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International Concrete Abstracts Portal

Showing 1-5 of 12 Abstracts search results

Document: 

SP185-08

Date: 

February 1, 2000

Author(s):

P. H. Emmons and A. M. Vaysburd

Publication:

Symposium Papers

Volume:

185

Abstract:

A large variety of materials and techniques are available to increase strength of existing concrete structures in an effort to extend their service life. The way to make repaired and strengthened concrete structures durable is to ensure that the new composite system is "tailored" to serve the intended service life, and that the composite human system, the team involved with a project, is knowledgeable and experienced enough to recognize the complexity of their task. The paper reviewed traditional methods and also offers a review on the use of advanced composite materials for strenghening existing comcrete structures. The advantages and limitations of different techniques are presented. It is concluded that, in the futrue, advanced composite materials will be widely used for repair and strengthening. To achieve this, it is vital that research and engineering education in cement-based and advanced composite materials are improved.

DOI:

10.14359/5714


Document: 

SP185

Date: 

February 1, 2000

Author(s):

Editors: Neven Krstulovic-Opara and Ziad Bayasi

Publication:

Symposium Papers

Volume:

185

Abstract:

SP-185 Up until now there has been very little information on the use of high-performance fiber-reinforced concrete (HPFRC). But recent laboratory studies and field applications show that HPFRC improves performance of civil engineering infrastructure in a cost-effective manner. This publication includes 11 papers on the mechanical properties of HPFRC for infrastructural repair and retrofit.

DOI:

10.14359/14226


Document: 

SP185-05

Date: 

February 1, 2000

Author(s):

N. Banthia and C. Yan

Publication:

Symposium Papers

Volume:

185

Abstract:

In most industrialized countries of the world, bulk of the future activity in the construction sector will be related to repair and rehabilitation of the existing structures. Given the general inadequacy of our present repair materials, much future research is needed towards developing high performance repair materials especially for executing durable thin repairs and patching. In this paper, polymer modified micro-fiber reinforced concrete composites are evaluated as repair materials by conducting CMOD controlled repair bond tests in uniaxial tension. A significant improvement in the bond strength and bond fracture energy due to both fiber reinforcement and polymer modification is noted. In addition, surface preparation emerges as one of the most important variables controlling the strength and fracture energy of the bond.

DOI:

10.14359/5711


Document: 

SP185-10

Date: 

February 1, 2000

Author(s):

G. C. Brunnhoeffer, M. B. Farrell, N. M. Hawkins, W. L. Gamble, and F. P. Shkurti

Publication:

Symposium Papers

Volume:

185

Abstract:

Three reinforced concrete columns with inadequate strength, non-contact, lap splices at their base were tested to failure under reversed cyclic loading. An investigation was then made a method for jacketing such damaged columns in order to reinstate and improve their seismic performance. The damaged columns were jacketed using a steel fiber mat infiltrated with slurry and then again tested to failure under reversed cyclic loading. The degree of restoration and improvement in the seismic performance of the columns was partially dependent on the degree of damage suffered by the column during the initial non-jacketed testing. However, in all cases the jacketed columns exhibited load-deflection hysteretic characteristics equal to, and ductility characteristics exceeding, those of the non-jacketed column. Details are provided of the seismic performance characteristics of the columns, and the repair techniques used.

DOI:

10.14359/5716


Document: 

SP185-02

Date: 

February 1, 2000

Author(s):

Y. Shao, R. Srinivasan, and S. P. Shah

Publication:

Symposium Papers

Volume:

185

Abstract:

High performance fiber reinforced cement composites (HPFRC) are defined as the materials which exhibit a postpeak strain hardening type of response with a multiple crack pattern. Such a ductile behavior makes the HPFRC an ideal material to be used in structural repair and retrofit for dimensional stability, tensile-load carrying capacity, impact resistance, flexibility and long term impermeability. The critical parameter for continuous fiber reinforced cementitious materials to obtain the high performance response is the minimum fiber volume ratio with well dispersed fibers. As long as continuous fiber composites have a sufficient number of fibers to bridge the cracks, strain hardening and multiple cracking can always happen. However, there is no single dominant parameter which can control the multiple cracking process in discontinuous fiber composites. Various parameters can affect the postpeak response of discontinuous fiber reinforced cementitious materials. They are related to fibers, matrix and the processing methods. Parameters relating to the reinforcement include the type of fiber, fiber length, fiber volume ratio, fiber orientation, state of fiber dispersion and the degree of adhesion to the matrix. These primary variables are in turn influenced by selection of the matrix type, presence of additives, and the processing conditions. The latter acts through controlling the state of dispersion, establishing a fiber design a high performance fiber reinforced cementitious repair material, the approach in which the repair will be carried out should be considered simultaneously.

DOI:

10.14359/5708


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