Feasibility Study on Fabrication of Geopolymer Bricks by Wasted Grinding Wheel at Room Temperature

Abstract

In this study, the feasibility of producing eco-friendly bricks by using geopolymer technology and a waste grinding wheel (WGW) from the grinding wheel industries was investigated. Nowadays, in order to meet industrial needs, for instance, in Taiwan, approximately 500,000 grinding wheels are used annually. That is, a large number of "waste" grinding wheels are produced. Furthermore, few studies have been conducted on the use of WGWs as raw materials in geopolymer applications. The use of geopolymer technology to form bricks can avoid the utilization of clay and cement and even prevent the use of a high-temperature process in kilns. Moreover, it can decrease CO 2 emission and energy consumption and thus, protect the environment. In this study, the following three major factors were considered: press-forming pressure (70 and 100 kgf/cm 2 ), NaOH molar concentration (2 and 4M), and the ratio of binder fineaggregate (1:3, 1:4, and 1:5). Under these conditions, the specimens were tested using the compressive strength test, water absorption test, microstructure analysis, a freezing-thawing test and toxicity characteristic leaching procedure test. The optimal formulation was composed of 1:4 binder fine-aggregate ratio, 4M NaOH concentration, and 100-kgf/cm 2 pressure. Furthermore, we used a WGW and achieved a compressive strength of 50.6 MPa after 28 days, which was greater than 32 MPa and conformed to the Grade A brick standard of National Standards of the Republic of China (13295). In conclusion, this brick fabrication method based on geopolymer technology was not only beneficial to the environment but also improved the efficiency of reutilizing WGW.