Abstract
The utilisation of near-neutral salts as activators to produce alkali-activated slag cements offers several technical advantages, including reduced alkalinity of the binders, minimising the risk associated with handling of highly alkaline materials, and better workability of the fresh paste compared to that of sodium silicate-activated slag cements. Despite these evident advantages, the delayed setting and slow early-age mechanical strength development of these cements have limited their adoption and commercialisation. Recent studies have demonstrated that these limitations can be overcome by selecting slags with chemistry which is more prone to react with near-neutral salts, or by adding mineral additives. A brief overview of the most recent advances in alkali-activation of slags using either sodium carbonate or sodium sulfate as activators is reported, highlighting the role of material design parameters in the kinetics of reaction and phase evolution of these cements, as well as the perspectives for research and development of these materials.
Highlights
Alkali-activated cements are materials produced via the chemical reaction of a poorly crystalline aluminosilicate powder, and a highly alkaline solution, to form a hardened solid
Alkali activated cements are usually produced from industrial wastes or byproducts such as blast furnace slag derived from the ironmaking industry, fly ashes from the coal combustion process, among others [2], and are commercialised in several places around the world [3]
Significant advances have been made over the past decade in understanding alkali-activated slag materials at micro- and macroscopic scales, as discussed in recent reviews [7, 8], for those materials produced with sodium silicate solutions as alkali-activator
Summary
Alkali-activated cements are materials produced via the chemical reaction of a poorly crystalline aluminosilicate powder, and a highly alkaline solution, to form a hardened solid. Some of the technical challenges associated with the use of near-neutral salt activators have been overcome by incorporating into the activated slag cements minor fractions of clinker or Ca(OH)2 [26], limestone [27], or utilising blended activating solutions of sodium carbonate or sulfates with sodium hydroxide or silicate solutions [28], or adopting high temperature curing [1] All these different approaches make the material harden; in order to move towards a more standardised way of developing alkali-activated slag binders, it is required to consider the role of the chemical and mineralogical characteristics of slags from different sources, to select the most suitable activator for a given slag
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
