Low-Carbon Multi-component Marine Cementitious Materials for Sustainable and Resilient Infrastructure

Project Information

LCMMCMs

Grant agreement ID: 101199069

DOI

10.3030/101199069

Project terminated on 31 December 2025

EC signature date 10 April 2025

Start date 1 August 2025

End date 31 July 2027

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 260 347,92

Coordinated by

BRUNEL UNIVERSITY LONDON
United Kingdom

Periodic Reporting for period 1 - LCMMCMs (Low-Carbon Multi-component Marine Cementitious Materials for Sustainable and Resilient Infrastructure)

Reporting period: 2025-08-01 to 2027-07-31

Summary of the context and overall objectives of the project

Concrete is the world’s most widely used construction material, yet its production is responsible for 5-8% of global CO2 emissions, mainly due to clinker manufacture. With more than 4 billion tonnes of cement produced annually, the sector emits approximately 2.7 billion tonnes of CO2 per year, making it a major barrier to achieving the Paris Agreement target of limiting global temperature rise to well below 2 °C. These challenges are even more critical for marine infrastructures, where sustainability and durability issues converge. Coastal and offshore structures suffer from severe chemical attack, microstructural deterioration and accelerated corrosion due to chloride-, sulphate- and magnesium-rich environments. Meanwhile, freshwater and natural aggregates-traditionally required for concrete-are scarce on islands and many coastal regions, especially in Europe where nearly half the population lives within 50 km of the sea. To reduce environmental pressure while supporting Europe’s extensive maritime infrastructure, there is growing interest in using seawater and industrial by-product supplementary cementitious materials (SCMs) to produce low-carbon concrete. Early studies suggest that seawater ions can accelerate hydration of silicate and aluminate phases, while SCMs improve long-term durability and reduce clinker demand. However, the combined chemo-physical effects of seawater ions and SCMs remain poorly understood, limiting safe and widespread adoption. Furthermore, without a durability-integrated life-cycle assessment (LCA), industry and policymakers lack the evidence needed to implement such materials in design standards and coastal construction.
The LCMMCMs project aims to develop Low-Carbon Multi-Component Marine Cementitious Materials with high durability and reduced environmental footprint for coastal and offshore infrastructure. The project’s scientific and technological objectives are:
(1) Unravel the ion-specific effects of seawater on hydration and structural evolution of cement components.
(2) Quantify and optimise the synergistic interactions between seawater ions and SCMs, enabling tailor-made, high-performance marine binders.
(3) Determine the mechanical performance and long-term durability of LCMMCMs under realistic marine exposure.
(4) Develop a durability-coupled LCA model to assess environmental and economic impacts throughout their service life.
(5) Train the Fellow as an independent leader in sustainable marine construction materials through a multidisciplinary programme integrating experiments, simulations, engineering and industry applications.
Together, these objectives address four scientific challenges: ion-dependent hydration (SC1), seawater-SCM interactions (SC2), long-term service performance (SC3) and life-cycle sustainability (SC4).

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the project, a comprehensive programme of multiscale experiments, characterisation techniques and atomistic simulations was conducted to elucidate the chemo-physical mechanisms governing seawater-mixed cementitious materials. The work focused on understanding ion-specific effects during hydration, optimising synergistic interactions between seawater ions and SCMs, and identifying durability mechanisms essential for long-term marine performance.
(1) Hydration behaviour of cement components in seawater: A series of ingeniously designed experiments and molecular simulations was carried out to unravel the complex hydration reactions of tricalcium silicate (C3S) in chloride-containing environments representative of seawater. C3S pastes were hydrated in solutions with varying chloride concentrations and with controlled additions of Ca²⁺, Mg²⁺ and alumina nanoparticles (ANPs). Advanced characterisation tools—including in-situ XRD, Raman spectroscopy, TEM/SEM-EDS, TGA and NMR—were deployed to quantify dissolution rates, phase assemblages and the evolution of hydrates. The results reveal distinct chloride binding mechanisms regulated by the solution chemistry. The presence of Ca²⁺ and Mg²⁺ ions significantly alters the surface charge distribution of hydration products, enhancing their affinity for chloride ions. ANPs further promote the formation of calcium-(alumino)silicate hydrates (C-(A-)S-H), accelerating nucleation and modifying their nanostructure and surface reactivity.
(2) Molecular insights into seawater–hydrate interactions: To complement experimental observations, extensive ab-initio molecular dynamics (AIMD) and charge distribution analyses were conducted. These simulations provide mechanistic insights into the coordination environment, electronic structure and adsorption energetics of chloride at C-(A-)S-H interfaces. The calculations demonstrate that Ca²⁺ and Mg²⁺ ions act as electronic linkages bridging surface oxygen sites and adsorbed chloride ions. This stabilises chloride binding and reduces repulsive interactions at the interface. The introduction of Al into the silicate chains—representing SCM-derived alumina incorporation—creates localised negative charge pockets that intensify the binding affinity for chloride. Stable Al–O–M (M = Ca or Mg) linkages form, amplifying chloride capture and explaining the experimentally observed improvements in binding capacity.
(3) Implications for durability and sustainable material design: The work establishes a mechanistic foundation for designing high-durability, seawater-mixed multi-component cementitious materials. Enhanced chloride binding, modified surface chemistry, and improved C-(A-)S-H stability directly translate to reduced steel corrosion risk and prolonged service life of marine concrete.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The LCMMCMs project delivers results that significantly advance the state of the art in seawater-mixed, low-carbon cementitious materials by providing the first integrated mechanistic understanding of how seawater ions and alumina species synergistically regulate hydration, microstructure and chloride binding in C-(A-)S-H. Through combined advanced experiments and ab-initio simulations, the project uncovers ion-specific chloride binding pathways that depend on Ca²⁺ and Mg²⁺ concentrations and demonstrates that alumina substitution and ANPs introduce negatively charged Al–O–M linkages that markedly enhance chloride capture—mechanisms not previously identified in marine concrete research. These findings establish a new conceptual framework linking ionic environment, nanoscale hydrate chemistry and macroscopic durability, enabling rational design of seawater-mixed binders beyond empirical approaches. The project provides quantitative relationships between ionic composition, hydrate nanostructure and performance, offering new design principles for SCM-rich, low-clinker formulations with improved service life and reduced carbon footprint. These advances have strong potential impacts on marine infrastructure durability, decarbonisation of the cement sector and resource efficiency, while paving the way for future large-scale demonstration, industrial uptake, regulatory integration, and performance-based standardisation of seawater-mixed concrete across Europe.

Photograph illustrating and promoting the work of the project