Research On Shrinkage Performance Of Cement Emulsified Asphalt Mixture

The shrinkage performance of cement emulsified asphalt mixture is mainly caused by itsconstituent materials and the temperature of the external environment. Especially, cement,emulsified asphalt and the reaction with aggregate, has a direct influence on the performanceof the mixture.To research the changes of the shrinkage performance of mixture under differentinfluence factors, the change rule of contraction coefficient of mixture was measured duringthe drying shrinkage and temperature shrinkage test, by changing the content of cement,emulsified asphalt and aggregate gradation type; at the same time, combing with the opticalmicroscope, scanning electron microscopy(SEM), and X-ray diffraction(XRD), themicrostructure of cement emulsified asphalt mortar and its existing state in the mixture hasbeen observed, and analyzed the influence mechanism.The experiment data and microcosmic figures show that: as the growth of the age,shrinkage rate of the mixture decreased as the dosage of cement, the activity was increasedwith dosage of emulsified asphalt; mineral powder plays the role of filling. A large number ofwater of crystallization of compound which was produced during the hydration intertwinedwith asphalt, and the density of the mixture structure has increase. To research the temperaturefactor, in different temperature range, the contraction coefficient of mixture decreased; withthe rigid materials cement, the flexibility of the mixture has diminished, the temperaturesensitivity has reduced. The viscosity is characterization of thermal properties of the asphaltmaterial, is also used to measure the stiffness modulus of the mixture, which directly affectsthe temperature stress and strain of mixture, and determines the cracking resistance of themixture. With AC-5, AC-10, AC-13mineral aggregate gradation, comparative tests has beendid. The shrinkage performance of the coarse gradation mixture with more coarse aggregateperforms well. And the fine gradation mixture with more fine aggregate has high compactness,which was bad for the release of the temperature stress and temperature shrinkage cracking.Finally, according to the reasons of the shrinkage of cement emulsified asphalt mixture,the shrinking model of the mixture has been put forward. The contraction coefficient has beenverified with the material property index. The result calculated by the model is close to theexperimental data.