NOTE # 4
Compressive strength testing for all concrete mixes, excluding those containing fly ash (at 20 percent or greater pozzolan cement replacement), will be done at 28 days. Compressive strength te sting for concrete mixes containing fly ash, at 20 percent or greater pozzolan cement replacement, will be done at 56 days.
NOTE #5 Coarse aggregate for concrete shall meet the requirements of Se ction “AA” or, with Department approval, SP1 or SP2 (refer to Standard Specification Section 518, Structural Co ncrete Repair).
Each concrete mix design shall be submitted by the Contractor to the Department for approval. No concrete shall be placed on a project until the c oncrete mix design is approved by the Department. For the first time use of a concrete batch plant or a change i n pozzolan source or type, the Contractor shall conduct a trial batch at the concret e plant utilizing transit mixers. The Contractor shall submit four clearly identified 4-inch diam eter x 8-inch high cylinders to the Department, at least 15 days prior to the first placemen t, for permeability testing. Full documentation shall be submitted with the cylinders and must in clude actual batch weights and all concrete test properties. The cylinders shall be submi tted between the ages of 2 and 7 days. The mix design submitted by the Contractor shall include the f ollowing information:
A Description of individual coarse aggregate stockpiles, original source, bulk specific gravity, absorption, gradation, and alkali silica reactivity te st results. A combined coarse aggregate blended gradations hall be provided, including the pe rcentage of each coarse aggregate used. B Description of fine aggregat e, original source, bulk specific gravity, absorption, colorimetric, gradation, Fineness Modulus (F.M.), alkali-silica reactivity and sand equivalent test. C Description and original source and amount of cement and pozz olanic material.
D Target water cement ratio.
E Target water content by volume.
F Target strength.
G Target air content, slump and concrete temperature.
H Target concrete unit weight.
I Type, manufacturer, and dosages of air entraining and chemica l admixtures.
J Target KOhm-cm Value
Approval by the Department will be contingent upon the ability of the mix design proportions to meet concrete strength and permeability requirem ents and other factors that affect durability. Concrete mix designs shall contain no more than 30 percent fly ash or 50 percent slag pozzolan cement replacement, by weight. Cast-in-place concrete shall contain no more than 635 lbs./yd 3 of cement and not more than 660 lbs./yd3 of cementitious material. Pozzolans are included as cementiti ous material. ClassS concrete shall contain a minimum of 650 lbs./ yd 3 of cementitious material. All concrete mixes must be designed in accordance with the cri teria of this Section. The design proportions with the fine aggregates designated as a percent of the total aggregate must be stated in terms of aggregates in a saturated, surface dry condition and the batch weights will be adjusted by t he Contractor for the actual moisture of the aggregate at the time of use.
Self-consolidating concrete (S CC) may be used for Class A, LP or P mixes when approved by the Resident. SCC shall meet the requirements for s trength, entrained air and permeability for the respective concrete Class. SCC shall be te sted for slump flow in accordance with ASTM C1611; the visual stability index (VSI) sh all be 0 or 1. No change in the source, proportions or character of the mix in gredients may be made without notice to the Department and no new mix ingredients sha ll be used until the Department has approved such ingredients and new mix proportions, if they change. The Contractor shall notify the Resident of any changes to the coarse aggregate blend prior to supplying concrete to the project.
502.06Batching Measuring and batching of materials for Struc tural Concrete shall
be performed at an approved batching plant. The plant shall mee t the requirements of AASHTO M-157. Batching plants will be inspected annually for ap proval by either the Department or by the National Ready Mixed Concrete Association. The Contractor shall provide a Certificate of Compliance for e ach truckload of concrete to the Department at the time of the load placement. The Certificate of Compliance shall be a form acceptable to the Department and shall include: Contract Name and Number Bridge Name
Manufacturing Plant (Batching Facility) Name of Contractor (Contractor) Date Time Batched/Time Discharged Truck Number Quantity (Quantity Batched this Load) Type of Concrete by Class and Department Mix Design Number Cement Brand or Type, and Shipment Certification Number Temperature of Concrete at Discharge Target Weights per cubic yard and Actual Batched Weights for:
and water added at the project)
502.07Mixing and Delivery A. All transit mixers used in the production and delivery of Struc tural Concrete shall be
inspected annually by the Department. Delivery and discharge o f the concrete from the mixer shall be completed within a maximum of 90 minutes fro m the time the cement is added to the aggregate, except that in hot weather wh en the concrete mix temperature exceeds 70°F, or under other conditions contributin g to quick stiffening of the concrete, delivery and discharge from the mixer shall be completed within 60 minutes. When approved by the Resid ent, the use of a retarding admixture (Type D) may be used for increasing the 60 minutes discharge time to 90 minutes, provided concrete temperatures are kept below 80ºF and conditions contri buting to quick stiffening of the concrete are not present. With prior approva l of the Resident, an approved hydration stabilizing admixture may be used to increas e the discharge time.
from the job site and disposed of properly.
502.08Cold Weather Concrete Concrete shall not be placed aga inst frozen surfaces
All frost, ice, and snow shall be removed from all material th at will be in contact with fresh concrete. Unless authorized by the Resident, the mixing and placing of c oncrete shall be discontinued when the atmospheric temperature is below 40°F in the shade and dropping
and shall not be resumed until the atmospheric temperature is a s high as 35°F in the shade and rising. If authorization is granted for the mixing and pla cing of concrete under atmospheric conditions different from those specified above, th e water shall be heated to a temperature not exceeding 180°F. When either the aggregate or water is heated to above 120°F, they are to be combined fir st in the mixer before the ce ment is added. If the atmospheric temperature is below 25°F, the aggregate shall also be heated. Materials containing frost or lumps of frozen material shall not be used. Stockpiled aggregates may be heated using dry heat or steam. Aggregates shall not be heated directly by gas or oil flame or on sheet metal over a fire. When aggregates are heated in b ins, steam coil or water coil heating or other methods that will not be detrimental to the ag gregates may be used. The heating apparatus shall be capable of heating the mass uniforml y and preventing the occurrence of spots of overheated material. The minimum temper ature of the mixed concrete shall be in accordance with Table 2, when it is placed in the forms. Salt, other chlorides or other unapproved chemicals shall not be added to t he concrete for any reason whatsoever.
