1、Standard Specification for Use of Protective Sealers for Portland Cement Concrete AASHTO Designation: M 224-91 (2014) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001TS-4c M 224-1 AASHTO Standard Specification for Use
2、of Protective Sealers for Portland Cement Concrete AASHTO Designation: M 224-91 (2014) 1. SCOPE 1.1. This guide includes the selection factors for and use of protective sealers for highway purposes to be applied to hardened concrete for the purpose of protecting new concrete or prolonging the life o
3、f sound, in-service concrete. Information in this guide is not applicable to the repair of badly deteriorated concrete. 1.2. Sealers may be divided into two basic types: coatings, which remain on the surface; and penetrants, which penetrate into the concrete to some measurable depth. 1.3. There are
4、strong differences of opinion about the effectiveness and durability of some types of sealers under actual service and conditions as opposed to laboratory tests that may show the sealers to be effective. It must also be understood that there can be considerable differences in performance of material
5、 from different manufacturers for the same type of sealer. 1.4. The values stated in SI units are to be regarded as the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: M 233, Boiled Linseed Oil Mixture for Treatment of Portland Cement Concrete 2.2. ASTM Standard: D490, Standard Specification
6、 for Road Tar 2.3. Other Reports: Pfeifer, D. W., and M. J. Scali. Concrete Sealers for Protection of Bridge Structures. National Cooperative Highway Research Program Report 244. NCHRP, Transportation Research Board, Washington, DC, 1981, 138 pp. Munshi, S., and L. Millstein. Low Cost Bridge Deck Su
7、rface Treatment. FHWA/RD-84/001. Federal Highway Administration, U.S. Department of Transportation, Washington, DC, 1984, 70 pp. 3. SELECTION OF THE SEALER 3.1. A number of factors must be carefully considered when choosing a sealer. These factors include the following: 2015 by the American Associat
8、ion of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4c M 224-2 AASHTO 3.1.1. PurposeWill the sealer be used to waterproof the concrete or prevent the ingress of chlorides? A given sealer may be better suited to one or the other of th
9、ese purposes. 3.1.2. EffectivenessCoatings should form an impervious membrane tightly bonded to the concrete surface, while penetrants should seal the surface pores and fill the capillaries of the concrete. Sealers should maintain their protective properties through wide temperature fluctuations and
10、 when subject to all chemical and physical conditions at the site of use. 3.1.3. EconomyIt is desirable that the chosen sealer be low in initial cost. However, this should not take precedence over life-cycle costs; that is, cost should include consideration of frequency of reapplication necessary to
11、 maintain effectiveness. 3.1.4. TrafficSealers on traveled surfaces must not reduce the frictional properties of the concrete; some types may, with the use of a cover aggregate, increase the frictional properties. Coatings must be resistant to traffic wear; penetrants should be evaluated according t
12、o depth of penetration, because they will wear away with the concrete. If an overlay will be placed after sealer application, wear will not be a factor. 3.1.5. Application and CuringEase and simplicity of application without the use of special skills or equipment is desirable, but not critical. It i
13、s usually advantageous for a material to cure or dry in a few hours so that neither damage by rain nor lengthy closure of the facility is necessary. 3.1.6. ColorIf color of the treated concrete is important, test blocks should be treated with candidate materials for evaluation prior to use. 3.1.7. S
14、afetySafety should be carefully considered. Several of the materials involve toxic or hazardous components. Others may have to be heated. Refer to Section 7 for details. 3.1.8. Adverse ConditionsRarely, it may be necessary to apply the sealer under adverse conditions such as low ambient temperatures
15、 or dampness. In these cases, a coating must be chosen that would offer some chance for reasonable success. Experience and the manufacturers recommendations should be used in determining whether or not conditions are suitable for application. 4. SEALER TYPES 4.1. Sealers commonly used for concrete a
16、re two general types: (1) coatingsthose that remain on the surface and tend to build up a layer or membrane of some thickness, and (2) penetrantsthose that penetrate the concrete, forming an interior or subsurface barrier. As an aid in the choice of a material suitable for a specific application, th
17、e more commonly used sealers are discussed in Sections 4.2 through 4.9. 4.1.1. ReferencesAdditional sources of information regarding sealers are: 4.1.1.1. AASHTO StandardM 233. 4.1.1.2. ASTM StandardD490. 4.1.1.3. Other ReportsNational Cooperative Highway Research Program Report 244 and Federal High
