Strength and microstructure evaluation of recycled glass-fly ash geopolymer as low-carbon masonry units. (1st July 2016)

• Record Type: Journal Article
• Authors: Arulrajah, Arul; Kua, Teck-Ang; Horpibulsuk, Suksun; Phetchuay, Chayakrit; Suksiripattanapong, Cherdsak; Du, Yan-Jun
• Is Part Of: Construction & building materials. Volume 114(2016)
• Page Start: 400
• Page End: 406
• Publication Date: 2016-07-01
• Subjects: Glass -- Fly ash -- Geopolymer -- Masonry -- Recycling; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2016.03.123
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Geopolymerization of recycled glass and flyash to produce a recycled masonry unit. Evaluation of unconfined compressive strength with respect to different chemical compositions and curing conditions. Microstructure analysis with scanning electron microscope. Abstract: The objective of this research was to evaluate the strength development of industrial by-products, namely Recycled Glass (RG) and Fly Ash (FA) in the manufacture of low carbon masonry units. A low carbon concept for manufacturing masonry units using RG-FA geopolymers was explored by applying low curing temperature of 50 °C and a low curing period of just 3–7 days. RG, being rich in silica was used as a filler material. FA, being a silica and alumina rich industrial by-product was used as a precursor in the RG-FA geopolymers. A liquid alkaline activator (L) comprising of a sodium hydroxide-sodium silicate solution was used for the alkali activation of 30% content of FA in the RG-FA blend. Factors found to affect strength development of the RG-FA geopolymers were: (1) the ratio of sodium hydroxide and sodium silicate in the liquid activator, (2) application of a low curing temperature of only 50 °C, (3) short curing periods of just 7 days and (4) the L/FA ratios. A geopolymer composed of a 70% Na2 SiO3 :30% NaOH ratio with a L/FA ratio of 0.625 was found to be the most efficient combination to provide the required unconfined compression strengths for manufacturing masonry. The usage of RG-FA geopolymers as low carbon masonry units was found to be viable using a low curing period of just 7 days and a curing temperature of just 50 °C. The RG-FA geopolymers had sufficient compressive strength be used as structural masonry units and needed only a low amount of heat treatment to achieve the minimum strength requirement. Optimally, 30% of FA was found to be sufficient for geopolymerization to occur for this novel low carbon RG-FA masonry units. Furthermore, the core materials needed to produce RG-FA masonry units were industrial by-products, the sustainable usage of which would contribute significantly to efficient waste management, through the production of aesthetically pleasing masonry units.