CONCRETE STRUCTURES SECTION 610 229 SECTION 610 — CONCRETE STRUCTURES
610.1Description.
This work consists of providing, placing, finishing, and curing concrete bridges, culverts, and miscellaneous structures.
610.2Materials.
610.3Construction.
610.3.1 Submittals.
workmanship meet the contract requirements. Provide detailed personnel, equipment, methods, and procedures to ensure the specified quality of all appl icable materials and related production and field operations. Follow the submittal procedures outlined in Section 105.4. Upon receipt of approved quality control plans, the contractor may begin work. At a minimum, provide the following information in the p lan:
placing, protecting, curing, temperature monitoring, and consolidating the concrete mix in approved forms to make a dense homogeneous concrete, in accordance wi th the requirements of Section 610.3.4.
placement in the plan and mix design. Submit a placement plan for placing concrete by pump. At a minimum, include pump location, vertical and horizontal work r each, pump capability, placement sequence, delivery configuration, and contingency for equipment malfunction.
Provide proof of the flatwork certification to the engineer before concrete placement.
CONCRETE STRUCTURES SECTION 610 230 a. Provide a hot or dry weather placement and curing plan when placing concrete in hot or dry weather. Include detailed procedures for reducing the hazards of an increased rate of cement hydration, flash set, loss of water due to evaporation, high concrete ingredient temperatures, and the increased difficulty of concrete placement and finishing, in accordance with the requi rements of Section 610.3.5.A.
occurred within 7 calendar days of anticipated concrete placement. Include detailed procedures for production, transporting, placing, protecting, curing, and temperatu re monitoring of concrete during cold weather, in accordance with the requirements of Section 610.3.5.C.
accordance with Section 105.4.
and temperature control of concrete in mass elements. Include a resume for the specialty engineer, detailing relevant experience on at least 5 thermal control proje cts. Ensure that the specialty engineer follows the procedure outlined in Section 207 of the ACI Manual of Concrete Practice to formulate, implement, administer, and monitor a temperature control plan, making adjustments as necessary to ensure compliance w ith Sections 610.3.4.D.3 and 610.3.6.B. ii. Provide an analysis of the anticipated thermal developments in the mass concrete elements for all expected project temperature ranges using the selected mix design, casting procedures, and materials. Submit a copy of any software models used for the pr ediction of peak temperatures with the site and element specific data to the engineer for approval with the analysis, including electronic files in the software used. Describe the measures and procedures intended to maintain, monitor, and control the tempe rature differential between the interior and exterior of the mass concrete elements, and the maximum temperature. iii. Describe methods for preventing thermal shock. iv. Include a minimum of 1 level of redundancy for all equipment and materials to maintain a continuous pour as part of the contractor's proposal.
placements to the engineer. Designate an employee, approved by the specialty engineer, as qualified to inspect monitoring device installation and record temperatur e readings.
texture, true to the required grade and cross -section, in accordance with the requirements of Sections 610.3.4.D.4 and 610.3.6.A. Include detailed procedures for production, transporting, placing, protecting, curing, and temperature monitoring, consolidating the concrete mix in approved forms to make a dense homogeneous concrete, and contingency for equipment malfunction.
provisions and details for emergency construction joints including shear keys, bonding agents, joint sealants, waterstops, and additional reinforcement, in accordanc e with the requirements of Section 610.3.3. CONCRETE STRUCTURES SECTION 610 231 4. Use permanent steel bridge deck forms for concrete deck slabs of bridges, when shown in the contract.
steel, the physical and section properties for all permanent steel bridge deck form sheets, and a clear indication of locations of form support by steel beam flanges subject to tensile stresses. Have an engineer registered in the State of Delaware sign and seal these drawings and calculations.
welds meet the AASHTO/AWS D1.5 Bridge Welding Code.
projected plan area of the metal forms. If the weight calculated exceeds the weight allowance for SIP metal forms and the concrete required to fill the forms shown in the contract, submit a method to modify the supporting components to support the excess weight.
