scholarly journals Analysis of the influence of chlorides in the mechanical behaviour of high-performance steel fibre reinforced cementitious composites

2021 ◽  
Vol 4 (1) ◽  
pp. e29
Author(s):  
Mylene De Melo Vieira ◽  
Sergio Henrique P Cavalaro ◽  
Antonio Aguado

Steel fibres are used in high amounts in high-performance steel fibre reinforced cementitious composite (HPSFRCCs) and ultra-high-performance steel fibre reinforced cementitious composite (UHPSFRCCs) to enhance its structural performance. Due to the amount and randomly distribution of steel fibres in the cementitious matrix a level of damage in the aesthetic and mechanical response of fibres may be expected for structures under chloride exposition. This work aims to assess the structural behaviour of uncracked HPSFRCCs subjected to chlorides. Eight mixes of HPSFRCCs with different fibre content (40, 80, 120 and 160 kg/m3), with and without chlorides added to the mixes were designed. Prismatic specimens were cast and exposed to two curing conditions: initially in wet room and then in climatic room. The mechanical properties were obtained by means of the 3-point bending tests. The presence of corrosion in cross-section of the specimens were also analysed after mechanical tests by means of visual inspection. The results showed that the chloride added to the mixes has little influence on the post-cracking response of fibres.

2017 ◽  
Vol 21 (8) ◽  
pp. 1234-1248 ◽  
Author(s):  
Shenchun Xu ◽  
Chengqing Wu ◽  
Zhongxian Liu ◽  
Jun Li

A finite element model is developed to investigate the behaviour of ultra-high-performance steel fibre–reinforced concrete columns under combined axial compression and horizontal monotonic push loading. The effects of steel fibre content, axial compression ratio, reinforcement ratio (or rebar ratio), stirrup ratio and shear span ratio on the structural behaviour of ultra-high-performance steel fibre–reinforced concrete columns are investigated in detail. The numerical model shows good agreement in bond–slip behaviour of specimens based on CEB model results and numerical results, and such behaviour should be taken into consideration in engineering practice. The results indicate that the developed finite element model could predict the structural behaviour and failure mode of ultra-high-performance steel fibre–reinforced concrete columns effectively. It is found that the reinforcement ratio, axial compression ratio, shear span ratio and volume fraction of steel fibre have a great influence on both the structural behaviour and failure modes of specimens.


2021 ◽  
Vol 4 (1) ◽  
pp. e28
Author(s):  
Mylene De Melo Vieira ◽  
Sergio H. P. Cavalaroc ◽  
Antonio Aguado

High-performance steel fibre reinforced cementitious composites (HPSFRCCs) are usually produced with high contents of steel fibres. Therefore, more fibres are expected close to the surface. Despite the very dense matrix of these materials, the ingress of detrimental agents such as chlorides may occur. The objective of this work is to evaluate the mechanisms and effects of corrosion in HPSFRCCs specimens in terms of surface aspect. Eight mixes of HPSFRCCs with different fibre content (40, 80, 120 and 160 kg/m3), with and without chlorides added to the mixes were designed. Prismatic specimens were cast and exposed to two curing conditions: initially in wet room and then in climatic room. Surface aspect was assessed by visual analysis with the use of a classification criteria. Results showed that the chloride added to the mixes induced a damage related to the superficial aspect whereas the specimens without chlorides presented no sign of corrosion over time.


2020 ◽  
Vol 60 (6) ◽  
Author(s):  
Michal Mára ◽  
Radoslav Sovják ◽  
Jindřich Fornůsek

Thin plates made of Ultra-High-Performance Steel-Fibre-Reinforced Concrete (UHPSFRC) with textile Aramid fabrics were subjected to a projectile impact and its post-test damage was discussed. The damage degrees were the type of the response and crater surface, which was determined by using a 3D scanner. The most common type of ammunition, which is a 7.62 × 39mm calibre with a full-metal jacket and a mild-steel core, was used for all specimens. It was verified experimentally that the UHP-SFRC with textile Aramid fabrics has a better ballistic performance in comparison with its counterpart made of the UHP-SFRC without any textile reinforcement. Also, it was verified that specimens with the point or segment interconnection threads between the front side textile fabrics and rear side textile fabrics have a higher resistance due to the better integrity of the monolithic UHP-SFRC mixture.


