7-29 Section 706. Structural Concrete Construction
706.01. Description This work consists of constructing concrete portions of bridges, box and slab culverts, headwalls , parapets, wingwalls , retaining walls, and other structures, and providing and installing elec trical grounding systems. 706.02. Materials Provide materials in accordance with the following sections : Curing Materials .................................................................................... 903 Insulating Blankets ................................................................................ 903 Polystyrene Insulation ........................................................................... 903 Steel Reinforcement ............................................................................. 905 Bar Chairs and Wire Ties ...................................................................... 905 Structural Steel ..................................................................................... 906 Miscellaneous Metal Products .............................................................. 908 Geosynthetics ....................................................................................... 910 Water ..................................................................................................... 911 Fiber Joint Filler for Concrete Construction ........................................... 914 Joint Sealants for Concrete Construction .............................................. 914 Conduit ................................................................................................. 918 Electrical Grounding System ................................................................. 918 Concrete, Grades 3500, 3500HP, 4500, 4500HP ............................... 1004 Mortar and Grout ................................................................................. 1005 Provide Grade 3500 concrete for structure concrete placed under water . Provide slump for these tremie applications in accordance with Table 1004-1. Provide Grade 3500 concrete for substructure and subfooting concrete. Provide Grade 3500HP concrete for high- performance substructure concrete. Provide Grade 4500 concrete for superstructure concrete and superstructure concrete, night c asting. Provide Grade 4500HP concrete for high- performance superstructure concrete and high- performance superstructure concrete, night casting. Provide natural aggregate and with no greater than 2.50 % absorption as specified in ASTM C127 for structure concrete. Do not use slag aggregate. Provide expansion joint devices and end plates meeting the requirements of AASHTO M270, Grade 36, or ASTM A588/A588M . Galvanize expansion joint devices and end plates in accordance with section 716. Provide commercial -quality steel floor plate meeting the requirements of ASTM A786/A786M, galvanized in accordance with section 716, for expansion joint MDOT Standard Specifications for Construction Section 706
7-30 cover plates. Provide ASTM F593 (Type 304) stainless steel, flathead
countersunk screws with inserts . Refer to section 1004, Table 1004- 1, and the contract for required minimum flexural and compressive strengths of concrete. Select penetrating water repellant from the Qualified Products List. 706.03. Construction
A.Equipment
1.Placing Equipmen t. Use equipment with capacity and arrangement for placing concrete in accordance with subsection 706.03.H . Make equipment available to the Engineer for inspection, testing, and approval before use. Use a tremie, pump, or other Engineer -approved equipment for placing concrete under water. If placing concrete with a tremie, provide a tremie with a capacity of at least 7 cubic feet and a watertight discharge tube at least 10 inches in diameter . Equip the lower end of the tremie with a valve or suitable device capable of closing tightly while charging and lowering the tremie into position and opening fully in the lowered position. If pumping concrete, provide a pump discharge, pipe, and fittings with an inside diameter of at least 4 inches . Do not use aluminum pipe for conveying or placing concrete.
2.Bridge Deck Finishing Equipment . Use a self -propelled, transverse finishing machine capable of finishing concrete from curb line to curb line or from curb line to bulkhead. Equip bridge deck finishing machines with rotating finishing cyl inder(s), auger(s), drag float, and other structural and mechanical equipment to finish the concrete within the required tolerances. Use a machine or supporting frame to transversely span the cast section and travel in the direction of concrete placement . Mount the machine on wheels operated on longitudinal rails capable of carrying the loads between supports with a deflection no greater than 1⁄16 inch. Mount rail s on adjustable supports that prevent deflection under the machine load. Use rail sections, straight within ⅛ inch per foot, and rail grades that differ from the required screed grade by no more than 1⁄16 inch. Install the rail at a height above the surface allowing hand floating under the rails. Place rail supports over beams unless approved by the Engineer . Design falsework supporting rails in accordance with subsection MDOT Standard Specifications for Construction Section 706
7-31 706.03.C . Use portable, lightweight, or wheeled work bridges capable
of transversely sp anning the cast section to transversely finish machine-finished deck sections. Use a 3-foot, lightweight metal float and a 10 -foot, lightweight, rigid straightedge, each equipped with a suitable handle. Alternative types of vibrating or oscillating screed s may be used if approved by the Engineer.
3.Concrete Saws. Use a self -propelled saw to neatly cut hardened concrete to the line and depth required.
4.Texturing Equipment . Use texturing equipment to produce uniform transverse grooves of the required width, depth, and spacing.
5.Equipment for Applying Penetrating Water -Repellent Material . Apply penetrating water repellent material with low -pressure, 15 to 40 psi, airless -type spray equipment or with long- nap rollers.
6.Equipment Approval . Obtain the Engineer ’s approval for all equipment and tools for placing and finishing of concrete before starting work , including, but not limited to, pumping equipment, air compressors, vibrators, joint -sealing equipment, straightedges, and finishing tools.
B.False Decking . Construct false decking to the limits shown on the plans. Construct false decking capable of supporting all material and debris falling from the deck . Abut false decking pieces to prevent material or debris from falling through. Use a f alse decking system that does not damage beams and meets the approval of the Engineer. Install false decking after erecting structural steel or precast concrete beams or before beginning deck removal, repair, or other bridge construction activities . Do not construct false decking systems over traffic that project below beam bottom flanges . Maintain false decking to prevent hazards to vehicular, pedestrian, or waterway traffic . Remove material or debris on the flooring outside the fascia at least once a day. Leave false decking in place until completion of construction activity, as directed by the Engineer. For bridges over waterways, barges may be used in the waterway in place of constructing a false decking system . Position the barge in the waterway after erecting the structural steel or precast concrete beams or before beginning deck removal, deck repair, or bridge construction activities . Maintain the barge to prevent hazards or impediments to waterway traffic . Provide a barge large enough to support material and debris falling from the deck . Leave the barge in place until the bridge deck MDOT Standard Specifications for Construction Section 706
7-32 over the waterway is cast . If the Engineer determines that the barge is
ineffective in preventing falling material and debris from entering the waterway, replace it with a conventional false decking system at no additional cost to the Department.
C.Falsework. Design, const ruct, place, and remove temporary supports required for constructing the permanent structure. Weld f alsework supports in accordance with subsections 707.03.E.7.b, c, d, and g. Do not weld to the structural steel or use mechanical fasteners that damage the structural steel or coatings. Submit working drawings and design calculations for falsework if required by the contract . Submit working drawings and calculations in accordance with subsection 104.02 a minimum of 14 days prior to beginning installation. The working drawings and design calculations must be sealed by a Professional Engineer licensed in the State of Michigan. Do not place concrete prior to securing the Engineer ’s approval of the working drawings and calculations. Correct settle ment in the falsework during loading.
D.Forming
1.General . Construct forms true to the lines shown on the plans . Construct mortar -tight forms with net sections capable of withstanding impacts during placement and supporting the weight of concrete through curing. Use falsework for forms in accordance with subsection 706.03.C. Deck forms or supports are not allowed to protrude above the top of haunch es or above the bottom of the deck .
2.Vertical Clearance. The Department defines minimum vertical clearance as the minimum vertical distance from any point on the roadbed surface, including 24 inches either side of the roadbed, to the low beam . Over active roadbeds, m aintain formwork above the bottom of beams . Obtain the Engineer ’s approval if form work must extend below the bottom of beams . Provide and place advance-warning signs at locations directed by the Engineer before changing the existing structure vertical clearance. Provide 14 days for the Engineer to determine l ocations for the advance warning signs.