50 pounds per square foot for construction loads. Use a unit working stress in the steel sheet of not more than 0.725 of the specified minimum yield strength of the material provided, but not to exceed 36,000 -PSI.
exceed 1/180 of the form span or 1/2 -inch, whichever is less, for form spans of 10 -feet or less, or 1/240 of the form span or 3/4 -inch, whichever is less, for form spans greater than 10 -feet. In all cases, do not use a total loading of pounds per square foot that is less than 20 plus the product of the deck thickness measured in inches multiplied by 12.5.
span parallel to the form flutes.
of Cold Formed Steel Structural Members, latest published edition.
supporting structural members. 610.3.2 Formwork.
temporary protective shield in accordance with Section 604.
sheets directly on the top of steel beam flanges. Fasten sheets securely to form supports and maintain a minimum bearing length of 1 -inch at each end for metal forms. Place form supports in direct contact with the flange of the steel beam. Make all attachments for coated metal forms using bolts, clips, screws, or other approved means. Secure forms to flanges in tension or to structural steel bridge elements fabr icated from non -weldable grades of steel by means other than welding directly to the member. CONCRETE STRUCTURES SECTION 610 232 2. For any permanent exposed steel with damaged galvanized coating, thoroughly clean, wire brush, and paint with 2 coats of galvanizing compound to the satisfaction of the engineer. Do not touch up minor heat discoloration in areas of welds.
steel bridge deck forms such that they are mortar tight. Ensure that slurry does not leak through the forms during the deck pour. Responsibility for any damage to persons or property due to leaking through the forms is in accordance with Section 10 7.10. Additional shielding may be placed beneath the forms to catch leakage during the deck pour if desired. 610.3.3 Joints.
construction joint plan.
otherwise in the contract. Leave the joint with a scored finish in accordance with Section 610.3.4.C. Bevel the forms for keys so that removal will not dama ge the concrete. Clean construction joints of surface laitance, curing compound, and other materials before placing fresh concrete against the surface of the joint. Use an abrasive blast or other approved methods to clean horizontal construction joints to expose clean aggregate. Flush construction joints with water and allow to dry to a saturated surface dry condition immediately before placing concrete.
no less than 3 -inches from the face of the concrete. Extend the water -stop into each section of the concrete a distance of at least 2 -inches or as specified in the contract.
locations identified in the construction joint plan. Apply epoxy bonding compound in accordance with manufacturer's recommendations.
finish true to line and elevation. All exposed construction joint edges shall have a 3/4 -inch v - notch. Construct all construction joints so that feather edging does not occur.
joints sealed with sealants or water -stops, and joints with combinations of these features.
Remove mortar and other debris from open joints.
polystyrene board. Use a single piece of joint filler for each joint. Anchor joint filler material to 1 side of the joint with a waterproof adhesive.
damage to the joint material. Splice, weld, or solder joints to be continuous and watertight. Prevent contamination of water -stop surfaces while embedding the water - stop in concrete. Ensure that all portions of the water -stop designed for embedment remain tightly enclosed by concrete. CONCRETE STRUCTURES SECTION 610 233 610.3.4 Placing Concrete.
threaded projection above the nut to between 3/16 -inch and 1 -inch.
lighting system before starting the concrete operations.
from tools, screeds, and conveying equipment. Clean and clear all surfaces that come in contact with concrete. Moisten the forms with water before placing concrete .
concrete placement plan. Place concrete continuously to prevent unplanned cold joints or damage to newly set concrete. Regulate concrete placement so that the pressures caused by the wet concrete do not exceed those used in the design of the forms. Place concrete into forms using a method that does not segregate the mix from a homogenous consistency. Deposit concrete mix as near as possible to final position. Discharge concrete within 5 -feet of final placement point. Limit lift thickness to 2 -feet. Do not exceed the capacity of the vibrators to consolidate and merge the concrete with the previous lift.
