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inches for dimensioned masonry and 2 inches in 12 inches for all other classes.

(d) Joint surfaces.—In all classes of masonry except dimensioned masonry, the joint surfaces of face stones shall form an angle with the bed surfaces of not less than 45 degrees.

In dimensioned masonry, the joint surfaces shall be normal to the bed surfaces. They shall also be normal to the exposed faces of the stone for at least 2 inches, from which point they may depart from normal not to exceed 1 inch in 12 inches.

The corners at the meeting of the bed and joint lines shall not be rounded in excess of the following radii: (1) Cement rubble masonry

142 inches. (2) Class B masonry

1 inch. (3) Class A masonry

No rounding. (4) Dimensioned masonry

No rounding. (e) Arch ring stone joint surfaces.-Arch ring stone joint surfaces shall be radial and at right angles to the front faces of the stones. They shall be dressed for a distance of at least 3 inches from the front faces and the soffits, from which points they may depart from a plane normal to the face not to exceed 34 inch to 12 inches. The back surface in contact with the concrete of the arch barrel shall be parallel to the front face and shall be dressed for a distance of 6 inches from the intrados. The top shall be cut perpendicular to the front face and shall be dressed for a distance of at least 3 inches from the front.

When concrete is to be placed after the masonry has been constructed, adjacent ring stones shall vary at least 6 inches in depth.

(f) Stratification.—Stratification in arch ring stones shall be parallel to the radial joints and in other stones shall be parallel to the beds.

(g) Finish for exposed faces.—Face stones shall be pitched to line along all beds and joints. The kind of finish for exposed faces shall be as shown on the plans or the special provisions. The following symbols will be used and they shall be understood to represent the type of surface or dressing specified below:

Fine pointed (F. P.).—In which the point depressions shall be approximately 48 inch apart with surface variation not to exceed 48 inch from the pitch line.

Medium pointed (M. P.).—In which the point depressions shall be approximaely 5/8 inch apart with surface variations not to exceed 14 inch from the pitch line.

Coarse pointed (C. P.).-In which the point depressions shall be approximately 1 to 144 inches apart with surface variations not to exceed 3 inch from the pitch line.

Split or seam face (S.).—In which the surface shall present a smooth appearance, be free from tool marks, with no depressions below the pitch line and no projection exceeding 34 inch beyond the pitch line.

Rock faced (R. F.).-In which the face shall be an irregular projecting surface without indications of tool marks, with no concave surfaces below the pitch line, and with projections beyond the pitch line, when measured in inches, not exceeding the figure preceding the symbol as used on the plans or in the special provisions, e.g., “142 R. F.” means projections beyond the pitch line not exceeding 142 inches. Where a "variable rock face" is specified, stones of the same height of projection shall be well distributed.

Removal of drill and quarry marks from the faces of stones in cement rubble masonry will not be required.

610.04 Quarry Operations. Quarry operations and delivery of stone to the point of use shall be organized so as to insure keeping deliveries well ahead of masonry operations. A sufficiently large stock of stone of the kinds being used in the work shall be kept on the site at all times, to permit adequate selection of stone by the masons.

610.05 Mortar. Mortar shall conform to the requirements of subsection 705.05.

Construction Requirements 610.06 General. All construction other than stone masonry shall conform to the requirements prescribed in other sections for the several items of work entering into the completed structure.

610.07 Excavation and Backfill. Excavation and backfill shall conform to the requirements of Section 206 modified as follows:

For filled spandrel arches the filling shall be carefully placed in such manner as 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.

610.08 Falsework. Arch centering shall be constructed in accordance with construction drawings submitted by the Contractor as required by subsection 105.02. Suitable wedges shall be provided for raising or lowering the forms to exact elevation and for taking up any settlement occurring during loading. Centering shall be lowered gradually and symmetrically so as to avoid overstresses in the arch.

When directed, centering shall rest upon approved jacks in order to take up and correct any slight settlement which may occur after the placing of masonry has begun. In general, centering shall be struck and the arch made self-supporting before the railing or coping is placed. For filled spandrel arches such portions of the spandrel walls shall be left for construction subsequent to the striking of centers as may be necessary to avoid jamming of the expansion joints.

When, in the opinion of the Engineer, additional falsework and bracing are necessary to hold the stones in proper position, the Contractor shall construct such falsework and bracing in a manner satisfactory to the Engineer, but failure of the Engineer to order their construction will not release the Contractor from his obligation to build a satisfactory structure.

