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Based on alternative CO2-functional cement chemistry
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Ordinary portland cement (OPC) production is a significant contributor to global greenhouse gas (GHG) emissions. In fact, the cement industry is the second-largest industrial GHG emitter. World cement production reached 4.10 x 109 tonnes (4.5 x 109 tons) in 20191 and is estimated to contribute about 8% of total anthropogenic carbon dioxide (CO2) emissions worldwide.2
During the United Nations Framework Convention on Climate Change (UNFCCC) COP 21 meeting in Paris, France, member nations agreed to the goal of keeping the global temperature rise within 2°C (3.6°F) of the preindustrial era level by the end of the twenty-first century (The Paris Agreement).3 Following the International Energy Agency's guidelines to meet this scenario, the World Business Council for Sustainable Development's Cement Sustainability Initiative group, now part of the Global Cement and Concrete Association, developed a Global Technology Roadmap called "Low-Carbon Transition in the Cement Industry."4 This roadmap has set a target to reduce the CO2 emissions from 2.2 x 109 tonnes (2.4 x 109 tons) in 2014 to 1.7 x 109 tonnes (1.9 x 109 tons) by 2050. This goal was set despite a predicted 12 to 23% growth in worldwide cement production during this period. To achieve this goal, a radically new approach to cement manufacturing and use must be undertaken, and an alternative CO2-functional cement chemistry must be found.
This article describes the CO2 savings in the production of Solidia Cement™ (SC) and CO2 use during the production of SC concrete.
Cement and CO2 Emissions Portland cement
OPC clinker is produced by burning a mixture of calcareous and siliceous raw materials. Calcareous material (such as limestone) and siliceous materials (such as sand, clay, or similarly composed materials) are ground and sintered at a temperature of about 1450°C (2642°F) in a rotary kiln. The resulting clinker nodules are then ground with about 5% gypsum to produce cement. OPC production emits CO2 by two direct mechanisms:
* The decomposition of CaCO3 to produce CaO(s) and CO2(g); and
* Burning of fossil fuels to achieve the sintering temperature in the kiln.
CO2 emissions are also indirectly created during the mining, transportation, crushing, and grinding of raw materials to create the raw meal feed to the kiln...