International Concrete Abstracts Portal

International Concrete Abstracts Portal

The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

Showing 1-5 of 71 Abstracts search results

Document: 

SP126-67

Date: 

August 1, 1991

Author(s):

F. Massazza and G. Oberti

Publication:

Symposium Papers

Volume:

126

Abstract:

Compared to portland cements, pozzolanic cements can better resist various aggressive agents, such as pre and acidic waters, chlorides, and sulfates. Furthermore, they can also prevent expansion caused by alkali-aggregate reactions. Provided that concretes of the same strength are compared, the carbonation depth of pozzolanic cements is similar to that of portland cements. In Italy, where they have extensively been used for the construction of buildings and civil engineering works, pozzolanic cements accounted for over 15,000,000 t of cement production in 1989. This is, however, indirect evidence of the durability associated with this type of cement. Direct evidence is actually provided by many Italian dams built over 40 years ago, which, despite the heavy and manifold environmental conditions that they have been subjected to yearly, still show good serviceability.

DOI:

10.14359/3641


Document: 

SP126-36

Date: 

August 1, 1991

Author(s):

Gerardo G. Clemena and Donald R. Jackson

Publication:

Symposium Papers

Volume:

126

Abstract:

There is a need for a new anode for use in the impressed-current cathodic protection (CP) of inland concrete piers, which are deteriorating because of salt-induced corrosion of reinforcing bars. A new water-based conductive coating was used recently on the cathodic protection of some concrete piers in Virginia. Further, as a possible means of eliminating the need for regular site visits to inspect and insure that the CP is functioning properly (which is a disadvantage common to existing CP systems), a microprocessor-based data acquisition device that facilitates remote monitoring was tested with the system. This paper describes the design, installation, and performance of the CP system during its first year of operation.

DOI:

10.14359/3803


Document: 

SP126-47

Date: 

August 1, 1991

Author(s):

Steven Gebler

Publication:

Symposium Papers

Volume:

126

Abstract:

Addresses shotcrete used primarily for rehabilitating concrete structures. Field experience has demonstrated that the use of detailed specifications and strict on-site surveillance can minimize workmanship problems that have been a concern with the shotcrete process. This paper discusses key points that make the specifications a useful tool. Types of shotcrete quality found in practice are illustrated. Preconstruction testing, ongoing quality control testing during construction, a core grading system, and tensile bond strength tests are discussed. Several brief case histories are presented where the use of the core grading system has proved successful. In the case histories, an independent laboratory conducted evaluations of in-place shotcrete, developed specifications for new work, and provided on-site surveillance during placement. The case histories include a drydock, cooling tower, parking garage, swimming pool, lighthouse, and two chimneys. The system adopted has resulted in structures that should provide durable, long-term service.

DOI:

10.14359/3807


Document: 

SP126-60

Date: 

August 1, 1991

Author(s):

V. F. Stepanova

Publication:

Symposium Papers

Volume:

126

Abstract:

Presents the results of an investigation into the corrosion of steel in lightweight concretes made with different types of lightweight aggregates. After many years of investigation of reinforced concrete made with lightweight aggregates, it was revealed that they can have satisfactory resistance to salt attack. Previously, it was believed that the greater permeability of some lightweight aggregates would not permit their use in reinforced lightweight concrete structures on an equal basis with normal weight concrete. The investigation performed on the corrosion of steel in concretes of different compositions, employing accelerated test methods as well as industrial experience, indicates that it is possible to use lightweight concrete for load-bearing and enclosure structures in urban and civil engineering applications.

DOI:

10.14359/3811


Document: 

SP126-62

Date: 

August 1, 1991

Author(s):

C. L. Hwang, R. Y. Lin, J. C. Chen, and J. H. Kuo

Publication:

Symposium Papers

Volume:

126

Abstract:

The phenomenon of steel corrosion and concrete crack patterns under different water-to-cement ratios and cover depths of concrete was investigated. The steel corrosion of single reinforced concrete beam with different admixtures under repeated loading was also studied. It is possible to predict the crack patterns and mechanical behavior of concrete when steel corrosion is induced. The addition of inhibitors reduced the corrosion rate. If concrete undergoes repeated loadings, the resulting cracks will allow harmful elements in tidal zones to penetrate into the concrete. This will accelerate the corrosion rate, especially at high loading conditions.

DOI:

10.14359/3818


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