8−183SECTION 837 REPAIRS TO STRUCTURAL CONCRETE MASONRY WITH INTEGRALLY COLORED CONCRETE OR PATCHING MORTAR 837.01 DESCRIPTION . This work consists of removing all deteriorated, disintegrated, soft, honeycombed, fractured, or otherwise defective concrete and replacing it with integrally colored Portland cement concrete, or Portland cement mortar at locations indicated on the Plans or as directed by the Engineer. The concrete or mortar shall be of a color, texture and have aggregates from approved sources that closely match the predominant color, texture and aggregates of the existing concrete structure. Repairs shall include, but will not be limited to: removal and disposal of damaged concrete, cleaning and preparing of the bonding surface, cleaning of existing reinforcing steel, placing of additional reinforcing steel where required, application of a bonding agent slurry, and placement of new concrete repair materials to restore the structural elements to the original line, grade, and surface finish (color and texture). The Contractor shall submit a repair plan for each specific type of repair in accordance with the Plans and these Specifications. 837.02 MATERIALS . All proposed repair materials shall conform to the applicable requirements of Subsection 817.02 of these Specifications and/or be listed on the Department’s Approved Materials List. 837.02.1 Aggregate . The fine and coarse aggregates must be approved by the Engineer as to color and texture. 837.02.2 Integrally Colored Concrete . Integrally colored Portland cement concrete shall conform to the applicable requirements of SECTION 601 of these Specifications. The concrete classification and location used shall be as specified on the Plans and/or as directed by the Engineer. 837.02.3 Integrally Colored Patching Mortar . Patching mortar shall conform to the applicable requirements of Subsection 817.02.2 of these Specifications except that the maximum water cement ratio shall not exceed 0.40 by weight. The consistency of the mortar shall meet the application requirements. 837.02.4 Coloring Pigment . Coloring pigments for integrally colored concrete or patching mortar shall meet the requirements of ASTM C979 and be approved by the Engineer. Coloring pigments shall be used in accordance with the manufacturer’s recommendations. 837.02.5 Portland Cement Bonding Grout Slurry . The bonding grout slurry shall have the cement and mortar sand proportioned 1-to-1 by vo lume. Water shall be added in sufficient quantity to form a slurry.
837.02.6 Concrete Anchors. Mechanical concrete anchors shall be hooked type expansion bolts
galvanized in accordance with the applicable requirements of Subsection M.05.04.4, Para. d of these Specifications and shall be of a type approved by the Engineer. 837.02.7 Wire Mesh Reinforcement. Wire mesh shall be galvanized or epoxy coated, in accordance with ASTM A884, welded fabric No. 12 gauge wire (minimum size) spaced two inches 8−184 in each direction. Wire fabric shall conform to the requirements of Subsection M.05.02.1 of these Specifications.
837.02.8 Prototype (Samples) . The Contractor shall submit to the Engineer a prototype (1'x1'x3"
min.) showing color and texture of the concrete and/or mortar required. The Contractor shall also provide, in writing, the mix design and methods for obtaining any required surface finish (i.e., exposed aggregate, etc.) for each material. The prototype(s) must be submitted sufficiently in advance to allow for review and approval of the repair material. The prototypes must be approved in writing by the Engineer and, if necessary, by the Department’s Historic Preservation Specialist prior to use in production. 837.03 CONSTRUCTION METHODS . The Contractor shall inspect the structure to acquaint himself with the nature and extent of the work. Repair of concrete shall be performed with qualified workmen. The Engineer, at his option, shall witness all repair work. The Engineer shall be notified of any repair work no later than 24 hours prior to the scheduled repair work. 837.03.1 Surface Preparation .
