| Title |
Author |
Description and Summary |
Links |
| Epoxy Resins and Polyurethane Foams for Low Pressure Injection Crack Repair |
Concrete Repair Bulletin |
The question often arises as to which is better in concrete crack repair: epoxy or polyurethane foam. If the crack needs to be structurally repaired and the area needs to be as strong or stronger than the concrete around it, the answer is simple: epoxy.
The answer is less simple if the crack needs only to be repaired to prevent water leaking through it. Either can accomplish this task, and applicators typically choose the material they are most experienced with. |
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| CRACK REPAIR METHOD: EPOXY INJECTION |
REMR Research Program |
This method can be used to repair cracks as narrow as 0.002 in. The method generally consists of drilling holes at close intervals along the cracks, in some cases installing entry ports, and injecting the epoxy under pressure. For massive structures, an alternative procedure consists of drilling a series of holes, usually 7/8 in. in diameter, that intercept the crack at a number of locations. Typically, holes are spaced at 5-ft intervals. |
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| CONCRETE REPAIR BY EPOXY INJECTION |
Ohio State |
This specification covers the repair of dry, moist or wet cracks of fractures [50 to 2500 micrometers(2 to 100 mils) in thickness] in reinforced concrete members by means of an epoxy injection system. This system shall consist of a paste epoxy used to seal the surface cracks and an injection epoxy used under low pressure [1400kPa (200 psi) max.] to penetrate and fill the cracks and bond the crack surfaces together. Material for each epoxy shall consist of a two-component modified resin bonding system. The unmodified resin shall be known as Component A and the hardener as Component B. |
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| REPAIR CRACKS IN CONCRETE THROUGH INJECTION |
General Polymers |
The scope of this report includes: The review of why concrete cracks and the different methods or treatment(s) of cracks, from epoxy injection to bridging with elastomeric stretch coats to ignoring of them. The detailed repair procedures listed in this paper were originally developed for and presented to the PCI Quality Control Committee as the recommended repair procedures for concrete elements. |
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| EPOXY INJECTION FOR CRACKED CONCRETE AND SPALL REPAIR |
Anon |
A step by step seven page guide to the use of epoxy injection for the repair of cracked concrete and spalls. |
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| Evaluation of Injection Materials for the Repair of Deep Cracks in Concrete Structures. Repair, Evaluation, Maintenance, and Rehabilitation Research Program |
WISS JANNEY ELSTNER AND ASSOCIATES NORTHBROOK IL |
Wiss, Janney, Elstner Associates, Inc., was requested by the U.S. Army Corps of Engineers to perform a laboratory study to evaluate injection materials for the filling and repair of deep, narrow cracks in massive concrete structures. The emphasis of this study was on epoxies; however, high-molecular- weight methacrylates, ultrafine cements, and polyurethanes were also considered. A laboratory test program was developed to evaluate the properties that are considered to be important for injection materials. These properties included viscosity, surface tension, gel time, penetration, and bond strength to wet concrete. A literature survey and telephone interviews were performed prior to selecting the materials for testing, and a spreadsheet was constructed to aid in choosing the materials to be tested. This report also includes the literature survey and laboratory test data. The objective of this proposed research is to determine the most promising products (materials), equipment, and procedures available that could most effectively be used to cause the material to most deeply and uniformly penetrate and "heal" existing cracks in massive hydraulic structures. |
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| REPAIR AND REHABILITATION OF BRIDGE COMPONENTS CONTAINING EPOXY-COATED REINFORCEMENT |
Sohanghpurwala, A A; Scannell, W T; Hartt, W H |
