Durable Nano-Engineered Cementitious Systems

耐久性问题困扰着水泥系统：损坏可能是由物理原因--收缩和热裂--或化学环境引起的。传统建筑材料和现代系统都同样容易受到影响，为了确保它们的寿命，混凝土技术人员需要认真考虑。性能与微观结构密切相关：气孔网络、水化产物的稳定性以及体系中各界面的粘结。在很大程度上，研究主要集中在房地产的宏观工程上，即。治标不治本！然而，构建的基础是纳米级的，这需要协调一致地专注于调整此类系统的物理和化学性质，以适应每一种应用。 纳米技术使我们能够理解、控制和重构纳米量级的胶凝系统中的物质。由于其尺寸，纳米材料具有赋予新的和/或显著改善物理、化学、生物和电子性能的能力。申请人对纤维素基(因此，可持续的)纳米纤维进行了初步研究，以说明其内部固化和解决收缩的效率，特别是在平板加工中。此外，在水硬性石灰砂浆中使用纳米二氧化硅和纳米微粒的初步研究结果表明，它们的粘结性能得到了改善，并且具有优异的水密性。该计划的重点是使用这些和类似的纳米材料作为模板，在模板上接枝合适的化学基团，以获得可调的纳米试剂。因此，纳米工程有望提供新一代定制的多功能复合材料，具有一系列有用的性能，如低电阻率、自感知能力、高延展性、自修复和在各种不利的物理和化学环境中控制裂纹。 在短期内，这项建议将：(I)提高水泥基系统的耐久性；(Ii)改善非硅酸盐水泥系统的就地能力和水化特性；以及(Iii)通过增值的工业和农业废物开发创新的粘结剂。长期目标是为可持续建筑确定和开发耐用建筑材料的特征。 四名研究生研究助理(两名博士和两名硕士)以及多名本科生研究实习生将在这项资助的任期内直接与申请者一起积极参与拟议的研究。此外，作为该计划的一部分，他们将与盟国地区的研究人员进行互动。通过一系列不同的学生研究人员的参与，将向新一代高素质人员介绍先进生物材料、纳米材料、化学定量识别技术、计算模拟和高性能结构材料的使用。

Durability issues plague cementitious systems: The distress could arise either from physical causes -shrinkage and thermal cracking- or from the chemical environment . Both traditional building materials and modern systems are equally susceptible and ensuring their longevity seriously engages concrete technologists. Performance is related intimately to the microstructure: air-void network, stability of hydration products and the bond at various interfaces in the system. For the most part, research has focused largely at macro-engineering of properties, ie. treating the symptom but not the cause! However, the building block is at the nanometric scale, which warrants a concerted focus on tailoring the physical and chemical properties of such systems to suit each application. Nanotechnology enables us to understand, control, and restructure matter within cementitious systems in the order of nanometers. Because of their size, nanomaterials have the ability to impart novel and/or significantly improved physical, chemical, biological and electronic properties. This applicant has conducted pilot studies on cellulose based (and hence, sustainable) nanofibres to illustrate their efficiency with internal curing and address shrinkage, especially in flatwork. Further, preliminary investigation on nanosilica and nanolime in hydraulic lime mortars resulted in improved bond behavior and also superior water tightness. The focus of the program proposed here is to employ these and similar nanomaterials as templates upon which suitable chemical groups shall be grafted to achieve tunable nano-agents. Thus, nano-engineering is expected to render a new generation of tailored, multifunctional composites with a range of useful properties such as low electrical resistivity, self-sensing ability, high ductility, self-healing and control of cracks in a variety of adverse physical and chemical environments. In the short term, this proposal will: (i) improve durability of cement based systems; (ii) improve place-ability and hydration characteristics in non-Portland cement systems and (iii) develop innovative binders through value added industrial and agro waste materials. The long term goal is to characterize and develop durable building materials for sustainable construction. Four graduate research assistants (2 PhD and 2 MSc) along with multiple undergraduate research interns will be directly active with the applicant on the proposed research during the tenure of this grant. In addition, they will interact with research personnel in allied areas, as part of this program. Through the involvement of a diverse set of student researchers, a new generation of high quality personnel will be introduced to the use of advanced biomaterials, nanomaterials, identification techniques for chemical quantification, computational simulations and high performance structural materials.