Section 569 — Concrete Overlays for Bridge Decks

Description

569.01This work consists of providing, placing, finishing, and curing concrete for bridge deck overlays.

Material

569.02Conform to the following Section and Subsections: Coarse aggregate for concrete 703.02 Concrete curing material and additives 711 Fine aggregate for concrete 703.01 Hydraulic cement 701.01 Pozzolans 701.03 Water for cementitious materials 725.01(a)

Construction Requirements

569.03Qualifications. Provide an on -site supervisor with experience placing concrete overlays on bridge decks. A t least 30 days before starting concrete overlay work, s ubmit a résumé for the on -site supervisor describing experience on at least two overlay projects with the specified overlay class within the past 3 years for approval. Include project names, locations, and contact information for project owners.

569.04Compositi on (Concrete Mix Design). Design and produce concrete overlay mixtures that conform to following:

(a)Table 569-1 for the class specified; and

(b)Section 4 of ACI 301, Specifications for Concrete Construction for determining required a verage compressive strength ( f'cr). Table 569-1

Composition of Concrete

Concrete

Overlay

Class Property Performance Characteristics

Total

Cementitious

Material

Content,

pounds per cubic yard(1) Maximum Water/

Cementitious

Material

Ratio(4) Slump, inches Air

Content,

percent Coarse

Aggregate

Size

Number

AASHTO

M 43(5) Maximum

Chloride

Permeability,

AASHTO

T 277, coulombs Average Bond

Strength at

14 Days, ASTM C1583 , pounds per square inch Minimum

Compressive

Strength,

AASHTO T 22 , pounds per square inch HPC(O)(2) 564 to 750 0.45 2 to 8 Table 552-1 7, 78, 8 1500 150 4500 LMC(3) 564 to 750 0.45 2 to 8 3.0 to 10.0 7, 78, 8 1500 150 4000

(1)The total cementitious material content includes portland cement and pozzolans added to the concrete mixture (such as ground granulated blast furnace slag, fly ash, and silica fume). Meet the requirements shown in Table 552 -2.

(2)Add 1.5 gallons per cubic yard of concrete of an approved Shrinkage Reducing Admixture (SRA) .

(3)Add 3. 5 gallons of latex emulsion admixture per 9 4 pounds of cement.

(4)Include the water contained in the aggregate above the amount of absorbed water in the calculation of the water -to-cementitious material ratio.

(5)Meet the processing requirements of AASHTO M 43, Table 1 – Standard Sizes of Processed Aggregate. Do not use gravel or alkali -silica reactive aggregates. Submit concrete overlay mix designs on Form FHWA 1608, 552 Structura l Concrete Mix Design Submittal . Verify the mix designs with trial mixes prepared according to Section 4 of ACI 301 from proposed sources or with previous concrete production data for the mixture submitted from proposed sources. Verify the performance char acteristics in Table 569-1. Submit written concrete mix designs for approval at least 36 days before production. Include the items listed in Subsections 552.03(a) (1) through (28) in each mix design submittal. Provide a new mix design for approval if a source of material changes or if the fine aggregate fineness modulus changes by more than 0.20.

569.05Strength -Maturity Relationship. If used, submi t strength -maturity relationships according to AASHTO T 325.

569.06Surface Preparation. Remove asphalt, asphalt membranes, and concrete overlays without damaging the concrete bridge deck. Micro mill according to Section 413 to remove existing overlays. Sound the bridge deck according to ASTM D4580 to identify unsound concrete in the deck. Do not perform surface preparation within 6 feet of a new overlay until 48 hours after its placement. Submit a repair plan for approva l that includes the following:

(a)Concrete repairs. Conform to Section 572.

