Most people are aware of the significant contribution to global warming made by the worldwide cement and concrete industry. Yet the very ubiquity of concrete is indicative of the extent many more people are dependent on its capacity to provide them with a flexible cheap, and durable building material. Indeed it's unique utility could be argued as the key mitigating feature against its phasing out from the global construction.
And yet, in the developed countries at least, manufacturers of cement are endeavouring to reduce their product’s impact on the environment. In the UK particularly over the last decade, the concrete industry has moved forward with a range of initiatives that include on the one hand technical improvements to reduce global warming gases and on the other hand an educational programme aimed at engineers and building designers that pushes concrete’s sustainable credentials.
Overall CO2 emissions
Mainly through switching from coal to gas, the cement industry cites a reduction in CO2 emissions by 55% since 1990. In addition it has published a roadmap that sets out the actions that are required by the sector and Government to enable emissions of greenhouse gases to be reduced by 81% by 2050 compared with 1990 levels. More……
Material developments and emissions reduction
To date the main strategy for reducing CO2 emissions has been by replacing some of the Portland cement in a concrete mix with substitutes such as ground granulated blast furnace flag (ggbs) and fly ash (pfa). More……
There is currently a high degree of investment in producing new technologies that reduce the impact of cement production including, for example, one that uses relatively large quantities of CO2 in the production process.
Projecting the sustainability-related performance benefits of concrete
Through an extensive education programme, the concrete industry has been making building designers aware of specifying concrete in a manner conducive to sustainable construction. Key areas include:
1 Thermal mass
• In around 2002 researchers quantified the advantages in the relationship between ‘heavy’ concrete based construction and the use of thermal mass. This is likely to be useful in the future in helping to control indoor temperatures and in particular reduce the rise in instances of overheating in buildings.
• Design developments both in building design and the technology of concrete slabs has accelerated in recent years to the point where properties of concrete are routinely used in the overall calculation of thermal performance in buildings. More……
Concrete's long life means that is more likely that a concrete building will come to the end of its life because no further use can be found for it, rather than a case of the concrete having failed due to age. In these cases, demolition is not always the automatic course. Structures can often be stripped back to their concrete core, then rebuilt to new, contemporary specifications. The Concrete Centre has a number of case studies illustrating this feature.
3 Flood resiliance
Flood resilient construction uses methods and materials that reduce the impact from a flood, ensuring that structural integrity is maintained, and the drying out and cleaning required, following inundation and before reoccupation, is minimised.
• Concrete is inherently water resilient and suitable in a construction designed to be either waterproof, as required for water barriers, or water resilient.
• The extent to which the structure keeps out water depends on the specification of the concrete itself and its design details. More……