International Concrete Abstracts Portal

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International Concrete Abstracts Portal

Showing 1-10 of 484 Abstracts search results

Document: 

SP-337_05

Date: 

January 23, 2020

Author(s):

Kjell Tore Fosså and Widianto

Publication:

Special Publication

Volume:

337

Abstract:

This paper describes the development in concrete technology for offshore concrete structures from the 1970’s until now and discusses some potential topics for future research which would result in more cost-effective offshore concrete structures.

Most of the offshore concrete structures constructed in the last 4 decades are still in operation, with no or only minor maintenance required, even though the average age for these structures in the North Sea is more than 25 years. The compressive strength in offshore structures has gradually increased from about 40MPa (5800 psi) in the 1970’s to more than 100MPa (14500 psi) in some of the latest concrete structures. Standards and concrete specifications have been revised several times during these years. In parallel, the knowledge from several research and development programs has been used to further improve the concrete properties and overcome the limitations. Focus has been primarily to improve the compressive strength of the concrete as well as the durability and concrete workability. The cement and admixture industry have been heavily involved in research programs to further adapt and develop these material properties. The result of the product developments in the concrete constituency has also improved cost-effectiveness and durability (including overall life-cycle cost-effectiveness) for offshore concrete structures.

With the new generation technology, the technical limitations we face today will be overcome. With more knowledge and improved technology, the quantity and size of cracks in concrete in service are expected to be reduced, which would also improve durability. In addition, the focus in the future will also be on sustainable and environmentally friendly materials.


Document: 

SP-336_07

Date: 

December 11, 2019

Author(s):

David Darwin, Rouzbeh Khajehdehi, Muzai Feng, James Lafikes, Eman Ibrahim, Matthew O’Reilly

Publication:

Special Publication

Volume:

336

Abstract:

The goal of this study was to implement cost-effective techniques for improving bridge deck service life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the creation of Low-Cracking High-Performance Concrete (LC-HPC) specifications that minimize cracking through the use of low slump, low paste content, moderate compressive strength, concrete temperature control, good consolidation, minimum finishing, and extended curing. This paper documents the performance of 17 decks constructed with LC-HPC specifications and 13 matching control bridge decks based on crack surveys. The LCHPC bridge decks exhibit less cracking than the matching control decks in the vast majority of cases. Only two LCHPC bridge decks have higher overall crack densities than their control decks, which are the two best performing control decks in the program, and the differences are small. The majority of the cracks are transverse and run parallel to the top layer of the deck reinforcement. The results of this study demonstrate the positive effects of reduced cement paste contents, concrete temperature control, limitations on or de-emphasis of maximum concrete compressive strength, limitations on maximum slump, the use of good consolidation, minimizing finishing operations, and application of curing shortly after finishing and for an extended time on minimizing cracking in bridge decks.


Document: 

CI4110Suprenant

Date: 

October 1, 2019

Author(s):

Bruce A. Suprenant

Publication:

Concrete International

Volume:

41

Issue:

10

Abstract:

A specification is a standard that establishes uniform criteria for a building product, assembly, technology, or project. Reference specifications can be important resources for code officials and specifiers creating contract documents. Citing an ACI reference specification in project specifications improves the quality of contract documents by providing an industry consensus standard that establishes uniform criteria for concrete construction.


Document: 

SP332

Date: 

August 8, 2019

Publication:

Special Publication

Volume:

332

Abstract:

The responsibilities for parties involved in a repair project may be significantly different than those traditionally encountered in new concrete construction. The new ACI 562 Code Requirements for Assessment, Repair and Rehabilitation of Concrete Buildings and corresponding ACI 563 Specifications for Repair of Concrete in Buildings identify requirements for the Licensed Design Professional and the contractor’s Specialty Engineer during repair programs. Differing lines of authority in repair are presented through industry practice recommendations and case studies, along with identification of industry needs, informing parties engaged in concrete evaluation and repair projects.


Document: 

SP-332_08

Date: 

July 1, 2019

Author(s):

Ashok Kakade

Publication:

Special Publication

Volume:

332

Abstract:

When preparing ready-mix concrete for private applications, it is typically recommended that owners and contractors collaborate with suppliers and concrete specialists to understand the possibilities and limitations of concrete in their applications. Here, we describe a situation in which a homeowner took direct control over the exact specifications of concrete and admixtures, and ultimately resulted in an unsatisfactory concrete slab. The owner subsequently sued and settled with the concrete supplier outside of the court, which raises important questions regarding who maintains responsibility for concrete mixtures, their installation, and the final slab results. Suggestions are provided to help mitigate this problem.


Document: 

CI4102Widianto

Date: 

February 1, 2019

Author(s):

Widianto, Erik Åldstedt, Kjell Tore Fosså, Jonathan Hurff, and Mohammad S. Khan

Publication:

Concrete International

Volume:

41

Issue:

2

Abstract:

A gravity-based structure (GBS) is a massive foundation placed on the seabed to serve as the base for offshore structures. The design, material specifications, and construction of GBS systems are covered by “Guide for the Design and Construction of Fixed Offshore Concrete Structures (ACI 357R).” A task group within ACI Committee 357, Offshore and Marine Concrete Structures, is currently updating the document.


