Development of silica-enriched cement-based materials with improved aging resistance for application in high-temperature environments
Name
Ulm_Development of silica-enriched.pdf
Description
Accepted version
Size
2.94 MB
Format
Adobe PDF
Checksum (MD5)
556c77034db09de6fa1c08e2bc06a64b
Author(s)
Krakowiak, Konrad J
Thomas, Jeffrey J
James, Simon
Abuhaikal, Muhannad
Ulm, Franz-J
Date Issued
2018
Journal
Cement and Concrete Research
Publisher
Elsevier BV
Version
Author's final manuscript
Abstract
© 2018 Understanding the effects of high temperature (HT) and high pressure (HP) conditions on the microstructure of cement-based materials is critical to the construction and safe operation of deep oil and gas wells. Under such conditions, the persistence of calcium-silicate-hydrate (C-S-H) gel is compromised by ongoing crystallization that, if not controlled, may adversely affect the durability of the cement sheath. This work investigates the effect of silica content >35% by-weight-of-cement (BWOC), silica particle size, and solid volume fraction (SVF) on the microstructure and phase composition of cement-silica blends cured hydrothermally at 200 °C and 20.7 MPa. The results of X-ray diffraction and electron microprobe analysis revealed significant impact of these three mix design parameters on the final phase assembly, and on the conversion rate of semi-crystalline C-S-H to gyrolite and 11 Å tobermorite. Incorporation of more fine siliceous material suppressed dissolution of coarse silica particles, resulting in a matrix with improved homogeneity and dominated by fine gel pores. Mixes with lower SVF showed greater formation of 11 Å tobermorite, a higher degree of crystallinity and/or greater crystallite size. Prolonged HTHP curing of all systems (up to three months in this study), irrespective of the initial SVF, increased the fraction of capillary pores, indicating void coalesce caused by crystal growth. However, we find that this coarsening is less pronounced in systems with less pore space available for crystallization.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivs License
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DOI of Published Version
https://doi.org/10.1016/J.CEMCONRES.2018.01.004
