420Concrete Substructures

2.1 Concrete. Provide concrete in accordance with Item 421, “Hydraulic Cement Concrete.” Provide the class of

concrete for each type of structure or unit as shown on the plans or in conformance with pertinent governing specifications.

2.2 Grout or Mortar . Provide grout for dowelling anchors or precast connections in accordance with DMS -4675 ,

“Cementitious Grouts and Mortars for Miscellaneous Applications.”

2.3 Latex Curing Materials. Provide an acrylic -polymer latex admixture (acrylic resin emulsion in accordance

with DMS -4640 , “Chemical Admixtures for Concrete”) suitable for producing polymer -modified concrete or mortar. Do not allow latex to freeze.

2.4 Reinforcing Steel . Provide reinforcing steel in accordance with Item 440, “Reinforcement for Concrete.”

2.5 Expansion Joint Material . Provide materials in accordance w ith DMS -6310 , “Joint Sealants and Fillers.”

 Provide preformed fiber expansion joint material that conforms to the dimensions shown on the plans .  Provide preformed bituminous fiber material unless otherwise specified.  Provide asphalt board that conforms to dimensions shown on the plans .  Provide re- bonded neoprene filler that conforms to the dimensions shown on the plans.

2.6 Water stop. Provide rubber or polyvinyl chloride (PVC) waterstops in accordance with DMS -6160 , “Water

Stops, Nylon- Reinforced Neoprene Sheet, and Elastomeric Pads,” unless otherwise shown on the plans.

2.7 Curing Materials . Provide membrane curing compounds in accordance with DMS -4650 , “Hydraulic Cement

Concrete Curing Materials and Evaporation Retardants.” Provide cotton mats that consist of a filling material of cotton “bat” or “bats” (at least 12 oz. per square yard) completely covered with unsized cloth (at least 6 oz. per square yard) stitched longitudinally with continuous parallel rows of stitching spaced at less than 4 in., or tuft both longitudinally and transversely at intervals less than 3 in. Provide cotton mats that are free of tears and in good general condition. Provide a flap at least 6 in. wide consisting of two thicknesses of the covering and extending along one side of the mat. Provide polyethylene sheeting that is at least 4 mils thick and free of visible defects. Provide only clear or opaque white sheeting when the ambient temperature during curing exceeds 90°F or when applicable to control temperature during mass pours. Provide burlap- polyethylene mats made of burlap impregnated on one side with a film of opaque white pigmented polyethylene, free of visible d efects. Provide laminated mats that have at least one layer of an impervious material such as polyethylene, vinyl plastic, or other acceptable material (either as a solid sheet or impregnated into another fabric) and are free of visible defects. 511 Provide burlap material that complies with AASHTO M 182, Class 3 (10 oz. per square yard) with the following additions .  Manila hemp may also be used to make burlap.  Do not use burlap fabricated from bags .  Do not use burlap containing any water -soluble ingredient tha t will retard the setting time of concrete. Provide used burlap that compl ies with the requirements stated above and that has only been used previously for curing concrete. “ Like new ” cleanliness is not expected, but contamination with any substance foreign to the concrete curing process, such as grease or oil, will be cause for rejection.

2.8 Epoxy . Provide epoxy materials in accordance with DMS -6100 , “Epoxies and Adhesives,” unless otherwise

specified.

3.1 Transporting and Placing Equipment . Use appropriate transporting and placing equipment such as

buckets, chutes, buggies, belt conveyors, pumps, or other equipment as necessary. Ensure concrete is not transported or conveyed by equipment made of aluminum. Use tremies to control the fall of concrete or for underwater placement. Use tremies that are watertight and of large enough diameter to allow the placement of the concrete but less than 14 in. in diameter. Construct the tremie so the bottom can be sealed and opened once the tremie has been fully charged with concrete for underwater placements. Use pumps with lines at least 5 in. inside diameter (ID) where Grade 2 or smaller coarse aggregate is used, and at least 8 in. ID for Grade 1 coarse aggregate.

3.2 Vibra tors. Use immersion -type vibrators for consolidation of concrete. Provide at least one standby vibrator

for emergency use. Furnish vibrator head covered by a rubberized or elastomeric cover when used near epoxy coated reinforcing steel.

3.3 Temperature Recordi ng Equipment . Use strip chart temperature- recording devices, recording maturity

meters in accordance with Tex -426-A , or other approved devices that are accurate to within ±2°F within the range of 32– 212°F for mass concrete operations, for cold weather placements, and as otherwise specified.

3.4 Artificial Heating Equipment . Use artificial heating equipment as necessary for maintaining the concrete

temperatures in accordance with Section 420.4.7.11., “Placing Concrete in Cold Weather.”

3.5 Spraying Equipment . Use mechanically powered pressure sprayers, either air or airless, with appropriate

atomizing nozzles for the application of membrane curing. Use hand- pressurized spray equipment with two or three fan -spray nozzles if approved. Ensure the spray from each nozzle overlaps the spray from adjacent nozzles by approximately 50%.

3.6 Concrete Testing Equipment . Provide testing equipment for use by the Engineer in accordance with

Section 421.3.3., “Testing Equipment.”

4.1 Schedule Restrictions. Construct and open completed structures to traffic with the following limitations

unless otherwise shown on the plans .

