of porosity proportion and permeability coefficient of permeable become more serious.This is because the natural dispersion of the uneven thickness of the paste when the aggregate is wrapped.And when the w/c ratio is low,the hydration reaction is incomplete and the strength of the cement paste is insufficient.When the water-cement ratio is too high,the cement paste is easy to deposit and block.the slurry wrapping thickness of the forming surface is thin,which is easy to appear weak points and reduce the bearing capacity of the structure.When the water cement ratio is 0.29,the compressive strength reaches the peak.(4)Permeable specimens with different water permeability have the highest permeation coefficient loss when they are clogged for the first time,and the permeation coefficient is lossed by 26.7%～55.7% for every 10 g of plugging material added.(5)The cleaning effect of the high-pressure water gun is the best.The soil particles cannot be cleaned by vacuum suction.When washing with clean water,the soil particles are easier to clean than the cement mortar particles,and the blockage formed by the stone powder particles is the most difficult to be cleaned.