Fundamental physical properties of graphene reinforced concrete

不断增长的全球人口和日益警觉的全球气候变化要求建筑业取得新的、颠覆性的进步。混凝土和水泥是最广泛使用的建筑材料，其制造业占全球碳排放的10%以上，而且这一数字每年都在继续增长。这个博士项目正在解决的研究问题是开发一种新的方法，利用石墨烯等原子稀薄材料对传统混凝土进行纳米工程。该项目的目标是：1)调查石墨烯是否会引起化学反应的任何变化，从而导致混凝土的基本机械性能；2)表征在添加石墨烯后结构材料的强度、耐久性、防水和热传递方面的任何变化。解决这些问题的新的工程方法是在混凝土成分中加入石墨烯，通过在液体中均匀分散来取代水。为此，首先开发了一种新的石墨烯液体剥离方法，并利用拉曼光谱对得到的水悬浮液进行了充分的表征。然后，根据英国的施工标准制备混凝土试件，并测试各种性能，如抗压和抗折强度、循环荷载、防水和热传输。为了了解混凝土内部基质平面之间微结构裂缝的形成和扩展，以及石墨烯对混凝土总断裂能力和抗力的影响，进行了单独的深入研究。最后，利用X射线衍射仪对水泥水化产物的微晶度进行了多次实验研究。

The increasing global population and the alerting global climate change demand novel and disruptive advancements of the construction industry. Manufacturing of concrete and cement, the most widely used construction materials, accounts for more than 10% of global carbon emissions and this number continues to grow each year. The research questions that this PhD project is addressing is the development of a novel method of nano-engineering traditional concrete with atomically thin materials such as graphene. The objectives of the project are: 1) to investigate if graphene introduces any changes to the chemical reactions, responsible for the fundamental mechanical properties of concrete; 2) to characterise any changes in the strength, durability, water impermeability and heat transfer of the structural material upon adding graphene to it. The novel engineering approach taken to answer these questions is by adding graphene to the concrete composition by substituting water via uniform dispersion in liquid. To this end, first a novel method of liquid exfoliation of graphene is developed and the resulting water suspensions fully characterised using Raman spectroscopy. Then, concrete samples are prepared according to British standards for construction and tested for various properties such as compressive and flexural strength, cyclic loading, water impermeability and heat transport. A separate in-depth study is carried out to understand the formation and propagation of micro-structural cracks between the concrete's internal matrix planes, and graphene's impact on total fracture capacity and resistance of concrete. Lastly, multiple experiments are performed to investigate the microcrystallinity of cement hydration products using X-ray diffraction.