Publications internationales
Résumé: The main objective of this paper is to compare the fracture toughness determined by instrumented indentation tests of a variety of self-compacting concretes (SCCs) and normal vibrated concretes (NVCs). For this purpose, five mixing compositions of self-compacting concrete (SCC) with different water/binder ratios of 0.33 to 0.41 (water/cement ratio = 0.44 to 0.56) and two mixing compositions of normal vibrated concrete (NVC) were prepared. The fracture behaviors of both (SCCs) and (NVCs) with laboratory-size specimens under the instrumented indentation test (IIT) were investigated. It was found that the fracture toughness values of the self-compacting concrete increased with the decreasing w/b ratio. The largest values of the stress intensity factor (KIC) were showed on the concretes with the lowest (w/b) ratio (w/b = 0.33, the case of SCC5). Moreover, it is confirmed that the self-compacting concretes exhibit …
Résumé: To ensure reinforced concrete bars applications in more severe loading conditions, the contact between the steel bar and concrete must be strongly adhesive. This adhesion constitutes an important property for the use of reinforced concrete. That is why many techniques were developed with the aim of determining this property. Adhesion can be easily found out by standard pull-out test machine. However, in this work, the adhesion was measured for the first time using Interfacial Indentation test. In this work, given the lack of results obtained using the interfacial indentation test in the literature so that we can compare our results with, the alone alternative found is to compare them with those of the pull out test. Using reinforcing bars, adhesion was measured using Self Compacting Concrete (SCC) and Normal Vibrated Concrete (NVC) specimens. The impact of water-to-binder ratio variations and concrete type on steel …
Résumé: The interfacial indentation test is experimented for the first time in order to characterize the adhesion between the concrete and its steel reinforcement. This technique, developed to estimate the adhesion of thick coatings (thermal barrier, plasma torch deposits, etc.), is used here to create and propagate a crack along the concrete/reinforcement interface. The length of this crack makes it possible to calculate an apparent interfacial toughness which can then be linked to the concrete/reinforcement adhesion, and therefore to the resistance of the elaborate structure. The mechanical properties, hardness and Young's modulus of the various constituents were determined from indentation tests, and micro cracks at the concrete/reinforcement interface are generated by Vickers macro-hardness tests using indentation loads ranging from 300 to 1200 N. The properties of three concretes are compared: a high-performance vibrated concrete HPVC (VC54) and two high-performance self-compacting concretes HPSCCs (SCC54 and SCC62), both developed in the laboratory. The adhesion in terms of apparent interfacial toughness of (SCC54) was found to be greater by 9.17% than that of (VC54) with the same compressive strength. This improvement in bond behavior of SCC against that of vibrated concrete (VC) can be attributed to the higher amount of fine aggregates and higher workability, which results in a better containment of the reinforcement bars. The results obtained by this test are in agreement with those of conventional pull-outs tests while being easier to realize, and we propose its use in order to characterize the adhesion between the concrete and …