Abstract
In the last few decades, the demand for cement production increased and caused a massive ecological issue by emitting 8% of the global CO2, as the making of 1 ton of ordinary Portland cement (OPC) emits almost a single ton of CO2. Significant air pollution and damage to human health are associated with the construction and cement industries. Consequently, environmentalists and governments have ordered to strongly control emission rates by using other ecofriendly supplemental cementing materials. Rice husk is a cultivated by-product material, obtained from the rice plant in enormous quantities. With no beneficial use, it is an organic waste material that causes dumping issues. Rice husk has a high silica content that makes it appropriate for use in OPC; burning it generates a high pozzolanic reactive rice husk ash (RHA) for renewable cement-based recyclable material. Using cost-effective and commonly obtainable RHA as mineral fillers in concrete brings plentiful advantages to the technical characteristics of concrete and to ensure a clean environment. With RHA, concrete composites that are robust, highly resistant to aggressive environments, sustainable and economically feasible can be produced. However, the production of sustainable and greener concrete composites also has become a key concern in the construction industries internationally. This article reviews the source, clean production, pozzolanic activity and chemical composition of RHA. This literature review also provides critical reviews on the properties, hardening conditions and behaviors of RHA-based concrete composites, in addition to summarizing the research recent findings, to ultimately produce complete insights into the possible applications of RHA as raw building materials for producing greener concrete composites—all towards industrializing ecofriendly buildings.
Highlights
One of the most valuable and widespread cultivated cereal plants in the world is rice, which takes the second place after wheat in the total area size of cultivated areas [1,2,3].India and China are the largest producers of rice, accounting for about 49% of the total rice harvested worldwide [4]
The generation of rice husk ash (RHA) leads to several environmental issues, such as an increase in the disposal landfills and increase in the carbon footprints due to which a proper and safe disposal of RHA is obligatory for proper waste management
If rice husk (RiH) is combusted at about 700 ◦ C, a reactive amorphous RHA is obtained, which is suitable for use as pozzolan in composite binders [27]
Summary
One of the most valuable and widespread cultivated cereal plants in the world is rice, which takes the second place after wheat in the total area size of cultivated areas [1,2,3]. RiH is an agricultural by-product material from the rice plant and constitutes of about one-fifth of the rice weight; its structure consists of lignin (25–30%), cellulose (50%), moisture (10–15%) and silica (15–20%) [3], which upon burning generates a new waste, commonly known as rice husk ash (RHA). The properties of reactive silica present in the RHA may vary depending on the heat treatment temperature time. Production of sustainable and greener concrete composites has become a key concern in the construction industries globally This critical paper reviews the source, clean production, pozzolanic activity and chemical composition of RHA particles. This review aims to summarize the recent research findings to produce complete insights into the possible applications of RHA as raw building materials, for producing greener concrete composites and in so doing industrialize ecofriendly buildings. It is anticipated that the conclusions drawn from this review will bridge the gap between researchers and policymakers for a framework of codal provisions regarding the same
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