Water transport in cements: A bottom - up approach based on NMR relaxation and imaging analysis and numerical modelling

混凝土是一种固有的低能量输入材料（600-800兆焦耳/吨），与木材（500兆焦耳/吨）相当。然而，全球范围内的大量使用意味着它至少占全球二氧化碳产量的5%，到2050年水泥需求将增加一倍/三倍。水在混凝土中的运动是通过物理和化学手段影响基础设施长期性能和退化的关键因素。此外，水是水泥的关键成分，水泥是混凝土的主要粘合剂相。然而，值得注意的是，目前还没有明确的理解，在水泥中的孔隙水的相互作用。同样，混凝土中的水分传输也没有很好的预测方法。为了获得这种理解，将朝着预测混凝土的长期性能和设计每单位性能具有较低水泥CO2排放量的新水泥材料迈出关键一步。到目前为止，大多数理解水泥中水传输的方法都是自上而下的。无论是通过实验还是建模，水泥都被视为宏观材料，可以测量或计算有效水扩散系数。这在很大程度上是一门经验科学，相对而言，很少有人知道如何支持关于不同水传输机制的必要假设。该计划首次提出了一种自下而上的协调方法，从分子（nm）水平上的水泥中的水传输开始，并建立到宏观水平。在每个阶段，在一个长度和时间尺度上获得的理解将支撑下一个阶段的进展。其目标是开发和测试一个水动力学预测模型，该模型可以与瑞士EPFL的Scrivener及其同事开发的水泥化学和微观结构的当前卓越数值模型mu-IC相结合/相连接。该计划将通过将核磁共振弛豫测量的最新进展与水泥微观结构数值模拟的同样令人印象深刻的进展相结合来实现。NMR为我们了解纳米级水泥中的孔隙水相互作用和动力学打开了一扇全新的窗口，在1 ns，10 us和5 ms的时间尺度上识别动力学。数值模拟的进展是基于其他光谱学和显微镜的进展。将这两者结合起来，创造了新的机会来理解，从而从原子尺度上为水泥中的水传输创造了预测能力。该计划将与各自领域的国际合作者密切合作：洛桑联邦理工学院的Karen Scrivener教授和瑞士PSI的Sergey Churakov博士。此外，还有强大的网络，以15个工业和22个学术合作伙伴的主要国际水泥研究网络：NANOCEM。NANOCEM将向该方案捐款57 000英镑，其中包括35 000英镑现金，以及22 000英镑用于萨里郡为期6个月的PDRA，直至2010年3月。项目学生和博士后研究人员将对这些合作者进行长期访问。

Concrete is an inherently low energy input material (600-800 MJ/tonne) comparable to wood (500 MJ/tonne). However, the enormous quantities used worldwide mean that it accounts for at least 5% of global CO2 production with demand for cement set to double / treble by 2050 . Water movement in concrete is a key factor influencing the long term performance and degradation of infrastructure by both physical and chemical means. Moreover, water is a key constituent of cement, the primary binder phase of concrete. However, remarkably, there is as yet no clear understanding of pore-water interactions in cements. Equally there is no good predictor of water transport in concrete. To gain this understanding will achieve a critical step towards predicting the long-term performance of concrete and the design of new cement materials with lower cement CO2 emissions per unit of performance . To date, most approaches to the understanding of water transport in cement have been top down . Whether by experiment or modelling , cement is treated as a macroscopic material for which effective water diffusivities are either measured or calculated. It is largely an empirical science, with relatively little known to underpin the necessary assumptions about different water transport mechanisms. This programme proposes, for the first time, a concerted bottom up approach that begins with water transport in cement at the molecular (nm) level and builds to the macroscopic. At each stage, understanding gained at one length and time scale will underpin progress at the next. The goal is to develop and test a predictive model of water dynamics that can be incorporated within / bolted onto the current pre-eminent numerical model of cement chemistry and micro-structure, mu-IC, developed by Scrivener and co-workers at EPFL, Switzerland.The programme will be achieved by combining recent advances in nuclear magnetic resonance (NMR) relaxometry with equally impressive advances in numerical modelling of cement microstructure. NMR has opened an entirely new window to our understanding of pore water interactions and dynamics in cements at the nanoscale with identification of dynamics on timescales of 1 ns, 10 us and 5 ms. Advances in numerical modelling are based on advances in other spectroscopies and microscopies. Coupling the two creates new opportunity to understand, and hence create predictive capability for water transport in cements from the atomic scale upwards. This programme will be pursued in close collaboration with international collaborators leading in their fields: Professor Karen Scrivener, EPFL and Dr Sergey Churakov, PSI, Switzerland. Moreover, there is strong networking to a major intrnational cements research network of 15 industrial and 22 academic partners: NANOCEM. NANOCEM will contribute 57,000 including 35,000 cash to the programme and 22,000 for a 6 month PDRA at Surrey, up to March 2010. Project students and post-doctoral researchers will make extended visits to these collaborators.