Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Underwater Repair of Concrete Damaged by Abrasion-Erosion PDF Download
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Author:
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ISBN:
Category :
Languages : en
Pages : 333
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Book Description
The grinding action of waterborne debris circulating in concrete stilling basins, open channels, navigation locks, and other hydraulic structures can lead to abrasion damage several feet in depth. Damaged areas need to be periodically repaired to ensure the functionality and safety of the hydraulic facility. Traditionally, these repairs have been carried out after dewatering the damaged area; however, such practice can interfere with the operations of the facility and can prove to be very costly. Therefore, it is desirable to carry out the repairs while the damaged portion of the structure is submerged. The objective of this research was to develop concrete mixtures and placement methods to repair typical scour holes underwater. Approximately 70 concretes were evaluated to optimize mixture proportions. The four most promising fluid concretes and one control concrete were selected to fill small and relatively shallow depressions underwater using the conventional tremie and the proposed inclined tremie methods. Concrete was placed in the laboratory in a test box with the bottom especially shaped to simulate a small scour hole. Surface profiles and in-place mechanical properties of eight underwater-cast slabs and one slab that was cast above water were evaluated to compare concrete mixtures and placement techniques.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 333
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Book Description
The grinding action of waterborne debris circulating in concrete stilling basins, open channels, navigation locks, and other hydraulic structures can lead to abrasion damage several feet in depth. Damaged areas need to be periodically repaired to ensure the functionality and safety of the hydraulic facility. Traditionally, these repairs have been carried out after dewatering the damaged area; however, such practice can interfere with the operations of the facility and can prove to be very costly. Therefore, it is desirable to carry out the repairs while the damaged portion of the structure is submerged. The objective of this research was to develop concrete mixtures and placement methods to repair typical scour holes underwater. Approximately 70 concretes were evaluated to optimize mixture proportions. The four most promising fluid concretes and one control concrete were selected to fill small and relatively shallow depressions underwater using the conventional tremie and the proposed inclined tremie methods. Concrete was placed in the laboratory in a test box with the bottom especially shaped to simulate a small scour hole. Surface profiles and in-place mechanical properties of eight underwater-cast slabs and one slab that was cast above water were evaluated to compare concrete mixtures and placement techniques.
Author: Billy D. Neeley
Publisher:
ISBN:
Category :
Languages : en
Pages : 134
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Book Description
Concrete mixtures were evaluated to determine which were most suited for placement underwater in thin lifts. The concretes were proportioned to have good workability, good abrasion erosion resistance, and good resistance to washing out of the cement paste. High-range water reducers (HRWR) were used to increase the workability and permit the use of low water cement ratios (W/C) to increase the resistance to abrasion erosion. Low W/C, silica fume, and antiwashout admixtures (AWA) were used to increase the resistance to washout. A washout test was used to determine the relative amount of cement paste lost when the concrete is exposed to a large volume of water. The two-point workability test was used to evaluate the relative workability properties of each mixture. The slump and air content were also measured for most of the mixtures. The test method for abrasion erosion resistance of concrete (underwater method) was used to determine the abrasion erosion resistance of each mixture. The results of these tests were used to determine the combination of materials necessary to produce concrete with the desired properties. Significant correlations that exist between the two-point measurements and washout measurements were examined. The effects that W/C, HRWR's, AWA's, fly ash, and silica fume have upon washout resistance and abrasion-erosion resistance were examined.
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ISBN:
Category :
Languages : en
Pages : 90
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Concrete mixtures were placed underwater using six placement techniques to (a) examine the cohesive and flow parameters of selected concrete mixtures under different placement situations, (b) estimate those parameters necessary for successful underwater placement, (c) examine the quality of bonding of the repair concrete to the existing concrete, and (d) examine the effect of underwater placement upon the abrasion resistance of the concrete. A washout test was used to determine the relative amount of cement paste lost when the concrete is exposed to a large volume of water. The two-point workability test was used to evaluate the relative workability properties of the concrete. The slump, tremie flow, and air content were also measured. The test method for abrasion-erosion resistance of concrete (underwater method) was used to determine the abrasion-erosion resistance of each concrete. A point-load test for tensile strength was used to determine the bond strength of the repair concrete to the existing concrete.
Author: Kamal Khayat
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 340
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Author: GERWICK (BEN C) INC SAN FRANCISCO CA.
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ISBN:
Category :
Languages : en
Pages : 42
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Concrete hydraulic structures that are subjected to severe abrasion require periodic inspection, evaluation, and repair. Not only are these procedures costly and sometimes disruptive, but repeated repairs also make guaranteeing the integrity of the underlying layers difficult. This review was conducted, on an international level, to identify new techniques and potential areas of research that might lead to more abrasion-resistant materials and more effective repair methods and that would avoid the high cost and disruptions associated with dewatering. Topics of study in the review include: (a) underwater inspection, (b) concrete mixtures, (c) underwater placement of concrete, (d) underwater compaction of concrete, (e) polymer concretes and coatings, (f) surface preparation, and (h) support vehicles. Keywords: Concrete admixtures, Hydro-valve, Pneumatic valves, Polymer concrete, Robotics, Support vessels.(jes).
Author: Dennis L. Bean
Publisher:
ISBN:
Category :
Languages : en
Pages : 68
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The surfaces of many of the Corps' concrete structures are subject to deterioration due to freezing and thawing, weathering, chemical attack, erosion, and other destructive mechanisms. Surface treatment of the concrete with a material to retard action of the forces is one way to reduce the rate of or eliminate deterioration. In the past, various surface treatments have been applied to concrete; some were successful, while others failed. In most cases the failures were due to either selection of the wrong surface treatment material or improper application. There is a need to evaluate various surface treatments to determine which would offer the best protection and what would be the proper ways to apply them. The objective of this study was to obtain information on the types of current surface treatment materials available, chemical compositions, and properties, and the performance of these materials in service conditions. Keywords: Abrasion, Erosion, Coating, Hydraulic structures, Concrete deterioration, Sealers, Surface treatments, Stone consolidants, Vapor transmittance.
Author: Ben C. Gerwick, Inc
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ISBN:
Category :
Languages : en
Pages : 0
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Author: Sandor Popovics
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ISBN:
Category : Concrete
Languages : en
Pages : 0
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Author:
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ISBN:
Category :
Languages : en
Pages : 104
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Book Description
This study documents the current practices for overlaying horizontal concrete surfaces as a first phase in the development of performance criteria for concrete overlays. The case histories presented were typically for overlays completed within the last 10 years and located at Corps of Engineers civil works projects. Overlays documented included bonded conventional, low-slump, fly-ash, silica-fume, polymer-modified, and fiber-reinforced concretes. Unbonded overlays were also documented. Although the information obtained for each case history varied and was sometimes limited, an attempt was made to provide the following basic information for each repair: (a) project description, (b) cause and extent of damage, (c) description of repair materials and procedures, (d) cost, and (e) performance of repair. The extension of service life resulting from using one type of overlay in lieu of another was not evident in the case histories examined, with the exception of where fiber-reinforced concrete was used to resist abrasion erosion (repair failed). Shrinkage and reflective cracks that develop in polymer-modified concrete overlays and overlays containing polypropylene fibers are more likely to be smaller in width and length than those of similiar cracks in conventional and low-slump concrete overlays. Cracks in concretes containing fibers are generally smallest.
Author:
Publisher:
ISBN:
Category : Public works
Languages : en
Pages : 12
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