427Surface Finishes for Concrete

2.1 Coatings .

2.1.1 Adhesive Grout and Concrete Paint . Provide coatings in accordance with DMS -8110 , “Coatings for

Concrete.” Match color of coating with Federal Standard 595C color 35630, concrete gray, unless otherwise shown on the plans.

2.1.2 Opaque Sealer . Provide penetrating- type sealer in accordance with DMS -8110 . Match color of coating with

Federal Standard 595C color 35630, concrete gray, unless otherwise shown on the plans.

2.1.3 Silicone -Based Paint . Provide silicone resin emulsion paint (SREP) meeting the requirements of

DMS -8141 , “Paint, Silicon Resin for Concrete.” Match color of coating with Federal Standard 595C color 35630, concrete gray, unless otherwise shown on the plans .

2.1.4 Epoxy Waterproofing. Provide Type X epoxy in accordance with DMS -6100 , “Epoxies and Adhesives,” or

another approved waterproofing epoxy designed to limit the moisture vapor transmission into a concrete or steel surface. Match color of coating with Federal Standard 595C color 35630, concrete gray, unless otherwise shown on the plans.

2.2 Exposed Aggregate Finish. Provide approved aggregates meeting the grading requirements shown on the plans. Provide gravel consisting of predominantly rounded particles unless otherwise shown on the plans.

Use crushed stone when a bush- hammered finish is desired. Provide a concrete surface retardant. Provide clear Type II permanent anti -graffiti coating in accordance with DMS -8111 , “Anti -Graffiti Coatings.”

3.1 Water Blasting . Use equipment capable of supplying a minimum pressure at the nozzle end of 3,000 psi.

3.2 Abrasive Blasting . Use equipment with filters to produce oil -free air and water -free air when dry air is

required.

3.3 Slurry Blasting . Use equipment capable of combining air and abrasives with water to form wet blast media

capable of cleaning and preparing surface without creating dust.

3.4 Spraying . Use equipment with fluid and air pressure regulators and gauges to allow for adjustment to

produce a uniform spray pattern for coating applications.

3.5 Off-the-Form Finish Forms . Use nonstaining, nonporous, high- quality forming materials (e.g., steel or

medium -density and high- density overlaid plywood forms). Use steel or high- density overlaid plywood forms when the same form will be used more than t wice. 590 3.6. Form Liners . Provide form liners capable of producing a patterned finish as shown on the plans. Use form liners that provide a clean release from the concrete surface without pulling or breaking the textured concrete.

4.1 Surface Areas of Finish . “Surface area of finish” designates the areas where the specified surface is to be

applied.

4.1.1 Surface Area I . Surface Area I includes the following:

 surfaces of railing;  exterior vertical faces of fascia beams, slabs, slab spans, arches, and box girders;  the outside bottom surface of fascia beams and girders;  the underside of overhanging slabs to the point of juncture of the supporting beam;  the entire underside of slab spans when shown on the plans;  vertical and underside surfaces of bents and piers;  all surfaces of tie beams, abutments, bridge wingwalls, culvert headwalls and wingwalls, and retaining walls exposed to view after all backfill and embankment are placed; and  all other exposed surfaces shown on the plans to require surface treatment.

4.1.2 Surface Area II . Surface Area II includes surfaces of railing , all wingwalls, and the exterior vertical faces of

slabs.

4.1.3 Surface Area III . Surface Area III includes only the top and roadway faces of all concrete railing and bridge

wingwalls.

4.1.4 Surface Area IV . Surface Area IV includes areas shown on the plans.

4.2 Coatings . Apply the coating specified on the plans.

4.2.1 Preparation . Clean the surface thoroughly before applying a coating by chemical cleaning, if required, and

by blast cleaning. Provide containment that keeps public property, private property, and the environment from being adversely affected by the cleaning and painting operations. Do not discharge washwater into any body of water or conv eyance without TCEQ approval. Collect and properly dispose of any paint or debris dislodged by cleaning operations. 4.2.1.1. Chemical Cleaning . Clean surfaces contaminated with oil, grease, or other contaminants by scrubbing the area with an approved detergent or other concrete cleaning material before blast cleaning. Do not use a solvent that will stain the surface or inhibit coating adhesion. Perform the following test to check for surface contamination of oil type materials .  Spray the surface with a fine mist of potable water.  Examine the area to see if water beads up.  Clean the surface if beading is found. 4.2.1.2. Blast Cleaning . Blast clean the designated surface to remove all surface material (including existing coatings) , curing compound, and other contaminants before applying a specified coating, leaving a lightly etched uniformly textured surface. Use an approved abrasive propelled by oil -free air with or without the addition of potable water, or blast with potable water with or without the addition of an approved abrasive at sufficient pressure to effectively clean and prepare the surface. Maintain the stand- off distance of the nozzle to at most 12 in. from the surface being cleaned when water blasting. 591 Do not damage concrete surface by gouging, spalling, or exposing coarse aggregate by the blasting operation. Blow clean oil- and moisture- free air on all surfaces with sufficient pressure to remove loose particles immediately before application of any coating. Perform the following test to check for surface cleanl iness as directed.  Press a 10- in. long strip of 2- in. wide clear packing tape on the surface by rubbing with moderate pressure.  Grasp the free end of the tape and remove the tape from the surface with a sharp jerk .  Examine the surface of the tape for clinging particles. Continue cleaning the concrete surface until there are no particles clinging to the tape surface for subsequent tests. An additional test that can be used to check the surface for dust is to wipe the surface with a dark cloth and then examine the cloth for discoloration.