placed through any conveyance. Equip chutes on steep slopes with baffles or reverses. Do not place concrete with chute arrangements longer than 25 -feet.
diameter pipe. Prime pump with a cementitious grout material. Discharge priming grout into an approved collection area until fresh undiluted concrete discharges from the pump line. Operate the pump to produce a continuous stream of co ncrete without air pockets or segregation. Upon pumping completion, eject any concrete remaining in the pipeline planned to use in the work in such a manner that no contamination or separation of the concrete ingredients occurs. Provide samples of concrete for test purposes taken from the discharge end of the conduit system as close as possible to the final position of the concrete.
the surface coating of the reinforcement steel. Protect protruding steel for subsequent pours. Clean any protruding steel upon completion of the pour before subsequent pours.
vibration. Use internal vibration except for thin sections using forms designed for external vibration. Provide adequately sized vibrators to accomplish the work, wi th 1 or more spare vibrators in case of breakdown. Use immersion -type vibrators featuring heads covered with rubber or other resilient non -metallic material to consolidate concrete reinforced with epoxy - coated reinforcement. Vibrate at the point of deposit . Insert vibrators vertically and withdraw slowly to avoid segregation or grout pockets. Vibrate in a uniform pattern spaced less than 1.5 times the radius of visible effectiveness. Do not move the concrete laterally with vibrators. CONCRETE STRUCTURES SECTION 610 234 C. Finishing Plastic Concrete
finish the surface with a wooden float. Tool construction and expansion joints with an edger. Leave joint filler exposed.
float. Broom the surface lightly in a transverse direction. Use an edging tool on edges and expansion joints. Lay out surfaces in blocks with an approved grooving tool. Correct deviations of more than 1/8 -inch when checked with a 5 -foot straightedge.
inch depth without dislodging the coarse aggregate or exposing the reinforcing steel.
masonry plate contact area to provide full and even bearing.
with a steel trowel. Provide a finished surface that varies by no more than 1/16 -inch. Grind surfaces that fail to conform to the required flatness.
elastomeric bearings, provide a float finish.
are free of mud and silt.
discharge, long enough to reach the bottom of the placement and marked in 1 -foot increments. ii. Attach tremie tube to a funnel or hopper with a capacity of at least 1/2 cubic yard. iii. Provide a valve at the lower end of the discharge tube that closes tightly while charging the tremie and lowering it into position. The valve must be able to be fully open in the lowered position. Alternately, provide a foam rubber plug in the hopper that moves through the tremie tube when pushed by the concrete, forcing water or slurry from the tremie tube. iv. Provide at least 2 tremie tubes to ensure continuous concrete placement.
discharge end of the tube. Do not move the tremie laterally during concrete placement. Keep the discharge end of the tremie tube fully submerged in the freshly deposited concrete to prevent water infiltration. CONCRETE STRUCTURES SECTION 610 235 e. Place tremie concrete in 1 continuous operation. Place concrete at a rate that prevents aggregate segregation, allows flow over the entire placement area, and keeps the concrete level in the tremie tube stable. Keep the top surface of concrete as level as possible. Maintain balance d hydrostatic pressures to prevent form failure and movement of water through the plastic concrete. Do not place tremie concrete by pumping directly to the bottom of placement. Place tremie concrete only in the presence of the engineer.
unsatisfactory material from the concrete surface by means that do not damage the concrete surface. Chip off high spots on the concrete surface that would prevent placement of steel reinforcing bars.
interior and the exterior of the element at points approved by the engineer. Monitor a minimum of 2 independent sets of interior and exterior points for each element to provide redundancy in case of a device failure. Locate the monitoring points at the geometric center of the element for the interior point, and 2 inches from the surface along the shortest line from the geometric center to the nearest surface of the eleme nt for the exterior point.