4.1.1 Setting Forms . Attain at least 2,500 psi compressive strength before erecting forms on concrete footings

supported by piling or drilled shafts, or on individual drilled shafts. Erect forms on spread footings and culvert footings after the footing concrete has aged at least 2 curing days in accordance with Section 420.4.10., “Curing Concrete.” Place concrete only after the forms and reinforcing steel have been inspected by the Engineer. Support tie beam or cap forms by falsework on previously placed tie beams only if the tie beam concrete has attained a compressive strength of 2,500 psi and the member is properly supported to eliminate stresses not provided for in the design. Maintain curing as required until completion of the curing period. Place superstructure forms or falsework on the substructure only if the substructure concrete has attained a compressive strength of 3,000 psi.

4.1.2 Removal of Forms and Falsework. Keep in place weight -supporting forms and falsework for bridge

components and culvert slabs until the concrete has attained a compressive strength of 2,500 psi in accordance with Section 420.4.11., “Removal of Forms and Falsework.” Keep all forms for mass placements in place for 4 days following concrete placement unless otherwise approved based on the outcome of the heat control plan in accordance with Section 420.4.7.14., “Mass Placements.”

4.1.3 Placement of Superstructure Members. Erect or place superstructure members or precast substructur e

members only after the substructure concrete has attained a compressive strength of 3,000 psi.

4.1.4 Opening to Traffic . Direct traffic culverts may be opened to construction traffic when the design strength

specified in Section 421.4.1., “Classification of Concrete Mix Designs,” has been attained if curing is maintained. Obtain approval before opening direct traffic culverts to the traveling public. Open other noncritical structural and nonstructural concrete for service upon the completion of curing unless ot herwise specified or directed.

4.1.5 Post -Tensioned Construction. Ensure strength requirements shown on the plans for structural elements

designed to be post -tensioned are met for stressing and staged loading of structural elements.

4.1.6 Backfilling . Backfill in acco rdance with Section 400.3.3., “Backfill.”

4.2 Plans for Falsework and Forms . Submit plans for falsework and forms for the following items: vertical

forms for piers and single column bents; load supporting forms for caps and tie- beams; form attachments for bridges to be widened; and other items as indicated or directed. Provide design calculations when requested. Show all essential details of proposed forms, falsework, and bracing. Have a licensed professional engineer design, seal, and sign these plans. Department approval is not required, except as shown in Table 1 of 513 Item 5, “Control of the Work,” when forms or falsework are located such that public safety can be affected, but the Department reserves the right to request modifications to the plans. The Contrac tor is responsible for the adequacy of these plans. Design job- fabricated formwork assuming a weight of 150 pcf for concrete, and include a live- load allowance of 50 psf of horizontal surface of the form. Do not exceed 125% of the allowable stresses used b y the Department for the design of structures .

4.3 Falsework. Design and construct falsework to safely carry the maximum anticipated loads, including wind

loads, and to provide the necessary rigidity. Consult AASHTO’s Guide Design Specifications for Bridge Temporary Works and Construction Handbook for Bridge Temporary Works for falsework and shoring information not indicated below. Submit details in accordance with Section 420.4.2., “Plans for Falsework and Forms.” Design job- fabricated falsework assuming a wei ght of 150 pcf for concrete, and include a minimum live- load allowance of 50 psf of horizontal surface of the form. Do not exceed 125% of the allowable stresses used by the Department for the design of structures. Do not exceed the manufacturer’s maximum allowable working loads for moment and shear or end reaction for commercially produced structural units used in falsework. Include a minimum live- load allowance of 35 psf of horizontal form surface in determining the maximum allowable working load for commercially produced structural units. Provide timber that is sound, in good condition, and free of defects that would impair its strength. Provide timber that meets or exceeds the species, size, and grade requirements shown on the submitted falsework plans. Provide wedges made of hardwood or metal in pairs to adjust falsework to desired elevations to ensure even bearing. Do not use wedges to compensate for incorrectly cut bearing surfaces. Use sills or grillages large enough to support the superimposed load without settlement. Take precautions to prevent settling of the supporting material unless the sills or grillages are founded on solid rock, shale, or other hard materials. Place falsework that cannot be founded on a satisfactory spread f ooting on piling or drilled shafts with enough bearing capacity to support the superimposed load without settlement. Drive falsework piling to the required resistance determined by the applicable formula in Item 404, “Driving Piling.” Design drilled shafts for falsework to carry the superimposed load using both skin friction and point bearing. Weld in accordance with Item 448, “Structural Field Welding.” Securely brace each falsework bent to provide the stiffness required, and securely fasten the bracing to each pile or column it crosses. Remove falsework when it is no longer required or as shown on the submitted falsework plan. Pull or cut off foundations for falsework at least 2 ft. below finished ground level. Completely remove falsework, piling, or drilled shafts in a stream, lake, or bay to the approved limits to prevent obstruction to the waterway.

