Sugarcane waste concrete cuts CO₂ by up to 30% while boosting strength

According to the United Nations, the global population is set to reach around 10.3 billion by the mid-2080s, driving rapid urbanization and an unprecedented demand for infrastructure. But do you know that this growth comes at a cost? Energy-intensive industries which supply construction materials like steel, cement, and chemicals are undoubtedly a major source of global carbon dioxide (CO₂) emissions and industrial emissions.

Among these industries, cement remains the single largest contributor to emissions. The production of Portland cement alone generates about 7% of global CO₂ emissions, largely from clinker manufacturing, where limestone is heated and releases carbon dioxide. As construction demand continues to rise, finding cleaner, more sustainable building materials has become an urgent global priority.

Now, a study by Dr. Fakhruddin, a Lecturer at Hasanuddin University, Indonesia, proposes a new type of concrete made from sugarcane waste as a sustainable alternative to conventional cementing materials. In this study, Dr. Fakhruddin studied the effect of sugarcane bagasse ash (SCBA), a by-product of sugar production, when combined with fly ash and polypropylene (PP) fibers and found that it creates geopolymer concrete (GPC) with improved mechanical performance, microstructural behavior, and eco-efficiency. The study was published in Results in Engineering on March 1, 2026.

Globally, more than 1.8 billion tons of sugarcane are processed each year, generating large quantities of SCBA. Instead of discarding, this ash can be reused as a key ingredient in GPC (which is inherently brittle and prone to cracking despite being an eco-friendly material), where it reacts with alkaline solutions to form a strong binding material. PP fibers are added to improve its strength, and they act as tiny bridges that prevent crack progression, improving the concrete's tensile strength, ductility, and crack resistance.

However, the combined effect of SCBA and PP fibers on geopolymer concrete had remained poorly understood. The current study addresses this gap by examining how these materials work together and influence the structure and performance of the concrete.

"This is the first time that SCBA and PP fibers were integrated in Class C fly ash-based GPC under ambient curing, directly linking mechanical enhancement, microstructural densification, and environmental efficiency," says Dr. Fakhruddin, elaborating further.

Dr. Fakhruddin created three different mixtures of Class C fly ash-based GPC, replacing 0%, 5%, and 10% of the fly ash with SCBA, while keeping the fiber content at 0.6 kilograms per cubic meter. Each mixture was then evaluated for compressive, tensile, and flexural strength, and their internal structure was analyzed using scanning electron microscopy. The environmental impact of the mixtures was also evaluated, considering the carbon emissions and the economic cost.

The results showed that the mix with 5% SCBA (SCBA-5) performed the best overall. It had 41% higher compressive strength, 29% higher tensile strength, and 56% higher fracture energy than the standard mix, which contained no SCBA (SCBA-0). In contrast, the mix with 10% SCBA (SCBA-10) improved the flexural strength by 9.3% but increased brittleness.

Notably, SCBA-5 also demonstrated environmental benefits, with a 52% higher strength-to-carbon ratio and 53% higher strength-to-cost ratio, while achieving a 25–30% reduction in CO₂ emissions compared to conventional Portland cement concrete.

"The SCBA-5 replacement mix consistently delivered the most favorable balance of strength, ductility, and durability, making it suitable for structural applications such as low-rise buildings and non-prestressed members," says Dr. Fakhruddin, highlighting the practical relevance of this study.

Although the study did not test the long-term durability of the material, it provides a foundation for future research and real-world use. "Expanding the use of GPC can help reduce carbon emissions, lower costs, and support sustainable construction practice, aligning with a UN Sustainable Development Goal 12 (SDG 12): responsible consumption and production," says Dr. Fakhruddin.

Such a concrete mix is particularly relevant in developing regions experiencing rapid urban expansion. A key example is Indonesia, where the government is shifting the capital from Jakarta to Nusantara in East Kalimantan, citing concerns of flooding, overcrowding, and traffic congestion. Incorporating low-carbon construction materials could significantly reduce the environmental impact of such developments.

Moreover, in sugarcane-producing regions, adoption of SCBA can also promote a circular economy, creating a win-win situation by improving cost efficiency for the consumer and reducing the burden of agro-industrial waste disposal as well as emissions for the industry.

Provided by Hasanuddin University