information at a maximum interval of 15 -minutes. Provide devices that operate for a maximum range of 0 to 200 degrees with an accuracy of +/- 2 degrees F.
approve the installation of monitoring devices.
and the contractor. Review the approved bridge deck placement plan and procedures for deck construction.
easy to control, of sufficient weight to strike off the surface at the specified grade, and provides a uniform treatment over the deck surface. Unless a longitu dinal construction joint has received approval under the construction joint plan, use transverse screeds that extend the full width of the deck between curbs or parapets.
support lines. If the skew angle changes at supports, adjust the angle of the screed accordingly as the finishing machine progresses across the deck slab. If a l ongitudinal construction joint is approved, place the portion on either side of the joint and finish separately.
the main structural members, or on form supports. Ensure that the rails are rigid enough to permit the screed to finish the surface of the deck within the requirements of this section. CONCRETE STRUCTURES SECTION 610 236 (3) When placing the rails within the roadway area, elevate the rails above the deck to allow simultaneous finishing by hand of any portion not finished by the screed. Fabricate and install rail supports extending above the roadway surface in such a manner as to allow removal to at least 2 -inches below the top surface of the deck slab. Place a fusion bonded epoxy coating or other approved corrosion resistant material on all portions of the rail support to remain in the deck concrete. When placing rail suppo rts in that portion of the deck, under the curbs, or parapets, place the supports at least 2 -inches from the face of the curb, parapet walls, or outside edge of the slab.
necessary to obtain a bridge deck true to the required grade and cross -section, with allowances made for anticipated settlement. Provide supports that will ensure no springing or deflection occurs under the weight of the finishing equipment, and located so that finishing equipment may operate without interruption over the entire bridge deck. ii. Do not use vibrating screeds or longitudinal type screeds unless specifically approved by the engineer.
fog sprays and curing compounds, and for inspection. Support the work bridge or platform outside the limits of the concrete placement.
up maintains clear cover of reinforcement, accounts for roadway grades and cross -slopes, and incorporates deflection from the wet deck concrete to produce the fina l deck elevations given in the contract. Before placing bridge deck concrete, check all falsework and make all necessary adjustments.
ii. personnel and equipment, as identified in the approved bridge deck placement plan, will deliver, place, spread, finish, and cure a minimum of 20 cubic yards of concrete per hour; iii. all finishing tools and equipment are in satisfactory condition for use; and iv. weather protective equipment is provided.
at the pre -pour meeting. Place particular emphasis on proper concrete vibration to avoid tears, aggregate silhouettes, honeycombs, and voids, especially at constru ction joints, expansion joints, valleys, and ends of form sheets.
On simple spans, and for all sections between construction joints for continuous spans, place the concrete by beginning at the end and working along the roadway. After the initial placement in any 1 section of a continuous span, do not make any placement until the cylinder strength of all previously placed concrete in the deck of that group reaches at least 0.5f ‘c. ii. During the screeding operation, keep an adequate supply of concrete ahead of the screed and maintain a slight excess immediately in front of the screed. CONCRETE STRUCTURES SECTION 610 237 g. Finish bridge decks and approach slabs to a smooth surface using approved power - driven finishing machines. Use hand finish methods for irregular areas when approved.
dragging fabric over the final screeded concrete. ii. To remove local irregularities, finish the surface with a float or other approved device and to leave sufficient mortar at the surface of the concrete for subsequent texturing. Finish the surface without adding water.
