EPOXY AND ADHESIVES -1 EPOXY RESIN ADHESIVE SYSTEMS
This section addresses epoxy resin adhesive systems to be used for bonding hardened concrete, fresh concrete, or other materials to hardened concrete. The classification of these epoxy systems is consistent with ASTM C881, but is limited to epoxy Types I – V and Grades 1 – 3. Use e poxy resin adhesive systems found on the NCDOT APL .
Epoxies are classified using a Type/Grade nomenclature (e.g. Type I, Gr. 1), where Type is defined by the application and determines performance requirements and Grade correlates to viscosity. Any combination of Type and Grade of epoxy listed below are permitted for evaluation and acceptance on the APL. Types are defined as :
epoxy mortar where hardened concrete or other materials are bonded to hardened concrete. Th is epoxy type is suitable for non- structural crack repairs where the epoxy is poured on the surface to penetrate cracks by gravity.
concrete to hardened concrete.
Surface Treatments (HFST)) or as a binder for mortar repairs of contact surfaces in traffic areas .
epoxy mortar where hardened concrete or other materials are bonded to hardened concrete. This application includes the installation of anchors, such as anchor bolts, dowel bars, threaded rods, rebar, and other fixtures in hardened concrete. This epoxy type also provides a high modulus that when combined with the desired viscosity, makes it suitable for pressure injection into concrete cracks .
is bonded to hardened concrete. Grades are defined as :
Many epoxies meet the requirements of more than one Type classification due to the material satisfying the physical property and performance requirements of multiple type classes. When epoxies meet the requirements of more than one Type classification, the epoxy will be listed with each of the Types it qualifies for, such as Type I/II, Gr. 2.
Epoxies shall conform to the requirements shown in Table 1081- 1 using the test methods described in Article 1081- 3. Epoxy systems that appear on the NCDOT APL have been verified to meet the performance requirements shown in Table 1081- 1. Further consideration of the installation requirements and environment is required when selecting an epoxy system for a particular application.
Type IV epoxy resin systems used for embedding anchors or other post-installed fixtures in hardened concrete shall be evaluated by the Contractor and verified by the manufacturer to ensure the pull -out strength of the anchor system in the proposed installed configuration provides a maximum of 125% of the yield load listed in the plans . “Anchor system” refers to the combined mechanical properties provided by the total assembly, which consists of the substrate material, the epoxy bonding material, and the anchor fixture, as a finished installation . Evaluation of the anchor system shall utilize a concrete compressi ve strength between 2,500 psi (minimum) and the design compressive strength of the concrete that the anchor will be installed in (maximum). The manufacturer of the selected Type IV epoxy system shall provide the Manufacturer’s Printed Installation Instructions (MPII), as described in ASTM E488, including directions on hole preparation, sizing, spacing, minimum installation depth for the type of anchor to be installed and the pull -out strength obtained. The Manufacturer’s MPII is accepted as certification that for the particular anchor grade, diameter and embedment depth specified, the anchor system will not fail by adhesive failure. Field testing may be required for adhesively anchored fixtures. List the properties of the adhesive on the container and incl ude density, minimum and maximum temperature application, setting time, shelf life, pot life, shear strength and compressive strength.
separate, settle or cause skinning during storage of the epoxy components. Do not use abrasive fillers such as alumina and silica flour. Do not use solvents. When mineral fillers are to be added during mixing, they shall be inert, readily dispersible and e xcept for sand, have fineness such that 99% of the material will pass a No. 325 sieve.
Therefore, to reduce spalling and peeling during temperature changes, avoid thick layers of pure epoxy. A 4:1 by weight sand- epoxy mortar has approximately the same coefficient of expansion as concrete.
clean, dry or damp surfaces free of standing water.
TABLE 1081 -1 PROPERTIES OF MIXED EPOXY RESIN SYSTEMS Property Epoxy Type I II III IV IV Viscosity (P) Grade 1, max Grade 2, min Grade 2, max 100 100 100 100 100 Consistency (in) Grade 3, max 1/4 1/4 1/4 1/4 1/4 Gel Time (min) 30A 30 15 30A Bond Strength (psi) Hardened to Hardened Concrete: 2 days (moist cure) 14 days (moist cure) Fresh Concrete to Hardened Concrete: 14 days
1000 1500
-
- -
1500
- 1500B
-
1000 1500
-
- -
1500 Absorption, 24 h, max, (%) 1 1 1 1 Thermal Compatibility - - pass Compressive Yield Strength, min, 7 days (psi) 8000 5000 - 10000 8000 Tensile Strength, min, 7 days (psi)C 5000 2000 2500 7000 6000 Elongation, min, 7 days (%)C 1 1 30 1
and dispensing equipment is used.
in lieu of bond strength value obtained by ASTM C882.
