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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: 

SP224-06

Date: 

December 1, 2004

Author(s):

Don Zakariasen and Vic Perry

Publication:

Symposium Papers

Volume:

224

Abstract:

Ductal® is a new material technology offering a unique combination of superior characteristics including ductility, strength, and durability, while providing highly moldable products with a quality surface. The technology provides compressive strengths up to 200 MPa (30,000 psi), and flexural strengths up to 50 MPa (7,200 psi). The material’s unique combination of superior properties enables the designer to create thinner sections, longer spans, and higher structures that are lighter, more graceful and innovative in geometry and form while providing superior durability and impermeability against corrosion, abrasion, and impact. This material provides the precast industry with opportunities to improve many existing products and manufacture new products that will compete with other materials such as stainless steel, cast iron, ceramics, and others. This paper presents properties of the material, design assumptions for project solutions and the manufacture, installation and assembly procedures for specific projects including roof panels, 5 sided-boxes and anchor plates. Many economies gained from this new technology are a result of engineering new solutions for old problems. By utilizing the unique combination of superior properties, designs can eliminate passive reinforcing steel and experience reduced global construction costs, form works, labour and maintenance. Additionally, this relates to benefits such as improved construction safety, speed of construction, extended usage life and others.

DOI:

10.14359/13409


Document: 

SP224-01

Date: 

December 1, 2004

Author(s):

Graham T Gilbert

Publication:

Symposium Papers

Volume:

224

Abstract:

Thin, fiber reinforced cementitious products offer a useful balance of properties such as strength, toughness, environmental durability, moisture resistance, dimensional stability, fire resistance, aesthetics and ease of handling and installation. For more than 30 years, AR glass fibers have been at the forefront in the development of new applications of such products throughout the World. Glass Fiber Reinforced Concrete [GFRC] is a thin, cement composite based on AR glass fibers with an excellent strength to weight ratio. Extensive early laboratory work produced a test method for determining long term strength. The validity of this work has been proven by the large number of buildings clad with GFRC, as well as a vast range of other GFRC products, used over a this 30 year period. This paper explains the fundamental principles behind GFRC and gives examples of some of its uses. These applications range from high quality, architectural wall panels and decorative elements through to modular buildings down to low cost channel sections and utility components. New developments and techniques will also be discussed.

DOI:

10.14359/13404


Document: 

SP224-13

Date: 

December 1, 2004

Author(s):

B. Mobasher

Publication:

Symposium Papers

Volume:

224

Abstract:

Techniques for modeling the mechanical response of thin section cement-based composites intended for structural based applications are presented using a micromechanical approach. A layer model is used and the property of each layer is specified based on the fiber and matrix constituents in addition to the orientation and the stacking sequence in each lamina. The overall axial and bending stiffness matrix is obtained using an incremental approach which updates the material parameters. The simulation is conducted by imposing an incremental strain distribution, and calculating the stresses. A stress based failure criterion is used for the three failure modes of initiation of cracking, ultimate strength of matrix, and ultimate strength of lamina. As the cracking saturates the specimen, it results in a gradual degradation of stiffness. A continuum damage model based on a scalar damage function is applied to account for the distributed cracking. The model predicts the response of unidirectional, cross ply and angle ply laminae under tensile loading in longitudinal and transverse directions. The load-deformation responses under tension and flexure are studied. It is shown that by proper selection of modeling approach, parameter measurement, and theoretical modeling, a wide range of analysis tools and design guidelines for structural applications of FRC materials are attainable.

DOI:

10.14359/13416


Document: 

SP224-12

Date: 

December 1, 2004

Author(s):

Luca Sorelli, Nemkumar Banthia and Giovanni A. Plizzari

Publication:

Symposium Papers

Volume:

224

Abstract:

Hybrid fiber reinforcement of cement composites is rapidly emerging as an innovative and promising way of improving mechanical performance and durability of cement-based materials. In the present paper, fracture behavior of medium, high and very high strength mortars reinforced with hybrid fibers was experimentally studied by using contoured double cantilever beam specimens. Different combinations of small steel fibers and fibrillated polypropylene micro-fibers are investigated. These composites are very suitable for thin sheet products such as roofing sheets, tiles, curtain walls, cladding panels, permanent forms, etc. Aim of the paper was to study the influence of matrix strength, fiber type and fiber combinations on the fracture toughness of the resulting fiber reinforced mortars. Results indicate that some combinations of fibers and matrix strengths exhibit a higher resistance to crack growth and evidence the contribution of polypropylene fibers to mortar toughness.

DOI:

10.14359/13415


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