Contains the full lesson along with a supporting toolkit, including teachers’ notes.
Industry and the Environment
Currently there is widespread concern about the long-term sustainability of industrial activities that affect the environment. The science and technology we use to produce the goods and services we need can impact soil, water and air. In this lesson we look at how CRH, the major global building materials company, fulfils itscorporate social responsibility as it works to reduce or ameliorate the environmental impact of its business operations.
Cement – The Essential Building Material
Cement is produced by burninglimestone (calcium carbonate, CaCO3), together with other raw materials, mainlyshale, in a kiln. Modern cement kilns operate at temperatures up to 1450°C which are necessary to produce the kiln output calledclinker. The clinkeris then mixed with small amounts of gypsum and ground to the fine powder that we recognise as cement.
The cement production process emits carbon dioxide (CO2) through the decomposition of limestone into carbon dioxideand lime (CaCO3 ⇒ CO2 + CaO), and from the burning of the fuels necessary to create the high temperature in the kiln. Of all the CO2produced in the production of cement, about 60% comes from the chemical process described above and 40% from the burning of fuels. Approximately 700 kg of CO2 are emitted for every 1000 kg of cement produced. It is estimated that cement accounts for 5% of global CO2 emissions but the industry has a number of programmes in place to minimise this figure. Today clinker is ground with materials such as unburnt limestone to reduce the emissions footprint in production. CO2 is classified as agreenhouse gas (GHG).