of at least 14 -days after placing concrete. Begin curing by fog spraying during the placing and finishing operations. Apply fogging continuously, rather than intermittently, after the finishing operation until wet covering material has been placed over the concrete surface. Augment with ha nd-held fogging equipment as needed. ii. Keep the surface continuously wet for the entire curing period by covering with two layers of wet burlap or one layer of wet burlap plus a polyethylene sheet or a polyethylene coated burlap blanket. iii. Apply curing protection within 15 -minutes after depositing the concrete and before the surface of the concrete has lost its surface wetness or sheen appearance. Submerge the burlap in water for at least 8 -hours before the scheduled start of the concrete placement. Drain the burlap of excess water prior to the application. Provide burlap that is free from cuts, tears, uneven weaving, and contaminants. Place the burlap such that the edges are lapped a minimum of 6-inches . Commence continuous burlap wetting 10 -minutes after its placement and keep continuously wet and protected from displacement for the entire curing period. iv. Keep bridge decks covered and continuously wet for the entire curing period by the use of soaker hoses. Provide a system of soaker hoses that circulate water continuously and that are located to ensure a completely wet surface for the entire curing period.
Test finished surfaces of concrete in accordance with the contract using an inertial profiler or 10 -foot straight edge. The maximum allowable longitudinal and transverse deviation is 1/4-inch in 10 -feet. Provide a 10 -foot straight edge for testing smoothness. ii. Surface Corrections. Use diamond grinding to remove deviations exceeding 1/4 -inch in 10 -feet. Submit information on similar types of work performed with the proposed grinding equipment, including references if requested by the en gineer.
longitudinal grooves parallel to the centerlines. Complete a longitudinal grooving operation that results in a uniformly grooved deck surface. Saw grooves 1/8 to 3/16 -inch wide; 3/16 to 1/4-inch deep; and on 3/4 -inch centers. Terminate grooves 18 -inches, plus or minus 1 -inch, from the face of the parapet or curb line. If metal drainage inlets extend more than 18 - CONCRETE STRUCTURES SECTION 610 238 inches from the parapet or curb line, end all grooves on the bridge deck surface within 6 - inches of the drainage inlet perimeter. At expansion joints, end all grooves within 6 -inches of the joint. Produce grooves that are continuous across joints less than 1/2 -inch wide. ii. Perform continuous removal of waste materials, including slurry, resulting from the grooving operations in accordance with Sections 106.8 and 104.12.
sub-foundation concrete.
provisions included in the contract. 610.3.5 Weather and Environmental Conditions.
increased rate of cement hydration, flash set, loss of water due to evaporation, high concrete ingredient temperatures, and the increased difficulty of concrete placement and finishing. Ensure the temperature of the concrete at the point of discharge does not exceed 90 degrees F. Ensure the temperature of the concrete for bridge decks at the point of discharge does not exceed 85 degrees F.
aggregates by fogging or other means that will not result in a high variation of moisture content within the stockpile. Use chipped or crushed ice in the mix as a portion of the mixing water on a pound for pound basis, provideds uch measure is determined at the time of placement in the mix. If using ice, melt before discharging the batch from the mixing unit. Cool water by refrigeration or other means that will pr ovide a uniform mixing water temperature.
contact with the concrete by water spray or other approved methods when the ambient temperature rises above 90 degrees F. Ensure there is no standing water in the concrete forms as a result of the spraying procedures. Provide personnel and equipment in accordance with the approved placement and curing plan to place the concrete without delays that may cause excessive slump loss and evaporation due to over -mixing or exposure before placement.
may begin as soon as possible. Keep new concrete shaded from the sun, shielded from the wind, and wet with water, or protected by other methods to retain t he moisture throughout the curing period. Use windscreens of sufficient dimensions, water fogging, or other approved means of supplying moisture to prevent shrinkage cracking due to moisture loss.
high temperatures by using the methods outlined below. Limit the evaporation rate of the exposed concrete surface to less than 0.15 pounds per square foot per h our as calculated by ACI 305 Hot Weather Concreting Figure 2.1.5. DelDOT Materials & Research Section will provide copies of the chart upon request. To maintain the deck surface evaporation rate below 0.15 pounds per square foot per hour, take 1 or more of the following actions:
application of the curing cover. Produce a fine fog mist with the nozzle to maintain a sheen of CONCRETE STRUCTURES SECTION 610 239 moisture on the concrete surface without ponding. Do not work any applied moisture back into the surface.
