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Title: Influence of amorphous silica on the hydration in ultra-high performance concrete

Amorphous silica particles (silica) are used in ultra-high performance concretes to densify the microstructure and accelerate the clinker hydration. It is still unclear whether silica predominantly increases the surface for the nucleation of C–S–H phases or dissolves and reacts pozzolanically. Furthermore, varying types of silica may have different and time dependent effects on the clinker hydration. The effects of different silica types were compared in this study by calorimetric analysis, scanning and transmission electron microscopy, in situ X-ray diffraction and compressive strength measurements. The silica component was silica fume, pyrogenic silica or silica synthesized by a wet-chemical route (Stoeber particles). Water-to-cement ratios were 0.23. Differences are observed between the silica for short reaction times (up to 3 days). Results indicate that silica fume and pyrogenic silica accelerate alite hydration by increasing the surface for nucleation of C–S–H phases whereas Stoeber particles show no accelerating effect.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [1] ;  [2]
  1. Fraunhofer–Institute for Silicate Research ISC, Neunerplatz 2, 97082 Würzburg (Germany)
  2. (Germany)
  3. Crystallography and X-ray Methods, Technische Hochschule Nürnberg Georg Simon Ohm, Wassertorstraße 10, 90489 Nürnberg (Germany)
  4. Building Materials, Bauhaus–Universität Weimar, Coudraystr. 11, 99423 Weimar (Germany)
Publication Date:
OSTI Identifier:
22323134
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 58; 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; CALORIMETRY; CEMENTS; COMPRESSION STRENGTH; CONCRETES; HYDRATION; MICROSTRUCTURE; NUCLEATION; PARTICLES; SILICA; TIME DEPENDENCE; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION