Carbon-Negative Concretes & Artificial Aggregates

Abstract

The construction industry is one of the largest contributors to global carbon dioxide emissions, with ordinary Portland cement (OPC) production alone accounting for nearly 7–8% of total anthropogenic CO? release. In recent years, the concept of carbon-negative concrete has gained attention as a potential pathway to mitigate climate change while meeting the growing demand for infrastructure. Carbon-negative concretes are designed not only to reduce emissions during production, but also to actively capture and store carbon dioxide over their life cycle. Parallel to this development, artificial aggregates produced from industrial by-products, recycled wastes, and carbonated materials are emerging as sustainable alternatives to natural aggregates, whose extraction causes ecological damage. This paper presents a comprehensive review of carbon-negative concrete technologies and the role of artificial aggregates in achieving net-negative carbon performance. Various binder systems, including alkali-activated materials, magnesium-based cements, and bio-mediated binders, are discussed in terms of raw materials, processing, mechanical properties, and environmental benefits. Artificial aggregates derived from industrial wastes such as fly ash, steel slag, red mud, and municipal solid waste incineration ash are reviewed with respect to manufacturing techniques, physical properties, and compatibility with carbon-negative binders. Life cycle assessment (LCA) studies reported in literature are critically analyzed to understand the true carbon footprint of these materials. Challenges related to durability, scalability, cost, and standardization are also highlighted. The review concludes that carbon-negative concretes combined with artificial aggregates offer a promising route toward low-carbon and circular construction, though further research and field-scale validation are required for widespread adoption.

KEYWORDS: Carbon-negative concrete, artificial aggregates, sustainability, CO? sequestration, green construction materials