Amélioration et renforcement des bétons

Learning material (2010)

Mechanical and durability properties of concrete using contaminated recycled aggregates

in Cement & Concrete Composites (2010), 32(6), 421-426

The degradation of concrete structures due to chlorides and sulphates penetration is of obvious importance in civil engineering as having major impact on structural durability. In this paper, the results ... [more ▼]

The degradation of concrete structures due to chlorides and sulphates penetration is of obvious importance in civil engineering as having major impact on structural durability. In this paper, the results of an investigation on the effect of contaminated crushed concrete aggregates on mechanical properties and durability of recycled concrete are presented. Natural aggregates concrete (NC) slabs were cured in water, sea water, chloride solutions or sulphate solutions and then crushed to obtain virgin and contaminated (polluted) recycled aggregates. The properties of natural (NA) and recycled aggregates (RA) and the mechanical properties and durability performances of a new concrete made from 100% of RA are analysed. The results show that contaminated RA are much sensitive to chlorides than sulphates and are rapidly leached when soaked into water. Significant differences were observed between the properties of original and new concrete and the results clearly show the necessity of taking these contaminations into account. [less ▲]

Combination of mechanical and optical profilometry techniques for concrete surface roughness characterization

in Magazine of Concrete Research (2009), 61(6)

Achieving durable bond between new and old concrete still represents a challenge in concrete repair technology. It has been the subject of a number of investigations, but in most cases, only adhesion ... [more ▼]

Achieving durable bond between new and old concrete still represents a challenge in concrete repair technology. It has been the subject of a number of investigations, but in most cases, only adhesion strength was addressed. To better understand bond mechanisms, in particular those related to surface roughness, two complementary surface characterisation techniques were implemented, providing a multiscale roughness characterisation by means of specific filtering calculations: mechanical profilometry for low-scale roughness and optical profilometry for the upscale roughness. Using these complementary approaches, different types of concrete surface preparation were characterised. The resulting description highlights the complexity of concrete surface topography. Moreover, it shows that the type of surface preparation essentially affects the meso- and macro-roughness levels, microroughness being practically insensitive. Such results will be useful for better understanding the interlocking potential and bond performance of concrete repairs. [less ▲]

Le béton apparent: influence de l'état du moule sur l'aspect des surfaces

in Benboudjema, Farid (Ed.) Compte-rendu des Journées Scientifiques du (RF)2B (2009)

L’aspect d’un parement en béton (teinte et bullage) dépend entre autres de la surface de coffrage utilisée. L’influence du nombre de réutilisations des coffrages sur la teinte et le bullage de surface a ... [more ▼]

L’aspect d’un parement en béton (teinte et bullage) dépend entre autres de la surface de coffrage utilisée. L’influence du nombre de réutilisations des coffrages sur la teinte et le bullage de surface a été étudiée. Deux séries de moules en bois contreplaqué et OBS ont été usés afin de simuler de 1 à 118 réutilisations pour le contreplaqué et de 2 à 51 réutilisations pour le bois OSB. Les moules ont ensuite été utilisés pour couler des cubes de béton. La première série a été coulée en utilisant une huile végétale et la deuxième une huile minérale. La teinte et le bullage en surface des bétons coulés ont été mesurés et étudiés au travers d’une étude statistique afin de déterminer l’influence de la réutilisation des coffrages sur l’aspect des parements. [less ▲]

Use of concrete road recycled aggregates for Roller Compacted Concrete

in Construction & Building Materials (2009), 24((3)), 390-395

Construction waste management is a quite important economical and environmental deal for our societies. More than 2 million tons demolition and construction wastes are annually produced only in Wallonia ... [more ▼]

Construction waste management is a quite important economical and environmental deal for our societies. More than 2 million tons demolition and construction wastes are annually produced only in Wallonia, Southern Region of Belgium; recycling has clearly to be promoted. Roller Compacted Concrete (RCC) is a special dry concrete made of aggregates, water and low quantity of cement, laid down and compacted like a soil, for the construction of massive structures like dams or large horizontal surfaces like road foundations. The topic of this research is the replacement of natural aggregates by concrete road recycled aggregates in the mix design of concrete. Characteristics of aggregates are of prime importance for the quality of the concrete: Los Angeles, water absorption and specific gravity. It has been observed that RCC with natural and concrete road recycled aggregates are similar for solid compactness, while no major influence of cement content – when around 200 kg - may be detected. However, compressive strength is higher for RCC with natural aggregates. This study clearly shows the opportunity of using concrete road recycled aggregates for RCC in basements. [less ▲]

