Lime reduces climate change

Lime can reduce climate change

Carbon emissions could be reduced if we use lime in place of cement as cement production now accounts for 5% of the world’s emissions of CO2 - and the invertible expansion of the industry means this figure is on the rise. Most people are not even aware that making cement produces carbon dioxide.

Under pressure the cement producers now appear to be admitting they make unjustifiable contribution to the planets greenhouse-gas emissions and are being forced to reduce their impact on our fragile planet. But their efforts, such as burning waste products with coal, reworking recipes and trying to make plants more energy-efficient, have achieved only "little success".

You would be justified in saying that producers of cement "can't change the chemistry, so they can never achieve spectacular cuts in emissions”. But there is a substitute “a material that has been used for thousands of years and is well documented and has stood the test of time and it is called lime and was used by civilizations such as the romans for who’s building still stand to this day, it is should not be brushed aside as lime has the potential to play a leading role in its industry in carbon reduction.

Lime has been used for building for 10,000 years, whereas Portland cement was only invented in 1824. Rome has a lime concrete dome spanning over 43 meters that has stood tall for over 1,800 years, and there is a huge number of old buildings in Britain that are built with lime mortar, including a large amount of the better built and more attractive looking buildings.

The use of lime has been forced aside by the use of Portland cement during the late 19th and early 20th centuries. Cement sets faster and demands less skill in its application. Over the past 20 years, though, lime has enjoyed a revival after the harm caused to old buildings by cement became apparent. More recently, although the science of using lime concrete for engineered reinforced structures with large spans has yet to be developed, interest in the use of lime for new construction has grown as a result of its ecological credentials.

Lime requires less energy to produce than cement because limestone, the basic raw material, can be burned at lower temperatures - 900-1,000C rather than 1,300C or higher. Also, some of the CO2 created during firing is reabsorbed by lime as it hardens. And lime can be produced locally on a small scale, cutting pollution by limiting transport distances.

In contrast to cement, lime mortar is able to accommodate structural movement due to settlement or temperature changes in different seasons without significant cracking. This eliminates the need for expansion joints, which reduce the lifespan of many modern buildings because the sealant filling them deteriorates in sunlight and admits moisture. When buildings reach the end of their lives, lime is soft enough to allow the masonry to be taken apart and reused. Cement will potentially add to landfill problems for generations to come.

Last but not least, lime's ability to control moisture means it is compatible with low-energy, sustainable materials, such as water reed, straw, hemp, timber and clay.

The appropriate use of lime, therefore, can assist us both in conserving our past and creating buildings that are more green-friendly in the future.