This document summarizes a presentation on determining the mechanical properties of lightweight concrete with partial replacement of cement with marble powder. It describes experiments conducted to test the compressive strength, split tensile strength, flexural strength, and impact strength of conventional concrete and coconut shell concrete with the addition of marble powder and coconut fibers. The results showed that both concretes saw improvements in mechanical properties with the partial replacement of cement with 5% marble powder and addition of 2-3% coconut fibers. Using these materials provides benefits like utilizing waste products, reducing environmental damage, and producing more economical, lightweight concrete.