18、way Administration Report No. FHWA/RD-84/001. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4c M 224-3 AASHTO 4.2. Epoxy ResinEpoxy may be considered a coating or penetrant depending on the percenta
19、ge of solids in the formulation. The two-component epoxy resin system forms a sealer that is tough, hard, and resistant to chemicals that normally attack roadway surfaces and weathering. Before curing, epoxy has a tendency to “pinhole,” permitting later entrance of water and salt solution into the u
20、nderlying concrete. Experience indicates the use of suitable primer may alleviate this. Also, application of the material during that part of the day when the concrete is cooling helps prevent pinholing. If the epoxy is formulated as a coating, flaking or peeling can occur due to a difference in the
21、rmal expansion of the coating and the concrete or to improper surface preparation. The protective film formed by these materials reduces frictional properties. The use of a suitable aggregate spread over the freshly applied coating greatly improves frictional properties. Epoxy systems require skill
22、in handling and application. It is essential that the recommendations of the manufacturer be followed precisely for both application procedures and equipment. Special materials will be required for cleaning of equipment. Most persons are allergic to contact with epoxies; therefore, recommended safet
23、y practices must be followed carefully. 4.3. Coal Tar EpoxyCoal tar resins form surface coatings that are hard and durable. They are relatively resistant to many corrosive and abrasive environments and are durable under exposure to weather. They appear to function best on roadway surfaces when fille
24、d with sand and other suitable aggregate. These materials contain curing agents and strong solvents that may cause allergic reactions. They must be handled with caution; recommended safety precautions must be followed. These materials are naturally dark to black in color and may not be desirable in
25、some locations. 4.4. Linseed OilLinseed oil applied to concrete surfaces penetrates and forms a partial barrier to water. It is therefore not subject to traffic abrasion and it does not materially change the original frictional properties of the concrete if applied at the proper rate. Linseed oil ma
26、y be applied as solution. Experience indicates that the solutions are more effective and longer lasting than are emulsions, probably due to redispersion of the linseed oil applied as an emulsion, when subjected to salt solutions. These materials are easily applied with simple, readily available equi
27、pment and require no specialized knowledge or skills. Safety hazards are minimal; only routine precautions for handling and using flammable liquids are necessary with the solvent types. For best results on new concrete surfaces, the concrete should be allowed to dry for about 30 days prior to the ap
28、plication of the compound. To remain effective, concrete surfaces should be recoated annually for 2 years followed by a biannual or triannual schedule of treatment. 4.5. Tar Primer and SealTars applied to concrete surfaces form a coating that is an effective surface barrier to water. Usually a prime
29、r must be used because of wetting difficulties on concrete. These materials may be applied in solution or softened by heat. Due to relatively poor resistance to sunlight, weather, and abrasion, these materials should be covered by a suitable bituminous mix. 4.6. Silanes and SiloxanesThese materials
30、are classified as penetrants. Unlike other sealers, these materials do not truly seal the concrete, but react chemically with the concrete, both at the surface and in pores and capillaries, to form a hydrophobic layer, which is repellant to water. They can be applied in one coat. 4.7. MethacrylatesT
31、hese materials may be described as a coating or penetrant depending on the formulation. Two coats are usually required to get proper sealing. The surface to be treated must be dry and free of oil, grease, and loose material. Time needed between coats will vary according to ambient temperature condit
32、ions. 4.8. Sodium SilicateThis material is a penetrant in the form of an aqueous solution. Concrete surfaces must be clean and dry at the time of application. The material should not be applied at temperatures below 4C (40F) or during rain. 2015 by the American Association of State Highway and Trans
33、portation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4c M 224-4 AASHTO 4.9. UrethaneThis material is classified as a penetrant or a coating depending on formulation. Two coats may be required. The concrete surface should be free of loose material, clean, and dry.