(b)Surface profiling. Provide a minimum profile of ⅟ 16 inch and a maximum of ¼ inch on the substrate concrete to bond to the concrete. Use hydrodemolition according to Section 560 or a micro milling machine. After surface profiling approval and within 3 6 hours of expected overlay placement, shot blast and pressure wash the substrate concrete. Use a potable water source with a minimum water pressure of 4000 pounds per square inch. Remove concrete laitances, oils, fuels, and other foreign and loose material detrimental to achieving a sufficient bond. Cap ture debris from shotblasting and pressure washing, and properly dispose of it off site. Cover the prepared surface with polyethylene sheeting to prevent contamination.

(c)Saturation. Thoroughly water -soak the clean concrete surface for at least 2 4 hours before placing the overlay concrete. Do not use burlap. Remove puddles of standing water using a vacuum or other approved equipment. Do not use a blower or compressed air to remove water.

569.07Test Section. Prepare the substrate concrete surface using the same methods intended for the overlay placement. Construct a 9- by 9- foot test section on the substrate concrete at the same thickness as the overlay. Use the approved concrete mix design and the same methods of handling, placing, finishing, and curing intended for actual placement. Sample and test according to in Table 569-2 . Demonstrate the maturity meter operation. Use the strength -maturity relationship developed for the approved mix design to determine in- place compressive strength. Verify that the test section concrete has a similar time temperature relationship. Demonstrate methods for conforming to temperature requirements in Subs ection 569.11. Demonstrate methods for cleaning stains or efflorescence to provide uniform color on the concrete surface. Start production only after the test panel is approved.

569.08Mixing. Conform to Subsection 552.04 and the following:

(a)Class HPC(O). Provide ready- mixed concrete produced and delivered according to AASHTO M 157. (b) Class LMC. Provide volumetric proportioning and mixing equipment with an integral mobile unit with continuous mixing capability. Provide a mixer with the following:

(1)Capable of producing at least 6.0 cubic yards of concrete without recharging;

(2)Equipped with a cement metering device and recording meter accurate within a tolerance of minus 1 to plus 3 percent and with a device to record the cement quantity added to the mix; (3) Equipped with a latex tank with a standpipe marked in gallons and a latex metering device accurate within a tolerance of minus 1 to plus 2 percent;

(4)Equipped with a water flow control and flow indicator accurate within a tolerance of 2 percent in the range of expected use that is readily adjustable to provide for minor variations in aggregate moisture content;

(5)Equipped with controls to regulate the quantity of other components required to produce the specified mix; and

(6)Capable of discharging the mixture through a conventional chute directly in front of the finishing machine. Calibrate LMC equipment with material for the approved mix design within 6 months before the placement date. Keep the equipment maintained, calibrated, clean, and free of partially dried or hardened material. Protect latex emulsion from freezing and prolonged exposure to temperatures more than 85 °F. Store containers of latex admixture at the bridge site for no more than 10 days. Add reinforcing fibers to the concrete mixture according to the manufacturer’s recommendation s. Add fibers to the concrete mixture gradually to ensure the fibers are uniformly distributed throughout the concrete mixture.

569.09Delivery. Conform to Subs ection 552.05 , except do not use non- agitating equipment.

(a)Class HPC(O). If reinforcing fibers reduce workability, do not add additional water to the concrete mixture. Adjust workability using admixtures from the approved mix design. If the air content is low when the concrete arrives on site, add air -entraining agent and mix.

(b)Class LMC. Deliver concrete through the conventional chute of an integral mobile volumetric mixer directly in front of the finishing machine.

569.10Quality Control of Mix. Conform to Subs ection 552.06, except as modified in Table 569-2.

569.11Temperature and Weather Conditions. Before placement, maintain the temperature of the overlay concrete mixture between 45 and 80 ºF. Install maturity meter probes and monitor concrete temperatures according to AASHTO T 325. Monitor the temperature differential from the center of the concrete mass to the surface. Provide internal cooling, external heating, or insulation to ensure the temperature differential is no more than 3 5 °F during placing, curing, and immediately after curing ends. Using the strength- maturity relationship developed for the approved concrete mixture, determine in -place concrete compressive strength of the overlay. Measure concrete temperature and calculate in -place maturity.

