Cement and Sustainability
Ordinary Portland Cement (OPC) is the grey powder that is mixed with water, rock and sand to create concrete, and is the largest commodity product on the planet with over 2.5 billion tonnes produced annually. It is also the third largest source of man-made CO2 emissions, representing approximately 5% of all emissions.
OPC is the dominant source of CO2 emissions from concrete (70%+) and the primary source of emissions in road, infrastructure and construction projects - around 20 - 40% of total project emissions according to the state of Victoria's roads authority, VicRoads, and other bodies' internal investigations. This makes reducing the amount of OPC used to make concrete a top priority. Zeobond can totally replace OPC!
OPC is made primarily of 60% CaO, 40% SiO2 and some Al2O3, Fe2O3 and SO3. The source of calcium is limestone, which is mainly calcium carbonate, CaCO3, and is obtained through quarrying.
In manufacturing a tonne of OPC approximately 0.60 tonne CO2 from the CaCO3 CaO + CO2 calcination reaction. In addition, approximately 0.40 tonne CO2 is produced from fossil fuels used to generate the energy to heat the materials to 1400 degrees C. In total the manufacture of a tonne of OPC therefore emits approximately 1 tonne CO2.