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Title: Prediction of Effective Properties of Fly Ash-Based Geopolymers

Author(s): Sumanta Das, Pu Yang, Sudhanshu S. Singh, James C.E. Mertens, Xianghui Xiao, Nikhilesh Chawla and Narayanan Neithalath

Publication: Symposium Paper

Volume: 335


Appears on pages(s): 49-62

Keywords: Geopolymers, Nanoindentation, Synchrotron Tomography, Homogenization, Microstructure

DOI: 10.14359/51720215

Date: 9/20/2019

A  detailed  microstructural  and  micromechanical  study  of  a  fly  ash‐based  geopolymer  paste  including: (i) synchrotron x‐ray tomography (XRT) to characterize the pores (size > 0.74 m) that are influential in fluid transport, (ii) mercury intrusion porosimetry (MIP) to capture the volume fraction of smaller  pores,  (iii)  high  resolution  scanning  electron  microscopy  (SEM)  combined  with  a  multi‐label  thresholding method to identify and characterize the solid phases in the microstructure, and (iv) nanoindentation  to  determine  the  component  phase  elastic  properties  using  statistical  deconvolution  techniques, is reported in this paper. The 3D pore structure from XRT is used in a computational fluid transport  model  to  predict  the  permeability  of  the  material.  The  pore  volume  from  XRT,  solid  phase  volumes from SEM, and the phase elastic properties are used in a numerical homogenization framework to determine the homogenized macroscale elastic modulus of the composite. The homogenized elastic moduli are in good agreement with the flexural elastic modulus determined on macroscale paste beams. It  is  shown  that  the  combined  use  of  microstructural  and  micromechanical  characterization  tools  at  multiple scales provides valuable information towards the material design of fly ash‐based geopolymers.