Railings and copings shall not be constructed until centering has been struck and the arch made self-supporting.

For closed-spandrel arches, such portions of the spandrel walls as may be necessary to avoid jamming of the expansion joints, shall be left for construction subsequent to the striking of centers.

For filled-spandrel arches the filling shall be placed as provided in section 206, care being taken to load the ring uniformly and symmetrically. The filling material shall be acceptable to the Engineer and shall be placed in horizontal layers, carefully tamped, and brought up simultaneously from both haunches. Wedge-shaped sections of filling material against spandrels, wings, or abutments will not be permitted.

Concrete in arch rings and ribs shall be placed in the order shown on the plans. Generally, keys shall be placed at laps in reinforcing steel.

When permitted by the Engineer, arch rings may be cast in a single continuous operation.

(h) Concrete subfloor or wearing surface.—Concrete subfloor or wearing surface shall be as called for on the plans.

On steel truss spans, the concrete shall be placed symmetrically about the centerline of the span, beginning at the center and working simultaneously toward each end or beginning at the ends and working simultaneously toward the

center.

(i) Concrete railings and parapets.—Concrete railings and parapets shall not be placed until the centering or falsework for the span has been released, unless authorized by the Engineer. Special care shall be exercised to obtain smooth and tight-fitting forms which can be held rigidly to line and grade and can be removed without injury to the concrete. All moldings, panel work, and bevel strips shall be constructed according to the detail plans, with neatly mitered joints. All corners in the finished work shall be true, sharp, and clean-cut and shall be free from cracks, spalls, or other defects.

Precast railing members shall be cast in mortar-tight forms. The precast members shall be removed from the molds as soon as the concrete is sufficiently hard and shall then be kept covered with burlap saturated with water, or with a tarpaulin, for at least 3 days. After this treatment the curing shall be completed by immersion in water or by spraying not less than twice a day for a period of not less than 7 days.

The method of storage and handling shall be such as to preserve the edges and corners true and even. Any precast members that become chipped, marred, or cracked before

or during the process of placing shall be rejected and removed from the work.

In the construction of cast-in-place railing caps and copings built in connection with precast balusters, the balusters shall be protected from staining and disfigurement during the process of placing and finishing the concrete.

(j) Construction joints.-Construction joints shall be located where shown on the plans or permitted by the Engineer. Construction joints shall be perpendicular to the principal lines of stress and in general shall be located at points of minimum shear.

At horizontal construction joints, gage strips 11⁄2 inches thick shall be placed inside the forms along all exposed faces to give the joints straight lines. Before placing fresh concrete, the surfaces of construction joints shall be sandblasted or washed and scrubbed with a wire broom, drenched with water until saturated, and kept saturated until the new concrete is placed. Immediately prior to placing new concrete the forms shall be drawn tight against the concrete already in place and the old surface shall be coated thoroughly with a very thin coating of neat cement mortar. Concrete in substructures shall be placed in such manner that all horizontal construction joints will be truly horizontal and, if possible, in locations such that they will not be exposed to view in the finished structure. Where vertical construction joints are necessary, reinforcing bars shall extend across the joint in such a manner as to make the structure monolithic. Special care shall be taken to avoid construction joints through paneled wing walls or other large surfaces which are to be treated architecturally.

Necessary dowels, load-transfer devices, and bonding devices shall be placed as shown on the plans or directed by the Engineer.

(k) Expansion joints.-Expansion joints shall be located and formed as required on the plans.

(1) Open joints.-Open joints shall be constructed where shown on the plans by insertion and subsequent removal of a wooden strip, metal plate, or other approved material. The insertion and removal of the template shall be accomplished without chipping or breaking the corners of the concrete. Reinforcement shall not extend across an open joint unless so specified on the plans.

(2) Filled joints.-Poured expansion joints shall be constructed similar to open joints.

When premolded expansion joints are specified, the thickness of filler as installed shall be as required on the plans. The joint filler shall be cut to the same shape and size as that of the surfaces being jointed. It shall be fixed firmly

against the surface of the concrete already in place in such manner that it will not be displaced when concrete is deposited against it. Where necessary to use more than one piece of filler to cover any surface, the abutting pieces shall be placed in close contact and the joint between them shall be covered with a layer of asphalt-saturated roofing felt of not less than 40-pound grade, one side of which shall be covered with hot asphalt to insure proper retention. Immediately after the forms are removed, the expansion joints shall be inspected carefully. Any concrete or mortar that has sealed across the joint shall be cut neatly and removed. When, during construction, an opening of one-eighth inch or more appears in any joint over which any traffic will occur, the opening shall be completely filled with hot tar or asphalt as directed by the Engineer.

Necessary dowels, load-transfer devices, and other devices shall be placed as shown on the plans or directed by the Engineer.

(3) Steel joints.-The plates, angles, or other structural shapes shall be accurately shaped at the shop to conform to the section of the concrete floor. The fabrication and painting shall conform to the requirements of the specifications covering those items. When called for on the plans or in the special provisions the material shall be galvanized in lieu of painting. Care shall be taken to insure that the surface in the finished plane is true and free of warping. Positive methods shall be employed in placing the joints to keep them in correct position during the placing of the concrete. The opening at expansion joints shall be that designated on the plans at normal temperature, and care shall be taken to avoid impairment of the clearance in any manner.

