| The increasingly serious urban heat island effect has affected the urban living environment.The traditional asphalt pavement commonly used in urban municipal roads absorbs heat,which is not only one of the reasons for aggravating the urban heat island effect,but also brings a lot of high temperature of the asphalt pavement.Disease,this phenomenon is more obvious especially in places with high annual average temperature.The current research directions of cooling pavement mainly include porous drainage pavement,reflective pavement and heat collecting pavement,but each has many shortcomings.In order to solve these problems,it is urgent to develop a new type of cooling pavement material with low cost,mature manufacturing technology and obvious cooling effect,which can improve the durability of road use and at the same time play multiple effects of alleviating the local urban heat island effect.In this study,the development and optimization design scheme of semiflexible composite water-retaining asphalt pavement was summarized and extracted by comparing a variety of innovative renovation schemes for cooling and environment-friendly pavement.Research trials and results are as follows.1.Research and development of special water-retaining agent for composite waterretaining and cooling pavement.Through the comparison and selection of water-retaining agents,organic water-retaining agents were selected,and the swelling ratio and liquid storage rate of water-retaining materials were measured by mesh bag filtration method,and the waterretaining material SAP used in the study was determined;2.Research and development of special mortar for composite water-retaining and cooling pavement.By forming SAP mortar compressive and flexural specimens,the compressive and flexural strengths were tested,and the test results met the technical requirements of waterretaining pavement.The water absorption and water retention properties of SAP mortar were tested by immersion method and drying method,and the water absorption ratio and content of SAP mortar were finally determined;3.Research and development of high-viscosity modified asphalt for composite waterretaining and cooling pavement.Three kinds of high-viscosity modified asphalts were prepared by a laboratory high-speed shearing machine,the microphysical properties of the modified asphalts were investigated by FTIR and TEM,and special high-viscosity modified asphalts were tested using DSR’s Temperature Sweep and MSCR test methods The viscoelastic performance and high temperature performance test of SBS modified asphalt were found to be the best;4.Research and development of special asphalt mixture for composite water-retaining and cooling pavement.In this study,SFAC-13 was selected as the gradation of the composite water-retaining and cooling pavement matrix mixture,and the parameters such as the gradation range,the optimal oil-stone ratio,and the porosity of the matrix asphalt mixture were determined by the Marshall test.The water stability,skid resistance,crack resistance and cooling effect of the pavement material after grouting were evaluated.The test results found that the water stability met the design requirements,and the skid resistance was reduced but could be enhanced by later surface processing.The crack resistance will increase with the increase of the mortar mixing amount,and the cooling effect can reach a temperature difference of more than 10 ℃ with the ungrouted pavement,and the cooling effect is remarkable.In conclusion,this study summarizes a complete set of cooling pavement research and development methods,and successfully developed a cooling pavement material,which has good application and promotion value. |
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