330 Initial sawing of joints shall commence as soon as the concrete has hardened sufficiently to permit sawing without excess raveling, usually 4 to 24 hours. All joints shall be initially sawed before uncontrolled shrinkage cracking takes place, but no later than 24 hours after placement of concrete. 601.8.9 -Stay-in-Place Fabricated Metal Forms f or Concrete Bridge Decks: All concrete bridge decks shall be constructed with a stay -in-place fabricated metal forming system per the requirements shown in this specification unless otherwise noted in the plans. 601.8.9.1 -General: Stay-in-place fabricated metal forms for concrete deck slabs of bridges shall be used on all interior bays of beams. For overhangs and where longitudinal expansion joints are located between stringers removable forms shall be used. The design and material of the forms, in the judgment of the Engineer, shall be such as to give an expected maintenance free service life equal to the service life of the concrete slab. The stay - in-place fabricated metal forms shall be crimped at each end. Unless otherwise spe cified in the plans, the weight of stay -in-place fabricated metal forms plus concrete in the form flutes used in the design is 15 psf. The contractor shall submit revised computations if the proposed forming system is heavier than 15 psf. The cost of the revised computations shall be at no additional cost to the Division. 601.8.9.2 -Material: Stay-in-place fabricated metal forms for concrete decks slabs and exposed material for supports shall be zinc -coated (galvanized) steel sheet conforming to ASTM A6 53, Designation SS, Grades 33 through 80, with a G165 Coating Designation. The stay -in-place fabricated metal forms shall be designed on the basis of dead load of the forms, reinforcement, and the plastic concrete plus 50 psf for construction loads. Unit working stresses shall be in accordance with the AASHTO LRFD Bridge Design Specifications for construction loads and the unit stress in the steel sheet shall be not more than 0.725 of the specified minimum yield strength of the material furnished but not to exceed 36,000 psi. Maximum deflection under weight of plastic concrete, reinforcement and form shall not exceed 1/180 of the form span or ½ inches , whichever is less. Maximum deflection under 60 psf of live loads shall not exceed 1/360 of the form spa n or ¼ inches , whichever is less. The form span for design and deflection shall be the clear distance between the flanges of the supporting beams less two ( 2) inches, measured parallel to the form flutes. All stay -in-place fabricated metal forms shall ha ve a minimum thickness of 22 gage. Physical design properties shall be computed in accordance with requirements of American Iron and Steel Institute Specification for the Design of Cold -Formed Steel Structural members, latest published edition. All reinf orcing bars in the bottom layer of the deck slab reinforcement shall have a minimum concrete cover of 1”. The distance from the top of the slab to the bottom layer of deck slab reinforcement shall not be less than that shown on the plans. 601.8.9.3 -Installation: All forms shall be installed in accordance with detailed fabrication plans submitted to the Engineer for approval. The fabrication plans shall clearly indicate locations where the forms are supported by steel beam flanges. Form s heets shall not be permitted to rest directly on the top of the stringer or floor beam flanges. Sheets shall be securely fastened to form supports and shall have a minimum bearing length of 1” at each end. Form supports shall be placed in direct contact with the flange of 331 stringer or floor beam. All attachments shall be made by bolts, clips, or other approved means. Welding of form supports to flanges shall not be permitted. Any exposed form metal where the galvanized coating has been damaged shall be thoroughly cleaned and wire brushed, and then painted with two coats of zinc -rich primer, conforming to Subsection 711.21, to the satisfaction of the Engineer. Transverse construction joints shall be located at the bottom of a flute and ¼” weep holes shall be provided in the field at 12” 3” on center along the line of the joint. 601.8.9.4 -Placement of Concrete: Concrete shall be placed in accordance with the contract specifications. The entire form shall be filled with deck concrete. No filler materi al shall be permitted. Particular emphasis should be placed on proper vibration of the concrete to avoid honeycomb and voids, especially at construction joints, expansion joints, flutes, and ends of form sheets. The use of covered flutes or fillers of a ny kind in the flutes of the stay -in-place fabricated metal forms is not permitted. Prior to placement of concrete, the Contractor shall submit to the Engineer for approval Concrete Volume to Stay in Place Form Adjustment Factor ( SIP adj). The SIP adj shall be the equivalent ratio of the concrete volume in the form flutes to Square Yard