Ngo T.T.,Cergy-Pontoise University |
Kadri E.H.,Cergy-Pontoise University |
Bennacer R.,Cergy-Pontoise University |
Cussigh F.,VINCI Construction France
Construction and Building Materials | Year: 2010
The friction at the steel-concrete interface (on the boundary layer) which occurs when concrete flows in a drain plays an important role in its pumpability. This friction is directly related to the composition of the formed boundary layer, which depends on the concrete composition parameters. In order to highlight the relationship between concrete composition and interface friction, the authors initially developed and validated an apparatus (called "tribometer") allowing steel-concrete interface friction measurements and deduce interface parameters. It is simple to use at building sites. The paper highlights the rigorous relationship between the boundary layer (BL) composition and the concrete composition. The results show that the BL is formed by water, cement and fine sand particles of concrete with a diameter lower than 0.25 mm. It was also shown that the water-cement ratio of the BL and that of the concrete are almost the same. The relative enrichment of fine sand in the BL decreases with the increase of the fine sand voluminal proportion in the concrete. © 2009 Elsevier Ltd. All rights reserved.
Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: ENV.2009.3.1.5.2 | Award Amount: 2.60M | Year: 2010
The project will develop 1) sustainability indicators for buildings, 2) understanding about the needed performance levels considering new and existing buildings, different building types and local requirements, 3) methods for the benchmarking of sustainable buildings (SB) and 4) recommendations for the effective use of benchmarking systems as instruments of steering and in building processes. The work will make use of the existing knowledge of SB assessment and rating systems. However, the project recognises that there are still unsolved issues and areas with no common understanding. These include: a) the integration of social and economic issues with SB assessment, b) consideration of certain environmental aspects as land use, c) defining appropriate performance levels considering both minimal levels and advanced targets, d) consideration of local conditions, different building types, and both new and existing buildings when selecting performance levels, d) selection of benchmarking criteria to be easily adopted in different parts of Europe, e) effective mobilisation of the benchmarking system, f) effective making use of the system in building processes and in building regulation and steering. The work will be divided into 8 work packages: WP1 ensures the effective work progress and the good communication between project members and between the project and the Commission; WP2 establishes the common starting point for the project; WP3 analyses the potential of SB benchmarking systems as an instrument of steering and when used in different phases of building projects, WP4 develops and selects sustainability indicators that describe the environmental, social and economic performance of buildings. WP4 will focus on the development of data validity and reliability for each key indicator. WP5 defines performance levels and benchmarking criteria, WP6 makes recommendations for effective exploitation, WP7 pilots the system, and WP8 disseminates the outcomes with help of the project NETWORK GROUP and with help of powerful organisations of building professionals.
Ngo T.-T.,Cergy-Pontoise University |
Kadri E.-H.,Cergy-Pontoise University |
Cussigh F.,VINCI Construction France |
Bennacer R.,Ecole Normale Superieure de Cachan
European Journal of Environmental and Civil Engineering | Year: 2012
Concrete pumpability is determined by the friction at the interface between the concrete and the wall of the pumping pipes (which are generally made of steel); called the concrete-steel interface. This friction is related directly to the thickness and composition of the boundary layer (BL) that occurs during the movement of fresh concrete in a pipe. These BL characteristics are rigorously linked with concrete composition parameters. To highlight this complicated relationship, an apparatus called a 'tribometer' was used in two experimental programs. This apparatus allows measurement of the steel-concrete interface friction and deduction of interface parameters (also called the pumping parameters), namely viscous constant and interface yield stress. The first program focuses on the effect of the concrete composition on pumping parameters, and the second program focuses on the relationships between the concrete composition and the BL composition. The results of the first program show that increases in cement paste volume, water/cement ratio and superplasticiser dosage enhance concrete pumpability. Increased content of fine sand in concrete induces negative effects on the interface frictions and on the pumpability. The results of the second program show that the BL is formed by water, cement and fine sand particles with a diameter lower than 0.25 mm. It also shows that the proportions of water and cement volume in BL and micro-concrete (concrete with the largest grain diameter lower than 0.25 mm) are almost the same. The relative enrichment produced by fine sand in the BL decreases with increasing proportion of fine sand volume in the concrete.
Agency: Cordis | Branch: H2020 | Program: RIA | Phase: MG-5.2-2014 | Award Amount: 3.24M | Year: 2015
Currently freight transport represents 40% of the total transport emission and 32% in urban area. Many initiatives are under development to reduce costs and negative impact of freight and service trip in urban area. Some of them concern supply chain improvements and more specifically consolidation centre projects. Few study cases are dedicated to construction industry. However, urban population tends to grow, increasing the need to develop and reconstruct urban centres. Construction material logistic impact in urban area will intensify in terms of costs and negative impacts in urban area. Yet, only few experiences of Construction Consolidation Centres can be found. Among these initiatives, four are construction site specific (Stockholm, Utrecht, Berlin, London Heathrow) and only one is dedicated to several construction projects (London CC). Theses pilots studies have demonstrated reduced transportation impacts, positive effects on transportation efficiency and construction site productivity. Several limitations to the transferability of this concept are identified: one on hand the demonstrators were implemented in specific contexts (regulatory incentives, cities investment contribution, and specifics transport and logistics infrastructure issues) which are not the same in France, Spain, Italy and Luxembourg. On the other hand, economic viability has not been demonstrated. The project addresses the different requirements for transferability of supply chain optimization concepts as well as CCCs and new ways of working between supply chain stakeholders. The approach is to identify an integrated collaborative approach and business model among construction supply chain actors. Three main steps will be performed: analyse the current issues along the construction supply chain, propose several optimization scenarios regarding these issues, simulate and analyse costs optimization and environmental impacts to propose new partnership opportunities based on savings distribution
Lataste J.F.,University Bordeaux1 |
De Larrard T.,Ecole Normale Superieure de Cachan |
Benboudjema F.,Ecole Normale Superieure de Cachan |
Semenadisse J.,VINCI Construction France
European Journal of Environmental and Civil Engineering | Year: 2012
This article presents electrical resistivity measurement on concrete. The first part presents the study of a lighter protocol for measuring electrical resistivity, allowing investigations of a large number of specimens, without degradation of the quality of final results. The second part is based on measurements made on two concretes cast regularly during one year each, on two sites. Measurements done to assess the different variability sources distinguish variability linked to the measurement of those related to the material. The third part of the article compares the laboratory measurements to those made on site. Finally, all the results reflected the interests of the resistivity measurement because of low variability obtained, and consistency between results. © 2012 Taylor & Francis.