Research On Water Stability Of Cement-rubber Modified Asphalt Mixture

Water damage of asphalt pavement caused by lack of water stability of asphaltmixture is a main type of early destruction. Measure of adding cement to asphaltmixture could enhance adhesion between asphalt and mineral aggregate and improvedwater stability of asphalt mixture. Rubber asphalt mixture has been widely used athome and abroad relying on its excellent performance, the characteristics ofenvironmental protection. Cement-rubber modified asphalt mixture has excellentperformance as a kind of new-typed pavement material. In this paper, water stability ofcement-rubber modified asphalt mixture was studied though laboratory experimentalstudy and finite element numerical simulation.At first, though studying preparation technology and pavement performance ofthe rubber powder/SBS composite modified asphalt,it is concluded the preparationtechnology and optimum material selection:mixing with16%20mesh rubberpowder,shearing for30minutes and shearing speed controlled in4000-5000r/min,and then mixing2%SBS, shearing for30minutes, agigating and developing for30minutes, temperature controlled in180~200℃in the entire process.Secondly, cement as ntistripping agent substituting mineral powder was added torubber modified asphalt mixture. It choosed the immersion scattering losstest,immersion rutting test and the whole-term evaluation method to evaluate waterstability of cement-rubber modified asphalt mixture with different cement dosage andmineral aggregate gradation. The test resurts showed that the cement can effectivelyimprove the rubber modified asphalt mixture water stability,and the effects can bemore significant in the more demanding of water environment.It recommend cementreplacement amountof cement-rubber modified asphalt mixture RAC-13was30%～60%.Thirdly, it regarded the asphalt pavement structure in water environment as theideal saturated fluid and solid porous media. Based on the porous media theory and theelastic multilayer mechanics theory, using finite element software ADINA simulate thesaturated asphalt pavement under vehicle loads,It comprehensively compared andanalysed the internal structure dynamic response of two kinds of asphalt pavementstructure with cement-rubber modified asphalt mixture and SBS modified asphalt mixture under vehicle loads. Calculation results showed that asphalt pavementstructure with cement-rubber modified asphalt mixture had lower pore pressure,lowervertical displacement, better resistance to deformation,little difference compared withasphalt pavement structure with SBS modified asphalt mixture.