Cement is the ‘glue’ in concrete, the foundation upon which our modern civilisation is built. However, this comes with a huge environmental cost - cement production generates 8% of global CO2 emissions, and half of all materials extracted from Earth are used in concrete.

Luckily, recently developed low-carbon alkali-activated cements that we are investigating exhibit enhanced properties (e.g. strength and durability) and reduce CO2 emissions by >80%, compared to traditional Portland cement (PC), and are made almost entirely from industrial wastes.

These cements require superplasticising copolymer dispersants to improve workability and flow characteristics, particularly for ultra-high performance concrete. However, dispersant behaviour differs significantly in each case due to extensive differences between aqueous and solid state chemistry in these cements, compared to PC. New alkali-resistant high-performance dispersants are urgently required for these next-generation low-carbon cements to make them practical for use in large-scale construction applications.

In this PhD project we will examine the interactions between organic superplasticisers and inorganic cement particles in these next-generation low-carbon alkali-activated cements, and then use this knowledge to design novel superplasticisers with enhanced performance. We will adopt a new in situ characterisation approach (including surface-specific techniques and both spectroscopic and microstructural characterisation) to investigate the mechanisms and kinetics of organic-inorganic interactions, and their effects on cement performance.

This study will link raw materials characteristics (particle size/distribution, morphology, surface area/chemistry, superplasticiser structure, molecular weight) with processes controlling dispersion and fluidisation, reaction, and physical property development. 

Specifically, it will examine how interactions between organic superplasticisers and inorganic cement particles affect:

• dispersion and fluidisation

• reaction and setting

• physical property development

Data from these low-carbon alkali-activated cements will be benchmarked against data from PC-based cements. We will discover the fundamental processes controlling dispersion, fluidisation and reaction of these next-generation low-carbon alkali-activated cements, and use this knowledge to design, synthesise and test novel superplasticisers with enhanced performance. This will drive implementation and a circular economy, help decarbonise cement production, and help give humanity the best possible chance of mitigating climate change.

Check out this Grantham Centre to learn more: 

https://www.sheffield.ac.uk/energy/news/exciting-phd-projects underway-thanks-energy-institute-studentships