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International Concrete Abstracts Portal

Showing 1-5 of 131 Abstracts search results

Document: 

SP345

Date: 

February 19, 2021

Author(s):

ACI Committee 549

Publication:

Symposium Papers

Volume:

345

Abstract:

Sponsors: ACI Committee 549, Rilem-MCC Editors: Barzin Mobasher and Flávio de Andrade Silva Several state-of-the-art sessions on textile-reinforced concrete/fabric-reinforced cementitious matrix (TRC/FRCM) were organized by ACI Committee 549 in collaboration with RILEM TC MCC during the ACI Fall 2019 Convention in Cincinnati, OH, and the ACI Virtual Technical Presentations in June 2020. The forum provided a unique opportunity to collect information and present knowledge in the field of TRC and FRCM as sustainable construction materials. The term TRC is typically used for new construction applications whereas the term FRCM refers to the repair applications of existing concrete and masonry. Both methods use a textile mesh as reinforcement and a cementitious-based matrix component and, due to high tensile and flexural strength and ductility, can be used to support structural loads. The technical sessions aimed to promote the technology, and document and develop recommendations for testing, design, and analysis, as well as to showcase the key features of these ductile and strong cement composite systems. New methods for characterization of key parameters were presented, and the results were collected towards the development of technical and state-of-the-art papers. Textile types include polymer-based (low and high stiffness), glass, natural, basalt, carbon, steel, and hybrid, whereas the matrix can include cementitious, geopolymers, and lightweight matrix (aggregates). Additives such as short fibers, fillers, and nanomaterials were also considered. The sessions were attended by researchers, designers, students, and participants from the construction and fiber industries. The presence of people with different expertise and from different regions of the world provided a unique opportunity to share knowledge and promote collaborative efforts. The experience of an online technical forum was a success and may be used for future opportunities. The workshop technical sessions chairs sincerely thank the ACI staff for doing a wonderful job in organizing the virtual sessions and ACI TC 549 and Rilem TC MCC for the collaboration.


Document: 

SP-345_12

Date: 

February 1, 2021

Author(s):

Xingxing Zou, Chris Moore, and Lesley H. Sneed

Publication:

Symposium Papers

Volume:

345

Abstract:

Externally bonded (EB) steel reinforced grout (SRG) composites have the potential to improve the flexural and shear performance of existing concrete and masonry structural members. However, one of the most commonly observed failure modes of SRG-strengthened structures is due to composite debonding, which reduces composite action and limits the SRG contribution to the member load-carrying capacity. This study investigated an endanchorage system for SRG strips bonded to a concrete substrate. The end anchorage was achieved by embedding the ends of the steel cords into the substrate. Nineteen single-lap direct shear specimens with varying composite bonded lengths and anchor binder materials were tested to study the effectiveness of the end-anchorage on the bond performance. For specimens with relatively long bonded length, the end-anchorage slightly improved the performance in terms of peak load achieved before detachment of the bonded region. Anchored specimens with long bonded length showed notable post-detachment behavior. Anchored specimens with epoxy resin achieved load levels significantly higher than the peak load before composite detachment occurred. For specimens with relatively short bonded length, the end-anchorage provided a notable increase in peak load and global slip at composite detachment. A generic load response was proposed for SRG-concrete joints with end anchors.


Document: 

SP-345_7

Date: 

February 1, 2021

Author(s):

Houman Hadad, Davide Campanini, and Antonio Nanni

Publication:

Symposium Papers

Volume:

345

Abstract:

Fabric Reinforced Cementitious Matrix (FRCM) is an established technology for strengthening and rehabilitation of existing concrete and masonry structures. In the United States, material characterization of the FRCM composites is in accordance with ICC-ES acceptance criteria AC434. The acceptance criteria recommend tensile testing the FRCM coupons with clevis-grips to obtain the mechanical properties for design purposes. The current test method, however, neglects some of the critical factors affecting the test outcome such as the effect of bonded length or number of fabric layers. The effect of bonded length on the FRCM properties tested per AC434 Annex-A is discussed in this paper. Carbon-FRCM coupons of 2, 3, 6, 9, and 12 inches (50.8, 76.2, 152.4, 228.6, and 304.8 mm) bonded length were prepared and tested in direct tension. The other test variable was the number of fabric layers. The tests were conducted with one- and two-layer fabrics for different bonded length. The results discussed in terms of ultimate stress, ultimate strain, and modulus show that the material characterization of the FRCM composites depended on the bonded length and number of fabric layers of the tested specimens. Moreover, the effect of number of fabric layers on the material characteristics was more pronounced in specimens with shorter bonded length. The experimental results are used to make suggestions for improving the FRCM characterization test methods as currently stated in AC434.


Document: 

SP-345_11

Date: 

February 1, 2021

Author(s):

Maria Antonietta Aiello and Alessio Cascardi

Publication:

Symposium Papers

Volume:

345

Abstract:

The increasing interest in the field of conservation of existing masonry structures pushed to the development of new retrofitting technologies in the recent past. One of the most promising is the use of Fabric Reinforced Cementitious Mortar (FRCM), which consists of an open-grid within an inorganic matrix. The effectiveness of the FRCM-application is well-demonstrated in literature by several experimental investigations regarding different structural members, including columns and shear wall. The success of FRCMs is manly related to durability aspects, since the grid is generally non-metallic, the compatibility of the inorganic matrix with the substrates, the easy application, the low weight and spatial impact, the possible installation in damp areas and at high temperatures. The interaction between the substrate, the mortar-based matrix and the open-grid make challenging the theoretical prediction of the mechanical behavior of the FRCM-retrofitted structures. For this reason, the analytical formulations for the proper design of FRCM-strengthening are still an open research problem, referring to both short and long term conditions. The present paper reports and discusses design-oriented relationships for FRCM-confinement and in-plane FRCM-strengthening of masonry elements; the proposals are intended to satisfy the requirements of simplicity and accuracy needed for code-finality.


Document: 

SP-345_03

Date: 

February 1, 2021

Author(s):

Catherine (Corina) Papanicolaou and Thanasis Triantafillou

Publication:

Symposium Papers

Volume:

345

Abstract:

In this paper, authors draw information from previous work aiming at contributing to: (i) a summary of the existing knowledge on the mechanical performance of TRM/TRC systems under elevated temperatures and fire conditions; and (ii) highlighting the most important issues of testing procedures and protocols. The paper refers to both TRM- and TRC-related data. The former include experimental assessments of the: (a) TRM-to-substrate residual bond characteristics as a function of temperature; and (b) structural performance of fired masonry elements furnished with a new type of TRM-based overlay for combined structural and energy upgrading. TRC-related data focus on the structural degradation of thin TRC plates under both standard and non-standard fire conditions.


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