Effect of emulsifier on cement hydration in cement asphalt mortar

Cement asphalt mortar (CA mortar) is a key material of non-ballasted track structure. In order to solve the problem that cement hardens slowly in CA mortar, the retarding effect of emulsifier on cement hydration was studied by measurement of cement setting time, hydration heat and X-ray diffraction analysis. Results show that emulsifier has significant retarding effect on cement hydration, which is relevant to the types of emulsifier and its dosages. The retarding effect increases with the increment of the mass ratio of emulsifier to cement. Significant differences in the setting time, cement hydration rate, hydration heat and the content of Ca(OH)₂ are detected utilizing different types of emulsifier. Emulsifier with excessive retarding effect on cement not only abort cement hydration in early age, but also cause a loss in the later hydration heat and content of cement hydrates. Therefore, suitable emulsifier with little retarding effect on cement hydration and its appropriate dosage are recommended when producing asphalt emulsion for CA mortar.