4.4 Forms . Submit formwork plans in accordance with Section 420.4.2., “Plans for Falsework and Forms.”

4.4.1 General . Provide forms of either timber or metal except where otherwise specified or permitted.

Design forms for the pressure exerted by a liquid weighing 150 pcf. Take the rate of concrete placement into consideration in determining the depth of the equivalent liquid. Include a minimum live- load allowance of 50 psf of horizontal surface for job- fabricated forms. Do not exceed 125% of the Department’s allowable stresses for the design of structures . Do not exceed the manufacturer’s maximum allowable working loads for moment and shear or end reaction for commercially produced structural units used for forms. Include a minimum live- load allowance of 35 psf of 514 horizontal form surface in determining the maximum allowable working load for commercially produced structural units. Provide steel forms for round columns unless otherwise approved. Refer to Item 427, “Surface Finishes for Concrete,” for additional requirements for off- the-form finishes . Provide commercial form liners for imprinting a pattern or texture on the concrete surface as shown on the plans and in accordance with Section 427.4.3.5., “Form Liner Finish.” Provide forming systems that are practically mortar -tight, rigidly braced, and strong enough to prevent bulging between supports, and maintain them to the proper line and grade during concrete placement. Maintain forms in a manner that prevents warping and shrinkage. Do not allow offsets at form joints to exceed 1/16 in. Use only material that is inert, non- biodegradable, and nonabsorptive for forms to be left in place. Construct all forms to permit their removal without marring or damaging the concrete. Clean all forms and footing areas of any extraneous matt er before placing concrete. Provide openings in forms if needed for the removal of laitance or foreign matter. Treat the facing of all forms with bond- breaking coating of composition that will not discolor or injuriously affect the concrete surface. Take c are to prevent coating of the reinforcing steel. Complete all preparatory work before requesting permission to place concrete. Cease placement if the forms show signs of bulging or sagging at any stage of the placement, and remove the portion of the concrete causing this condition immediately as directed. Reset the forms and securely brace them against further movement before continuing the placement .

4.4.2 Timber Forms . Provide properly seasoned, good- quality lumber that is free of imperfections that would

affec t its strength or impair the finished surface of the concrete. Provide timber or lumber that meets or exceeds the requirements for species and grade shown on the submitted formwork plans. Maintain forms or form lumber that will be reused so it stays clean and in good condition. Do not use any lumber that is split, warped, bulged, or marred, or that has defects in any way that will produce inferior work. Promptly remove such lumber from the work. Provide form lining for all formed surfaces except:  the inside of culvert barrels, inlets, manholes, and box girders;  surfaces that are subsequently covered by backfill material or are completely enclosed; and  any surface formed by a single finished board or by plywood. Provide form lining of an approved type such as masonite or plywood. Do not provide thin membrane sheeting such as polyethylene sheets for form lining. Use plywood at least 3/4 in. thick. Place the grain of the face plies on plywood forms parallel to the span between the supporting studs or joists unless otherwise shown on the submitted form drawings. Use plywood for forming surfaces that remain exposed that meets the requirements for B -B Plyform Class I or Class II Exterior of the U.S. Department of Commerce Voluntary Product Standard PS 1. Space studs and joists so the facing form material remains in true alignment under the imposed loads . Space wales closely enough to hold forms securely to the designated lines, scabbed at least 4 ft. on each side of joints to provide continuity. Place a row of wales near the bottom of each placement. 515 Place facing material with parallel and square joints, securely fas tened to supporting studs . Place forms with the form panels symmetrical (long dimensions set in the same direction) for surfaces exposed to view and receiving only an ordinary surface finish in accordance with Section 420.4.13., “Ordinary Surface Finish. ” Make horizontal joints continuous. Make molding for chamfer strips or other uses of materials of a grade that will not split when nailed and can be maintained to a true line without warping. Dress wood molding on all faces. Fill forms at all sharp corners and edges with triangular chamfer strips measuring 3/4 in. on the sides unless otherwise shown on the plans . Use metal form ties of an approved type or a satisfactory substitute of a type that permits ease of removal of the metal to hold forms in place. Cut back wire ties at least 1/2 in. from the face of the concrete. Use devices to hold metal ties in place that can develop the strength of the tie and adjust to allow for proper alignment . Entirely remove metal and wooden spreaders that separate the forms as the concrete is being placed. Provide adequate cleanout openings for narrow walls and other locations where access to the bottom of the forms is not readily attainable.

4.4.3 Metal Forms. Requirements for timber forms regarding design, mortar tightness, filleted corners, beveled

projections, bracing, alignment, removal, reuse, and wetting also apply to metal forms , except metal forms do not require lining unless as specifically shown on the plans. Use form metal thick enough to maintain the true shape without warping or bulging. Countersink all bolt and rivet heads on the facing sides. Design clamps, pins, or other connecting devices to hold the forms rigidly together and to allow removal without damage to the concrete. Use metal forms that pres ent a smooth surface and line up properly. Keep metal free of rust, grease, and other foreign materials.

4.5 Drains . Install and construct weep holes and roadway drains as shown on the plans.

4.6 Placing Reinforcement and Post -Tensioning. Place reinforcement in ac cordance with Item 440. Do not

weld reinforcing steel supports to other reinforcing steel except where shown on the plans. Place post -tensioning ducts, anchorages, and other hardware in conformance with the approved prestressing details and in accordance w ith Item 426, “Post -Tensioning.” Keep ducts free of obstructions until all post - tensioning operations are complete.