The primary goal of this effort was to address the anticipated need for premature repair and rehabilitation of concrete bridge elements containing epoxy-coated rebar (ECR). Laboratory, test yard, and field studies were conducted to evaluate and validate applicable strategies. The performance of each strategy was judged by the level of corrosion protection afforded in and outside the repair area. Based on the results of this effort, credible information available in literature, and the collective experience of the research team, a decision matrix was developed. The decision matrix matches appropriate repair and rehabilitation strategies to the damage mode, present condition, environmental exposure, and future propensity of corrosion. The evaluation of strategies was subdivided into two categories, one applicable to the mitigation of corrosion in cracks and the other to delaminations and spalls. Several possible combinations of an epoxy injection material and two corrosion inhibitors were evaluated for corrosion mitigation in both corrosion and non-corrosion induced cracks. Injection of cracks was accomplished using bisphenol A and polyamine curing agent. Of the two surface applied (migrating) corrosion inhibitors used, one contained water based amine and an oxygenated hydrocarbon and the other contained calcium nitrite as the active agent. None of the repair strategies evaluated in this category exhibited any ability to provide protection against corrosion in the two spheres of interest, i.e., directly at the crack and the area adjacent to the cracks. Various combinations of three patch materials [pre-bagged portland cement concrete (PCC), pre-bagged polymer modified silica fume concrete, and Class III PCC], three rebar coatings (epoxy coating, water based epoxy resin/portland cement coating, and water based alkaline coating with corrosion inhibitor), and four corrosion inhibitors (water based amine and an oxygenated hydrocarbon migrating corrosion inhibitor, water based amine and an oxygenated hydrocarbon admixture, calcium nitrite admixture, and a multi-component corrosion inhibitor and concrete densifier admixture) were used in the evaluation of repair strategies applicable to delaminations and spalls. No benefit was discernable from the use of admixed and migrating corrosion inhibitors in repair areas and/or areas adjacent to the repair. The best response from a corrosion protection standpoint was demonstrated by a high resistance, low permeability silica fume modified patch material and an epoxy rebar coating compatible with ECR in the repair area. The water based alkaline coating with corrosion inhibitor showed promise in providing protection in the repair area. Impressed current cathodic protection applied to slabs for over 7.2 years successfully mitigated corrosion. The control slabs continued to corrode and experience corrosion induced damage, whereas, the cathodically protected ones did not suffer corrosion induced damage. Also, the current densities used to protect black reinforcing steel were found to be adequate to protect ECR. |
Document |
| Concrete Penstock Liner Damage Repaired with Crack Injection |
Anon |
In a large concrete penstock liner in Central California, severe lateral and radial cracks as well as leaking control joints were repaired successfully with a high strength epoxy injection adhesive. An earthquake started the damage in 1964, less than one year after the concrete liner had been constructed. This article reports the repair of this extensive damage with crack injection techniques. |
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| TESTING AND ASSESSMENT OF EPOXY INJECTION CRACK REPAIR FOR RESIDENTIAL CONCRETE STEM WALLS AND SLAB-ON-GRADE |
NAHB Research Center, Inc |
This research report addresses the performance of epoxy injection crack repair in plain (i.e., unreinforced or lightly reinforced) concrete stem walls and slab-on-grade floors found in typical single-family residential construction. While the research is intended to address the efficacy of repairs in the context of possible seismic damage, the issue of cracked foundations and floor slabs has a much broader association with housing performance problems. In fact, it is ranked among the most common home warranty claims and home builder concerns [1] [2]. Unfortunately, there is little data regarding the effectiveness or appropriateness of various repair methodologies for plain, residential concrete foundations and floor slabs. |
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| INJECTION BOLTS TO REPAIR OLD BRIDGES |
A.M. Gresnigt, Delft University of Technology, The Netherlands |
In 1996 an old riveted steel bridge in Oranienburg near Berlin had to be repaired because of severe corrosion in the web of the main girders. For several reasons it was decided to apply injection bolts to connect new plates at the corroded areas of these webs. German authorities requested the verification of the long duration creep resistance. To that aim, test specimens were made at the construction site and creep tests were started at Delft University at room temperature and at elevated temperature (70 degrees Celsius). These tests are still running. The paper describes the first application of injection bolts in Germany to repair steel bridges. Results of the long duration creep tests are given. These tests indicate that the design bearing resistance of the resin could be increased from the present 130 N/mm2, e.g. till 200 N/mm2. |
