The Applied Research On Water-holding Pavement In The Sponge City Squares

Sponge city refers to the city can be like a sponge,as a result of the disaster caused by the storm has a good buffer effect.when it rains,they can suck and store water.When needed,they can release the stored water and use.The general office of the State Council proposed guidance for the sponge city,to 2020,taking advantage of the Infiltration,retention,storage,Purification,using,discharge and other measures can consume and use the 70% of the rainfall.Obviously,the construction of sponge city is very important.The urban pavement as a direct acceptance of rainfall,the area accounted for 8%~15% of the land area to city construction,if making the road with the function of water-sucking,water-storing and water-releasing,it will have very important significance to the construction of the sponge city.In the past,the research on the water-holding pavement is based on the carrier of porous matrix asphalt mixture,filling the water-holding mortar.the water retention rate can reach about 20%.The porosity of the matrix asphalt limits its water retention effect.Therefore,this paper is aiming at the limitation of water retention of water-holding semi flexible pavement,combined with the characteristics of city square and the sidewalk pavement,a dedicated to the city square and the sidewalk pavement model water-holding pavement structure is proposed.This kind of pavement structure not only inherits the advantages of rigidity and soften,but also adopts the water-holding layer,which makes the overall water-holding capacity of the pavement improved.The above layer of pavement structure is made of water-holding and semi-flexible pavement,and the bottom layer is made of water-holding cement concrete,and the water-holding structure makes the overall water holding capacity of the pavement increase.Based on the research at home and abroad,according to the water-holding semi flexible pavement and the composite of cement concrete and asphalt concrete pavement,a new type of pavement structure is proposed.The layers from top to bottom is mainly divided into: water-holding semi flexible pavement upper layer and water-holding cement concrete bottom layer,graded macadam base,Soil compaction.The water-holding bfunction is mainly reflected in the surface layer.This paper focuses on the cooling performance of the water retentive pavement,pavement structure and material selection,water retention mechanism,water retention material mixture of cement slurry,optimization design method of water retention and water retention of cement concrete pavement.Firstly,summarizing the previous research results,preliminary determinating the water-holding cement raw material as well as the initial ratio range,and then through the orthogonal test to optimize the mix of raw materials,and analyzed the influence of admixture of water-holding cement mortar,determined the water-holding cement mortar satisfy the basic mechanical,fluxility and water-holding property,water retention of cement mortar.Secondly,considering the results of this study are mainly used in the city square and sidewalk pavement,the strength requirement is not high,therefore,the bottom layer is mainly using the water retention rate as the main control index.In order to improve the water retention rate,cement concrete aggregate is mainly using the porous shale ceramsite.Finally,through the experimental,researching on the cooling temperature of the whole assembly of the pavement,and comparing with the ordinary cement concrete,porous asphalt concrete,and double times sucking overall composition.On the base of the experimental research,the water-holding performance is remarkable,the cooling effect is also very obvious.it can be widely used in the city squares and sidewalk pavement,if widely used in urban and sidewalk pavement can not only relieve the pressure of draining off water,but also alleviate the urban heat island effect.It has a certain promotion value and engineering practical significance.