3.Removable Forms
a.Type A Surface. Type A surfaces are exposed surfaces of piers, abutments, wingwalls, retaining walls and the outside faces of MDOT Standard Specifications for Construction Section 706
7-33 girders, T beams, slabs, columns, brackets, curbs, headwalls,
barriers, ra ilings, arch rings, spandrel walls, and parapets. Use metal forms or 5-ply structural grade western fir plywood for face-forming material . If the grain of three plies of the plywood runs perpendicular to the studs, the 25⁄32-inch thickness meet s 1-inch nom inal thickness. The Engineer will allow dressed shiplap or square-edged lumber, sized four sides, at least ¾ inch thick, and covered by form lining instead of structural plywood for form lumber . Use metal, composition, or plywood form lining for shiplap or square-edged lumber . Use composition or plywood lining at least ¼ inch thick. The Engineer will evaluate the sizing, spacing, and dimensions of metal, composition, or special plywood forms and may allow continued use based on performance. The Engineer may modify the requirements for pattern and minimum lumber thickness for curved Type A surfaces . The inside faces of forms for Type A surfaces must be free of holes, irregularities, and unevenness.
b.Type B Surface. Type B surfaces are formed concrete surfaces that will not be exposed in the finished work , the bottoms of floor slabs and sidewalk , the sides of interior beams and girder s, backwalls above the bridge seat , and exposed surfaces not included in Type A surfaces. Use metal forms or face-forming material at least ¾ inch thick for Type B surfaces. Material allowed for Type A surfaces may be used for Type B surfaces, except do not use square-edge d lumber for forming horizontal surfaces . Form lining is not required for shiplap and square-edge d lumber.
c.Type A and B Surfaces. Do not use forms and face-form material with defects for Type A or Type B surfaces. For Type A surfaces, space studs no greater than 12 inches center -to-center . For Type B surfaces, space studs no greater than 24 inches center -to-center . Provide nominal 2 by 6-inch or 4 by 4-inch sections, except that nominal 2 by 4-inch studs are allowed for pour heights not exceeding 3½ feet. Cap studs with a straight top plate at least the size of the Engineer -approved studs. Scab all joints in plates 4 feet each way to provide continuity. MDOT Standard Specifications for Construction Section 706
7-34 Constructed forms must remain true to shape. Countersink bolts
and rivet heads on the inside face of the forms. Design clamps, pins, or other connecting devices to hold forms rigidly together and allow removal without damage to the concrete. Do not use metal forms that do not present a smooth surface or that do not line up properly . Maintain metal forms free of rust, grease, and other material that may discolor concrete. Scab wales to prevent distortion during concrete placement and curing . Place a row of wales within 6 inches of the bottom of each pour, unless studs ext end below the bottom of the pour secured by wales fastened to rods in the previous pour.
d.Construction . Brace forms to prevent movement during concrete placement . Do not use mechanical or adhesive methods to secure forms to concrete bridge decks or pavement s that will be exposed in the completed work . Finish corners square without moldings . For exposed concrete faces, saw the form edges at corners square and straight and place them to form a tight fit . Form chamfered corners with dimensions measured on the s ides. For Type A surfaces, arrange the forms to present a neat geometric pattern of form marks . Do not offset or shift patterns . Construct forms to allow removal without damaging concrete.
e.Ties and Spreaders. Do not use wire ties and pipe spreaders. After removing forms, remove the ends of metal appliances inside the forms to maintain correct alignment . Remove ends to a depth of at least 1 inch from the surface of the concrete without creating an opening greater than 1½ inches in diameter . Remove metal or wooden spreaders that are separate from form ties during concrete placement.
f.Form Surface Treatment . Treat the inside of forms with a release agent that will not discolor or adversely affect the concrete. Do not allow the release agent to c ontact steel reinforcement or existing concrete or steel surfaces.
4.Permanent Metal Deck Forms
a.Materials and Fabrication . Provide corrugated forms and supports fabricated from steel sheet conforming to ASTM A653/A653M and galvanized to a G210 coating designation. Provide fasteners galvanized in accordance with AASHTO M232 . Fabricate permanent metal deck forms, supports, and accessories in accordance with section 707. MDOT Standard Specifications for Construction Section 706
7-35 b. Design . Verify beam dimensions befor e fabricating permanent
metal deck forms. Design forms, form supports, and attachments to carry a 50-pound-per -square-foot construction load, all dead loads, and resultant horizontal loads due to forming of cantilever overhangs . Consider the span length to be the clear span of the form plus 2 inches, measured parallel to the form flutes . Consider the full-deck slab thickness shown on the plans to be above the corrugations . Design forms for a maximum d eflection of ¼ inch or 1⁄180 of the form span length, whichever is less . Do not use form camber to compensate for deflection greater than the limits specified. Use unit working stresses no greater than 0.725 of the specified yield strength of the steel, or 36,000 pounds per square inch , whiche ver is less. Submit working drawings and calculations for permanent metal deck forms, supports , and connections in accordance with subsection 104.02 a minimum of 14 days prior to beginning installation. The working drawings and design calculations must be sealed by a Professional Engineer licensed in the State of Michigan.
c.Construction . Do not use metal forms below longitudinal or transverse open joints or expansion-type joints. Do not allow form sheets to rest directly on beam flanges . Center each sheet in the bay and provide a bearing length of at least 1 inch at each end. Attach sheets promptly to avoid hazards that may result from lateral movement or sudden uplift of the forms . Provide safety stops where necessary. Make attachments using bolts , clips, or other Department -approved methods . Attach forms to supports using sheet metal screws, or other Department -approved fasteners, from the top side where practical . Do not weld forms or accessories to structural steel . Size support straps such that welds terminate a minimum of ¼ inch from the edge of the strap. Do not flame cut metal deck forms or supports . Repair of galvanized areas at welds or unbolted edges after shearing or punching is not required. Field drill ¼ -inch-diameter weep holes at spacing no greater than 12 inches along transverse and longitudinal construction joints. Place and secure polystyrene in corrugations to prevent displacement during concrete placement. MDOT Standard Specifications for Construction Section 706
7-36 Do not fill corrugations with concrete.
5.Form Liners for Aesthetic Textu ring of Concrete . Use smooth, custom formed elastomeric or multi -use, acrylonitrile butadiene styrene (ABS) plastic form liners to produce the concrete textures as required in the contract . Single-use, polystyrene, or similar plastic liners are prohibited. Submit shop drawings to the Engineer for approval a minimum of 14 days prior to placing form liners . The s hop drawings must detail the form liner pattern and geometry , show the complete pattern layout for the entire limits of textured concrete as required in the contract, and indicate where each of the patterns begin and end. Configure the liner so the contours do not cause the concrete to be locked into the liner . Use form release agents that are compatible with the form liners . Provide written certifica tion from the manufacturer that the form release agent s are compatible and non-reacting and non-staining. If form liners are required by the contract, use a single form release agent for the entire project , including formed surfaces not required to be text ured.
a.Test Sections. Construct a test section for each unique texturing pattern and application of pattern before constructing textured portions of permanent concrete . Test sections must demonstrate the quality of the textured concrete, including the concrete mix design, quality of forming, joint control, consolidation technique, and fully textured corners . Obtain the Engineer ’s approval for the location of the test sections. If the Engineer determines that a test section is not satisfac tory, adjust construction techniques and cast additional test section s until approval from the Engineer has been obtained. The cost of any necessary additional test sections will be borne by the Contractor . Approved test sections will be used by the Engineer as a measure of the quality and finish of the permanent textured concrete.
b.Placing Forms . Do not place form -liner horizontal splices within the textured area. Carefully match vertical splices. Visible seams or conspicuous form marks are not allowed. Bevel the top and bottom edge of the form liner at a 45 degree angle to produce a ¾-inch bevel where pattern ends . Thoroughly clean form liners and cant strips according to the manufacturer ’s recommendations and to the satisfaction of the Engineer prior to each reuse. MDOT Standard Specifications for Construction Section 706
7-37 Handle forms and form liners according to the manufacturer ’s
recommendations for storage, fastening liners to the forms, stripping the lined forms from the concrete, and cleaning and reconditioning liners. Damage or wear that affects the finished appearance of the concrete will be cause for rejection and replacement of the liner . All costs associated with replacement of damaged or worn liners will be borne by the Contractor. Apply release agent according to the manufacturer ’s recommendations . Remove excess release agent to prevent staining of the concrete surface. Locate form ties at high point s of the texturing pattern so they will be in the recess of the concrete. Use form ties designed so that all material can be disengaged and removed without spalling or damaging the concrete. Finish form tie holes according to subsection 706.03.R.1.
c.Repairs. Repair or replace textured concrete at no additional cost to the Department that, in the opinion of the Engineer, does not meet the qu ality and finish of the test section.
