Combined effects of paper mill sludge and carbonation sludge on characteristics of fired clay bricks.

• Reusability of PMS and CS provides economic and environmental benefits. • PMS and CS can be utilized as a pore making agent in sustainable brick manufacturing. • The energy efficiency problem of buildings can be solved using the produced lightweight and thermal insulated bricks. • ANOVA revealed that the characteristics of the fired bricks depends on the selected mixture ratio. In terms of sustainable and cleaner production, the utilization of various industrial wastes in the manufacturing of eco-friendly building materials has attracted attention in recent years. In the present study, a total of 12 series bricks were produced to determine the influences of paper mill sludge (PMS) and carbonation sludge (CS) on the physical, mechanical and thermal properties of clay based bricks. The following parameters were examined for the bricks produced at 1000 °C and 1100 °C; water absorption, apparent porosity, efflorescence, bulk density, compressive strength and thermal conductivity. For the fired brick production, CS was used up to 30% while PMS up to 15%. The compressive strength of the fired bricks having 15% CS and 5% PMS content were in accordance with the standards. The thermal conductivity ranged from 0.742 W/mK to 0.155 W/mK. Also, the influences of waste concentrations on the quadratic model were analyzed using analysis of variance (ANOVA). The analysis results indicate that the firing temperature is the least important parameter affecting all properties of brick. The use of wastes up to 20% in the brick structure is an important step both in terms of reducing environmental pollution and protecting natural clay resources. [ABSTRACT FROM AUTHOR]