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Showing 1-5 of 26 Abstracts search results

Document: 

SP189

Date: 

January 1, 2000

Author(s):

Editor: H.G. Russell

Publication:

Symposium Papers

Volume:

189

Abstract:

A total of 25 papers are included in this Symposium Publication on HPC. The general topics include HPC bridges, HPC structural lightweight concrete, material science of HPC, and structural safety of HPC. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP189

DOI:

10.14359/14224


Document: 

SP189-18

Date: 

January 1, 2000

Author(s):

K. Kovler, I. Schamban, S.-I. Igarashi and A. Bentur

Publication:

Symposium Papers

Volume:

189

Abstract:

Statistical relationships between compressive strength, tensile splitting strength and autogenous shrinkage of early-age high-performance concrete (HPC), on one hand, and water/binder ratio, silica fume (SF) incorporated in the mix and concrete age, on the other hand, are drawn. The methods of experimental design are used. It is shown that the tensile and compressive strength obtained is higher for higher SF content. However, the ratio of tensile to compressive strength decreased with increase in SF. These trends triggered the authors to study the complex behavior of early-age HPC, including the phenomenon of autogenous shrinkage and the cracking damage that it may induce. Convenient nomograms for use by practicing engineers for the prediction of both strength and shrinkage properties, were developed.

DOI:

10.14359/5859


Document: 

SP189-12

Date: 

January 1, 2000

Author(s):

J. S. Lawler, D. T. Keane, and S. P. Shah

Publication:

Symposium Papers

Volume:

189

Abstract:

The fracture process of cement-based material cause by compressive loading is a complex, three-dimensional phenomenon that occurs as a result of material heterogeneity and complicated mixed-mode cracking mechanisms. However, obtaining three-dimensional information describing this process requires equipment-and time-intensive techniques. One such technique is X-ray Microtomography, which provides high resolution data, but is limited to small specimens. A more straightforward technique, Digital Image Correlation (DIC), can be used to characterize the fracture pattern of a wider range of specimens, but only in two dimensions on the surface. In order to determine the relationship between surface and internal cracking mortar specimens were tested in compression and examined using both DIC and X-ray Microtomography. Microtomography is an X-ray technique that can be used to produce three-dimensional images which reveal the full internal structure of the specimen, including cracks and pores. DIC is a Computer Vision technique that compares successive images to measure two-dimensional deformation on the surface of the specimen, providing information on the location and opening of surface cracks. Rectangular mortar specimens (25.4 mm by 12.7 mm by 12.7 mm) were loaded to certain levels past the peak stress to induce significant cracking and then unloaded. Deformations of the unloaded specimen were measured with DIC and used to determine crack shape, size and location. This surface phenomena was compared to the shape and size of internal cracks seen in tomographic reconstructions of the same specimen. It was observed that these techniques give complementary information about crack geometry and development.

DOI:

10.14359/5853


Document: 

SP189-08

Date: 

January 1, 2000

Author(s):

J. F. Speck and R. G Burg

Publication:

Symposium Papers

Volume:

189

Abstract:

This paper presents three examples of low density, all lightweight aggregate concrete applications. These applications represent "high performance" concrete because the concrete properties could no be achieved with the usual materials and methods. Each example used rotary kiln produced expanded clay lightweight aggregates to obtain concrete densities as low as 75 lb/ft3. Where required, relatively high strength concrete (6000 psi) was produced. In another instance, the compressive strength was purposely limited to less than 3000 psi. In each case the concrete met the needs of the user, resulting in significant cost savings.

DOI:

10.14359/5849


Document: 

SP189-01

Date: 

January 1, 2000

Author(s):

M. W. Beacham

Publication:

Symposium Papers

Volume:

189

Abstract:

The AASHTO “Task Force on Strategic Highway Research Program (SHRP) Implementation” developed and instituted the Lead State Program in 1996. The mission of the Task Force was to optimize ways in which SHRP technologies could be implemented at the state level. The Task Force understood the benefits of mutual cooperation in sharing resources, working as teams, and collectively implementing the technologies. In order to achieve their mission the Task Force developed the concept of “Lead States Teams”. A “Lead States Team” is a group of states that are willing to take the lead and assist in the implementation of specific, targeted SHRP technologies in which they have interest and have gained some practical experience.

DOI:

10.14359/5842


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