SPECIFICATIONS REFERENCE
1.0 CONTRACTOR REQUIREMENTS – GENERAL
1.1 Pursuant to section 34-8-1(a) of the Code of Alabama, each contractor must submit with their bid, proof of licensing through the Alabama State Board of Licensing for General contractors, with approved maximum bid limits sufficient to cover the bid related to this specification. Failure to comply will be cause for rejection of the bid. A copy of the vendor’s current year’s license will expedite the valuation process.
1.2 Each contractor should submit with their bid, proof of liability insurance in the minimum amount of $500,000 per occurrence, $1,000,000 aggregate. Each contractor should further provide proof of workman’s compensation insurance sufficient to satisfy all legal requirements of the State of Alabama. Failure to provide this documentation with the bid package will delay the evaluation process.
1.3 The successful bidder will be required to submit a performance bond, in the amount of one and one-half times the bid price of $300,000.00, whichever is greater, prior to award of the purchase order.
1.4 All documentation MUST be submitted prior to award of the purchase order. All insurance certificates and bond instrument shall indicate State of Alabama, Department of Finance, and Division of Purchasing as certificate/bond holder.
1.5 Due to the nature of this project, award will be made on an “All or None” basis to the recommended vendor, who during the course of our bid evaluation is found to be the lowest possible responsible. Award will be made by added together all unit items costs for a total bid.
1.6 After the award of the contract and before materials are delivered to the job site, the contractor shall submit to the Division Maintenance Engineer a complete list of all materials proposed to be furnished and installed.
1.7 In addition, the contractor shall submit satisfactory written certification of compliance with the ASTM standards contained within this specification.
1.8 Vendors are hereby notified that this contract may be subject to the Alabama Gross Receipts Tax.
2.0 WORK SCOPE
2.1 All work shall be done in compliance with applicable sections of the Alabama Department of Transportation Standard Specifications for Highway Construction, 2008 Edition, Alabama Department of Transportation Standard Drawings, and the latest edition of the MUTCD. The materials used shall be chosen from the Materials, sources, and Devices with Special Acceptance Requirements Manual. The traffic control scheme shall be submitted to the Division Traffic Engineer for his/her review seven (7) days prior to starting initial work.
2.2 The quantity stated in this solicitation is an estimate only for comparative purposes and in no way obligates the Department to any specific quantity of purchase. Actual maintenance requirements may be less than or greater than the estimated quantity as shown for each item. All quantities and dimensions are estimated and should be field verified by the contractor.
2.3 The contractor will be responsible for all traffic measures. Attention is drawn to the fact that this work will be performed under traffic conditions. The contractor will be responsible for assuring that all traffic control devices meeting the Manual for Uniform Traffic Control Devices and that they are placed on the roadway in compliance with part 6 of the same manual. The contractor will be responsible for insuring that all employees wear appropriate safety apparel in accordance with the latest edition of the MUTCD and in accordance with the standards of the ANSI 107-1999 Class 2.
2.4 All repairs should cause minimal loss in flow capacity and should increase the strength of the structure to maintain proper horizontal and vertical profiles of the roadway above.
2.5 Effective period will be from fifteen (15) calendar days from the date of the Notice to Proceed through completion of the work.
2.6 The contractor will begin work fifteen (15) working days from the date of the Notice to Proceed and will have 90 calendar days to complete the work.
3.0 PERFORMACE REQUIREMENTS
3.1 Bid price shall include all materials, hardware, supplies, tools, equipment, labor, transportation, and other necessary incidentals required for the completion of the work in an approved and satisfactory manner.
3.2 If required, on-site storage of job materials and/or equipment is to be coordinated with the District Manager prior to the beginning of work. The security of any material and/or equipment left on-site will be the responsibility of the contractor.
3.3 The performance of any work under these specifications will not be deemed complete until the contractor has satisfactorily removed all debris and cleaned up the work site. At no time during the performance of work will materials, debris or trash be allowed to accumulate in such a manner as to endanger the safe performance of the work of the safety of the traveling public.
3.4 This work will be performed upon completion at designated location.
3.5 Unit of work for debris removal will be included in the lining unit price and shall include the removal and disposal of all damaged and removed material. All material which is to be removed shall be disposed of the contractor and these related costs should be reflected in the unit price. Work will include removal of various types of debris affecting the designed flow of the drainage structure. The contractor shall be required to handle all disposal of debris removal.
3.6 No work will be performed without prior approval and notification by the Division Maintenance Engineer.
3.7 Note that the roadway pipe will be constructed of concrete.
3.8 Unit work required at each site is to be approved by on-site inspector or Division Maintenance Engineer prior to work at each site.
3.9 The contractor will be required to remove any trees to allow for repairs to the headwall.
3.10 The Contractor shall perform construction so as not to adversely impact the local environment in violation of regulations enforced by the Alabama Department of Environmental Management (ADEM) or the Environmental Protection Agency (EPA). If the Contractor is found to be in violations, the work will be stopped until conditions are restored to a satisfactory state.
3.11 The Contractor shall warrant all work against defects in materials and workmanship for a period of two (2) years to ensure maximum performance of the lining. Warranty inspection will be performed two (2) years from the date of acceptance at the Contractor’s expense by video inspection. Any defects will be corrected at the Contractor’s expense.
4.0 MINIMUM SPECIFICATIONS
4.1 Installation Crew
4.1.1 Foreman shall have experience including as an operator/applicator of the equipment/product required to meet the proposal. Provide manufacturer certification that the Foreman has been trained and approved in the handling, mixing, and application of the products to be used.
4.1.2 Operators/applicators shall have experience in proposed construction within storm drainage systems and shall have successfully demonstrated all the duties for which he/she shall be responsible on this project. Provide four (4) references which demonstrate previous successful projects completed for the specified structural protective coating system or comparable during the last (2) years.
4.1.3 Operator/applicators responsibilities include but are not limited to the following:
a. Ensure that all surfaces to be lined are clean and free of laitance and loose material, using air and water to blast debris from pipes/culverts/bridges.
b. Regulate material content so as to provide a proper mix that will be plastic enough to give good compaction and low percentage of rebound without sagging.
c. A procedure should be followed so that corners are filled with material to eliminate voids as much as possible in the lining and to prevent loss of drainage flow.
d. Determined necessary operating procedures for placement of the lining material in confined areas, over extended distances and/or around unusual obstructions where placement methods may need to be adjusted to provide adequate structural function.
e. Crews should be directed when to start and stop if material placement is not in conformance to the placement guidelines.
f. Ensure that any pockets of structurally unsound material are removed and replaced.
g. The lining should be constructed neatly and in a workmanlike manner.
h. Crews shall have successfully demonstrated all of the duties for which they shall be responsible on this project as specified by the product’s required construction procedures.
4.2 Equipment Certification
4.2.1 Certification that the equipment to be used for applying the products has been manufactured or approved by the protective coating manufacturer and Application personnel have been trained and certified for the proper use of the equipment. Certification letter shall be dated within six months of the bid date.