of Stay -In- Place Form Area. 601.8.9.5 -Inspection: The Contractor's method of construction shall be carefully observed during all phases of the construction of the br idge deck. These methods include installation of the Stay -in-place fabricated metal forms; location and fastening of the reinforcement; composition of concrete, placement and vibration; and finishing of the bridge deck. Unless waived by the Engineer, the Contractor shall remove at least one section of the forms at a location and time selected by the Engineer for each concrete placement in each approved pour sequence. This should be done as soon after placing the concrete as practicable in order to provid e visual evidence that the concrete mix and the Contractor’s procedures are obtaining the desired results. An additional section shall be removed each time the concrete mix or the contractor’s procedures are changed, unless waived by the Engineer. After the deck concrete has been in place for a minimum of two days, the concrete shall be tested for soundness and bonding of the forms by sounding on the forms with a hammer at least 50 percent (50%) of the area of at least 25 percent (25%) of the individual f orm panels, as selected by the Engineer on a random basis. If areas of doubtful soundness are disclosed by this procedure, the Contractor will be required to remove the forms from such areas for visual inspection. At locations where sections of the forms are removed, the Contractor will not be required to replace the forms, but the adjacent metal forms and supports shall be repaired to present a neat appearance and assure their satisfactory retention. As soon as the form is removed, the concrete surfaces will be examined for cavities, honeycombing and other defects. If irregularities are found, and in the opinion of the Engineer these irregularities do not justify rejection of the work, the concrete shall be given a Class 1, Ordinary Surface Finish in accordance with the contract specifications and shall be repaired as the Engineer may direct. If the concrete where the form is removed is unsatisfactory, additional forms shall be 332 removed, as necessary, to inspect and repair the slab, and the Contractor's methods of construction shall be modified as required to obtain satisfactory concrete in the slabs. The amount of sounding and form removal may be moderated, at the Engineer's discretion, after a substantial amount of slab has been constructed and inspect ed if the Contractor's methods of construction and the results of the inspections as outlined above indicate that sound concrete is being obtained throughout the slabs. The Contractor shall provide all facilities required for the safe and convenient condu ct of the Engineer's inspection procedures. 601.8.9.6 -Forming System Changes: The contractor shall not utilize a removable forming system without the submittal of the following information:
1.Revised camber tables based on actual forming system.
2.Revised dead load deflection tables based on actual forming system. These revised drawings must be stamped by a West Virginia Professional Engineer and approved by the Engineer prior to commencing forming. No change in unit prices, or contract completion date will be permitted for the use of a removable forming system. 601.8.10 -Architectural Formwork: 601.8.10.1 -General: This work includes additional requirements for the forming of cast-in-place structural concrete designated as architectural . The s cope of this work is as indicated and as detailed on the drawings. 601.8.10.2 -Submittals: The following shall be submitted to the Engineer for his review:
A.Product data and installation instructions for manufactured form systems, form liners, release agents, ties, and accessories. The release agent manufacturer shall certify that the products supplied comply with regulations controlling the use of volatile organic compounds (VOC's).
B.Shop drawings for fabrication and erection. These drawings sha ll show all items that visually affect the exposed concrete, including, but not limited to, general form construction, jointing, specially formed joints or reveals, and patterns of placement. The Engineer’s review will be for general architectural applicat ions and features only. Formwork design for structural stability and sufficiency is the Contractor's responsibility and shall not be submitted for the Engineer’s review.
C.Mockup or Sample Panels. The Contractor shall submit a mockup or sample panel of their respective material indicating texture, finish, and pattern in accordance with Section 601.8.10.3.A. This Mockup or Sample Panel shall have a minimum front surface area of 15 ft2. 601.8.10.3 -Quality Assurance:
A.The Contractor shall construct a mockup or sample panel using the proposed formwork and facing materials in order to demonstrate the required finishes and textures. Actual construction of architectural concrete shall not proceed until the Engineer has accepted the sample units.
B.Before placing conc rete, the Contractor shall check lines and levels of erected formwork, and shall make corrections and adjustments to ensure:
1.proper size and location of concrete members
2.stability of the forming systems 333 C. During concrete placement, the Contractor shall chec k formwork and related supports to ensure the forms are not displaced and that completed work will be within specified tolerances. 601.8.10.4 -Materials: 601.8.10.4.1 -Form Materials:
A.Forms for Exposed -Finish Concrete: Unless otherwise indicated, construct formwork for exposed concrete surfaces with plywood, metal, metal -framed plywood -faced or other paneled materials to provide as -cast surfaces. Furnish in largest sizes to minimize number of joints and to conform to joint system shown on drawings. Provide form materials with sufficient thickness to withstand pressure of placed concrete without bow or deflection beyond allowable tolerances.
1.Use overlaid plywood, APA grade trademarked "High Density Overlay (HDO)."
2.Use plywood, APA grade trademarked "B -B Plyform Class 1."
B.Forms for Textured Finish Concrete: Provide special forming materials to produce surfaces with face design, texture, arrangement, and configuration as shown on drawings or as required to match Engineer's control sample. Provide solid backing and form supports to ensure stable textured form liners.
C.Form Coating: Provide a commercial formula release agent that will not bond with, stain, or adversely affect concrete. Provide material that will not impair subsequent treatm ent of concrete surfaces requiring bond or adhesion, nor impede wetting surfaces to be cured with water or a curing compound. 601.8.10.4.2 -Formwork Design: Design formwork for easy removal without impact, shock, or damage to the concrete and adjacent ma terials. 601.8.10.5 -Construction Methods: 601.8.10.5.1 -Form Construction:
A.General: Construct forms to sizes, shapes, lines, and dimensions shown, and as required to obtain accurate alignment, location, level, and plumb work in finished structures. Pro vide for openings, offsets, keyways, recesses, chamfers, blocking, screeds, bulkheads, and other as required.
B.Fabricate forms to prevent cement paste from leaking while placing concrete and for easy removal without hammering or prying against exposed concr ete surfaces. Provide crush plates where stripping might damage cast concrete surfaces. Provide top forms for inclined surfaces where slope is too steep to place concrete. Solidly butt joints and provide backup material at joints to prevent leakage and fins. Assemble forms so that they may be easily removed without damaging exposed concrete surfaces
C.Provide temporary form openings where inaccessible formwork interior can be cleaned and inspected before placing concrete. Place temporary form openings as inconspicuously as possible, consistent with project requirements.
D.When drilling forms used for exposed concrete, drill from the contact face to the outside to suit the ties used and to prevent leakage of concrete mortar. Do not splinter the forms by drivi ng ties through improperly prepared holes.
E.Unless otherwise shown in the plans, 334 1) provide sharp, clean corners at intersecting planes with no visible edges or offsets.
2.provide accurately formed chamfered corners using ¾ x ¾ inch strips, surfaced to produce uniformly straight lines and tight edge joints. 601.8.10.5.2 -Form Coatings:
A.General: Coat form contact surfaces with form -release agent before placing reinforcement. Do not allow excess material to accumulate in forms or to come into contact wi th reinforcement or surfaces that will be bonded to fresh concrete. Apply coating according to manufacturer's instructions.
B.Coat steel forms with non -staining, rust -preventative release agent, or otherwise protect from rusting. Rust -stained steel formwor k is not acceptable. 601.8.10.5 .3-Reusing Forms: Split, frayed, delaminated, or otherwise damaged form -facing materials are not acceptable. Clean and apply a new form -release agent to concrete contact surfaces. 601.9 -ADVERSE WEATHER CONDITIONS : 601.9.1 -Cold Weather Concreting: The plastic concrete shall have a temperature of at least 50F but not more than 85 F at the time of placing. When the plastic concrete has a temperature of less than 55F, the provisions for cold weather concreting shall apply. Maintenance of at least the minimum temperature shall be accomplished by heating the water or the aggregates, or both, as necessary. Heating methods which alter or prevent the entrainment of the required amount of air in the concrete shall not be used. Heating equipment shall be capable of heating the materials to achieve the specified temperature of the plastic concrete. The temperature of the aggregates or water shall not exceed 150 F at the time the cement is added to the mixture. Materials containing frost or l umps of frozen materials shall not be used. If the Contractor is placing concrete or plans to place concrete during cold weather conditions, the Contractor shall advise the D ivision of his plans for curing and protecting the concrete. The Division may at any time, require the Contractor to provide additional protection to cause the provisions of this specification to be met. Stockpiled aggregate may be heated by the use of d ry heat or steam. Aggregates shall not be heated directly by gas or oil flame or on sheet metal over fire. Binned aggregates may be heated by steam -coil or water -coil heating. The use of live steam on or through binned aggregate will not be permitted. The use of calcium chloride to hasten the initial set of structural concrete will not be permitted. Insulated forms may be used for protecting and curing concrete. There will be no additional cost to the Division for the use of insulated forms. Class H or Class K Concrete Cold Weather Provisions: Cold weather periods shall be defined as those periods when temperatures above 50° F do not occur for more than half of any 24 hour duration. The temperature of the surface on which the concrete is to be p laced shall not be less than 45° F immediately prior to placement of the concrete. During the cold weather periods, as defined above, the temperature of the concrete immediately after placement shall be between 55 and 75°F. 601.9.2 -Hot Weather Concreti ng: The Contractor will be required to state, at the pre - construction conference, his plan of action when the temperature of plastic concrete reaches 90F. When a free air, shaded thermometer in the vicinity of the concrete production plant reaches 85 F, thermometer readings of the temperature of the plastic concrete shall be taken at least hourly. When the temperature of the plastic concrete reaches 85 F, the elapsed time between the introduction of the mixing water to the cement -aggregates and discha rge of the mix shall not exceed 1 hour. At this temperature or above, particula r attention shall be paid to the Specification provisions concerning the sprinkling and wetting of surfaces not oil -treated, the maintenance of coarse aggregate stock in satura ted surface -dry condition, and the prompt start of concrete curing operations. When the temperature of the plastic concrete reaches 90 F, immediate steps shall be taken to cool either mixing water or aggregates, or both, in order to maintain a plastic co ncrete temperature of 90 F or less. Crushed or flaked ice may be used to cool t he mixing water. Crushed or flaked ice may also be introduced into the mixing drum when the concrete is batched and mixed in a truck mixer. The ice will be considered as part of the mix water in the mix proportions. The mixing operation shall not be considered complete until all ice in the drum has melted. In no event shall concrete be placed when its temperature in the plastic state at the completion of mixing exceeds 90 F. Bridge Decks: The Contractor's plan of action for all bridge deck concreting operations shall contain provisions designed to minimize the probability that any bridge deck concrete will be placed when the ambient temperature is greater than 85 F.
601.10 Placing Concrete :
601.10.1 General: Concrete shall not be placed until forms and reinforcing steel have
been inspected and approved. The forms shall be cleaned of all debris immediately prior to placing concrete, and surfaces not oil treated shall be wetted. The method and sequence of placing concrete will be subject to approval by the Engineer. Concrete shall be placed so that no segregation will occur and no displacement of reinforcement will be caused. Concrete shall be placed in the forms as nearly as practical in its final position in order to avoid rehandling, and an approximately horizontal surface of the plastic concrete shall be maintained. After initial set of the concrete, the forms shall not be jarred and no strain shall be placed on the ends of projecting reinforcement. Co ncrete shall not be placed until all laitance which may have formed on concrete previously placed, or any loose deleterious material on reinforcing bars, has been removed.
601.10.1 1 -Pre-Pour Meeting: On projects for which the concrete is being used in
bridge construction, the Contractor shall schedule a meeting prior to the start of the concrete work. The Engineer, Construction Manager, Prime Contractor, Concrete Contractor, Concrete Finisher, Concrete Supplier, and the Individual or Agency that wil l perform the quality control testing of the concrete shall attend. Topics of discussion shall include concrete mixture proportions, batching, transporting, handling, placing, finishing, curing, and on -site quality control testing requirements.
