ASSESSMENT OF CHLORIDE INGRESS IN BLENDED CEMENT WITH COMBINED ADDITION OF CALCINED CLAYS AND LIMESTONE

Author(s): Antoni, M., Henocq, P., Kazemi-Kamyab, H., Favier, A., Martirena, F. and Scrivener, K.
Paper category: Conference
Book title: XIII International Conference on Durability of Building Materials and Components - XIII DBMC
Editor(s): Marco Quattrone, Vanderley M. John
Print ISBN: none
e-ISBN: 978-2-35158-149-0
Publication year: 2015
Pages: 1106-1113
Total Pages: 8
Language: English

Abstract: Substitution with pozzolanic materials such as calcined clays, even of average purity, is known to improve concrete properties. However above a certain threshold commonly accepted to be of about 30% of substitution, these materials reduce the mechanical properties, especially at early age. In this contribution the combined addition of calcined clays and limestone is investigated. Previous results have indeed shown that there is a synergetic effect with formation of carbo-aluminates phases in this ternary system and that 45% of substitution by 30% of metakaolin and 15% of limestone powder gives better mechanical properties at 7 and 28 days than the 100% OPC reference. The porosity is indeed globally refined.

In this contribution, the resistance to chloride ingress has been studied by the STADIUM migration test on mortars. It has been set up for one pure metakaolin and for natural calcined clay, in binary blend with pure metakaolin alone and in ternary blend with combined addition of 30% calcined clays and 15% limestone.

Both blended cement, with and without further substitution of cement by limestone powder have demonstrated to significantly reduce the diffusion coefficient of chloride ions. It is attributed to the refinement and increased tortuosity of the pore structure.

Online publication: 2015
Publication Type: full_text
Public price (Euros): 0.00