8−105preparing bonding surfaces of concrete; preparing and installing bonding agent; replacing the deteriorated concrete with a specified repair material; and finishing and curing to the lines and grades specified at the locations indicated on the Pl ans, all in accordance with these Specifications and/or as may be directed by the Engineer.
817.02 Materials.
817.02.1 Pneumatically Applied Mortar (Shotcrete). Materials for shotcrete shall conform to the
applicable requirements of SECTION 601, SECTION 602 and SECTION M.02, respectively, of these Specifications, except as modified herein. Shotcrete shall be produced by either the wet mix process or the dry mix process and conform to the following requirements unless otherwise indicated on the Plans: Material or Property Value Compressive Strength at 28 days, f c' (psi) As indicated on plans Maximum Water/Cementitious Ratio 0.45 Minimum Cement Factor (lbs./cy.) 500 Air Content (percent) 5-9 Slump (inches) 1 to 3
a.Mixture Proportions . The Contractor shall determine, recommend and submit a mix proportion for acceptance, 28-day compressive strength results, water-cement ratio and source of materials. The Contractor shall select mix proportions on the basis of compressive strength tests of specimens continuously moist cured until tested at 28 days or different test age if so specified in accordance with ASTM C1604. Shotcrete core specimens shall be sampled from shotcreted test panels not earlier than 3 days after shotcreting. Sampling and testing of shotcrete cores shall be in accordance with ASTM C1604. Combined aggregate gradation (fine and coarse) shall meet either gradation #1 or #2 of Table 1.1 of ACI 506R, Section 1.5 as indicated on the Plans. Premixed and prepackaged concrete products specifically manufactured as a shotcrete product may be provided for the dry mix shotcrete process only as approved by the Engineer. The packages shall contain cement and aggregates conforming to the materials requirement of this Specification and the product must be listed on the Department's Approved Materials List. 817.02.2 Patching Mortar. Patching mortar shall conform to the requirements of ASTM C928; “Rapid Hardening or Very Rapid Hardening Mortar” as indicated on the Plans, and be listed on the Department's Approved Materials List. The mortar shall be a non-shrink type and chloride free. Repair mortars not previously approved must be submitted for approval to the Engineer 45 days before intended use. All materials shall be used in accordance with manufacturer's recommendations. 817.02.3 Reinforcement. All reinforcement shall be galvanized and conform with the requirements of Section M.05 . 8−106
817.02.4 Bonding Agent. A bonding agent shall be used when mortar repairs are specified or
indicated on the Plans. The bonding agent shall be as specified and/or as indicated on the Plans, and be listed on the Department’s Approved Mate rials List. Bonding agents not previously approved must be submitted for approval to t he Engineer 45 days before intended use. All materials shall be used in accordance with manufacturer's recommendations. 817.02.5 Form and Cast-in-Place Concrete. Concrete shall be as indicated on the Plans and conform to the applicable provisions of SECTION 601, Portland Cement Concrete of these specifications. 817.03 CONSTRUCTION METHODS.
817.03.1 Surface Preparation (All Repair Methods). All deteriorated soft or honeycombed concrete shall be removed from the areas to be repaired by means of suitable power and hand tools to a uniform depth, sufficient to expose a bonding surface of sound material. Power tools that cause or may cause over-breakage of concrete are prohibited. Pneumatic/chipping hammers shall
not be heavier than the nominal 30-pound class. Pneumatic/chipping hammers or mechanical chipping tools, to remove concrete within tw o inches beneath or around re inforcing steel designated to remain, shall not be heavier than the nominal 15- pound class. Tools shall not contact reinforcing steel to remain. The boundaries of areas to be removed where indicated on the Plans or as directed by the Engineer, shall be saw cut square to a minimum depth of 1 inch, unless otherwise noted on the Plans. Thin, tapered or feathered edges are prohibited. In areas where reinforcing steel is found to be surrounded by deteriorated concrete or where at least one-half of the rebar surface area is exposed, the depth of concrete removal shall be such as to include all deteriorated concrete but not less than that depth necessary to allow for one inch minimum annular clearance around the reinforcing bars. All corroded reinforcing bars to remain within the concrete removal boundaries shall be thoroughly cleaned by sandblasting or by other suitable methods approved by the Engineer to remove all rust. Those bars that have lost 1/4 or more of their original diameter shall be supplemented by new bars spliced in place. New bars shall be lapped as indicated on the Plans to develop the full strength of the bar. Additional concrete removal may be necessary to provide this lap. Dual bars of equivalent or greater cross-sectional area may be used. All newly exposed concrete repair surfaces sha ll be free of loose particles and other foreign material. The repair areas shall be thoroughly cleaned and be left roughened by the use of sandblasting, compressed air, air and water blasting, steam, wire brushing, or by other methods approved by the Engineer. The Contractor may use one or all of the various means of cleaning the repair areas as approved or as ordered by the Engineer. Care shall be taken during the removal of the designated portions of the structure to avoid damaging the portions that are to remain in place. Any damage caused by the Contractor to the existing structure that is