4.7 Placing Concrete. Give the Engineer sufficient advance notice before placing concrete in any unit of the

structure to permit the inspection of forms, reinforcing steel placement, and other preparations. Do not place concrete when impending weather conditions would impair the quality of the finished work. Place concrete in early morning or at night or adjust the placement schedule for more favorable weather when conditions of wind, humidity, and temperature are such that concrete cannot be placed without the potential for weather -related distress. Adequately illuminate the entire placement site as approved when mixing, placing, and finishing con crete in non-daylight hours. Furnish adequate shelter to protect the concrete against damage from rainfall or freezing temperatures in accordance with this Item if changes in weather conditions require protective measures after work starts. Continue operat ions during rainfall only if approved. Use protective coverings for the material stockpiles. Cover aggregate stockpiles only to the extent necessary to control the moisture conditions in the aggregates. 516 Allow at least 1 curing day after the concrete has achieved initial set before placing strain on projecting reinforcement to prevent damage to the concrete.

4.7.1 Placing Temperature. Place concrete in accord ance with the following temperature limits for the classes of

concrete defined in Section 421.4.1., “Classification of Concrete Mix Designs.”  Place Class C, F, H, K, or SS concrete only when its temperature at time of placement is between 50°F and 95°F. Increase the minimum placement temperature to 60°F if slag cement is used in the concrete.  Place Class S conc rete, used in this Item only as indicated for culvert top slabs, only when its temperature is between 50°F and 85°F. Increase the minimum placement temperature to 60°F if slag cement is used in the concrete.  Place Class A, B, and D concrete only when its temperature at the time of placement is greater than 50°F .  Place mass concrete in accordance with Section 420.4.7.14., “Mass Placements,” only when its temperature at the time of placement is between 50°F and 75°F.

4.7.2 Transporting Time . Begin the discharge of concrete delivered in truck mixers within the times shown in

Table 14 of Item 421.

4.7.3 Workability of Concrete . Place concrete with a slump as specified in Section 421.4.2.5., “Slump.” Water

may be added to the concrete before discharging any concrete from the truck to adjust for low slump, provided that the maximum mix design water -cement ratio is not exceeded. Mix concrete in accordance with Section 421.4.6., “Mixing and Delivering Concrete,” after introduction of any additional water or chemical admixtures. Do not add water or chemical admixtures after any concrete has been discharged.

4.7.4 Transporting Concrete . Transport concrete by buckets, chutes, buggies, belt conveyors, pumps, or other

methods . Protect concrete transported by conveyors from sun and wind to prevent loss of slump and workability. S hade or wrap with wet burlap pipes through which concrete is pumped as necessary to prevent loss of slump and workability . Arrange and use chutes, troughs, conveyors, or pipes so the concrete ingredients will not be separated. T erminate such equipment in vertical downspouts when necessary to prevent segregation. Extend open troughs and chutes, if necessary, down inside the forms or through holes left in the forms . Keep all transporting equipment clean and free of har dened concrete coatings. Discharge water used for cleaning clear of the concrete.

4.7.5 P reparation of Surfaces. Thoroughly wet all forms and hardened concrete on which concrete is to be

placed before placing concrete on them. Remove any remaining puddles of excess water before placing concrete. Provide surfaces that are in a moist, saturated surface-dry (SSD) condition when concrete is placed on them . Ensure the subgrade or foundation is moist before placing concrete on grade. Lightly sprinkle the subgrade i f dry.

4.7.6 E xpansion Joints . Construct joints and devices to provide for expansion and contraction as shown on the

plans . Use light wire or nails to anchor any preformed fiber joint material to the concrete on one side of the joint . Ensure finished joints conf orm to the plans with the concrete sections completely separated by the specified opening or joint material . 517 Remove all concrete within the joint opening soon after form removal and again where necessary after surface finishing to ensure full effectiveness of the joint .

4.7.7 C onstruction Joints . A construction joint is the joint formed by placing plastic concrete in direct contact with

concrete that has attained its initial set. Monolithic placement means the manner and sequence of concrete placing do not create a construction joint . Make construction joints of the type and at the locations shown on the plans. Additional joints in other m embers are not permitted without approval. Place authorized additional joints using details equivalent to those shown on the plans for joints in similar locations . Make construction joints square and normal to the forms unless otherwise required. Use bulkheads in the forms for all vertical joints . Thoroughly roughen the top surface of a concrete placement terminating at a horizontal construction joint as soon as practical after initial set is attained. Thoroughly clean the hardened concrete surface of all loose material, laitance, dirt, and foreign matter, and s aturate it with water. Remove all free water and moisten the surface before concrete or bonding grout is placed against it. Ensure the surface of the existing concrete is in an SSD condition just before placing subsequent concrete. Wet the existing concrete by ponding water on the surface for 24 hr. before placing subsequent concrete. Use high- pressure water blasting if ponding is not possible to achieve SSD conditions 15–30 min. before placing the concrete. An SSD condition is achieved when the surface remains damp when exposed to sunlight for 15 min. Draw forms tight against the existing concrete to avoid mortar loss and offsets at joints . Bonding agents are not required unless indicated otherwise. Coat the joint surface with bonding mortar, grout, epoxy, or other material if a bonding agent is required as shown on the plans. Provide Type V epoxy in accordance with DMS -6100 for bonding fresh concrete to hardened concrete. Place the bonding epoxy on a clean, dry surface, and place the fresh concrete while the epoxy is still tacky. Place bonding mortar or grout on a surface that is SSD and place the concrete before the bonding mortar or grout dries. Place other bonding agents in conformance with the manufacturer’s recommendations .

