Substitution of Sand in Concrete Blocks with Coconut Fiber and Cattle Manure: Effects on Compressive Strength and Thermal Conductivity

Abstract

Improving the energy performance of buildings is critical in the construction sector. This study investigates the effects of incorporating coconut mesocarp fibers (F = Fiber) and bovine manure (M = Manure) on the thermal conductivity and compressive strength of concrete blocks. Bovine manure and coconut fiber replaced the block sand at maximum concentrations of 10 and 1.5%, respectively. Thermal conductivities were measured according to the ASTM C177 (2013) standard, compression tests were performed using the ASTM C140 standard, and characterization assays such as Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were performed to determine the morphological properties of the final material and its constituents. The results showed a 50% reduction in the thermal conductivity coefficient of the blocks when 10 and 1.5% of the sand was replaced with manure and coconut fiber, respectively. Similarly, incorporating coconut fiber at percentages of 0.5, 1, and 1.5% improved compressive strength results. Blocks comprising 0.5, 1, and 1.5% fiber or a mix of 3% manure and 1.5% fiber attained the compressive strength requirements established by the standard. This study demonstrated the feasibility of using coconut fiber mixed with cattle manure as a substitute for up to 2.5% of the sand in non-structural wall elements manufacturing, attaining a decrease in thermal conductibility of around 10%.

Keywords

• bovine manure
• coconut fiber
• masonry blocks
• sustainable construction
• thermal insulation materials