Recycling of rice husk waste for a sustainable concrete: A critical review*

The punitive environmental legislation set by the global community has shifted the direction of research involve in construction industry towards the utilization of secondary raw materials in designing and constructing new structures. Rice husk (RH) is a by-product obtained from the rice mill process whose generation accounts up to 200 kg per ton of rice. The existing literature showed the vast potential of using rice husk ash (RHA) as a replacement for cement or as admixtures. This paper aims to critically review previous studies on RHA as a waste material. The utilization of this waste in concrete contributes to nurturing more sustainable and greener development, thereby lessen carbon footprints and minimize solid waste disposal issues. A state-of-the-art-review of literature on the use of RHA is presented in this paper. The impact of RHA on the properties of concrete such as workability, density, compressive strength, flexural strength, splitting tensile strength, modulus of elasticity, durability properties as well as its impact on sustainability are compiled. In addition, the technical results are complimented with the microstructural analysis evaluated through scanning electron microscopy (SEM). From the data garnered, it is postulated that RHA beneficially enhance the mechanical strengths coupled with improvement of resistant to sulfate and acid attack. This paper advances novel recommendations and directions for future research towards the application of green RHA-based construction products.