L3 Médical (France)

In recent years, bio-based building materials have become increasingly popular in the field of low-carbon construction. Different bio-based solutions are being adopted because of their advantageous hygrothermal properties and low economic and environmental costs. One such bio-based solution is hemp mortar, which is used in France and other countries for various construction purposes, such as thermal or acoustic insulation for interior and exterior walls. However, the use of hemp mortars is hampered by insufficient data on their durability and risk of degradation due to natural environmental conditions. Indeed, hemp mortar is hygroscopic, heterogeneous and anisotropic, which makes it difficult to study its behaviour. Therefore, the main objective of this work is to investigate the effect of natural aging on the chemical composition of hemp mortar exposed outside in specially designed metal cage for two years. Experimentally, XRD and thermogravimetric analyses of hemp mortar samples were performed. All experimental results were compared with the results of reference samples treated under laboratory conditions. The effects of two different compositions and sample depths were also investigated. In general, the results showed a higher degree of degradation of the mineral matrix of hemp mortar during natural aging due to carbonation and hygrothermal stresses.

Abstract Two methods are proposed to characterize the thermal fingerprint of a binder from an insulated mockup test realized on a jobsite, rather than using a classic quasi-adiabatic test in lab condition. The first part introduces the model used to compute the temperature evolution at early age, using a Finite Element solver. The second part presents the two methods. The first method is based on the estimation of the heat loss of the mockup. Then, a methodology similar to a standard quasi-adiabatic test is done, by computing (i) the total heat generated during hydration, (ii) the hydration rate and (iii) the chemical affinity. The second method is based on an imposed form of the hydration affinity function, with three parameters. A Finite Element model of the mockup is used, and a minimisation between the computed temperature evolution and the experimental one allow to identify the three parameters. The two methods are validated on a purely numerical study. Then, a real example is presented, and the relevance of the two methods are discussed. KeywordsHeat of hydrationMassive structuresEarly age behaviorTemperature evolution

The results of phase 1 of an interlaboratory test, coordinated by the RILEM TC 267-TRM “Tests for Reactivity of Supplementary Cementitious Materials” showed that the R3 (rapid, relevant, reliable) test method, by measurement of heat release or bound water, provided the most reliable and relevant determination of the chemical reactivity of supplementary cementitious materials (SCMs), compared to other test methods. The phase 2 work, described in this paper aimed to improve the robustness of the test procedure and to develop precision statements for the consolidated test procedure. The effect of the pre-mixing and mixing conditions, and the impact of the mix design on the test method robustness were assessed and fixed for optimal conditions to carry out the R3 heat release test. The effect of the drying step was evaluated to define the R3 bound water test procedure in more detail. Finally, the robustness of the consolidated final test methods was determined by an interlaboratory study to define the precision statements.

ABSTRACT Research to date into the drivers of public support for participative democracy has offered limited insights into different national contexts. The present article addresses this gap in the literature. It empirically examines the sway of citizens’ appraisal of the state of democracy in the country, their political interest and personal socio-economic positions as well as the objective national socio-economic environment on public attitudes towards direct democracy. Using European Social Surveys (ESS) data, the results in this paper demonstrate that citizens’ political interest explains more about the public attitudes towards direct democracy than citizens’ assessment of the performance of the political regime, institutions and actors, and education. They also show that individuals in countries with integral proportional representation voting systems are more likely to support the use of referendums for key issues than those in countries without such systems. Education and income are found to have only a relatively modest impact on this support. The findings finally suggest that apart from a country’s level of press freedom, no other objective national socio-economic indicator tends to sway popular support for participative democracy. In the light of these findings, implications are drawn.