Recherches menées à l'Université de Liège dans le domaine du béton en 2008-2009

Conference given outside the academic context (2009)

Composite steel-concrete columns made of CFSHS filled with self compacting concrete under ambaint temperature and in the fire situation. Design equation for the buckling of high strength concrete columns ... [more ▼]

Composite steel-concrete columns made of CFSHS filled with self compacting concrete under ambaint temperature and in the fire situation. Design equation for the buckling of high strength concrete columns subkected to compression and bending. Improvement of the textural quality of concrete with hydraulic binders. Influence of the reutilisation of OSB panels shuttering on the colour and texture of concrete surfaces. Non destructive methods for the detection of delamination in the decks of concrete bridges [less ▲]

Znaczenie inżynierii powierzchni w naprawach betonu

in Kaminski, M.; Jasiczak, J.; Buczkowski, W. (Eds.) et al Współczesne metody naprawcze w obiektach budowlanych (2009)

Recently, an efficiency of concrete repair is treated as the civilizing challenge. This was also the genesis to elaborate family of European standards EN 1504. The part 10 of this standard gives ... [more ▼]

Recently, an efficiency of concrete repair is treated as the civilizing challenge. This was also the genesis to elaborate family of European standards EN 1504. The part 10 of this standard gives requirements for substrate condition before and during application including structural stability, storage, the preparation and application of products and systems for the protection and repair of concrete structures including quality control, maintenance, health and safety, and the environment. According to this standard a suitable preparation of concrete substrate prior a repair is considered as the one of the important factors affecting durability of concrete repair. Recently, experiences in this filed is ordered in the framework of scientific approach called concrete surface engineering. The main goal of this approach is analysis of qualitative and quantitative relationships between surface quality and repair durability. The aim of this paper is to analyze an effect of surface treatment on surface quality and adhesion in repair system using concrete surface engineering approach. [less ▲]

Correlation between the roughness of the substrate surface and the debonding risk

in Alexander, M. G.; Beushausen, H.-D.; Dehn, F. (Eds.) et al Concrete Repair, Rehabilitation and Retrofitting II (2009)

This paper presents the influence of substrate surface preparation on the adhesion strength of repaired beams system. Bond between new and old concrete has been the subject of a number of investigations ... [more ▼]

This paper presents the influence of substrate surface preparation on the adhesion strength of repaired beams system. Bond between new and old concrete has been the subject of a number of investigations, but in most cases, only adhesion strength was addressed. This parameter was used to estimate the durability and/or the debonding risk for repaired structure and it’s a generally accepted auditing standards. Usually, surface preparation of the substrate concrete is considered essential to achieve a durable repair because of its influence on the bond strength. To better understand debonding mechanism, in particular these related to surface preparation, roughness parameters were calculated to quantify the influence of surface preparation on the structural behaviour. Using this approach, repair beams prepared by way of four (4) concrete surface preparations were characterized. Results obtained show that repaired beams presenting a substrate with a rough surface permit to achieve a monolithic behaviour of the repaired system. Opposite structural behaviour, with large debonding, was recorded for those having smooth surface. However, all surface preparations used have promoted the same bond strength regardless the roughness of the substrate. The resulting analysis highlights the relation between roughness parameter αrough and the debonding mechanism of repaired beams. Such results will be useful to better predict the performance of concrete repairs. [less ▲]

Aesthetic evaluation and control of concrete building surfaces

in Eterradossi, O. (Ed.) Materials and Sensations 2008 Proceedings (2008, October)

Application du concept de performance équivalente aux bétons additionnés de fillers calcaires

in Annales du Bâtiment et des Travaux Publics (2008), 3

The European standard EN 206-1 integrates the concept of the k-coefficient that allows to take into account the addition of pozzolanic and hydraulic fine materials in order to respect the requirements ... [more ▼]

The European standard EN 206-1 integrates the concept of the k-coefficient that allows to take into account the addition of pozzolanic and hydraulic fine materials in order to respect the requirements concerning the formulation of concrete for the chosen environment. Some national application documents extend this concept to other types of mineral additives such as limestone fillers. In Belgium this principle is not applied yet. Within the scope of the current study, limestone fillers coming from different activity sectors in the Walloon Region (production of aggregates, lime or ornamental stones) were selected. Their influence on the consistency of concrete, its mechanical properties and its long-term behaviour (water-porosity, air permeability and carbonation resistance) was evaluated. [less ▲]