Evaluation of sustainable concrete paving blocks incorporating processed waste tea ash

Agricultural waste is a viable material that can be used as a cement replacement in the cement-based material, which is contributed to reducing the CO2 emission from cement production. In this study, processed waste tea ash (PWTA) as a cement replacement of paving blocks at dosages of 10 %, 20 %, 30 %, 40 %, and 60 % by weight of cement were investigated for the first time. Several testing were included for the workability, density, compressive and flexural strength, water absorption, acid attack resistance, and microstructure through SEM observation. Test results confirmed that the replacement of cement with PWTA decreased the quality of the paving blocks. Owing to the greater porosity of PWTA, it increases the void within paving blocks, which is associated with a decrease in the paving block properties as indicated by SEM observations. Although the strength of the paving blocks decreased with the PWTA replacements, the paving blocks containing 20 % and 40 % PWTA still met the minimum requirements specified by Indonesian National Standard for Class C (pedestrian areas) and Class D (garden areas), respectively. Therefore, incorporating PWTA as a replacement for cement allowed a more sustainable and low-cost paving block to be produced.