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International Concrete Abstracts Portal

Showing 1-5 of 6 Abstracts search results

Document: 

19-404

Date: 

September 1, 2020

Author(s):

Chaomei Meng, Liangcai Cai, Guanhu Wang, Xingang Shi, and Jianming Ling

Publication:

Materials Journal

Volume:

117

Issue:

5

Abstract:

Cross-tensioned prestressed concrete pavement (CTPCP) has superior mechanical and durable performance over ordinary concrete pavement. An approximate model to predict stresses and displacement of CTPCP under temperature loading is developed. Elasticplastic model is adopted to describe the performance of sliding layer between CTPCP and subgrade. The stresses in concrete are divided into friction introduced, curling, and prestressed components. Friction introduced component is obtained with the equivalent equation of CTPCP and curling component is obtained with Westergaard solution for concrete pavement with infinite length but finite width. Furthermore, influences of parameters, including length and thickness of slab, elastic modulus of concrete, frictional coefficient, space, angle and position of prestressed strands and reaction modulus of subgrade, on stresses and displacements are discussed. Results show that decreasing length and thickness of pavement, frictional coefficient, and elastic modulus of concrete are effective ways to reduce stress under temperature loading. Furthermore, decreasing space but increasing diameter of prestressed strands is another way to prevent too large tensile stress in CTPCP. Additionally, it seems to be more concise that the perfect plastic model is adopted to predict friction introduced stress in engineering application after comparative analysis of difference between to bilinear model and plastic model.

DOI:

10.14359/51725979


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


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