Coupled transport and poro-mechanical properties of a heat-treated mortar under confinement

Xiao-Ting Chen (1) , Grégory Caratini (2) , Catherine A. Davy (1) , David Troadec (3) , Frédéric Skoczylas (1)

1 LML - Laboratoire de Mécanique de Lille - FRE 3723
2 navier umr 8205 - Laboratoire Navier
3 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520

This experimental investigation focuses on a mortar heated/cooled up to 105, 200, 300 or 400 °C. The reference state for the material corresponds to mass stabilization at 60 °C oven-drying. Extensive (and tortuous) micro-crack development is shown by SEM and FIB/SEM imaging after heating-cooling up to 400 °C. Poro-mechanical performance is significantly affected after 400 °C heat-treatment, as plastic straining develops with increasing hydrostatic stress Pc; simultaneously, intrinsic gas permeability Kint decreases irreversibly after a first loading, and remains significantly lower whatever the subsequent Pc loading. These results are mainly attributed to the irreversible closure of heat-induced micro-cracks. This interpretation, based on our micro structural analysis, is validated experimentally under hydrostatic loading: a dedicated static gas experiment provides directly the pore volume under given Pc. By comparison with experimental data on heat-treated cement paste, we conclude that the irreversible pore closure of heat-treated mortar is related to that of micro-cracks mainly located at the paste/aggregate interface.

Mots clés: Thermal treatment (A); Poro-mechanics (C); Gas permeability (C); Hydrostatic stress (C); Connected porosity (B)

Xiao-Ting Chen, Grégory Caratini, Catherine A. Davy, David Troadec, Frédéric Skoczylas. Coupled transport and poro-mechanical properties of a heat-treated mortar under confinement. Cement and Concrete Research, 2013, 49, pp.10-20. ⟨10.1016/j.cemconres.2013.03.006⟩. ⟨hal-00812167⟩