Eco-Friendly Production of Decorative Concrete Blocks Using Coal Fly Ash and Coconut Husk Fiber Admixtures: Mixture D-Optimal Design Optimization

The present study investigates the production of decorative concrete blocks using coal fly ash and coconut husk fiber as admixtures to cement and sand. Using the Mixture D-optimal design, the decorative concrete blocks with a volume of 3,350 cm(3) were produced by varying the amount of coal fly ash (2.33-28.33 wt.%) and coconut husk fiber (3-9 wt.%) while using a constant amount of 10% of cement and 58.67% of sand throughout the study. These were cured for 28 days and tested in terms of compressive strength, density, and water absorption capacity. Results revealed that the density of the produced decorative block at optimum conditions was 1153.27 kg/m(3), which is lighter than the commercial one, which was 1165.39 kg/m(3) because of the raw materials used. Meanwhile, a high water absorption capacity was recorded at 24.79%. Furthermore, the recorded compressive strength of 0.467 MPa of the produced block is higher than the commercial one with 0.453 MPa, which means that this can replace them, considering its lower production cost. This study presents an innovative approach to utilizing industrial waste materials and producing a new product that can reduce solid waste generation and environmental pollution.