Pourchez J.,Granular |
Grosseau P.,Granular |
Ruot B.,Scientific and Technical Center for Building
Cement and Concrete Research | Year: 2010
The influence of cellulose ethers (CE) on C3S hydration processes was examined in order to improve our knowledge of the retarding effect of cellulose ethers on the cement hydration kinetics. In this frame, the impacts of various cellulose ethers on C3S dissolution, C-S-H nucleation-growth process and portlandite precipitation were investigated. A weak influence of cellulose ethers on the dissolution kinetics of pure C3S phase was observed. In contrast, a significant decrease of the initial amount of C-S-H nuclei and a strong modification of the growth rate of C-S-H were noticed. A slowing down of the portlandite precipitation was also demonstrated in the case of both cement and C3S hydration. CE adsorption behavior clearly highlighted a chemical structure dependence as well as a cement phase dependence. Finally, we supported the conclusion that CE adsorption is doubtless responsible for the various retarding effect observed as a function of CE types. © 2009 Elsevier Ltd. All rights reserved.
Pourchez J.,Granular |
Ruot B.,Scientific and Technical Center for Building |
Debayle J.,Granular |
Pourchez E.,Granular |
Cement and Concrete Research | Year: 2010
This paper evaluates and compares the impact of cellulose ethers (CE) on water transport and porous structure of cement-based materials in both fresh and hardened state. Investigations of the porous network (mercury intrusion porosimetry, apparent density, 2D and 3D observations) emphasize an air-entrained stabilisation depending on CE chemistry. We also highlight that CE chemistry leads to a gradual effect on characteristics of the water transport. The global tendencies brought by CE are: higher water retention, lower capillarity water absorption, lower liquid water permeability as well as higher water vapour permeability. All things considered, we demonstrate that CE chemistry is an important controlling factor on water transport and porous structure evolution. © 2009 Elsevier Ltd. All rights reserved.
Bluyssen P.M.,Technical University of Delft |
Roda C.,Technical University of Delft |
Mandin C.,Scientific and Technical Center for Building |
Fossati S.,University of Milan |
And 5 more authors.
Indoor Air | Year: 2016
In the European research project OFFICAIR, a procedure was developed to determine associations between characteristics of European offices and health and comfort of office workers, through a checklist and a self-administered questionnaire including environmental, physiological, psychological, and social aspects. This procedure was applied in 167 office buildings in eight European countries (Portugal, Spain, Italy, Greece, France, Hungary, the Netherlands, and Finland) during the winter of 2011-2012. About 26 735 survey invitation e-mails were sent, and 7441 office workers were included in the survey. Among respondents who rated an overall comfort less than 4 (23%), 'noise (other than from building systems)', air 'too dry', and temperature 'too variable' were the main complaints selected. An increase of perceived control over indoor climate was positively associated with the perceived indoor environment quality. Almost one-third of office workers suffered from dry eyes and headache in the last 4 weeks. Physical building characteristics were associated with occupants' overall satisfaction (acoustical solutions, mold growth, complaints procedure, cleaning activities) and health (number of occupants, lack of operable windows, presence of carpet and cleaning activities). OFFICAIR project provides a useful database to identify stressors related to indoor environmental quality and office worker's health. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Lamoulie J.,FCBA Technological Institute |
Pompeo C.,Scientific and Technical Center for Building |
Garnier G.,Scientific and Technical Center for Building
10th International Conference on Healthy Buildings 2012 | Year: 2012
Timber frame walls are composed of at least eight layers, each one with different properties concerning water vapour diffusion. The objective of this study is to identify the timber frame walls compositions where moisture transfer is maximum and the likelihood of mould near zero. The variable parameters of the study are: indoor and outdoor climates, design walls, vapour permeability of wood-based panels, of rain-barrier and vapour-barrier, nature and thickness of insulation materials. 157 designs walls were analyzed. The likelihood of mould was checked with a methodology created specifically to control moisture conditions at the interface between the wall components and in the components themselves. This methodology is based on the kinetics of development of mould fungi. The most influential parameters are: position of the bracing panel, position, nature and thickness of the insulation material and the ratio of vapour permeability between the inside and the outside face.
Bourdic L.,Scientific and Technical Center for Building |
Salat S.,Scientific and Technical Center for Building
Building Research and Information | Year: 2012
Understanding how and why cities and the urban fabric contribute to energy consumption and greenhouse gas (GHG) emissions is a crucial issue regarding climate change and resource scarcity. A critical review is presented of the calculation tools, models, and assessment systems that deal with energy consumption and GHG emissions from buildings at the district and city scales. The review encompasses international assessment systems and technical models developed in Japan, North America and Europe. The relationships and connections between policy and research within these systems are examined. Chronic systemic failures are highlighted that should be addressed rapidly in the research agenda. The negative impacts are considered in terms of the operational potential due to the use of rough aggregation methods. The analysis emphasizes the need for more systemic, multi-scale and transverse approaches to deal with the intrinsic complexity of the urban fabric. Four intervention points for urban efficiency are proposed: urban morphology, buildings' efficiency, systems' efficiency and individual behaviours. Harnessing all of these would improve the potential of models and assessment systems. Combining these urban efficiencies would have a multiplier effect in terms of actual outcomes in reducing energy consumption. © 2012 Taylor & Francis.