Performance Analysis Of Pervious Concrete And Design Of Precast Pavement Slab

Pervious concrete is a porous concrete made of cement,aggregate of specific gradation,reinforcer and water.It can also be regarded as a structure formed by the bonding of cementitious materials between aggregates.Compared with ordinary concrete,pervious concrete has better water permeability because there are more connected pores inside the structure.Its application in urban roads can not only alleviate the reflective water on rainy days,absorb noise and dust,but also reduce the urban "heat island effect".At present,the construction of pervious concrete pavement usually adopts the on-site construction method,which causes pollution to the environment,is easy to produce noise and is more affected by construction conditions.Precast pervious concrete pavement slab is a kind of pavement slab which is delivered to the site after the production is completed in the assembled factory.It has the advantages of high construction efficiency,low pollution to the environment and good quality.This topic complies with the requirements of green development,taking pervious concrete as a pavement paving material,on the one hand,the design of pervious concrete mix ratio,through a single factor test to study the influence of various factors on the performance of pervious concrete pavement surface layer concrete material,and finally optimize the mix ratio.Reference,on the other hand,the existing ordinary concrete pavement and the permeable concrete pavement specification and documents,to the overall design of precast permeable concrete pavement,reduce the environmental impact from the site construction already,also make the waterproof concrete is better applied to urban road,improve pavement seepage velocity,acoustic noise reduction and alleviate the effect of underground water level.The main research contents and achievements of this topic are as follows:（1）Research on raw material properties.To test the sand and stone quality required by the test.The apparent density of diabase with particle size of 10-20 mm is the largest,and that of bluestone with particle size of 5-10 mm is the least.Diabase with particle size of 10-20 mm has the largest compact density and bulk density,while dolomite with particle size of 5-10 mm has the largest compact density and bulk density of diabase.Bluestone with a particle size of5-10 mm has the largest mud content.Basalt with particle size of 5-10 mm has the largest needle-sheet content.Dolomite with particle size of 5-10 mm has the largest crushing value.（2）Study on the mix ratio of pervious concrete.According to the calculation method of pervious concrete mix ratio,the ratio is obtained,and the test is carried out first.The compressive strength and permeability coefficient of the tested pervious concrete are tested for 7d,and the final mix ratio is determined after the ratio is adjusted according to the test results.（3）Study on performance of pervious concrete.The concrete under pervious concrete pavement slab was prepared and studied by 21 groups of tests with 9 single factor variables.Through 6 groups of experiments,the preparation and study of the concrete of pervious concrete pavement slab with 2 single factor variables were carried out.Tested performance and analyzed results.The effects of aggregate particle size,design porosity,water-binder ratio,silica fume content and other factors on the performance of pervious concrete were comprehensively analyzed.Among them,the aggregate size,design porosity and silica fume content are negatively correlated with the compressive strength and flexural strength of pervious concrete,while the special type free reinforcer and water-binder ratio are positively correlated with the compressive strength of pervious concrete.The permeability coefficient of pervious concrete is negatively correlated with aggregate particle size,special type free reinforcer and water-binder ratio.In addition,after 25 freezing-thawing cycle tests,all the indexes of concrete test blocks under permeable pavement slabs meet the requirements of frost resistance.（4）Design and research of prefabricated permeable pavement slab.Combined with the research status of prefabricated pervious concrete pavement slab at home and abroad in recent years,taking Taiyuan area as an example,the Code for Design of Highway Cement Concrete Pavement（JTGD40-2011）and the preliminary test results are taken as the calculation basis and guidance,and the relevant design requirements of pervious concrete are referred to.Through calculation and verification,the structure and thickness of each layer of pervious concrete meet the requirements,which provides a basis for industrial application of enterprises.