247 If any random or uncontrolled crack occurs outside three ( 3) inches from a doweled joint, the entire pavement within the lane where such crack occurs shall be removed for the entire fifteen ( 15) foot panel between joints. The dowel assembly or bars, as the case may be, shall be replaced with a new dowel as sembly with drilling. The new joint over the dowel assembly shall be initially formed by the use of a removable insert or by sawing. The tie bars shall be replaced with a Modified Type E joint. The above described work shall be done at no additional cos t to the Division.
501.11 8-Transverse Joints in Concrete Shoulders: Dowel bars are not required in
paved shoulders except where turning traffic may use the shoulders as a lane.
501.12 Final Strike -Off, Consolidation and Finishing :
501.12.1 Sequence: The sequence of operations shall be strike -off and consolidation,
floating and removal of laitance, straight -edging, and final surface finish. Any addition of water to the surface of the concrete to assist in the finishing operations will not be permitted. When conditions are such that unusually rapid drying is occurring, an atomized mist may be used to prevent the rapid evaporation of water from the concret e surface during the final finishing.
501.12.2 Finishing at Joints: The concrete adjacent to joints shall be consolidated or
firmly placed without voids or segregation against the joint material, under and around all load transfer devices, joint assemblies, and other features designed to extend into the pavement. Concre te adjacent to the joints shall be mechanically vibrated as required in 501.9. The operation of the finishing machine over the joints shall not cause segregation of concrete and damage to or misalignment of joints.
501.12.3 Machine Finishing: The concrete shall be distributed as soon as placed. It shall
immediately be struck off and screeded by the finishing machine. Vibrators for full width vibration of concrete paving slab shall meet the requirements of 501.5.5. If uniform and satisfactory density of the concrete is not obtained by the vibratory method at joints, along forms, at structures, and throughout the pavement, the Contractor will be required to furnish equipment and methods which will produce pavement conforming to the Specifications.
501.12.4 Hand Finishing and Consolidation: Hand finishing will not be permitted
except under the following conditions: In the event of breakdown of the mechanical equipment, hand methods may be used to finish the concrete already dep osited on the grade. Areas of narrow widths or irregular dimensions, where operation of mechanical equipment is impractical, may be finished by hand. Concrete, as soon as placed, shall be struck off and screeded. A portable screed shall be used. If reinforcement is used, a second screed shall be provided for striking off the bottom layer of concrete. The surface screed shall be at least two ( 2) feet longer than the maximum width of slab to be struck off. It shall be sufficiently rigid to retain it s shape under all working conditions, and constructed either of metal or of other suitable material shod with metal. Consolidation shall be attained by the use of suitable vibrator or other equipment. 248 In operation the screed shall be moved forward on t he forms in the direction the work is progressing, using a combined longitudinal and transverse shearing motion, so manipulated that neither end is raised from the side forms during the striking process. This shall be repeated until the surface is of unif orm texture, true to grade and cross section, and free from porous areas.
501.12.5 Floating: After the concrete has been struck off and consolidated, it shall be
further smoothed, trued, and consolidated by means of a mechanical longitudinal float, exc ept when waived by the Engineer. If necessary, following one of the methods of floating described, long -handled floats may be used to smooth and fill in open textured areas in the pavement. Care shall be taken not to work the crown out of the pavement du ring the operation.
501.12.5 1-Mechanical Method: The mechanical longitudinal float shall be
maintained in proper working order. At the beginning of each day's operation the float shall be checked and adjusted to the design crown of the pavement. A sm all amount of mortar shall be carried ahead of the float at all times. The forward speed shall be adjusted so that succeeding strokes of the float shall overlap on each transverse trip. The float shall pass over each area of pavement sufficient number of times until the surface shows no variation from straightedge requirements, but excessive operation over a given area will not be permitted. All excess water, laitance, or other foreign material shall be wasted over the side forms on each pass. Pipe float devices may be used for longitudinal floating when slipform paving.
501.12.5 2-Alternative Mechanical Method: As an alternate to the above method,
the Contractor may use a machine composed of a cutting and smoothing float, or floats, suspended fro m and guided by a rigid frame. The frame shall be carried by at least four visible wheels riding on, and constantly in contact with, the side forms.
501.12.5 3-Hand Method: The hand -operated longitudinal float shall be not less than
twelve ( 12) feet in length and six ( 6) inches in width, properly stiffened to prevent flexibility and warping. The float shall be operated from foot bridges resting on the side forms and spanning but not touching the concrete. The float shall be worked with a sawing motion , while held in a floating position parallel to the road centerline and passing gradually from one side of the pavement to the other. Movement ahead along the centerline of the pavement shall be in successive advances of not more than one -half the length of the float. Any excess water, laitance, and other foreign material shall be wasted over the side forms on each pass.
501.12.6 Straightedge Checking and Surface Correction: After the floating has been
completed and the excess water removed, but while the concrete is still plastic, the surface of the concrete shall be tested for trueness with a ten (10) foot straightedge. The Contractor shall furnish and use a ten (10) foot straightedge swung from handles at least three ( 3) foot longer than one -half the width of the slab. The straightedge shall be held in contact with the surface in successive positions parallel to the road centerline and the whole area gone over from one side of the slab to the other as necessary. Advance along the road shall be in successive stages of not more than one -half the length of the straightedge. Any depressions found shall be immediately filled with freshly mixed concrete, struck off, consolida ted, and refinished. High