Preparation And Properties Of New Repair Materials For Cracks On Asphalt Concrete Pavement

The repair of asphalt concrete cracks is a great problem that needs to be resolved in the process of highway construction in our country. In order to develop a series of efficient and environmental friendly materials, two kinds of grouting materials were studied systematically, including nano-silica (Nano-SiO2) modified water-soluble epoxy itaconate (W-EI) and non-metallic powder of waste printed circuit boards (W-FR4) modified epoxy acrylate (EA).The synthesis of water-soluble epoxy itaconate was studied firstly. And the influences of monomer ratio, co-solvent selection and catalyst species on synthesizing effects were investigated. In addition, the effects of reaction temperature, amount of catalyst and polymerization inhibitor on reaction acid value were investigated by orthogonal test. After that, an optimal synthesis condition are shown as follows:monomer molar ratio of epoxy groups and itaconic acid is1:1.05, ethanol is selected as co-solvent, benzyl triethyl ammonium chloride is the catalyst, and the reaction temperature is110℃, reaction time is four hours, the amout of catalyst and polymerization inhibitor is1.8wt%and0.1wt%, respectively. Then the target product was confirmed by the analysis of Fourier transform infrared (FT-IR) spectra before carboxyl in the target product was neutralized to pH=7.5by means of methyl acrylate N, N-dimethylaminoethyl acrylate (DMAEMA).Based on the above researches, two kinds of chemical grouting materials were prepared in the paper, including nano-silica modified water-soluble epoxy itaconate composite grouting materials and W-FR4modified epoxy acrylate composite grouting materials. Before the modifications on W-EI and EA, conductivity method was used to monitor the hydrolysis degree of silane coupling agent KH-550(3-aminopropyl triethoxysilane). The hydrolysis reached to equilibrium after12minutes when the volume ratio of KH-550:ethanol:water is1:15:4. Based on the research of KH-550, the optimum surface treatment conditions of KH-550for nano-silica and W-FR4were determined. First, moistened nano-silica or W-FR4by0.1mol/L NaOH, added the hydrolyzed KH-550, the amount of which is4wt%determined by the modified one. Then processed with an ultrasonic for2hours under80℃, then filtered and dried nano-silica at90℃. For the nano-silica modified water-soluble epoxy itaconate composite grouting material, the effects of moisture content, nano-silica dosage, amount of trigger and promoter as well as environmental temperature on the performances of composite material was investigated. It has been found that moisture content could be adjusted according to the actual requirements of grouting viscosity (lower limit of viscosity is less than98mPa-s). The optimal added content of nano-silica is2wt%. Moreover, the amount of trigger and promoter depends on grouting time (a proper operable time ranges from minutes to hours). The cured composite material has good mechanical properties which resulted in a tensile splitting strength of3.28MPa, a force ductility of35mm, and a penetration number of12mm. While for the W-FR4modified epoxy acrylate composite grouting materials, the effects of W-FR4particle size, the amount of W-FR4and diluents on mechanical properties of the composite grouting materials were studied. The results show that the W-FR4particle size is from0.075to0.106mm, and the amount of them is15wt%, the amount of diluents could be adjusted according to the grouting viscosity in actual grouting requirements (lower limit of viscosity is less than20.53mPa-s). Furthermore, the superficial treatment of W-FR4has little influence on the mechanical properties of the cured composite grouting materials which results in a compressive strength of87.28MPa and a tensile splitting strength of6.88MPa.As we know, the composite grouting materials of nano-silica modified water-soluble epoxy itaconate combines the superior properties (high strength, strong bond and low viscosity) of general grouting material. And for the W-FR4modified epoxy acrylate composite grouting materials, the W-FR4is recycled effectively, and the EA is also strengthened and toughed. Therefore, both of the two kinds of grouting materials can be used to repair cracks of asphalt concrete pavement.