High performance C-A-S-H seeds and sulfate-rich lithium slag by nano-mechanochemical method on cement hydration: Microstructure and mechanical performance

Abstract

This study proposed a novel method for acquiring inexpensive and efficient seeds of calcium alumina silicate hydrate (C-A-S-H). Specifically, C-A-S-H seeds (CASH) (i.e., around 373 nm) with two morphologies (i.e., foil-like and fiber-like) were observed by using fly ash and carbide slag after 4 h nano-milling and 3 days wet grinding. Moreover, the utilization of sulfate-rich lithium slag (LS) in cementitious materials was rarely reported until now. In this study, the combination effect of nano-sized LS and CASH on cement hydration was investigated systematically. It was discovered that the compressive strength of cement mortar with the combined use of very low dosage (i.e., 0.1 %) CASH and 2.0 % nano-sized LS shows around 20 MPa at the age of 18 h, which exceeds two times that of plain cement mortar and still increased by 16 % at the age of 28 days. The superior combined accelerating effect on cement hydration using the above CASH and nano-sized LS provides a choice for the requirement of high early-strength concrete and the highly-added value utilization of fly ash and lithium slag.