Ignasi Casanova

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.Abstract 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.

Aggregate expansivity due to sulfide oxidation : II. Physico-chemical modeling of sulfate attack

Abstract Weathering of sulfide-bearing aggregates in concrete causes the release of sulfate ions that can react with cement components to yield expansive products. The extent of the sulfate attack of the paste is controlled by the composition and size of the aggregate, the kinetics of sulfide oxidation, the composition of cement and mix proportioning of concrete. The extent of sulfate attack has been successfully simulated using a combined kineticthermodynamic approach

Calcite interaction with acidic sulphate solutions: a vertical scanning interferometry and energy-dispersive XRF study

This work was financially supported by the CYCIT Project CGL2010-20984-C02-01, by Fundacio´n Ciudad de la Energi´a (Spanish Government) (project ALM11/009) and by the European Union through the ‘‘European Energy Programme for Recovery’’ and the Compostilla OXYCFB300 project and by the PANACEA project (European Community’s Seventh framework Programme FP7/2007-2013 under grant agreement number 282900). The first author is grateful to the National Science Fund of the Bulgarian Ministry of Education and Science (NZMU-1503 and DO1-904).