Section 501 — Minor Concrete Pavement

Description

501.01This work consists of constructing minor concrete pavement on a prepared surface.

Material

501.02Conform 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 Reinforcing steel 709.01 Sealants, fillers, and seals 712.01 Water for cementitious materials 725.01(a)

Construction Requirements

501.03Composition (Concrete Mix Design). Design and produce concrete mixtures that conform to Table 501-1. Submit concrete mix designs for approval at least 30 days before production.

(a)Concrete pavement. Include the following in each mix design submittal:

(1)Type and sources of material;

(2)Material certification for material;

(3)Saturated surface dry mass of the fine and coarse aggregate per cubic yard of concrete;

(4)Gradation of fine and coarse aggregate;

(5)Fine and coarse aggregate quality;

(6)Water content in pounds per cubic yard of concrete;

(7)Water to ce mentitious material ratio. The water to cementitious material ratio for concrete is the ratio of the mass of water to the combined masses of hydraulic cement and cement substitute;

(8)Cement content in pounds per cubic yard of concrete. Pozzolans, ground iron blast -furnace slag, or silica fume may be substituted for cement according to Table 552-2;

(9)Type and dosage of admixtures and reinforcing fibers used;

(10)Target values for concrete air content;

(11)Target values for concrete slump; 426 (12) Concrete density;

(13)Compressive strength test results at 28 days according to Table 501-2, Note (1) & (4); and

(14)Material samples, if requested.

(b)Integral colored admixture. If integral color admixture is used, prepare five, 2 - by 2- foot test panels. Construct the test panels using the approved mix design. Determine coloring agent batch amounts by weight. Use variable quantities of coloring agent as approved. Provide additional mixing time according to the manufacturer ’s recommendations. Cure the test panels according to Subsection 501.10. Transport the panels to an approved loc ation. Provide at least 2 weeks outside exposure. The CO will select the acceptable test panel. Use the same rate of integral color admixture for the item of work. Table 501-1

Composition of Concrete

Maximum

Water/

Cementitious

Material

Ratio Maximum

Slump

AASHTO

T 119, inch Minimum

Air Content ,

percent Maximum

Coarse

Aggregate

Size

AASHTO M 4 , inch(1) Minimum 28-Day

Compressive

Strength

AASHTO T 22 , pounds per square inch 0.45 4 (fixed form) 5.0 1½ 4000

(1)Meet size number gradation and requirements from AASHTO M 43 for coarse aggregates. Blending of standard sizes to optimize gradation is allowed.

501.04Equipment. Conform to the following:

(a)Forms. Provide straight, steel forms. For curved edges with radii less than 150 feet, provide flexible or curved forms. Provide forms conforming to the following:

(1)Height equal to the pavement thickness at the edge;

(2)10-foot minimum length;

(3)Stabilizing devices to secure form to the prepared surface and to withstand paving operations and pressure of concrete with no visible movement or settlement;

(4)Joint locks to join form lengths tightly together; and

(5)Clean and free of hardened concrete, dirt, distortion, and rust.

(b)Paving and finishing.

(1)Fixed form construction. Provide equipment conforming to one of the following:

(a)Manual finishing machines or roller screeds that can consolidate and finish the concrete ; or 427 (b) Mechanical, self -propelled, finishing machines that can consolidate and finish the concrete with minimal hand finishing. Coordinate the number of driving wheels, power of the motor, and the machine’s mass to prevent slippage. Do not use machines that displace the fixed forms .

(2)Vibrators. Provide internal immersed tube or multiple spud type vibrators for paving more than 8 inches thick. Surface pan type vibrators are acceptable for full -width concrete consolidation of slabs 8 inches or less in thickness. Operate the vibrators at frequencies within 5000 to 8000 vibrations per minute, unless otherwise recommended by the manufacturer. Provide a tachometer for measuring vibration frequencies. Attach vibrators to the spreader or finishing machine or mount on a separate carriage that precedes the finishing machine. For construction of irregular areas, use hand -held vibrators operated at a frequency recommended by the manufacturer.

