Study On The Design System And Evaluation Index Of Fog Seal With Sand On Dense Gradation Asphalt Pavement

Fog seal with sand material is a new preventive maintenance technology based on fog seal.The technology has been widely used abroad,but domestic research is still in its infancy.There is no systematic specification and means for the evaluation and design of this material.Based on the study of existing materials at home and abroad,this paper puts forward a complete set of road performance evaluation indexes and design indexes.On this basis,Wearing Fog Seal with Sand(WFSS)product is proposed.The guidelines for the design,evaluation and construction of fog seal with sand,which is suitable for domestic requirements are formed to provide a basis for the promotion of fog seal with sand materialsBased on the analysis of the function and principle of the fog seal with sand,the definition of the preventive maintenance material and the requirement of the road condition are given.The laboratory tests of MasterSeal and BEST-MBR show that the MasterSeal material has better road performance and BEST-MBR has better construction performance.Different products should be selected according to different situations.A set of evaluation indexes and testing methods were proposed by evaluating the properties of materials.Including water sealing performance,skid resistance performance,wearing resistance,improvement of aging asphalt performance,traffic opening time,seepage performance and construction performance.In order to achieve the evaluation of materials,this study uses a number of self-developed equipment,including Tinfoil-Salt crack-making equipment,extreme wearing meter,combination set of traffic opening time,seepage groove,slump flow meter,etc.In order to realize the optimization of material design,this study proposes two design indexes for emulsion and mixture.Suspension capacity of emulsion,storage stability of emulsion,volume shrinkage of mixture and dynamic suspension stability of mixture.The emulsified asphalt,MasterSeal and BEST-MBR were used to test the design indexes of emulsion and mixture.The results show that the four design indexes can guide the material design.Among them,the suspension capacity of emulsion and the dynamic suspended capacity of mixture can be designed compositely.Volume shrinkage is a qualified index,not used to evaluate the quality of materials.Self-developed equipment,dynamic suspension agitator is used for dynamic suspension testOn this basis,a kind of WFSS type fog seal with sand material is proposed,and the design index and evaluation index test are carried out.The range of water content and the amount of dynamic suspended sand are given by design index.The formulation range of the material was optimized according to the construction performance.The road performance of the optimized material was evaluated,and the reasonable formula range and the optimal water content were given.At this time,WFSS has good wear resistance and construction performance,and can restore aged asphalt to a certain extent.There is no seepage on the pavement after spreading.The skid resistance meets the requirements of road.The result of economic benefit analysis shows that WFSS has lower cost,and it can save a lot of cost compared with the micro-surface and milling and paving.It has significant economic benefit.Improving the appearance of urban roads,serving a harmonious society,WFSS has good social benefit.