Rheological Behavior, Segregation, Microstructure, and Construction Quality of Cement-Emulsified Asphalt Mortar with Associative Thickener

Abstract

Cement-emulsified asphalt mortar (CAM) is a critically important engineering material for a slab ballastless track. Segregation, which results in a density difference between the upper and lower part of the hardened CAM, is the most important factor that affects construction quality in practice. With the aim of decreasing the segregation of CAM, a minute amount of associative thickener, in which the mass ratio of the thickener to emulsified asphalt was 0, 0.2, 0.4, 0.6, 0.8, and 1.0%, respectively, has been incorporated into CAM, and the effects were systematically studied in terms of rheological behavior, segregation, microstructure, and construction quality of CAM. The results showed that the segregation resistance of hardened CAM was dramatically improved by increasing the thickener, whereas the rheological behavior characterized by the workability and fluidity indexes was prone to worsen. Considering the technical and economic aspects, an optimum mass ratio of the associative thickener to emulsified asphalt of 0.4% was recommended. Simultaneously, the microstructure analysis indicated the proper amount of thickener takes an active role in the compacting matrix and in refining the pores of the hardened CAM. Furthermore, in the practical application, the thickener could increase both the surface hardness and homogeneity of CAM.