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: 

SP126-16

Date: 

August 1, 1991

Author(s):

Harold Roper and Daksh Baweja

Publication:

Symposium Papers

Volume:

126

Abstract:

Corrosion of steel reinforcement within concrete structural elements is a major problem in both research and practice. Laboratory studies have been conducted on fundamental mechanisms of corrosion within concrete in the presence of high chloride and others under conditions of reduced alkalinity. However, little has been published on the interactive effects of these two conditions and the ways in which corrosion rates of steel in concrete are thereby influenced. These two conditions occur concurrently under many practical environmental exposures. This paper presents data on methodology used to determine corrosion rates of steel in concrete. Information on corrosion activities in both carbonated and high-chloride environments is presented with reference to mechanisms involved in breakdown of steel passivation. Interactive effects of the two conditions are examined for a range of concrete types and grades. The data suggest that for normal reinforced concrete structural elements, the interactive effects of carbonation and chloride ion ingress lead to much more rapid corrosion than where the two phenomena occur independently. The interactive effects of carbonation and chloride ions as they influence concretes under service conditions are discussed. In particular, the reduction of carbonation rate in the presence of high-chloride ion concentrations is noted.

DOI:

10.14359/2177


Document: 

SP126-34

Date: 

August 1, 1991

Author(s):

N. A. Cumming, T. F. Rogers, and A. P. Joseph

Publication:

Symposium Papers

Volume:

126

Abstract:

The Arthur Laing Bridge was constructed in 1975. At a relatively early age of about 6 years it began to suffer damage due to corrosion of the deck reinforcement. A major rehabilitation and resurfacing program was implemented in 1987, which included the installation of a cathodic protection system on about 45 percent of the 21,200 mý deck. This is one of the largest installations of cathodic protection on a reinforced concrete bridge deck. The original deck was milled to a depth of 15 to 25 mm to remove chloride-contaminated concrete. A catalyzed titanium wire mesh anode system was installed on the milled surface after delaminations had been patched. Finally a 50 mm thick low-slump dense concrete overlay was placed. This paper describes the design and construction of the cathodic protection system. Technical details of the cathodic protection and overlay system and construction costs are also presented.

DOI:

10.14359/3790


Document: 

SP126-35

Date: 

August 1, 1991

Author(s):

K. Takewaka and T. Minematsu

Publication:

Symposium Papers

Volume:

126

Abstract:

The impressed current-type of cathodic protection was evaluated for controlling of marine concrete structures as follows: To establish criteria of cathodic protection on marine concrete structures, to develop a system that can distribute current uniformly to all reinforcement, and to investigate the over-protection problem that effects the bonding of reinforcement and durability of anode material. The application of the cathodic protection system for the rehabilitation of a harbor concrete structure in Japan was also examined.

DOI:

10.14359/3797


Document: 

SP126-32

Date: 

August 1, 1991

Author(s):

Magne and Steinar Helland

Publication:

Symposium Papers

Volume:

126

Abstract:

A part of the Statpipe Development Project is a landfill for two gas pipelines on the exposed western coast of Norway. The pipelines are placed inside a submerged concrete tunnel that acts as an underwater protecting bridge over the rocky sea bed. The 590 m long tunnel was cast in five separate elements produced in two dry docks. The tunnel starts at a water depth of 30 m and ends up at water level. The tunnel elements were produced and placed during the summer of 1982. The splash zone element encompassed the following characteristics; 400 kg ordinary portland cement and 32.5 kg silica fume per m3 concrete. The water-cement-sand ratio was 0.36, the slump value was approximately 200 mm, and the 28-day cube strength was approximately 78 Mpa. After 7 years in service, cores were drilled from the splash zone element. The testing of the cores included compressive strength, capillary absorption, chloride profile, thin-section analyses, x-ray diffraction, scanning electron microscopy, and element analysis. The results indicate that in such a low-porous concrete, the reaction products between seawater and cement paste will fill up the original low porosity and tighten the concrete so that the ingress of chlorides will cease. For concrete exposed to seawater, ingress of clorides and risk of reinforcing bar corrosion represents the most severe problem. The tightening effect of seawater in such a high-performance concrete seems to reduce this problem to a minimum.

DOI:

10.14359/2343


Document: 

SP126-41

Date: 

August 1, 1991

Author(s):

C. N. MacDonald

Publication:

Symposium Papers

Volume:

126

Abstract:

Polypropylene and steel fiber reinforced concretes have been used by the author in chemical plant environments since 1980. The applications have been primarily for slabs on grade but have also included grade beams, slab overlays, equipment foundations, pedestals, pump pads, containment barriers, and pile caps. This paper compares durability performance of nonfiber reinforced concrete and fiber reinforced concrete in chemical plant locations in Michigan and Kentucky. The primary durability indicator is crack-free, long-wearing concrete. The results of these durability performances are applicable to the concrete industry in general, and specifically to the placement of concrete in chemical plants. The results indicate that the best durability performance was from concrete reinforced with steel fiber, then polypropylene fiber, and finally nonfiber reinforced concrete. The reasons underlying this performance are explored from the perspective of what is needed for scheduling, cost, and performance of concrete in the various projects, and environments to which the concrete is subjected. This investigation was conducted first by the proper design of the concrete mix proportions, and then by follow-up with field surveys, interviews, and calculations.

DOI:

10.14359/3513


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