(a)Cold weather. Conform to Subs ection 552.07(a) .

(b)Hot weather. Conform to Subs ection 552.07(b) .

(c)Evaporation. Conform to Subs ection 552.07(c) .

(d)Precipitation. Conform to Subs ection 552.07(d) .

569.12Handling and Placing Concrete. Conform to Subs ection 552.08 and the following:

(a)Placing meth ods.

(1)Class HPC(O). Do not broom mortar from the concrete from the front edge of the placement.

(2)Class LMC. Immediately ahead of placing overlay mixture, broom a thin coat of the concrete overlay mixture and scrub it into the surface as a grout- bond coat at the front edge of the placement. Work evenly over the surface in front of the front edge of the placement.

(b)Consolidation. Use a self -propelled finishing machine capable of forward and reverse movement under positive control. Ensure the length of the screed is sufficient to extend at least 6 inches beyond the edge of both ends of the section being placed. Provide a finishing machine capable of consolidating the concrete by vibration and of raising screeds to clear the concrete for traveling in reverse. Provide either a rotating roller -type or an oscillating screed -type finishing machine. Use rotating roller -type machines with one or more rollers, augers, and 1500 to 2500 vibrations per minute vibratory pans. Use oscillating screed -type machines with vibrators on the screeds whose frequency of vibration can be varied between 3000 and 15,000 vibrations per minute. Use metal screeds with a bottom face of at least 4 inches wide. Use hand -held vibrators at the concrete edges and adjacent to expansion joints. Remove and replace concrete represented by cylinders having a compressive strength less than 90 percent of the minimum 28 -day strength ( f' c).

569.13Construction Joints. Conform to Subs ection 552.09. In addition, form the vertical edge at construction joints by bulkhead or saw cut. Make construction joints straight and vertical.

569.14Expansion and Contraction Joints. Conform to Subs ection 552.10.

569.15Finishing Plastic Concrete. Conform to Subs ection 552.12. Use a self -propelled rotating cylinder machine, either single or double roller that is capable of forward or reverse movement under positive control. Equip the mach ine with an oscillating screed and other devices required to continuously spread, consolidate, and finish the plastic concrete. Ensure the screed extends the full width of the deck. Produce a longitudinal troweled finish along the gutter line for a 12 -inch width from the curb face. Proceed at a constant rate so final finishing is complete before a plastic film forms on the concrete surface. Install a construction dam or bulkhead in case of delays over an hour. During delays of 1 hour or less, protect the en d of the placement from drying with layers of wet burlap.

569.16Concrete Curing. Prevent plastic shrinkage cracking and crusting of the surface. Use the water method of curing according to Subs ection 552.13(b) . Use washed burl ap and apply soaker hoses or other approved methods to keep the coverings saturated at all times. Install maturity meter probes and monitor concrete temperatures according to AASHTO T 325. Maintain the concrete temperature of the outermost surfaces above 4 5 °F. Monitor the temperature differential from the center of the concrete mass to its surface. Using the strength -maturity relationship developed for the approved concrete mixture, determine the in -place concrete compressive strength.

(a)Class HPC(O). Wet cure the concrete for at least 1 4 days. Provide internal cooling, external heating, or insulation to ensure the temperature differential does not exceed 35 °F. Cure until the in-place concrete compressive strength of the overlay concrete attain s at least 80 percent of the minimum compressive strength shown in Table 569-1.

(b)Class LMC. Wet cure the concrete for at least 48 hours and until the maturity meter reading exceeds 48 maturity hours. Air cure the concrete for an additional 48 hours and until the maturity meter reading exceeds 9 6 maturity hours. After curing, visually inspect the overlay for cracking or other damage and inspect for delamination. Perform bond test. Remove and replace delaminated or unbounded portions of the overlay or portions damaged by precipitation or freezing. Clean staining or efflorescence to provide a uniform color to the concrete overlay surface.