(3)Floats. Provide mechanical or hand -operated floats designed to finish pavement surfaces uniformly smooth.

(c)Concrete saws. Provide concrete saws that can saw new concrete for crack control to the required depth and alignment. Equip saws with blade guards and devices to control alignment and depth. Maintain a sufficient supply of replacement blades during sawing operations.

(d)Joint sealing. Provide sealing equipment according to the sealant manufacturer’s recommendatio ns.

501.05Production Start -Up Procedures. At least 7 days before the start of concrete placement operations, conduct a pre -concrete pavement preparatory phase meeting according to Subsection 153.06(a) . Coordinate attendance with the CO and applicable subcontractors. Submit and be prepared to discuss the following:

(a)Proposed pour sequence and placement schedule;

(b)Approved concrete mix design;

(c)QCP including technicians responsible for QC and batch tickets at the mixing plant and technicians responsible for QC, sampling, testing, and discharge at the project site;

(d)Equipment, batching, mixing, placing, and curing requirements;

(e)Subsections 106.03 and 106.04;

(f)Jointing plan, joint forming or sawing operations, precipitation protection plan, hot and cold weather paving plan, and opening to traffic requirements; and

(g)Temporary traffic control plan.

501.06Surface Preparation, Setting Forms, and Steel Reinforcement. Maintain the roadbed surface according to Subsection 301.07. Maintain the surface to avoid the development of loose and uncompacted material. Set and align forms to the plan dimensions and elevations and ensure there is no bulging or warping. Set forms so the entire length of the form is firmly in contact with the grade. Securely brace forms so they 428 will not bulge or warp during concrete placement. Apply form release agent or form oil to the inside form faces. Do not vary the top face of the form from a true plane more than ⅛ inch in 10 feet. Check the alignment and grade elevations of the forms immediately before placing the concrete and make any necessary corrections. Check and correct roadbed surface deformations and rutting exceeding ½ inch and uniformly dampen the surface before placing concrete. Do not start placing concrete material until the forms, reinforcement, and roadbed surface have been approved. Do not remove forms from freshly plac ed concrete until the concrete has set for at least 12 hours. If shown in the plans , place steel reinforcement such as rebar, steel wire fabric, and steel mats according to Section 554. If placing reinforcement before pla cing concrete, position the reinforcement on acceptable supports. Do not use stones, concrete, or wood to support reinforcement. If placing reinforcement after placing concrete, mechanically insert the reinforcement to the required depth. Provide epoxy-coa ted steel reinforcement and steel supports. Keep epoxy- coated steel reinforcement free of damage and distortion.

501.07Placing Concrete. Unless otherwise stated in this subsection, conform to Subsections 552.04 through 552.08 for mixing, delivery, QC, temperature limitations, weather limitations, handling, and placing of concrete. Do not walk in concrete with boots or shoes coated with earth or other contaminants. Deposit concrete between the forms to a uniform height. Deposit concrete to minimize rehandling and deposit without segregating the mix. Perform hand spreading with shovels, not rakes. Consolidate concrete to remove voids and air pockets. Use vibrators to consolidate concrete. Uniformly vibrate the concrete across the full width and depth of the pavement. Do not operate hand vibrators more than 15 seconds, or less than 5 seconds in any one location unless approved. Place vibrators in and withdraw from concrete vertically in a slow deliberate manner. Do not move concrete horizontally with vibrators. Do not allow vibrators to contact reinforcement, load transfer devices, subgrade, and side forms. Strike off and place concrete with a form -riding paving machine or manual fixed form paving equipment. In irregular areas where a paving machine is impractical, place concrete using templates, screeds, or other approved methods. Carry a slight excess of concrete in front of the leading edge of the template or screed. After strike -off and before bleed water appears on the surface, float to the required grade and cross -section. Finish the concrete pavement to minus ¼ inch or plus ⅜ inch of the thickness required. If concrete is placed adjoining a previously constructed lane of pavement , do not operate mechanical equipment on the existing lane until the lane has attained one of the following:

