Physical and Mechanical Response of the Cementation of Aluminosilicate Seals

几十年来，研究断层和地震的地球物理学家一直专注于研究岩石如何在地球内部力量的作用下变弱或断裂。我们需要问的另一个问题是，例如，在两次地震之间，岩石是如何加固的？使岩石更坚固的一个过程是胶结作用。也就是说，地下水穿过岩石中的小孔隙和裂缝，可能会沉积下像胶水或水泥一样的矿物质，从而加固岩石。瓦诺里奥博士和她的团队将进行实验室研究，详细调查水泥是如何形成的，以及它们在各种热和化学条件下对岩石的强化程度。除了帮助科学家了解断层岩石如何在地震之间重建强度之外，瓦诺里奥博士的研究还可以帮助工程师设计出在恶劣化学条件下长期保持强度的材料。因为胶结填满了岩石中的小空隙，使它们更不容易被流体渗透，她的研究也将帮助工程师设计地热系统或选择合适的密封储层来储存温室气体。地壳的活动断层就像大型的窑炉工厂——它们机械地将硅酸铝岩石粉碎到微米或更细的尺度，并在内部传导热量，使断层泥得到处理，并为流体介导的化学反应做好准备，最终导致胶结。地球物理数据显示，地壳的反复断裂和强度恢复——这一过程被称为断层愈合——是一个相对较快的过程。在这个项目中，PI打算通过研究暴露在两种自然过程下的铝硅酸盐的地球化学合成：二氧化碳诱导的碳酸化和碱性水热处理，来提高对地质密封的自然胶结（即摩擦愈合）的认识。为了了解岩石材料在宏观尺度上的物理和机械特性是如何与底层结构联系在一起的，PI计划研究形成的胶凝相的微观和纳米尺度结构，以及它们如何影响强度和破坏模式，以及密封完整性损失（裂纹扩展和破裂）的声学特征。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

For decades, geophysicists studying faults and earthquakes have focused on how rocks weaken or break in response to forces within the Earth. Another question we need to ask is, how do rocks restrengthen, for instance, between earthquakes? One process that makes rocks stronger is cementation. That is, groundwater passing through small pores and cracks in rocks may deposit minerals which act like glue or cement, strengthening the rock. Dr. Vanorio and her group will conduct laboratory studies to investigate in detail just how cements form, and how much they strengthen rocks under a variety of thermal and chemical conditions. In addition to helping scientists understand how faulted rocks rebuild their strength between earthquakes, Dr. Vanorio's research can also help engineers design materials that can maintain their strength under harsh chemical conditions over long periods of time. Because cementation fills small voids in rock and makes them more impervious to fluid flow, her research will also help engineers to design geothermal systems or select suitable sealed reservoirs for storing greenhouse gases.Active faults of the Earth's crust function as large-scale kiln factories — they mechanically pulverize aluminosilicate rocks to the micron or finer scale, and internally channel heat that treats and primes the fault gouge for fluid-mediated chemical reactions, eventually leading to cementation. Geophysical data shows that repeated failures and strength recovery of the Earth’s crust — a process known as fault healing, is a relatively fast process. In this project, the PI intends to advance knowledge on the natural cementation (i.e., frictional healing) of geological seals by studying Earth’s chemical synthesis of aluminosilicates exposed to two natural processes: CO2-induced carbonation and alkaline hydrothermal treatment. To understand how the physical and mechanical properties of rock materials measured at the macro scale connect to the underlying structure, the PI plans to study the micro- and nano-scale structures of the formed cementitious phases and how they influence strength and mode of failure as well as the acoustic signature of the loss of seal integrity (crack propagation and fracturing).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.