Guirguis et al 2018 CBM.pdf (1.67 MB)
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The Application of a New Oxidation Mortar Bar Test to Mixtures containing Different Cementing Systems

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posted on 13.10.2021, 16:53 by Bassili Guirguis, Medhat ShehataMedhat Shehata, Josée Duchesne, Benoît Fournier, Benoît Durand, Patrice Rivard
The effects of different cementing systems on the expansion of mortars containing iron sulphide-bearing aggregate was studied. Using a recently developed oxidation mortar bar test, the results showed that cementing systems containing low-calcium fly ash, metakaolin, slag, high-sulphate resisting Portland cement, or low heat of hydration Portland cement could reduce the expansion by 50–85%. The main suggested mechanisms behind the reduced expansion is the more refined pore structure of samples with SCMs, and the reduced C3A of low heat of hydration Portland cement. The refined pore structure reduces the permeation of the oxidizing solution into the samples. The similarity of this to penetration of oxygen into concrete under field exposure needs to be determined. Soaking the samples for >3 h in the oxidizing agent can produce excessive expansion – not related to oxidation of iron sulphide phases – in samples with cementing blends containing reactive alumina such as metakaolin.

Funding

Funding of this research work was provided by a grant from the Natural Science and Engineering Research Council of Canada (NSERC) and the Ministry of Transportation, Ontario (MTO). Opinions expressed in this paper are those of the authors and may not necessarily reflect the views and policies of MTO.

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