4.2.2 Equipment shall be used that is capable of installation at a rate that will provide adequate production and with an accuracy that will ensure uniformity. Weighing equipment shall be capable of batching with the accuracy specified in ASTM C-94. Volumetric equipment shall be capable of batching with the accuracy specified ASTM C-685.
4.3 TESTING AGENCY QUALIFICATIONS
4.3.1 Contractor shall secure, at his expense, the services of a testing laboratory meeting the requirements of ASTM E-329. The testing laboratory shall be normally engaged in the testing of concrete materials and concrete. Contractor shall submit the qualifications of the testing agency to owner for approval in accordance with the requirements for submittals contained in the specification. The materials testing laboratory shall make all tests to provide the quality control that shows that the shotcrete and shotcrete materials provided meet or exceed the requirements of this specification. As interpretations of the test results is required, contractor shall further be responsible for securing the services of an independent Professional Engineer licensed in the State of Alabama who shall review and certify the test results. Certified test results shall be submitted by contractor to owner in triplicate.
4.4 STRUCTURAL DESIGN PARAMETERS
4.4.1 Structure condition should be considered a partially deteriorated gravity culvert.
4.4.2 Soil type should be considered saturated for maximum performance of the product.
4.4.3 Design thickness should be based on design requirements found in the design standards listed for each product/process throughout this document.
4.4.4 Ovality of the pipe shall not be greater than 10%.
4.4.5 The soil load used for design shall be 120 pounds per cubic foot.
4.4.6 The Traffic Load will be AASHTO HS-20-44 Highway.
4.4.7 Soil Modulus shall be 1000 psi
4.4.8 The Factor of Safety shall be 2.0.
4.4.9 The soil cover shall be measured at the distance from the grade to the crown of the pipe.
4.4.10 The water table shall be considered saturated condition (same elevation as the soil cover at the top of any pipe).
4.4.11 The design life shall be a minimum of 50 years.
4.4.12 All designs must be submitted with calculations prior to performing the work. Calculations should be clear and should reference applicable American Society for Testing and Materials (ASTM), American Concrete Institute (ACI), National Association of Corrosion Engineers (NACE), and the Society for Protective Coatings (SSPC) standards.
4.4.13 Design calculations shall include Flexural Strength and Flexural Modulus capable of meeting all the load requirements based on the aforementioned design parameters.
4.4.14 Third party testing shall be used to confirm Flexural Strength used on this project.
4.4.15 Third party testing shall be used to confirm long term Flexural Modulus of Elasticity. This third party testing will verify the long term reduction factor (Creep Analysis) of a minimum of 50%. This long term reduction factor verification shall be conducted utilizing ASTM D2990-01 via a third party independently certified laboratory.
4.5 APPROVED LININGS
4.5.1 To be designed and recommended by the bidder and certified to meet all design parameters in Section 4.4
4.5.2 All linings must be preceded by construction that grouts voids in the concrete culvert and rock walls and floor.
4.5.3 After grouting is complete, install # 4 reinforcing steel bars at 8” centers, 24” long and 2 #4 reinforcing steel bars longitudinally at the invert for the entire length of the concrete and rock culverts. Reinforcing steel shall meet the requirements of ASTM A-615, Grade 60.
5.0 PRODUCTS
5.1 Must meet all applicable standards (ASTM, ACI, NACE, etc) as provided in the bid package.
5.2 Any testing required by the provided standards will be required by a third party as previously stated prior to payment.
6.0 DELIVERY, STORAGE AND HANDLING OF MATERIALS
6.1 Contractor shall be solely responsible for the proper delivery, storage, and handling of materials to prevent contamination, segregation, extreme temperature, exposure or damage as prohibited by the manufacturer, deformation of the product that reduces the strength and durability of the material.
6.2 Damaged or unsuitable products shall be promptly removed from the job site and shall be replaced with suitable materials.
7.0 EXECUTION
7.1 Flow Control
7.1.1 Contractor shall provide for maintenance a flow in the affected portions of the drainage system during the installation of the shotcrete lining.
7.2 Cleaning
7.2.1 Prior to the installation of shotcrete lining, contractor shall thoroughly clean the pipe/culvert designated to receive the liner. Cleaning shall constitute removal of all solids, roots, deposits, and other matter which would preclude the installation of the concrete liner into the pipe line.
7.3 Inspection of Pipelines
7.3.1 Prior to the installation of shotcrete lining, contractor shall inspect the pipe/culvert designated to be lined.
7.4 Surface Preparation
7.4.1 Contractor shall remove all unsound and loose material before applying shotcrete. Contractor shall chip or scarify any area to be repaired to remove offsets which would cause an abrupt change in thickness without suitable reinforcement. All edges shall be tapered so as to leave no square shoulders at the perimeter of the cavity. After all chipping work has been completed; the entire surface shall be thoroughly sandblasted and cleaned with a compressed air blast and jet water blast using a cement gun to remove all dirt, debris and loose particles to permit a satisfactory bond between the existing surface and the shotcrete. Air pressure in the cement gun shall be less than 50psi.
7.4.2 Contractor shall sandblast existing surfaces that do not require chipping to remove paint, oil, grease, silt, slime, and other contaminants, and provide a roughened surface for proper bonding of the shotcrete. Blasting of steel surfaces shall be in compliance with SSPC-SP6.
7.4.3 The chipped and blasted surfaces shall be dampened but without visible running water. Shotcrete shall not be placed on any area where free running water exists.
7.4.4 Loose bricks, in areas are not specifically mentioned, shall be removed and the void filled with shotcrete. This shall apply only to isolated situations where only a few (one to ten) are loose.
7.4.5 Void areas that extend beyond the outside plane of the pipe line or manhole/junction box into the surrounding soil shall be filled and stabilized using pressure injected grout to the outside plane of the pipe line.
7.4.6 Contractor shall fill all voids and repair deficiencies in the culvert and manhole/junction box with shotcrete.
7.4.7 Contractor shall repair any damage to the existing structure resulting from his cleaning or void filling operations at no cost to the owner.
7.4.8 Contractor shall remove and properly dispose of, as approved by the Engineer, all debris and rebound from the pipe/culvert that results from his cleaning and shotcrete placement operations. No debris shall be permitted to wash down into the drainage system.
7.4.9 The contractor shall contact utilities to identify all pipe and conduit in the pipe/culvert to be rehabilitated.
7.5 Placement of Lining
7.5.1 Linings shall be placed in such a manner as to meet or improve current flow.
7.5.2 Linings shall be placed as directed by the provided design standards (ASTM, ACI, SSPC, NACE, etc) and meet the minimum parameters as verified by the engineer of record. 6.5.3
7.8 Surface Finish
7.8.1 Contractor shall bring the lining material to an even plane and well formed corners where applicable.
7.8.2 After the body coat has been placed, the surface shall be trued to remove high areas and expose low areas. Low areas must be filled to ensure a true, flat surface.
