Influence of coconut husk on mechanical properties as a filler with polyurethane foam in the sandwich panel—an experimental study

To reduce the environmental impact of construction, use of waste materials has become popular in building applications. In this study, waste coconut husks (CHs) and calcium silicate boards (CSB) are incorporated into a sandwich panel using polyurethane foam (PU) as binding material. PU is made up of A (isocyanate) and B (polyol), which are mixed at a ratio of 1:1.2. To determine the optimum replacement level, PU was replaced with CH at 10, 20, 30, 40 and 50%. A sandwich panel with an outer dimension of 30 × 30 cm and a core thickness of 2 and 3 cm was prepared and tested for its mechanical properties, thermal properties, durability properties and characterization study. The microscopic image showed that the replacement of PU with CH at 50% showed maximum reduction in porous size, but its composite has achieved higher compressive strength at 20%. Hence the optimum percentage of replacing PU with CH is found to be 20%. Further, analytical work was carried out to validate the experimental results through regression analysis and suitable threshold with an accuracy of R 2 > 0.90 was obtained.