E.Steel Reinforcement
1.Storage and Protection . Store steel reinforcement on platforms, skids, or other supports . Store steel reinforcement neatly and clearly marked to facilitate inspection. Locate storage sites at water crossing locations above the high water elevation shown on the plans . Store epoxy -coated bars on padded wood or steel cribbing and cover to prevent exposure to ultraviolet rays.
2.Handling of Epoxy -Coated Reinforcement . Use systems with padded contact areas for handling coated bars . Pad bundling bands or use other banding to prevent damage to the coating. Lift bundles of coated bars with a strongback, spreader bar, multiple supports, or platform bridges to prevent bar -to-bar abrasion. Do not drop or drag the bars or bundles.
3.Field Bending . Do not bend reinforcing bars in the field unless otherwise shown on the plans or to correct minor errors or omissions in shop bending. Perform field bending cold. Make field bends in accordance with subsection 905.03.A for shop bends . Repair damaged epoxy coating in accordance with subsection 706.03.E.8.
4.Placing and Fastening . Accurately place and firmly secure steel reinforcement prior to concrete placement . Steel reinforcement must MDOT Standard Specifications for Construction Section 706
7-38 be free of dirt , excessive rust, loose mill scale, and other deleterious
material . Bar spacing must not vary more than one-sixth of the spacing shown on the plans, except as needed to allow placing anchor bolts and position dowels . Do not exceed the bar spacing shown on t he plans . Use wire ties to secure all bar intersections for the top mat . Use wire ties to secure all bar intersections for other mats where the product of the length and width of bar intersection spacing exceeds 120 square inches . If the product of the length and the width of spacing does not exceed 120 square inches, tie alternat ing intersections . Do not weld to steel reinforcement . Tie bar laps within 3 inches of each end of the lap. For all reinforcement except for deck reinforcement, provide a clear distance from the reinforcement to the concrete surface at least equal to the dimensions shown on the plans but no more than 25% greater than the dimension. For deck reinforcement, do not vary the distance from the top transverse reinforcement to the bottom of the concrete slab by more than ⅜ inch from the dimensions shown on the plans . Provide concrete clear cover over the top transverse reinforcement at least equal to the dimensions shown on the plans. Maintain the required reinforcement distances from forms using stays, ties, hangers, bar chairs, or other Department -approved supports, except that in bridge superstructures , use bar chairs only. If bar chairs are used, they must be plastic or coated metal with a bearing area that prevents penetration into forming material . Use commercial -grade concrete brick only in footings. For bridge decks, place bar chairs parallel to the beam, spaced with the lines of supports meas ured from center -to-center, at the ¼ -point and ¾ -point for beam spacing less than 9 feet, and at the 1⁄6 point, ½ point, and 5⁄6 point for beam spacing 9 feet or greater. Use additional bar chairs outside the fascia beam to support reinforcing steel along and near the fascia. On concrete box beam bridges without slab ties, use bar chairs along the longitudinal centerline of each beam . Support the upper layer of reinforc ement directly over the supports for the lower layer of reinforcement with rows of Depart ment -approved continuous steel bar supports consisting of at least three longitudinal wires. Tie the upper layer of reinforcing steel to the structural steel, stud shear developers, or other structural components at intervals no greater than 5 feet along e ach beam or girder . Use two loops of 16 gauge tie wire for tie-downs . Tie coated reinforcement with coated tie wire to prevent wire from damaging the coating. MDOT Standard Specifications for Construction Section 706
7-39 Cover epoxy -coated reinforcement if the concrete for the element is
not cast within 2 months from the time of placing the epoxy -coated reinforcement . Use a cover that will prevent exposure to ultraviolet rays.
5.Splicing. Do not splice bars unless otherwise shown on the plans.
6.Lapping . Lap bars at locations shown on the plans . Do not eliminate or move laps from the locations shown on the plans without approval by the Engineer.
7.Cutting Reinforcement . Saw or shear bars when cutting is permitted. Do not flame cut reinforcing bars.
8.Repair of Epoxy Coating . Repair coating damaged by bending, sawing, shearing, or damaged during shipping, unloading, storage, installation, or handling on the project. Patch sawed or sheared ends and visible defects in accordance with ASTM A775/A775M . Use a patching or repair material selected from the Qualified Products List . Clean areas requiring patching by removing surface contaminants and damaged coating. Roughen the area requiring patching before applying patching material . Remove rust by dry blast cleaning or power tool cleaning immediately before applying patching material. Immediately treat bars in accordance with the patching material manufacturer ’s recommendations and before oxidation occurs . Overlap patching material onto the original coating by 2 inches or as recommended by the manufacturer . Provide at least 8 mils of dry film thickness on the patched areas . Replace bars with 5% or more damaged area in a 12- inch bar length. Coat mechanical splices after splice installation in the same manner as required for sawed or sheared ends .
F.Placing Galvanized Metal Pipe Sleeves. Place galvanized metal pipe sleeves in the bridge to carry utility company facilities across the bridge. The utility company will provide pipe sleeve s at the bridge site at no cost to the Contractor . Notify the utility company at least 7 days before the sleeves are needed. If the contract requires the utility company to install conduit or ducts in the structure, notify the utility company at least 7 days before the utility company is required to install conduit or ducts . The Department will not allow additional compensation for costs associated with delays caused by utility company operations.
G.Placing Conduit . Align the conduit, tightly fit the joints, and firmly secure conduit prior to concrete placement . Assemble and protect sleeve expansion joints in the superstructure to allow movement after concrete MDOT Standard Specifications for Construction Section 706
7-40 encasement . Place concrete encasement after the Engineer approves the
alignment of and connection to the conduit . Swab the conduit for the entire length immediately after casting encasement to remove concrete materials .
