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），必须改善和预测建筑材料的弹性。对混凝土的一个关键威胁是二氧化碳，它在大气中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，这种现象被称为碳酸化。这会导致钢筋的腐蚀以及水泥的完整性的变化，特别是在极端的冬季天气下，会加速损坏。本项目旨在评估结构混凝土在承受碳化和/或冻融组合荷载时的性能，作为模拟实际使用条件的新方法。具体目标是（i）确定不同混凝土化学性质之间的等效性能，（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;及（ii）在真实模拟条件下评估时，建立新的混凝土一致性耐久性标准。研究工作将与英格兰公路局，英国负责道路网长期运营和完整性的权威机构，英国基础设施材料中心和利兹大学布拉格材料研究中心。博士研究员将有机会进入全新的实验室，用于开发，表征和性能评估胶凝材料，包括使用我们自己的光谱和显微镜设施，包括独特的X射线显微断层扫描仪，用于在受控环境（例如温度，气体气氛，湿度）下原位监测孔结构变化和微裂纹。

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).