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Title: Intrinsic differences in atomic ordering of calcium (alumino)silicate hydrates in conventional and alkali-activated cements

The atomic structures of calcium silicate hydrate (C–S–H) and calcium (–sodium) aluminosilicate hydrate (C–(N)–A–S–H) gels, and their presence in conventional and blended cement systems, have been the topic of significant debate over recent decades. Previous investigations have revealed that synthetic C–S–H gel is nanocrystalline and due to the chemical similarities between ordinary Portland cement (OPC)-based systems and low-CO{sub 2} alkali-activated slags, researchers have inferred that the atomic ordering in alkali-activated slag is the same as in OPC–slag cements. Here, X-ray total scattering is used to determine the local bonding environment and nanostructure of C(–A)–S–H gels present in hydrated tricalcium silicate (C{sub 3}S), blended C{sub 3}S–slag and alkali-activated slag, revealing the large intrinsic differences in the extent of nanoscale ordering between C–S–H derived from C{sub 3}S and alkali-activated slag systems, which may have a significant influence on thermodynamic stability, and material properties at higher length scales, including long term durability of alkali-activated cements.
Authors:
 [1] ;  [2] ;  [2] ;  [2] ; ; ;  [3]
  1. Department of Civil and Environmental Engineering, Princeton University, Princeton (United States)
  2. (United States)
  3. Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos (United States)
Publication Date:
OSTI Identifier:
22395937
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 67; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CALCIUM; CALCIUM SILICATES; CARBON DIOXIDE; CRYSTALS; GELS; HARDNESS; HYDRATES; NANOSTRUCTURES; PORTLAND CEMENT; SERVICE LIFE; SLAGS; SODIUM; WEAR RESISTANCE; X RADIATION; X-RAY DIFFRACTION