Abstract: CA mortar is a viscoelastic material and is used in slab track as a stress absorbing layer.The mechanical property of CA mortar exhibited a strong time-dependence due to the pervasive presence of asphalt in its structure.The paper explored the variation in compressive strength of CA mortar under different loading rate,and also investigated the effect of ratio between asphalt emulsion and cement,the fineness modulus (FM) of sand,and the incorporation of silica fume (SF) and crumb rubber (CR) on the time related behavior of CA mortar.Resultsindicated that the compressive strength of CA mortar was increased with a higher loading rate,and the upward trend was mitigated when less asphalt was present.A decrease in FM of sand and the incorporation of SF and CR contributed to weakening the time dependence of compressive strength on the loading rate,but a smaller FM of sand would result in exorbitant loss of fluidity of CA mortar.A hypothesized model of asphalt distribution in CA mortar was put forward to shed some light on the mechanism of time dependence of its mechanical property.