7.8.3 After the surface has been trued, the entire surface shall receive a treatment providing a smooth finish surface with any brush finish (if concrete) to be finished parallel to the flow.
7.9 Lateral Reinforcement or Abandonment
7.9.1 Contractor is responsible for identifying all active and abandoned laterals and their locations. The contractor shall submit a lateral abandonment plan prior to the beginning of work. The plan shall include the locations and sizes of all laterals and whether they are active or abandoned.
7.9.2 It shall be the contractor’s responsibility to determine and to assure that all live laterals are connected. Laterals reinstatement shall be completed from inside the pipe. Excavation for lateral reinstatement shall be permitted.
7.10 Index of Specifications
7.10.1 Null-Provided with bid package
8.0 PAYMENT
8.1 All incidental cost should be included in the unit prices. The attachment to these specifications will be used as a guide in price calculation.
8.1.1 Unit price is per “EACH” structure.
8.1.2 Bid will be awarded based on the lowest bid that meets all design parameters in Section 4.4.
8.2 Any bypass pumping, cleaning, pre and post construction televising, labor, equipment, materials, traffic control, installation, service reconnection/abandonment, safety, dust/erosion control, testing, site restoration and all other work specified or not, which is reasonably required to provide a completed installation shall be included in the bid prices as incidental.
8.3 Before payment is made, all test results must be submitted and confirmed that the lining meets all the aforementioned specifications.
8.4 Invoice must indicate the unit of work performed per location and shall be an invoice including the name and address on the purchase order/contract. Invoice to be submitted and processed after final acceptance of work performed.
8.5 Payment will be made after all structures are complete.
1.0 CONTRACT REQUIREMENTS – PIPING/CULVERTS
1.1 Pursuant to section 34-8-1(a) of the Code of Alabama, each contractor must submit with their bid, proof of licensing through the Alabama State Board of Licensing for General contractors, with approved maximum bid limits sufficient to cover the bid related to this specification. Failure to comply will be cause for rejection of the bid. A copy of the vendor’s current year’s license will expedite the valuation process.
1.2 Each contractor should submit with their bid, proof of liability insurance in the minimum amount of $500,000 per occurrence, $1,000,000 aggregate. Each contractor should further provide proof of workman’s compensation insurance sufficient to satisfy all legal requirements of the State of Alabama. Failure to provide this documentation with the bid package will delay the evaluation process.
1.3 The successful bidder will be required to submit a performance bond, in the amount of the bid prior to award of the purchase order.
1.4 All documentation MUST be submitted prior to award of the purchase order. All insurance certificates and bond instrument shall indicate State of Alabama, Department of Finance, and Division of Purchasing as certificate/bond holder.
1.5 In accordance with section 41-16-59 of the Code of Alabama, the successful bidder in this solicitation is restrained from assigning or sub-contracting any portion of work under this contract.
1.6 Due to the nature of this project, award will be made on “All or None” basis by group.
1.7 Vendors are hereby notified that this contract may be subject to the Alabama Gross Receipts Tax.
1.8 After the award of the contract and before materials are delivered to the job site, the contractor shall submit to the Division Maintenance Engineer a complete list of all materials proposed to be furnished and installed.
1.9 In addition, the contractor shall submit satisfactory written certification of compliance with the ASTM standards contained within this specification.
2.0 WORK SCOPE
2.1 All work shall be done in compliance with applicable sections of the Alabama Department of Transportation Standard Specifications for Highway Construction, 2008 Edition, Alabama Department of Transportation Standard Drawings, and the latest edition of the MUTCD. The materials used shall be chosen from the Materials, sources, and Devices with Special Acceptance Requirements Manual. The traffic control scheme shall be submitted to the Division Traffic Engineer for his/her review seven (7) days prior to starting initial work.
2.2 The quantity stated in this solicitation is an estimate only for comparative purposes and in no way obligates the Department to any specific quantity of purchase. Actual maintenance requirements may be less than or greater than the estimated quantity as shown for each item. All quantities and dimensions are estimated and should be field verified by the contractor.
2.3 The contractor will be responsible for all traffic measures. Attention is drawn to the fact that this work will be performed under traffic conditions. The contractor will be responsible for assuring that all traffic control devices meeting the Manual for Uniform Traffic Control Devices and that they are placed on the roadway in compliance with part 6 of the same manual. The contractor will be responsible for insuring that all employees wear appropriate safety apparel in accordance with the latest edition of the MUTCD and in accordance with the standards of the ANSI 107-1999 Class 2.
3.0 PERFORMACE REQUIREMENTS
3.1 Bid price shall include all materials, hardware, supplies, tools, equipment, labor, transportation, and other necessary incidentals required for the completion of the work in an approved and satisfactory manner.
3.2 If required, on-site storage of job materials and/or equipment is to be coordinated with the District Manager prior to the beginning of work. The security of any material and/or equipment left on-site will be the responsibility of the contractor.
3.3 The performance of any work under these specifications will not be deemed complete until the contractor has satisfactorily removed all debris and cleaned up the work site. At no time during the performance of work will materials, debris or trash be allowed to accumulate in such a manner as to endanger the safe performance of the work of the safety of the traveling public.
3.4 The work to consist of the lining of pipes using shotcrete material will require:
3.4.1 The Division Maintenance Engineer may request the lining of roadway pipes/culverts as needed within the Second Division. Not all pipes/culverts inspected will necessarily be lined. Note that roadway pipes may be constructed of but are not limited to PVC, corrugated plastic, corrugated metal, bituminous coated corrugated metal, terracotta or reinforced concrete.
MINIMUM SPECIFICATIONS – LINES 00020 THROUGH 00026
3.5 The work using cured in place pipe (CIPP) and grouted in place (GIPP) material is to consist of color video inspection of roadway edge drains and roadway pipes and the lining and will require:
3.5.1 Upon the Division Maintenance Engineer’s request, the contractor shall inspect by means of a video camera any roadway edge drains or roadway pipes within the Second Division on any State route. The Division Maintenance Engineer will have the pipes cleaned prior to the contractor’s arrival at the site. The contractor shall deliver a report detailing the condition of the pipes and a copy of the inspection on DVD or the latest media format to the Division Maintenance Engineer.
3.5.2 Upon review of the inspection video, the Division Maintenance Engineer may request the lining of edge drain laterals and roadway pipes as needed. Not all pipes inspected will necessarily be lined. Note that edge drain laterals and roadway pipes may be constructed of but are not limited to PVC, corrugated plastic, corrugated metal, bituminous coated corrugated metal, terracotta or reinforced concrete.
3.6 The method of lining the pipes shall be as follows:
3.6.1 For pipes from 4 to 30 inches in diameter, the cured in place (CIPP) liner shall be a continuously extruded, folded Polyvinyl Chloride (PVC) Fold-and-Form pipe liner and the blow-molding or thermoforming of the pipe liner shall fold the liner in to the shape of the existing pipe. The liner shall “Ultraliner” or equivalent product.
