Enhancing traditional construction materials with waste products has become a research focus in the construction industry in recent decades to meet the challenges of modern society. Organic waste is one of the most commonly produced waste streams in the world, and its use in construction materials can help to achieve the circular economy goals of many industries. This article will give an overview of some of the uses of organic waste to enhance cement.
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Issues with Traditional Construction Materials
The construction industry uses vast amounts of natural resources in building projects worldwide. Steel, concrete, wood, and glass are just some of the commonly used building materials today. Concrete, which is employed in the building of structures from small silos and domestic dwellings to towering skyscrapers and massive infrastructure projects such as dams and power stations, is an especially problematic construction material.
Concrete is traditionally manufactured from water, aggregate materials, and Portland cement. This conventional manufacturing process is environmentally harmful, accounting for around 7% of global greenhouse gas emissions according to the IEA. Moreover, concrete manufacturing damages topsoil, which is essential for food security.
Another issue with the construction industry is waste. Once a building or infrastructure project reaches the end of its life, several tons of material is wasted, which is usually disposed of by incineration and landfilling. Moreover, before a building is operational, 35-51% of its total lifetime carbon production is embodied in the construction materials. Furthermore, the continued exploitation of finite construction materials is causing a growing supply issue worldwide.
The construction industry as a whole exploits around 14-50% of all extracted natural resources and is widely considered to be the second biggest contributor of carbon emissions behind the energy industry. In recent decades, waste materials have been increasingly researched as cementitious additives.
How Can Waste Materials Overcome these Issues?
Waste materials offer a simple solution to the challenges of the modern construction industry. By replacing aggregates and ordinary Portland cement, more sustainable concrete can be manufactured. Waste is eliminated, emissions are vastly reduced, and the properties of concrete can be enhanced with novel functionalities such as carbon storage potential. This strategy significantly improves the circular economy goals of the construction industry.
Many waste materials have been explored as additives in green concrete. Examples include rubber, fly ash, PET wastes, glass, copper slag, construction demolition waste, and by-products of the steelmaking and agricultural industries. However, construction requires materials with superior mechanical, physical, and chemical properties. For waste materials to be considered as replacements for ordinary Portland cement, they must meet or exceed these material requirements.
Organic waste products are produced from the incineration or processing of agricultural and food products as well as by industrial processes and from municipal waste streams. Research in recent years has highlighted the potential benefits that organic waste can bring to the construction industry as replacements for conventional cementitious materials.
Utilizing Residual Ash from Solid Organic Waste Combustion
Ash is produced from the combustion of solid waste materials such as municipal waste. Incinerating municipal waste has been widely used for electricity generation in several industrialized nations, and regulations exist which govern the use of residual ash in construction.
Several studies have explored the potential of this organic waste stream as cementitious material replacements in different composition amounts. Research has indicated that a 20% replacement by weight of conventional cement with incinerated residual ash improves the compressive strength of concrete compared to control specimens. Other studies have shown that heating a 30% ash replacement for 2 hours at 1200oC produces high-quality clinker.
Whilst incineration is the main approach to producing organic ash, chemical decomposition has been explored by some researchers. Research has indicated that residual organic powder fills voids, decreases porosity, and provides a smooth texture. Studies are underway to evaluate the performance of green cement prepared with organic residual ash.
Using Food and Agricultural Waste Materials
Another solution to the problem of reducing the environmental impact of cement production and improving the sustainability of concrete use in the construction industry is to use fibers extracted from vegetables. The food and agriculture industry produces vast quantities of vegetable waste every year globally, with most of this valuable organic waste either being incinerated or going to landfill sites.
There is evidence that waste vegetable material may increase the strength of concrete compared to conventional cementitious materials, as well as reduce energy and water consumption and carbon emissions.
A recent study, which was given funding by the EU’s Horizon 2020 framework program for research and innovation, investigated the benefits of using waste root vegetable materials as cementitious replacement materials. The research produced cheap, green concrete with improved strength. The addition of nanosized particles from this organic waste stream enhanced the production of calcium silicate hydrate in materials. Moreover, the study demonstrated that 40 kg less Portland cement was needed per cubic meter of concrete.
An Organic Approach to a Critical Issue
The use of organic waste residues and cementitious replacements offers significant benefits for the construction industry. They improve the carbon footprint of cement and concrete manufacture, reduce the need for virgin resources, provide enhanced mechanical properties and functionalities, and offer significant cost savings for the industry.
If global climate change and the environmental impact of modern industry are to be mitigated, innovative circular economy approaches must be implemented in sectors such as the construction industry. Valorization of global organic waste streams provides part of the answer to the current problems facing policymakers and commercial stakeholders today. Research is ongoing in this field, with aims to help the construction industry meet its net-zero carbon commitments by 2050.
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References and Further Reading
Ho, S (2019) Concrete Made From Carrots: How Food Waste Can Help Make Buildings Stronger [online] greenqueen.com.hk. Available at:
Soto Izquierdo, I (2016) Use of residual powder obtained from organic waste to partially replace cement in concrete [online] Researchgate.net. Available at:
Kalaivani, S et al. (2019) Application of Organic Waste in Concrete International Journal of Innovative Science and Research Technology 4(4) [online] ijirst.com. Available at: