00559.21 533 Section 00559 - Structural Concrete Overlays
Description
00559.00Scope - This Work consists of constructing structural concrete overlays (SCO)
00559.04Preplacement Conferences:
Subcontractors, Suppliers, the quality control technician, the concrete control technician, and all other personnel who will be involved in the resurfacing Work . Meet at a mutually agreed time approximately 2 weeks in advance of the Work . Present and discuss all phases of the resurfacing Work .
resurfacing work crew and the QCT, at the Project Sit e 1/2 hour before resurfacing Work begins to discuss placement duties and procedures. Do not begin the resurfacing Work until this meeting is held.
Materials
00559.10Materials - Furnish Materials meeting the following requirements:
00559.11Class of Concrete - Furnish class HPC4500 - 3/4” according to Section 02001 unless
otherwise shown.
00559.12Quality Control - Provide quality control according to Section 00165
00559.13Acceptance of Concrete - Acceptance of concrete will be according to Section 00165
Equipment
00559.20Equipment - Remove all Equipment that leaks oil or other contaminants from the work
area until they are repaired.
00559.21Finishing Equipment - Furnish a concrete finishing machine for all new surfaces that is:
Self-propelled with positive control in both forward and reverse direction. Capable of mechanically raising the screed, pan, and any other parts of the finishing mechanical operation to clear the screeded surface, and capable of automatically returning to the specified grade. Equipped with augers, followed by oscillating, vibrating screed, vibrating roller tamper, or a vibratin g pan, followed by a finish roller or rollers. Capable of transmitting vibration at frequencies between 3,500 and 4,500 impulses per minute. Provide continuous supporting rails for the finishing machine that are adequately supported and sufficiently rigid so there is no visible deflection under the weight of the fully loaded machine. Provide anchorage for the supporting rails to ensure horizontal and vertical stability.
00559.22 534 Set the finishing machine so it is capable of finishing to the edge of previously pla ced concrete.
Set the screed rails on the completed lane surface when placing concrete in a lane abutting a previously completed lane.
00559.22Miscellaneous Equipment :
with approved vibrators attached to consolidate and finish smaller areas where it is impracticable to use a finishing machine. Use spud vibrators when depths exceed 2 1/2 inches. Use supplemental vibration along the meet lines where a djacent pours come together at bulkheads, and along curb lines, unless it can be shown that vibration reaches the meet lines.
in diameter.
• Is compatible with the core tested. • Can exert a tensile l oad to the core sufficient to exceed 300 psi. • Is equipped with a measuring device capable of reading tensile force exerted within 1 percent accuracy.
ahead of the concr ete placement.
Labor
00559.30Quality Control Personnel - Provide certified technicians according to 02001.50
Construction
00559.41Surface Preparation - Perform surface preparation according to Section 00504
00559.42Plac ement Conditions - Place structural concrete overlays according to 00540.49 and the
following:
The surface temperature of the prepared deck is 40 °F or greater and less than 80 °F. The surface temperature is rising if it is between 40 °F and 45 °F. In the presence of the Engineer, measure the surface temperature with an infra-red thermometer at a minimum of three locations on the deck.
00559.43Handling and Placing Concrete :
shown.
Control sagging or running of freshly placed concrete in areas of steep gradient by one or both of the following methods: 00559.45 535 • Modifying direction or method of placement • Modifying slump
Except when allowed, keep traffic off the lane adjacent to a placement for at least 4 hours after the placement is completed. When allowed, slow traffic by flagging for at least 4 hours after completion of the pour. In both cases, the Engineer may increase the time limits due to weather or traffic conditions.
finishing machine for structural concrete overlays .
in the presence of the Engineer, over the deck to check that the required thic kness of concrete overlay will be achieved. Place concrete working up- grade, unless otherwise approved.
a straight, vertical edge before placing any adjacent sections. Sawcutting joints may be omitted if the bulkhead produces a straight, smooth, vertical surface. On both sawcut and formed joints remove all loose material by sand blasting or water blasting the face of the joints.
joints will only be allowed as shown or approved by the Engineer.
construction joint by removing all material not up to finish grade, in a straight line.
broom a thin coat of grout onto the prepared deck. Ensure that all parts of the prepared deck receive a vigoro us brooming that scrubs the grout into the deck surface and results in an even coat with no excess grout collecting in pockets. Do not extend grout placement more than 15 feet ahead of the overlay being placed. Grout shall be a mixture of water and cement with a w/c ratio of between 0.45 and 0.50. Broom the grout at a rate to prevent dry ing before being covered by the overlay . If the grout does dry, stop the overlay , remove the dried grout, clean and prepare the affected area of the deck , and reapply grout according to this Subsection .
Stop all placement operations if it starts to rain. Protect fresh previously placed concrete from rain. The Engineer may order removal of all concrete damaged by rain.
horizontally with water according to 00540.28 and float it, only if necessary, to produce a smooth, uniform, sealed surface. Do not spray water dir ectly on the freshly placed concrete and do not allow water to puddle or pond. Hand finishing may be required along edges of concrete placement. Use a 12 foot straightedge during placement to verify deck grades and to correct defects in hand finished areas. The finished surface, when tested with a 12 foot straightedge, shall not vary by more than 1/8 inch. If the concrete surface does not meet the surface tolerance, stop the operation until revised methods, changes in Equipment, or correction of procedures are proposed and approved.
00559.44Curing Concrete - Wet cure structural concrete overlays according to 00540.51 for a
minimum of 7 D ays.
00559.45Bond Strength Test - Perform two bond tests for each placement in the presence of and
at locations desig nated by the Engineer within 28 Calendar Days of overlay placement and before opening the Roadway to traffic. Cut 3 inch diameter cores and conduct bond tests on the cores. 00559.46 536 The bond tests consist of:
Coring through the overlay and approximately 1 inch into the existing concrete. Attaching a device to the top of the core. Exerting a tensile load to the core sufficient to cause failure or achieve 300 psi, whichever occurs first. Avoid taking cores in wheel lines.
A successful test is the failure of the concrete substrate or bond failure at or above 175 psi.
After coring and testing, restore the area voided by the cores by blowing with compressed air and filling with an approved PCC repair Material.
00559.46Delamination Inspection:
of the Engineer, using chain drag or other approved methods.
Repair all delaminated areas of 1 square foot or greater. Delaminated areas of less t han 1 square foot will not require repair. Repair limits to be approved by the Engineer.
00559.47Surface Finish and Tolerance :
after curing and before t exturing with a self -propelled diamond grinder. Correct the surface tolerances before opening the Roadway to traffic at no additional cost to the Agency.
7 Calendar Days and correcting non- specification surface tolerances.
00559.48Crack Sealing - The surface will be inspected by the Engineer for cracks
After correcting non- specification surface tolerances and after texturing the deck surface, seal all visible cracks as follows:
In areas where cracks are 10 feet or more apart, seal each crack separately. In areas where the cracks are numerous or are less than 10 feet apart, seal the entire area where the cracks occur.
Seal with a low modulus concrete and crack sealer.
Perform all repair and sealing Work at no additional cost to the Agency. Complete all repair and sealing Work before opening to traffic. If the Bridge is opened to traffic at the Contractor's request before completing repair Work , all additional traffic control to complete the repair Work will be at no additional cost to the Agency.
Maintenance
00559.60Protection of Concrete - Repair or replace any part of the overlay damaged by traffic or
damaged from any other cause before its of ficial acceptance, according to 00170.80. Do not operate construction Equipment or allow Public Traffic on newly placed concrete until the following requirements are met:
00559.90 537 Comply with 00150.60, 00559.45, 00559.46 and 0559.47. The concrete attains a compressive strength of at least 3000 psi as determined by testing at least three cylinders cured according to AASHTO T 23 (field cure) and tested according to AASHTO T 22. The maturity method, AASHTO T 325, may be used to estimate concrete strength for opening Pavement to construction traffic. Install at least two maturity thermocouples for each Day's placement in areas where the maturity method will be used for early opening. Install the thermocouples near the Day's final placement for areas being evaluated for early opening. When the maturity method is used, the Engineer may verify the maturity method with strength specimens. Establish a new strength-maturity relationship if strength specimens deviate more than 10 percent from the maturity -estimated streng ths. Suspend use of the maturity method for opening Pavements to traffic when the strength-maturity relationship deviates by more than 10 percent until a new strength maturity relationship is established. The surface of the concrete is protected from scar ring or abrasion and kept free of stones, loose mortar and other matter apt to be deleterious to the concrete in the paths of Equipment.
Measurement
00559.80Measurement - The quantities of Work performed under this Section will be measured
according to the following:
on the volume basis. The quantities will be determined from the delivery vehicle batch tickets and checked using the yield factor according to AASHTO T 121 ( ASTM C138).
A deduction will be made for M aterial placed and removed beyond saw cuts or formed construction joints.
measured on the area basis. The area will be determined by measuring the actual surface area of the resurfaced bridge deck.
will be the area of each bridge deck or approach slab shown less 16 inches along each curb and 6 inches from joint blockouts and bridge ends . Field measur ement of surface texturing will not be made.
Payment
00559.90Payment - The accepted quantities of Work performed under this Section will be paid for
at the Contract unit price, per unit of measurement, for the following items:
Pay Item Unit of Measu rement
Payment will be payment in full for furnishing and placing all Materials, and for furnishing all Equipment , labor, and Incidentals necessary to complete the Work as specified.