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Concrete Infrastructure Research Group (CIRG)

 

Mar Giménez Fernández, Dr Andre Brault, Dr Giacomo Torelli, Professor Janet Lees

 Introduction

Concrete is the most widely used material in the world. Cement, the key constituent of concrete, is responsible for about 5% of global carbon emissions related to human activities. This makes the current use of concrete particularly hazardous for the environment. Hence, it is vital to develop technologies aimed at minimising the use of cement in concrete structures while preserving, or improving, their innate strength and durability properties.

In this context, the concept of tailored reinforced infrastructure represents a promising approach to target specific structural performance while employing less cement. The design of tailored, or functionally graded, concrete infrastructure is based on the idea of grading material composition through structural elements in order to achieve multiple objectives. In other words, material with high cement content is used rationally only when it contributes significantly to the overall performance of the structure. One major challenge in the design of tailored reinforced infrastructure is to understand the effects of geometry and main mix design parameters on strength and durability properties of the hardened structure. This entails a deep understanding of the complex relationships between design variables and specific structural properties as well as a comprehensive analysis of the trade-offs. A further concurrent challenge is to design geometry and concrete mixes in light of the desired fresh state behaviour of the structure. This encompasses an in-depth analysis of the relationships between geometry, rheological properties of the candidate mixes and fresh state stability of the system.

           Tailored infrastructure schematic 2

Aims and objectives

The fundamental aim of this research is to contribute to the reduction of carbon emissions by developing robust and reliable methods for the design, construction and assessment of tailored reinforced infrastructure. Specifically, the main objectives of the research are:

  • To minimise the cement content of concrete while preserving its strength, durability and thermal mass properties at a material level.
  • To optimise the design of tailored reinforced structures as structural elements by studying the interconnections between design parameters, fresh state behaviour and hardened state performance of functionally graded systems.
  • To translate generated theoretical and technical advancements into real-life industrial applications in order to address engineering sustainability priorities for lifetime extension, lifetime costs reduction and energy minimisation.

Research directions

The research involves development, employment and cross-validation of advanced experimental, numerical and analytical techniques to address the problem of cement minimisation at both a material and a structural level.

Experiments on small-scale specimens are extending the existing knowledge on the relationships between hardened state properties of concrete and mix proportions in terms of content of cement, water, fine and coarse aggregate. This allows mechanical, thermal, and permeability properties of the material to be interpreted in light of the microstructure of the material. Furthermore, it provides key validation of the existing analytical and numerical predictive tools. Large-scale test, numerical and simplified analytical studies are being undertaken on tailored concrete structures in order to identify the main parameters affecting the fresh state behaviour and the hardened state properties of such structures. The combination of studies performed at different scales will provide the necessary knowledge to formulate a robust framework for the design and construction of functionally graded structures. 

 

Tailor experiment           IMG 0264

 

Collaborators

This project is funded by the UK Engineering and Physical Science Research Council (EPSRC). Industry collaborators on this work are Costain, Laing O'Rourke LTD and Skidmore, Owings & Merrill LLP.

Publications

Torelli G, Lees JM. (2019) Fresh state stability of vertical layers of concrete. Cement and Concrete Research, 120, 227-243. https://doi.org/10.1016/j.cemconres.2019.03.006