MECHANISM OF DAMAGE FOR THE ALKALI-SILICA REACTION: RELATIONSHIPS BETWEEN SWELLING AND REACTION DEGREE

In this study, a damage mechanism is proposed for the alkali-silica reaction. In a first time, a new chemical method has been developed for quantitative measurement of reaction degree in a "reactor model" without cement paste, and in a second time this method has been adapted on mortar bar. Two reaction steps are taken into account in the mechanism: formation of Q3 sites made by breaking up siloxane bonds, and the dissolution of these Q3 sites. It shows that the formation of Q3 sites prevails over dissolution during the swelling step. A relationship is established between the reaction degree characterised by the quantity of Q3 sites in the aggregate and its physical properties characterised by absolute density and specific pore volume. During the swelling step, the density is near-constant while the specific pore volume increases. The physical properties of the aggregate are used to value its expansion, and relationships are made between this expansion and the swelling of mortar bar. It enables to measure a restoration factor of the chemical swelling, which for a stiff and low porous matrix (ratio Water/Cement = 0.35) is high (about 3). These results show that it seems to be the siloxane bonds breaking up by ions OH- of the pore's solution which causes a structural swelling of the siliceous aggregates. From these works, this methodology will be applied on concrete to perfect a diagnosis method. For the covering abstract see ITRD E119166.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0727731750
• Corporate Authors:

  Thomas Telford Limited

  London,   United Kingdom 
• Authors:
  • RICHE, M J
  • GARCIA-DIAZ, M E
  • BULTEEL, M D
  • SIWAK, MJM
  • VERNET, C
• Publication Date: 2002

Language

• English

Media Info

• Features: References;
• Pagination: p. 93-102
• Serial:
  • REPAIR, REJUVENATION AND ENHANCEMENT OF CONCRETE. PROCEEDINGS OF THE INTERNATIONAL SEMINAR HELD UNIVERSITY OF DUNDEE, 5-6 SEPTEMBER 2002
  • Publisher: Thomas Telford Limited

Subject/Index Terms

• TRT Terms: Aggregates; Alkali silica reactions; Chemical reactions; Conferences; Loss and damage; Mortar
• ITRD Terms: 4577: Aggregate; 5222: Alkali silica reaction; 8525: Conference; 1614: Damage; 4769: Mortar; 7156: Reaction (chem)
• Subject Areas: Data and Information Technology; Geotechnology;

Filing Info

• Accession Number: 00966366
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• ISBN: 0-7277-3175-0
• Files: ITRD
• Created Date: Dec 4 2003 12:00AM