designated to remain in place shall be repaired or replaced by the Contractor at its own expense to the satisfaction of the Engineer. Regardless of the method of removal, if in the opinion of the Engineer the removal operation causes excessive damage to 8−107portions of the concrete which are to remain, the Contractor shall cease his operations until such time that an alternate removal method has been proposed by the Contractor and has been approved by the Engineer. Claims for additional time or compensation due to such cessation of operations will not be approved. The Contractor shall ensure that no debris or any other material falls onto the roadway or waterway below the bridge. Should debris or materi al fall onto the roadway or waterway, such shall be removed immediately and all work shall stop until such time as a revis ed procedure of operation has been submitted and approved by the Engineer. All dam ages or injuries as a result of debris or material falling shall be the responsibility of the Contractor. All such debris and materials shall be removed and legally disposed of off the project site. Storing or burying of material or debris on site is not allowed. The surface against which mortar is to be placed shall be kept wet for at least one hour and then allowed to dry to a saturated surface dry (SSD) condition just prior to application of the repair material. Where bonding agents are specified for use, they shall be applied in accordance with the manufacturer’s recommendations. The Contractor shall be aware of the contact time, as per the manufacturer’s recommendation after the placement of the bonding agent, and shall perform the necessary coordination between the associated construction activities, primarily the surface preparation, the erection of forms, and the delivery and placement of concrete. The Contractor shall take measures to ensure that the contact time is not exceeded. If the contact time is exceeded, the bonding agent shall be re-applied in accordance with the manufacturer’s recommended procedures for reapplication, at no additional cost to the State. 817.03.2 Placement of Reinforcing. Repairs less than 1½-inches depth will not require wire mesh reinforcement unless otherwise directed by the Engineer. In cases where the thickness of the repair mortar exceeds 1½-inches depth and existing bar reinforcement is available, galvanized wire mesh reinforcement shall be attached to the bars with tie wire. If existing rebar is not available, wire mesh reinforcement shall be installed by means of mechanical concrete anchors in accordance with the requirements of Table 1. For areas where the repair exceeds 4 inches depth, a single layer of wire mesh shall be used to reinforce each 2-inch thickness of patch material. Table 1 Size and Spacing of Anchors Thickness Overhead Vertical Top Horizontal of Surfaces Surfaces Surfaces Placement Dia.(in.) Dia. (in.) Dia. (in.) (in.) Spacing (in.) Spacing (in.) Spacing (in.) 1½ to 4 1/4 at 24 1/4 at 24 1/4 at 36 4 to 5 1/4 at 20 1/4 at 24 1/4 at 36 5 to 6 3/8 at 17 3/8 at 21 3/8 at 36 over 6 3/8 at 16 3/8 at 20 3/8 at 36 8−108 Mechanical concrete anchors shall be galvanized, hooked type expansion bolts to be approved by the Engineer. The exposed end of each anchor shall have at a minimum a right-angle bend for engaging reinforcement. At least three anchors shall be used in each individual patch area. If any reinforcement is damaged by the Contract or during the repair procedure, it shall be replaced at the Contractor's expense, as directed by the Engineer. 817.03.3 Application of Pneumatically Applied Mortar (Shotcrete).
a.Submittals . Submittal shall include shop drawings, details, material Certificates of Compliance including mill test reports, mix designs, Quality Control (QC) Plan to include but not be limited to staff qualifications, construction procedures, detailed construction sequencing plans, and details of temporary debris shields. Submittals shall be submitted for review and approval by the Engineer a minimum of 45 days prior to the commencement of work. The Contractors QC Plan shall detail the following:
1.Number and qualifications of personnel involved in shotcrete placement 2. Surface preparation method 3. Equipment and materials for placement, finishing and curing 4. Placement method including application rates, plans for multiple layers where applicable, and methods for achieving required thickness and finish
5.Curing method 6. QC testing and inspection personnel 7. QC testing and inspection methods and frequencies including determinations of thickness and strength of placed shotcrete and checking for hollow areas and surface defects
8.Methods for correcting deficiencies in shotcrete thickness, strength, hollow areas and surface defects The Contractor shall submit documentation substantiating that project personnel have appropriate qualifications. Inadequate documentation or substantiation of personnel qualifications will be cause for rejection of the QC Plan. Changes to previously approved personnel must be approved in writing. Shotcreting nozzle operators shall have at least one year of experience in the application of shotcrete and completed at least three projects of comparable nature or work under the immediate supervision of a foreman or instructor with at least two years of such experience. Documentation of nozzle operator’s experience shall be submitted with the QC Plan. Work shall not begin until the Contractor's QC Plan is approved. The Engineer will suspend the work if the Contractor substitutes unqualified personnel for approved personnel during construction or if work is found to be unsatisfactory during placement of shotcrete. Claims for additional time or compensation due to such cessation of operations will not be approved.
