Estimation of the addition of fly ash and its environmental impact in the manufacture of cement pastes

The cement industry is one of those that consumes the most energy, due to the high temperatures required to produce this material, and it is also one of the most that generates high CO2 emissions. In this work, the addition of sugarcane ash, bituminous coal and hazardous residues in cement pastes were evaluated. For this, cement pastes were produced in accordance with ASTM C305, from which the test specimens were prepared to analyze compressive strength and parallel to this, metal leaching tests were performed using the SPLP procedure. Following this, the reactivity of the fly ash in the cement pastes was evaluated by means of thermogravimetric tests. The different analyzes were carried out at the ages of 1, 3, 7, 14, 28, 56, 90 and 180 days. The ashes were characterized by XRF, XRD, and laser grain size, where the SiO2 and Al2O3 contents in the cane and bituminous coal ash were relatively high, contrary to what was obtained in the treated and untreated hazardous waste ash. These results are quite innovative because there are few works using HW in the literature. Cements with CAN, BIT, and THW5 were found to show equivalent and even superior compressive strength performance when compared to control. This work can be used as a guide and an inspiration for policymakers who want to apply this kind of material in the cement sector and promote evidence-based decisions and regulations.