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International Concrete Abstracts Portal

Showing 1-5 of 15 Abstracts search results

Document: 

SP224-02

Date: 

December 1, 2004

Author(s):

Gregor Vilkner and Christian Meyer

Publication:

Symposium Papers

Volume:

224

Abstract:

Thin sheet concrete products are receiving increased attention because of the large number of potential applications. By using crushed glass as aggregate, a multitude of different esthetic effects can be produced, which again open up numerous architectural and decorative uses. Such thin sheets are most effectively reinforced with fiber mesh, whether made of polypropylene, AR-glass, or other types of materials. At Columbia University, a project is currently under way to explore the possibilities of prestressing thin sheet glass concrete products. There are numerous performance criteria that need to be satisfied by the fiber mesh material in order to qualify for the tasks on hand. Most promising to date are high-performance materials such as aramid and carbon fiber mesh. This paper discusses the elimination process by which the most appropriate type of fiber mesh was selected. Various technical problems of prestressing and anchoring the fiber mesh are pointed out, as well as other issues that need to be resolved, before such products can be mass-produced commercially.

DOI:

10.14359/13405


Document: 

SP224-08

Date: 

December 1, 2004

Author(s):

Yixin Shao, Emmanuel Blain-Cosgrove and Brad Robinson

Publication:

Symposium Papers

Volume:

224

Abstract:

The balance between sustainability and affordability is hard to achieve when considering choices of building envelopes. A simple and easy-to-construct stressed skin structural sandwich system that is both affordable and sustainable is evaluated in this paper. The system is composed of an expanded polystyrene (EPS) panel core, wrapped in polymer mesh and covered with a thin cement skin on both sides. This system design leads to a highly energy efficient building envelope system. A full-scale sandwich wall was constructed and tested to examine the possibility of its use as a load bearing wall in one story residential house without traditional timber frames. Based on the requirements imposed by the National Building Code (NBC), the test results from this experimental program were found to be promising. The wall carried a gravity load, a wind load and seismic in-plane shear load at least 4 times as high as the NBC design load with negligible lateral displacement and no visible cracking. At buckling failure, the load-carrying capacity of the wall exceeded 10 times the design load. The EPS-core stressed-cement skin sandwich building system thus provides a good example of the use of thin cementitious products in load bearing exterior wall structural applications.

DOI:

10.14359/13411


Document: 

SP224-11

Date: 

December 1, 2004

Author(s):

Katherine G. Kuder and Professor Surendra P. Shah

Publication:

Symposium Papers

Volume:

224

Abstract:

Fiber-reinforced cement board (FRCB) is increasing in consumer popularity because it is more durable than conventional wood products. However, concerns exist about the freeze-thaw durability of the material due to its laminated structure and high porosity. To overcome these weaknesses, some manufacturers have begun to press the material after it is formed. The objective of this work is to evaluate the effects of this new processing on the durability of the FRCB. Three commercially-available FRCB products – two that had been pressed and one that had not – were subjected to accelerated freeze-thaw cycling according to a modified version of ASTM Standard C1185. The flexural strength, interlaminar bond (ILB) strength and porosity were measured. The results indicate that pressure might improve the ILB and flexural strength of the FRCB after freeze-thaw testing. However, porosity is not affected by pressure after freeze-thaw.

DOI:

10.14359/13414


Document: 

SP224-04

Date: 

December 1, 2004

Author(s):

Wolfgang Brameshuber, Matthias Koster, Josef Hegger, Stefan Voss, Thomas Gries, Marijan Barle, Hans-Wolf Reinhardt, and Markus Kruger

Publication:

Symposium Papers

Volume:

224

Abstract:

This paper presents engineering use of textile reinforced concrete (TRC) for integrated formwork applications. The integrated formwork are very light compared to the normal precast elemets owing to their small thickness, typically around 10 mm. The cross-section of the integrated formwork can be chosen as dictated by the specific application, and the composite can be designed to have a high load-bearing capacity. The young concrete is protected against moisture loss by the integrated formwork that remains in place. Hence, neither demoulding nor curing of TRC integrated formork is required. The integrated formwork also possess a high quality surface appearance. In this contribution, a compilation of results from testing performed on the textile reinforced concrete integrated formwork is presented.

DOI:

10.14359/13407


Document: 

SP224-14

Date: 

December 1, 2004

Author(s):

Momahed Boulfiza and Nemkumar Banthia

Publication:

Symposium Papers

Volume:

224

Abstract:

Cement-based composites, reinforced with randomly distributed short fibers exhibit a nonlinear behavior, called damage, which could be described in terms of microcrack initiation, growth and coalescence leading to the creation of macrocracks. A micromechanics-based continuum damage mechanics, MBCDM, model is proposed for the prediction of the effect of initial microcrack configuration and propagation on the macroscopic Young’s modulus and thermodynamic force associated with the chosen damage variable. Parametric studies for a number of periodic crack distributions in a two-dimensional case have been carried out. Both unreinforced (brittle) and pitch-based carbon fiber reinforced thin sheet cementitious materials have been considered. It is shown that despite the relative simplicity of the damage measure used, the model was able to capture the main effects of cracking patterns on the overall behavior of the composite. Simulation results also reveal that, whereas the evolution of the normalized stiffness is practically the same for all configurations over the entire range of damage variation, the damage thermodynamic force is different for each case. The results predicted by the proposed approach, appear to be consistent with experimental observations regarding the tensile behavior of CFRC composites.

DOI:

10.14359/13417


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