Determine the viscosity of the mixture in accordance with ASTM D2556 and ASTM C881.
Determine the consistency of a Grade 3 epoxy in accordance with ASTM C881 .
Determine the gel time of the mixture in accordance with ASTM C881.
Determine the bond strength in accordance with ASTM C882.
Determine the absorption in accordance with ASTM D570.
Determine the thermal compatibility in accordance with ASTM C884.
Determine the compressive yield strength in accordance with ASTM D695.
Determine the tensile strength and tensile elongation of the mixture in accordance with ASTM D638. Tensile strength and tensile elongation are also required for Grade 3 consistency epoxies though not required by ASTM C881.
All epoxy resin systems shall be on the NCDOT Approved Products List before use. Manufacturers choosing to supply material for Department jobs must submit an application through the Product Evaluation Program with the following information for each type and brand name:
manufacturer,
information, mixing directions, finishing directions, curing, clean -up and precautions/limitations,
& Audit Solutions program showing the pro duct meets the specifications of Table 21 -1. Products will remain on the NCDOT APL as long as the formulation and manufacturing process remain unchanged, and the product performs as intended in the field.
When materials on the NCDOT APL are furnished to a project, submit to the Engineer a Type 3 material certification in accordance with Article 106 -3 for each lot or batch delivered . When materials are furnished to the Bridge Maintenance Unit, the terms of acceptance will be listed in the bid solicitation. The Engineer reserves the right to reject any epoxy that does not perform adequately in the field.
Supply epoxy resin in two components, labeled as “Component A - Contains Epoxy Resin” and “Component B - Contains Curing Agent”, for combining immediately before use in accordance with the manufacturer’s instructions. Mark each container with the manufacturer’s name, NCDOT type, l ot or batch number, quantity, date of manufacture, shelf life or expiration date, color, mixing instructions, usable temperature range and hazards or safety precautions. Furnish the two components in separate non- reactive containers. Provide containers of such size that the proportions of the final mix can be obtained by combining a single container of one component with one or more whole containers of the other component.
Epoxies can irritate the eyes, skin and respiratory t ract. Therefore, wear chemical splash goggles, chemically -resistant gloves and protective clothing and boots when
handling epoxies. Respiratory protection is usually not needed if epoxies are mixed and applied in well- ventilated areas, but avoid prolonge d breathing of vapors. Follow all SDS instructions for proper use of these materials.
Stir parts A and B individually until each component is homogeneous. Use a separate stirrer for each component. Combine parts A and B, either by weight or volume, as specified in the manufacturer’s instructions. Stir the mixture vigorously, periodically scraping the sides and bottom of the container. Small quantities of epoxy usually require 2 to 3 minutes to mix homogeneously; 5- gallon quantities can take up to 10 minutes of mixing. Temperature affects the viscosity and pot life of epoxies. Most laboratory tests are conducted at 77°F. Higher temperatures render epoxies thinner and faster setting; lower temperatures induce higher viscosities and longer pot lives . Add sand or other fillers to liquid epoxies only after parts A and B have been thoroughly mixed. Stir in the sand or filler until all particles are completely coated.
Store epoxies at temperatures between 50°F and 90°F. Epoxy components exposed to the extremes of this range or outside this range should be conditioned to 77°F before mixing and blending. If heat is necessary, always use indirect methods such as hot water or a heated room to condition components. The Epox y Class, either A, B, or C as defined by ASTM C881, shall be used as a design basis when procuring epoxy for installation. Epoxy Classes define the epoxy performance across a range of substrate temperatures when the epoxy system is applied. For example, Class A epoxies, which are designed for applications below 40°F, will have viscosity and gel time values consistent with those shown in Table 25 -1 when applied to materials at temperatures below 40°F. Using the same material at 70°F could result in much shorter gel times and altered viscosity . Seal previously opened containers to be airtight. Unsealed containers can absorb moisture from the atmosphere, which can alter the chemical reaction of the mixture. -2 POLYESTER RESIN ADHESIVE
Polyester resin is used specifically for embedding dowel bars, threaded rods, rebars and other fixtures in hardened concrete. Polyester resin adhesive systems shall be evaluated by the Contractor and verified by the manufacturer to ensure the pull -out strength of the anchor system in the proposed installation configuration provides a minimum of 125% of the yield load listed in the Plan. “Anchor system” refers to the comb ined mechanical properties provided by the total assembly, which consists of the substrate material, the epoxy bonding material, and the anchor fixture, as a finished installation. Evaluation of the anchor system shall utilize a concrete compressive streng th between 2,500 psi (minimum) and the design compressive strength of the concrete that the anchor will be installed in (maximum). The manufacturer of the selected Type IV epoxy system shall provide the Manufacturer’s Printed Installation Instructions (MPI I), as described in ASTM E488, including directions on hole preparation, sizing, spacing, minimum installation depth for the type of anchor to be installed and the pull-out strength obtained. The Manufacturer’s MPII is accepted as certification that for the particular anchor grade, diameter and embedment depth specified, the anchor system will not fail by adhesive failure . Field testing may be required for adhesively anchored fixtures .
