Preparation Of SBS Latex And Its Applications In Micro-surfacing Mixtures

When micro-surfacing technology is used for asphalt pavement maintenance in cold areas, its anti-cracking performance at low temperature is particularly important, so modified asphalt emulsion must possess high properties of resistance to deformation at low temperature and elasticity recovery. Currently, SBR latex is developed successfully, while SBS is not, so styrene-butadiene rubber SBR is widely applied in modified emulsified asphalt used for micro-surfacing mixures. However, although the ductility at low temperature of SBR modified asphalt emulsion is better than SBS modified asphalt emulsion, its sticky toughness, resistance to deformation and deformation recovery is relatively weaker. Therefore, developing SBS latex has important significance in promoting the application micro-surfacing technology in the cold regions.Firstly, the swelling process of SBS and the rheological properties of SBS solution, the effect of time, temperature, concentration, shear rate and other factors on the SBS solution viscosity was analyzed and the temperature and time of heat preservation of SBS solution used for the subsequent emulsification was determined. Followed by preparation of SBS latex with good stability and water dispersibility, SBS solution acted as dispersed phase, emulsifier was YR and FR(mass ratio 3: 1), the emulsification method was the mechanical method(emulsifier in water), and the experiment design method was orthogonal design. Finally, the optimal formulas of star-type-SBS latex and line-type-SBS latex were obtained, their average particle diameter were 1.31μm and 1.16μm which matched the average particle diameter range of emulsified asphalt respectively.The modified asphalt emulsions were prepared with modifiers of line-type-SBS particles, SBR latex and homemade SBS latex, the experiments of penetration, softening point, ductility at 5℃ and elasticity recovery at 25℃ were carry out its evaporation residue to evaluate general performance, the sticky toughness at low temperature properties was evaluated by dynamic mechanical test and force ductility test, while this paper analyzed the temperature sensitivity in whole temperature domain asphalt pavement serviced at through viscositytemperature index, penetration index, the change rate of storage modulus and loss factors. Studies had shown that high temperature performance, low temperature resistance to deformation, temperature sensitivity and toughness of SBS modified asphalt emulsion residue were better than that of SBR modified group, and, road performance of star-type-SBS modified asphalt emulsion residue was better in SBS modified group overall.Micro-surfacing slurry mixtures were prepared with binder of different modified emulsified asphalt, its conventional performance was tested by wet track abrasion test and stability and resistance to compaction test, the crack-resistance was evaluated by splitting test, anti-fracture test and bending test. Experiments results showed that SBS modified emulsified asphalt micro-surfacing mixture had comprehensive advantages in all groups, while the road performance of SBS latex modified groups was weaker slightly than SBS particle modified group because of the existence of solvent. When the 60℃ curing time of specimen was prolonged to 36 h, the performances of SBS latex modified groups were a little better than that of SBS modified particle groups.