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    SECTION 02930

    SPRAYABLE COATING FOR MANHOLES

   PART 1 - GENERAL

   1.1 SECTION INCLUDES

    A. Surface preparation and installation of spray applied elastomeric solventless polyurethane coatings for concrete surfaces of proposed manhole structures at the locations indicated on the Contract Drawings.

    B. The solventless elastomeric polyurethane protective coating shall be installed on the interior surfaces of all concrete manhole structures including floor, sidewall and roof.

   1.2 QUALITY ASSURANCE

    A. Applicator: The applicator shall submit a satisfactory experience record including applications of the specified lining materials to concrete structures of similar design and complexity. The applicator and the applicator's spray equipment shall be approved by the material manufacturer.

    B. Manufacturer: Prior to the start of any work, the material manufacturer shall provide job-specific written recommendations for the surface preparation, installation and inspection of the lining system. The manufacturer shall also provide any assistance required by the Applicator, or the inspector, in the interpretation of their written recommendations.

   1.3 PERFORMANCE AND DESIGN REQUIREMENTS

    A. The lining shall provide protection from the following service conditions:

    Chemical Solutions Concentrations

    Sulfuric acid 20 percent *

    Sodium hydroxide 5 percent

    Ammonium hydroxide 5 percent

    Nitric acid 1 percent *

    Ferric acid 1 percent

    Soap 0.1 percent

    Detergent (linear alkylbenxyl sulfonate) 0.1 percent

    Bacterlologloal (BOD) > 700 ppm

    * Volumetric percentages of concentrated C.P. grade reagents

   1.4 SURFACE PREPARATION

    A. Concrete: Portland cement concrete shall be at least 28 days old before lining is applied.

    B. If necessary, surfaces shall be cleaned by high-pressure water blasting or steam cleaning resulting in a surface free from dirt, dust, sand, mud, oil, grease, and other objectionable substances prior to abrasive blasting. If detergents are used, they shall be completely washed off with plenty of fresh water.

    C. The surface shall be dry abrasive blast cleaned by way of light "brush blast", resulting in a sound surface, with no evidence of laitance, loose concrete, contaminants or debris, and shall display a definite anchor pattern or surface profile, resembling sandpaper, suitable for coating.

    D. After abrasive blasting, cavities or bugholes in concrete shall be either resurfaced with non-shrink, high-strength quick-set cementitious grout or solventless epoxy putty prior to priming. All cementitious resurfacing materials shall be abrasive blasted again before application of the primer, to provide a suitable anchor pattern. Solventless epoxy putties shall be brush finished but no further abrasive blasting shall be necessary prior to application of the primer. Consult the manufacturer for recommendations.

    E. The applicator shall have the option of using an imbedded fiberglass reinforcing screen to bridge cavities or bugholes on flat, vertical surfaces, thereby replacing the application of cementitious or epoxy resurfacing compounds wherever possible. Consult the manufacturer for detailed recommendations.

    F. Concrete surfaces may be damp before priming but shall be free of active leaks and standing water. All leaks shall be repaired in accordance with Engineer's instructions. Any other surface preparation recommended by the manufacturer shall be brought to the Engineer's attention and may be incorporated into the work, if acceptable to the Engineer. Consult the manufacturer for further recommendations if necessary.

    G. Final Cleaning: After all surface preparation is completed, surfaces adjacent to the work area shall be cleaned of dirt, blasting residues and other debris to prevent wind-blown contamination of the prepared substrate or freshly applied lining material. Just prior to primer application, all surfaces to be lined shall be thoroughly vacuumed or blown-off with oil-free, dry compressed air to remove all dust and blasting residues. All areas not to be lined, and which are located immediately adjacent to proposed leading edges, shall be taped off and protected.

