Professor Abir Al-Tabbaa and Dr Janet Lees from the Department of Engineering and Dr Yun Bai from Civil Engineering at University College London (UCL) have been successful in the first ever EPSRC/NSFC call for a collaborative UK/China research project on Sustainable Materials for Infrastructure.
Together with their collaborators, Professor Jueshi Qian from Chongqing University (academic visitor in 2009/10) and Professor Liwu Mo from Nanjing Tech University (RAEng Fellowship Exchange with China Scheme in 2012/13), they will lead global efforts to develop magnesia-bearing construction materials for future energy infrastructure. The project named 'MagMats' (with a budget of GBP 1M from EPSRC and NSFC) also includes collaborators from international academic centres: University of Toronto (Canada), Federal University of Minas Gerais (Brazil) and NTU (Singapore); a number of UK and Chinese industry partners: Laing O’Rourke, Shell, Lafarge Group, China Three Gorges Corporation, Yunnan Institute of Building Materials and China Energy Conservation DADI as well as global magnesia producers: Premier Magnesia, Lehmann & Voss, Magnesita and Silver Peak Haicheng Magnesium Products Co.
The objective of the MagMats project is to integrate the unique and complementary expertise within the team to collectively address major material-related challenges facing future energy infrastructure. The focus will be on performance, durability and low carbon footprint. The development of a suite of magnesia-bearing construction materials compositions for the different anticipated challenges and scenarios will be a key deliverable.
By 2020, both the UK and China plan to produce 15% of their primary energy mix from renewables, with both oil and gas and nuclear power continuing to play a major part in their future energy security. As the world’s second highest energy consumer and largest source of carbon emissions, China’s resulting environmental crisis (air pollution and devastation in land and resources) is one of the most pressing challenges to emerge: costing the country 3.5% of gross national income with life expectancy decreasing by 5 years in some regions. Nuclear and wind power have been proposed as clean energy sources for both China and the UK, while hydropower will also be a major player in China.
Many infrastructure-related material challenges have emerged as a result of the need to explore offshore marine environments for wind power generation; for deeper and more complex underground wellbore systems for new oil & gas explorations; for robust containment and shielding structures for new nuclear power plants and for larger dam structures for future hydropower generation. Specific challenges include: thermal crack prevention in mass concrete used in super-large dam structures and nuclear shielding structures to guarantee structural integrity and safety; durable performance in aggressive marine environments for deeper water off-shore platforms and wind-farm foundations; long-term and safe encapsulation systems for the increasing radioactive wastes produced in nuclear power plants; durable and designable performance in increasingly aggressive environments (higher temperatures, pressures, chloride and sulfate attack) and more complex constrained zonal isolation conditions for deeper oil and gas exploitations. Addressing these challenges requires a fundamental revaluation of the most appropriate construction materials for energy infrastructure.
The last two decades have witnessed an increasingly significant international interest in the development and applications of magnesia-bearing minerals and cements. This is fuelled by a number of factors such as the increased demands for alternative cements to Portland cement (PC) with enhanced durability and reduced environmental impacts, the sequestration of CO2in Mg-rich minerals and wastes as part of the global carbon capture and storage strategy and the knowledge transfer of China’s unique expertise and successful practice of MgO in large mass concrete dams. This is a complete reversal to the stigma associated with MgO use in cements (delayed expansion of ‘hard burned’ MgO in PC and poor performance of Sorel cements).
China leads the world in its use of magnesia in large mass concrete structures, with decades of experience and evidence in large dams, which started with the construction of the Baishan dam back in the 1970s, with over 30 more MgO concrete dams constructed in the last 40 years. The image (above) shows the more recent Xiaowan Dam built over a 5 year period (2005-2010); it is 292m high and is the highest double arch dam in the world and in which MgO concrete was employed. The MgO-concrete technology brings significant advantages and benefits in the prevention of thermal cracking, which includes the reduction or even complete elimination of the costly cooling measures which would otherwise be required. The use of MgO saves ~5% of the project costs (Three Gorges dam cost GBP 27B), and speeds up the construction process as the concrete can be cast continually with fewer transverse or longitudinal contraction joints. Over 20 super-large dams are currently planned in China for which the prevention of thermal cracking will be even more challenging because of their very large volumes and complicated structures.
The proposed research will focus on two main areas. The first is the technical advantages and benefits that magnesia can provide to existing cement systems. This includes its use as an expansive additive for large mass concrete constructions e.g. dams and nuclear installations, its role in magnesium phosphate cements for the developing of low pH cements suitable for nuclear waste applications and its role in advancing the development of alkali activated cements by providing low shrinkage and corrosion resistance. The second is the delivery of sustainable MgO production processes that focus on the use of both mineral and reject brine resources. An overarching aspect of the proposed research is the mapping out of the team's capabilities and the integration of expertise and personnel exchange to ensure maximum impact.