601.10.1 2-Concrete Placement Limitations: Immediately prior to, and during,
placement of Class H concrete, if the evaporation rate exceeds 0.10 lb./sq. ft. per hour (see Figure 1), the Contractor shall make provisions (i.e. wind breaks, fogging, etc.) to reduce the rate prior to placing concrete. These provisions shall be maintained during the placement of the concrete. If the evaporation rate obtained from Figure 1 is close enough to the maximum allowable value of 0.10 lb./sq. ft. per hour that there may a disc repancy in the exact numerical value, the following equation shall be used to obtain a more accurate value. E = [T c2.5 – (r x T a2.5)] [1 + 0.4V] x 10-6 Where: E = evaporation rate, lb/ft2/h Tc = concrete temperature, °F Ta = air temperature, °F r = (relative humidity %) / 100 V = wind velocity, mph Example: Air Temperature = 65 °F Relative Humidity = 45% Concrete Temperature = 60 °F Wind Velocity = 20 mph Result Using Figure 1: Evaporation Rate ≈ 0.11 lb/ ft2/h Result Using Formula: E = [Tc2.5 – (r x T a2.5)] [1 + 0.4V] x 10-6 E = [602.5 – (0.45 x 652.5)] [1 + (0.4 x 20)] x 10-6 E = [27885 – 15328] [1 + 8] x 10-6 E = 12557 x 9 x 10-6 E = 0.11 lb/ ft2/h
601.10.1 3 -Concrete Placement at Night: If placement of any concrete is to be made at night,
a plan which provides adequate lighting for the work area shall be submitted at least 14 days before concrete is placed for the Engineer's approval.
601.10.2 Chutes and Troughs: Concrete shall not be dropped in the forms a greater
distance than five (5) feet without the use of closed chutes or pipes. When chutes or troughs are used under steep slope conditions, they shall be equipped with baffle boards or sh all be used in short lengths to reverse the direction of movement. All chutes, troughs or pipes shall be kept clean and free of hardened concrete by flushing with water after each run. Flushing water shall be discharged outside the forms. Aluminum chute s, troughs or pipes shall not be used.
601.10.3 Vibrating: Concrete shall be compacted by the operation of approved
mechanical vibrators within the concrete. When required, vibrating shall be supplemented by hand spading to assure proper compaction, to force all coarse aggregate from the surface, and to bring m ortar against the forms to produce a smooth finish. Vibrators shall be manipulated in such a manner that concrete is worked around reinforcement and imbedded features and into angles of the form. Vibration shall be of sufficient duration to accomplish co mpaction but shall not be prolonged to the point where segregation occurs. Vibration shall not be used to cause concrete to flow from point to point within forms. The frequency of the vibrators shall meet the requirements of Section 501.5.5.
601.10.4 Placing Concrete Bridge Decks: Concrete for bridge decks shall be placed and
finished with mechanical equipment, as outlined in Section 601.5.5, unless waived by the Engineer. The Contractor shall furnish the Engineer information as to the weight of the proposed machine, the volume of concrete to be placed per hour, and the operating procedure to be followed. Where beam support screeds are used and the distance between the support and gutter line is in excess of one ( 1) foot, the Contractor shall use devices to control the grade of the gutter line during the deck finishing operations.
601.10.4 1 -Fogging Equipment: When Class H concrete is used, fogging equipment shall
be available for use in accordance with these specifications. The fogging nozzles shall produce an atomized mist. Fogging nozzles shall incorporate compressed air to crea te the mist. Hand held or hand operated equipment shall be permitted when the Contractor has demonstrated that his operator has been trained in its use.
