Title: Durability Performance of Blended Cement with Calcined Illitic Shale

Author(s): G. P. Cordoba, A. Rossetti, S. V. Zito, V. F. Rahhal, D. Falcone, and E. F. Irassar

Publication: Materials Journal

Volume: 119

Issue: 1

Appears on pages(s): 134-144

Keywords: alkali-silica reaction; calcined clays; calcined shale; chloride penetration; durability; illite; sulfate attack

DOI: 10.14359/51734192

Date: 1/1/2022

Abstract:
The use of calcined clays in cement (kaolinitic and common calcined clays) introduces challenges due to the high alumina content, large specific surface area, and high-alkali content. This paper examines the performance against sulfate attacks, alkali-silica reactions, and chloride penetration in mixtures with calcined illitic shale (CIS). Replacement of high and moderate alkali content cement with 25% CIS significantly reduces the expansion in the alkali-silica reaction (ASR) test, as the pozzolanic reaction contributes to the combination of alkalis. Replacing 20% white portland cement with CIS allows the formulation of sulfate-resistant cement by limiting the formation of gypsum and ettringite. The incorporation of 25% CIS in concrete does not significantly increase chloride ingress. Therefore, blended cements with replacement levels of 20 to 25% of portland cement by CIS reduce or maintain the performance against ASR, sulfate attack, and chloride penetration.