Basic properties of non-sintering cement using phosphogypsum and waste lime as activator

Abstract

This study aims to manufacture non-sintering cement (NSC) by adding phosphogypsum (PG) and waste lime (WL) to granulated blast-furnace slag (GBFS) as sulfate and alkali activators. The non-sintering cement’s basic physical and chemical properties are also investigated by evaluating the compressive strength, and the hydrate of NSC. As a result, although the compressive strength is fairly similar to that of ordinary Portland cement (OPC) in the early curing age, it reaches a higher level in the later age than that of OPC due to the continuous reaction of slag and PG. Results obtained from analysis of the hydrate have shown that the glassy films of GBFS are destroyed by the activation of alkali and sulfate, ions eluted from the inside of GBFS react with PG and produce ettringite, and consequently the remaining component in GBFS slowly produced C–S–H(I) gel. Here, PG is considered not only to play the role of simple activator, but also to work as a binder reacting with GBFS.