H.Placing Concrete
1.General . Prepare and test work progress specimens as necessary in accordance with section 1002 . Obtain the Engineer ’s written approval of forms, bracing, reinforcing steel, and preparations for casting concrete before beginning concrete placement operations . Before placing c oncrete, clean forms, piling, and reinforcing steel and remove sawdust, chips, and other debris from the form interior . Concrete placed without the Engineer ’s approval may be rejected and required to be removed. Remove struts, stays, and braces to hold forms in the correct shape and alignment when the concrete elevation renders them unnecessary. Place concrete to avoid material segregation and reinforcement displacement. Complete each pour in a continuous operatio n with no interruption longer than 45 minutes, except concrete subfootings . Place and consolidate each layer before initial set of the previous layer. For concrete subfootings, the Contractor may place vertical construction joints within the subfooting for a substructure unit. Do not place additional concrete on finished reinforced substructure concrete until the substructure concrete cures for at least 3 days and attains at least 70% of its required minimum 28-day flexural or compressive design strength. Do not use mechanical attachments to support forms until substructure concrete attains at least 70% of its required minimum 28-day flexural or compressive strength. The Engineer may lower the concrete strength required for attaching forms after reviewing calculations performed by a P rofessional Engineer, licensed in the State of Michigan, showing that forces due to imposed loads will not exceed the capacity of the concrete section based on 70 % of the concrete strength at the time the loads are applied. Do not pour deck concrete until diaphragm concrete attains a compressive strength of 70 % of its required minimum 28 -day flexural or compressive strength . MDOT Standard Specifications for Construction Section 706
7-41 Regulate concrete placement so pressure caused by wet concrete
does not exceed the pressure us ed in designing the forms. Place the concrete in the forms in layers of suitable thickness as close to the final position as possible. In pier caps and wall sections, place layers no greater than 12 inches thick . The Engineer may modify the layer thickness requirements for wall sections depending on the steel reinforcement spacing. Place subfooting and tremie concrete to the full depth of the section. Place footing concrete and column concrete in layers no greater than 36 inches thick. For concrete placed by pumping, dispose of water -cement slurry used to lubricate the discharge pipe outside the forms. Other than subfootings and tremie seals , place and vibrate substructure concrete in the dry. Do not allow superstructure concrete to free fall more than 12 inches to the top of reinforcing steel . Do not allow concrete to free fall more than 5 feet for other structural applications . If concrete must drop more than 5 feet, place concrete through Department -approved pipes or tremie tubes at least 6 inches in diameter and arranged to avoid concrete segregation. If reinforcing bar spacing prevents the use of a 6-inch tube, loosen the bar ties and spread the bars enough to allow the use of the tremie tube or chute. Reposition and re-tie reinforcing bars before covering with concrete. Use mechanical, high-frequency internal vibrators approved by the Engineer and capable of visibly and effectively consolidating the concrete mixture for a radius of at least 18 inches from the tip of the vibrator . If using epoxy -coated or other coated reinforcement, use a vibrator with a rubber -coated head. The Engineer may allow concrete consolidation using hand methods if the use of vibratory equipment is not possible. Use vibrators to consolidate incoming concrete within 15 minutes of placement . Manipulate vibrators to work the concrete around the reinforcement and embedded fixtures into corners and angles of forms. Vibrate freshly placed concrete at the point of placement . Thoroughly consolidate the concrete, but do not cause segregation. Move vibrators to prevent forming localized areas of grout . Uniformly space the points of vibration no greater than twice the radius of the visibly effe ctive vibration area. Do not hold vibrators against forms or MDOT Standard Specifications for Construction Section 706
7-42 reinforcing steel, and do not use them for flowing or spreading
concrete. Do not disturb partially hardened concrete. Do not disturb forms or projecting reinforcement after the initial set of the concrete. Maintain forms, reinforcing steel, and placing equipment clean and free of hardened concrete. Discharge water used to flush placing equipment away from concrete and forms. If concreting operations extend into the night, illuminate the work to make operations clearly visible for inspection. Do not form or cast sidewalk, brush block , or barrier pours until the deck concrete attains its required minimum 7 -day flexural or compressive strength and after completion of the 7-day continuous wet cure. Do not place heavy equipment on the deck until the deck concrete attains its required minimum 28-day flexural or compressive strength and after completion of the 7- day continuous wet cure.
2.Hot Weather Limitations . Place bridge deck concrete when the rate of evaporation at the site is less than 0.20 psf per hour in accordance with Figure 706-1 . Cast concrete only when the temperature of the concrete being placed is below 90°F. Supply and use Engineer -approved equipment for determining the relative hum idity and wind velocity on the project.
3.Placing Concrete u nder Water . Place concrete under water if shown on the plans . Place concrete under water in a compact mass in the final position using a tremie tube or by pumping. Equip the tremie tube so the bottom end closes if concrete does not encase the pipe. Do not use bottom dump buckets . Maintain still water at the point of placement , and provide tight forms . Do not disturb the concrete after placement . Support the tremie tube to allow free movement of the discharge end over the entire work surface and to allow rapid raising or lowering to adjust the concrete flow . Place the concrete full depth in one continuous operation, starting from one end of the cofferdam . Always keep the tremie tube in the freshly placed concrete; withdraw the tremie tube only upon completion of each pour or as required due to foundation piling or cofferdam bracing. MDOT Standard Specifications for Construction Section 706 7-43 Figure 706 -1: Surface Evaporation for Concrete Estimate the evaporation rate in accordance with the following:
a.Enter the air temperature, measured from 4 to 6 feet above the evaporating surface, on the windward side and shielded from the sun;
b.Move up to the line corresponding to the relative humidity;
c.Move right to the line corresponding to the concrete temperature;
d.Move down to the line corresponding to the wind velocity, measured from 18 inches above the evaporating surface;
e.Read the evaporation rate on the scale to the left of this point. MDOT Standard Specifications for Construction Section 706
7-44 After withdrawing the tremie tube, recharge it with concrete above
water, lower it to the new position, and set the discharge end into freshly placed concrete. During placing operations, maintain the tremie tube full to the bottom of the hopper . After dumping a batch into the hopper, induce the flow of concrete by raising the discharge end of the tremie tube slightly . Do not remove the end of the tremie tube from the concrete. Remove laitance or other deleterious material without damaging the concrete. Place concrete to at least the elevation of the top of tremie seals but no more than 6 inches above the seals . Remove excess concrete. Dewater cofferdams after the tremie concrete has been placed and has attained at least 50% of its required minimum 28-day com pressive strength or after test beams cured in water on top of the tremie concrete break with a flexural strength of at least 325 psi. These strength requirements do not reliev e the Contractor of responsibility for failure of any part of the cofferdam.
I.Nighttime Casting of Superstructure Concrete
1.Construction Methods . Begin work no earlier than 1 hour after sunset or as approved by the Engineer . Complete placement of concrete no later than 1 hour prior to sunrise or as approved by the Engineer . Use the sunset and sunrise times published by the National Weather Service for the proposed date of night casting or the time determined by the Engineer . Coordinate nighttime deck pours with the Engineer to allow scheduling of inspection. Comply with the deck pouring sequence and curing requirements shown on the plans . If approved by the Engineer, the Contractor may consecutively pour areas shown on the plans for simultaneous pour, the same night, using retarder in the first pour to prevent initial set until completion of the second pour . Submit any changes to the pour sequence to the Engineer for approval a minimum of 7 days prior to placing concrete.
2.Lighting Requirements . Use light sources to achieve a minimum average intensity of 10 foot-candles over the entire work area, including the concrete testing area. Submit the deck lighting scheme to the Engineer for approval . Provide a lighting alignment that does not interfere with or impede traffic on open roadways . Refer to subsection 812.03.H for additional lighting requirements for night work. MDOT Standard Specifications for Construction Section 706
7-45 J. Cold Weather Precautions . Protect concrete to prevent damage from
cold weather . Remove and replace frozen concrete or concrete damaged by cold weather at no additional cost to the Department. If the National Weather Service forecasts that air temperatures will remain below 50°F but above 40°F, apply ordinary protection requirements to protect concrete. If the National Weather Service forecasts air temperatures below 40°F during the curing period, apply low -temperature protection requirements to protect concrete. Cure concrete in accordance with subsection 706.03.N.1, except that only one application of curing compound is required.
1.Ordinary Protection . Ordinary protect ion consists of using tarpaulins, straw covering, or other Engineer -approved methods to protect concrete. If the prevailing temperatures will produce concrete temperature less than 45°F, raise the concrete temperature in accordance with subsection 1001.03. E.5. Seal keyways, anchor bolt wells, or other depressions on exposed horizontal surfaces against water intrusion. If approved by the Engineer, protect footings by completely submerging them under water inside the cofferdam area 2 hours after placement . After submersion, maintain water level necessary to cover the concrete and keep ice from contacting the concrete.
