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International Concrete Abstracts Portal

Showing 1-5 of 5 Abstracts search results

Document: 

103-M01

Date: 

January 1, 2006

Author(s):

Jeffery R. Roesler, Salah A. Altoubat, David A. Lange, Klaus-Alexander Rieder, and Gregory R. Ulreich

Publication:

Materials Journal

Volume:

103

Issue:

1

Abstract:

Large-scale load testing was completed on both plain and fiberreinforced concrete slabs-on-ground. The fiber-reinforced concrete used a new synthetic macrofiber. Although the synthetic fibers did not alter the tensile cracking load of the plain concrete slab, the flexural cracking load of the plain concrete slab was increased by 25 and 32% with synthetic fiber addition of 0.32 and 0.48% by volume, respectively, for the center loading configuration. Similarly, synthetic fibers at 0.48% volume fraction increased the flexural cracking load of plain concrete slab under edge loading by 28%. The ultimate load capacity of the plain concrete slab under center loading was increased by 20 and 34% with the addition of 0.32 and 0.48% synthetic fibers, respectively. Embedded strain gauges in the concrete slabs and deflection profile measurements indicated the fibers effectively distributed the load throughout the slab volume as cracking progressed, resulting in the increased concrete slab flexural and ultimate capacities.

DOI:

10.14359/15121


Document: 

101-M08

Date: 

January 1, 2004

Author(s):

Christopher Y. Tuan

Publication:

Materials Journal

Volume:

101

Issue:

1

Abstract:

Conductive concrete is a category of concrete containing electrically conductive components to attain stable and high electrical conductivity. Due to its electrical resistance and impedance, a thin conductive concrete overlay can generate enough heat to prevent ice formation on a bridge deck when connected to a power source. Steel fibers and steel shavings were used for the conductive materials in this study. A conventional concrete slab, 1.2 x 3.6 m (4 x 12 ft), has been constructed with a 9 cm (3.5 in.) conductive concrete overlay for conducting deicing experiments in the natural environment. The conductive concrete mixture was developed at the University of Nebraska-Lincoln specifically for bridge deck deicing. Anti-icing and deicing experiments were conducted in five snowstorms. The average power density of approximately 590 W/m2 (55 W/ft2) was delivered to the conductive concrete overlay to prevent snow accumulation and ice formation. The experiment setup, energy consumption, and costs during the winter storms of 1998 are presented. A coupled thermal-electric finite element analysis was conducted to study the joule heating of the conductive concrete overlay. The numerical results showed that the model served as a useful tool for predicting the heating performance of the conductive concrete overlay.

DOI:

10.14359/12989


Document: 

99-M44

Date: 

September 1, 2002

Author(s):

Arvind K. Suryavanshi, R. Narayan Swamy, and George E. Cardew

Publication:

Materials Journal

Volume:

99

Issue:

5

Abstract:

The objective of the present study is to identify a simple, reliable, and rational method for evaluating chloride ion diffusion coefficients for civil engineering applications. To make the conclusions of the study relevant to field concrete structures, the chloride penetration data used to estimate the diffusion coefficients were generated using fairly large-sized reinforced concrete slabs subjected to long-term cyclic exposure to a chloride environment. Furthermore, to make the study comprehensive, the parameters influencing the microstructure of the concrete such as water-to-binder ratio (w/b) and supplementary mineral admixtures were included. The simplified linear error-function-based method (SLEM) and Newton-Raphson method estimated almost identical values of diffusion coefficients irrespective of the w/b and the type of mineral admixture in the mixture, while the least square fit method estimated consistently lower diffusion coefficients. On the other hand, the values of diffusion coefficients estimated by the graphical method showed a mixed trend of higher and lower values compared with those estimated by the other three methods. Nevertheless, all four methods employed to evaluate the chloride ion diffusion were unanimous in estimating lower diffusion coefficients for the concrete slabs having mineral admixtures compared to the control concrete slab, and the slab cast with concrete of w/ b = 0.45.

DOI:

10.14359/12322


Document: 

96-M83

Date: 

November 1, 1999

Author(s):

Peter Marti, Thomas Pfyl, Viktor Sigrist, and Tomaz Ulaga

Publication:

Materials Journal

Volume:

96

Issue:

6

Abstract:

A circular slab test method is described as an alternative to modulus of rupture and square slab tests for steel fiber-reinforced concrete. Results of 20 modulus of rupture, 12 square slab, and 24 circular slab tests are compared based on a general theoretical approach that accounts for the random fiber distribution and the successive softening by fiber pullout. Existing requirements for modulus of rupture and square slab tests are reviewed, and harmonized procedures for these as well as the circular slab tests are proposed. It is suggested to use an effective flexural tensile strength and a fracture energy parameter to characterize the strength and toughness of steel fiber-reinforced concrete. Furthermore, an acceptance criterion is introduced, aiming at excluding materials with a too drastic softening.

DOI:

10.14359/794


Document: 

95-M32

Date: 

July 1, 1998

Author(s):

Nader Ghafoori and Zhiwang Zhang

Publication:

Materials Journal

Volume:

95

Issue:

4

Abstract:

The failure load is several times greater than the wheel loads of heavy trucks and, thus, it is accepted that the ultimate load-carrying capacity of bridge decks are safe enough to resist wheel loads in service state. However, many bridge decks in Korea have failed locally due to repeated and moving traffic loading. Therefore, the bridge decks, in regards to the fatigue problem, should be designed to ensure adequate safety and durability during design life. Previous researchers who investigated the fatigue behavior of bridge decks were concerned mainly with the following topics: reinforcement ratio; reinforcing methods (orthotropic and isotropic); and loading methods (fixed pulsating loads, stepwise moving pulsating loads, and simulated moving wheel-load). These tests were conducted at the center or centerline of the bridge deck panels, which were bounded by girders and diaphragms, and, thus, the effects of the loading positions were not considered. For this reason, the fatigue life of a bridge deck is usually expressed as a function of the punching shear strength at the center of the deck panel. If the center of the deck panel is not a critical point for fatigue loading, additional fatigue tests would be needed to investigate the position of the bridge deck, which is more critical for fatigue loading than the center of the panel. This paper is aimed at investigating the variations in punching shear strength and fatigue strength of composite bridge decks at various positions. Test results are compared with previous test results, especially results obtained by Hewitt. The experimental tests were conducted on one-third-scale model deck slabs, which were modeled to simulate a typical composite bridge deck. Punching tests were conducted at six positions, and three pulsating test positions were selected among the punching test positions. These loading positions were carefully selected based on the relative magnitude of the sectional forces (compressive in-plane forces and shear forces) in the slab, which were obtained by three-dimensional finite element analysis.

DOI:

10.14359/377


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