Rice husk ash (RHA) emerges as a multifaceted contributor in the realm of construction. This humble byproduct of rice processing serves a dual purpose, acting both as a cost-effective substitute for Portland cement and as a valuable admixture in crafting high-strength concrete.
Crucially, the RHA employed in concrete construction is amorphous, showcasing pozzolanic activity. This amorphous nature distinguishes it from the crystalline variant, rendering it suitable for enhancing concrete properties.
Low-Cost Building Blocks : The financial constraints faced by developing nations often call for affordable building solutions. Rice husk ash offers a compelling alternative to the pricey Ordinary Portland cement. By substituting a portion of cement with RHA, concrete costs can witness a substantial reduction. Notably, a 50% replacement of cement with RHA has been shown to cut concrete costs by a significant 25%. An Indonesian company successfully employed a mix with 10% cement, 50% aggregate, and 40% RHA, resulting in blocks with an average strength of 12MPa.
Refractory Bricks : Leveraging its insulating properties, RHA finds application in the production of refractory bricks. Serving as an organic filler, RHA aids in creating lightweight, porous refractory bricks. These bricks, resistant to extreme temperatures, find utility in furnaces.
Lightweight Construction Materials : The integration of RHA into concrete formulations yields higher-strength concrete, facilitating the production of lightweight products. Notably, hollow blocks with improved thermal insulation properties become feasible, contributing to the construction of lighter walls for steel-framed buildings. Additionally, this approach leads to reduced quantities of cement and aggregate, with RHA being instrumental in the creation of lightweight insulating boards.
Insulating Material : RHA extends its utility as a loose insulant, finding applications in dwellings, farm structures, and cold storage plants. Through treatment with a boric acid and borax solution, RHA can be flameproofed. The insulating value of rice hulls proves to be notably high.
Soil Improvement : When combined with a small quantity of cement, RHA becomes a valuable tool for shallow stabilization, contributing to soil improvement in construction projects.
Steel Industry : In the steel industry, RHA plays a crucial role in the production of high-quality flat steel. Its application as an insulator is underlined by desirable characteristics such as low thermal conductivity, high melting point, low bulk density, and high porosity. RHA aids in preventing rapid cooling of steel, ensuring uniform solidification. However, health concerns arise due to the oxidation of elements in steel, such as aluminum, forming alumina (Al2O3).
The versatile applications of rice husk ash underscore its significance as a sustainable and cost-effective building material, addressing a spectrum of construction needs with ingenuity and efficacy.
