4 research outputs found
Time-dependent fibre pull-out behaviour in self-compacting concrete
In the present study, the effectiveness of a fibre as an element for transferring stresses across cracks under a sustained
load was assessed. Single fibre pull-out creep tests were performed, in which fibre slip was monitored as a function
of the time. The influence of the fibre orientation angle (0, 30 and 60 degrees), as well as pre-imposed fibre slip levels,
spr, 0.3 and 0.5 mm on the creep response was investigated. Additionally, instantaneous fibre pull-out tests were carried
out on undamaged-bond specimens in order to quantify the effects of the pull-out creep behaviour. The damage
introduced by the pre-slip levels in the bond of the fibre/matrix interface influenced the long-term fibre pull-out
behaviour and, consequently, accelerated the creep rate. However, the assembled pull-out creep behaviour did not
differ considerably from the instantaneous pull-out behaviour for the adopted pre-imposed fibre slip levels.This work is supported by the FEDER funds through the Operational Program for Competitiveness Factors -
COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the project 18 SlabSys-HFRC-PTDC/ECM/120394/2010. The authors would like to acknowledge the materials supplied by Radmix and Maccaferri (fibres), SECIL (cement), SIKA and BASF (superplasticizers), Omya Comital (limestone filler), and Pegop (Fly ash).info:eu-repo/semantics/publishedVersio
Relation between fibre distribution and post-cracking behaviour in steel fibre reinforced self-compacting concrete panels
In this research, the influence of the fibre distribution and orientation on the post-cracking behaviour of steel fibre
14 reinforced self-compacting concrete (SFRSCC) panels was studied. To perform this evaluation, SFRSCC panels
15 were cast from their centre point. For each SFRSCC panel, cylindrical specimens were extracted and notched either
16 parallel or perpendicular to the concrete flow direction, in order to evaluate the influence of fibre dispersion and
17 orientation on the tensile performance. The post-cracking behaviour was assessed by both splitting tensile tests and
18 uniaxial tensile tests. To assess the fibre density and orientation through the panels, an image analysis technique was
19 employed across cut planes on each tested specimen. It is found that the splitting tensile test overestimates the post20
cracking parameters. Specimens with notched plane parallel to the concrete flow direction show considerable higher
21 post-cracking strength than specimens with notched plane perpendicular to the flow direction.The studies reported in this paper are part of the research project LEGOUSE (QREN, project no 5387). This project is co-supported by FEDER through COMPETE programme ("Programa Operacional Factores de Competitividade"). The materials were supplied by Radmix and Maccaferri (fibres), SECIL (cement), SIKA and BASF (superplasticizers), Omya Comital (limestone filler), and Pegop (Fly ash)
Assessment of different methods for characterization and simulation of post-cracking behavior of self-compacting steel fiber reinforced concrete
The post-cracking tensile properties of steel fiber reinforced concrete (SFRC) is one of the most important aspects that should be considered in design of SFRC structural members. The parameters that describe the post-cracking behavior of SFRC in tension are often derived using indirect methods combined with inverse analysis techniques applied to the results obtained from three- or four-point prism bending tests or from determinate round panel tests. However, there is still some uncertainty regarding the most reliable methodology for evaluating the post-cracking behavior of SFRC. In the present study a steel fiber reinforced self-compacting concrete (SFRSCC) was developed and its post-cracking behavior was investigated through an extensive experimental program composed of small determinate round panel and prism bending tests. Based on the results obtained from this experimental program, the constitutive tensile laws of the developed SFRSCC were obtained indirectly using two numerical approaches, as well as three available analytical approaches based on standards for estimating the stress versus crack width relationship (). The predictive performance of both the numerical and analytical approaches employed for estimating the relationship of the SFRSCC was assessed. The numerical simulations have provided a good prediction of the post-cracking behavior of the concrete. All the analytical formulations also demonstrated an acceptable accuracy for design purposes. Anyhow, among all the employed approaches, the one that considers the results of small determinate round panel tests (rather than that of prism bending tests) has predicted more accurately the constitutive tensile laws of the SFRSCCFEDER funds through the Operational Programme for
Competitiveness and Internationalization - COMPETE and by national funds through FCT (Portuguese Foundation for Science and Technology) within the scope of the project InOlicTower, POCI-01-0145-FEDER520 016905 (PTDC/ECM-EST/2635/2014)