Potential Assessment of Utilizing Rice Husk Ash and Fly Ash in Concrete Production to Advance Sustainable Building Materials

Abstract

This study explores the potential use of rice husk ash (RHA) and fly ash as partial cement substitutes in concrete production, aiming to advance sustainable building materials and reduce the environmental impact of the conventional cement industry. Cement production currently accounts for approximately 8% of total global CO₂ emissions, making it one of the largest contributors to greenhouse gas emissions. Given the increasing demand for cement due to urbanization and infrastructure development, the search for environmentally friendly alternatives is urgent. Rice husk ash, an abundant agricultural waste in Indonesia with a high amorphous silica content (94-97%), has been shown to improve the compressive strength and durability of concrete, with 10% ASP substitution resulting in a peak compressive strength of 56.2 MPa at 28 days and 20% ASP reducing water absorption. Similarly, fly ash from coal-fired power plants, which is rich in pozzolanic silica and alumina, is effective in reducing cement use and CO₂ emissions, while increasing concrete density and resistance to extreme conditions. Utilizing these two types of waste not only reduces the carbon footprint of construction and the problem of waste accumulation, but also adds economic value and encourages a circular economy, thus creating a more sustainable and environmentally friendly construction future.