Repair, Evaluation, Maintenance, and Rehabilitation Research Program: Evaluation of Concrete Mixtures for Use in Underwater Repairs
Repair, Evaluation, Maintenance, and Rehabilitation Research Program: Evaluation of Concrete Mixtures for Use in Underwater Repairs

Author: Billy D. Neeley

Publisher:

Published: 1988

Total Pages: 134

ISBN-13:

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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.

Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Laboratory Evaluation of Concrete Mixtures and Techniques for Underwater Repairs
Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Laboratory Evaluation of Concrete Mixtures and Techniques for Underwater Repairs

Author:

Publisher:

Published: 1990

Total Pages: 90

ISBN-13:

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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.

Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Underwater Repair of Concrete Damaged by Abrasion-Erosion
Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Underwater Repair of Concrete Damaged by Abrasion-Erosion

Author:

Publisher:

Published: 1991

Total Pages: 333

ISBN-13:

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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.

Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Review of the State of the Art for Underwater Repair Using Abrasion-Resistant Concrete
Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Review of the State of the Art for Underwater Repair Using Abrasion-Resistant Concrete

Author: GERWICK (BEN C) INC SAN FRANCISCO CA.

Publisher:

Published: 1988

Total Pages: 42

ISBN-13:

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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).

Repair, Evaluation, Maintenance, and Rehabilitation Research Program: In Situ Repair of Deteriorated Concrete in Hydraulic Structures Laboratory Study
Repair, Evaluation, Maintenance, and Rehabilitation Research Program: In Situ Repair of Deteriorated Concrete in Hydraulic Structures Laboratory Study

Author: R. P. Webster

Publisher:

Published: 1988

Total Pages: 34

ISBN-13:

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Presented are the results of a laboratory-scaled test program conducted to evaluate the effectiveness of (a) pressure injection, and (b) polymer impregnation repair techniques for use in in situ repair of cracked concrete hydraulic structures. In general, the test results indicate that pressure injection can be used to effectively restore the integrity of air-dried and water-saturated cracked concrete. Polymer impregnation can be used to improve the quality of the concrete surrounding the crack network. However, its effectiveness in sealing the crack network is dependent upon the viscosity of the impregnant being used. The two methods can be used in conjunction to effectively repair and improve the overall quality of the structure to be rehabilitated.