4.7.8 H andling and Placing. Minimize segregation of the concrete and displacement of the reinforcement when

handling and placing concrete. Produce a uniform, dense compact mass . Ensure concrete free f alls no more than 5 ft. except in the case of drilled shafts, thin walls such as in culverts, or as allowed in conformance with other Items. Remove any hardened concrete splatter ahead of the plastic concrete. Fill each part of the forms by depositing concrete as near to i ts final position as possible. Do not deposit large quantities of concrete at one point and run or move the concrete along to fill the forms . Deposit concrete in the forms in layers of suitable depth but no more than 36 in . deep unless ot herwise permitted. Avoid cold joints in a monolithic placement. Sequence successive layers or adjacent portions of concrete so t hey can be vibrated into a homogeneous mass with the previously placed concrete before it sets. Allow no more than 1 hr. to elapse between adjacent or successive placements of concrete when re- vibration of the concrete is shown on the plans , except as otherwise allowed by an approved placing procedure. This time limit may be extended by 1/2 hr. if the concrete contains at least the minimum recommended dosage of a Type B or Type D admixture. 518 4.7.9. Consolidation. Carefully consolidate concrete and flush mortar to the form surfaces using immersion -type vibrators. Do not use vibrators that operate by attachment to forms or reinforcement except where approved on steel forms . Vibrate the concrete immediately after deposit. Systematically space points of vibration to ensure complete c onsolidation and thorough working of the concrete around the reinforcement and embedded fixtures, and into the corners and angles of the forms. Insert the vibrators vertically where possible. Vibrate the entire depth of each lift, allowing the vibrator to penetrate several inches into the preceding lift. Do not use the vibrator to move the concrete to other locations in the forms. Do not drag the vibrator through the concrete. Thoroughly consolidate concrete along construction joints by operating the vibrator along and close to but not against the joint surface. Continue the vibration until the concrete surrounding reinforcements and fixtures is completely consolidated. Hand- spade or rod the concrete if necessary to ensure flushing of mortar to the surface of all forms .

4.7.10 Installation of Dowels and Anchor Bolts . When shown on the plans, provide an Adhesive Anchor Installer

certified by ACI. Install dowels and anchor bolts by casting them in place or by grouting with grout, epoxy, or epoxy mortar unless specified otherwise. Form or drill holes for grouting. Follow the manufacturer’s recommended installation procedures for pre -packaged grout or epoxy anchor systems. Test anchors if required on the plans or in conformance with other Items . Drill holes for anchor bolts to accommodate the bolt embedment required by t he plans. Make holes for dowels at least 12 in. deep unless otherwise shown on the plans. Make the hole diameter at least twice the dowel or bolt diameter, but not exceeding the dowel or bolt diameter plus 1- 1/2 in. when using cementitious grout or epoxy mortar. Make the hole diameter 1/16– 1/4 in. greater than the dowel or bolt diameter when using neat epoxy unless specified otherwise by the epoxy manufacturer . Thoroughly clean holes of all loose material, oil, grease, or other bond- br eaking substance, and blow them clean with filtered compressed air. Use a wire brush followed by oil -free compressed air to remove all loose material from the holes, repeating as necessary until no more material is removed. Ensure holes are in a surface- dry condition when epoxy -type materials are used and in a surface- moist condition when cementitious grout is used. Develop and demonstrate for approval a procedure for cleaning and preparing the holes for installation of the dowels and anchor bolts. Completely fill the void between the hole and dowel or bolt with grouting material. Follow exactly the requirements for cleaning in conformance with the product specifications for pre- packaged systems . Provide hydraulic cement grout for cast -in-place or grouted systems in accordance with DMS -4675 . Provide a Type III epoxy in accordance with DMS -6100 when neat epoxy is used for anchor bolts or dowels. Provide Type VIII epoxy in accordance with DMS -6100 when an epoxy grout is used. Provide grout, epoxy, or epoxy mortar as the binding agent unless otherwise shown on the plans . Provide other anchor systems as required on the plans .

4.7.11 P lacing Concrete in Cold Weather . Protect concrete placed under weather conditions where weather may

adversely affect results. Permission given by the Engineer for placing during cold weather does not relieve the Contractor of responsibility for producing concrete equal in quality to that placed under normal conditions. Remove and replace concrete as directed at the Contractor’s expense if it is determined unsatisfactory due to poor conditions . Do not place concrete in contact wi th any material coated with frost or with a temperature of 32°F or lower. Do not place concrete when the ambient temperature in the shade is below 40°F and falling unless approved. Place concrete when the ambient temperature in the shade is at least 35°F and rising or above 40°F . Provide and install recording thermometers, maturity meters, or other suitable temperature- measuring devices to verify all concrete is effectively protected as follows . 519  Maintain the temperature at all surfaces of concrete in bents, piers, culvert walls, retaining walls, parapets, wingwalls, top slabs of non- direct traffic culverts, and other similar formed concrete at or above 40°F for 72 hr. from the time of placement .  Maintain the temperature of all other concrete, including the bottom slabs (footings) of culverts, placed on or in the ground above 32°F for 72 hr. from the time of placement. Use additional covering, insulated forms, or other means and, if necessary, supplement the covering with artificial heating. Avoid applying heat directly to concrete surfaces. Cure in accordance with Section 420.4.10., “Curing Concrete,” during this period until all requirements for curing have been satisfied. Have all necessary heating and covering material ready for use before permission is granted to begin placement when impending weather conditions indicate the possible need for temperature protection.