b.Batching and Mixing . Aggregate and cement may be batched by weight or by volume. Mixing equipment shall be capable of thoroughly mixing the materials in sufficient quantity to maintain placing continuity. Ready mix shotcrete shall comply with the requirements of SECTION 601. 8−109c. Delivery Equipment . The shotcrete shall be applied by pneumatic equipment that sprays the mix onto the prepared surface at the velocity needed to produce a compacted dense homogeneous mass. The velocity of the material as it leaves the nozzle must be maintained at a uniform rate determined for the given job conditions to minimize rebound.
1.Dry Mix Process . The delivery equipment shall deliver a continuous, smooth uniformly mixed material to the nozzle. The nozzle shall be equipped with a water ring and valve to permit adjustment of the water. The nozzle shall be capable of delivering a conical discharge stream.
2.Wet Mix Process . Only pneumatic-feed type delivery equipment will be allowed.
d.Pre-Construction Testing . Test panels shall be made by each application crew using the equipment, materials, mixture proportions and procedures proposed for the job prior to the commencement of the work. A test panel at least 30" x 30" shall be made for each mixture being considered and for each shooting position to be encountered in the job. The test panels shall be fabricated to the same thickness as in the structure, but not less than 4 inches. Take at least five, 3-inch minimum diameter cores from each panel for testing in accordance with ASTM C1604. Samples for testing shall be obtained by the Contractor in the presence of the Engineer, and tested by the Engineer.
e.Placement of Shotcrete. Shotcrete shall be applied with the same equipment and the same technique as used to construct the approved test panels. The nozzle operator constructing the test panels shall be the same operator used in placing shotcrete in the work. The shotcrete shall be applied as dry as practicable to prevent shrinkage cracking, sagging and sloughing off. Shooting guide strips or wires shall be employed to ensure square corners, straight lines and a plane surface of mortar, except as otherwise indicated on the Plans or approved by the Engineer. They shall be so placed to minimize trapping of rebound. The re-use of rebounded materials is not allowed. Thickness measuring pins shall be installed on 5-foot centers in each direction. The pins shall be non-corrosive. Other methods to establish if the required minimum thickness of shotcrete is being applied may be approved if the Contractor can satisfactorily demonstrate the reliability of these other methods. A sufficient number of mortar coats shall be applied to obtain the required thickness. On vertical and overhead surfaces, the thickness of each coat shall not be greater than 1 inch, except as approved by the Engineer, and shall be so placed that it will neither sag nor decrease the bond of the preceding coat. The time interval between successive layers in sloping, vertical or overhanging work, shall be sufficient to allow initial set but not final set to develop. At the time initial set is developing, the surface shall be cleaned to remove the thin film of laitance in order to provide for a bond with succeeding applications. Rebound or accumulated loose sand shall be removed from the surface by brooming or scraping to be covered prior to placing of the original or succeeding layers of mortar and shall not be embedded in the work. All laitance which has been allowed to take final set shall be removed by sandblasting and thoroughly cleaning the surfaces. To achieve an SSD condition, care shall be taken to thoroughly wash down all previously hardened concrete with water and compressed air before shooting new material. The wire fabric reinforcement shall be positioned to minimize vibration while the shotcrete is being applied. Lap mesh one and a half squares in both directions. Tie wires shall be bent flat in 8−110 the plane of the mesh and not form large knots. The shotcrete shall be applied from the bottom up to prevent accumulation of rebound on the surface still to be covered. Horizontal and vertical corners and any area where rebound cannot e scape or be blown free shall be filled first. Nozzle shall be held at such distance and angle to place material behind reinforcement before material is allowed to accumulate on its face. Do not place shotcrete through more than one layer of reinforcing steel in one application. Unless suitable means to screen the nozzle is provided, discontinue shotcreting if wind or air currents will cause separation of the stream during placement. The Contractor shall check in the presence of the Engineer for hollow areas by hammer sounding. Hollow areas, and areas containing any other non-conforming work or defects, are deemed to be deficient areas. An approved repair method including proposed mitigation measures shall be used to correct deficient areas. The repair method shall be submitted by the Contractor for review and approval by the Engineer prior to commencement of any repair work. Deficient areas shall be corrected at the Contractor's expense. At the discretion of the Engineer, deficient areas shall be repaired after initial placement of the shotcrete is completed. All shotcrete defects, including but not limited to, lack of uniformity, segregation, honeycombing, lamination, or which contains any dry patches, slugs, voids, or sand pockets shall be removed and replaced with fresh shotcrete at the Contractor's expense.