2016 ◽  
Vol 2 (2) ◽  
pp. 40
Author(s):  
Concepción Río Vega ◽  
Ana Ribas Sangüesa

ResumenLa fachada autoportante de ladrillo cara vista es el resultado de una profunda reflexión sobre las diferentes soluciones de fachada de ladrillo que se han utilizado a lo largo de la historia. Ha sido promovida por Hispalyt en estrecha colaboración con el Departamento Técnico de Geohidrol S.A., empresa líder en la investigación, fabricación y comercialización de sistemas para cerramientos de fábrica. Cuando se analizan las diferentes soluciones de las fachadas de ladrillo, bajo la óptica de los requisitos del Código Técnico de la Edificación, la fachada autoportante 'STRUCTURA' se manifiesta como la solución óptima por su simplicidad, sus elevadas prestaciones y el bajo coste en recursos auxiliares. La fachada autoportante 'STRUCTURA' se caracteriza porque la hoja exterior del cerramiento se construye totalmente separada del edificio, gravitando sobre sí misma, lo cual permite la disposición de una cámara de aire (ventilada o no) con aislamiento térmico continuo. De esta forma se elimina el puente térmico en el encuentro con los frentes de pilares y forjados, mejorando notablemente el rendimiento higrotérmico del edificio con el fin de cumplir el Documento Básico de Ahorro de Energía (DB HE), cuyos requisitos en la nueva versión aprobada en Septiembre de 2013 han experimentado un sustancial incremento respecto de los contenidos en la versión anterior. Desde el punto de vista de la respuesta mecánica, la fachada autoportante se fundamenta en el aprovechamiento del potencial que tienen los muros de ladrillo cuando se utilizan como soportes de sí mismos. A diferencia de las soluciones convencionales o de las que requieren elementos auxiliares de sostén dispuestos planta a planta, con la solución 'STRUCTURA' el muro de ladrillo se analiza como un elemento activo en el comportamiento estructural, de manera que su propio peso contribuye beneficiosamente en la resistencia frente a las acciones horizontales.AbstractThe self-supporting face brick façade is the result of a profound reflection on the different solutions for the brick façades that have been used throughout history. It has been promoted by Hispalyt in close collaboration with the Technical Department of Geohidrol S.A., leader company in the research, manufacture and marketing of systems for masonry closings. When analyzing different solutions of face brick façade, under the perspective of the technical building code requirements, the self-supporting façade 'STRUCTURA' appears as the optimal solution for its simplicity, high performance and low cost in auxiliary resources. The self-supporting façade 'STRUCTURA' is characterised by the outer leaf of the enclosure being built fully separately from the building, supported on itself, and thus enabling the provision of an air chamber (ventilated or not) with continuous thermal insulation. In this manner thermal bridges on the fronts of pillars and floors are eliminated, noticeably improving the hygrothermal performance of the building in order to comply with the technical building code basic document for energy saving (DB HE), whose requirements in the new version approved in September 2013 have substantially increased with respect to the requirements of the previous version. From the point of view of the mechanical response, the self-supporting façade is based on exploiting the potential that brick walls have when used as a load-bearing structural element themselves. Unlike conventional solutions or those that require additional support devices arranged floor-to-floor, with the 'STRUCTURA' solution the brick wall is analyzed as an active element in the structural behaviour, so that its own weight contributes beneficially to the resistance against horizontal actions.


Author(s):  
Benjamin Erzar ◽  
Christophe Pontiroli ◽  
Eric Buzaud

To evaluate the vulnerability of ultra-high performance fibre-reinforced concrete (UHPFRC) infrastructure to rigid projectile penetration, over the last few years CEA-Gramat has led an experimental and numerical research programme in collaboration with French universities. During the penetration process, concrete is subjected to extreme conditions of pressure and strain rate. Plasticity mechanisms as well as dynamic tensile and/or shear damage are activated during the tunnelling phase and the cratering of the concrete target. Each mechanism has been investigated independently at the laboratory scale and the role of steel fibres especially has been analysed to understand their influence on the macroscopic behaviour. To extend the experimental results to the structural scale, penetration tests on UHPFRC slabs have been conducted by CEA-Gramat. The analysis of this dataset combined with material characterization experiments allows the role of steel fibres to be identified in the different plasticity and damage mechanisms occurring during penetration. In parallel, some improvements have been introduced into the concrete model developed by Pontiroli, Rouquand and Mazars (PRM model), especially to take into account the contribution made by the fibres in the tensile fracture process. After a primary phase of validation, the capabilities of the PRM model are illustrated by performing numerical simulations of projectile penetration into UHPFRC concrete structures. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.


Sign in / Sign up

Export Citation Format

Share Document