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International Concrete Abstracts Portal

Showing 1-5 of 35 Abstracts search results

Document: 

SP289

Date: 

October 1, 2012

Author(s):

Editors: Terence C. Holland, Pawan R. Gupta, V.M. Malhotra

Publication:

Symposium Papers

Volume:

289

Abstract:

This CD contains the proceedings from the Twelfth International Conference on Recent Advances in Concrete Technology and Sustainability Issues held in Prague, Czech Republic, in October 2012. The 34 papers include Advances in Geological CO2 Sequestration and Co-Sequestration with O2; Self-Compacting High-Performance Concretes; Dynamic Performance of Eco-Friendly Prestressed Concrete Sleeper; Parameters Influencing the Performance of Shrinkage-Compensating Concrete, and much more. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-289

DOI:

10.14359/51684136


Document: 

SP289-01

Date: 

September 14, 2012

Author(s):

Circe A. Verba, William K. O’Connor, and Jason H. Ideker

Publication:

Symposium Papers

Volume:

289

Abstract:

The injection of CO2 for Enhanced Oil Recovery (EOR) and sequestration in brine-bearing formations for long term storage has been in practice or under investigation in many locations globally. This study focused on the assessment of cement wellbore seal integrity in CO2- and CO2-O2-saturated brine and supercritical CO2 environments. Brine chemistries (NaCl, MgCl2, CaCl2) at various saline concentrations were investigated at a pressure of 28.9 MPa (4200 psi) at both 50oC and 85oC. These parameters were selected to simulate downhole conditions at several potential CO2 injection sites in the United States. Class H portland cement is not thermodynamically stable under these conditions and the formation of carbonic acid degrades the cement. Dissociation occurs and leaches cations, forming a CaCO3 buffered zone, amorphous silica, and other secondary minerals. Increased temperature affected the structure of C-S-H and the hydration of the cement leading to higher degradation rates.

DOI:

10.14359/51684250


Document: 

SP289-03

Date: 

September 14, 2012

Author(s):

Tae-Hoon Koh, Young-Hoon Bae, Seon-Keun Hwang, and Myung Sagong

Publication:

Symposium Papers

Volume:

289

Abstract:

In Korea, high-early-strength Portland cement has been used for railway PC (Prestressed Concrete) sleeper to provide high strength and rapid hardening satisfactorily at early period. However, it is fact that carbon dioxide (CO2) emission from the cement production has been recently one of the main social issues. In this study, eco-friendly PC sleeper, which was developed in order to reduce the usage of cement and natural resources (fine aggregate) as main ingredients of concrete, was tested using UTM (Universal Testing Machine) test facility in order to estimate its dynamic performance optionally required by the European Standard. Based on a series of dynamic performance tests, it was found that eco-friendly PC sleeper can be an environmental as well as mechanical alternative to the ordinary PC sleeper.

DOI:

10.14359/51684252


Document: 

SP289-02

Date: 

September 14, 2012

Author(s):

Mario Collepardi, Roberto Troli, and Stefano Maringoni

Publication:

Symposium Papers

Volume:

289

Abstract:

Self-compacting high-performance concretes have been manufactured by mixing natural aggregates, portland cement and ground limestone filler in the presence of a poly-carboxylate superplasticizer. In some concrete mixtures a shrinkage-reducing admixture (SRA) was used to decrease the drying shrinkage by 30% with respect to the control mix without SRA when the specimens were kept at room temperature with a relative humidity (RH) permanently kept as low as 55%. A special SCC was manufactured combining a CaO-based expansive agent with SRA and the restrained expansion was measured in the absence of any wet curing in very dry environment (RH = 50%). After 2-3 months the restrained expansion was lost but no crack was recorded although the RH was very low. Similar results were obtained by using a combination of PVA macrofibres with SRA: no reduction in drying shrinkage was recorded in the PVA-SRA concrete with respect to the SRA concrete. However, in the presence of PVA both the number and the thickness of the cracks were significantly reduced. The combined uses of SRA with the expansive agent or the macrofibres make more reliable concretes from the durability point of view because of the absence of cracks.

DOI:

10.14359/51684251


Document: 

SP289-05

Date: 

September 14, 2012

Author(s):

Aniello Palmieri, Stijn Matthys, and Luc Taerwe

Publication:

Symposium Papers

Volume:

289

Abstract:

The use of near surface mounted (NSM) fibers reinforced polymers (FRP) is being increasingly recognized as a valid technique for repairing and strengthening of concrete members. As this technology emerges, the structural behavior of NSM FRP strengthened elements needs to be characterized, and bond between NSM FRP bars and concrete is the first issue to be addressed. This paper presents the results of a series of 18 double shear tests on NSM FRP strengthened concrete. Aim of the project is to investigate the feasibility of the adopted test method and to investigate the mechanism of bond between NSM reinforcement and substrate material. Experimental results confirm the efficiency and reliability of the test method and the bond effectiveness of the NSM technique. Moreover, a local bond stress-slip relationship is determined based on experimental results and the outcome of a numerical investigation obtained from the DIANA TNO finite element analysis.

DOI:

10.14359/51684254


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