601.10.4 2 -Placement: The following requirements shall apply during placement of the
Bridge Deck conc rete:
a.So that the use of hand tools will be kept to a minimum, concrete shall be deposited as nearly as possible to its final position. Internal vibrators shall not be used for moving concrete into position.
b.A pencil type vibrator shall be used along all c onstruction joints to further consolidate the concrete to prevent voids.
c.The new concrete shall be placed slightly above final grade. It shall then be struck -off, screeded, and finished to final grade.
d.The finished surface, before texturing, shall be unifo rmly smooth, dense and even. Variations in pavement surface in excess of 1/8 inch above, or below, the proper finished elevation, or surface irregularities of more than 1/8 inch in ten (10) feet, will not be accepted.
e.A construction dam, or bulkhead, shall be installed in case of a delay in the placement operations exceeding 30 minutes duration. During any delays of 30 minutes or less, the placement shall be protected from drying with several layers of wet burlap. If the concrete placement is stopped, or de layed, for 90 minutes or more, further placement shall be discontinued and may be resumed only after the concrete has cured. This restriction does not prohibit continuation of the placement provided a gap is left in the placement. This gap shall be suffici ent in length to allow the finishing machine to clear the previously placed concrete. 339 f. Adequate precautions shall be taken to protect freshly placed concrete from rainfall. All placement operations shall stop when it starts to rain. The Engineer may order removal and replacement of material damaged by rainfall.
g.The addition of superficial water to the surface of the concrete to assist in finishing operations will not be permitted.
601.10.5 Depositing Concrete Under Water: Concrete shall not be placed until all
laitance which may have formed on concrete previously placed has been removed. Still water shall be maintained at the point of deposit. While depositing foundation concrete, pumping shall be discontinued if it res ults in a flow of water inside the forms. All concrete deposited under water shall have the minimum cement content increased at least 10 percent (10%) . Concrete deposited under water shall be carefully placed in a compact mass in its final position by m eans of a tremie, a closed bottom dump bucket, or other approved method and shall not be disturbed after being deposited.
601.11 Finishing Concrete Surfaces :
The surface of the concrete shall be finished immediately after form removal. The exposed surfaces of bridge parapets, wingwalls, headwalls and vertical edge of the bridge deck shall be given a Class 2, Rubbed Finish, or a Class 1, Ordinary Surface Finish supplemented with wood float rubbing. When the Class 1, Ordinary Finish is used, the forms shall be removed as early as practical, not to exceed six hours (in lieu of 601.8.7) after placing, an d the finish completed including rubbing with a wood float and water. The rubbing shall produce a nonplastered, smooth textured and uniform color surface. Other concrete surfaces except bridge decks shall be given a Class 1, Ordinary Finish. Unless othe rwise shown in the plans, all concrete designated as architectural shall receive a Class 1, Ordinary Surface Finish, as defined in Section 601.11.1.
601.11.1 Class 1, Ordinary Surface Finish: Immediately following the removal of the
forms, all fins and irregular projections shall be removed from all surfaces except those which are not to be exposed or are not to be waterproofed. On all surfaces the cavities produced by form ties and all other holes, honeycomb spots, broken corners or edges and other de fects shall be thoroughly cleaned, saturated with water, and carefully pointed and trued with a mortar of cement and fine aggregate mixed in the proportions used in the class of concrete being finished. Mortar used in pointing shall be not more than 30 mi nutes old. The mortar patches shall be cured as specified in 601.12. All construction and expansion joints in the completed work shall be left carefully tooled and free of all mortar and concrete. The joint filler shall be left exposed for its full leng th with clean and true edges. The resulting surfaces shall be true and uniform. All surfaces which cannot be repaired to the satisfaction of the Engineer shall be rubbed as specified for Class 2, Rubbed Finish.
601.11.2 Class 2, Rubbed Finish: After removal of forms, the rubbing shall be started as
soon as the condition of the concrete will permit. The concrete shall be thoroughly saturated with water immediately prior to rubbing and shall be kept saturated throughout the rubbing operation. Suffic ient time shall have elapsed before wetting down to allow the mortar used in pointing to thoroughly set. Surfaces to be finished shall be rubbed with a medium coarse carborundum stone, using a small amount of mortar on its face. The mortar shall be compo sed of cement and fine sand in the same proportion as the concrete being finished. Rubbing shall be continued
Source: West Virginia Standard Specifications for Road and Bridge Construction, 2023 Edition. Pages 350–359 of 1,006.