Package components of the adhesive in containers of such size that one whole container of each component is used in mixing one batch of adhesive. Use containers of such design that all of the contents may be readily removed, and are well sealed to prevent leakage. Furnish adhesive material that requires hand mixing in two separate containers designated as Component A and Component B. A self -contained cartridge or capsule will consist of two components which will be automatically mixed as they are dispensed, as in the case of a cartridge, or drilled into, as in the case of a capsule. Clearly label each container with the manufacturer’s name; date of manufacture; batch number; batch expiration date; all directions for use and such warning of precautions concerning the contents as may be required by Federal or State laws and regulations.
Mix adhesive in conformance with the manufacturer’s instructions. -3 HOT BITUMEN Mix the adhesive asphaltic material with the filler homogeneously.
Supply materials meeting Tables 1081- 2 or 1081- 3 and 1081- 4. TABLE 1081 -2 ADHESIVE PROPERTIES OF ASPHALTI C MATERIAL WITH FILLER Property Min. Max. Test Method Softening point,°F. 200 - ASTM D36 Penetration, 100 g, 5 sec., 77°F 10 18 ASTM D5 Flow, inch, as modified in Subarticle 1081 -3(B) - 0.2 ASTM D5329 Viscosity, 400°F, poises or ASTM D4402 as modified in Subarticle 1081 -3(B) 30 75 ASTM D2669 Flash Point, C.O.C.,°F. 550 - ASTM D92
TABLE 1081 -3 ASPHALT PROPERTIES OF ASPHALTIC MATERIAL WITHOUT FILLER Property Min. Max. Test Method Penetration, 100 g, 5 sec., 77°F 25 - ASTM D5 Viscosity, 275°F poises 12 100 ASTM D2171 Viscosity Ratio, 275°F - 2.2 See Subarticle -3(B)
TABLE 1081 -4 FILLER PROPERTIES Property Min. Max. Test Method Filler Content, % by Weight 65% 75% See Subarticle 1081 -3(B) Filler Fineness, % Passing No. 325 75% - ASTM C430 as modified in Subarticle 1081- 3(B) Filler Fineness, % Passing No. 200 95% - Filler Fineness, % Passing No. 100 100% -
Determine flow according to Section 6 of ASTM D5329 with the exception that the oven temperature shall be 158°F ± 2°F and sample preparation done according to Section 7.1 of ASTM D5.
Viscosity is to be determined according to ASTM D2669 or ASTM D4402 using a spindle speed of 10 rpm. Heat the adhesive to approximately 410°F and allowed to cool. Determine viscosity at 400° F ± 1°F.
Properties of the base asphalt are to be determined on the material obtained from the following extraction and Abson recovery methods. Extract the asphalt by heating the adhesive just to the point where it will easily flow and then transfer 125 to 150 g into 400 ml of trichloroethylene with a temperature of 125°F to 150°F. Thoroughly stir this mixture to dissolve the asphalt. Decant the trichloroethylene -asphalt mixture decanted and the asphalt recovered using the Abson recovery method, ASTM D1856 as modified by the following. The extraction methods of ASTM D2172 do not apply and there will be no filtration of the solvent asphalt mixture. The extraction solution of trichloroethylene and asphalt shall be centrifuged for at least 30 minutes at 770 times gravity in a batch centrifuge. Decant this solution in the distillation flask, taking care not to include any filler sediment. Apply heat and bubble carbon di oxide solution slowly to bring the solution temperature to 300°F. At this point the carbon dioxide flow is increased to 800 ml to 900 ml per minute. The solution temperature is maintained at 320°F to 335°F with this carbon dioxide flow for at least 20 mi nutes and until the trichloroethylene vapors have been completely removed from the distillation flask. Repeat the above extraction- recovery method as necessary to obtain the desired quantity of asphalt. Use the asphalt recovered to determine penetration, 275°F viscosity, and 275°F viscosity ratio.
