Influence of physico-chemical characteristics of limestone fillers on fresch and hardened mortar performances

in De Schutter, G.; Boel, V. (Eds.) Self-Compacting Concrete SCC 2007 (2007, September)

In order to meet the specific requirements for fresh Self-Compacting Concrete (SCC), i.e. a high workability together with a good resistance to segregation, the amount of coarse aggregates has to be ... [more ▼]

In order to meet the specific requirements for fresh Self-Compacting Concrete (SCC), i.e. a high workability together with a good resistance to segregation, the amount of coarse aggregates has to be reduced and replaced by fine material. Since cement is quite expensive and can develop a high heat of hydration with possible problems for thermal cracks in massive concrete, mineral fillers are usually used. In Belgium, local available materials are limestone fillers; they are very well-adapted for the optimisation of particle packing and flow behaviour of cementitious paste in SCC mixes. These by-products are issued from different sectors, such as the aggregate and lime production industry (quarrying operations) and the ornamental stones industry (sawing operations). The suitability of these fillers for use in SCC or conventional concrete production was investigated. This paper reports the effect of the nature and the substitution rate of the fillers on the properties of mortars. Some relationship between the physico-chemical properties of the fillers and the properties of mortars were brought forward. [less ▲]

What about concrete in the next thirty years ?

Conference (2007)

On the effect of concrete surface roughness on stress wave propagation in repair systems

in Adhesion in Interfaces of Building Materials: a Multi-Scale Approach (2007)

Concrete removal techniques: influence on residual cracking and bond strength

in Concrete International (2006), 28(12), 49-55

The aim of concrete surface preparation prior to repair is to obtain a surface with properties close to that of the bulk concrete. In this paper, the results of an investigation intended to evaluate the ... [more ▼]

The aim of concrete surface preparation prior to repair is to obtain a surface with properties close to that of the bulk concrete. In this paper, the results of an investigation intended to evaluate the mechanical degradation induced by different surface preparation techniques are presented. Optical microscope observations clearly show that more cracking is induced with jack-hammers than with the other investigated techniques and that the cracking density increases with the hammer weight. While more information is needed to evaluate quantitatively the effects of concrete removal operations, it appears from the reported results that techniques such as sandblasting, scarifying and water jetting are preferable, as they clearly leave much less defects in the substrate. [less ▲]

Mix stability as a criterion for optimizing the granular composition to improve concrete durability – an application

in Marchand, J.; Bissonnette, B.; Gagné, R. (Eds.) et al Advances in Concrete through Science and Engineering (2006, September)

Design of a Self Compacting Repair Mortar to be applied under concrete slabs and floors

in Marchand, J.; Bissonnette, B.; Gagné, R. (Eds.) et al Advances in Concrete through Science and Engineering (2006, September)

Evaluation and quality assessement of industrial floors

in Seidler, Peter (Ed.) Industrial floors (2006)

In the beginning of a project where repair, protection or reinforcement works are planed on industrial floors, the condition of the structure must be inspected and assessed properly. Which kind of ... [more ▼]

In the beginning of a project where repair, protection or reinforcement works are planed on industrial floors, the condition of the structure must be inspected and assessed properly. Which kind of expertise and qualifications are expected from the assessment consultant, depends on the structure, its environment and potential defects. The investigation must be thorough enough to get a reliable picture over the existence, extent, grade, reasons and effects of all significant degradation mechanisms and to assess their progress and effect on the essential requirements that the structure shall meet. The aim of this chapter is to present the general procedures to be followed in order to investigate the common situation of the industrial floors. As the testing procedures are very similar as well for concrete substrate than for overlay evaluation, the principles of the measurement are given hereafter, while the specific applications will be described in chapters 4.2., 4.3. and 4.4. Engineers generally require guidance on both the techniques available for the condition assessment of structures and the methods for data interpretation. Two major stages are usually recommended for such operation. The first stage is based on a rapid-scan visual assessment, often including limited sampling in areas obviously damaged, from which areas can be selected for more detailed investigations. The second stage contains detailed diagnostic survey relies on destructive and non destructive testing techniques. [less ▲]

Effect of concrete substrate texture on the adhesion properties of PCC repair mortar

in Barroso de Aguiar, J.; Jalali, S.; Camoes, A. (Eds.) et al Polymers in Concrete (2006, April)

The study of adhesion of repair materials on concrete structures implies a good knowledge of the influence of concrete surface characteristics. A large research project has been realized with regards to ... [more ▼]

The study of adhesion of repair materials on concrete structures implies a good knowledge of the influence of concrete surface characteristics. A large research project has been realized with regards to the influence of concrete substrate strength and preparation technique efficiency. Three types of concretes and four types of surface preparation have been combined in order to obtain twelve different concrete slabs. They have been characterized according different destructive and non destructive techniques: Schmidt hammer, compressive strength, superficial cohesion (pull-off tests), Impact Echo measurements and cracking quantification (microscopical observations). Finally, a polymer cement concrete mortar has been applied and adhesion has been evaluated by means of pull-off and laboratory tensile tests. The relationships between parameters describing surface quality (roughness, cracking), adhesion strength and stress wave propagation have been analysed. [less ▲]

Durabilité des réparations du béton: entre théorie et pratique

in Arliguie, Ginette (Ed.) Compte-rendu des Journées Scientifiques du (RF)2B (2006)

Le béton est réputé durable. L’expérience de cette durabilité est toutefois fort limitée en termes d’échelle temporelle : nombreux sont les facteurs – internes et externes - qui peuvent amener une ... [more ▼]

Le béton est réputé durable. L’expérience de cette durabilité est toutefois fort limitée en termes d’échelle temporelle : nombreux sont les facteurs – internes et externes - qui peuvent amener une dégradation parfois très rapide du matériau. Fort heureusement, ces dégradations n’ont que très peu souvent d’effet irrémédiable sur le comportement structurel de l’ouvrage en béton. Les réparations permettent en général de prolonger la durée de vie des structures, en réhabilitant le comportement du matériau : l’adhérence du système de protection ou de réparation constitue dans ce cas une condition nécessaire mais pas toujours suffisante. Définir les conditions d’ « appétence » est la première étape du processus : quelles sont les conditions minimales à rencontrer pour que les matériaux « adhèrent », dans un environnement donné ? Ces conditions sont-elles suffisantes pour garantir la durabilité des réparations ? De plus, l’évaluation de l’adhérence pose problème en soi : traction, cisaillement, torsion sont autant de sollicitations censées représenter le comportement réel d’une interface : quel type d’essai employer ? Comment allier facilité et efficacité ? Laboratoire et chantier ? [less ▲]

Evaluation of concrete substrate prior to overlay. Bonded concrete overlays – Recommendations and Applications

Conference (2006)

The knowledge and analysis of the causes of degradations is the first step in repairing existing concrete structures. The assessment is performed by using destructive and non destructive methods. These ... [more ▼]

The knowledge and analysis of the causes of degradations is the first step in repairing existing concrete structures. The assessment is performed by using destructive and non destructive methods. These allow to detect modification of physical, chemical and/or mechanical properties of concrete: cracking, deformation, spalling, carbonation, …etc are various causes of distress, with potential irreversible consequences on concrete structure behaviour. A description of specific methods for pavements and structural slabs is proposed; it is usually recommended to combine complementary methods for efficient diagnosis. This chapter wants to offer an overview of techniques and references that could help the user in selecting the most appropriate investigation program. [less ▲]