Graphene–Concrete Composites for Multifunctional Applications

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Advanced Functional Materials,Volume 28, Issue 23

Abstract

There is a constant drive for development of ultrahigh performance multifunctional construction materials by the modern engineering technologies. These materials have to exhibit enhanced durability and mechanical performance, and have to incorporate functionalities that satisfy multiple uses in order to be suitable for future emerging structural applications.

There is a wide consensus in the research community that concrete, the most used construction material worldwide, has to be engineered at the nanoscale, where its chemical and physiomechanical properties can be truly enhanced.

Here, an innovative multifunctional nanoengineered concrete showing an unprecedented range of enhanced properties when compared to standard concrete, is reported. These include an increase of up to 146% in the compressive and 79.5% in the flexural strength, whilst at the same time an enhanced electrical and thermal performance is found. A surprising decrease in water permeability by nearly 400% compared to normal concrete makes this novel composite material ideally suitable for constructions in areas subject to flooding.

The unprecedented gamut of functionalities that are reported in this paper are produced by the addition of water‐stabilized graphene dispersions, an advancement in the emerging field of nanoengineered concrete which can be readily applied in a more sustainable construction industry.

Introduction

The new global standards of modern civil technologies, continuously requiring more demanding infrastructure, are driving the development of ultrahigh performance multifunctional construction materials. In particular, extensive efforts are focused on increasing the performance and functionality of concrete, the most used construction material worldwide. A truly step changing approach to enhance mechanical performance and to provide novel functionalities requires intervention at the nanoscale since most of the damage caused to concrete can be traced back to chemical and mechanical defects in the cement structure.

Current research efforts are therefore directed at exploring new ways of enhancing the performance of concrete by nanoengineering the chemical and physico‐mechanical properties of cement, the main binding element in the composition of concrete. The cement particles, which consist of a variety of chemical elements (such as calcium silicates, aluminates, and aluminoferrites), undergo transformation from powder form to fibrous crystals upon reacting with water, known as the hydration reaction. Their growth and mechanical interlocking over time are the most significant factors in shaping the material properties of concrete.

The outstanding chemical and physical properties of nanomaterials provide the most efficient enhancement for the internal matrix of concrete, and recent progress in nanomodification of cement composite materials has enabled applications in structural reinforcement, reduction of environmental pollution, and production of self‐cleaning materials.

Previous studies have largely focused on the incorporation of nanomaterials in cement. These include the incorporation of carbon nanotubes (CNTs) and graphene oxide (GO)in cement which resulted in a 50% (for CNT) and a 33% (for GO) improvement of the compressive strength, while industrial‐grade thin graphite platelets (100 nm thickness) were shown to improve the thermal conductivity. However, these findings do not extend directly to concrete, as the addition of sand and aggregate changes the physico‐mechanical behavior of the material. Moreover, to date the role of atomically thin materials on nanoengineering of concrete is yet to be explored, and this holds the promise to change the landscape of construction materials leading to a more sustainable urbanization with lower carbon foot print and more resilient constructions against natural disasters.

Here we report innovative few‐atoms‐thin graphene‐enabled nanoengineered multifunctional concrete composites which display an unprecedented range of enhanced properties compared to standard concrete. We demonstrate an extraordinary increase of up to 146% in the compressive strength, up to 79.5% in the flexural one, and a decrease in the maximum displacement due to compressive loading by 78%. At the same time, we find an enhanced electrical and thermal performance with 88% increase in heat capacity.

A remarkable decrease in water permeability by nearly 400% compared to the standard concrete, which is an extremely sought‐after property for long durability of concrete structures, makes this novel composite material ideally suitable for constructions in areas subject to flooding.

Finally, we show that the inclusion of graphene in nowadays concrete would lead to a reduction by 50% of the required concrete material while still fulfilling the specifications for the loading of buildings. This would lead to a significant reduction of 446 kg per tonne of the carbon emissions by the cement manufacturing.

Crucially, we demonstrate that the unprecedented gamut of functionalities that we report in this paper are produced by the addition of water‐stabilized graphene dispersions, with high yield, low cost, and compatible with the large‐scale manufacturing required for the use of this material in practical applications. The unprecedented range of functionalities and properties uncovered in our study represents an advancement in the emerging field of nanoengineered materials which can be readily applied in a more sustainable, environmentally friendly construction industry.

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