Evaluation of paper factory screen underflow sludge and power plant fly ash in concrete block production: Improvement of mechanical and physical properties

This study investigates the utilization of paper mill sludge (PS) and non-standard fly ash (FA) from power plants in the production of concrete blocks. Test specimens were produced by incorporating varying proportions of PS and FA into standard concrete block mixtures. The specimens were cured, using standard methods and tested at various intervals. The analysis results indicate that PS and FA, which are difficult to dispose of, can be used in structural elements at certain proportions. Additionally, FA incorporation improved the strength and workability of the concrete, and the water permeability remained within the targeted values with the inclusion of PS and FA. In conclusion, PS and FA provide acceptable properties for concrete block production, with the chemical and physical characteristics of the waste materials, mix ratios, and production parameters significantly affecting the outcomes. However, to increase the proportion of these wastes and enhance their positive contributions, further detailed studies are required, particularly focusing on mixing techniques and homogeneous formation.