3.6.2 For pipes from 36 to 55 inches in diameter, the grouted in place pipe (GIPP) line shall be a High
Density Polyethylene (HDPE) sheeting with studs or other texturing to provide a consistent void between the sheeting and the inside wall of the existing pipe. The sheeting shall be made continuous by an overlap welding process. The lining shall be adhered to the walls of the existing pipe by injecting epoxy grout in to the voids formed by the studs on the sheets. The liner shall be a “Trolining” or equivalent product.
3.6.3 Upon completion of the installation, the liners shall:
3.6.3.1 Extend continuously from the inlet to the outlet of each pipe section. The inlet or outlet can be a manhole, junction box, grated inlet, headwall or projection pipe.
3.6.3.2 Provide a tightly conforming fit against the inner wall of the host pipe.
3.6.3.3 Provide for complete structural integrity independent of the load carrying capacity of the host pipe.
4.0 MINIMUM SPECIFICATION – lines 00001 THROUGH 00018
4.1 Foreman shall have a minimum of four years of experience including four years as a shotcrete nozzle operator.
4.2 Nozzle operator shall have a minimum of four years experience in shotcrete construction within storm drainage systems and shall have successfully demonstrated all of the duties for which he/she shall be responsible on this project including, but not limited to the following:
4.2.1 Ensure that all surfaces to be shot are clean and free of laitance and loose material, using air and water to blast from the nozzle as required.
4.2.2 Regulate water content so as to provide a mix that will be plastic enough to give good compaction and a low percentage of rebound without sagging.
4.2.3 The nozzle should be held at a proper distance and as nearly normal to the surface as the workspace permits to secure maximum compaction with minimum rebound.
4.2.4 A sequence routine should be followed so that corners are filled with sound shotcrete and encased reinforcement without placing porous material behind the reinforcing.
4.2.5 Determine necessary operating procedures for placement of shotcrete in confined areas, over extended distances and/or around unusual obstructions where placement velocities and mix consistencies may require adjustment.
4.2.6 Crews should be directed when to start and stop the flow of material and shall stop work if the material is not arriving uniformly at the nozzle.
4.2.7 Ensure sand and slough pockets are cut out for replacement.
4.2.8 The shotcrete should be finished in a neat and workmanlike manner.
4.2.9 Crews shall successfully demonstrate all of the duties of which they shall be responsible on this project including, but not limited to, maintaining proper pressure on the cement gun to ensuring the necessary nozzle velocity and ensuring that material fed to the nozzle is uniform.
4.3 Testing Agency Qualifications:
4.3.1 Contractor shall secure, at his expense, the services of a testing laboratory meeting the requirements of ASTM E-329. The testing laboratory shall be normally engaged in the testing of concrete materials and concrete. Contractor shall submit the qualifications of the testing agency to owner for approval in accordance with the requirements for submittals contained in the specification. The materials testing laboratory shall make all tests to provide the quality control that shows that the shotcrete and shotcrete materials provided meet or exceed the requirements of this specification. As interpretations of the test results is required, contractor shall further be responsible for securing the services of an independent Professional Engineer licensed in the State of Alabama who shall review and certify the test results. Certified test results shall be submitted by contractor to owner in triplicate.
5.0 PRODUCTS – LINES 00001 THROUGH 00018
5.1 Cement
5.1.1 Portland Cement conforming to ASTM C-150, Type 1, unless otherwise designated.
5.2 Aggregate
5.2.1 Aggregate shall be naturally siliceous sand conforming to the requirements of ASTM C-33, unless otherwise designated.
5.2.2 Aggregate shall contain less that 3% nor more than 6% moisture.
5.2.3 The combined gradation of coarse and fine aggregates shall conform to the following unless otherwise designated.
Sieve Size Percentage by Weight
(US Standard) Passing
Square Mesh Individual Sieve
1 inch —
3/4 inch —
1/2 inch 100
3/8 inch 95-100
No. 4 72-85
No. 8 52-73
No. 16 36-55
No. 30 20-38
No. 50 7-20
No. 100 2-12
No. 200 0-5
5.3 Water
5.3.1 Only fresh, potable water shall be used in mixing.
5.4 Admixtures
5.4.1 Admixtures shall be subject to the approval of the Engineer. Admixtures containing calcium chloride or tricthanolamine shall not be used. Admixtures used in combination shall be physically and chemically compatible and shall be so certified by the manufacturer. Admixtures shall be products of a single manufacturer who shall provide, as necessary, assistance and advice to Engineer on the proper use of admixtures at no increase in contract price.
5.4.1.1 Chemical admixtures shall conform to ASTM C-494.
5.4.1.2 Air entrained admixtures shall conform to ASTM C-260.
5.4.1.3 Fly ash and pozzolanic materials shall conform to ASTM C-618.
5.4.1.4 Accelerating admixtures shall develop quick set and high-early strength characteristics as follows:
Time of Initial Set 3 minutes maximum
8 Hour Compressive Strength 600 psi minimum
Time of setting shall be determined by contractor in accordance with ASTM C-266, except that the accelerator shall be added to 50 grams of cement, together with the water to produce a water to cement ratio of 0.40, in varying expected to be used to the actual shotcrete installation. The minimum possible time interval shall be used to attain the proper mixing without disturbing the initial set of the paste.
The compressive strength shall be determined by contractor in accordance with ASTM C-109, except that the accelerator in varying percentages expected to be used in the shotcrete mix design shall be added to the mortar prepared with water cement ratio of 0.40. In order to accomplish the molding of the specimen without disturbing the initial setting of the mortar, the intervals of time in the above specification are hereby waived.
5.5 Reinforcement
5.5.1 Steel Reinforcement
5.5.1.1 Reinforcing steel shall meet the requirements of ASTM A-615, Grade 60 unless otherwise designated.
5.5.1.2 Welded wire fabric or wire mesh shall conform to ASTM A-185. Unless otherwise specified, the wire mesh shall be 2 inches by 2 inches – 12/12 gauge galvanized welded wire fabric.
5.5.1.3 Metal accessories, including all spacers, ties, fasteners and other devices shall be provided for proper spacing, placing and supporting the reinforcement.
5.5.2 Fiber Reinforcement
5.5.2.1 Reinforcement shall be steel fibers or polypropylene fibrillated fibers conforming to the requirements of ASTM C-1116 for fiber-reinforced concrete and shotcrete. Unless otherwise designated by the Engineer, polypropylene or steel fiber shall be added to the shotcrete mix at a rate recommended by the manufacturer of fiber.
5.5.2.2 Unless otherwise specified by the Engineer, steel fibers shall be 0.016 inches in diameter, and between ½ and 1 ½ inches long in amounts up to 2 percent by volume of shotcrete; and collated polypropylene fibers in amounts greater than 0.1 percent by volume of fiber added.
5.6 Delivery, Storage and Handling of Materials
5.6.1 Contractor shall be solely responsible for the proper delivery, storage and handling of materials to prevent contamination, segregation or damage.
