Physico-Mechanical Properties and Weathering Performance of Coconut Husk Fibre-Reinforced Composite Roofing Tiles Produced with Selected Cement Admixtures

Abstract

AbstractRoofing constitutes a major cost item in building construction. The relatively high cost of conventional roofing materials is a factor militating against affordable housing provision in sub-Saharan Africa. This study examined the physico-mechanical properties and weathering performance of coconut husk fibre-reinforced composite roofing tiles produced with selected cement admixtures. Corrugated (40 × 30 × 0.6 cm3) and flat (16 × 30 × 0.6 cm3) roofing tiles were produced using Rice Husk Ash (ASH), Chicken Eggshell Ash (CESA) and Calcium Carbide Waste (CCW) as a partial replacement for Portland Limestone Cement (PLC). Formulations used were 4% coconut fibres by mass of cement, 0.4 for cement–water ratio and 1:2 for cement–sand. Cement admixtures were formulated at 90%PLC + 10%RHA; 90%PLC + 10%CESA; and 95%PLC + 5%CCW. All these were thoroughly mixed together and poured into a mould and covered with a polythene sheet. Composites were demoulded after 24 h, immersed in CO2-injected water inside a controlled chamber for 4 min at 5.5 MPa and damp cured for 21 days. Three replicate samples were tested for density, Water Absorption (WA), Thickness Swelling (TS), Modulus of Elasticity (MOE) and Modulus of Rupture (MOR). Corrugated and flat tiles were installed on a pitched roof structure and exposed to natural tropical weathering conditions for 24 months in Ibadan, Nigeria. Weather data were collected and triplicate samples of the installed roofing tiles were tested for density, WA and TS at 90-day intervals. Composite density (1.9–2.0 g/cm3), WA (7.5–8.7%) and TS (7.8–11.1%) were relatively high. Partial replacement of cement with RHA, CCW and CESA slightly reduced the density and TS but significantly increased the WA (p ≤ 0.05). The MOE (1.5–2.8 GPa) and MOR (1.4–5.0 MPa) were relatively low. However, RHA and CCW significantly increased MOE and MOR. Temperature, relative humidity and rainfall values for the weathering test duration were 28.8- 33.4 °C, 13.0–88.5% and 5.1–16.4 mm respectively. All installed tiles exhibited a minimal reduction in density (<0.6 g/cm3), WA (3.0–4.6%) and TS (approximately 3%). Flat roofing tiles containing 10%RHA gave the best overall performance.KeywordsCoconut huskRice husk ashEggshell ashCarbide wasteRoofing tiles