EAGER: Computed Tomography of Early Age Structure of Hydrated Portland Cement

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

This EArly-concept Grant for Exploratory Research (EAGER) project advances the use of X-ray computed tomography (CT) to view cement microstructure like never before: three-dimensional images of undisturbed wet samples as a function of time. While CT is emerging as a powerful tool that is available to more and more researchers, the literature remains sparse. Proof of concept experiments have demonstrated the power of these new tools to provide profound new insights into cement hydration and microstructure development. The primary objectives of this project are the development of experimental methods for time studies of hydrating Portland cement. Such experiments require high resolution, high precision sample holders to assure spatial registration over time, special sealed sample holders that prevent evaporation, and special sample preparation techniques to assure that samples are representative of bulk cement, and imaging protocols to assist in segmentation of phases. The proposed study will use university-based nano-scale X-ray computed tomography (funded by an NSF large equipment grant) and Argonne National Lab synchrotron x-ray computed tomography. The synchrotron CT offers high resolution, but is not ideal for long term studies by students. The university CT offers superior access for students for long term studies, but suffers from being lower x-ray flux. This EAGER project aims where little work has been conducted, little precedent has been developed for experimental methods, but great potential exist to advance the science of understanding the complex microstructure of porous solids like hydrated portland cement. Study of microstructure and material modeling have broad impacts in helping us understand cement and concrete properties, durability, life cycle performance, and sustainability. There is no question that improved understanding of materials has potential to improve building materials and extend the service life of the built infrastructure. The high resolution 3-dimensional images that will be acquired in this project provide important insight into the pore network and distribution of phases that control material properties of concrete. Such knowledge will lead to new products and processes that will improve concrete materials in the future.