Design Mixture of Interlock Concrete Bricks using Pulverized Oyster Shell as a Partial Replacement for Cement and Rice Husk Ashes for Fine Aggregates

The Barangay Barra, Lucena City is a coastal community. There are some areas there that experience flooding during heavy rains due to their undeveloped pathways. Moreover, as the researchers desired to contribute to the goal of sustainable communities and lessen the environmental challenges, agricultural wastes were utilized to create beneficial and suitable material for the target community. Therefore, the researchers conducted a study in which Pulverized Oyster Shells (POS) and Rice Husk Ashes (RHA) were used as partial replacements for cement and fine aggregates to create interlock concrete bricks for pathways and driveways. The ratio used in this study was 1:2:4 with design mixtures of 0% both RHA and POS (Mixture 1), 5% RHA 15% POS (Mixture 2), 10% RHA 10% POS (Mixture 3), and 15% RHA 5% POS (Mixture 4). The interlock concrete bricks were cured for 7,14, and 28 days before testing. Various tests were conducted including compressive strength and water absorption in Mega Testing Center Inc. in Lucena City using ASTM C67 as the Test Method and ASTM 902 as the Standard specification. It was determined that the compressive strength of Mixture 1, Mixture 2, Mixture 3, and Mixture 4 after 28 days were 18.99 MPa, 29,69 MPa, 33.15 MPa, and 29.46 MPa with water absorption of 4.08%, 3.57%, 2.98%, and 3.28% respectively. Upon evaluation, the 10% RHA 10% POS as Mixture 3 obtained the most effective interlock concrete bricks as it has the highest compressive strength and lowest water absorption. Moreover, it demonstrated the most economical and cost-efficient design mixture among the samples.