a.General Requirements. All deteriorated, disintegrated, soft, honeycombed, fractured, or otherwise defective 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 as determined by the Engineer. Power tools that cause over-breakage of concrete will not be allowed. At the direction of the Engineer, the perimeter of the area to be repaired will be saw cut parallel to the horizontal and/or vertical axis of the element being repaired to a depth of at least 3/4- inch. Thin or feathered edges will not be permitted. Areas to be repaired shall be roughly circular or rectangular in outline. Re-entrant corners and shapes which include acute angles shall be avoided. 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 and not less than 1 inch minimum annular clearance around the reinforcing bars. Concrete removal shall extend along the reinforcement to where it is well bonded to sound concrete. All corroded reinforcing bars shall be thoroughly cleaned to remove all rust. Those bars that have lost 20 percent or more of their original cross-sectional area shall be supplemented by new equal diameter bars spliced in place. New bars shall be lapped sufficiently (30 diameters on both sides of the affected area) to develop the full design strength of the bar. If necessary, additional chipping will be required to provide this lap. Dual bars of equivalent or greater section may be used. Repairs less than 1½-inches thick will not require wire mesh reinforcement unless specified by the Engineer. In cases where the thickness is greater, the Engineer shall, in general, order that wire mesh reinforcement be used every 1½-inches in depth and provide a minimum of 3/4-inch cover. In such cases, after the surface preparation has been approved, concrete anchors to hold the wire mesh reinforcement shall be placed according to Table 1, unless otherwise directed by the Engineer. 8−185 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 All chipped areas, corroded rebars and concrete surfaces to be repaired shall be thoroughly cleaned by means of compressed air, sandblasting, waterblasting, steam, wire brushing or by other methods approved by the Engineer. The Contractor may use one or all of the various means of cleaning chipped areas as approved or as directed by the Engineer. Once all deteriorated concrete has been removed, the existing sound concrete shall be maintained in a clean, rough, and surface saturated moist condition until the concrete repair has been completed. When an epoxy-resin agent is specified, the prepared sound concrete surface shall be thoroughly dried prior to application of the epoxy-resin. 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 his own expense to the satisfaction of the Engineer. Mechanical concrete anchors shall be expansion bolts of a type approved by the Engineer. The exposed end of each anchor shall have a means of engaging reinforcement, either mechanical or hooked, and supplemented by the use of coated steel tie wire. If any reinforcement is damaged by the Contractor in his operations, the bar shall be replaced as required by the Engineer at the Contractor’s expense.
b.Forms . Forms shall be used for Portland cement concrete repairs whenever necessary to confine the concrete and shape it to the required lines. Such forms may partially require progressive installation as the concrete is placed as a result of confinements for placing concrete due to the location of the particular repair or restoration required. The forms shall have sufficient strength to withstand the pressure resulting from placing operations, shall be maintained rigidly in position, and shall be sufficiently tight to prevent loss of mortar from the concrete. The use of form oils is expressly forbidden. The Contractor shall use an alternate method or material for facilitating form release that will not cause discoloration or staining of the concrete. All such methods or materials are subject to the approval of the Engineer.
c.Weather Limitations. With respect to temperature and weather conditions, concrete repair materials shall be used in accordance with the applicable requirements of Subsection Nos.
601.03 4, 601.03.5, and 601.03.6; Limitations of Mixing, Cold Weather Concrete, and Hot
8−186 Weather Concrete , respectively.
837.03.2 Application .
a.Prime Coat. Prior to placing the concrete or mortar on a previously prepared and approved concrete surface, the entire area to be patched shall first be given a prime coat using a Portland cement bonding grout slurry. The consistency of the Portland cement bonding grout slurry shall be such that it can be applied with a brush on a prepared moist concrete surface in a thin (approximately 1/8-inch) even coating that will not run or puddle. Excess bonding grout will not be permitted to collect in pockets. The Portland cement bonding grout shall be applied to the concrete and the surfaces of the reinforcing bars, and into the spaces between the reinforcing bars and the prepared concrete surfaces. Care shall be exercised to ensure that all surfaces receive a thorough, even coating. The rate of bonding grout application shall be limited to that surface area which can be covered with new concrete or mortar before the bonding grout begins to dry out. Any grout that has dried or become unworkable, as determined by the Engineer, shall not be incorporated in the work. In the event drying does occur, the Contractor shall remove the bonding grout and place new bonding grout. The removal of the bonding grout shall be by a method approved by the Engineer and at the Contractor’s expense.