2.Low-Temperature Protection . Low-temperature protection consists of using insulated forms or heating and housing to protect concrete. Place concrete in the forms at temperatures specified in subsection 1001.03.E.5. Maintain concrete at a temperature of at least 45 °F.
a.Insulated Forms -Substructure Concrete . Apply blanket insulation tightly against the forms and fasten securely . Insulate corners and edges . If placing concrete against previously cast concrete, extend the blanket insulation at least 14 inches and hold in place against the previously cast concrete. Patch or cover tears and holes in the blanket. Cut polystyrene insulation to fit snugly between wood form studs and fasten securely . For steel forms, fit the insulation boards between the ribs and hold in place wit h adhesive or Department -approved fasteners. Provide insulating blankets or polystyrene insulation meeting the minimum thickness or the minimum R values specified in Table 706-1. MDOT Standard Specifications for Construction Section 706
7-46 Table 706- 1:
Minimum Insulation Requirements Thickness of Pour (inch) Unline d Steel Forms Wood- Lined Steel or Wood Forms Thickness (inch) R Value Thickness (inch) R Value <12 2 7.0 2 5.25 12–24 2 7.0 1.5 5.25 >24 1.5 5.25 1 4.0 Clean ice, snow, and frost from forms when placing concrete . Place substructure concrete when the air temperature is above 35°F, unless the form interiors, metal surfaces , and adjacent concrete surfaces are preheated to at least 35°F . Use only gas-fired burners if heating by direct flame. Place substructure concrete in insulated forms only when the air temperature is above 15°F, except that the Contractor may place subfootings, footings, and CIP concrete piles if the air temperature is above 0°F . Wrap exposed portions of CIP concrete piles with insulating blankets or protect them with straw. Cover the top of pours with insulating blankets . Cover inaccessible areas around protruding reinforcing bars with straw . Cover the tops of insulated pours, including the insulation, with tarpaulins or other Department -approved material. Leave insulated forms in place until the concrete attains at least 50% of the required minimum 28-day flexural or compressive strength and for at least 5 days after final concrete placement in individual units. Unless otherwise directed by the Engineer, do not loosen forms to lower temperatures . Remove blankets or straw from the tops of footings no earlier than the third day after casting to allow forming subsequent portions of the unit . Obtain the Engineer ’s approval before loosening forms or removing the top c overing. If the outside air temperature reaches 0°F or below, or the National Weather Service forecasts air temperatures 0°F or below for the next 24 hours, do not remove forms for 8 days after casting unless otherwise directed by the Engineer and only if the air temperature is between 0°F and 32°F and the temperature difference between the air and the concrete surface is no greater than 30°F . If possible, remove forms at midday.
b.Insulated Forms -Superstructure Concrete. If the National Weather Service forec asts air temperatures below 20°F during the MDOT Standard Specifications for Construction Section 706
7-47 curing period, provide material and heating equipment on the
project to protect f orms and concrete. Do not begin placing superstructure concrete if the air temperature is below 35°F. Do not place superstructure c oncrete if the air temperature is below 40°F unless form interiors, metal surfaces, and the adjacent concrete surfaces are preheated to at least 40°F . Use only gas-fired burners if heating by direct flame. Insulating the bottom of deck forms is not require d. If the National Weather Service forecasts air temperatures below 40°F for more than 8 consecutive hours during the curing period, protect the top of the freshly placed concrete as soon as possible to maintain a concrete temperature of at least 45 °F. Use tightly joined insulating blankets or polystyrene insulation and insulate in accordance with Table 706-1. Hang tarpaulins or other Department -approved material from the top of the curb to enclose the entire protected section. If the temperature falls below 15°F during the curing period, circulate heated air under the enclosed superstructure section. Maintain circulation for the remainder of the protection period required for concrete protected by heating and housing.
c.Heating and Housing . Before placing concrete in forms, provide enclosures for concrete sections being placed to maintain the specified temperatures within the enclosure. Arrange enclosures to allow removal of forms and finishing of concrete surfaces without interrupting heating. Provide uniform forced air or radiant heat in the enclosure. Vent the heating system to prevent exposure to carbon dioxide exhaust gases during concrete placement and curing. Before placing concrete, preheat reinforcing steel and form surfaces to temperatures from 40 to 75°F. During and after concrete pl acement, operate the heating system to maintain an air temperature inside the enclosure from 40 to 75°F. Maintain the temperature inside the enclosure until the concrete attains at least 50% of its required minimum 28-day flexural or compressive strength. At the end of the heating period, decrease the temperature to the outside air temperature at a rate no greater than 15°F per 12 hours . Allow the concrete surface to dry during the cooling period. Remove the enclosure. MDOT Standard Specifications for Construction Section 706
7-48 In case of a heating system failure, provide emergency heaters for
use within 1 hour. Place and operate heaters and provide for moisture, as directed by the Engineer.
K.Construction and Expansion Joints . Construct joints in concrete structures where shown on the plans . Clean laitance and other deleterious material from the contact concrete surface in place, and wet surfaces before placing new concrete. Finis h face edges of joints to the line and elevation shown on the plans . Finish joint surfaces that provide expansion in the plane of the joint within ⅛ inch of a true plane. Form keys within reasonable tolerances using suitable material.
1.Sealer . Use poured joint sealers of the type required by the contract . Handle hot -poured joint sealer material in accordance with subsection 602.03.S.
2.Fiber Joint Filler . Shape premolded expansion joint filler to fit adjacent concrete. Hold premolded expansion joint filler in place to prevent formation of concrete fins under or between expansion joint filler and to prevent the joint filler from being dislodged during concrete placement .
3.Joint Seals. For concrete, install seals as shown on the plans.
a.Sawing Construction Joints . Saw the joint groove at each transverse construction joint, as shown on the plans . Provide a joint groove symmetrical about the construction joint.
b.Expansion Joints . Construct expansion joints as shown on the plans and symmetrical about the filler centerline.
c.Cleaning after Sawing . Immediately after sawing, remove deleterious material from sawed joints.
d.Patching Transverse Joints. Inspect and repair transverse joints in accordance with subsection 602.03.P .
e.Installing Seals . Install the top of the seal ¼ inch below the surface of the deck.
4.Expansion Joint Devices. From the approved ex pansion joint devices shown in the contract, s elect joint devices for each location that are suitable to accommodate the total movement shown in the contract . Inform the Engineer of the select ed expansion joint device. Submit complete working drawings of all details of fabrication of the expansion joint device in accordance with subsection 104.02. This requirement is waived for expansion joint devices for which a set of MDOT Standard Specifications for Construction Section 706
7-49 standard installation details has been approved. Standard installation
details can be obtained from the Engineer. Fabricate the expansion joint to conform to the contour of the bridge deck accounting for raised sidewalks, brush blocks , and barriers as shown in the contract. Install expansion joint devices in accordance with the c ontract and as shown on the approved working drawings . Set the top of the expansion joint device ¼ to ⅜ inch below the top of the concrete slab or pavement . Tie deck -reinforcing steel -to-steel frame anchors to the maximum extent practicable without damagi ng galvanized or epoxy coatings . Clean expansion joint device and install the gland in one continuous piece in accordance with the manufacturer ’s recommendations . If splicing of the gland is required and approved by the Engineer, use a trained representative of the joint manufacturer to perform splicing. Remove shipping bolts prior to placement of concrete. Weld in accordance with subsections 707.03. E.7.b, d, and f .
5.Expansion Joint Device Covers. Install plate covers as shown in the contract . Cast curb s and sidewalks with sliding plates in place to ensure proper alignment of inserts and screws . Apply bond breaker to sliding plates before installation. Form concrete recess areas in sidewalks to receive sliding plates and grind to provide smooth surface . Tool or grind concrete edges to a ¼ inch radius. Apply one coat of epoxy resin adhesive to allow bent sliding plate to move freely without friction. Ensure that no adhesive contacts the expansion joint device or gland. Remove foreign particles before installing plates . Install plates to position the anchors on the high side of longitudinal sidewalk grade . Repair damage to galvanized surfaces in accordance with section 716.
L.Placing Anchor Bolts and Position Dowels in Concrete . Set anchor bolts and position dowels in the forms using a template prior to placing concrete. If shown o n the plans, the Contractor may drill holes in hardened concrete and utilize adhesive anchors or mechanical expansion anchors in accordance with subsections 712.03.J and 712.03.K at no additional cost to the Department. Finish the surface around anchor bolts or position dowels in accordance with subsection 706.03.M.2. MDOT Standard Specifications for Construction Section 706
7-50 M. Finishing Plastic Concrete. Do not over -vibrate or over -finish the
completed surface. If approved by the Engineer, apply water to the concrete surface with a fog sprayer to aid finishing. After finishing, texture sidewalks and curbs in a transverse direction with a broom to produce uniform, narrow grooves no greater than ⅛ inch deep. Texture the final deck surface in accordance with subsection 706.03.M.3.
