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International Concrete Abstracts Portal

Showing 1-5 of 17 Abstracts search results

Document: 

SP168-07

Date: 

April 1, 1997

Author(s):

Mary Sansalone, Jiunn-Ming Lin, and William B. Streett

Publication:

Symposium Papers

Volume:

168

Abstract:

This paper describes the use of a P-wave-speed measurement technique in conjunction with the impact-echo method to nondestructively and accurately determine the thickness of new concrete pavements and other plate-like structures. Portable instrumentation (computer, data-acquisition hardware, transducers, and impactors) that can be used to perform both wave speed and impact-echo measurements accurately and reliably is described. Results of preliminary field studies carried out on a Strategic Highway Research Program (SHRP) Test Section in Arizona are reported, including results obtained from pavements having different thicknesses, different strengths, and placed on different types of subgrades. The goal of this work 8 to lay the basis for an ASTM Standard Test Method for determining the thickness of concrete pavements and other plate-like structures.

DOI:

10.14359/5954


Document: 

SP168-16

Date: 

April 1, 1997

Author(s):

Allen G. Davis and Bernard H. Hertlein

Publication:

Symposium Papers

Volume:

168

Abstract:

Large concrete structures such as dams and bridge abutments and piers built over 50 years ago were usually constructed of mass concrete with no or little reinforcing steel. Most of these structures are in service today, and make up a considerable part of the infrastructure. Concern about their reliability and residual life now prompts owners to initiate structural inspections. The traditional approach of coring and visual inspection alone does not necessarily provide a full over for this evaluation. The more familiar nondestructive tests (NDT) such as rebound hammer, ultrasonic pulse velocity and similar surface tests are usually unsuccessfbl in providing information about bulk concrete quality at depth. This paper reviews two novel NDT methods that can address this problem: sonic ogging and parallel seismic, and presents three case histories that illustrate their application.

DOI:

10.14359/5947


Document: 

SP168

Date: 

April 1, 1997

Author(s):

Editors: Stephen Pessiki and Larry Olson / Sponsored by: ACI Committee 228

Publication:

Symposium Papers

Volume:

168

Abstract:

ACI Committee 228 has been active in the field experiences in the area of nondestructive testing of concrete. This volume contains 16 papers of which many were presented at the two most recent technical sessions organized by the committee. The first session was held during the ACI Spring Convention in 1993 in Vancouver, BC, Canada. The second session was held during the American Concrete Institute Fall Convention in 1995 in Montreal, Quebec, Canada. 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. SP168

DOI:

10.14359/14208


Document: 

SP168-14

Date: 

April 1, 1997

Author(s):

Xuli Fu and Il. Il. L. Chung

Publication:

Symposium Papers

Volume:

168

Abstract:

The contact electrical resistivity was found to correlate with the shear bond strength between steel rebar and concrete, between stainless steel fiber and cement paste, and between carbon fiber and cement paste. For the bond between steel rebar and concrete and that between stainless steel fiber (untreated or acetone washed) and cement paste, the contact resistivity increased linearly with increasing bond strength, due to an interfacial phase of high volume resistivity that helped the bonding. For the bond between stainless steel fiber (acid washed) and cement paste and that between carbon fiber (untreated) and cement paste, the contact resistivity decreased with increasing bond strength, due to the bond degradation by interfacial voids, which were high in volume resistivity. The acid washing of the stainless steel fiber decreased the contact resistivity, but had little effect on the bond strength. The high volume resistivity interfacial phase that enhanced the bonding between the untreated or acetone washed stainless steel fiber and cement paste apparently required for its formation the oxide layer on the stainless steel surface. The removal of the oxide layer by acid washing eliminated this phase, thus decreasing the contact resistivity and causing the contact resistivity to decrease with increasing bond strength. For a given interface at a given curing age, the correlation between bond strength and contact resistivity allows the bond strength to be nondestructively measured via contact resistivity measurement.

DOI:

10.14359/5945


Document: 

SP168-09

Date: 

April 1, 1997

Author(s):

Randall Poston and Mary Sansalone

Publication:

Symposium Papers

Volume:

168

Abstract:

This paper presents both a brief explanation of the impact response of bar-like structures and an application involving the use of the impact-echo method for detecting cracks in the beams and columns of a post-tensioned parking garage structure. The information gained from the impact-echo tests was used to aid in specifying repair measures for the structure. In the process of implementing repair measures, selected impact-echo results were verified. This field study was performed in 1991. This paper was presented at the AC1 Fall Convention in 1992.

DOI:

10.14359/5956


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