Firms pledge to clean up construction with green net-zero concrete

The author is Adam Vaughan.

An alliance of construction and property giants wants to encourage the development of green concrete by promising to buy only concrete with net-zero carbon emissions by midcentury.

Concrete is responsible for 8 percent of global CO2 emissions. Cement emissions have doubled in the last 20 years.

A group of 17 companies have formed a coalition to increase the use of low emission concrete by half by the year 2030. Only net-zero concrete will be used by the year 2050. The group is modeled on previous initiatives for renewables and green steel to show there is demand for lower carbon options.

Concrete is a big part of emissions. We want to put a big collective demand signal there that will give confidence to investors. The Climate Group is the non-profit organisation that has organised the campaign.

There are no solutions for the problem of decarbonising concrete. The process of making cement uses a lot of fossil fuel heat. Researchers and companies are making progress, such as increasing the strength of the material by using Graphene, so less concrete is needed to build a structure.

Read more: Steel and concrete are climate change’s hard problem. Can we solve it?

The carbon released when limestone is heated and crushed to make cement is captured and stored. There will be a role for carbon capture and storage, but it won't be huge. It comes into that sort of wand, 'don't worry, we'll wave a magic' sort of category.

In the short term, people are looking to cut concrete emissions by using fly ash, a by-product of coal power stations, as a replacement for some of the cement in the concrete. Innovations are needed because fly ash deposits are finite. He says volcanic ash can be used as an alternative to fly ash. He thinks that design choices that use less of the material could help offset the cost of low-carbon concrete.

One of the most widely used types of cement is Ordinary Portland Cement. The initiative to lower emissions from concrete is a good idea in general, but he thinks focusing on carbon capture and storage to decarbonise the cement may be more sensible.

There is no universally accepted standard for what net- zero concrete means. She hopes the new initiative will lead to alliances in China and India, where demand for concrete is high.