Development of geopolymer-based materials from coal bottom ash and rice husk ash with sodium silicate solutions

• Main Authors: Nguyen, Hoc Thang, Pham, Trung Kien, Promentilla, Michael Angelo B.
• Format: text
• Published: Animo Repository 2018
• Subjects: Inorganic polymers; Coal ash; Rice hulls; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/3840; https://animorepository.dlsu.edu.ph/context/faculty_research/article/4842/type/native/viewcontent/978_981_10_6713_6_40.html
• Institution: De La Salle University

The coal bottom ash is a solid waste generated from coal-fired thermal power plants that contains high alumino-silicates resources. Rice husk ash was burned from rice husk which has over 80% silica in its chemical composition. The alumino silicates resources in these materials have high reactivity in various conditions such as that of alkaline reactions and thermal reactions. Therefore, both coal bottom ash (CBA) and rice husk ash (RHA) are promising raw materials for synthesizing alkali activated materials through geopolymerization. This study focuses on utilization of CBA and RHA to produce geopolymer – based materials using sodium silicate solution as an alkali activator. This is one of the potential solutions that would not only manage the coal bottom ash but also an avenue to utilize the waste to produce green materials. The production of geopolymer-based materials results to lower energy consumption, minimal CO2 emissions and lower production cost as it valorizes industrial waste. The CBA and RHA were mixed with sodium silicate solution to obtain the geopolymeric pastes. The pastes were molded in 5-cm cube molds according to ASTM C109/C109 M 99, and then cured at room temperature for 28 days. The 28-day geopolymer specimens were tested for engineering properties such as compressive strength (MPa), volumetric weight (kg/m3), water absorption (kg/m3) and thermal conductivity (W/m.K). Microstructure of the best geopolymer sample was characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). © Springer Nature Singapore Pte Ltd. 2018.