Bacteria benefits for concrete carbon

A joint project between the University of East London and a cement company has developed a self-fixing concrete that uses bacteria to repair itself. The new material is expected to reduce corrosion in locations like sea walls, and could also reduce carbon emissions by concrete manufacturers. 

UEL worked with JP Concrete (JPC) to come up with the bio-concrete, which has three novel features. Traditional concrete manufacturing requires high temperatures, which contribute to global warming but in the new product, less cement is needed as some of it is replaced by recycled powder from metal manufacturing. Less cement means less heat is required and so less carbon is produced. 

In addition, bacteria were added to the concrete mix to fill cracks. Concrete is a brittle material, which cracks over time but once activated the bacteria in the mix produces limestone which fills any gaps or flaws in the material. The key innovation in this study was to also add a corrosion inhibitor to the mix in order to seal steel bars used to reinforce concrete. This can help extend the service life of infrastructure exposed to harsh environments like coastal defences, retaining walls, tunnels, culverts, and below ground structures. The research team at UEL carried out an extensive experimental investigation to examine the combined effect of self-healing and corrosion-inhibiting admixtures. As a result, an innovative low-carbon concrete mix was proposed that enables the self-healing of cracks and protects steel bars, creating a sustainable resilient concrete solution.

The experimental testing of the new bio-concrete mixes took place at the University’s concrete materials and structures testing facilities, part of UEL’s civil engineering laboratories, with the research team led by Prof David Tann and Dr Ali Abbas. Dr Abbas said he had long considered a bacteria/concrete mix,

The idea of using bacteria to heal concrete cracks has always fascinated me. It brings a human feel to a material otherwise conceived as hard and lifeless.” 

The joint UEL/JPC was undertaken as an Accelerated Knowledge Transfer to Innovate (AKT2I) partnership, funded by the UK government’s innovation agency, Innovate UK, which aims to encourage dynamic collaborations between the business and academic worlds. 

Phil Sayers, Director of JP Concrete, commented “We are extremely pleased with the outcomes from the AKT2I research into corrosion inhibitors in concrete. Dr Abbas and the team have delivered another fantastic project and the findings will be extremely valuable in developing more resilient precast concrete products in the future.” 

The company provided all the materials and admixtures required, while factory managers, innovation, and marketing managers from JP Concrete were also involved in the partnership. 

The AKT2I partners estimate that the automatic healing of cracks and corrosion protection will save 15 to 20 percent of total maintenance costs for concrete structures in harsh environments, with the longer lifespans of such structures also contributing towards net zero carbon targets. Dr Abbas said his team was particularly interested in products with environmental benefits, “Low-carbon and resilient concrete products are needed so that more durable and long-lasting structures can be built to meet the needs of future generations and our UEL research team is working hard to make its contribution.”   

The search for “greener concrete” is particularly important because the industry is a major emitter of carbon. It is estimated that if the worldwide cement industry were a country, it would be the third largest carbon dioxide emitter in the world, producing up to 2.8 billion tonnes, surpassed only by China and the United States.