569.17Texturing. After the bond strength shown in Table 569-1 is attained, groove surface according to Subs ection 552.14(g) . Continuously remove slurry and other residue from the overlay by vacuum pickup or other approved methods. Properly dispose of slurry and other residue off site.

569.18Acce ptance. See Table 569-2 for sampling, testing, and acceptance requirements. Material for concrete overlays for bridge decks will be evaluated under Subsections 106.02 and 106.03. Submit a production certification with each shipment of cementitious material. Bond strength will be evaluated under Subs ection 106.05. The lower specification limit is the minimum required bond strength at 14 days shown in Table 569-1. Compressive strength will be evaluated under Subs ection 106.05. The lower specification limit is the minimum required compressive strength at (f' c) 28 days shown in Table 569-1. Maximum chloride permeability will be evaluated under Subs ection 106.05 . The upper specification limit is the maximum specified chloride permeability value shown in Table 569-1. A single chloride permeability test result is the average result from 2 samples cast from the same load and tested. Slump, air content, density, and temperature will be evaluated under Subs ections 106.02 and 106.04. Construction of concrete overlays for bridge decks will be evaluated under Subsections 106.02 and 106.04. Concrete repairs will be evaluated under Section 572. Hydrodemolition will be evaluated under Section 560. Micro milling will be evaluated under Section 413.

Measurement

569.19Measure the Section 569 pay items listed in the bid schedule according to Subs ection 109.02 .

Payment

569.20The accepted quantities will be paid at the contract price per unit of measurement for the Section 569 pay items listed in the bid schedule, except the overlay concrete contract price will be adjusted according to Subs ection 106.05. Payment will be full compensation for the work prescribed in this Section. See Subs ection 109.05. Payment for overlay concrete will be made at a price determined by multiplying the contract price by the lower of the three pay factors determined for compressive strength, chloride permeability, or bond strength. Table 569-2 Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Source

Aggregate

(fine & coarse ) Measured & tested for conformance (106.04 & 105) Quality − Subsections

703.01&

703.021 per material type Source of material Yes, if requested Before producing Date reports within 1 year of intended use

Mix Design

Concrete

composition Measured & tested for conformance (106.04 & 105) All − Subsection

569.041 per mix design Source of material Yes, if requested Before producing − Production Start -up (Test Section ) HPC(O) Measured & tested for conformance (106.04 ) Maximum chloride permeability(1) − AASHTO T 277 1 set per test placement Discharge stream at point of placemen t(1) Yes, if requested Upon completing tests −

Compressive

strength(2) − AASHTO T 23 & 22 " " " " −

Tensile bond

strength − ASTM C1583 5 cores per test placement In-place after curing is complete " " − Table 569-2 (continued) Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Production Start -up (Test Section ) (continued)

LMC Measured &

tested for conformance (106.04 ) Maximum chloride permeability(1) − AASHTO T 277 1 set per test placement Discharge stream at point of placement Yes Upon completing tests −

Compressive

strength(3) − AASHTO T 23 & 22 " " " " −

Tensile bond

strength(7) − ASTM C1583 5 cores per test placement In-place after curing is complete " " − HPC(O) and LMC " Density(4) − AASHTO T 121 1 per load Point of discharge No Upon completing tests − Air content(4) − AASHTO T 152 or

AASHTO

T 196 " " " " − Slump(4),(5) − AASHTO T 119 " " " " − Temperature − Field measured " " " " − Table 569-2 (continued) Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Production Start -up (Test Section ) (continued)

Aggregate

(fine & coarse) Measured & tested for conformance (106.04 ) Gradation − AASHTO T 27 & T 11 1 per day Flowing aggregate stream (bin, belt, discharge conveyor belt, or stockpile) Yes Before batching −

Fineness

modulus − AASHTO T 27 − " " " − Moisture test − AASHTO T 255 − " " " −

Production

HPC(O) & LMC Statistical (106.05) Maximum chloride permeability(1) II AASHTO T 277 1 set per 30 yd3 but not less than 1 per day Discharge stream at point of placement Yes Upon completing tests −

