Earthern construction as a tailored alternative to conventional carbon-intensive materials in construction

Conventional, modern-day construction materials such as concrete and steel are known to result in high levels of carbon dioxide (CO2) emissions; it is estimated that the construction and processing of such materials contribute to 11% of global CO2 emissions. Earthen construction materials (ECMs) are often viewed as outdated and having inadequate mechanical properties; whilst improvements in durability are desired, ECMs have an extremely low embodied carbon. It is suggested that the widespread application of such materials can result in reduced levels of total embodied carbon, i.e., McAuliffe across all life cycle stages, from material extraction to end-of-life disposal.
I would like the principal focus of my PhD to be the improvement of ECM durability, hence increasing the feasibility of ECMs as a modern-day, mainstream construction material. Although existing earthen structures are typically single-storey buildings, the material properties can be developed to allow for applications such as contemporary architecture, highways infrastructure or land regeneration. I intend to study tailored properties of ECMs and in turn, identify the most suitable applications. I aim to carry out trials ranging from small, laboratory-sized samples to full scale. Each study shall highlight how ECM durability can be improved through the impact of various material constituents, additives, or construction techniques.
Durability and thus, longevity are key concerns with the widespread usage of ECMs. The longevity 10665199of an ECM is entirely governed by external factors, with water-induced erosion being the primary cause of failure. The effects of driving rain and high humidity levels result in unsaturated soils becoming more susceptible to erosion via hydromechanical weakening. Desired durability properties will vary with application; however, all external applications will require an improvement in water resistance. I suggest that durability against external weather conditions (investigated through abrasion resistance, freeze and thaw and water resistance), and the influence of aging (examined using accelerated aging and carbonisation techniques) are investigated further to determine how resilience can be improved.
To promote a circular economy and maintain focus on low carbon materials and construction processes, waste products can be used. Waste streams can include, but are not limited to, construction and excavation waste, food waste and industrial waste. Additives can provide specific material enhancements; the type and quantity of waste additives will be studied to ensure beneficial impacts on ECM performance. For example, the hydrophobic effect of non-toxic oils can improve water resistance whereas ground granulated blast furnace slag (a by-product of the steel industry) can be utilised to improve compressive strength and reduce shrinkage. Non-hazardous excavation waste is usually recycled for aggregates or used for on-site retaining structures. Excavation waste generally comprises ECM constituents, if the waste material is deemed suitable for earthen construction, the fine gravel and earth can be utilised as the bulk ECM components.
In order to verify the carbon benefit of proposed ECMs, the upfront and embodied carbon can be quantified through the completion of life cycle assessments.

The primary impact of the FIBE2 CDT will be the benefit to society that will accrue from the transformative effect that FIBE2 graduates will have upon current and future infrastructure. The current FIBE CDT has already demonstrated significant impact and FIBE2 will extend this substantially and with particular focus on infrastructure resilience. There will be further impacts across academic research, postgraduate teaching, industry-academia partnering and wider society. Our CDT students are excellent ambassadors and their skills and career trajectories are inspirational. Their outputs so far include >40 journal and conference papers, contributions to a CIRIA report, a book chapter and >15 prizes (e.g. Cambridge Carbon Challenge, EPSRC Doctoral Prizes, best presentation awards). Our students' outreach activities have had far reaching impacts including: Science Festival activities and engineering workshops for school girls. Our innovative CDT training approaches have shifted the culture and priorities in academia and industry towards co-creation for innovation. Our FIBE CDT features in the EPSRC document 'Building Skills for a Prosperous Nation'. Our attention to E&D has resulted in 50% female students with the inspirational ethos attracting students from wide ranging educational backgrounds.

FIBE2 CDT will build on this momentum and expand the scope and reach of our impact. We will capitalise on our major research and training initiatives and strategic collaborations within academia, industry and government to train future infrastructure leaders to address UK and global challenges and this will have direct and significant technical, economic and social impacts for UK infrastructure, its associated stakeholders and civil society at large.

As well as the creation of cohorts of highly skilled research cohorts with cross-disciplinary technical skills, further specific impacts include:

-a transformational cross-disciplinary graduate training and research approach in infrastructure with depth and breadth.

-new forms of Industry-University partnerships. Co-creation with industry of our training and research initiatives has already led to new forms of partnerships such as the I+ scheme, and FIBE2 will further extend this with the 'employer model' variant and others.

-skilled research-minded challenge-focused graduates for UK employers who will derive significant benefit from employing them as catalysts for enterprise, knowledge exchange and innovation, and thus to business growth opportunities.

-enhanced global competitiveness for industrial partners. With our extensive network of 27 industry partners from across all infrastructure sectors who will actively shape the centre with us, we will deliver significant impact and will embrace the cross-disciplinary research emergeing from the CDT to gain competitive advantage.

-support for policy makers at the highest levels of national and local government. The research outcomes and graduates will contribute to an evidence-based foundation for improved decision-making for the efficient management, maintenance and design of infrastructure.

-world-class research outcomes that address national needs, via the direct engagement of our key industrial partners. Other academic institutions will benefit from working with the Centre to collectively advance knowledge.

-wider professional engagement via the creation of powerful informal professional networks between researchers, practitioners, CDT alumni and CDT students, working nationally and internationally, including some hosted by FIBE2 CDT industry partners.

-future generations of infrastructure professional inspired by the FIBE2 CDT's outreach activities whereby pupils, teachers and parents gain insight into the importance of infrastructure engineering.

-the generation of public awareness of the importance of a resilient infrastructure to address inevitable and often unexpected challenges.