1.Machine Finishing . Use a self -propelled transverse finishing machine to strike off and finish concrete surfaces subject to vehicular traffic . To accommoda te the type of finishing machine used, the Engineer may authorize elimination of longitudinal construction joints shown on the plans. Immediately before placing concrete, operate the finishing machine over the full length and width of the bridge segment t o be placed and adjacent segments if a pour sequence is required. Perform the test run with the screed adjusted to the finishing position. While operating the finishing machine, check the screed for deflection and adjustment . Measure and record the depth of the reinforcement below the screed, the controlling dimensions of deck reinforcement, and the forms . Make necessary corrections during the test run. Upon completion and documentation of the test run, do not make adjustments to the finishing machine or rails unless approved by the Engineer . When finishing concrete surfaces, complete screed passes with sufficient concrete material along the leading edge to ensure filling low spots . Leave the surface at the required grade and free of water and laitance after the final pass of the screed. Remove deleterious material from the gutters where the Engineer allows final hand finishing. As soon as practical, place the work bridge behind the finishing machine. While concrete remains plastic, test the slab surface for trueness with a 10-foot straightedge or other Engineer -approved method. Finish the surface to the required grade and cross section. Without damaging concrete, c ompletely remov e rail supports or partial ly remov e so no portion remains less than 3 inches below finished concrete. Fill the resulting holes with concrete, consolidate, and finish flush with the deck surface before the deck concrete hardens.
2.Hand Floated Surface Finish . Provide a floated surface finish on areas not requiring machine finishing, such as bridge seats, sidewalks, areas of bridge decks under sidewalks, and similar MDOT Standard Specifications for Construction Section 706
7-51 surfaces . Finish by striking off the concrete surface with a screed set
to the required cross section. Vibrating or oscillating screed s may be used if approved by the Engineer. Provide a movable screed on guides set to the required elevation with allowance for camber if required. After striking -off, finish the surface with a wood or magnesium float. Broom finish the concrete surface under elastomeric bearings.
3.Texturing . Groove the final deck surface as soon as deck concrete can maintain a texture. Construct grooves perpendicular to the centerline. Form grooves in plastic concrete without causing edges to slump or surface tearing. End grooving 12 to 16 inches from sidewalk or barrier edges . Do not groove within 3 to 6 inches of expansion or contraction joints or the end of the slab. Space grooves on ½ -inch centers, ⅛ inch wide, and ⅛ inch deep. Random spacing is permitted if the spacing between grooves remains between ¼ inch and 1 inch. The Engineer may require removal and replacement of deck surfaces that are not grooved as required. If the Engineer determines that grooves are too shallow but allow decks to remain in place, regroove after the concrete attains the required minimum 28-day flexural or compressive strength. Use a machine built specifically for grooving pavements, with blades 0.095 inch ±0.003 inch wide, spaced randomly from ¾ inch to 1¼ inches on centers . Orient grooves along the initial grooving at right angles to the centerline of the pavement or skewed no greater than the maximum skew of the bridge. Cut grooves uniformly ⅛ inch deep. Control and minimize dust from grooving operations . Remove and dispose of residue from the grooving operations to prevent debris from entering drainage systems.
4.Surface Tolerances. As soon as practical, check surface tolerances . If surfaces do not meet the specified tolerances, grind with a carborundum brick or other Department -approved methods . If grinding to obtain evenness results in an elevation below the limits shown on the plans, the Engineer will direct the Contractor to take corrective action at no additional cost to the Department . Position bridge seats within ⅛ inch of elevations shown on the plans . Finish bridge seats under bearings or masonry plates to an unevenness of no greater than 1⁄16 inch. MDOT Standard Specifications for Construction Section 706
7-52 Cast the tops of concrete subfootings within ½ inch of the elevations
shown on the plans and footings, wingwalls, parapets, slope walls, headers, and other surfaces within ¼ inch of the elevations shown on the plans. For final deck surfaces, cast decks to within a tolerance of ⅛ inch over 10 feet. Before acceptance, the Engineer will check the deck with a 10 foot stra ightedge and mark defective areas . Remove or reduce high spots , ridges, and other defects greater than ⅛ inch by rubbing with a carborundum brick and water or grinding and re-grooving.
N.Curing . Protect steel reinforcement from curing compound overspray . For air temperatures below 40°F, cure concrete in accordance with subsection 706.03.J . For air temperatures of 40°F and above, cure concrete in accordance with this section. Prepare and test work progress specimens, as necessary, in accordance with section 10 02.
1.Top Surfaces Exposed in the Completed Structure
a.Other than Bridge Decks. Immediately upon completion of concrete finishing operations, spray curing compound uniformly on the concrete surface. Use transparent or white curing compound. Apply white curing compound at a rate of at least 1 gallon of compound per 150 square feet . Apply transparent curing compound in two coats at a rate of at least 1 gallon of compound per 300 square feet for each coat . Apply the second coat when the first coat dries suf ficiently to avoid runoff but no more than 2 hours after applying the first coat . Do not dilute the curing compound.
b.Bridge Decks. Use a two-phase continuous 7-day wet -cure procedure. Before beginning concr ete placement operations, demonstrate to the Engineer that curing materials and equipment are on-site and that equipment is in operating condition. Immediately after the bleed water sheen leaves the textured concrete surface, begin the first phase of the c uring procedure by spraying a single coat of curing compound over the surface . Apply the curing compound at a rate of at least 1 gallon per 150 square feet of surface. Do not leave more than 10 feet of textured concrete surface exposed without curing compound. Prepare clean, contaminant -free burlap by soaking it in clean water for at least 12 hours before beginning concrete placement . Immediately before use, drape or suspend the burlap sheeting vertically to remove excess water that may dilute or damage plastic concrete . Cover concrete surfaces with wet burlap when the curing compound has dried sufficiently to prevent adhesion, MDOT Standard Specifications for Construction Section 706
7-53 and the concrete surface can support it without deformation, but
no more than 4 hours after the concrete placement . Do not allow the burlap to dry once it is in place. Do not use b urlap-polyethylene (Burlene) or other products with impervious surfaces. Install a network of soaker hoses over the wet burlap when the concrete surface can support it without deformation. Use soaker hoses perforated throughout their lengths within the limits of curing . Use soaker hoses of lengths and capacities capable of applying cure water uniformly and continuously over the entire bridge deck surface without the need to move the hoses periodically . Prevent excessive localized water discharge that may damage concrete surfaces . Use non- perforated hose outside the limits of curing . Demonstrate to the Engineer that soaker hose systems provide uniform and thorough coverage of the deck surface. Place a layer of transparent or white polyethylene film at least 4 mils thick over the deck surface and the soaker hose system . Overlap seams in the polyethylene at least 10 inches . Activate the wet cure system and maintain it to ensure uninterrupted wet curing of the deck surface. Control the water runoff to prevent soil erosion or hazards to traffic . Do not allow curing water runoff to discharge directly into surface waters. Maintain the wet cure until the concrete attains the required minimum 7 -day flexural or compressive strength and for at least 7 days following concrete placement . Do not remove the wet cure system based on 7-day compressive strengths attained in less than 7 days . Do not form or cast succeeding portions onto the bridge deck prior to completion of the 7-day two-phase continuous wet cure. Ensure that excess or ponding cure water is removed prior to casting of succeeding structure portions.
2.Top Surfaces to Whic h Succeeding Portions of the Structure Will Be Bonded . Maintain top surfaces on which succeeding portions of the structure will be placed including, but not limited to, medians, shoulders, sidewalks, barriers, parapets, membrane waterproofing, tops of backwalls, tops of diaphragms, and latex overlays, free of curing compound. Begin wet curing when the concrete hardens sufficiently to prevent marring or water damage. Cure these surfaces by keeping them continuously wet until the co ncrete attains the required minimum 7-day flexural or compressive strength and for at least 7 days following concrete placement . Do not form or cast succeeding portions MDOT Standard Specifications for Construction Section 706
7-54 onto the bridge deck prior to completion of the 7-day , two-phase
continuous wet cure. Forming of barriers and other appurtenances on raised sidewalks and brush blocks is permitted provided the wet cure is maintained.