Compressive

strength(6) II AASHTO T 23 & T 22 " " " " −

Tensile bond

strength(7) II ASTM C1583 1 set per 3000 ft2 of overlay but not less than 1 per day In-place after curing is complete No " − Table 569-2 (continued) Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Production (continued) HPC(O) &

LMC Measured &

tested for conformance (106.04 ) Density(4) − AASHTO T 121 1 per load Point of discharge No Upon completing tests − Air content(4) − AASHTO T 152 or

AASHTO

T 196 " " No " − Slump(4),(5) − AASHTO T 119 " " " " − Temperature − ASTM C1064 " " " " −

Aggregate

(fine & coarse) Measured & tested for conformance (106.04 ) Gradation − AASHTO T 27 & T 11 1 per day Flowing aggregate stream (bin, belt, discharge conveyor belt, or stockpile) Yes, if requested Before batching −

Fineness

modulus − AASHTO T 27 − " " " − Moisture test − AASHTO T 255 − " " " − Table 569-2 (continued) Sampling, Testing, and Acceptance Requirements

(1)Cast at least three 4 - by 8-inch maximum chloride permeability cylinders per set and carefully transport the cylinders to the job site curing facility. Cure the HPC(O) cylinders for 7 days and the LMC cylinders for 3 days according to AASHTO M 201. Then cure the HPC(O) cylinders at 100± 10 °F in saturated lime water until AASHTO T 277 sample conditioning starts and air dry the LMC cylinders at 73 ±3 °F at 40 to 60 percent relative humidity. Test for chloride permeability at 28 days by m easuring the total charge passed, in coulombs, over a sp ecified period of time according to AASHTO T 277. The test result is the average of the measurements on three cylinders cast from the same load. If pigment is used in the concrete mixture, sample concrete at the batch plant before and after adding pigment. Test at least three specimens with and without pigment. Determine the average difference between the pigmented and non -pigmented test results. Adjust production test results by the average difference. Report both initial and adjusted test results.

(2)For HPC(O), cast at least fifteen 4 - by 8- inch compressive strength cylinders per set and carefully transport the cylinders to the job site curing facility. Test three cylinders each at 1, 3, 7, 14 and 28 days. A single compressive strength test result is the average result from three cylinders cast from the same load.

(3)For LMC, cast at least eighteen 4 - by 8-inch compressive strength cylinders per set and carefully transport the cylinders to the job site curing facility. Test three cylinders each at 1, 2, 4, 7, 14 and 28 days. A single compressive strength test result is the average result from three cylinders cast from the same load.

(4)For LMC, measure density, slump, and plastic air content 5 minutes after discharge from the mixer chute. Cover wheelbarr ow or other receptacle used to hold sample with a sheet of plastic to prevent evaporation during the 5 minutes before sampling.

(5)If reinforcing fibers are used at an addition rate greater than 0. 3 percent by volume, measure slump at the batch plant before adding fibers.

(6)Cast at least six 4 - by 8- inch compressive strength cylinders per set and carefully transport the cylinders to the job site curing facility. Test three cylinders at 28 days. Use the remainder of cylinders as directed.

(7)At random locations determined by the CO, core 2- inch diameter specimens through the overlay and ½ inch into the substrate concrete. Cure the specimens in situ for the same length of time as the overlay. Test the specimens in situ by a ttaching a loadin g disk with fast setting, high strength epoxy. Measure the tensile pull -off bond strength in pounds per square inch according to ASTM C1583. The average bond strength is the average of the results from three test specimens adjusted as follows: For tests wh ere failure occurs in the substrate concrete at a depth of at least ¼ inch for more than 50 percent of the specimen, use 150 pounds per square inch for that specimen test result in the calculation of the average of the three test specimens. When two of the three test results have been adjusted, the average bond strength results use the greater of 150 pounds per square inch or the calculated value.