Assessing concrete density using infrared thermographic (IRT) images

This paper presents the results of a study conducted to evaluate the possibility of utilizing infrared thermography to assess the quality of concrete. Concrete specimens were prepared with varying water to cement (w/c) ratio, cement content and consolidation effort. The concrete specimens were heated and the IRT images were recorded as they cooled down. The IR thermographs indicated a good variation in the surface temperature with varying concrete composition and consolidation effort. Concrete with similar composition exhibited a greater variation in surface temperature as the consolidation effort was decreased; indicating the presence of less dense structure in the specimens prepared with low consolidation effort. An increase in the water–cement ratio also increases the temperature variation indicating a decrease in the concrete denseness. The variation in cement content also influenced the denseness of concrete as indicated by the enhanced variation in the surface temperature. Concrete specimens with cement content of 300 kg/m³ (less dense) exhibited a greater temperature variation compared to those prepared with cement content of 400 kg/m³ (more dense).     

On the thermal anisotropy affecting transfers in a multilayer porous mediumSur l'effet de l'anisotropie thermique sur les transferts dans un milieu poreux multicouches

An analytical model for studying double-diffusive natural convection within a multilayer anisotropic porous medium is developed and validated with respect to a direct numerical silmulation. The studied domain is composed of two horizontal porous layers where the lower one is thermally anisotropic and is submitted to a uniform horizontal heat flux and a vertical mass flux. The assumption of parallel flow is validated and the effect of anisotropy on dynamic transitions is investigated. To cite this article: R. Bennacer et al., C. R. Mecanique 332 (2004).