Preparation And Properties Of Emulsified Asphalt Cement Composites

China’s road traffic industry is developing rapidly,and the problem of road maintenance is imminent.Emulsified asphalt has become an important material in road maintenance and repair technology with the advantages of energy saving,normal temperature construction.Among them,asphalt emulsifier is the key to the preparation of emulsified asphalt.Therefore,under different oil-to-water ratios(60:40 and 70:30),four anionic emulsifiers(sodium dodecyl benzene sulfonate,sodium dodecyl sulfate,sodium oleate and sodium stearate)were selected,three kinds of cationic emulsifiers(cetyl trimethyl ammonium bromide,dodecyl trimethyl ammonium chloride and cetyl trimethyl ammonium chloride).By adjusting the amount of emulsifier to prepare emulsified asphalt emulsion,by testing the penetration of the asphalt emulsion evaporation residue,softening point,ductility and other indicators,select the anionic emulsifier and cationic emulsifier with excellent performance.Through the test of condensation time and mechanical properties,combined with scanning electron microscopy,X-ray diffraction and Fourier transform infrared spectroscopy,the influence of anion emulsified bitumen on the mechanical properties of CA mortar was explored,the main findings reached are as follows:(1)Under the oil-water ratio of 60:40,the needle penetration,softening point and ductility of the evaporation residue of emulsified bitumen are better than those of the oilwater ratio of 70:30 performance.Under the condition of oil-water ratio of 60:40,sodium dodecyl benzene sulfonate,sodium dodecyl sulfate,sodium stearate,cetyl trimethyl ammonium bromide,dodecyl trimethyl ammonium chloride and cetyl trimethyl ammonium chloride as emulsifiers,when the amount of blending increases from 1.4% to2.0%,the penetration of emulsified bitumen is increased first and then decreased,while the penetration of sodium oleate emulsifier gradually decreases.Due to the difference in emulsifier type and performance,when the emulsifying bitumen softening point increases from 1.40% to 2.0% with the amount of emulsifier,there will be a significant softening point inflection point.The ductility varies in length.Among them,when the dosage of sodium dodecyl sulfate anionic emulsifier is 1.6%,it has better performance than the other three anionic emulsifiers.When the cetyl trimethyl ammonium bromide cationic emulsifier is mixed at 1.80%,it has better performance than the other two cationic emulsifiers.(2)Under of oil-water ratio of 60:40,with the increase of emulsified asphalt mixing,the coagulation time of the slurry is prolonged.When the amount of emulsified bitumen is 50%,the initial coagulation and final coagulation time of emulsified bitumencementitious materials is the longest,of which the initial coagulation time of the anionic emulsifier mixed with sodium dodecyl l sulfate is 362 min,and the final coagulation time is 407min;the initial coagulation time of the cetyl trimethyl ammonium bromide cationic emulsifier is 362 min and the final coagulation time is 395 min.(3)Under the oil-water ratio of 60:40,at the age of 28 d,when the amount of sodium dodecyl sulfate is 10%,the mechanical properties of the specimen are optimal,and its flexural strength is 15.4MPa and compressive strength is 67.2MPa;when the cetyl trimethyl ammonium bromide is 10%,the mechanical properties of the specimen are optimal,with a flexural strength of 13.8MPa and a compressive strength of 61.8MPa.As the proportion of emulsified bitumen/cement increases,the pores of the internal structure of the slurry increase,and the mechanical properties of the specimen decrease.The emulsified asphalt with sodium dodecyl sulfate added has better bending resistance at the same temperature,and the bending strength decreases as the temperature increases.