Dubai has taken a giant step forward in greening up the city with its decision to move away from ordinary Portland cement (OPC) for all new buildings. As of April 1, OPC use is limited across the emirate; building permissions are reliant on developers specifying eco-friendly Supplementary Cementing Materials (SCMs). The new requirement aims to give residents a clean and pollution-free environment.
Portland cement is a basic ingredient in concrete, stucco, mortar, and most non-specialty grout. It’s manufactured by super-heating a mix of chalk or limestone with clay to produce a material called clinker, which is then mixed with gypsum and pulverized to form OPC. There are significant environmental problems related to OPC manufacture, transport and usage:
- Quarrying the raw materials permanently scars the natural landscape.
- Producing one tonne of clinker requires large amounts of energy (typically coal or petroleum coke) and emits one tonne of carbon dioxide (CO2), plus toxic gases, and pollutants such as nitrogen and sulfur oxides (NOx and SOx).
- That tonne of new cement also generates 164 kg of dust, which intensifies global warming and causes increased chance of disease such as asthma and cancer for workers and nearby residents.
- Transporting OPC to mixing plants and job sites produces dust and noise and consumes fossil fuels.
DM’s decision to mandate use of OPC substitutes – recyclable byproducts from other industries such as fly ash and ground granulated blast slag (GGBS) – follows extensive research on the risks associated with OPC and the feasibility of safer alternatives, officials said at a press conference last Sunday.
“We are keen to provide what is best for the city. We are looking at every element of buildings,” DM Director-General Hussain Nasser Lootah told the Khaleej Times.
The construction industry is ready to switch to green concrete, according to Robin Styles, technical support manager of CEMEX, a global leader in building materials.
“From the ready-mix industry perspective, I think we are very well prepared for the change…The municipality has been engaging with the stakeholders for a few years. By using these alternative options, you can reduce the carbon footprint of concrete by up to 45 per cent,” he said.
The UAE construction industry depends on a dozen in-country cement manufacturers, presently producing about half the tonnage that they are capable of. These factories will now increase fly ash and GGBS output.
Green building materials can cut the carbon footprint of a structure by up to 45 percent compared to a similar structure built from traditional concrete and often offer better quality at the competitive prices. The green additives create a stronger concrete mix, more resistant to water, salt and sulfate than OP, and causing less dust and fumes. The result is more durable buildings.
“Building a sustainable city includes all aspects that impact society, economy and environment,” said Lootah, “The concept of Green Buildings will enhance the level of Dubai among sustainable cities. The 79 regulations will deal with the buildings from its designing stage by choosing sustainable sites, using appropriate orientation and using modern techniques which help in minimizing the environmental impacts of construction phase in balance with economic vision. The regulations and specifications support green products and materials used in construction and operation processes.”
DM introduced Green Buildings Regulations in 2010 to improve building performance, to enhance a healthy indoor life style, and cut use of natural resources over project lifetime. Initially mandatory for government projects only, as of March 2014 all projects must completely abide by the green building regulations.
Dubai has ambitions to be one of the top ten sustainable cities in the world by 2020.
Image of concrete wall from Shutterstock