Carbon-Negative Cement and Bricks: Gemstone Olivine Traps CO2.
- October 15, 2024
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A recent study finds that olivine, the mineral responsible for the bright green in the gemstone peridot, has the potential to significantly cut the carbon footprint of the building industry, which alone accounts for 37% of worldwide CO2 emissions.
The researchers of the study demonstrated that olivine may be utilized to create cement that is robust, long-lasting, and carbon-negative.
Additionally, goods made from this mineral can take the place of gypsum boards and clay-fired bricks, two widely used but also very carbon-intensive building materials. We may be able to cut world emissions by over 11% if we switch from cement and bricks to olivine-based substitutes (cement and bricks account for eight and 2.7 percent of emissions, respectively).
The abundance of olivine on our planet is the finest aspect. Olivine predominates in the igneous rocks that make up the majority of the ocean floor and the upper mantle, the layer that lies between the Earth's crust and core.
The Problem with Traditional Cement and Bricks
Limestone, water, and clay are used to make cement. After being mixed, ground, and cooked at high temperatures, these materials generate a large number of little lumps that are referred to as clinker. Materials like fly ash and gypsum are added to the clinker in the following step. After that, this mixture is processed into cement powder.
The primary binding ingredient in cement is clinker. When combined with water, the chemicals it contains enhance the strength and hydraulic qualities of the cement. But it also happens to be the primary source of emissions from industry. This is due to the fact that fossil fuels are used to power the blending, crushing, heating, and grinding of clinker.
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Clay and water are also used in the making of bricks. Bricks are baked at high temperatures between 1,000 and 1,200 °C (1,832 and 2,192 °F) in order to make them hard and durable. High levels of CO2 are released into the atmosphere as a result of this process, which also uses fossil fuels.
The manufacturing process of bricks and cement both needs a lot of water. A study found that up to 680 gallons of water are needed to produce one ton of regular Portland cement. The production process also fuels extensive clay mining, which degrades land, erodes soil, and eliminates biodiversity.
These most recent results are intriguing for this reason. According to the study's authors, carbon-negative cement and bricks can be made from amorphous silica and nesquehonite, two byproducts of olivine.