Performance of TALABLOCKS: Cement Hollow Block with <i>Ostreidei </i>Shell additive<b></b>

This study investigates the potential use of oyster shells (Ostreidae) as an additive in the production of hollow blocks to enhance their mechanical and physical properties. Specifically, it assessed the effects of oyster shell incorporation on compressive strength and water absorption performance. An experimental–descriptive research design was employed to establish cause-and-effect relationships while providing a detailed characterization of the material's behavior. The experiment was conducted at ParksHub Hollow Blocks, Purok Dita, Bobon, Mati City, Davao Oriental, and laboratory evaluation was performed at Triple M Material Testing Center, Tagum City. Observations and measurements were systematically recorded using a logbook, and data were analyzed using Analysis of Variance (ANOVA) to compare the performance of “Talablocks” (oyster shell–enhanced blocks) with commercial hollow blocks. Results revealed a significant increase in compressive strength for Talablocks compared with conventional hollow blocks, indicating the potential of oyster shell powder to enhance load-bearing capacity. Visual observations during and after compressive strength testing showed no noticeable cracking or abnormal failure patterns in Talablocks, suggesting that the added oyster shell powder did not induce brittleness. In contrast, water absorption did not differ significantly between the two block types, indicating that although oyster shell addition may slightly increase hydration, it does not compromise material integrity or crack resistance. These findings demonstrate that oyster shell waste can be repurposed as an effective, sustainable additive in construction materials, reducing waste and promoting environmentally responsible hollow block production.