Properties of concrete block containing coconut fiber and coconut powder

Abstract

This research aimed to study the properties of concrete blocks using coconut fiber and coconut powder as replacements for stone dust, compared to standard blocks, in terms of net compressive strength, density, water absorption, thermal conductivity, and temperature reduction. Coconut fibers (diameter ≤0.25 mm, length 2 cm) and finely ground coconut husk (passed through a standard No. 4 sieve) replaced stone dust at 5%, 10%, 15%, and 20% by volume. The blocks were air-cured and tested at 7, 14, and 28 days.

Results revealed that 5% replacement of stone dust with coconut fiber and powder were the highest net compressive strength (9.57 MPa), lowest water absorption (2.62%), and highest density (2184 kg/cm³) across all curing ages. Mixtures with 5% coconut fiber alone exhibited higher compressive strength than those with coconut powder alone, as fibers enhanced cohesion and delayed crack propagation. However, exceeding 5% replacement reduced compressive strength and density while increasing water absorption, attributed to internal voids from excessive fiber and husk content. Additionally, the mixture with a 5:10 ratio (fiber-to-powder replacement) demonstrated the lowest thermal conductivity and highest temperature reduction capability. In conclusion, partial replacement of stone dust with 5% coconut fiber and powder optimized mechanical and physical properties, while higher replacement ratios compromised performance. These findings suggest potential for sustainable construction materials using agricultural waste.