4.2.2 Coating Application . Mix coating materials in conformance with the manufacturer’s instructions and

thoroughly enough with a mechanical mixer at a speed that causes the mixture to rotate entirely in the container. Ensure compl ete mixing by probing the container using a stirring device searching for non-dispersed or settled material. Apply coatings once the new concrete has aged at least 28 days , except for the adhesive grout coating. Do not apply coatings when weather conditions will be detrimental to the final surface finish as determined by the Engineer. Do not apply coatings when surface temperature of the concrete exceeds 110°F. Apply coatings on a dry surface . Do not thin material unless approved. Apply when ambient temperature is between 50°F and 10 0°F. Apply coatings to obtain a consistent color , texture , and appearance. Apply concrete paint in two coats for a total maximum application rate of 150 sq. ft. per gallon. Apply opaque sealer in two coats for a total maximum application rate of 200 sq. ft. per gallon. Apply silicone resin paint in two coats at a rate not exceeding 300 sq. ft. per gallon per coat. Wait at least 12 hr. between coats for silicone resin paint. Apply epoxy waterproofing at a maximum application rate of 100 sq. ft . per gallon. For epoxy waterproofing, apply a thin uniform film of mixed epoxy to the substrate using a short nap roller or brush. The epoxy may be sprayed in conformance with the thinning requirements of the manufacturer. No more than 15% reduction is permitted. Repair coatings that exhibit peeling, flaking, or discoloration or have been damaged during construction. Remove defective or damaged coating. Clean and recoat repair area in accordance with this Item. 4.2.2.1. Epoxy Waterproofing. Mix epoxy in conformance with manufacturer’s instructions. Apply the coating on a dry surface at a maxim um application rate of 100 sq. ft . per gallon. Apply a thin uniform film of mixed epoxy to the substrate us ing a short nap roller or brush. The epoxy may be sprayed in conformance with the thinning requirements of the manufacturer. No more than 15% reducti on is permitted. Match the color of the applied coating with the color standard as shown on the plans. Apply when ambient temperature is between 50°F and 100°F. 4.2.2.2. Adhesive Grout . Apply coating on a moistened surface to a uniform minimum thickness of 1/16 in. Apply when ambient temperature is at least 50°F.

4.3 Special Surface Finishes. Submit a work plan to the Engineer for any special finish shown on the plans.

Include in the work plan the type of aggregates, materials, variation of panel or pattern arrangement, dimensions, construction methods, and other features affecting the work as necessary for the “Special Surface Finish” specified.

4.3.1 Blast Finish . Provide surface profile as shown on the plans, or meet the minimum requirements of

Section 427.4.2.1., “Prepar ation.” Construct a 4 × 4-ft. sample panel using the same concrete used in construction of the member to receive the blast finish. Prepare the surface of the sample panel to meet the 592 specified finish, and obtain approval of the sample finish. Use the approved sample panel finish as the standard for surfaces requiring a blast finish.

4.3.2 Slurry Coat Finish. Provide cementitious slurry coat finish to concrete surfaces within 14 days of placing

concrete or later as approved. Water blast surface to moisten surface before application when application of slurry coat occurs more than 14 days after placing concrete. Do not apply slurry coat finish to surfaces receiving another type of coating finish. Submit for approval proposed slurry recipe including cement, latex concrete additive, with or without sand, and other additives before application. The Engineer will direct the level of surface texture the slurry coat will have, whether to include sand, and what fineness of sand is to be used. Tint mixture of slurry as speci fied on the plans and as directed. Maintain consistent slurry throughout project , only modifying recipe to account for color variations noticed as work progresses. Rub in slurry using carborundum stone, stiff bristle brush, or other approved device. Limit thickness of applied slurry to a maximum of 1/16 in. Demonstrate application methods for slurry coat and obtain approval of proposed surface. Apply slurry coat to obtain a tightly adhering cementitious finish to concrete surface. Remove material and reappl y if slurry coat is not tightly adhering or is cracked.

