Long-term performance of concretes exposed to severe environments

在英国，每年基础设施预算的50%用于维护、维修和更换。随着预计的新基础设施（到2025年将达到4800亿英镑），提高和预测建筑材料的弹性是势在必行的。对混凝土的主要威胁是二氧化碳，大气中二氧化碳的含量达到了创纪录的水平。当二氧化碳进入混凝土时，它会发生反应，这种现象被称为碳化。这会导致钢筋的腐蚀以及水泥完整性的变化，特别是在极端的冬季天气下，会加速损坏。该项目旨在评估结构混凝土在碳化和/或冻融载荷作用下的性能，作为一种模拟实际使用条件的新方法。具体目标是(i)定义不同混凝土化学成分之间的等效性能，（ii）开发将混凝土微观结构与其性能联系起来的综合评估方法；（ii）在真实的模拟条件下评估混凝土时，创建新的合格耐久性标准。这项研究工作将由英国负责公路网长期运营和完整性的机构英格兰公路局、UKCRIC基础设施材料中心和利兹大学布拉格材料研究中心合作进行。博士研究员将可以使用全新的实验室进行胶凝材料的开发，表征和性能评估，包括使用我们自己的光谱和显微镜设备，包括独特的x射线微断层扫描仪器，用于在受控环境（例如温度，气体气氛，湿度）下现场监测孔隙结构变化和微开裂。

In the UK, 50% of the annual infrastructure budget is allocated to its maintenance, repair and replacement. With the projected new infrastructure (£480Bn by 2025), it is imperative to improve and predict the resilience of construction materials. A critical threat to concrete is carbon dioxide, which is present in the atmosphere at record levels. When CO2 enters concrete it reacts, a phenomenon known as carbonation. This leads to corrosion of steel reinforcement as well as changes in the integrity of the cement, accelerating damage particularly when coupled with extreme wintery weather.This project aims to evaluate performance of structural concretes when subjected to loading in combination with carbonation and/or freeze-thaw, as a new approach to simulate realistic in-service conditions. Specific objectives are to (i) define equivalent performance between different concrete chemistries, (ii) develop integrated assessment methods linking the microstructure of concretes to their performance; and (ii) create new conformity durability criteria of concretes when assessed under realistic simulated conditions.The research work will be conducted in collaboration between Highways England, the UK's authority responsible for the road network's long-term operation and integrity, the UKCRIC Centre for Infrastructure Materials and Bragg Centre of Materials Research at the University of Leeds. The PhD researcher will have access to brand new laboratories for the development, characterisation and performance assessment of cementitious materials, including access to our own spectroscopy and microscopy facilities including a unique X-ray microtomography instrument for in-situ monitoring of pore structure changes and microcraking under controlled environments (e.g. temperature, gas atmosphere, humidity).