Compressive strength and microstructural properties of spent coffee grounds-bagasse ash based geopolymers with slag supplements. (20th September 2017)

• Record Type: Journal Article
• Authors: Arulrajah, Arul; Kua, Teck-Ang; Suksiripattanapong, Cherdsak; Horpibulsuk, Suksun; Shen, Jack Shuilong
• Is Part Of: Journal of cleaner production. Volume 162(2017)
• Page Start: 1491
• Page End: 1501
• Publication Date: 2017-09-20
• Subjects: Coffee grounds -- Bagasse ash -- Geopolymer -- Recycling; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2017.06.171
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Spent coffee grounds (CG) is a beverage waste derived from the drinking coffee. Bagasse ash (BA) is the residue obtained from the burning of sugarcane for electricity. This paper aims to create and assess the feasibility of a recycled construction material formed by binding CG with a BA geopolymer, through the alkaline activation of BA using sodium hydroxide (NaOH). Slag (S), an industrial waste, was used to supplement CG+BA mixes. The mass ratios of the granular solids used were 70CG:30BA, 70CG:10BA:20S, 70CG:20BA:10S, and 70CG:30S. Strength development was assessed using the Unconfined Compressive Strength (UCS) test. Microstructural analyses were done by scanning electron microscopy (SEM). Specimens were cured at 21 °C and 50 °C, for durations of 7, 28, 60, and 90 days. This study found that 50 °C curing was necessary to adequately strengthen the mixes and inhibit organic content growth at long curing durations. Conclusively, this CG+BA geopolymer requires extended curing periods to achieve high UCS. The maximum recorded UCS in this study was 1482 kPa, achieved by 70CG:20BA:10S cured at 50 °C for 90 days. 70CG:20BA:10S provided the optimum aluminosilicate-to-alkali ratio for geopolymerization. Under optimum curing conditions, the geopolymer mixes were found to meet the minimum specified UCS requirements for subgrade materials in various countries. Highlights: A recycled construction material from beverage and agricultural wastes was developed. Spent Coffee Grounds was bound with a Bagasse Ash geopolymer. Slag provided supplementary strength for Spent Coffee Grounds. Long-term strength and microstructural development of geopolymers were discussed.