Preparation of Ca/Al-Layered Double Hydroxide and the influence of their structure on early strength of cement

•The Ca/Al-LDH was prepared by coprecipitation method.•The structure of Ca/Al-LDH affected the mechanical properties of cement slurry.•The structure of Ca/Al-LDH determined its mode of promoting cement hydration. Ca/Al-Layered Double Hydroxide (Ca/Al-LDH), was a kind of important anionic clays with broad applications owing to its properties of exchangeable anion and adjustable particle size. In this study, Ca/Al-LDH had been successfully prepared by co-precipitation method, and it was found that the particle size, crystallinity and morphology of Ca/Al-LDH could be tuned via changing ethanol/water ratio of solution. More interestingly, with the increase of the Ca/Al-LDH’s dosage, the different crystal structure of Ca/Al-LDH had promoting effect on the development of the early strength of the cement slurries, however, the change trend of the strength growth rate of various kinds of cement slurries were quite different. Meanwhile, experimental results disclosed that the crystallinity and particle size of Ca/Al-LDH determined its interaction with cement hydration particles. That was likely to lead to a change in tricalcium silicate (C3S) and tricalcium aluminate (C3A) hydration process of accelerating or retarding under the different Ca/Al-LDH content, thus enabling the early strength development of slurry to exhibit different trends. And this finding could provide further interpretation for the effect of hydrotalcite-like materials on cement hydration process and offer a theoretical exploration for its practical application in the future.