Concrete has traditionally endured a poor reputation as a fundamental building material due to perceptions concerning its reliance on virgin raw materials and the energy consumption and emissions associated with its production process.
Based on recent developments, CEMEX UK’s Technical Director, Steve Crompton, argues that concrete should, instead, be viewed as a sustainable, strong, long-lasting, versatile and economically important construction material that has a vital part to play in the UK’s development of more sustainable communities.
Concrete is the most widely used construction material in the world. It is all around us; from offices to schools, roads to railways and dams to homes. Its powerful economic sway sees over 40,000 people directly employed in its UK manufacture, and it supports a construction industry employing seven per cent of our population.
However, when it comes to considering its sustainable credentials, which will ensure that we balance our current rate of development with the resource requirements of future generations, it is important to look at ready-mix concrete from several angles: its environmental and lifecycle aspects, its economic impact and its contribution to our society in general. Taking the environmental aspect first.
There is clear evidence that improvements in environmental performance are underway to minimise the impact of concrete production. These changes include actively reducing the emissions associated with the concrete manufacturing process, and lower the reliance on virgin raw materials by increasing the use of by-products in concrete.
Add in better management of waste, the use of more recycled aggregates and alternative fuels, as well as the thermal mass of concrete, which in the face of climate change, can help keep future housing cooler in summer than lightweight houses, whilst also saving heating fuel in winter, it is clear that concrete has a fundamental part to play in helping to deliver the energy efficient buildings of the future.
While total construction industry impact accounts for 10 per cent of total UK CO2 emissions, concrete is responsible for just 2.6 per cent of this. Compared to the 33 per cent generated by transport, this is a relatively small amount, especially considering its importance as a basic construction material.
Concrete also comes out favourably when compared to structural steel, where the amount of CO2 generated per tonne is approximately 10 times greater than that of reinforced concrete.
The use of waste products from other industries, such as ground blast furnace slag or fly ash, either as a mixer addition or incorporated in factory-blended cement significantly reduces the overall greenhouse gas emissions, and means that this essential building material is, and will continue to make, a significant contribution to the Government’s UK Climate Change Programme of driving down CO2 emissions by 60 per cent by 2050.
In addition to actively consuming waste products from other industries and processes, the industry is working towards improving production plants and compliance with international standards, such as ISO 14001, to prevent pollution and ensure continual improvement through the implementation of environmental management systems (EMS).
Use of recycled water at production plants is also on the increase and is increasingly commonplace. It’s not only the environmental aspects of concrete that should be assessed as sustainable and positive, however, so let’s consider its overall lifecycle. Like other building materials, concrete has a life span.
When compared to other commonly used construction materials it is by far the most durable, with a typical design life of at least 60 years. It essentially has three phases of life. Its creation, its use in buildings and structures, and its reuse through recycling once the building comes to the end of its life. It is far more likely that a modern concrete building will be deemed obsolete due to no further perceived usage, than the concrete fabric of the structure having failed due to age. With this in mind, and with cost-efficiency and sustainability now to the fore, reuse of concrete buildings is ever more commonplace.
The material offers flexibility and seemingly redundant concrete structures can be worked on, redesigned and rebuilt with new up-to-date specifications. However, if demolished, the resulting aggregate can also be used for a number of applications as a ready-made and important recycled material.
Contrary to popular belief, all rubble does not end up in landfill after a building’s demolition. Anything up to 95 per cent of a building’s components can in fact be recycled, including the most heavily reinforced concrete.
Indeed, recycled concrete aggregates (RCA) has proven performance characteristics and is being used in the ongoing production of new concrete – thus completing its life circle. New European Standards have cleared the way for greater use of recycled concrete aggregates in the manufacturing process, supporting UK Government targets of increasingly meeting construction demand with material from secondary and recycled sources. From an economic point of view, concrete and its sustainable credentials are well matched.
To improve their sustainability credentials, products should be consumed as near to the place of production as possible. This country’s self sufficiency in providing the core materials required for concrete production means that inbound raw material transport and import levels are kept to a minimum.
More often than not, the concrete industry uses locally sourced materials for local construction projects, thereby minimising transport related impacts. Compare this to timber, which imports over 98 per cent of the total volume used in UK construction.
With increased pressure on conserving fossil fuels, such as coal, for future generations, rising energy costs and changes to our climate, concrete can contribute positively by offsetting the heating up of buildings (especially in summer). Concrete’s high thermal mass can help absorb the heat generated by people, computers, lighting and electrical equipment, and keep internal temperatures lower.
The thermal mass in concrete walls and floors stores energy from the sun and the building’s own heating system, and releases this at night, thereby sustaining warmer overnight temperatures and reducing the need for heating. Finally, from an economic standpoint, as a self-sufficient producer of this material and a UK net exporter of concrete and component materials, concrete more than holds its own against other important materials.
Concrete offers many virtues to our society as a whole. It produces natural light when used in exposed areas within a structure, and reduces the need for artificial lighting. It is naturally inorganic and inert, and does not need treatment with additional toxic chemicals. It has inbuilt fire resistance and offers secure characteristics due to its strength and robustness, and will last for a minimum of 60 years with little or no maintenance.
There is no process of natural decay, which bodes well for future predicted environmental changes, and as a material for buildings is well regarded by designers and the public alike, who according to research, view masonry built houses as having the longest life expectancy of all construction options. Sustainability is no longer an issue of choice, but must be considered at the very heart of ongoing development for our society.
Assessing the sustainable credentials of products is a complex business and must take into consideration their combined environmental, economic and social impact and performance. As illustrated here, concrete is a fundamental building material which combined environmental, economic and social performance is strong. It therefore has a critical role to play in delivering more sustainable communities, by reducing emissions and providing long-lasting, secure as well as cost and energy efficient buildings for the future.
We in the cement and readymix concrete industries are proud of the essential role we have played in creating Britain’s built environment and are positive that our industry has a lot more to contribute in the future to the further development of sustainable building materials.
Notes to editors: CEMEX is a global building materials company and leading supplier of cement, ready-mixed concrete and aggregates. In the UK, CEMEX also has a significant share of the asphalt, concrete block and mortar markets. The company has a national supply network in the UK with over 500 locations, to ensure that quality building materials is available to customers locally. For more information, www.cemex.co.uk or www.cemex.com