TABLE 2 COLD WEATHER TEMPERATURE TABLE
MINIMUM FORM DIMENSION SIZE Less than 12 inches 12 to 36 inches 36 to 72 inches Greater than 72 inches 60°F 55°F 45°F 40°F MINIMUM CONCRETE TEMPERATURE AS PLACED
When permitted by the Resident, footings may be protected by c ompletely submerging them by admitting water inside the cofferdam. Until submersion takes place, the temperature of the concrete and its surface shall be contro lled as specified above. Submersion shall proceed slowly and the temperature of the air or water shall be maintained sufficient to prevent ice from forming within the cofferdam for a period of 7 days after the placing of the concrete. When depositing concrete under water, there shall be no ice in side the cofferdam. Permission given to place concrete under the conditions mentio ned above and as described in the Contractor's QCP shall not relieve the Contrac tor of its responsibility for obtaining satisfactory results. The Contractor shall be wholly responsible for the protection of concrete during cold weather operations and any concrete inj ured by frost action or overheating shall be removed and replaced at the Contractor's e xpense.
502.09Forms and False work
securely braced, strutted and tied to prevent motion and distortion while concrete is being placed in them. The forms shall be strong enough to safely sup port the weight of the
concrete and all superimposed loads (such as runways, concrete buggy loads, workers, scaffolding, etc.) placed upon them.
Forms shall be built to conform to the dimensions, location, co ntours and details shown on the Plans. The faces of forms against which the concrete is to be placed shall be dressed smooth and uniform and shall be fr ee from winds, twists, buckles and other irregularities. Stay-in-place forms of any type will not be permitted for any p art of slab structures, unless otherwise indicated on the Plans. The placing of concrete in excavated pits and trenches without forms will not be permitted. All corners within the forms shall be fitted with chamfer strips mitered at their intersections, except that chamfer strips will not be required as follows: (1) on corners of slab blocking of interior steel beams and the inside of exterio r steel beams; (2) on corners constructed transversely at the underside of the slab of supers tructures which consist of a concrete slab on steel beams; (3) on footings not exposed to v iew; and (4) on all structures when more than 2 feet below the final finished grade line. Chamfer strips shall have a width across the diagonal face betw een ½ and ¾ inch. The size to be adopted for a given portion of the work shall depend upon the general dimensions. Except where special size chamfer strips are shown on the Plans , the size of chamfer strips shall be uniform on individual pr ojects. Provision shall be ma de for the chamfering of the top edges of abutment bridges eats and wing walls, tops of piers and retaining walls, tops of through girders, roadway curbs, etc., by nailing chamfer strips inside the forms. Unless otherwise provided, all chamfer strips shall produce plain flat surfaces on the concrete. The forms for beams, girders and spandrel arches shall be so co nstructed as to permit the sides to be removed without disturbing the supports. All foreign matter within the forms shall be removed before dep ositing concrete in them. In all cases where metal or composite anchorages or ties within or through the face forms are required to hold the forms in their correct position, such anchorages or ties shall be of ample strength and shall be so constructed that the metal /composite work can be removed to a depth of not less than 1 inch from the face and ba ck surfaces of the concrete without damaging such surfaces. Elevations will be taken on the top flanges of structural beams and girders for determining the depth of blocking necessary for the constructio n of the forms for the concrete slab, after the following conditions have been satisfied:
including any required flooring beams, stringers and intermedia te diaphragms,
unless an alternative plan is submitted by the Contractor and a pproved by the Department.
The Contractor shall submit working drawings for approval of th e proposed forms and false work supporting the overhanging portion of the superstruc ture slab in accordance with members, the proposed loads and the weight of concrete forms to be carried by the members. In the construction of forms a nd false work for the portion of superstructure slabs overhanging the exterior members of beam and girder spans, forms and supporting devices resulting in point loadings on the exterior members shall not b e used. Loads resulting from supporting devices shall be distri buted directly to the flanges by means of brackets or braces. All forms shall be inspected and approved by the Department bef ore the placing of any concrete within them.
with form oil or other approved surface treatment. Form surfaces shall be treated before placing the reinforcing steel.
superstructures shall be comprised of members having ample stru ctural sections to resist all loads imposed upon them, with deformations less than: (SpanLe ngth) / 360.
When the vertical members of false work consist of piles or whe n framed or other false work is supported upon piles, the piles shall be driven to secu re a safe load resistance. When false work is supported upon mud sills, the foundation pre ssures resulting from the imposed loads upon the mud sills (false work, forms, fresh concrete, scaffolding, etc.) shall not exceed the capacity of the on-site soils. All false work systems shall be designed to support all vertica l loading and any differential settlement forces, all horizontal and longitudinal forces, and shall account for any temporary unbalanced loading due to the placement sequence of the concrete. Sufficient redundancy shall be de signed into false work systems so that the failure of any member shall not cause a collapse. False work systems adjacent to and/or over traveled ways shall additionally be designed to resist any vibration for ces due to traffic and shall incorporate sufficient protection against impact by errant vehi cles.