Experimental study of the evolution of heat and moisture transfer parameters of a concrete slab

After casting, concrete slab upper surfaces are seldom protected. Therefore, depending on the distance to the surface, water distributes itself differently between hydration and drying. The effect of this is the appearance of gradients for the parameters characterising heat and moisture transfers within such porous media. In the present paper, after a possible modelling and a specific metrology of these transfers are evoked, the experiment conducted to reveal and examine the evolution of these gradients with time is discussed. Some divergences (already mentioned in the literature) appear as regards moisture diffusivity depending whether a static or a dynamic approach is chosen. Lastly, experimental results, in particular those concerning heat transfers, could contribute to the feeding of a data bank for the use of future modelling

Early-age autogenous cracking of cementbased systems: from physico-chemical analysis to micro/macro investigations

High-performance cement-based materials, characterized by a low water-tocement (W/C) ratio and a high cement content, are particularly sensitive to early-age cracking because the magnitude and the rate of autogenous shrinkage they develop during this period, are particularly high. This article presents a parametric study carried out in order to quantify the influence of W/C ratio, cement type, curing temperature and aggregates content on the evolution of physico-chemical deformations and the early-age cracking risk they can generate

Numerical modelling of the tensile splitting test and its coupling with gas permeability

International audienc

Early age and mechanical properties of environmentally friendly Ultra-High-Performance Concrete (UHPC)

International audienc

Effect of Temperature on Chloride Diffusion in Saturated Concrete

International audienc

A quantitative assessment of rockfall influence on forest structure in the Swiss Alps

Forests below rocky cliffs often play a very important role in protecting settlements against rockfall. The structure and development of these forests is expected to be substantially affected by the disturbance of the falling rocks. Knowing about this effect is important to predict the development of protection forests and consider potential effects of the falling blocks in management strategies. The goal of this study is to quantify differences in forest structure depending on rockfall activity in four different sites in the Swiss Alps. For this, we collected data on forest structure in zones of different rockfall activity and derived rockfall impact probabilities based on rockfall simulations. We assessed whether differences in forest structure and signs of rockfall disturbance could be observed between the rockfall zones. We additionally built mixed effects models to identify the key variables explaining the forest characteristics described by diameter (DBH) and basal area (bA). The forest structure differs between the rockfall zones, however, with varying effects amongst the sites. DBH tends to decrease with increasing rockfall activity, whereas tree density appears to be little impacted by rockfall. For most sites, the number of deposited blocks and the simulated tree impact probability have a significant effect in the models along with the species, whereas for one site, hardly any effect of rockfall was found. Our results, obtained either from direct measurements or modeling, show that rockfall can locally influence the structure of forests, whereas the influence depends on the frequency and intensity of the rockfall disturbance. Impact probabilities obtained by simulations can serve as a good proxy for rockfall disturbances