3.All Surfaces Other than Top Surfaces. Cure surfaces, other than top surfaces, by keeping continuously wet until the concrete attains at least 70 % of its required minimum 28-day flexural or compressive strength and for at least 5 days following concrete placement . Alternat ively, cure concrete by leaving forms or other waterproof devices in place during the curing period or by applying transparent membrane curing compound for structures. Do not use membrane curing compound on surfaces requiring water curing and bonding of additional concrete or surfaces requiring application of joint waterproofing or protective coatings or penetrat ing sealers . Clean surfaces of steel dowels, anchors, waterstops, exposed reinforcing steel, and similar devices of curing compound before encasement. For structures, apply transparent membrane curing compound in two coats, each with at least 1 gallon of compound per 300 square feet of surface . Apply the first coat immediately after removing forms . Apply the second coat from 30 minutes to 2 hours after applying the first coat. Apply curing compound using a brush, roller, or spray equipment capable of producing a uniform film without causing the compound to run or sag. Obtain the Engineer ’s approval for spray equipment before use. If the method of applying the compound does not produce a uniform film, stop using the curing compound and keep the concrete surf ace wet for the required curing period.
O.Removing Falsework and Temporary Supports . Leave falsework and temporary supports for concrete structures other than railings in place until the concrete attains at leas t 70% of its required minimum 28-day flexural or compressive strength and for at least 5 days following concrete placement . Falsework for railings may be removed after 15 hours. Remove materials used to construct falsework outside low -water limits to at least 6 inches below the finished ground surface. Remove falsework material inside low -water limits to the stream bed. MDOT Standard Specifications for Construction Section 706
7-55 P. Removing Forms . Do not remove vertical forms, including bulkheads at
construction joints, until at least 15 hours after completion of the pour . Remove forms under slab spans, beams, girders, and brackets in accordance with subsection 706.03.O . If forms are braced against finished work portions subject to movement due to temperature changes, remove restraining falsework or adjust to prevent damage to the new work.
Q.Placing Beams on Substructure Units. Do not place beams until substructure concrete attains at least 70% of the required minimum 28-day flexural or compressive strength.
R.Finishing Hardened Concrete
1.General . Remove concrete fins and irregular projections from surfaces, except those that will not be exposed or those not requiring waterproofing. Clean honeycomb areas, broken corners or edges, cavities produced by form ties, other defects, and holes greater than ¾ inch in diameter and ⅜ inch deep. Keep surfaces saturated with water until pointed and trued with mortar . Mix the mortar using cement and fine aggregate of the proportions used in the concrete grade finished. Use a cement mixture composed of two-thirds of the brand used in t he concrete and one-third white cement . Use fine aggregate from the same source as used in the concrete. Use workable mortar that has attained initial set . Restore consistency by reworking but not retempering. Cure mortar patches in accordance with subsect ion 706.03.N.
2.Rubbed Surface Finish . If the contract requires a rubbed surface finish, start rubbing as soon as possible after removing forms and completing pointing and truing required in accordance with subsection 706.03.R.1. Immediately before beginning rubbing work, keep the concrete saturated with water for at least 1 hour. Allow time before wetting concrete to allow mortar in pointing of holes and defects to set . Do not damage mortar used in pointing of holes and defects . Rub the surfaces with a medium-coarse carborundum brick. Do not paint or plaster surfaces with neat cement or mortar . Continue rubbing to obtain a uniform surface, including the removal of form marks, projections, and irregularities, and filling of voids . Leave paste in place produced by this rubbing. After casting all concrete above the treated surface, obtain the final finish by rubbing with a fine carborundum brick and water . Continue rubbing to produce a smooth surface, uniform in color. After completion of final r ubbing and after the surface dries, rub with burlap to remove loose powder . Leave rubbed surfaces free of MDOT Standard Specifications for Construction Section 706
7-56 unsound patches, paste, powder, and marks that the Engineer
determines objectionable.
S.Penetrating Water -Repellent Treatment . Before applying the material, provide the Engineer with the product data sheets showing the manufacturer ’s recommended surface preparation, application procedure, and temperature range. Unless adjacent steel surfaces require coating after concrete cleaning, protect them to prevent damage. If damage occurs, repair it according to the contract at no additional cost to the Department.
1.Application . Apply penetrating water repellent material in accordance with the manufacturer ’s recommendations and at the application rate specified in the Qualified Products List . Do not dilute or alter penetrating water repellent material.
2.Limitations . Cure concrete at least 28 days before treating. Allow concrete to air dry during the final 48 hours o f the curing period. Apply penetrating water repellent material to surface dry concrete. Apply penetrating water repellent material when the concrete and the air temperature are within the range recommended by the manufacturer but no colder than 40°F . Do not spray the water repellent material if wind, rain, or other conditions are present that would adversely affect the application.
T.Electrical Grounding System . Use electricians licensed in the State of Michigan and experienced in grounding system installation to perform grounding work . Install a ground at each side of the bridge, at opposite ends. Weld bonding jumpers across the steel structure at the expansion joints and across the steel fence posts at expansion joints . Size bonding jumpers, as approved by the Engineer, to allow for the movement of the expansion joints . Install grounding cables down the piers or abutments from the bonding jumpers, fence posts, or steel fence to the grounding rod. Make connections wi th exothermic welds . Use the required mold and associated equipment for each connection. Install bonding jumpers and grounding cables to allow for at least 2 inches of expansion between connections. Measure ground resistance using the fall -of-potential method and do not exceed 25 ohms . If a single 8-foot grounding rod does not attain 25 ohms, drive additional 8-foot grounding rods, added to the top of the first rod or driven as a second ground, and connect to the first ground. MDOT Standard Specifications for Construction Section 706
7-57 Place grounding cables and tops of grounding rods at least 12 inches
below finished ground.
U.Name Plates. Furnish and install name plates as shown on the plans . Before installation, submit name plates with the required data imprinted legibly in the surface to the Engineer for approval.
V.Wall Drain. Attach wall drain strips as recommended by the manufacturer . Peel geotextile layers from the core at the lower edge and wrap around the foundation underdrain. Provide additional geotextile sections to completely encapsulate the pipe -strip junct ion. Shingle lap geotextile to preclude entrance of backfill material. Hold the top composite strip snug against the wall using mechanical means or a heavy bead of caulk, as approved by the Engineer, until the backfill is place d. Repair damage to composite strips or replace the strip. Deliver and store composite strips in ultraviolet -resistant wrapping. Protect composite strips from prolonged exposure to sunlight in accordance with the manufacturer ’s instructions. 706.04. Measurement and Payment Pay Item Pay Unit False Decking ................................................................................ Square Foot Reinforcement, Steel .............................................................................. Pound Reinforcement, Steel, Epoxy Coated ...................................................... Pound Reinforcement, Stainless Steel ............................................................... Pound Reinforcement, Steel, Culv and Headwall .............................................. Pound Conc, Grade __ ............................................................................... Cubic Yard Conc, Grade 3500, Subfooting ........................................................ Cubic Yard Substructure Conc ........................................................................... Cubic Yard Substructure Conc, High Performance ............................................ Cubic Yard Superstructure Conc ........................................................................ Cubic Yard Superstructure Conc, High Per formance ......................................... Cubic Yard Superstructure Conc, Night Casting ................................................ Cubic Yard Superstructure Conc, Night Casting, High Performance .................. Cubic Yard Water Repel lent Treatment, Penetrating ........................................ Square Yard Expansion Joint Device ............................................................................. Foot Expansion Joint Device, Cover Plate ......................................................... Foot Pipe Sleeve, __ inch ................................................................................. Each Pipe Sleeve, __ inch, Placed .................................................................... Each Conduit, __ inch ......................................................................................... Foot Conduit, __ inch, Placed ............................................................................ Foot MDOT Standard Specifications for Construction Section 706
7-58 Superstructure Conc, Form, Finish, and Cure
(Structure Identification) ................................................................ Lump Sum Superstructure Conc, Form, Finish, and Cure, Night Casting (Structure Identification) ................................................................ Lump Sum Bridge Ltg, Furn and Rem (Structure Identification) ......................... Lump Sum Bridge Ltg, Oper and Maintain ......................................................... Cubic Yard Conc, Low Temperature Protection .................................................. Cubic Yard Elec Grounding System ............................................................................ Each Wall Drain ...................................................................................... Square Foot Aesthetic Texturing ........................................................................ Square Yard
A.General . Unless otherwise specified, the Engineer will calculate pay quanti ties for pay items listed in this subsection based on the lines and dimensions shown on the plans . The Engineer will calculate concrete volumes without subtracting the volume of steel reinforcement or steel H-piling .
