Production of binary fly ash and slag systems : investigation of key parameters in strength and microstructural development

• Main Author: Kieo, Douglas Yong Qiang
• Other Authors: Cise Unluer
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Civil engineering::Construction technology
• Online Access: http://hdl.handle.net/10356/78109
• Institution: Nanyang Technological University

Ground granulated blast-furnace slag (GGBS) is widely utilized as the main component in an alkali-activated cement. This study investigated the potential of fly ash to be incorporated and activated by reactive MgO alongside GGBS. The low hydration of MgO limits the subsequent carbonation and associated strength gain. Introduction of slightly elevated temperatures and accelerated carbonation conditions were made to improve the hydration, mechanical performance and microstructure development in reactive MgO-fly ash/slag concrete blends. The influence was examined through isothermal calorimetry, TGA, XRD and SEM. Implementation of an elevated temperature increased the rate and degree of hydration in the early stages. Mixes with 12% fly ash produced equivalent 28-day strengths compared to the control mix regardless of curing temperature. Accelerated carbonation after 28 days of ambient curing led to further improvements in mechanical performance and morphology of carbonates resulting in a strength gain of 64% of the control mix after 14 days. It is hence proposed that fly ash has the potential to be used as one of the materials in alkali-activated cement.