Formation of C-S-H in calcium hydroxide–blast furnace slag–quartz–water system in autoclaving conditions

In masonry, the most commonly used materials are concrete blocks or burnt clay brick. Owing to energy costs, there is a need to explore alternative raw materials and energy-efficient technologies for making building materials. This paper deals with the incorporation of blast furnace granulated slag in sand–lime materials as a replacement for hydrated lime during autoclaving conditions. The slag grain-size grinding and the heat treatment in saturated vapour pressure autoclave conditions were investigated to study the compressive strength behaviour of the new material. This substitution induces a decrease in compressive strength. The reaction products consist mainly of 11 nm tobermorite and xonotlite. The X-ray diffractions of these phases are difficult to see. The slag seems more reactive with lime than quartz. Observations with the scanning electron microscope allow better appreciation of these crystallites. With its composition and amorphous structure, the granulated slag does not release new distinct ph...