Fundamental physical properties of graphene reinforced concrete

不断增长的全球人口和日益严重的全球气候变化要求建筑行业取得突破性的进步。混凝土和水泥是最广泛使用的建筑材料，其生产占全球碳排放量的10%以上，而且这一数字每年都在持续增长。这个博士项目正在解决的研究问题是开发一种新的纳米工程方法，用石墨烯等原子薄材料来制造传统混凝土。该项目的目标是：1)研究石墨烯是否会对混凝土基本力学性能的化学反应产生任何变化；2)描述添加石墨烯后结构材料在强度、耐久性、抗水性和传热方面的任何变化。为了回答这些问题，一种新颖的工程方法是在混凝土成分中加入石墨烯，通过均匀分散在液体中来取代水。为此，首先开发了一种新型的石墨烯液体剥离方法，并使用拉曼光谱对所产生的水悬浮液进行了充分表征。然后，根据英国建筑标准制备混凝土样品，并进行各种性能测试，如抗压和抗弯强度、循环荷载、抗水性能和传热性能。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折能力的影响，我们进行了单独的深入研究。最后，利用x射线衍射对水泥水化产物的微结晶度进行了研究。

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.