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Title: Evolution of the pore structure during the early stages of the alkali-activation reaction: An in situ small-angle neutron scattering investigation

The long-term durability of cement-based materials is influenced by the pore structure and associated permeability at the sub-micrometre length scale. With the emergence of new types of sustainable cements in recent decades, there is a pressing need to be able to predict the durability of these new materials, and therefore nondestructive experimental techniques capable of characterizing the evolution of the pore structure are increasingly crucial for investigating cement durability. Here, small-angle neutron scattering is used to analyze the evolution of the pore structure in alkali-activated materials over the initial 24 h of reaction in order to assess the characteristic pore sizes that emerge during these short time scales. By using a unified fitting approach for data modeling, information on the pore size and surface roughness is obtained for a variety of precursor chemistries and morphologies (metakaolin- and slag-based pastes). Furthermore, the impact of activator chemistry is elucidatedviathe analysis of pastes synthesized using hydroxide- and silicate-based activators. It is found that the main aspect influencing the size of pores that are accessible using small-angle neutron scattering analysis (approximately 10–500 Å in diameter) is the availability of free silica in the activating solution, which leads to a more refined pore structure withmore » smaller average pore size. Furthermore, as the reaction progresses the gel pores visible using this scattering technique are seen to increase in size.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Princeton Univ., Princeton, NJ (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); European Spallation Source, Lund (Sweden)
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Crystallography (Online)
Additional Journal Information:
Journal Name: Journal of Applied Crystallography (Online); Journal Volume: 50; Journal Issue: 1; Journal ID: ISSN 1600-5767
Publisher:
International Union of Crystallography
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; small-angle neutron scattering; alkali-activated materials; pore structure; gel pores; nanoscale morphology
OSTI Identifier:
1342705

White, Claire E., Olds, Daniel P., Hartl, Monika, Hjelm, Rex P., and Page, Katharine. Evolution of the pore structure during the early stages of the alkali-activation reaction: An in situ small-angle neutron scattering investigation. United States: N. p., Web. doi:10.1107/S1600576716018331.
White, Claire E., Olds, Daniel P., Hartl, Monika, Hjelm, Rex P., & Page, Katharine. Evolution of the pore structure during the early stages of the alkali-activation reaction: An in situ small-angle neutron scattering investigation. United States. doi:10.1107/S1600576716018331.
White, Claire E., Olds, Daniel P., Hartl, Monika, Hjelm, Rex P., and Page, Katharine. 2017. "Evolution of the pore structure during the early stages of the alkali-activation reaction: An in situ small-angle neutron scattering investigation". United States. doi:10.1107/S1600576716018331. https://www.osti.gov/servlets/purl/1342705.
@article{osti_1342705,
title = {Evolution of the pore structure during the early stages of the alkali-activation reaction: An in situ small-angle neutron scattering investigation},
author = {White, Claire E. and Olds, Daniel P. and Hartl, Monika and Hjelm, Rex P. and Page, Katharine},
abstractNote = {The long-term durability of cement-based materials is influenced by the pore structure and associated permeability at the sub-micrometre length scale. With the emergence of new types of sustainable cements in recent decades, there is a pressing need to be able to predict the durability of these new materials, and therefore nondestructive experimental techniques capable of characterizing the evolution of the pore structure are increasingly crucial for investigating cement durability. Here, small-angle neutron scattering is used to analyze the evolution of the pore structure in alkali-activated materials over the initial 24 h of reaction in order to assess the characteristic pore sizes that emerge during these short time scales. By using a unified fitting approach for data modeling, information on the pore size and surface roughness is obtained for a variety of precursor chemistries and morphologies (metakaolin- and slag-based pastes). Furthermore, the impact of activator chemistry is elucidatedviathe analysis of pastes synthesized using hydroxide- and silicate-based activators. It is found that the main aspect influencing the size of pores that are accessible using small-angle neutron scattering analysis (approximately 10–500 Å in diameter) is the availability of free silica in the activating solution, which leads to a more refined pore structure with smaller average pore size. Furthermore, as the reaction progresses the gel pores visible using this scattering technique are seen to increase in size.},
doi = {10.1107/S1600576716018331},
journal = {Journal of Applied Crystallography (Online)},
number = 1,
volume = 50,
place = {United States},
year = {2017},
month = {2}
}