Researcher Spotlight: How concrete is being reimagined

IFM Research Fellow Dr Alastair MacLeod

For some people concrete is considered mundane, but for research fellow Dr Alastair MacLeod concrete has endless potential.

Dr MacLeod joined the Institute for Frontier Materials in 2016. His specialty is the study of advanced cement and concrete composite materials with enhanced strength, increased durability and multi-functional characteristics.

“I am a civil engineer by training and I have been conducting research into cementitious materials for the past 10 years,” Dr Macleod says.

“I began with a PhD at Monash University, where I investigated the microstructural and durability effects of the addition of carbon nanotubes into cement.

“Since joining Deakin in 2016, I’ve had the opportunity to extend the work I began during my PhD, studying the effects of carbon nanotubes on the mechanical, electrical, microstructural and fluid properties of concrete. This work was part of an ARC Linkage Project with Eden Innovations, under the research leadership of chief investigator Professor Frank Collins.

“Our research facilitated the development of a product for enhanced concrete performance that is now sold in construction materials markets worldwide.”

Dr MacLeod is active within the industry with professional memberships with Engineers Australia; Australasian Corrosion Association; and the Concrete Institute of Australia. He is a RILEM (International Union of Laboratories and Experts in Construction Materials, Systems and Structures) Young Member and a RILEM Technical committee member for CNC: Carbon-based nanomaterials for multifunctional cementitious matrices. He was also a conference organiser for the Concrete Institute of Australia’s Concrete 2019 biennial conference in Sydney.

Dr MacLeod was also engaged by the trust overseeing the iconic and World Heritage Listed Sydney Opera House for its concrete rehabilitation and durability assessments, which he considers a career highlight.

The current research he is working on is showing exciting potential. Dubbed “electrocrete” the team, made up of Dr MacLeod, Associate Professor Will Gates, PhD student Carlos Zapata, Dr Andras Fehervari and Professor Frank Collins, are working towards a practicable, scalable implementation of a thermoelectric concrete material with real-world potential applications. The technology could be used as a new source of supplemental renewable energy, by harvesting electrical energy generated from thermal gradients found in buildings.

“This is the first time that laboratory-scale specimens, under realistic thermal gradient loading, could currently – in principle – be used to power structural health monitoring sensors,” MacLeod says.

“Our work is demonstrating – for the first time – that a practicable, affordable and scalable ‘electrocrete’ is possible.”

What is your current focus?

Alongside the investigation of the effects of a nano-sized additive for enhancing the strength and durability of concrete, I (somewhat serendipitously) had been developing an interest in multi-functional cementitious materials – that is, structural construction materials with added capabilities; for example: self- sensing, self-healing, or energy storage and harvesting.

I was intrigued by the possibilities of a sustainable, passive energy-harvesting concrete material that exploits thermal gradients to harvest otherwise wasted heat energy present in buildings, roads, foundations and other structures. Preliminary experiments showed significant promise, particularly in comparison to the sparse prior studies in this area, which led to the development of our current research program.

Our aim is to develop a specially modified, multifunctional structural concrete that can harvest usable quantities of electrical energy from the low temperature gradients (< 30°C) present in the environment. The harvested electrical energy can then be dispatched for any desired purpose, from powering sensors, to localised battery storage, or potentially municipal lighting or grid feed-in requirements.

This material will be: (i) readily adaptable to existing construction practice; (ii) economical, using relatively plentiful additive materials; and (iii) maintain structural performance characteristics of the construction material. It will require no significant changes in concrete technology but will require engagement with architects and adaptation by engineers in the planning stages for greatest effect.

What makes you passionate about this area?

Concrete is the single most widely used (mass and volume) man-made material on the planet. It has a long history (ancient China and the Roman Empire used pozzolanic versions) of application since the discovery of calcium hydroxide and lime mortar in prehistory. I hope to ultimately develop new materials that bring the seemingly mundane material of concrete into the 21st Century as an integral part of the built environment.

What has driven you to research in this area?

My research interests include: strength and durability enhancement and characterisation of nano-modified cementitious materials; multi-functionality – self-sensing and electrical characteristics, including energy storage – of nano-modified cementitious materials; and the use of novel supplementary cementitious materials to reduce the embodied carbon of cement and concrete materials.

As an engineer, I’ve always wanted to improve the situation of society by contributing to solving (in what little way I am able) some of the grand and important challenges of our time – anthropogenic climatic change, energy scarcity, sustainable and durable structures and cities. My expertise in enhancing the strength, durability and multi-functionality of concrete – the most ubiquitous and mundane of materials – has inexorably led me towards developing intriguing and novel solutions that may one day be used to help address a small fraction of these problems: lower embodied carbon concretes and longer-lasting infrastructure to help tackle climate change; “electrocrete” to provide a new way to generate electricity, potentially at a large scale; and stronger, more economical and longer-lasting structures to help make our built environment more sustainable and last for generations to come.

Learn more about our Infrastructure Materials Group.