4.7.12 Placing Concrete in Hot Weather . Keep the concrete at or below the maximum temperature at time of

placement in accordance with Section 420.4.7.1., “Placing Temperature.” Sprinkle and shade aggregate stockpiles or use ice, liquid nitrogen systems, or other approved methods as necessary to control the concrete temperature.

4.7.13 Placing Concrete in Water . Deposit concrete in water only when shown on the plans or with approval. Make

forms or cofferdams tight enough to prevent any water current passing through the space in which the concrete is being deposited. Do not pump water during the concrete placing or until the concrete has set for at least 36 hr. Place the concrete using a tremie or pump, or use another approved method, and do not allow it to fall freely through the water or disturb it after it is placed. Keep the concrete surface level during placement . Support the tremie or operate t he pump so it can be easily moved horizontally to cover all the work area and vertically to control the concrete flow. Keep the lower end of the tremie or pump hose submerged in the concrete. Use continuous placing operations until the work is complete. Design the concrete mix in accordance with Item 421 w ith a minimum cement content of 650 lb. per cubic yard for concrete to be placed under water. Include an anti -washout admixture in the mix design as necessary to produce a satisfactory finished product .

4.7.14 Mass Placements. Develop and obtain approval for a heat control plan for monolithic placements

designated on the plans as mass concrete to ensure the following during the heat dissipation period:  the temperature differential between the central core of the placement and the exposed concrete surface does not exceed 35°F and  the temperature at the central core of the placement does not exceed 160°F. Use the ConcreteWorks© software available from the Department, or another approved method in accordance with A CI 207, “Mass Concrete,” to develop the heat control plan. The Department will make available technical assistance on the use of ConcreteWorks©. Develop the heat control plan using historical temperature ranges for the anticipated time of the mass placemen t. Re -create the plan if the work schedule shifts by more than one month. The heat control plan may include a combination of the following elements:  selection of concrete ingredients including aggregates, gradation, and cement types, to minimize heat of hydration;  use of ice or other concrete cooling ingredients;  use of liquid nitrogen dosing systems;  controlling rate or time of concrete placement;  use of insulation or supplemental external heat to control heat loss;  use of supplementary cementing materials ; 520  use of a cooling system to control the core temperature; or  vary the duration for which formwork remains in place. Furnish and install two pairs of temperature- recording devices, maturity meters, or other approved equivalent devices. Install devices to measure the surface temperature no more than 3 in. from the surface. Install devices to measure the core temperature half the least dimension from the nearest surface near the point of maximum predicted heat. Use these devices to simultaneously measure the temperature of the concrete at the core and the surface. Maintain temperature control methods for 4 days unless otherwise approved in conformance with the submitted heat control plan. Do not use maturity meters to predict strength of mass concrete. Revise the heat control plan as necessary to maintain the temperature limitations shown above. If the core temperature exceeds 160°F, the mass concrete element will be subject to review and acceptance by the Engineer using forensic analyses to determine its potential reduction in service life or performance. Proceed with subsequent construction on the affected element only when notified regarding acceptance. Repair any resulting cracking if the temperature differential between the central core of the placement and the nearest concrete surface exceeds 35°F at no expense to the Department and revise the heat control plan as necessary to prevent further occurrences .

4.7.15 P lacing Concrete in Foundation and Substructure . Do not place concrete in footings until the depth and

character of the foundation have been inspected and permission has been given to proceed. Place concrete footings upon seal concrete after the cofferdams are free of w ater and the seal concrete is cleaned. Perform any necessary pumping or bailing during the concreting from a suitable sump located outside the forms . Construct or adjust all temporary wales or braces inside cofferdams as the work proceeds to prevent unauthorized construction joints . Omit forms when footings can be placed in a dry excavation without the use of cofferdams, if approved, and fill the entire excavation with concrete to the elevation of the top of footing. Place concrete in columns monolithically between construction joints unless otherwise directed. Columns and c aps or tie beams supported on them may be placed in the same operation or separately. Allow for settlement and shrinkage of the column concrete, if placed in the same operation, by placing it to the lower level of the cap or tie beam, and delay placement between 1 hr. and 2 hr. before proceeding with the cap or tie beam placement .

4.7.16 P lacing Concrete in Box Culverts. Allow between 1 hr. and 2 hr. to elapse where the top slab and walls are

placed monolithically in culverts more than 4 ft. in clear height before placing the top slab to allow for settlement and shrinkage in the wall concrete. Accurately finish the footing slab at the proper time to provide a smooth, uni form surface. Finish top slabs that carry direct traffic in accordance with Item 422, “Concrete Superstructures.” Give top slabs of fill -type culverts a float finish.

4.8 Extending Existing Substructures . Verify pertinent dimensions and elevations of the existing structure

before ordering any required materials.

