Low Carbon Concrete: Durability and Performance

Academic Institution: University of Dundee

Academic Supervisor: Professor Rod Jones

Industry Partner: Mineral Products Association (MPA) and British Ready-mixed Concrete Association (BRMCA)

PhD Student: Maciej Jozwik

Start Date: 1st July 2020

Abstract

It is well established that concrete is used in very large quantities worldwide and will be difficult to supersede. In response to climate change issues a ‘route map to 2050’ for new low carbon concrete has been established globally and this will require replacing up to 60% of Portland cement clinker with combinations of limestone, fly ash and/or slag. In the UK alone, this has the potential to reduce CO2 emissions by up to 4 mt/yr.

However, whole-scale adoption of these new generations of low carbon concretes will not be straightforward, as there are key industry-identified concerns over long-term durability and fire performance namely (i) carbonation and chloride ingress, (ii) reinforcement passivity and initiation and propagation of corrosion of rebar and (iii) response to fire.

Assessing the durability of low carbon concrete containing ‘slower’ reacting cements requires the ability to carry out tests quickly and fairly and identify optimal combinations of constituent materials. However, current durability test exposure periods are far too long for industry to do this (typically 4-12 mths). Furthermore, there are considerable polarised scientific and technical disagreements with regard the effects of accelerating exposure environments.

Of equal importance are the effects of changes in hydrate chemistry and microstructure, due to the use of low carbon cement combinations on performance in fires. To date these have not been quantified and, in a post-Grenfell era, there is an urgent need to establish the behaviour of low carbon concrete in fire conditions.

These are complex problems that require careful and considered scientific and technical understanding at a fundamental level, and will certainly require interdisciplinary skills to be exercised. Bringing expertise from Dundee, Aberdeen and Edinburgh together will allow the project to optimise and define the performance of low carbon concrete.