(a)A minimum flexural strength of 450 pounds per square inch according to AASHTO R 100 and AASHTO T 97; or

(b)A compressive strength of 3000 pounds per square inch according to AASHTO T 22 and AASHTO R 100. When precipitation is threatening during paving operations, stop paving operations and protect the concrete pavement from precipitation with plastic sheeting or other approved methods. Remove, replace, or repair pavement damaged by precipitation as approved. 429 501.08 Joints. Construct joints at locations and dimensions shown in the plans. If jointing locations are not shown in the plans, submit a jointing plan according to Subsection 104.06. Show locations of contraction, construction, and isolation joints. Saw joints before uncontrolled shrinkage cracking occurs, but after concrete has hardened sufficiently to prevent excessive tearing or raveling. If necessary, use continuous sawing operations regardless of weather or daylight conditions. Do not saw a joint if a crack occurs at or near the joint location before sawing. Discontinue sawing if a crack develops ahead of the saw. Remove and replace newly placed concrete pavemen t where uncontrolled cracking occurs. Do not vary longitudinal joints more than ½ inch and transverse joints more than ¼ inch from true alignment. If curbs or medians are constructed integral with the pavement, construct transverse joints continuous through the curb or median. Clean joints of deleterious material, including concrete slurry, and protect the joints until sealed. For joints that are saw cut, produce a uniform and straight joint. Saw joints approximately ⅛ inch wide and to a depth of at least o ne-third the thickness of the concrete pavement. Do not ravel the joints while sawing. Saw longitudinal joints immediately after sawing transverse joints. Protect the sawed concrete faces from drying during the curing period. Immediately clean freshly cut sawed joints by flushing with a jet of water under pressure and other necessary tools to remove the resulting slurry from the joint and immediate area. To clean joints, use air compressors equipped with suitable traps that can remov e surplus water and oil from the compressed air. Restore curing membrane disturbed during sawing operations by spraying disturbed areas with additional curing compound.

(a)Longitudinal joints. Where required, place deformed steel tie bars perpendicular to the longitudinal joints on rigidly secured chairs or supports. Along longitudinal construction joints, tie bars may be bent at right angles against the form of the first lane constructed and straightened into final position before placing concrete in the adjacent lane. Repair or rep lace broken or damaged tie bars. Approved two- piece connectors may be used instead of tie bars.

(b)Transverse contraction joints. Where required, place dowel bars through and centered on traverse joints and in the middle of the slab depth. Align and hold dowels parallel to the surface and centerline of the slab by a metal assembly that remains in the pavement and is rigidly secured to the base or subgrade using stakes or nails. Limit deviations from parallel to ¼ inch in the length of the dowel bar. Ensure proper alignment of joint and dowel bar assemblies. Coat each dowel bar with an approved bond breaker. Limit bond breaker coating thickness to 15 mil s. During concrete placement, do not displace the dowel joint assembly. Mark the center location of the dowel bar to facilitate sawing operations.

(c)Construction joints. Construct construction joints only at locations specified at the end of each work shift, and when concrete placement is interrupted for more than 30 minutes. If the quantity of 430 concrete placed forms a slab less than 10 feet long at the time of interruption , remove and dispose of the excess concrete to the last preceding jo int according to Subsections 203.05 and 203.07. Where required, install dowel bars in construction joints according to Subsection 501.08(b) . Use a metal or wooden bulkhead to form the joint, shaped to the pavement cross -section and designed to allow the installation of dowel bars. Set and hold bulkhead firmly in place in a plane at right angles to centerline and perpendicular to the surface of the pavement.

(d)Isolation joints. Form isolation joints around manholes, utility boxes, foundations, other fixed objects, or as shown in the plans. Place a ½-inch pre- formed joint filler continuously around or along each structure that extends into or through the pavement before concrete is placed. After the concrete hardens, recess the joint filler about ¾ inch to allow a reservoir for sealant.