5.6.2 Cement shall be stored in weather tight enclosures to protect against moisture and contamination.
5.6.3 Aggregate shall be properly arranged and stockpiled to prevent contamination, evaporation, freezing and other damage.
5.6.4 Reinforcing steel and fibers shall be carefully bundled, tagged and stored above ground.
5.6.5 Damaged or unsuitable products shall be promptly removed from tehjob site and shall be replaced with suitable materials.
5.7 Structural Requirements
5.7.1 Shotcrete component materials shall be selected and proportioned so that as to produce a minimum 28-day compressive strength of 5000 psi and a minimum 38 day flexural strength of 800 psi.
5.7.2 Shotcrete shall be composed of Portland Cement, aggregate, water and fibers where specified, proportioned so as to produce a concrete suitable for pneumatic application and meeting the specified strength requirements herein set forth.
5.8 Equipment
5.8.1 Placing equipment shall consist of spray nozzle for ejection of dry material and water in an intimate mixture, separate hoses to deliver dry materials and water to the nozzle, a suitable machine to introduce the dry materials to the deliver hose under air pressure, and air and water systems. The water supply system shall consist of a local reservoir and a positive displacement pump capable of supply water through a regulating valve, easily and accurately controllable by a nozzle man, in sufficient amount and at a pressure slightly above the operating air pressure recommended by the manufacturer of the delivery machine.
5.8.2 The nozzle pressure shall be determined by the type of work involved and shall conform to the following:
50 to 70 lbs: For rough or heavy work
70-75 lbs: For high lifts or long hose to ensure against clogging
5.8.3 Maximum length of hose for the application of shotcrete shall be approximately 100 feet. Contractor may use as much as 500 feet of hose if the supply nozzle pressures are increased to maintain proper velocity upon approval from Engineer.
5.8.4 Air compressors shall have sufficient capacity to provide without interruption, the pressure and volume of air necessary for the longest hose delivery. Capacity determinations shall include allowance made for the air consumed in blowing rebound, cleaning, reinforcing and for incidental use.
5.8.5 Compressor equipment shall be of such capacity so as to ensure air pressure at the special mixer capable of producing the following material velocities:
375 to 500 feet per second using ¾ inch or 1 inch nozzle
425 to 550 feet per second using 1 ½ inch nozzle
5.8.6 Contractor shall maintain water pressure at approximately 20 pounds higher than the highest air pressure required for placing. The water pressure shall be uniformly steady (non-pulsating).
5.8.7 No air supply system shall be used that delivers air contaminated by oil, or that is incapable of maintaining constant pressure.
5.8.8 No hand-mixed materials shall be permitted.
5.8.9 When using fiber reinforcement, fibers shall be uniformly distributed throughout the mix. Batch proportioning and the use of screens shall be required. Continuous proportioning shall be permitted on if the feeder is carefully synchronized with the mixer to collate the fibers.
6.0 EXECUTION – LINES 00001 THROUGH 00018
6.1 Flow Control
6.1.1 Contractor shall provide for maintenance a flow in the affected portions of the drainage system during the installation of the shotcrete lining.
6.2 Cleaning
6.2.1 Prior to the installation of shotcrete lining, contractor shall thoroughly clean the pipe/culvert designated to receive the liner. Cleaning shall constitute removal of all solids, roots, deposits, and other matter which would preclude the Installation of the concrete liner into the pipe line.
6.3 Inspection of Pipelines
6.3.1 Prior to the installation of shotcrete lining, contractor shall inspect the pipe/culvert designated to be lined.
6.4 Surface Preparation
6.4.1 Contractor shall remove all unsound and loose material before applying shotcrete. Contractor shall chip or scarify any area to be repaired to remove offsets which would cause an abrupt change in thickness without suitable reinforcement. All edges shall be tapered so as to leave no square shoulders at the perimeter of the cavity. After all chipping work has been completed; the entire surface shall be thoroughly sandblasted and cleaned with a compressed air blast and jet water blast using a cement gun to remove all dirt, debris and loose particles to permit a satisfactory bond between the existing surface and the shotcrete. Air pressure in the cement gun shall be less than 50psi.
6.4.2 Contractor shall sandblast existing surfaces that do not require chipping to remove paint, oil, grease, silt, slime, and other contaminants, and provide a roughened surface for proper bonding of the shotcrete. Blasting of steel surfaces shall be in compliance with SSPC-SP6.
6.4.3 The chipped and blasted surfaces shall be dampened but without visible running water. Shotcrete shall not be placed on any area where free running water exists.
6.4.4 Loose bricks, in areas are not specifically mentioned, shall be removed and the void filled with shotcrete. This shall apply only to isolated situations where only a few (one to ten) are loose.
6.4.5 Void areas that extend beyond the outside plane of the pipe line or manhole/junction box into the surrounding soil shall be filled and stabilized using pressure injected grout to the outside plane of the pipe line.
6.4.6 Contractor shall fill all voids in the pipe line and manhole/junction box with shotcrete.
6.4.7 Contractor shall repair any damage to the existing structure resulting from his cleaning or void filling operations at no cost to the owner.
6.4.8 Contractor shall remove and properly dispose of, as approved by the Engineer, all debris and rebound from the pipe/culvert that results from his cleaning and shotcrete placement operations. No debris shall be permitted to wash down into the drainage system.
6.4.9 The contractor shall contact utilities to identify all pipe and conduit in the pipe/culvert to be rehabilitated.
6.5 Batching and Mixing
6.5.1 The moisture content of the combined aggregate at the time of mixing with cement shall be in the range of 3% to 6% of the oven-dry weight of the aggregate.
6.5.2 The shotcrete shall be thoroughly mixed by machine and then passed through a sieve to remove all large particles before placing in the hopper of the cement gun. The mixture shall not be permitted to become damp. Each batch should be entirely discharged before recharging has begun. The mixer shall be cleaned thoroughly enough to remove all adherent materials from the mixing vanes and from the drum at regular intervals.
6.5.3 Mixed material shall be used within 45 minutes after adding cement or shall be disposed of at contractor’s expense. Rebound material shall not be reused.
6.5.4 Water shall not be added to the mix before it enters the cement gun. Quantities of water shall be controlled by a valve at the nozzle of the gun. Water content shall be adjusted as required for proper placement, but shall in no case exceed four gallons per sack of cement, including the water contained in the aggregate. Contractor shall not add water other than at the nozzle.
6.5.5 The accelerating additive shall be added immediately prior to depositing the materials in the placing equipment or if in liquid form may be accurately proportioned into the water supply at the application nozzle. Dry additives shall be accurately proportioned and thoroughly mixed with the other ingredients.
6.5.6 Remixing or tampering shall not be permitted.
6.5.7 Mix proportions shall be controlled by weight batching or by volume batching meeting the requirements (except water in case of dry-mix equipment) at a rate that will provide adequate production and with an accuracy that will ensure uniformity of batches. Weighing equipment shall be capable of batching with the accuracy specified in ASTM C-94. Volumetric equipment shall be capable of batching with the accuracy specified in ASTM C-685.
