Abstract
Significant drying shrinkage is one of the main limitations for the wider utilization of alkali-activated slag (AAS). Few previous works revealed that it is possible to reduce AAS drying shrinkage by the use of shrinkage-reducing admixtures (SRAs). However, these studies were mainly focused on SRA based on polypropylene glycol, while as it is shown in this paper, the behavior of SRA based on 2-methyl-2,4-pentanediol can be significantly different. While 0.25% and 0.50% had only a minor effect on the AAS properties, 1.0% of this SRA reduced the drying shrinkage of waterglass-activated slag mortar by more than 80%, but it greatly reduced early strengths simultaneously. This feature was further studied by isothermal calorimetry, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). Calorimetric experiments showed that 1% of SRA modified the second peak of the pre-induction period and delayed the maximum of the main hydration peak by several days, which corresponds well with observed strength development as well as with the MIP and SEM results. These observations proved the certain incompatibility of SRA with the studied AAS system, because the drying shrinkage reduction was induced by the strong retardation of hydration, resulting in a coarsening of the pore structure rather than the proper function of the SRA.
Highlights
Ordinary Portland clinker or cement (OPC)-based binders are probably the most common in concrete production
The aim of this paper is to investigate the effect of different types of shrinkage-reducing admixtures (SRAs) from those mentioned above on the shrinkage of activated slag (AAS), and on its other properties such as microstructural and strength development
This study investigated the effect of SRA based on 2-methy-2,4-pentanediol on the mechanical
Summary
Ordinary Portland clinker or cement (OPC)-based binders are probably the most common in concrete production. One ton of CO2 is released per one ton of cement produced [1]. It is necessary to search for some alternative binders such as calcium aluminate cements, calcium sulfoaluminate cements or supersulfated cements [2]. Another possible way is the formulation of alkali-activated binders, usually based on blast furnace slag (BFS), fly ash (FA) or metakaolin [3]. According to Duxson et al [4], geopolymers can provide approximately 80% reduction of CO2 emissions compared to OPC
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: 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.