Characterization and Performance Evaluation of Masonry Hollow Blocks (MHB) Mixed with Clay from Two Sites in Bicol, Philippines

Objective: To investigate the impact of the use of local clay in partially replacing cement on compressive strength and physical properties of masonry hollow blocks (MHB) in the Bicol region, Philippines. This is to come up with sustainable and cost-effective materials to be applied in the non-load bearing masonry blocks without jeopardizing the required minimum strength. Methodology: Two types of clay (Plasticity Index = 13.95 and 20.65) were used and 0%, 5%, 8%, and 12% of clay substituted by weight with water-cement ratio maintained at 0.5. Molding of three block specimens of each mix were cured at 28 days, and the specimens were tested based on the American Society for Testing and Materials (ASTM) standards as: water absorption, moisture content, dry density and compressive strength. Results: As the percentage of clay replacement increased to 12% the percentage of water absorption also increased to 3.70% and the percentage of dry density reduced to 0.672%. Compressive strength revealed that both the control (4.35 MPa) and treatment B with Pulang Daga clay of 5% replacement (4.23 MPa) met the minimum required strength of non-load bearing concrete hollow blocks of 4.14 MPa. Among the varieties of the clay, Pulang Daga clay blends a higher retention of strength at the same level of substitution. Novelty: This is the first study to provide empirical region-specific data on the use of Bicol clays in the replacement of partial cement for MHB, as far as the knowledge is concerned. It demonstrates that it can be substituted with clay without violation of the norms. The outcomes demonstrate a more sustainable and cost- efficient construction method that will potentially reduce the cement dependency and carbon footprint of the resource scarce rural regions. Keywords: Masonry hollow blocks, Lightweight concrete, Clay properties, Concrete blocks performance, Clay substitute