6.6 Ready Mix Concrete
6.6.1 Ready-mixed concrete shall comply with ASTM C-94, except that it may be delivered to the shotcrete equipment in the dry state if the equipment is capable adding the water and mixing it satisfactorily with the dry ingredients, in which case it shall comply with ASTM C-685.
6.7 Installation of Steel Reinforcement
6.7.1 Unless otherwise specified, welded wire fabric shall be used as reinforcement. The option of using equivalent deformed bars is acceptable, if minimum depth of concrete over reinforcing will be obtained.
6.7.2 Reinforcement shall not be less than 1 inch from the surface on which the shotcrete is to be placed and there shall not be less than 1 inch between the reinforcement and the final surface of the gunite.
6.7.3 Wire fabric shall be rolled into cylinders and placed circumferentially on hook bolts or support anchors. Anchors shall be 24-inch centers each way.
6.7.4 Mesh or fabric shall be lapped at least one full mesh longitudinally and the same width in inches transversely.
6.7.5 Laps shall be tied with 16 gauge wire at 12 inch spacings.
6.7.6 The full area of reinforcement shall be held firmly on position by means of 16 gauge wire ties in a rigid position to withstand impact of the shotcrete application without displacement.
6.7.7 Installation of reinforcement shall be inspected and approved by the Engineer prior to the commencement of any shotcrete placement operations. This shall not, however, release contractor in any way from his responsibility for ensuring the proper performance of work.
6.7.8 Contractor shall provide ¼ inch by 3 inch hook bolt anchors, supports and other accessories from the Chicago Expansion Bolt Company to hold welded wire fabric in proper position while shotcrete is being placed. Use steel, 16 gauge tie wire to secure the fabric at laps and supports.
6.7.9 Contractor shall provide mechanical connections that develop at least 125 perfect of the specified yield strength of the steel in tension.
6.7.10 Install #4 reinforcing steel bars at 8” center, 24” long and 2 #4 reinforcing steel bars longitudinally at the crown for the entire length of pipe line segments tied to the wire mesh. Reinforcing steel shall be placed in accordance with CRSI “Recommended Practice for Placing Reinforcing Bars.” Reinforcing placement shall be reviewed by the owner’s representative before concrete is placed. (Note: Typical language for installation including steel bar reinforcement. Engineer shall specify the use of steel bars and steel placement on project specific basis.)
6.7.11 Reinforcement shall be clean and free from loose mill scale, loose rust, oil or other coatings that interfere with bonding.
6.8 Placement of Shotcrete
6.8.1 Contractor shall place shotcrete using suitable delivery equipment and procedures that will result in shotcrete in place with minimum thickness of 2 inches with an allowable variance of 10 percent unless otherwise shown.
6.8.2 Contractor may use either wet mix or dry mix method of applying shotcrete. Contractor shall control thickness, method of support, air pressure and/or water content of shotcrete to preclude sagging or sloughing off. Contractor shall discontinue shotcreting or provide suitable means to screen the nozzle stream if wind or air currents cause separation of the nozzle stream during placement.
6.8.3 Contractor shall dampen absorptive substrate surfaces prior to placement of shotcrete to facilitate bond and to reduce the possibility of shrinkage cracking developing from premature loss of mixture water.
6.8.4 Contractor shall fill with sound material all corners and any areas where rebound cannot escape or be blown free. Contractor shall complete the corners between the web and the flanges of structural steel before application to the flat areas.
6.8.5 Contract shall broom or scarify the surface of freshly placed shotcrete to which, after hardening additional layers of shotcrete are to be bonded. All surfaces shall be dampened just prior to application of succeeding layers.
6.8.6 Contractor shall provide a supply of clean, dry air adequate for maintaining sufficient nozzle velocity for all parts of the work and, if required, for simultaneous operation of a suitable flow pipe for cleaning away rebound.
6.8.7 Rebound losses shall not exceed an average of 25% by weight of the material passing through the nozzle. Rebound shall be removed and disposed of at contractor’s expense of a daily basis.
6.8.8 If the flow of material at the nozzle is not uniform and slugs, sand sports, or wet slough results, the nozzle man shall direct the nozzle away from the work until the faulty conditions are corrected. Such defects shall be replaced as the work progresses at no increase in contract price.
6.8.9 Shotcreting shall be suspended if air velocity separates the cement from the sand at the nozzle.
6.8.10 The nozzle shall be held at the proper distance (minimum 3 feet except in close quarters) and at the proper angle to secure maximum compaction with minimum loss of material. This angle shall be as near perpendicular to the surface as work permits.
6.8.11 Construction joints or end of day’s work joints shall be sloped off to a thin, clean 45 degree slope. Before placing the adjoining work, clean the sloped portion and adjacent shotcrete and then moisten and scour with an air jet.
6.8.11.1 Placement around Reinforcing
Contractor shall not place shotcrete through more than one layer of reinforcing steel rods or mesh in one application. Contractor shall test to ascertain if any voids or sand pockets have developed around or behind the reinforcement by probing with an awl or other pointed tool after the shotcrete has achieved its initial set, by removal of randomly selected bars or by coring or other suitable means.
6.8.11.2 Line and Thickness Control
-Prior to the application of the first layer of shotcrete, contractor shall furnish and install adequate ground wires, measuring pins, or other approved means to establish the thickness, surface planes, and finish lines of the shotcrete. Contractor shall maintain specified tolerances by keeping ground wires secure and taut.
-Pins shall be non-corrosive and so designed as not to cause infiltration of water through the shotcrete. Pins shall be installed on 5-foot centers in each direction and at the other locations as may be directed by the Engineer.
6.8.11.3 Placement Precautions
-Contractor shall not place shotcrete if dying or stiffening of the mix takes place at any time prior to deliver to the nozzle. No rebound or previously expended material shall be used in the shotcrete mix.`
-Contractor shall remove all overspray or rebound prior to final set and before placement of shotcrete material on such adjacent surface.
-Contractor shall not apply shotcrete in areas where running water exists.
-Contractor shall protect shotcrete from freezing during installation and during curing period.
-Contractor shall protect in-place reinforcing from excessive construction traffic and other work.
6.9 Surface finish
6.9.1 Contractor shall bring the shotcrete to an even place and well formed corners.
6.9.2 After the body coat has been placed, the surface shall be trued with a thin-edged screed to remove high areas and expose low areas. Low areas shall be properly filled with concrete to ensure a true, flat service.
6.9.3 After the concrete surface has been trued, the entire surface shall receive a rubber float and brush application resulting in a fine brush smooth finish parallel to the direction of the flow.
6.10 Lateral Reinforcement or Abandonment
6.10.1 Contractor is responsible for identifying all active and abandoned laterals and their locations. The contractor shall submit a lateral abandonment plan prior to beginning work. The plan shall include the locations and sizes of all laterals and where they are active or abandoned.
