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International Concrete Abstracts Portal

Showing 1-5 of 980 Abstracts search results

Document: 

SP-349_18

Date: 

April 22, 2021

Author(s):

Ivan Janotka, Michal Bačuvčík, Peter Paulík, and Lukáš Húlek

Publication:

Symposium Papers

Volume:

349

Abstract:

A layer of 2-4 mm (0.08-0.16 in) protective render coat (PRC) has proven to be an effective anticarbonation barrier at two bridges protecting the underlying concrete against carbonation for 100 years. The carbonation of concrete under the PRC with low permeability was found to be less than 2 mm (0.08 in). It is assumed that the PRC was placed for aesthetic purposes. Taking into account the considered XC3 exposure class according to EN 206, to which concrete structures were subjected and compressive strengths of the underlying concrete between 20 - 25 MPa (2900 - 3625 psi), low carbonation depth can be explained by the presence of the PRC applied on concrete surface. The main scientific goal of this article is to explain the cause of extremely low carbonation depth of concrete under the PRC. Its composition has been unknown until now but the present research reveals the secret of this substance. Investigations of the aspects of low carbonation depth thoroughly focused on the PRC role covering concrete beneath as well as material development of new current PRC based on the present cement and sand, without the use of chemical admixtures, are also the subject of ongoing research.


Document: 

SP346

Date: 

March 9, 2021

Author(s):

Sponsored by ACI Committee 345

Publication:

Symposium Papers

Volume:

346

Abstract:

A Sustainable built-environment requires a comprehensive process from material selection through to reliable management. Although traditional materials and methods still dominate the design and construction of our civil infrastructure, nonconventional reinforcing and strengthening methods for concrete bridges and structures can address the functional and economic challenges facing modern society. The use of advanced materials, such as fiber reinforced polymer (FRP) and ultra-high performance concrete (UHPC), alleviates the unfavorable aspects of every-day practices, offers many new opportunities, and promotes strategies that will be cost-effective, durable, and readily maintainable. Field demonstration is imperative to validate the innovative concepts and findings of laboratory research. Furthermore, documented case studies add value to the evaluation of emerging and maturing technologies, identify successful applications or aspects needing refinement, and ultimately inspire future endeavors. This Special Publication (SP) contains nine papers selected from three technical sessions held during the virtual ACI Fall Convention of October 2020. The first and second series of papers discuss retrofit and strengthening of super- and substructure members with a variety of techniques; and the remaining papers address new construction of bridges with internal FRP reinforcing and prestressing in beam, slabs, decks and retaining walls. All manuscripts were reviewed by at least two experts in accordance with the ACI publication policy. The Editors wish to thank all contributing authors and anonymous reviewers for their rigorous efforts. The Editors also gratefully acknowledge Ms. Barbara Coleman at ACI for her knowledgeable guidance.


Document: 

SP-345_01

Date: 

February 1, 2021

Author(s):

Arne Spelter, Juliane Wagner, Manfred Curbach, and Josef Hegger

Publication:

Symposium Papers

Volume:

345

Abstract:

Carbon reinforced concrete (CRC) is a material composed of a high-performance concrete and a carbon reinforcement (textile grids, lamellas, rods). Composite materials with reinforcements of other fiber materials are called textile reinforced concrete (TRC). The investigations of CRC started more than 20 years ago and the continuous development as well as research findings have opened many fields of application. Today, the use of CRC includes the strengthening of reinforced concrete elements as well as the realization of new elements such as facades, shells and even bridges.

Some of these structures require knowledge of the fatigue behavior due to cyclic loading (e. g. bridges). In a collaborative project of the Institute of Structural Concrete of the RWTH Aachen University and the Institute of Concrete Structures of the TU Dresden, the uniaxial tensile fatigue behavior of two carbon textile reinforcement types was systematically investigated. The specimens were subjected up to 107 loading cycles and stress ranges up to 261 ksi (1,800 MPa). The influence of the maximum load and amplitude were investigated as well as fatigue curves for these two reinforcement types derived.


Document: 

SP-345_02

Date: 

February 1, 2021

Author(s):

Jan Bielak, Norbert Will, Josef Hegger, and Sven Bosbach

Publication:

Symposium Papers

Volume:

345

Abstract:

Textile-reinforced concrete (TRC) combines high-performance fabrics made of impregnated carbon yarns with state-of-the-art high strength concrete. Due to the corrosion resistance of non-metallic reinforcement, the application of TRC for external components especially with freeze-thaw and de-icing salt exposure is promising. This allows for reduction of concrete cover, to create slender structural elements and to execute thin slabs without additional waterproofing or protective decking. Different existing theoretical models and experience from various research projects were used in design of several pedestrian- and road bridges in Germany. The pedestrian bridges in Rems Valley and Ottenhöfen use TRC slabs without shear reinforcement as transversal loadbearing component. For the road bridges in Gaggenau, skew slabs made of TRC with shear reinforcement were chosen as principal structural system. Prior and during construction, experimental investigations on shear capacity were performed at the Institute of Structural Concrete (IMB) of RWTH Aachen. A comprehensive characterization of the material properties of the non-metallic reinforcement is a prerequisite for transfer and adaption of existing design rules, e.g. the determination of tensile strength of the bent portion of pre-formed shear reinforcement. This paper highlights the application potential and further challenges for the use of textilereinforced concrete in new engineering constructions.


Document: 

SP-346_05

Date: 

January 1, 2021

Author(s):

Mohit Soni

Publication:

Symposium Papers

Volume:

346

Abstract:

Alternative reinforcement such as Glass Fiber Reinforced Polymer (GFRP) and Basalt (BFRP) are gaining popularity due to their corrosion resistant properties in extremely aggressive environments. The Florida Department of Transportation was concerned with the long-term durability of fiber resin systems in wet marine environments and restricted its use in submerged marine locations. This paper demonstrates the implementation of a pilot project after the thorough evaluation of a Fiber Reinforced Polymer resin prior to broader deployment of the alternative reinforcement. The paper focuses on the successful construction implementation to provide an archival reference document for future study and comparison to look at the long-term performance and integrity of the strengthening systems. During the execution of this pilot project, several lessons were learned and are demonstrated in this paper.


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