Time dependent behavior of elements combining ultra-high performance fiber reinforced concretes (UHPFRC) and reinforced concrete

Abstract

Structural elements combining Ultra-High Performance Fiber Reinforced Concretes (UHPFRC) and concrete offer a high potential in view of rehabilitation and modification of existing structures. The investigation of the time-dependent behavior of composite "UHPFRC-concrete" elements is a fundamental step in the determination of durability and serviceability. For this, an experimental program was conducted on large composite "UHPFRC-concrete" beams and a numerical model was validated with the test results. The experimental results and a parametric study performed with the numerical model showed that UHPFRC and normal strength reinforced concrete are compatible in the long-term and that the critical period of composite "UHPFRC-concrete" elements are the first 90 days after the casting of the UHPFRC layer. Thus, the high potential of such composite elements can be exploited also in the long term. Résumé Leséléments structuraux composés de Béton Fibré Ultra Performant (BFUP) et de béton armé offrent un grand potentiel dans la réhabilitation etla modification des structures existantes. L'étude du comportement différé de telséléments composés est indispensable pour déterminer leur durabilité et leur aptitude au service. Une campagne expérimentale aété réalisée sur des poutres mixtes BFUP -béton armé, et un modèle numérique aété validé avec les résultats d'essais. Ces résultats et uneétude numérique avec le modèle numérique montrent que le BFUP et le béton armé sont compatibles sur le bilan déformationnelà long terme et que la période critique deséléments mixtes est les premiers 90 jours après le bétonnage de la couche de BFUP. Ainsi, le potentielélevé de telś eléments mixtes peutêtre exploitéà long terme.

Tensile fatigue behaviour of ultra-high performance fibre reinforced concrete (UHPFRC)

“…Thus, the stress carrying capacity of UHPFRC under tensile fatigue significantly decreases when the material deformation is within the equivalent strain-hardening domain. Habel [15] reported similar findings from cyclic tensile tests on a different UHPFRC mix (CEMTEC multiscale Ó).…”

Ultra-High Performance Concrete: Mechanical Performance, Durability, Sustainability and Implementation Challenges

“…Generally, the reported setting time of UHPC ranged from 6 to 12 h depending on the mixture design (Richard and Cheyrezy 1995;Yoo et al 2013;Kazemi and Lubell 2012). However, some studies (Brown 2006;Graybeal 2007;Habel 2004;Morin et al 2001) showed that the setting time for UHPC can be delayed for up to 30-40 h due to the set retarding effect of high SP dosage. Furthermore, it was observed that surface covering of freshly mixed UHPC delayed its setting time (Yoo et al 2013).…”

Separation of thermal and autogenous deformation at varying temperatures using optical fiber sensors

“…Mould M3 was used for a test in a thin layer of special repairing mortar made of high performance fibre-reinforced cement-based material (UHPFRC) [29]. The testing of this material posed particular challenges.…”