6.10.2 It shall be the contractor’s responsibility to determine and to assure that all live laterals are connected. Laterals reinstatement shall be completed from inside the pipe. Excavation for lateral reinstatement shall be permitted.
6.11 Testing and Acceptance
6.11.1 Contractor shall be responsible for testing the strength of the shotcrete according to the following:
6.11.1.1 Cores shall be cut from the finished gunite construction and tested in accordance with ASTM C-42. Contractor shall provide standard core test specimens at a rate of two each per 50 linear feet of lining. These specimens shall have a minimum length equal to twice the diameter (L/D=2) and shall expose the bond between the shotcrete and the pipe line. They shall be cored from the completed work and shall be tested at contractor’s expense in accordance with the aforementioned specification. Test specimens shall be soaked for a minimum of 40 hours prior to testing.
6.11.1.2 The 28-day compressive strength of each core shall not be less than 5,000 psi.
6.11.1.3 In addition to testing the finished shotcrete construction, contractor shall make 2 test panels per day, one in the afternoon, at least 24 inch x 24 inch. Provide the same reinforcement as in the structure in at least half of the panel to demonstrate for proper embedment of reinforcing steel. Fabricate test panels to the same thickness as the structure, but not less than 3 inches. Contractor shall take at least six cores from the panels for testing of compressive strength. Test results shall be provided to owner for both 7-day and 28 day compressive strength results.
6.11.1.4 Contractor shall plug all voids caused by the coring operation by the use of material equal to the in-place shotcrete with workmanship that ensures continuity to the lining with respect to water tightness, strength and appearance.
GROUTING SPECIFICATIONS
1.1 The work covered by these specifications consists of furnishing all labor, equipment, appliances, and materials, and performing all operations in connection with the injection of grout complete in accordance with the drawings, specifications and subject to the terms and conditions of the contract.
1.2 The purpose of this specification is to produce a grout, when injected in place, which will be dense, fill voids, and stabilize the subgrade.
G-2 Materials
2.1 Cement: Type 1 or Type 2 Portland meeting ASTM C-150.
2.2 Water: Water shall be potable. Municipal source. Water will be considered as weighing 8.33 pounds per gallon and 7.5 gallons per cubic foot.
2.3 Fly Ash: Class “C” Fly Ash, meeting ASTM C-618 may be added to the mix at the grout pump operator’s discretion to aid in pumpability. If added, the Fly Ash shall not exceed 10% of the weight of the cement
2.4 Other Admixtures: No other admixtures will be used unless approved.
G-3 Mix Design
3.1 Grout Mix: The basic grout mix will be cement and water proportioned in the ratio of 1 cubic foot (one bag or 94 pounds) of cement to 1 cubic foot (7.5 gallons) of water. The mix ratio may be modified by the grout pump operator as required to ensure filling of the voids and/or stabilizing the subgrade.
3.2 Yield: For quantity determination on cubic foot (1bag or 94 pounds) of cement when proportioned with one cubic foot (7.5 gallons) of water is deemed to yield 1.5 cubic feet of grout.
G-4 Grout Equipment
4.1 Pump: Grout Pump will be of the positive displacement type and will be capable of producing adequate pressure to penetrate the area.
G-5 Injection Ports
5.1 Grout Shafts: Location of grout shafts shall be in areas where voids or unstable subgrade occurs. These shall be a minimum of 1 ¼ – inch diameter and sufficient to receive packers and shut-off-valves.
G-6 State Grouting
6.1 Stages: To minimize the quantity of grout required, grouting will be accomplished in stages. The grout placed in the first stage will be accomplished in stages. The grout placed in the first stage will be observed carefully to ensure that grout is not pumped excessively into channels and of no benefit to the area. A minimum of two stages will be used with a 4-hour minimum time between each stage at any particular location. Additional stages of grouting will be accomplished if required.
G-7 Experience
7.1 Personnel: Before starting the work on the project, the contractor must satisfy the owner that the foreman and grout pimp operator have done satisfactory work in similar capacities elsewhere for a sufficient period of time to be fully qualified to properly perform the work in accordance with the requirements of the related specifications.
A. Foreman shall have had at least 4 years experience in similar work.
B. Pump operator shall be qualified having had at least 2 years experience in similar work.
1.1 The work covered by these specifications consists of furnishing all labor, equipment, appliances and materials, and performing all operations in connection with the injection of grout complete in accordance with the drawings, specifications and subject to the terms and conditions of the contract.
1.2 The purpose of this specification is to produce a grout, when injected in place, which will be dense, fill voids, and stabilize the subgrade.
G-2 Materials
2.1 Cement: Type 1 or Type 2 Portland meeting ASTM C-150.
2.2 Water: Water shall be potable. Municipal source. Water will be considered as weighing 8.33 pounds per gallon and 7.5 gallons per cubic foot.
2.3 Fly Ash: Class “C” Fly Ash, meeting ASTM C-618 may be added to the mix at the grout pump operator’s discretion to aid in pumpability. If added, the Fly Ash shall not exceed 10% of the weight of the cement
2.4 Other Admixtures: No other admixtures will be used unless approved.
G-3 Mix Design
3.1 Grout Mix: The basic grout mix will be cement and water proportioned in the ratio of 1 cubic foot (one bag or 94 pounds) of cement to 1 cubic foot (7.5 gallons) of water. The mix ratio may be modified by the grout pump operator as required to insure filling of the voids and/or stabilizing the subgrade.
3.2 Yield: For quantity determination on cubic foot (1bag or 94 pounds) of cement when proportioned with on cubic foot (7.5 gallons) of water is deemed to yield 1.5 cubic feet of grout.
G-4 Grout Equipment
4.1 Pump: Grout Pump will be of the positive displacement type and will be capable of producing adequate pressure to penetrate the area.
G-5 Injection Ports
5.1 Grout Shafts: Location of grout shafts shall be in areas where voids or unstable subgrade occurs. These shall be a minimum of 1 ¼ – inch diameter and sufficient to receive packers and shut-off-valves.
G-6 State Grouting
6.1 Stages: To minimize the quantity of grout required, grouting will be accomplished in stages. The grout placed in the first stage will be accomplished in stages. The grout placed in the first stage will be observed carefully to insure that grout is not pumped excessively into channels and of no benefit to the area. A minimum of two stages will be used with a 4-hour minimum time between each stage at any particular location. Additional stages of grouting will be accomplished if required.
G-7 Experience
7.1 Personnel: Before starting the work on the project, the contractor must satisfy the owner that the foreman and grout pimp operator have done satisfactory work in similar capacities elsewhere for a sufficient period of time to be fully qualified to properly perform the work in accordance with the requirements of the related specifications.
A. Foreman shall have had at least 4 years experience in similar work.
B. Pump operator shall be qualified having had at least 2 years experience in similar work.
Specifications for the Rehabilitation of Corrugated Metal Pipe using Shotcrete
I. Scope
A. The work covered by these specifications consists of furnishing all labor, equipment, appliances, and materials, and performing all operations in connection with the rehabilitation of corrugated metal pipe with shotcrete, complete in drawings and subject to the terms and conditions of the contract.