501.09Surface Finishing. Protect the surface from precipitation damage. Float finish the surface. Remove laitance or thin grout. After floating, check the surface of the fresh concrete with a 10- foot metal straightedge. Lap each successive check with the straightedge 5 feet over the previous check path. Correct deficiencies indicated by the straightedge while the concrete is still plastic. Fill depressions with freshly mixed concrete, then strike off, consolidate, and refinish. Cut and refinish high areas. Do not apply water to the surface of the concrete during finishing operations. Before the concrete has initially set, work the p avement edges of isolation joints, transverse and longitudinal construction joints, and emergency construction joints to produce a ¼ inch or less continuous radius and a smooth, dense mortar finish. Do not use mortar buildup to round edges. As soon as excess moisture has disappeared and while the concrete is still plastic enough to make a granular surface possible, texture the surface to produce a skid resistant surface. Use the method specified and conform to the following:

(a)Transverse tine finish. Drag two layers of moistened burlap along the pavement in the direction of paving without tearing or marring the surface. Following the burlap drag, use a tining comb to form grooves in the pavement surface. Space tines randomly ½ to ¾ inch apart. Produce grooves that are ⅟ 16 to 3/16 inch wide and ⅛ to 3/16 inch deep. Tine perpendicular to the centerline without tearing the concrete surface or loosening surface aggregate.

(b)Broom finish. Broom the surface with a steel or stiff -bristled fiber broom to produce corrugat ions between ⅟ 16 and ⅛ inch deep. Broom perpendicular to the centerline from edge to edge with adjacent strokes slightly overlapped. Use the same type and manufacture of broom for all paved surfaces to provide a consistent appearance.

(c)Exposed aggregate fin ish. Broom the surface. Use approved stiff brushes. Exercise care to prevent marring of the surface and cracking or chipping of slab edges or joints. If approved, apply a light spray of retardant to the unfinished surface to facilitate this work. Broom tra nsversely across the pavement. Pull the loosened semi -stiff mortar off the pavement. Remove the mortar from adjacent pavement. Broom parallel to the centerline. Continue this operation until coarse aggregate is exposed. Other methods of aggregate exposure may be used if approved. 431 After curing, wash the surface with water and brush to remove laitance and cement from the exposed coarse aggregate.

501.10Curing Immediately after finishing and when marring will not occur, cure the surface and exposed sides of concrete for at least 72 hours. Do not leave the concrete exposed for more than 30 minutes during the curing period. Cure using one of the following methods:

(a)Water method. Cure according to Subsection 552.13(b) ; or

(b)Liqu id membrane curing compound method. Cure according to Subsection 552.13(c) . Remove forms when the concrete has hardened sufficiently to resist damage, but no earlier than 12 hours after placing concrete. Protect the sides of the exposed slabs with a curing method equal to that provided for the surface. Prevent erosion of the base course beneath the exposed pavement edges until shoulders are constructed.

501.11Sealing Joints. Saw cut and seal joints before the pavement is opened to construction or public traffic. Where sealant reservoirs are required, clean each sealant reservoir of foreign material including membrane curing compound and concrete slurry. Blow dry joints with moisture free compressed air. Do not apply sealin g material unless the joint faces are clean and surface dry, and the joint is free of incompressibles. Use preformed joint seals, silicone sealant, or hot -poured sealant for isolation joints. Use silicone or hot-poured sealants for longitudinal and transve rse contraction joints.

(a)Silicone or hot -poured sealants. Install backer rod with a steel -wheel to the depth required. Do not stretch or twist the backer rod during installation. Limit the length of backer rod installed to that which can be sealed during the same workday. Place joint sealing material when the air temperature is over 40 °F or according to the manufacturer ’s recommendations. Remove excess or spilled material and clean the pavement surface. Do not use sand or similar material to cover the seal. For sealants that are not self -leveling, tool the surface of the sealant to the dimensions shown in the plans.