34、Some formulations should not be applied under high humidity conditions. (See manufacturers recommendation.) 5. SURFACE PREPARATION 5.1. Surfaces to which the sealers are applied may be new concrete or concrete that has been in service for some time. 5.2. Preparation of the surfaces will vary accordi
35、ng to the type of sealer being used. In all cases, the surfaces should be clean and free of all dirt, dust, and loose material. Old surfaces should have any oil or paint removed. The required degree of dryness of the concrete will vary according to the material being used; the manufacturers literatu
36、re should be consulted for this and other specific surface requirements. 6. SEALER PREPARATION AND APPLICATION 6.1. For best results, manufacturers recommendations should be followed in preparing and applying sealers for concrete. Common practices for the different materials follow: 6.1.1. Epoxy Res
37、ins and Coal Tar EpoxyAll materials should be within applicable temperature ranges before mixing. Thorough mixing of the components in the specified proportions is essential. No more should be mixed than will be used within the pot life of the materials. Small-batch mixing can best be done in clean,
38、 dry pails or disposable containers using a mechanical stirrer, although with care, hand mixing is acceptable. For large jobs, specialized continuous mixing equipment is available and should be used. 6.1.1.1. Application on small areas can readily be made by brush, roller, squeegee, hand sprayer, or
39、 other means. Power spray equipment is most satisfactory for covering large areas. 6.1.1.2. For most materials, the temperature of the concrete surface should be not less than 15C (60F). A satisfactory temperature range for the compound at application is 21 to 32C (70 to 90F). 6.1.1.3. Equipment use
40、d in application must be cleaned using solvent wash before setting of the epoxy. The solvent recommended by the manufacturer of the epoxy is best, but others may be satisfactory, such as toluene, trichloroethylene, etc. Use appropriate safety precautions when using these solvents. 6.1.2. Linseed Oil
41、Application of linseed oil may be readily accomplished by brush, squeegee, roller, hand sprayer, or power sprayer. The concrete surface should be dry and at a temperature of not less than 10C (50F) at the time of application. The rate of application should be specified. Two approximately equal appli
42、cations are best with a 24-h minimum drying time between applications. Cleaning of tools and equipment is easily accomplished by use of kerosene or other petroleum solvents. 6.1.3. TarsThese materials may be applied by power or hand spray, by brush, or by squeegee. The concrete surface to be treated
43、 should be dry and clean. The prime coat should be permitted to dry thoroughly before applying succeeding coats. Depending on the grade of tar selected, temperature of application will vary to provide the proper viscosity for application. 2015 by the American Association of State Highway and Transpo
44、rtation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4c M 224-5 AASHTO 6.1.4. Silanes and SiloxanesThese materials should not be applied at temperatures below 0C (32F) or when the temperature is expected to fall below 0C (32F) within 12 h of application. These mater
45、ials appear to penetrate best on a thoroughly dry surface. Application rate should range between 2.45 and 9.82 m2/L (100 and 400 ft2/gal) depending on surface texture and absorption. The recommended method of application may vary depending on the material. The manufacturers recommendations should al
46、ways be followed. The most common method of application is low-pressure airless spray, and most sealers require enough material to sufficiently saturate the surface of the concrete. 6.1.5. MethacrylatesDepending on the formulation, these materials should not be applied when the temperature is below
47、10C (50F). A primer is required for some formulations. The concrete surface must be dry. Application rates range from 2.45 to 9.82 m2/L (100 to 400 ft2/gal). Sealers should be applied as the manufacturer recommends. Common methods of application include spray, roller, brush, and squeegee. 6.1.6. Sod
48、ium SilicateThis material should not be applied at temperatures below 4C (40F). It may be applied by brush, squeegee, or spraying. After 3 to 6 h, the surface should be flushed with water, the flushing to be repeated at 24-h intervals for 72 h. The coverage rate is 4.91 to 7.36 m2/L (200 to 300 ft2/
49、gal). 6.1.7. UrethaneThis material can be applied in the temperature range of 4 to 38C (40 to 100F) with some formulations having an allowable application temperature as low as 8C (18F). The surface should be free of moisture. Coverage is in the range of 4.91 to 9.82 m2/L (200 to 400 ft2/gal). Sealers are best applied with either air atomized or conventional airless spray, although brush, roller, or squeegee may be used. Manufacturers recommendations should be followed. 7. SAFETY 7.1. The usual precautions exercised in the
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