Repair Evaluation Maintenance And Rehabilitation Research Program Applications Of Roller Compacted Concrete In Rehabilitation And Replacement Of Hydraulic Structures

Although roller compacted concrete (RCC) was primarily developed for rapid, economical construction of new dams, the case histories reported herein show that it has been used extensively in remediation projects at existing hydraulic structures. These case histories were compiled to illustrate the versatility of RCC in repair, rehabilitation, and replacement of hydraulic structures. RCC applications include increasing existing spillway capacities; construction of new service, emergency, and combination spillways; repair of spillways, outlet tunnel, and lock floor; overtopping and scour protection for rock fill timber crib and embankment dams; seismic strengthening; increasing sliding stability; breach repair; and replacement of rock fill timber crib, earthfill embarkment, and concrete dams. The basic properties of RCC (high strength, low permeability, and high erosion resistance compared to nonstabilized materials) together with low cost, rapid and relatively simple construction methods, and proven performance make it particularly attractive for remediation of hydraulically deficient embankment dams. Depending on the complexity of placement and total quantity of material required, the cost or RCC typically ranges from 25 to 50 percent less than conventionally placed concrete. These savings are primarily the result of reduced costs for forming, placing, and compacting RCC. Also, the reduced construction time typical of RCC contributes significantly to its lower cost. Rapid construction is a major advantage in repair of hydraulic structures where delays and shutdowns can cause significant losses to the user. Also, rapid construction minimizes the impact of bad weather and reduces the potential for adverse environment impact in the vicinity of project sites.

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.

Presented are the results of a program conducted to identify the repair methods and materials currently being used to repair and rehabilitate concrete structures deteriorating as a result of cracking and spalling. These repair methods and materials were evaluated for their applicability to the in situ repair of concrete hydraulic structures. From this evaluation, the following three repair techniques were identified as best suited for in situ repair procedures: pressure injection, polymer impregnation, and addition of reinforcement. Case histories illustrating the application of each technique are presented. Recommendations are made for work to be performed to make these systems more applicable to the repair of hydraulic structures. Keywords: Concrete, Cracking, Hydraulic structures, In situ repair, Polymer impregnation, Post reinforcement, Pressure injection, Spalling.

Two computerized data bases, (a) structure-description and (b) damage and repair, were compiled. The structure-description data base contains basic information (location, category, age, purpose, etc.) on 766 projects. The damage and repair data base contains information on the current condition of the concrete in the Corps' civil works structures as determined through detailed reviews of over 2000 periodic inspection reports. To assist in the analysis, a number of computer programs were developed to manipulate and search the data bases. This analysis concentrated on the types of deficiencies observed, the cause (if reported), location within the structure, and degree of damage. Also, if the deficiency had been repaired, the material or technique or boh that were used and the performance were analyzed. This identification and assessment of problems relating to evaluation, maintenance, and repair of concrete will provide guidance in developing and establishing priorities for research in the Repair, Evaluation, Maintenance, and Rehabilitation (REMR) Research Program. Originator-supplied keywords: Causes of concrete deficiencies; Concrete structures; Condition evaluations; Damage to concrete; Deficiencies in concrete; Hydraulic structures; Maintenance of concrete; Repair of concrete; REMR (Repair, Evaluation, Maintenance, and Rehabilitation) Research Program.

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.

The field of Concrete Repair and Rehabilitation is gaining importance in view of its positive impacts in terms of socio-economic benefits and environmental sustainability. Due to growing importance of this field, many engineering colleges have included the subject of concrete repair and rehabilitation in the senior undergraduate and postgraduate course curriculums of civil engineering. This book is an earnest attempt to help students of civil engineering in enhancing their understanding and awareness about critical elements of repair and rehabilitation of concrete structure. The content is organised in such a way that it fulfils the academic needs of the students. This text attempts to dovetail all important aspects such as causes of distress, assessment and evaluation of deterioration, techniques for repair and rehabilitation along with selection of repair and rehabilitation materials and other important aspects related to preventive maintenance and rehabilitation/structural safety measures. The primary objective of this textbook is to guide students to: • Understand the underlying causes and types of deterioration in concrete structure • Learn about the field and laboratory testing methods available to evaluate the level of deterioration. • Get well acquainted with options of repair materials and techniques available to address different types of distress in concrete structure. • Grasp the knowledge of available techniques and their application for strengthening existing structural systems.

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).

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.

Prior to 1988, the general approach to lock wall rehabilitation was to remove 1 to 3 ft of concrete from the face of the lock wall and replace it with new air-entrained concrete. One of the most persistent problems using this approach was cracking in the replacement concrete. Since that time, a new rehabilitation method using precast concrete as a stay-in-place form for the replacement concrete has been developed. This rehabilitation method was used initially at Lock 22 on the Mississippi River and more recently at Troy Lock on the Hudson River. This report is a product of the after-action study performed on the use of precast concrete stay-in-place forming system for lock chamber rehabilitation at Troy Lock and comparison with previous cast-in-place repairs. Listed herein is pertinent background information, design criteria, panel details, production data, installation details, and quality and economic comparisons with cast-in-place rehabilitation. A separate documentary video of precast concrete panel product and installation was also produced as part of the after-action study. The precast system used at Troy Lock was installed at a cost slightly lower than that of cast-in-place systems used previously, but with substantial improvements in appearance, durability, speed of construction, and extent of cracking.