More frequent intense rainfall events, associated with climate change, increase the likelihood of shallow slope failures that lead to costly disruption of road and rail journeys, with risk to life and property. There have been recent slope failures adjacent to transport corridors in the UK, sometimes disrupting important road and rail routes for days. Vegetation has a stabilising effect on slopes: Plant root systems interlock with the soil, increasing its stiffness and strength. Uptake of water by root systems dries the soil profile, again increasing soil stiffness and strength. However, engineers need to be able to predict the combined root reinforcement and soil drying effects on slope stability, so that vegetation management can be used proactively to decrease the probability of slope failure. Vegetation has numerous benefits over conventional hard-engineering solutions, in terms of burying carbon in the soil, enhancing biodiversity, and improving the aesthetic quality of the environment for society. This project will develop and test a quantitative coupled hydro-mechanical model for the in-service and ultimate-failure performance of slopes planted with vegetation. Rooted-soil represents an innovative sustainable construction material, with distinct mechanical and hydrological properties, that can be used in geotechnical systems. The model will be applicable to both slopes covered with natural vegetation and slopes where vegetation and soil have been chosen and managed according to engineering principles. The validated model will provide a clear framework for assessment and remediation of slopes with potential for reducing economic and carbon costs. The model will be developed within a multi-scale continuum modelling framework. It will build on knowledge of the elemental components of the system, working from individual soil-root interaction, to continuum soil-root system, and to complete slope, incorporating spatial variability of materials. Modelling will be informed by X-ray CT imaging of the 3-D deformation of rooted soil undergoing shear, using the micro-VIS facility at the University of Southampton, and by field data from slopes containing established vegetation. Predictions of slope performance will be validated against scaled-slopes in the Dundee geotechnical centrifuge under different rainfall regimes. The geotechnical centrifuge enables the testing and monitoring of small-scale slopes containing roots at realistic stresses, which can be manipulated until the slopes ultimately fail. Template guidelines will be produced for a manual of combinations of plant species, soils and management schemes for optimum performance of designed soil-plant systems suited to emerging climatic conditions. Example data will also be included to allow cost-benefit analyses when designing for slope improvement using vegetation. The potential to translate research findings into related areas will be investigated (e.g. river banks, sand dunes, flood embankments, agricultural and amenity systems). We will engage with an important group of Project Partners, representing key industrial sectors and infrastructure owners, to facilitate the rapid adoption of research findings.

The increasing demand for low and zero carbon buildings in the UK has provided significant challenges for the energy intensive materials we currently rely on. At present somewhere between 20% and as much as 60% of the carbon footprint of new buildings is attributable to the materials used in construction; this is predicted to rise to over 95% by 2020. If the UK is to meet agreed 80% carbon reduction targets by 2050 it is clear that significant reductions in the embodied carbon of construction materials is required. What also seems clear is that current materials and systems are not capable of delivering these savings. The drive for an 80% reduction in carbon emissions, a decreasing reliance on non-renewal resources and for greater resource efficiency, requires step changes in attitude and approach as well as materials. Improvement in construction systems, capable of providing consistently enhanced levels of performance at a reasonable cost is required. Modern developments in construction materials include: eco-cements and concretes (low carbon binders); various bio-based materials including engineered timber, hemp-lime and insulation products; straw based products; high strength bio-composites; unfired clay products utilising organic stabilisers; environmentally responsive cladding materials; self healing materials; smart materials and proactive monitoring; hygrothermal and phase change materials; coatings for infection control; ultra thin thermally efficient coatings (using nano fillers); ultra high performance concretes; greater use of wastes; and, fibre reinforcement of soils. However, very few of these innovations make the break through to widespread mainstream use and even fewer offer the necessary step change in carbon reductions required A low carbon approach also requires novel solutions to address: whole life costing; end of life (disassembly and reuse); greater use of prefabrication; better life predictions and longer design life; lower waste; improved quality; planned renewal; and greater automation in the construction process. As well as performance, risk from uncertainty and potentially higher costs other important barriers to innovation include: lack of information/demo projects; changing site practices and opposition from commercial competitors offering potentially cheaper solutions.. A recent EPSRC Review has recognised the need for greater innovation in novel materials and novel uses of materials in the built environment. The vision for our network, LIMES.NET, is to create an international multi-disciplinary community of leading researchers, industrialists, policy makers and other stakeholders who share a common vision for the development and adoption of innovative low impact materials and solutions to deliver a more sustainable built environment in the 21st Century. The scope of LIMES.NET will include: adaptive and durable materials and solutions with significantly reduced embodied carbon and energy, based upon sustainable and appropriate use of resources; solutions for retrofitting applications to reduce performance carbon emissions of existing buildings and to minimise waste; climate change resilient and adaptive materials and technologies for retrofitting and new build applications to provide long term sustainable solutions. In recognition of their current adverse impacts and potential for future beneficial impacts, LIMES.NET will focus on bringing together experts to develop pathways to solutions using: renewable (timber and other plant based) construction materials; low-impact geo-based structural materials; cement and concrete based materials; innovative nano-materials and fibre reinforced composites. Through workshops and international visits the network will create a roadmap for multidisciplinary research and development pathways that will lead to high quality large research proposals, and an on-going virtual on-line centre of excellence.