Utilization of Coconut Shell Ash as a Substitute Material in Paving Block Manufacturing

In this study, coconut shell ash (CSA) was used as a substitute for cement in the manufacture of paving blocks. The research aims to determine the CSA substitution effect on the mortar compressive strength. The replacement percentages were 0, 3, 5, 8, 10, and 12%. The immersed and wrapping with plastic were conducted as curing conditions. The mortar compressive strength was 24.97, 16.44, 15.26, 14.61, 14.25, 11.87 MPa for immersed curing at 28 days for 0, 3, 5, 8, 10, and 12%, respectively. While for wrapping plastic, the compressive strength was 21.97, 15.82, 15.10, 14.06, 13.21, and 12.62 MPa. Substitution of coconut shell ash reduced the compressive strength. Based on the optimum compressive strength of mortar, the paving block size of 20x10x6 cm was made and then cut into 6x6x6 cm. The compressive strength was 13.21, 12.02, and 9.65 MPa at the 0, 3, and 5% CSA substitution. The water absorption indicated almost similar around 7% for all substitutions. There were no defects such as cracks found, and the different weights before and after immersed in sodium sulfate were 0.1 to 0.3%.