   PART 2 - MATERIALS

   2.1 POLYURETHANE TOPCOAT

    A. The topcoat shall be Polibrid 705, as manufactured by Polibrid Coatings, Inc. of Brownsville, Texas, or approved equal. It shall be an ASTM Type V chemical cure, two component, 100% solids, elastomeric, aromatic polyurethane with no sand or asphaltic extenders added. It shall be capable of being sprayed at the specified thickness in a single application. It shall be a monolithic, flexible membrane with a Shore "D" hardness of 65 to 70 at 78oF; a tensile strength of 3000 psi and an elongation of 65% per ASTM D-638-77a; shall be resistant to abrasion as measured by a weight loss of no more than 60 mgs per ASTM D-4060; and shall have a water vapor transmission rate (WVTR) no greater than 0.045 grams/100 in2/24 hrs (75 mils DFT @ 73oF and 100% RH, ASTM F 1249-90).

   2.2 EPOXY PRIMER

    A. The primer shall be Polibrid 670, a moisture insensitive, 80% solids, modified amineadduct epoxy, as manufactured by Polibrid Coatings, Inc. of Brownsville, Texas, or approved equal. It shall be capable of being applied to moist or damp concrete surfaces.

   2.3 MIXING OF THE MATERIALS

    A. Polyurethane Topcoat: The base component (Side "A") of the topcoat shall be mixed with an agitator for at least 30 minutes before using. The catalyst (Side "B") does not require agitation. Prevent contamination by dust and moisture. The applicator shall use plural-component, high-pressure, airless spray equipment specially designed to simultaneously proportion the two components in a 2A:1B volume ratio; mix the components in-line; and spray the material through an airless spray gun.

    B. Epoxy Primer: Both primer components (Sides "A" and "B") shall be power agitated in their separate containers for at least 10 minutes, or until the entire contents are in complete suspension, before blending together. Both primer components shall be measured to their proper volume ratio, then poured into a clean separate container and mixed again by agitating for at least 5 minutes. Mixed primer materials that exceed their usable pot life shall be discarded.

   PART 3 - EXECUTION

   3.1 APPLICATION OF THE MATERIALS

    A. Sealer: Prior to resurfacing, if any, abrasive cleaned concrete surfaces shall be thoroughly saturated with fresh water, then treated with the specified silicate based penetrating sealer. The sealer shall be airless spray applied, undiluted, onto the pre-saturated concrete surfaces in a uniform, flood-coat at a rate of 150 sq.ft. per gallon. If shall be applied by means of a two-coat, wet-on-wet, cross hatched application. Any excess puddling of the waterproofing sealer shall be squeegeed or broomed out. Multiple applications may be necessary. Follow manufacturer's recommendations.

    B. Resurfacing Materials: Resurfacing shall provide a relatively flat surface with a "brushed" texture. Avoid excessive feathering onto surrounding areas. Follow manufacturer's recommendations.

    C. Epoxy Primer: The epoxy primer shall be spray applied to concrete surfaces at a film thickness of 5 mils DFT in a single coat using conventional high-pressure airless spray equipment. At 72oF, the recoat window, before application of the topcoat, shall be between 6 and 48 hours after primer application. At 90oF, the recoat window shall be between 2 and 24 hours after primer application. Consult the manufacturer for recommendations.

    D. Polyurethane Topcoat: The polyurethane topcoat shall be spray applied at a nominal film thickness of 75 mils DFT to all new concrete surfaces. The full topcoat thickness shall be sprayed in one application which may consist of several increments, all applied within the same day to a specific area. High profile areas shall be coated by means of 4-way passes to ensure that all surfaces receive the minimum specified coverage.

    E. Rigging and/or scaffolding, if required, shall be set up to permit ease of operation of the spray equipment and application of the coating materials and shall provide safe and clear access to all surfaces to be coated. The optimum distance from the tip of the spray gun to the surface to be coated is 24-inches.

   3.2 LEADING EDGES

    A. During surface preparation of concrete surfaces, a saw-cut shall be made along the entire proposed leading edge of the lining system. The saw-cut shall be at least 1/4" deep x 1/8" to 1/4" wide. Any sharp edges shall be rounded or trimmed off by sandblasting, chipping, wire brushing or any other method. The saw-cut shall be dried and vacuum cleaned of all dust and residue prior to priming. Areas not to be lined, but which are immediately adjacent to a leading edge, shall be taped off and protected from primer and topcoat overspray.