B. Shotcreting shall conform to all requirements of “Guide to Shotcrete”, published by the American Concrete Institute, Detroit, Michigan, except as modified by these specifications.
C. Reinforcement shall be incorporated in the shotcrete as required and shall be furnished and placed in accordance with the provisions of these specifications.
D. The purpose of this specification is to obtain a dense and durable concrete having the specified strength.
II. Composition
A. Shotcrete shall be composed of Portland cement, aggregate and water so proportioned as to produce a concrete suitable for a pneumatic application.
III. Strength Requirements
A. Shotcrete shall be supplied by Ready Mix supplier. The shotcrete shall be extremely strong, dense and resistant to weathering and abrasion. Shotcrete shall have a minimum 28-day strength of 4,000 psi.
IV. Materials
A. Portland Cement
1. Cement shall be Type I/II Portland Cement conforming to all of the requirements of the American Society for Testing Materials Standard Specifications, latest serial designation C-150.
B. Fine Aggregate
1. Fine aggregate shall be natural, siliceous sand consisting of hard, clean, strong, durable and uncoated particles, conforming to the requirements of American Society for Testing Materials Standard Specifications, Latest Serial Designation C-33 for Concrete Aggregates.
2. Fine aggregate shall not contain less than three percent or more than six percent of moisture.
3. Fine aggregate shall be evenly graded from fine to coarse and shall be within the following limits:
Passing No. 3/8 Sieve 100%
Passing No. 4 Sieve 95% to 100%
Passing No. 8 Sieve 80% to 100%
Passing No. 16 Sieve 50% to 85%
Passing No. 30 Sieve 25% to 60%
Passing No. 50 Sieve 10% to 30%
Passing No. 100 Sieve 2% to 10%
C. Water
1. Water used in mixing shall be fresh, clean, and free from injurious amounts of oil, acid, alkali, vegetable, sewage, and/or organic matter.
D. Reinforcement
1. Reinforcement bars shall conform to the latest requirements of ASTM Standard Specifications, Serial Designation A-615 for Deformed Billet-Steel Bars for Concrete Reinforcement. Unless shown otherwise on the plans, all bars shall be Grade 40.
2. Steel mesh reinforcement shall be electrically welded, cold drawn, mild steel fabric conforming to the latest requirements of ASTM Standard Specifications, Serial Designation A-185 for Welded Steel Wire Fabric for Concrete Reinforcement. Mesh can be fabricated from cold-drawn steel wire conforming to the requirements of the latest ASTM Standard Specifications, Serial Designation A-82. Unless otherwise shown on the plans, mesh shall be 2 x 2 – W0.9 x W0.9 (2 x 2 – 12/12) galvanized welded wire fabric.
3. Polypropylene fibers shall be used as indicated on the drawings in lieu of wire mesh. Use only 100 percent virgin polypropylene fibers containing no reprocessed olefin materials. Fiber manufacturer must document evidence of 5-year satisfactory performance history: ASTM C-1116 (Ref.: ASTM C-1018).
V. Sampling and Testing Cement and Aggregate
A. Where reputable cement and aggregate suppliers maintain regular recognized testing services, certified copies of such tests would be accepted by the Owner. However, in any case of doubt as to the accuracy and/or adequacy of such tests, the Owner may require that cement and aggregates be tested by a recognized commercial testing laboratory that has been selected by the Contractor and approved by the Owner. The testing laboratory shall also certify that the materials covered by the report comply in all respects with these specifications.
B. Shotcrete is supplied by local Ready Mix suppliers and pumped via contractor’s equipment. The Shotcrete is typically an existing mix developed by the Ready Mix supplier based on standard raw materials (aggregate, sand, and cement).
C. Cylinders shall be taken during the pour from the Ready Mix truck shoot. Slump can also be tested for consistency. Cylinders, typically 4”x8”, shall be cast and tested at 7 and 28-day intervals.
VI. Surface Preparation
A. All areas to receive pneumatic concrete shall be cleaned by flushing or scouring with water and compressed air jets to assure the removal of all loose particles.
B. To ensure, the newly prepared surface shall be thoroughly moistened with water prior to application of shotcrete. In no instance shall shotcrete be applied in an area where free running water exists.
VII. Application
A. Shotcrete shall not be placed on a frozen surface or during freezing weather unless means are used to elevate the area temperature, which is acceptable. Shotcrete shall not be placed when anticipated the temperature during the following 24 hours will drop below 32 degrees Fahrenheit, unless the temperature is maintained.
B. The sequence of application may be from bottom to top or vice versa if rebound is properly removed.
C. Voids shall be filled first. “Shooting” shall be from an angle as near perpendicular to the surface as practicable, with the nozzle held approximately 3 feet from the work (except in confined space). If the flow of material at the nozzle is not uniform and slugs, sand spots, or wet sloughs result, the nozzleman shall direct the nozzle away from the work until the faulty conditions are corrected. Such defects shall be replaced as the work progresses.
D. Shotcreting shall be suspended if:
1. Air velocity separates the paste from the aggregate at the nozzle.
2. Temperature approaches freezing and the newly placed shotcrete cannot be protected.
E. Shotcrete can be applied in one or more layers to such total thickness as required restoring the area as detailed over the original lines of the adjoining surface unless otherwise specified. All cavities, depressions, washouts and similar failures shall be rebuilt to original lines by use of shotcrete reinforced with wire mesh. Where the cavity exceeds four inches in depth, a layer of mesh shall be used for every four inches of depth of shotcrete. However, in no case shall wire mesh be placed behind existing reinforcement.
F. The time interval between successive layers in sloping vertical or overhanging work must be sufficient to allow initial, but not final, set to develop. At the time the initial set is developing, the surface shall be cleaned to remove the thin film of laitance in order to provide a perfect bond with succeeding applications.
VIII. Construction Joints
A. Construction joints or day’s work joints shall be sloped off to a thin, clean, regular edge preferably at a 45-degree slope. Before placing the adjoining work, the slope portion of adjacent shotcrete shall be thoroughly cleaned as necessary, then moistened and scoured with an air jet.
IX. Surface Finish
A. Nozzleman shall bring the shotcrete to an even plane and to well-formed corners be working up to ground wires or other guides, using somewhat lower placing velocity than normal.
B. After the body coat has been placed, the surface shall be trued with a thin-edge screed to remove high areas and expose low areas. Low areas shall be properly filled with concrete to ensure a truly flat surface.
C. After the concrete surface has been brought to a specified depth, the surface finish shall be either a ‘broom’ or ‘float’ finish – unless a special type finish is specified per the drawings.
X. Curing
A. Curing shall be in accordance with paragraph 8.7 ACI – 506-R, depending upon atmospheric condition.
B. Keep water off of shotcrete until shotcrete sets – typically 12 hours.
C. If water velocity is too great, extend introducing flow onto the shotcrete until the final set is obtained.