placement.
weather, cover new concrete to prevent damage. Provide sufficient material for covering at the site of the work for immediate use.
falling below 40 degrees F or the ambient temperature at the site falling below 50 degrees F, for a period of 12 -hours or more.
in the shade, away from artificial heat, is above 35 degrees F. Maintain the concrete mixture at a temperature of 55 degrees F or above by heating aggregate, water, or both. Limit aggregate and water temperature to a maximum of 150 degrees F. Do not heat aggregate by direct gas or oil flame or on sheet metal over fire.
available at the project site before placing concrete. Remove snow, ice, and frost from the surfaces, including reinforcement and subgrade against concrete placem ent. Place concrete only when the temperatures of all surfaces that will come into contact with the concrete are at least 35 degrees F and maintained at a temperature of 35 degrees F or above during placement.
indicated in Table 610.3 -1 for the curing period defined in Section 610.3.6. Monitor maximum and minimum surface temperature with a measuring device that is acc urate to within 2 degrees
area in an accessible location. Table 610.3 -1. Surface Temperature Requirements During Curing Minimum Section Size Dimension Maximum Temperature of Concrete During Curing Period Maximum Allowable Temperature Drop in Any 24 -Hour Period During Curing Under 1 ft 57°F 50°F 1-3 ft 57°F 40°F Over 3ft up to 6 ft 50°F 29°F Over 6 ft 50°F 29°F
for curing. Heat the structure uniformly. Reduce heat gradually in the enclosure so that the temperature will not drop more than 20 degrees F in 8 -hours. CONCRETE STRUCTURES SECTION 610 240 6. Place insulation on the concrete as soon as initial set will permit. Provide insulating blankets faced or covered, top and bottom, with polyethylene or similar waterproofing material. Ensure that sufficient thickness of blankets will maintain the concrete surface temperature at or above the required temperatures indicated in Table 610.3 -1, for the curing period defined in Section
610.3.6Secure blankets around the perimeter of the work to minimize infiltration of ambient
air and loss of heat during the protection period. Should the temperature of the work fall below the required temperatures indicated in Table 610.3 -1 during the protection period, take immediate corrective actions. 610.3.6 Curing Concrete.
Keep the surface of the concrete moist by a water fog spray applied without damaging the surface. Commence curing operations immediately after the free water leaves the surface and completing finishing operations. C ure concrete in accordance with the requirements of Table 610.3 -1.
covering with materials kept continuously and thoroughly wet. Use multiple layers of burlap, or other approved materials that do not discolor or otherwise damage the concrete.
surfaces not exposed to view in the completed work, or on surfaces where approval is granted by the engineer. Apply the curing solution uniformly at the manufacturer's specified application rate. Do not use liquid membrane curing compounds on surfaces wit h a required rubbed finish, or on surfaces of construction joints unless the membrane is removed by sandblasting before placing new concrete against the joint. Apply curing compound immediately after form removal and the concrete is finished. Apply the solution by power operated atomizing spray equipment in 1 or 2 separate applications. Apply the second coating within 30 minutes of the first. Use hand operated sprayers for coating sma ll areas if needed. Thoroughly mix membrane solutions containing pigments. Agitate the mixture during application. Reapply the solution, at the specified rate, to membrane film damaged during the curing period by weather or construction activities .
concrete. Install the cover when the concrete is wet. Use sheets of the widest practical width. Overlap sheets a minimum of 6 -inches and seal with pressure sensitive tape, mastic, glue, or other approved methods to form a waterproof cover over the entire concrete surface. Secure the waterproof sheet material to prevent displacement by wind. Immediately repair sheets torn or damaged during the curing period.
with Section 610.3.6.B.1.b when forms are removed before 7 uninterrupted calendar days. Allow to cure for at least 7 uninterrupted calendar days after placing concrete.