    B. The epoxy primer shall be applied onto saw-cut areas during normal primer application operations. When primer is ready to be topcoated, a liberal amount of the topcoat material shall be sprayed onto the saw-cut area, pressed by hand with a putty knife into the saw-cut cavity and then smoothed level, mechanically anchoring the lining system's leading edge to the concrete surface. After the top coat has set up, protective tape shall be razor cut, leaving a straight leading edge.

   3.3 TREATMENT OF EXPANSION JOINTS

    A. On concrete structures with expansion joints, a bond-breaking adhesive tape shall be centered and applied directly over the joint to be coated, after primer application. The tape may be PVC or polyethylene-backed adhesive tape and shall be of sufficient width so as to completely bridge the expansion joint and extend a minimum of 1" on either side of the joint. The bond-breaking adhesive tape, already placed over the expansion joint, shall then be topcoated at the specified film thickness, concurrently with normal spray application on adjacent surfaces.

   3.4 FIELD QUALITY CONTROL

    A. Each coat shall be applied in a manner that will produce a pinhole-free membrane which resembles the topography of the underlying substrate. A log of materials consumption shall be kept throughout the job and shall record the volumes of materials applied. When spraying the polyurethane topcoat, the applicator shall use a machine-mounted stroke counter to control the volume of materials applied to pre-measured areas.

    B. The colors of the primer and the topcoat shall provide a contrast to assist in obtaining complete coverage. The epoxy primer shall be turquoise-blue in color. The polyurethane topcoat shall be light tan or beige in color. Surfaces showing blisters or other visible defects will not be accepted and shall be entirely removed or repaired per manufacturer's recommendations.

    C. Lined surfaces shall be cleaned to permit visual inspection and spark testing. A minimum 12 hours after application, the lining shall be spark tested with high-voltage holiday detection equipment set at a minimum of 100 volts per mil of total lining thickness. all pinholes detected visually or by spark testing shall be clearly marked and then repaired in accordance with the manufacturer's recommendations. At the opinion of the Engineer, areas with excessive pinholes shall be re-sprayed rather than patched individually by hand.

   3.5 WEATHER CONDITIONS

    A. Epoxy primer shall be applied when surface temperatures are above 60oF. Topcoat materials shall be applied when ambient temperatures are between 40oF and 120oF. Lining materials shall only be applied if the relative humidity is 95% or lower, and substrate temperature is at least 5oF above due point. Lining operations shall cease when raining, foggy or when rain is imminent.

   3.6 PROTECTION

    A. During surface preparation, any nearby installations, equipment, vehicles, structures, etc. shall be protected from blasting grit and dust. During lining application, such installations shall be protected from oversprayed, dropped or spilled materials. All surfaces so damaged shall be cleaned, repaired, replaced or painted as acceptable to the Engineer.

   3.7 DELIVERY, STORAGE, AND HANDLING

    A. Lining materials shall be delivered to the job in their original unopened containers with labels intact, shall be stored indoors over wood pallets in cool and dry conditions, and shall be protected against excessive moisture, heat or freezing. No adulterant, unauthorized thinner, or other material not included in the formulation shall be added to the materials for any purposes.

   3.8 MEASUREMENT AND PAYMENT

    A. Work and materials covered under this section shall not be paid for directly, but shall be considered subsidiary to the various bid items required to complete the project.

    END OF SECTION 02930

Rembco Geotechnical Contractors specializes in slope stabilization, foundation repair and support, shoring, grouting, soil nails, micropile installations, and sinkholes. We are experienced in these applications: micro piles, sinkhole repair, permeation grouting, pressure grouting, soil nails, chemical grouting, micropiles, compaction grout, rock anchors and compaction piles. Our specialties are rock anchor, chemical and compaction grouting, mini piles, sinkhole repair, micropiles, and soil nailing. We use a problem-solving approach in the geotechnical portions of buildings, bridges, water plants, sewage plants, tunnels, sinkholes, caisson, and roads. Rembco techniques apply when adding new real estate structures: especially rock anchor, microfine grouting, soil nailing, micropile installations for foundation support. Add URL Construction, Drilling and Concrete