This study aimed to evaluate the effectiveness of a mechanism responsible for the mitigation of expansion when reactive aggregate powders (RAP) were used in concrete containing the same reactive aggregate. In the first part, it was shown that RAP were efficient in reducing the expansion of concrete by 35 to 95%. The most efficient powders were those coming from aggregates having high active silica contents (glass, opal). Powders of siliceous limestone were less effective. In a second part, experimental evidence of the pozzolanic activity of RAP was obtained. It was shown that RAP were similar to pozzolan, since they consumed lime and produce calcium–silicate–hydrate (C–S–H) having a lower calcium/silica (C/S) ratio than normal C–S–H. The third part showed experimentally that these low C/S C–S–H could increase the redistribution of alkalis of the pore solution, thus reducing the alkalinity of the pore solution to a level that was sufficiently low to limit the attack of coarser reactive aggregates. In the final part, numerical simulations using a modified version of the hydration model CEMHYD3D were carried out to support this assumption.

BACKGROUNDS AND AIMS Thermogenesis in reproductive organs is known from several plant families, including the Araceae. A study was made of the relationship between temperature increase and spadix size in the subfamily Aroideae in order to determine whether the quantitative variation of heat production among species and inflorescences of different sizes follows a physical law of heat transfer. * METHODS Spadix temperature was measured in 18 species from eight genera of tropical Araceae from the basal clade of Aroideae, both in French Guiana and in the glasshouses of the Montreal Botanical Garden. * KEY RESULTS A significant logarithmic relationship was found between the volume of the thermogenic spadix zone and the maximum temperature difference between the spadix and ambient air. Four heat transfer models were applied to the data (conductive heat transfer alone, convective heat transfer alone, radiative heat transfer alone, and convective and radiative heat transfers) to test if physical (geometric and thermic) constraints apply. Which heat transfer model was the most probable was determined by using the criterion of a classical minimization process represented by the least-squares method. Two heat transfer models appeared to fit the data well and were equivalent: conductive heat transfer alone, and convective plus radiative heat transfers. * CONCLUSIONS The increase in the temperature difference between the spadix and ambient air appears to be physically constrained and corresponds to the value of a thermal model of heat conduction in an insulated cylinder with an internal heat source. In the models, a heat metabolic rate of 29.5 mW g(-1) was used, which was an acceptable value for an overall metabolic heat rate in aroid inflorescences.

For a complex enclosure, possibly containing an occupant or furniture, the authors have developed a zone thermal simulation model within the TRNSYS simulation programme that is able to take into account local characteristics of the different solar contributions. This new model has been validated by comparing its results to experimental measurements for several cases. For a given sunny day, different types of results can be determined. One of them corresponds to a cartography of surface temperatures that indicates local overheating on the ground surface receiving the direct solar beam. Then, the knowledge of solar patches in the enclosure allows the authors to calculate the dynamic distribution of solar fluxes onto a person not directly struck by the direct beam.

This aim of this study is to assess the error caused by solar radiation in real-site ambient temperature measurements obtained with a thermocouple and to determine a correction method. The results show that the high values of solar radiation that may occur in highly glazed spaces can have a significant influence on thermocouple measurements. The authors therefore decided to validate and develop a corrective model of the measurement error based on an energy balance of the sensor The influence of the various parameters was studied and the most important error was found to occur when solar fluxes were neglected. They therefore propose a simplified equation to correct the error measurement.