Mix Design Of Pervious Concrete And Its Application Research On Road Performance

Pervious concrete is a new kind of porous ecological concrete material.This paper mainly studies the preparation process,working performance,mechanical and pervious performance,durability,plugging and recovery of pervious concrete,tests the compressive strength,flexural strength,porosity and pervious coefficient,in order to get the different factors that affect the performance of pervious concrete,which is the mix proportion of pervious concrete The design puts forward corresponding reference opinions.For the preparation process and working performance,through the compressive strength experiment,the influence of different preparation process on the performance of pervious concrete is studied.The compressive strength of concrete can be improved by both the method of cement bound stone feeding and the method of net slurry bound stone feeding.The quality of the remaining cement paste deposited is determined to be between 10-30 g by the workability test instrument,so that the mixture can achieve a better working performance.For the permeable concrete with design porosity of 15%and 20%,it is suggested to adopt the vibration forming method to vibrate for 25 s and20s respectively,while for the permeable concrete with design porosity of 25%,it is suggested to adopt the method of ramming forming with 12 times of ramming per layer.As for the mechanical and water permeability performance,through four indexes of compression resistance,bending resistance,porosity and water permeability coefficient,the influence of different factors on the performance of permeable concrete is studied.Under the same design porosity,with the increase of water cement ratio,the compressive strength and flexural strength decrease gradually.Under the same water cement ratio,the smaller the design porosity,the larger the compressive strength and flexural strength,and the smaller the permeability coefficient and measured porosity.The compressive strength of 5-10 mm coarse aggregate is higher.The compressive strength of pervious concrete can be improved by adding polypropylene fiber,sand and silica fume.The cement slurry formed by pebbles will gradually sink to the bottom during the forming process,which will affect the overall porosity and water permeability coefficient.Adding a small amount of polypropylene fiber can slightly improve the water permeability.Adding sand and silica fume will reduce the water permeability,and excessive sand will make the concrete lose the water permeability.In the aspect of durability,the durability of pervious concrete is studied through freeze-thaw cycle and sulfate immersion experiment.Adding polypropylene fiber and silica fume can improve the resistance of pervious concrete to freeze-thaw cycle.Adding silica fume can only reduce the mass loss of concrete after the freeze-thaw cycle,while adding polypropylene fiber can reduce the mass loss rate and maintain the integrity of concrete specimens.In the sulfate immersion test,the compressive strength of the three kinds of concrete increases first and then decreases.There are more expansive substances generated by chemical reaction after immersion for 40 days,which leads to greater expansion stress and strength failure in the concrete.In terms of plugging and recovery,the relevant laws of permeable concrete plugging are studied through plugging experiment and cleaning.The mixed particle size plugging agent can make the pore of concrete plug faster.The two particle size plugging agents,0.15-0.3mm and 0.3-0.6mm,are the main factors causing the pore plugging of permeable concrete.With the increase of water cement ratio,permeability coefficient decays faster,and permeable concrete with low water cement ratio is easier to clean and restore its permeability.The permeable concrete with high porosity has more internal connected pores,and it is easier to recover the pervious effect through cleaning after being blocked.