Document: 

SP327

Date: 

November 20, 2018

Publication:

Special Publication

Volume:

327

Abstract:

Fiber-reinforced polymer (FRP) composite materials been widely used in civil engineering new construction and repair of structures due to their superior properties. FRP provides options and benefits not available using traditional materials. The promise of FRP materials lies in their high-strength, lightweight, noncorrosive, nonconducting, and nonmagnetic properties. ACI Committee 440 has published reports, guides, and specifications on the use of FRP materials for may reinforcement applications based on available test data, technical reports, and field applications. The aim of these document is to help practitioners implement FRP technology while providing testimony that design and construction with FRP materials systems is rapidly moving from emerging to mainstream technology.

This volume represents the thirteen in the symposium series and could not have been put together without the help, dedication, cooperation, and assistance of many volunteers and ACI staff members. First, we would like to thank the authors for meeting our various deadlines for submission, providing an opportunity for FRPRCS-13 to showcase the most current work possible at the symposium. Second, the International Scientific Steering Committee, consisting of many distinguished international researchers, including chairs of past FRPRCS symposia, many distinguished reviewers and members of the ACI Committee 440 who volunteered their time and carefully evaluated and thoroughly reviewed the technical papers, and whose input and advice have been a contributing factor to the success of this volume.


Document: 

SP327-45

Date: 

November 1, 2018

Author(s):

Alvaro Ruiz Emparanza, Raphael Kampmann and Francisco De Caso y Basalo

Publication:

Special Publication

Volume:

327

Abstract:

One of the main reasons for the degradation of our infrastructure is steel corrosion in reinforced concrete. To com- bat that issue, alternative non-corrosive materials, such as fiber reinforced polymer (FRP) rebars, were developed and implemented as internal reinforcement for concrete structures. Because of significant physio-mechanical advantages (magnetic transparency, high strength, corrosion resistance, etc.), the adoption of FRP rebars increased rapidly through- out the last decades. Due to an increased material demand, the number of FRP rebar manufacturers grew, but each manufacturer started to develop proprietary products, with wide ranging properties — the industry is in need for guidance and unification. Therefore, this study aims to centralize the relevant information by (i) summarizing the globally available regulations, (ii) providing background data for the present production status, and (iii) listing the currently produced FRP rebars in an effort to compare their physio-mechanical properties. Analysis of the market showed that 27 manufacturers produce FRP rebars in 14 countries with diverse output quantities and different distribution logistics. The various production approaches lead to different rebar types with dissimilar surface properties and significant strength differences.


Document: 

SP327-43

Date: 

November 1, 2018

Author(s):

Wassim M. Ghannoum, Nawaf K. Alotaibi, Jose Garcia, Chang Hyuk Kim, Yungon Kim, Douglas Pudleiner, Kevin Quinn, Neil Satrom, William Shekarchi, Wei Sun, Helen Wang, and James O. Jirsa

Publication:

Special Publication

Volume:

327

Abstract:

Strengthening using carbon fiber reinforced polymers (CFRP) provides a valuable addition to available structural preservation and life extension techniques. Damaged bridges can be repaired efficiently while structurally deficient bridges can be effectively retrofitted to higher load capacities using CFRP materials. A large research program has been ongoing since 2008 in Texas to demonstrate the effectiveness of using anchored CFRP sheets in shear strengthening of reinforced concrete bridge beams and girders. The research program has encompassed three main thrusts: 1) over 70 large-scale tests of concrete bridge sections strengthened using externally applied anchored CFRP sheets, 2) small-scale tests aimed at developing CFRP anchor design criteria as well as a simple test procedure for quality control of materials and installation, and 3) developing design specifications for CFRP anchors and sheets in shear strengthening applications. An overview of the experimental findings of the program is presented.


Document: 

SP327-14

Date: 

November 1, 2018

Author(s):

Paolo Rocchetti, Guillermo Claure, Francisco De Caso, and Antonio Nanni

Publication:

Special Publication

Volume:

327

Abstract:

The aim of this project is to develop the necessary design knowledge to implement GFRP reinforcement in concrete traffic barriers. Innovation lies in the use of GFRP closed continuous stirrups that became recently available. The design method relies on AASHTO-LRFD Bridge Design Specification and the latest development in specifications issued by the Florida Department of Transportation (FDOT) for Reinforced Concrete (RC) Traffic Barriers. After a review of design procedures for traffic barriers and understanding the mechanical characteristics of GFRP reinforcement, a modified design approach is proposed to reduce GFRP reinforcement amounts and complexity in construction. Supported on experience gained from designing FDOT 32” F–Shape (F32) GFRP RC used in the Halls River Bridge Replacement Project, this study also addressed the 36”–Single Slope (SS36) traffic barrier to be adopted by FDOT in coming years.


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