Physico-mechanical and microstructural properties of geopolymer binders synthesized with metakaolin and meta-halloysite as precursors

Abstract

The evolution of sustainable binders for various construction applications has resulted in the development of various geopolymer binders using various materials as aluminosilicate precursors. Geopolymer binders can be utilized as an alternative to Portland cement in the production of various materials such as mortar and concrete. In this study, geopolymer binders were synthesized using metakaolin (MK) and meta-halloysite (MH) as the aluminosilicate precursors and activated with an alkali solution having a silica modulus of 1.3 and 1.5. The resulting geopolymer binders were assessed in terms of the mechanical, permeability and durability properties. The findings from this study showed that the use of MH as the precursor resulted in better performance compared to when MK was used due to its higher reactivity and fineness. It was also found out that the use of a silica modulus of 1.5 is favourable to the hardened properties of the geopolymer binders. Geopolymer binders synthesized with MH and an activator with a silica modulus of 1.5 exhibited an increase in compressive and flexural strength of approximately 9 MPa and 1 MPa, respectively compared to when a silica modulus of 1.3 was used. Also, the corresponding porosity and water absorption is 14.5% and 10.9%, respectively lower.

Keywords

• Geopolymer
• Metakaolin, meta-halloysite
• Rheological behaviour
• Sustainability