b.Placing and Consolidation . Integrally colored Portland cement concrete shall be placed, consolidated, and finished on a previously prepared surface as described in this Specification and to which a Portland cement bonding grout slurry has been applied. Integrally colored patching mortar shall be placed in ½-inch to 1-inch lift layers within 5 to 10 minutes after mixing water is added to avoid the rapid setup of the material after the application of the bonding grout slurry. If more than one lift layer is required to perform the repair, the previously placed lift layer will not be allowed to dry, and its surface shall be roughened prior to placing the next layer. Patching mortar shall not be applied when the ambient temperature is below 45 OF or is not in accordance with the manufacturer’s recommendations.
c.Finish . All exposed surfaces shall be finished straight and true, approximating the original contour as close as practicable. The final finished surfaces shall match the texture, color and aggregate exposure of the existing concrete surfaces adjoining or proximate to the area where new concrete has been placed. The Contractor shall capture all the waste and water from the finishing operations, and dispose these materials. All materials and/or labor costs resulting from the surface finishing operations, including sedimentation and dewatering controls shall be included in this item of work.
d.Curing . Curing procedures and methods shall comply with the color additive manufacturer’s recommendations and as set forth in Subsection 601.03.8; Curing , of these Specifications, or as otherwise directed by the Engineer. Use of curing compounds is not permitted unless specifically required by the manufacturer of the color additive. 8−187
837.04 METHOD OF MEASUREMENT . “Repairs to Structural Concrete Masonry with Integrally
Colored Concrete or Patching Mortar” will be measured by the number of cubic feet of such materials actually placed in accordance with the Plans and/or as directed by the Engineer. 837.05 BASIS OF PAYMENT . The accepted quantity of “Repairs to Structural Concrete Masonry with Integrally Colored Concrete or Patching Mortar” will be paid for at the contract unit price per cubic foot as listed in the Proposal. The price so-stated shall constitute full and complete compensation for all materials, labor, equipment, tools, forms, scaffolds, wire mesh, anchors and bonding grout, and all incidentals required to finish the work, complete and accepted by the Engineer. Steel reinforcement and dowels shall be paid for under separate items. SECTION 838 SAW CUT IN EXISTING CONCRETE WALLS
838.01 DESCRIPTION . This work consists of saw cutting existing reinforced concrete retaining
walls and/or wingwalls at the locations indicated on the Plans or as directed by the Engineer, all in accordance with these Specifications. 838.02 MATERIALS . Not applicable.
838.03 CONSTRUCTION METHODS . Two separate horizontal sa w cuts, to the limits and depths
as shown on the Plans, are required to be made along each wall face to reduce and control the amount of concrete breakage required and to assure a neat line in the finished work. Copings may be cut transversely into smaller pieces or removed in one piece at the option of the Contractor, as long as the concrete to remain is not damaged during the removal operations. The intentions of the saw cut is to cut existing reinforcements at the saw cut lines. Suitable guidelines and devices must be used to assure cutting along a true line, as shown on the Plans. The type of concrete saw and the method of support to be used will be subject to approval by the Engineer. 838.04 METHOD OF MEASUREMENT . “Saw Cut in Existing Conc rete Walls” will be measured by the number of linear feet actually cut in accordance with the Plans and/or as directed by the Engineer. 838.05 BASIS OF PAYMENT . The accepted quantity of “Saw Cu t in Existing Walls” will be paid for at the contract unit price per linear foot as listed in the Proposal. The price so-stated constitutes full and complete compensation for all labor, materials, and equipment, and all incidentals required to finish the work, complete and accepted by the Engineer.
Source: Rhode Island Standard Specifications (Bluebook), 2024 Edition. Pages 517–521 of 826.