4.8.1 Removal . Remove portions of the existing structure to the lines and dimensions shown on the plans or as

directed. Dispose of these materials as shown on the plans or as directed. Repair any portion of the remaining structure damaged by the construction. Do not use explosives to remove portions of the existing structure unless approved in writing. Do not use a demolition ball, other swinging weight, or impact equipment unless shown on the plans. Use pneumatic or hydraulic tools for final removal of concrete at the “break” line. Use removal equipment, as approved, that will not damage the remaining concrete. 521 4.8.2. Reuse of Removed Portions of Structure . Detach and remove all portions of the old structure that are to be incorporated into the extended structure to the lines and details as shown on the plans or as directed. Move the unit to be reused to the new location specified using approved methods. Place the reinforcement and extension concrete as shown on the plans.

4.8.3 Splicing Reinforcing Steel . Splice new reinforcing bars to exposed bars in the existing structure using lap

splices in accordance with Item 440, unless otherwise shown on the plans. The new reinforcing steel does not need to be tied to the existing steel where spacing or elevation does not match that of the existing steel , provided the lap length is attained. Weld in accordance with Item 448 when welded splices are permitted. Install any required dowels in accordance with Section 420.4.7.10., “Installation of Dowels and Anchor Bolts .”

4.8.4 Concrete Preparation . Roughen and clean concrete surfaces that are in contact with new construction

before placing forms. Prepare these construction joint surfaces in accordance with Section 420.4.7.7., “Construction Joints .”

4.9 Treatment and Finishing of Horizontal Surfaces . Strike off to grade and finish all unformed upper

surfaces. Do not use mortar topping for surfaces constructed under this Section. Float the surface with a suitable float after the concrete has been struck off. Slope the tops of caps and piers between bearing areas from the center slightly toward the edge, and slope the tops of abutment and transition bent caps from the backwall to the edge, as directed, so water drains from the surface. Give the concrete a smooth trowel finish. Construct bearing areas for steel units in accordance with Section 441. 3.11.6. , “Bearing and Anchorage Devices.” Give the bearing area under the expansion ends of concrete slabs and slab and girder spans a steel -trowel finish to the exact grades required. Give bearing areas under elastomeric bearing pads or nonreinforced bearing seat buildups a textured, wood float finish. Do not allow the bearing area to vary from a level plane more than 1/16 in. in all directions. Cast bearing seat buildups or pedestals for concrete units integrally with the cap or a construction joint. Provide a latex -based mortar, an epoxy mortar, or an approved proprietary bearing mortar for bearing seat buildups cast with a construction joint. Mix mortars in conformance with the manufacturer’s recommendations. Construct pedestals of Class C concrete, reinforced as shown on the plans or as indicated in Figure 1 and Figure 2. The Engineer of Record will design pedestals higher than 12 in. Figure 1 Section Through Bearing Seat Buildups Figure 2 Plan View of B earing Seat Buildups

4.10 Curing Concrete . Obtain approval of the proposed curing methods, equipment, and materials before placing

concrete. The Engineer may require the same curing methods for like portions of a single structure. Inadequate curing or facilities may delay all concrete placements on the project until remedial action is taken. A curing day is a calendar day when the temperature, taken in the shade away from artificial heat, is above 50°F for at least 19 hr. or, on colder days if the temperature of all surfaces of the concrete is maintained above 40°F, for the entire 24 hr. The required curing period begins when all concrete has attained its initial set unless specified otherwise. Tex -440-A m ay be used to determine when the concrete has attained its initial set. Cure all concrete for 4 c onsecutive days except as allowed for the curing options listed below. Use form or membrane curing for vertical surfaces unless otherwise approved. Use only water curing for horizontal surfaces of high- performance concrete (HPC ) or mass concrete. Use water or membrane curing for horizontal or unformed surfaces for all other concrete. Use one of the following curing options for vertical surfaces, unless specified otherwise.  Form cure for 48 hr. after placement .  Form cure for 12 hr. after placement followed by membrane curing .  For HPC, form cure for 48 hr. after placement followed by membrane curing.  For mass concrete, form cure in conformance with the heat control plan followed by membrane curing if forms are removed before 4 days. Apply membrane curing, if used, within 2 hr. of form removal. Use only water curing in accordance with this Section for the top surface of any concrete unit upon which concrete is to be placed and bonded at a later interval ( e.g., stub walls, caps with backwalls, and risers). Cure all other concrete in conformance with the pertinent Items. Use the following methods for curing concrete in accordance with this Item.

4.10.1 Form Curing. When forms are left in intimate contact with the concrete, other curing methods are not required except for exposed surfaces and for cold weather protection. Use another approved curing method if forms are removed before the 4- day required curing period.

523 4.10.2. Water Curing . Keep all exposed surfaces of the concrete wet continuously for the required curing time. Use water curing in accordance with concrete mixing water in Section 421.2. 5., “Water.” Do not use seawater or water that stains or leaves an unsightly residue. 4.10.2.1. Blankets. Keep the concrete continuously wet by maintaining wet cotton or burlap mats in direct contact with the concrete for the required curing time. Weight the mats adequately to provide continuous contact with all concrete. Cover surfaces that cannot be cured by direct contact with mats, forming an enclosure well anchored to the forms or ground so outside air cannot enter the enclosure. Provide sufficient moisture inside the enclosure to keep all surfaces of the concrete wet . 4.10.2.2. Water Spray. Overlap sprays or sprinklers to keep all unformed surfaces continuously wet . 4.10.2.3. Ponding. Cover the surfaces with at least 2 in. of clean granular material, always kept wet, or at least 1 in. of deep water. Use a dam to retain the water or saturated granular material.

