Innovative Mix Designs Using Coconut Shell, Sawdust, and Fibers for Lightweight High-Strength Concrete

Abstract

Being the most widely used construction material, concrete is basically strong in compression but weak in tension and heavy in weight. Hence lightweight concrete was developed as an alternative. This work studies the use of sustainable materials such as coconut shell and sawdust-the agricultural and industrial waste-for the purposes of reducing the density of concrete and enhancing its property. The coconut shell was used as a replacement of coarse aggregate and it reduces the weight of concrete by about 25%. Sawdust was used to replace partially the fine aggregate at four levels: 0, 5, 10, and 20% in both normal concrete and coconut shell concrete. The M25 mix was adopted, and determination of compressive strength was made after 3, 7, and 28 days. The results indicated that the compressive strength decreases with the increase in sawdust content and the best replacement was found to be 5% for either concrete. At this sawdust level, coconut fiber was added at 1, 2, 3, 4, and 5% to enhance tensile properties and crack resistance. Adding coconut fiber improved the strength properties with the notable improvement observed at 2% fiber in coconut shell concrete and 3% in normal concrete. This research clearly emphasizes the prospects of utilization of agricultural waste materials toward the development of eco-friendly, lightweight, and high-strength concrete, while retaining environmental problems with related to waste disposal.