Determine the 275°F viscosity ratio by comparing the 275°F viscosity on the base asphalt before and after the thin- film oven test. Perform the thin -film oven test in accordance with ASTM D1754. Determine the specific gravity by pycnometer as in ASTM D70 for use in the thin -film oven test. Calculate the 275°F viscosity ratio by dividing the viscosity after the thin- film oven test by the original 275°F viscosity.
Separate the filler material from the asphalt to determine Filler Content and Filler Fineness. Determine the portion by weight of the adhesive insoluble in 1,1,1 trichloroethane by weighing 10.00 ± 0.01 grams of solid adhesive into a centrifuge flask with approximately 100 ml volume such as that specified in ASTM D1796. Add 50 ml of 1,1,1- trichloroethane to the adhesive, which should be broken up in small pieces to speed up the dissolution solids. Place the sample flask in a balanced centrifuge and spin using a minimum re lative centrifugal force of 150 in accordance with ASTM D1796 for 10 minutes. Remove the sample flask and decant the solid, taking care not to lose any solids. Repeat the application of solvent and centrifuging until the solvent becomes clear and the fil ler is visually free of asphalt. Dry the filler at 160° F ± 5°F to remove solvent and weigh the resulting filler. Filtration of the decanted solvent may be performed to verify there is no loss of filler. Percent filler content is calculated as follows: Filter Content, % by Weight = Filler Weight, grams x 100 Original Adhesive Weight, grams
Determine Filler Fineness according to ASTM C430 using number 325, 200 and 100 sieves. This method is to be modified by using a water soluble non -ionic wetting agent, such as Triton X -100, to aid the wetting action. Concentration of the surfactant solution shall be approximately 1% by weight. Thoroughly wet the one -gram dry sample in the surfactant solution and allowed to soak for 30 minutes. Transfer the filler completely into the sieve cup and apply water spray for 2 minutes. Surfactant solution may be added as needed and physical means used to disperse any clumped particles. Dry the sample and handle as described in ASTM C430.
Interested parties shall submit a sample to a qualified independent testing laboratory for testing in accordance with Subarticle 1081- 3(A) at no cost to the Department. Submit a Type 2 materials certification in accordance with Article 106 -3 with the resu lts and the name of the testing laboratory along with a qualification sample(s) of the same lot to the Department for evaluation.
Pack the adhesive in self -releasing cardboard containers which will stack properly. Containers shall h ave a net weight of 50 lbs. to 60 lbs. and contain two to four subcompartments. Ensure the label shows the manufacturer, quantity and batch number. Print “Bituminous Adhesive for Pavement Markers” or similar wording on the label.
A certification from the manufacturer showing the physical properties of the bituminous adhesive and conformance with the s pecifications shall be required before use.
Apply the adhesive according to the manufacturer’s requirements and the following requirements. Apply the adhesive when the road surface, ambient air and pavement marker temperatures are in the range of 50°F to 160°F on dry pavement. The composition of the adhesive shall be such that its properties will not deteriorat e when heated to and applied at temperatures up to 425°F using either air or oil -jacketed melters. Melt and heat the bituminous adhesive in either thermostatically controlled double boiler type units using heat transfer oil or thermostatically controlled e lectric heating pots. Do not use direct flame units. Heat the adhesive to between 375°F and 425°F and applied directly to the pavement surface from the melter/applicator by either pumping or pouring. Maintain the application temperature between 375°F and 425°F as lower temperatures may result in decreased adhesion while higher temperatures may damage the adhesive. Use sufficient adhesive to e nsure total contact with the entire bottom of the pavement marker. Apply pavement markers to the adhesive immediat ely (within 5 seconds) to assure bonding. Place the pavement marker in position by applying downward pressure until the marker is firmly seated with the required adhesive thickness and squeeze -out. Remove excessive adhesive squeeze- out from the pavement and immediately remove adhesive on the exposed surfaces of pavement markers. Soft rags with mineral spirits or kerosene may be used if necessary, to remove adhesive from exposed faces of pavement markers. No other solvent may be used. Do not waste or spi ll any excess adhesive on Department right of way. Remove and properly dispose of any adhesive spilled or dumped at such location. The Contractor, at no cost to the Department, shall correct any damage incurred to the Department, highway or appurtenances as a result of misplaced adhesive.