Influence of relative humidity on Delayed Ettringite Formation

Mohamad Al Shamaa (1) , Stéphane Lavaud (2) , Loïc Divet (2) , Georges Nahas (1) , Jean Michel Torrenti (3)

1 IRSN - Institut de Radioprotection et de Sûreté Nucléaire
2 IFSTTAR/MAST/CPDM - Comportement Physico-chimique et Durabilité des Matériaux
3 IFSTTAR/MAST - Département Matériaux et Structures

This experimental study aims to determine the effect of relative humidity on concrete expansion due to delayed ettringite formation (DEF), which still remains imperfectly known. Test methods were designed to trigger reaction in concrete specimens and determine how ambient RH affects expansion of the specimens. Saturated salts solutions were used to achieve distinct ambient RH conditions within containers. Also, chemical analysis was performed to determine and quantify the fractions of alkalis leaching out of the pore solutions of concretes. Results showed that the critical ambient RH value that corresponds to significant suppression of DEF could be greatly dependent on the alkalis fractions leached out. Finally, the consequences of swelling due to DEF on the concrete properties are assessed. After swelling, both of gas permeability and porosity was increased significantly and dynamic modulus was reduced by about 45%.

Mots clés: BETON; HUMIDITE; ALCALI REACTION; PERMEABILITE; PROPRIETE MECANIQUE; FORMATION DIFFEREE D'ETTRINGITE; TENEUR EN EAU; BETON JEUNE

Domaines: Matériaux; Mécanique des matériaux [physics.class-ph]

Mohamad Al Shamaa, Stéphane Lavaud, Loïc Divet, Georges Nahas, Jean Michel Torrenti. Influence of relative humidity on Delayed Ettringite Formation. Cement and Concrete Composites, 2015, 58, pp.14-22. ⟨10.1016/j.cemconcomp.2014.12.013⟩. ⟨hal-01214456⟩