Durable Nano-Engineered Cementitious Systems

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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.***