(4) Water stops.-Water stops shall be placed in accordance with the requirements of section 616.

(1) Anchor bolts.-All necessary anchor bolts in piers, abutments, or pedestals shall be accurately set either in the concrete as it is being placed or in holes formed while the concrete is being placed or in holes drilled after the concrete has set. If set in the concrete as it is being placed, a bolt shall be placed in a section of standard black pipe, at least 2 inches larger in diameter than the bolt, and shall be anchored by passing it through a heavy steel washer at the bottom of the pipe. Holes may be formed by inserting in the fresh concrete oiled wooden plugs, metal pipe sleeves, or other approved devices, and withdrawing them after the concrete has partially set. Holes so formed shall be at least 4 inches in diameter. If drilled, holes shall be at least 1 inch larger in diameter than the bolts used. During freezing conditions, anchor bolt holes shall be protected from water

accumulations at all times. Bolts shall be set accurately and fixed with grout completely filling the holes. The grout shall consist of one part portland cement to one part finegrained sand.

Anchor bolts used in connection with expansion shoes, rollers, and rockers shall be located with due regard to the temperature at the time of erection. The nuts on anchor bolts at the expansion end of the span shall be adjusted to permit free movement of the span.

(m) Shoes and bearing plates.-Bridge seat bearing areas shall preferably be finished high and rubbed to grade. Shoes and bearing plates shall be set as provided in section 611.

(n) Drainage holes and weep holes.-Drainage holes and weep holes shall be constructed in the manner and at the locations indicated on the plans or required by the Engineer. Ports or vents for equalizing hydrostatic pressure shall be placed below low water.

Forms for weep holes through concrete may be clay pipe, concrete drain pipe, wooden boxes, or metal. If wooden forms are used, they shall be removed after the concrete is placed. Exposed surfaces of metal drains shall be painted or unpainted as indicated on the plans.

(0) Pipes, conduits, and ducts.-Pipes, conduits, and ducts that are to be encased in concrete shall be installed by the Contractor before the concrete is placed. Unless otherwise indicated, pipes embedded in concrete shall be standard, lightweight non-corrosive pipes. Pipes shall be held or braced rigidly during concrete placement in order to prevent their displacement.

(p) Piers and abutments.-No superstructure load shall be placed upon finished bents, piers, or abutments until the Engineer so directs, but the minimum time allowed for the hardening of concrete in the substructure before any load of the superstructure is placed thereon shall be 7 days when normal portland cement is used and 2 days when high-earlystrength cement is used.

(q) Removal of forms and falsework.-Unless concrete strength test specimens are designated in the special provisions as controls for form stripping and structure loading, the requirements herein shall apply.

Forms and falsework shall not be removed without the consent of the Engineer. The Engineer's consent shall not relieve the Contractor of responsibility for the safety of the work. Blocks and bracing shall be removed at the time the forms are removed and in no case shall any portion of the wood forms be left in the concrete.

Falsework removal for continuous or cantilevered structures shall be as directed by the Engineer or shall be such

that the structure is gradually subjected to its working stress.

To facilitate finishing, forms used on ornamental work, railings, parapets, and exposed vertical surfaces shall be removed in not less than 12 nor more than 48 hours, depending upon weather conditions. In order to determine the condition of concrete in columns, forms shall always be removed from them before the removal of shoring from beneath beams and girders.

In warm weather, falsework and forms shall remain in place under slabs, beams, girders, and arches for 14 days after the day of last pour, except that forms for slabs having clear spans less than 10 feet may be removed after 7 days and when high-early-strength cement is used, forms for all structures may be removed after 4 days.

In cold weather, the length of time that forms and falsework are to remain in place shall be as directed by the Engineer.

Falsework and centering for spandrel-filled arches shall not be struck until fills back of abutments have been placed up to the spring line. Falsework supporting the deck of rigid frame structures shall not be removed until fills have been placed back of the vertical legs.

601.12. Finishing Concrete Surfaces. Unless otherwise authorized, the surface of the concrete shall be finished immediately after form removal.

All concrete surfaces shall be given a class 1 finish. If further finishing is required, exposed surfaces shall be given a class 2 finish. Other finish classes may be specified on the plans for designated surfaces.

(a) Class 1, ordinary surface finish.—As soon as the forms are removed, all projecting wire or metal devices that have been used for holding the forms in place, and which pass through the body of the concrete, shall be removed or cut back at least one inch beneath the surface of the concrete. Lips of mortar and all irregularities caused by form joints shall be removed.

or

All small holes, depressions, and voids that show upon the removal of forms shall be filled with cement mortar mixed in the same proportions as that used in the body of the work. In patching larger holes and honeycombs, all coarse broken materials shall be chipped away until a dense uniform surface of concrete exposing solid coarse aggregate is obtained. Feathered edges shall be cut away to form faces perpendicular to the surface. All surfaces of the cavity shall be saturated thoroughly with water, after which a thin layer of neat cement mortar shall be applied. The cavity shall then be filled with stiff mortar composed of one part of portland