Optimization design of asphalt emulsion with rejuvenator towards a uniform distribution inside the damaged porous asphalt mixture for a better ravelling resistance

Porous asphalt (PA) pavements usually meet the ravelling disease after opening to traffic for several years. Spraying surface treatment (ST) emulsion to PA pavement is a feasible preventive maintenance technology to alleviate this problem. However, the void clogging, nonuniform distribution and low diffusion efficiency of ST residue might hinder its widespread application. Therefore, this study aims to optimize the ST emulsion formula to improve the ravelling resistance of damaged PA. Usages of adding rejuvenators into ST emulsions were discussed. The orthogonal design method was used to determine the appropriate parameter values for preparing rejuvenator emulsions. The viscosity, contact angle and water boiling tests were then conducted to determine the optimal dosage of rejuvenator emulsion within ST emulsion. Cantabro abrasion test was performed to verify the ravelling resistance of damaged PA mixtures treated with optimized ST. Results showed that a stable and homogeneous rejuvenator emulsion could be produced by precisely controlling the PH value, emulsified temperature and emulsifier dosage. Adding rejuvenator emulsions to ST emulsions significantly improved the wettability. The optimal dosages of aromatic oil and tall oil emulsions are 10 % and 5 % by mass of ST emulsions. Optimized ST containing rejuvenator emulsions showed better ravelling resistances than pure asphalt emulsion.