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Aggregate expansivity due to sulfide oxidation - I. Reaction system and rate model
Oxidation and hydration of sulfides in aggregate materials can yield to expansive reactions that affect the durability of concrete. This process is, in principle, independent from the potential alkali-aggregate reactivity, and the oxidation of the sulfide is the rate-limiting reaction. A model is presented to evaluate the kinetic evolution of expansion due to sulfide oxidation, and subsequent sulfate attack on the paste. The effects of sulfide oxidation on aggregate expansion and sulfate attack of the cement are chiefly controlled by the kinetics of the weathering process, which is the rate-limiting step. The progress of the expansive reaction is governed by the change in surface area of the reactants and, therefore, depends strongly on the original grain size of the sulfides in the aggregate. Under alkaline conditions, ferrihydrate is the most stable product of sulfide oxidation; however, the volume increase associated with its formation is small compared to that of monosulfate or ettringite production from reaction of sulfate ions with portlandite and or tricalcium aluminate.
Aggregate expansivity due to sulfide oxidation - I. Reaction system and rate model
Oxidation and hydration of sulfides in aggregate materials can yield to expansive reactions that affect the durability of concrete. This process is, in principle, independent from the potential alkali-aggregate reactivity, and the oxidation of the sulfide is the rate-limiting reaction. A model is presented to evaluate the kinetic evolution of expansion due to sulfide oxidation, and subsequent sulfate attack on the paste. The effects of sulfide oxidation on aggregate expansion and sulfate attack of the cement are chiefly controlled by the kinetics of the weathering process, which is the rate-limiting step. The progress of the expansive reaction is governed by the change in surface area of the reactants and, therefore, depends strongly on the original grain size of the sulfides in the aggregate. Under alkaline conditions, ferrihydrate is the most stable product of sulfide oxidation; however, the volume increase associated with its formation is small compared to that of monosulfate or ettringite production from reaction of sulfate ions with portlandite and or tricalcium aluminate.
Aggregate expansivity due to sulfide oxidation - I. Reaction system and rate model
Ausdehnung von Zuschlagstoffen aufgrund einer Sulfidoxidation. Teil 1: Reaktionssystem und Modell der Reaktionsgeschwindigkeit
Casanova, I. (author) / Agullo, L. (author) / Aguado, A. (author)
Cement and Concrete Research ; 26 ; 993-998
1996
6 Seiten, 1 Bild, 2 Tabellen, 7 Quellen
Article (Journal)
English
Aggregate Expansivity Due to Sulfide Oxidation - I. Reaction System and Rate Model
| British Library Online Contents | 1996
Aggregate Expansivity Due to Sulfide Oxidation - I. Reaction System and Rate Model
| Online Contents | 1996
Aggregate Expansivity due to Sulfide Oxidation - II. Physico-Chemical Modeling of Sulfate Attack
| Online Contents | 1997
Aggregate Expansivity due to Sulfide Oxidation - II. Physico-Chemical Modeling of Sulfate Attack
| British Library Online Contents | 1997