f.Acceptance Testing. The Contractor shall prepare one test panel for every 50 cubic yards of shotcrete placed or one panel per one days production, whichever is less. . Test panel shall have minimum dimensions of 24" x 24" x 4" gunned in the same position as the work represented. Panels shall be gunned during the course of the work by the previously qualified nozzle operator. Cure the panels and obtain a minimum of three cores as described under "Preconstruction Testing.” Cores will be tested by the Engineer in accordance with the requirements listed under "Preconstruction Testing.”
g.Limitation of Mixing . Shotcrete shall be placed in a ccordance with the temperature and weather conditions listed in Section 601 .
h.Finish . All exposed surfaces shall be finished straight and true, approximating the original contour as close as practicable. The final finish shall be as indicated on the plans.
i.Curing . Shotcrete shall be cured in accordance with Section 601 . Curing compounds shall not be used on any surfaces against which additional shotcrete or other cementitious finishing materials are to be bonded. 817.03.4 Application of Patching Mortar. Concrete patching mortar shall be mixed, applied and cured in strict accordance with the manufacturer's recommendations. All exposed surfaces shall be finished straight and true, approximating the original contour as close as practicable. The final finish shall be as indicated on the plans.
817.03.5 Application of Form and Cast-in-Place Concrete
8−111a. General. Repairs accomplished by the form and cast-in-place method shall be performed in accordance with the applicable requirements of Section 808, CAST-IN-PLACE STRUCTURE CONCRETE MASONRY of these specifications.
b.Bonding to Existing Surfaces. Prior to placing the Cast-in-Place Concrete, surfaces shall be prepped in accordance with these specifications or as indicated on the Plans.
c.Use of Self Consolidating Concrete (SCC) in Form and Cast-in-Place Concrete. SCC concrete may be used for form and cast-in-place concrete repairs or as indicated on the plans. Concreting procedures shall be performed by pers onnel experienced with the placement of SCC mixes. All repair areas shall be adequately formed to contain the proposed SCC material, and all resulting holes from the required formwork fasteners shall be properly filled with an approved cementitious material. Special care shall be taken so that the form is properly sealed against leaks, since SCC is more fluid than standard mixes. If excessive surface voids are observed when stripping a form, further placements of the SCC shall cease until the mix and/or placement problem is identified and corrected to the satisfaction of the Engineer.
d.Final Finish. All exposed surfaces shall be finished straight and true, approximating the original contour as close as practicable. The final finish shall be as indicated on the plans.
817.04 METHOD OF MEASUREMENT. "Repairs to Structure Concrete Masonry - Pneumatically
Applied Mortar", "Repairs to Structure Concrete Masonry - Patching Mortar" and "Repairs to Structure Concrete Masonry - Form and Cast-in-Place Concrete" will be measured by either the number of “Square Feet” or “Cubic Feet” of new concrete actually placed in accordance with the Contract Documents and/or as directed by the Engineer.
817.05 BASIS OF PAYMENT . The accepted quantities of "Repairs to Structure Concrete
Masonry - Pneumatically Applied Mortar", "Repai rs to Structure Concrete Masonry - Patching Mortar" and "Repairs to Structure Concrete Masonry - Form and Cast-in-Place Concrete" will be paid for at the respective contract unit prices per “Square Feet” or “Cubic Feet” as designated in the Proposal. The price so stated shall constitute full and complete compensation for all labor, materials, equipment, and all incidentals required to finish the work, comple te in place and accepted by the Engineer. Steel reinforcing bars and wire mesh reinforcement will be paid for separately by Force Account in accordance with the provisions of Subsection 109.04 of these specifications, or when applicable will be paid under the respective pay item for Reinforcing Steel Section 810 . SECTION 818 PORTLAND CEMENT CONCRETE BRIDGE DECK REPAIR
818.01 DESCRIPTION. This work consists of removing deteriorated concrete from bridge deck
surfaces, erecting form-work and the placement of new Portland cement concrete, all as indicated on the contract drawings and in accordance with these Specifications.
Source: Rhode Island Standard Specifications (Bluebook), 2024 Edition. Pages 439–445 of 826.