Optimization Design And Performance Research Of High And Early Strength Cement Emulsified Asphalt Grouting Material

Slab bottom unloading is a common disease of cement concrete pavement of airport.If measures are not taken in time,the bearing capacity of the pavement will decrease,which will seriously affect the takeoff and landing safety of aircraft.At present,the most common and effective maintenance and reinforcement measure was to use grouting materials to repair the hollow area.However,the grouting material has some problems,such as high brittleness,easy shrinkage,high price and serious pollution,which severely limit its application.In view of this situation,and considering the urgent demand for the early strength of grouting materials such as busy airport traffic and short maintenance window period,based on cement grouting materials,combined with cement early strength technology and the characteristics of emulsified asphalt,such as good flexibility,economic and environmental protection,this paper designed and studied a high early strength cement emulsified asphalt grouting material with good flexibility,high fluidity,economic and environmental protection.The main research contents and achievements are as follows:Firstly,by researching the adaptation of cementing material and emulsified asphalt,as well as the adaptaion of water reducing agent,the quality control indicator of emulsified asphalt and the choice of water reducing agent were defined.Considering the impact of the amount of raw materials on the working performance and mechanical properties,the critical preparation factors of high and early strength cement emulsified asphalt grouting material were decided by the control varying approach.Secondly,the working performance,mechanical properties,rheological properties,damping properties and durability of high and early strength cement emulsified asphalt grouting materials were systematically studied.The findings indicated that the high and early strength cement emulsified asphalt grouting material had good stability.With the increase of A/C,the air content increases and the strength reduces.The plastic viscosity and yield stress improved with the increase of A/C and retarder content,but decreased with the increase of water-binder ratio and water reducing agent content.The incorporation of emulsified asphalt could dramatically increase the impact resistance and damping properties of the grouting material and reduce the dry shrinkage rate.With the increase of emulsified asphalt content,the frost resistance of grouting material was weakened and the effect of sulfate erosion inhibition was strengthened.Thirdly,XRD,FTIR,SEM and TG tests were used to analyze the microscopic characteristics and hydration process of the high and early strength cement emulsified asphalt grouting material,so as to clarify its strength formation mechanism.The results showed that there was no chemical reaction between the cementitious material and emulsified asphalt,and they were just simple physical mixing.The addition of emulsified asphalt would delay the hydration process of cementitious material.As the age increases,a continuous asphalt film was formed and interwoven with hydration products of cementing materials,forming an organicinorganic composite network structure.The strength formation of high and early strength cement emulsified asphalt grouting material mainly included the hydration of cementitious material,emulsified asphalt demulsification,cement emulsified asphalt hardening and so on.Finally,the environmental benefits,economic benefits and actual performance of different grouting materials were analyzed and compared.It could be seen that the high and early strength cement emulsified asphalt grouting material had good comprehensive benefits and strong market competitiveness.