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| HR-177 Concrete Bridge Deck Repair Using Injected Epoxy Resin |
Iowa State |
Maintenance of spalled bridge decks requires constant surveillance and the commitment of considerable manpower and equipment by maintenance forces. Maintenance cost for deck repair was $68,000 in Fiscal Year 1977 and $83,400 in Fiscal Year 1978. Patching of spalled areas with bituminous material is a temporary repair, at best. It will help reduce traffic impact loadings on the structure but will do nothing to prevent further deterioration of the decks. It is usually noted that concrete around the spalled area delaminates (or is delaminated at the time the bituminous material is placed) this, in turn, spalls increasing the area of deterioration. Research funds were approved for the purchase of equipment designed to proportion and inject epoxy resins into delaminated areas of bridge decks. Through investigation and refining of this process, it was anticipated that a maintenance procedure would be developed to delay spalling of bridge decks by "gluing down" delaminated areas before spalling occurred. Results to date would indicate that using a machine for proportioning and pumping epoxy into delaminated areas to delay spalling in bridge decks is a viable maintenance procedure when large delaminated areas are present. Those instances that seem most adaptable to epoxy injection are bridges that have developed delaminated areas but do not exhibit very much spalling. |
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| REPAIR OF EARTHQUAKE-DAMAGED BRIDGE COLUMNS |
D. E. Lehman, S. J. Elkin, A. M. Nacamuli, and J. P. Moehle |
Columns supporting bridge structures may be expected to respond inelastically during strong earthquake shaking. Restoration to serviceable conditions may require repair or replacement of damaged regions, which may entail considerable cost and operational delay. To evaluate the feasibility of available repair techniques, an experimental study to evaluate repair techniques for damaged bridge columns was undertaken. The original columns were reinforced with spirals conforming to modern bridge requirements for regions of high seismic risk. Three of the test columns were severely damaged; the fourth column was moderately damaged. Repairs for the severely damaged columns used headed reinforcement, mechanical couplers, and newly cast concrete. The moderately damaged column was repaired by cover replacement and epoxy injection. The success of each scheme was evaluated by comparing behavior of the repaired column with that of the original column as well as the repair intent. |
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| Injection of porous mass concrete with cement-based suspension grouts |
Harald Wildner |
Until 1930 non reinforced concrete structures were built using untreated and unwashed gravel and less cement with insufficient compacting methods. As a result of seepage through the concrete over many years the cement matrix is panned out. These structures exhibit large voids and gravel pockets, which may be considered as pore cavities on the one hand, and on the other hand, may also act as gaps (concrete joints). The rehabilitation of these structures represent an ideal area of application for the injection with cement-based suspen-sion grouts, with the aim of sealing and strengthening. |
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| INVESTIGATIONS OF CONCRETE BOREHOLES FOR BONDED ANCHORS |
Roland Unterweger and Konrad Bergmeister |
The use of chemical bonded anchors has increased over the last years due to diminished costs, time and simply of installation. The present paper considers the modelling of chemical bonded anchors. |
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| Crack Injection: A Permanent Solution for Stopping Leaks |
Concrete Network |
Description:
As most homeowners with poured-in-place concrete foundations can attest: Cracks in basement walls are a fact of life. These cracks?due to drying shrinkage, thermal movement, and other causes?usually are minor and result in few problems. But over time, even minor cracks can grow larger and cause big headaches, such as loss of structural integrity or, more commonly, water leakage. The good news is that in most cases homeowners can now have these cracks fixed permanently?without the need for costly, disruptive excavation?using low-pressure injection of epoxy or polyurethane foam repair materials. |
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