A geopolymer has been reckoned as a rising technology with huge potential for application across the globe. Dolomite refers to a material that can be used raw in producing geopolymers. Nevertheless, dolomite has slow strength development due to its low reactivity as a geopolymer. In this study, dolomite/fly ash (DFA) geopolymer composites were produced with dolomite, fly ash, sodium hydroxide, and liquid sodium silicate. A compression test was carried out on DFA geopolymers to determine the strength of the composite, while a synchrotron Micro-Xray Fluorescence (Micro-XRF) test was performed to assess the elemental distribution in the geopolymer composite. The temperature applied in this study generated promising properties of DFA geopolymers, especially in strength, which displayed increments up to 74.48 MPa as the optimum value. Heat seemed to enhance the strength development of DFA geopolymer composites. The elemental distribution analysis revealed exceptional outcomes for the composites, particularly exposure up to 400 °C, which signified the homogeneity of the DFA composites. Temperatures exceeding 400 °C accelerated the strength development, thus increasing the strength of the DFA composites. This appears to be unique because the strength of ordinary Portland Cement (OPC) and other geopolymers composed of other raw materials is typically either maintained or decreases due to increased heat.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

Rice husk ash (RHA), a byproduct of the rice industry, is the primary source of amorphous silica for producing sodium silicate solutions to replace standard commercial sodium silicate in geopolymer mixture design. The effect of various concentrations of NaOH used as an activator to produce epoxy-geopolymer cement was studied. Three initial concentrations of NaOH were used (8, 10, and 12M) to examine the optimum dissolution and formation of silica oligomers that can function as the activator during the geopolymerization. The result indicated the increase of NaOH concentration raises the silica yield strength. The silica yield found was 65.84%, 70.53% and 72.06% on NaOH use of 8, 10, 12 M, respectively. IR-spectra results showed silica functional groups and the sodium silicate were successfully synthesized. The IR spectra indicated the appearance of hydroxyl bonds, which strengthen the geopolymer matrix. SEM results showed the C-S-H and N-A-S-H bonds in the geopolymer. With 10M NaOH, the compressive strength of the geopolymer cement paste was optimal at 27.53 MPa. Thus, Rice husk ash (RHA) is feasible to be used as an activator in high calcium fly ash-based epoxy geopolymer cement.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

Geopolymer is cementitious binder that has enormous potential to become an alternative to ordinary Portland cement (OPC). Geopolymer composites have the potential to substantially curb the carbon dioxide (CO₂) emissions. Kaolin, metakaolin, slag and fly ash have been used as the prime materials for forming geopolymers composites. Geopolymers have been studied for the past decade due to its unique properties such as low shrinkage, substantially chemical resistance, and higher fire resistance. The geopolymer offer an innovative for coating application at higher thermal application. Based on historical review, geopolymer materials exhibit resistance to corrosion, abrasion and heat. This paper summarizes some research finding about alkali-activated binders over the past decades along with outlines of the potential of geopolymer composites for high temperature application.