ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

Showing 1-5 of 783 Abstracts search results

Document: 

SP-343_39

Date: 

October 1, 2020

Author(s):

Zanotti, C.; Randl, N.; Gar, P.S.; Far, B.K.; Steiner, M.

Publication:

Symposium Papers

Volume:

343

Abstract:

Fiber Reinforced Concrete (FRC) is being increasingly applied in structural repair and retrofit of reinforced concrete structures. Not only fiber reinforcement improves the durability of reinforced concrete structures, but it also enhances compatibility of the repair material to the existing structure, further enhancing structural effectiveness and service life of the intervention. Furthermore, studies have shown that fiber reinforcement can significantly improve substrate-repair bond in both tension and shear. However, this benefit is not fully utilized in repair/retrofit design due to test uncertainties and lack of comprehensive data on correlations with other fundamental factors. In this study, the question of the appropriateness, reliability and sensitivity of current bond tests in case of FRC repairs is addressed. Several tension and shear bond tests on plain and fiber reinforced cement-based repairs are performed in parallel by two research teams at UBC (Canada) and CUAS (Austria), following a rigorous testing procedure to allow consistency among results from the two laboratories. The influence of repair strength and casting direction is also investigated. The effect of fiber reinforcement on bond is assessed while correlation, comparability, and sensitivity of different test set-ups and stress conditions are discussed.


Document: 

SP-343_24

Date: 

October 1, 2020

Author(s):

Bernard, E. S.

Publication:

Symposium Papers

Volume:

343

Abstract:

Numerous investigations of the effect of fibre addition on the seismic performance of conventionally reinforced concrete members have been published. These generally show that fibres can improve robustness and survivability during reverse-cycle loading, but the dosage rate of fibre required to achieve significant improvements in performance is substantial. Recently, pure FRC members have increasingly been used in structures such as tunnel linings, including both fibre reinforced shotcrete and pre-cast FRC segments. Concerns have been raised about the absence of data on the seismic resistance of such members given that all previous research on seismic performance has essentially involved hybrid members incorporating both steel reinforcing bars and fibres. The present investigation has focused on the reverse-cycle flexural performance of FRC members in the absence of conventional steel reinforcing bars. Laboratory testing was performed on plain, bar-reinforced, and steel fibre reinforced concrete members, and their performance was compared. The tests indicate that steel fibres provide a small improvement in flexural capacity under reverse-cycle loading compared to plain concrete, but that the robustness of pure FRC members is relatively poor compared to steel bar-reinforced members incorporating steel stirrups. The data suggest that, when used at practical dosage rates, large hooked-end steel fibres cannot be relied upon to provide seismic performance in flexure comparable to steel bar reinforced concrete members.


Document: 

SP-343_07

Date: 

October 1, 2020

Author(s):

Javadian, A.; Mahdavi, A.; Benamrane, O. ;Majeed, M.; Aoude, H.

Publication:

Symposium Papers

Volume:

343

Abstract:

This study examines the effect of fiber properties, single fiber type and hybrid fibers on the fresh-state and hardened-state properties of self-consolidating fiber-reinforced concrete (SCFRC). As part of the study, 16 mixtures are examined with variables including the effect of fiber type, length, aspect ratio, and hybrid use of fibers (short and long fibers). Properties in the fresh state are studied using standard SCC tests including: slump flow, V-funnel and visual stability index (VSI) tests. Mechanical properties are studied by testing prisms under four-point flexural loading in accordance with the ASTM C1609 standard. The results demonstrate that self-consolidating FRC mixtures are possible at moderate fiber contents, however, once the limiting fiber contents are exceeded workability and mix uniformity are lost. The results also show the effects of fiber content, fiber type, fiber properties and hybrid fibers on the flexural toughness of SCFRC.


Document: 

SP-343_08

Date: 

October 1, 2020

Author(s):

Chelha, F.; Alam, S. Y.; Bendimerad, A.Z.; Loukili, A.

Publication:

Symposium Papers

Volume:

343

Abstract:

Self-compacting mortars and concretes for horizontal structures are cementitious mixtures that are both fluid and homogeneous, with the particularity of flowing under the effect of their own weight. Thanks to their homogeneous texture they offer the possibility of achieving good quality of finishing and many such advantages become the reason for their applications especially in slabs and floors. However, self-compacting mortars or concretes show considerable shrinkage and cracking problems when used in floors and slabs (Weiss et al., 1998). Because of their large moisture exchange surfaces, the floor screeds are subjected to significant drying effects and in particular plastic shrinkage. If the movements are restrained, the risk of cracking is high. In this respect the use of fibers is a good alternative to using reinforcement bars and welded wire mesh. Indeed on site a clear decrease in cracking caused mainly by the shrinkage can be observed as soon as the fibers are incorporated in the screed. This study is conducted to demonstrate the effectiveness and the effects of glass fibers on the control of cracking phenomena due to shrinkage by determining their mechanisms of action at young age. The study is carried out in two parts: Firstly, free shrinkage behavior is analyzed in the fiber reinforced floor screed. Secondly, the restrained behavior at young ages using recently developed uni-axial tensile testing machine is investigated.


Document: 

SP-343_06

Date: 

October 1, 2020

Author(s):

Juhasz, K.P.; Schaul, P.; Winterberg, R.

Publication:

Symposium Papers

Volume:

343

Abstract:

The design of fibre reinforced shotcrete (FRS) hard rock linings is commonly based on the Q-System or Barton charts. This performance based design approach assess the results of experimental tests, carried out on panel specimens according to existing standards or guidelines. This is different to the general methodology to assess and determine the performance of fibre reinforced concrete (FRC) using standardized beam tests. Panel and beam test results yield significantly different information on the performance of FRC and it is problematic to correlate them. The beam test yields a stress-strain relationship for a small displacement range only. Based on the significantly different working and failure mechanisms, structural tests to evaluate the post-crack performance and the ductility of FRS linings are typically conducted on different types of panels rather than on traditional beams. As a consequence, test results based on beam tests may lead to an overestimation of FRC performance in panels and vice versa. In order to avoid uneconomic designs the most appropriate material must be found using the most appropriate test methodology. This paper discusses the difficulty in correlating test results obtained from beams and panels as well as the discrepancy in performance of different FRC using different test methodologies and aims to provide guidance on materials, testing and design.


12345...>>

Results Per Page 




Please enter this 5 digit unlock code on the web page.