Cement and Lime
Limestone is heated in kilns to extremely high temperatures to induce a chemical reaction that produces calcium oxide, or quicklime.
Quicklime is used in iron and steel manufacturing and for the production of aerated concrete blocks. It can also be processed into hydrated lime, which is used in a wide range of industries including construction and civil engineering, food and agriculture, chemical manufacturing, and water.
Cement is the most versatile building material in the world and is the second most used resource in the world, after water. Cement is used to create the built environment around us, from homes, offices and hospitals, to roads, airports, bridges and power stations.
Cement is essentially a binder and it can be mixed with aggregates, water and other ingredients so that it makes a concrete which sets and hardens as it dries to bind the other materials together.
The production process is now fuelled by coal, petroleum coke and over 50% waste derived fuels. To find out more about these sustainable fuels, go to the environment section.
Inside the kiln a complex chemical reaction takes place to form granules of ‘clinker’ which are then combined with gypsum and milled into the finished cement product.
Regulation and Governance
Our operation is strictly regulated by the Environment Agency (EA) through our environmental permit. We are required to meet UK legislation on air and water emission limits, and European legislation (the Waste Incineration Directive or WID) for our use of waste-derived fuels.
We have made significant improvements to our environmental performance by reducing levels of these emissions.
We have high-tech systems in place to monitor all aspects of our operation in great detail and in line with the requirements of our operating permit. With some of our emissions we have continuous (24-hour) monitors established and with others we are required to gather data ‘extractively’ on a regular basis as specified by EA.
At Tarmac we combine the knowledge and expertise of two of the construction industry’s most iconic brands: Tarmac, the pioneers of the modern road and Blue Circle the company that patented Portland Cement.
With over 150 years’ experience, we have many innovative achievements to our name: the invention of asphalt, a product that remains synonymous with our brand; the construction of the first motorway; the introduction of next-generation concretes and cements.
These breakthroughs all helped to shape the world we live in. Now we are working to help reshape it. Across our business, the wider supply chain and our research partners, we are looking at new ways to enhance productively, reduce carbon and value engineer efficiencies – whilst driving more sustainable construction.