(b)Preformed joint seals. Provide the seal in one piece in the size specified for the joint opening. Install seals with a lubricant adhesive covering both sides of the joint. Compress the seal to between 20 and 50 percent of its nominal width or according to the manufacturer ’s recommendations. Install the top of the seal about ¼ inch below the pavement surface. Remove and replace seals that are damag ed, twisted, improperly positioned, or stretched more than 3 percent.

501.12Pavement Straightedge Measurement. Measure the pavement surface after the concrete has cured. Use a 10- foot metal straightedge to measure at right angles and parallel to the centerline. Defective areas are deviations between the surface and the bottom of the straightedge more than ¼ inch, measured between two contacts of the straightedge, or deviations more than ¼ inch measured at the end of the straightedge. Correct defective are as by diamond grinding, slab removal, or other approved methods. 432 501.13 Opening to Traffic. Do not allow traffic on new concrete pavement for 3 days and until one of the following conditions is met:

(a)Flexural strength of 550 pounds per square inch according to AASHTO T 97; or

(b)Compressive strength of 4000 pounds per square inch according to AASHTO T 22. Complete testing on samples taken at the same frequency as shown in Table 501 -2 for compressive strength testing. Do not allow traf fic on the pavement when joint sealant is tacky and traffic debris would imbed into the sealant.

501.14Acceptance. See Table 501-2 for sampling, testing, and acceptance requirements. Material for minor concrete pavement will be evaluated under Subsections 106.02 and 106.03. The concrete mixture’s slump, air content, density, temperature, and compressive strength will be evaluated under Subsections 106.02 and 106.04. Construction of concrete pavement will be evaluated under Subsections 106.02 and 106.04. Reinforcing steel will be evaluated under Section 554.

Measurement

501.15Measure the Section 501 pay items listed in the bid schedule according to Subsection 109.02 .

Payment

501.16The accepted quantities will be paid at the contract price per unit of measurement for the Section 501 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 . Table 501-2 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& 703.02 1 per material type Source of material Yes 30 days before paving −

Mix Design

Concrete

composition (501.03 ) Measured & tested for conformance (106.04 & 105) All − Subsection

501.031 per mix design Source of material If requested 30 days before paving − Table 501-2 (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

Concrete Measured &

tested for conformance (106.04 ) Density − AASHTO T 121 1 per load(2) Point of discharge(3) No Upon completing tests − Air content − AASHTO T 152 or T 196 " " " " − Slump − AASHTO T 119 " " " " − Temperature − ASTM C1064 " " " " −

Compressive

strength(1),(4) (28-day) − AASHTO R 100 & T 22 1 set per 200 yd2 but not less than 1 set per day " Yes 28 days Deliver verification cylinders to the CO or designated laboratory for scheduled testing

Aggregate

(coarse & fine) Process control (153.03 ) Gradation − AASHTO T 27 & T 11 1 per day min Bin discharge, conveyor belt, or stockpile No Before batching − Moisture − AASHTO T 255 " " " " − Concrete " Surface tolerance − Straightedge measurements

Subsection

501.07Subsection

501.07Concrete surface, after floating " While concrete is still workable − Table 501-2 (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

Finished Roadway

Concrete

pavement Measured & tested for conformance (106.04 ) Surface tolerance − Straightedge measurements

Subsection

501.12Successively, after concrete has hardened Finished pavement surface No 24 hours −

(1)A single compressive strength test result is the average result from two 6 - by 12 -inch or three 4 - by 8-inch cylinders cast from the same load.

(2)This frequency may be reduced by the CO if produced material proves to be consistent.

(3)Sample according to AASHTO R 60, except composite samples are not required.

(4)Cast at least four 6 - by 12 -inch or six 4- by 8-inch compressive strength test cylinders and transport the cylinders to the project curing facility.