4.3.3 Rub Finish. Provide a finish to the surface by rubbing the surface with a carborundum stone or other approved material. Begin rubbing the surface immediately after forms have been removed. Provide blast

finish or other finish as directed at no additional cost to the Department if rubbing surface is delayed to the point where the surface is dry and unable to be rubbed to produce an acceptable finish. Perform the requirements to obtain the ordinary surfa ce finish specified in Section 420.4.13., “Ordinary Surface Finish,” concurrently with rubbing the surface. Rub concrete- patching areas after the patch material has thoroughly set and blend the patch in with the surrounding area to produce a surface with uniform color and texture where concrete patching is performed. Keep the surface continuously wet after form removal until the rubbing is complete. Rub the surface sufficiently to bring the wetted concrete surface to a paste, producing a smooth, dense surface without pits, form marks, or other irregularities. Do not use cement grout to form the paste on the surface. Stripe the surface using a brush to conceal the rubbing pattern and allow the paste to reset. Wash the concrete with potable water after the pas te has sufficiently set to leave it with a neat and uniform appearance and texture. Apply membrane curing, if required, in accordance with Item 420, “Concrete Substructures,” after rubbing is complete.

4.3.4 Off-the-Form Finish. Provide a finish with minimal surface defects and uniform color and texture by using

non-staining, non- porous, high- quality forming materials. Use the same type of forming materials for like elements for the entire structure. Use mortar -tight forms to prevent leakage and discoloration. Seal joints using compressible gasket material, caulk, or tape, or by other suitable means that are not detrimental to the concrete finish, if necessary. Use one brand and type of form -release agents for all surfaces unless another product produces a similar concrete surface appearance. Do not use barrier -type ( e.g., wax, fuel oil, and carrier oil) release agents. Use form-release agents containing a rust inhibitor on steel forms. Clean rust off steel forms before use. Use plywood that will not cause discoloration of the concrete surface. Direct special attention to consolidation and vibration of the concrete around the form surfaces to minimize bug holes. Modify concrete placement and vibration techniques if surface contains an exces sive amount of bug holes. Remove all forms without interruption once form removal begins to prevent discoloration due to differing form curing times. Do not use membrane curing on surfaces with off -the-form finish. Repair honeycombed and spall areas with l east dimension larger than 2 in. in accordance with the concrete surface repair procedures in Item 420 to obtain an ordinary surface finish as defined in Section 420.4.13., “Ordinary Surface Finish.” Patch honeycombed and spall areas with least dimension greater than 3/4 in. but 593 smaller than 2 in. by filling defect with repair material omitting the chipping operation. Do not patch honeycombed and spall areas with least dimension smaller than 3/4 in. Perform required repairs as soon as forms are removed. Match repair material color and texture with surrounding concrete surfaces. Minimize the area of repair by not smearing the repair material over acceptable concrete surfaces while attempt ing to blend the repair with the surrounding concrete. Cut out form ties at least 1/2 in. below the surface, and patch accordingly. Perform repair work as soon as possible after removing forms so that concrete and repair material s have similar ages. Replace or refurbish the forms when the Engineer determines defective formwork is causing an excessive amount of repair work.

4.3.5 Form Liner Finish. Provide patterned finish as shown on the plans. Do not splice form liner panels in a way that causes a noticeable transition or line between pieces. Wash and clean form liners after each use when the forms can be reused. Replace form liners that have become damaged or worn.

Construct a sample panel for each form liner finish. Approval is required to verify the sample panel meets the requirements shown on the plans and in conformance with s pecifications before beginning work. Upon approval, the sample panel becomes the model panel to which all other work will be compared. Deviation in color, grade, or depth from the model panel is grounds for rejection of the form liner finish. Removal of defective work may be necessary as determined by the Engineer and in accordance with the surface finish requirements in Item 420 to obtain an ordinary surface finish as defined in Section 420.4.13., “Ordinary Surface Finish.” Seal all form liner joints in a manner acceptable to the Engineer to prevent leakage at the surface.

4.3.6 Exposed Aggregate Finish. Provide exposed aggregate finish as shown on the plans. Provide a depth of

finish between 3/8 in. and 1/2 in. unless directed otherwise. Apply a concrete surface retarder that penetrates approximately 1/4 in. into the forms or concrete surface to help achieve the desired finish. Apply two or three coats to wood forms to account for absorption if necessary. Tape or caulk form joints to prevent escape of the retarder during the placing operations. Protect the form surfaces from sun and rain while exposed to the atmosphere. Re- treat form surfaces with retarder if disturbed. Protect adjacent areas of concrete not requiring exposed aggregate finish from the retarder. Remo ve forms 12– 15 hr. after concrete placement but not before concrete has gained sufficient strength to support the self -weight of the member , unless directed otherwise. Expose the aggregate for the finish immediately after form removal. Remove the grout paste covering the aggregate to be exposed by an approved method. Do not loosen the aggregate by the grout removal operation. Maintain required curing on all surfaces except for the time while the aggregate is being exposed. Cure using wet mats or membrane after the aggregate is exposed. Repair defective areas as determined by the Engineer. Re-clean exposed aggregate surfaces by an approved method. Apply a coat of clear Type II permanent anti-graffiti coating to cleaned exposed aggregate surface. Apply anti -graffiti coatings by spray, roller, or brush at the application rates recommended by the manufacturer and in accordance with Item 740, “Graffiti Removal and Anti -Graffiti Coating.”