Factors influencing the structure build-up of fresh cement asphalt emulsion paste

Abstract

Fresh cement asphalt emulsion mortar (CA mortar) is required to be highly flowable for grouting when it is employed in slab track structure. Segregation and bleeding easily occur after placement. In essence, it is because fresh CA paste has a low rate of structure build-up. However, limited information is reported about the thixotropy of CA paste. A thixotropy model based on structure parameter, which is deduced from constant shear rate test, is proposed to study the structure build-up of CA paste. In the model, the initial structure parameter and the rate of structure build-up are used to describe the evolution law of the structure parameter with resting time, which can be employed to quantitatively evaluate the structure build-up process of CA paste. The thixotropy model is used to study the influence of every constituent on the structural build-up process of CA paste. Results show that asphalt emulsion and superplasticizer dosage are two main factors influencing the structure build-up of CA paste, but water-to-cement ratio and viscosity-modified agent dosage have little effect on the structure build-up of CA paste.