B.False Decking . The Engineer will measur e False Decking for the total area protected, including beam widths . The unit price for False Decking includes the cost of providing, installing, maintaining, moving, and removing false decking material or barges.
C.Steel Reinforcement . The Engineer will cal culate the weight of bars or bar mats, plain or coated, from the theoretical bar weights in accordance with Table 706- 2, based on the total calculated weight for the bar sizes and lengths, mesh, or bar mats . The Engineer will not make allowance for the wei ght of coating. Table 706- 2: Weights for Reinforcing Bars Bar Size Designation Weight (lb/ft) Diameter, Round Sections (inch) No. 3 0.376 0.375 No. 4 0.668 0.500 No. 5 1.043 0.625 No. 6 1.502 0.750 No. 7 2.044 0.875 No. 8 2.670 1.000 No. 9 3.400 1.128 No. 10 4.303 1.270 No. 11 5.313 1.410 No. 14 7.65 1.693 No. 18 13.60 2.257 MDOT Standard Specifications for Construction Section 706
7-59 The unit prices for Reinforcement, Steel ; Reinforcement, Steel, Epoxy
Coated ; Reinforcement, Stainless Steel ; and Reinforcement, Steel, Culv and Headwall include the cost of furnishing and installing the reinforcement .
D.Structure Concrete. Conduct concrete quality control as specified in section 1002 and the contract . The Engineer will conduct quality assurance as specified in section 1003 and the contract . The Department will pay for concrete required for this work based on the quality assurance results. Provide substructure concrete and superstructure concrete for bridge structures. Provide concrete of the grade require d for box and slab culverts, headwalls, parapets, wingwalls, retaining walls, tremie seals, and other structures. The Engineer will measure superstructure concrete for decks based on batch plant tickets with deductions made for material wasted or rejected. The unit prices for Substructure Conc ; Substructure Conc, High Performance; Conc, Grade __; and Conc, Grade 3500, Subfooting include the cost of forming, finishing, and curing. If the contract requires casting concrete against steel sheet piling, the Engineer will calculate the concrete volume based on an outline to the midpoint of the corrugations in the sheet piling section. The Engineer will not make deductions in concrete volumes for piles embedded 12 inches or less . If casting concrete footings on or against excavated rock, the Engineer will make an allowance in concrete volume for rock overbreak within 6 inches outside and 6 inches below the neat outline of the footing. The Engineer will measure, and the Department will pay for , concret e placed by pumping as concrete placed by other methods . The Department will not adjust the unit price of concrete as a result of adjustments in aggregate proportions, an increase in cement to facilitate the use of pumping equipment, or for the water -cemen t slurry pumped through the discharge pipe at the beginning of a pour.
E.Water Repellent Treatment, Penetrating . The unit price for Water Repellent Treatment, Penetrating includes the cost of preparing concrete surfaces and providing and placing water -repell ent material.
F.Expansion Joint Device. The Engineer will determine Expansion Joint Device quantities by the joint device length placed within the limits in the contract or authorized by the Engineer, including allowance for vertical heights and the terminal assemblies at the curbs, sidewalks , or barriers . MDOT Standard Specifications for Construction Section 706
7-60 The unit price for Expansion Joint Device includes the cost of providing
and placing attaching hardware for the device and all materials and labor required for proper installation of the expansion joint , end plates, and terminal assemblies at the curbs, sidewalks , or barriers .
G.Expansion Joint Device, Cover Plate. The unit price for Expansion Joint Device, Cover Plate includes providing the cover plate and associated hardware for proper installation of the cover plate. The Engineer will determine Expansion Joint Device, Cover Plate quantities by measuring the length of cover plate place d within the limits shown on the plans in the contract or authorized by the Engineer.
H.Conduit and Pipe Sleeve. The unit prices for Conduit, __ inch and Pipe Sleeve __ inch include the cost of providing and installing conduit or pipe sleeve. The unit prices for Conduit, __ inch, Placed and Pipe Sleeve, __ inch , Placed include the cost of installing conduit or pipe s leeve provided by others. The Department will not make additional payments to the Contractor for additional work of forming for conduit or ducts.
I.Superstructure Concrete, Form, Finish, and Cure . The Engineer will measure Superstructure Conc, Form, Finish, and Cure as a unit for each structure. The unit prices for Form, Finish, and Cure pay items include the cost of finishing and curing concrete, designing, fabricating, providing, and erecting forms or permanent metal deck forms and providing and installing polystyrene.
J.Bridge Lighting
1.Furnishing and Removing . The Engineer will measure Bridge Ltg, Furn and Rem as a unit for each structure. The unit price for Bridge Ltg, Furn and Rem includes the cost of furnishing, placing, and removing the lighting system for nighttime lighting.
2.Operating and Maintaining . The Engineer will measure Bridge Ltg, Oper and Maintain based on cubic yards of superstructure concrete cast at night . The unit price for Bridge Ltg, Oper and Maintain includes the cost of operating and maintaining the lighting system.
K.Low Temperature Protection . If the contract does not include a separate item for Conc, Low Temperature Protection and the Department orders low-temperature protection work due to Department -caused delays, or the Department orders an expedited progress schedule, the Department and MDOT Standard Specifications for Construction Section 706
7-61 the Contractor will agree on a unit price for Conc , Low Temperature
Protection before beginning protection work. The Department will pay for Conc, Low Temperature Protection based on the concrete quantity actually protected if the quantity did not increase due to the Contractor ’s failure to perform the work as shown on the progress schedule or due to the Contractor ’s perform ance of more work than shown on the progress schedule.
L.Wall Drain. The unit price for Wall Drain includes the cost of providing and attaching geocomposite and a dditional geotextile to wrap the foundation underdrain. The Engineer will measure, and the Department will pay for , foundation underdrain in accordance with subsection 404.04.
M.Electrical Grounding System . The unit price for Elec Grounding System includes t he cost of providing and installing the complete system to ground the bridge on two sides.
N.Aesthetic Texturing . The Engineer will measure Aesthetic Texturing by the square yard of the area textured without allowance for the shape and depth of the texturing. The unit price for Aesthetic Texturing includes:
1.Providing form liners;
2.Replac ing damaged form liners;
3.Install ing form liners;
4.Initial test sections;
5.Subsequent test sections, if any;
6.Repairing c oncrete surfaces that do not meet the quality and finish of the test section;
7.Shop drawings; and
8.Release agents.
O.Providing and Placing Interim Curing Material . The unit prices for the relevant structural concrete pay items include the cost of providing and placing interim curing material on bridge deck top surfaces exposed in the completed structure.
P.Name Plates. The cost of providing, fabricating, imprinting, and installing name plates on structures is included in the unit prices for other items of work.
Q.Unstable Foundations . The Department will pay for special treatment for unstable foundations at the unit price or authorized unit price for the item of work.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 393–425 of 1,146.