4.10.3 Membrane Curing . Choose either Type 1- D or Type 2 membrane- curing compound unless otherwise shown

on the plans. Use the same type of curing compound on an individual member . Apply membrane curing just after free moisture has disappeared at a rate of approximately 180 sq . ft. per gallon. Do not spray curing compound on projecting reinforcing steel or concrete that will later form a construction joint. Do not apply membrane curing to dry surfaces. Dampen formed surfaces and surfaces that have been given a first rub, so they are moist at the time of application of the membrane. Leave the film unbroken for the minimum curing period specified when membrane is used for complete c uring. Correct damaged membrane immediately by reapplication of membrane. Polyethylene sheeting, burlap- polyethylene mats, or laminated mats in close contact with the concrete surfaces are equivalent to membrane curing.

4.11 Remov al of Forms and Falsework. Remove forms for vertical surfaces after the concrete has aged at least

12 hr. after initial set , provided the removal can be done without damage to the concrete, unless otherwise directed. Keep forms for mass placements in place for 4 days following concrete placement unless otherwise approved based on the outcome of the heat control plan in accordance with Section 420.4.7.14., “Mass Placements .” Leave in place weight -supporting forms and falsework spanning more than 1 ft. for al l bridge components and culvert slabs except as directed otherwise until the concrete has attained a compressive strength of 2,500 psi. Remove forms for other structural components as necessary. Remove inside forms (walls and top slabs) for box culverts and sewers after concrete has attained a compressive strength of 1,800 psi if an approved overhead support system is used to transfer the weight of the top slab to the walls of the box culvert or sewer before removal of the support provided by the forms. Forms or parts of forms may be removed only if constructed to permit removal without disturbing forms or falsework required to be left in place for a longer period on other portions of the structure. Remove all metal appliances used inside forms for alignment to a depth of at least 1/2 in. from the concrete surface. Make the appliances so metal may be removed without undue chipping or spalling of the concrete, and so it leaves a smooth opening in the concrete surface when removed. Do not burn off rods, bolts, or ties. Remove all forms and falsework unless otherwise directed.

4.12 Defective Work. Repair defective work as soon as possible. Remove and replace at the expense of the

Contractor any defect that cannot be repaired to the satisfaction of the Engineer. 524 4.13. Ordina ry Surface Finish . Apply an ordinary surface finish to all concrete surfaces. Provide surfaces with uniform appearance. Address defects and surface irregularities not consistent with the intent of the expected finish by the following:  Chip away all loose or broken material to sound concrete where porous, spalled, or honeycombed areas are visible after form removal .  Repair spalls in accordance with the Concrete Repair Manual available on the Department’s website .  Clean and fill holes or spalls caused by the removal of metal appliances used inside forms , with latex grout, cement grout, or epoxy grout as approved. Do not blend the patch with the surrounding concrete.  Remove all fins, rust staining, runs, drips, or mortar from surfaces that will be exposed. Smooth all form marks and chamfer edges by grinding or dry -rubbing.  Ensure all repairs are dense, well -bonded, and properly cured. Finish exposed large repairs to blend with the surrounding concrete where a higher class of finish is not specified. Apply an ordinary surface finish as the final finish to the following exposed surfaces unless specified otherwise:  inside and top of inlets ,  inside and top of manholes ,  inside of sewer appurtenances , and  inside of culvert barrels . Form marks and chamfer edges do not need to be smoothed for the inside of culvert barrels.

5.1 General . Concrete quantities will be based on the dimensions shown on the plans or those established in

writing by the Engineer. In determining quantities, no deductions will be made for chamfers less than 2 in. or for embedded portions of steel or prestressed concrete beams, piling, anchor bolts, reinforcing steel, drains, weep holes, junction boxes, electrical or telephone conduit, ducts and voids for prestressed tendons, or embedded portions of light fixtures. Variation in concrete headwall quantity incurred when an alternate bid for pipe is permitted will not be cause for payment adjustment. Quantities revised by a change in design, measured as specified, will be increased or decreased and included for payment.

5.2 Plans Quantity. Structure elements shown in Table 1 and measured by the cubic yard are plans quantity

measurement items. The quantity to be paid for plans quantity items is the quantity shown in the proposal , unless modified by Article 9.2., “Plans Quantity Measurement.” Additional measurements or calculations will be made if adjustments of quantities are required. No adjustment will be made for footings or other in- ground elements where the Contractor has been allowed to place concrete in an excavation without forms. 525 Table 1 Plans Quantity Payment (Cubic Yard Measurement Only) Culverts and culve rt wing walls Abutments Headwalls for pipe Footings Retaining walls Pile bent caps Inlets and manholes Post-tensioned elements Note —Other elements, including pier and bent concrete, may be paid for as “plans quantity” when shown on the plans.

5.3 Measured in Place. Items not paid for as “plans quantity” will be measured in place.