610.09 Sample Section. If required by the special provisions, the Contractor shall build, at a site designated by the Engineer, an L-shaped sample section of wall not less than 5 feet high and 8 feet long, showing examples of face wall, top wall, method of turning corners, and method of forming joints, which shall be subject to the Engineer's approval. No masonry other than the foundation masonry shall be laid prior to the approval of such samples.

610.10. Arch Ring Templet. If required by the special provisions, a full-size template of the arch ring shall be laid out near the quarry site, showing face dimensions of each ring stone and thickness of joints. The nplate shall be approved by the Engineer before the shaping of any ring stone is started, and no ring stone shall be placed in the structure until all ring stones have been shaped, dressed, and approved by the Engineer.

610.11 Selection and Placing. When the masonry is to be placed on a prepared foundation bed, the bed shall be firm and normal to, or in steps normal to, the face of the wall, and shall have been approved by the Engineer before any stone is placed. When it is to be placed on foundation masonry, the bearing surface of this masonry shall be cleaned thoroughly and wetted immediately before the mortar bed is spread.

All masonry shall be constructed by exprienced workmen. Face stones shall be set in random bond so as to produce the effect shown on the plans and to correspond with the sample section approved by the Engineer.

Care shall be taken to prevent the bunching of small stones or stones of the same size. When weathered or colored stones, or stones of varying texture, are being used, care

shall be exercised to distribute the various kinds of stones uniformly throughout the exposed faces of the work. Large stones shall be used for the bottom courses and large, selected stones shall be used in the corners. In general, the stones shall decrease in size from the bottom to the top of work.

All stones shall be cleaned thoroughly and wetted immediately before ing and the bed which is to receive them shall be clean and moistened before the mortar is spread. They shall be laid with their longest faces horizontal in full beds of mortar, and the joints shall be flushed with mortar.

The exposed faces of individual stones shall be parallel to the faces of the walls in which the stones are set.

The stones shall be so handled as not to jar or displace the stones already set. Suitable equipment shall be provided for setting stones larger than those that can be handled by two men. The rolling or turning of stones on the walls will not be permitted. If a stone is loosened after the mortar has taken initial set, it shall be removed, the mortar cleaned off, and the stone relaid with fresh mortar.

Arch ring stone shall be carefully set to exact position and held in place with hardwood wedges until the joints are packed with mortar.

610.12 Beds and Joints. The thickness of beds and joints for face stones shall be as follows:

Beds in inches Joints in inches Cement rubble masonry

12 to 242 - 42 to 242. Class B masonry

12 to 2 42 to 2. Class A masonry

12 to 2 42 to 142. Dimensioned masonry

(See note) 84 to 1. NOTE: The thickness of beds in dimensioned masonry may vary from 94 inch to 1 inch from the bottom to the top of the work, but in each course the beds shall be of uniform thickness throughout. Unless shown otherwise on the plans, beds shall not extend in an unbroken line through more than 5 stones, and joints through more than 2 stones.

Joints in dimensioned masonry shall be vertical. In all other masonry, joints may be at angles with the vertical from 0 to 45 degrees.

Each face stone shall bond with all contiguous face stones at least 6 inches longitudinally and 2 inches vertically.

At no place shall corners of four stones be adjacent to each other.

Cross beds for vertical walls shall be level and for battered walls may vary from level to normal to the batter line of the face of the wall. All arch ring joints shall be completely filled with mortar.

610.13 Headers. When headers are required they shall be distributed uniformly throughout the walls of structures so as to form at least one-fifth of the faces.

610.14 Backing. The backing shall be built chiefly of large stones and in a workmanlike manner. The individual stones composing the backing and hearting shall be well bonded with the stones in the face wall and with each other. All openings and interstices in the backing shall be filled completely with mortar or with spalls surrounded completely by mortar.

610.15 Coping. Copings, if called for, shall be as shown on the plans. Where copings are not called for, the top of the wall shall be finished with stones wide enough to cover the top of the wall, from 142 to 5 feet in length, and of random heights, with a minimum height of 6 inches. Stones shall be laid in such a manner that the top course is an integral part of the wall. The tops of the top courses of stone shall be pitched to line in both vertical and horizontal planes.

610.16 Parapet Walls. Selected stones, squared and pitched to line and with heads dressed, shall be used in ends of parapet walls and in all exposed angles and corners. Headers shall be well interlocked and as many as possible shall extend entirely through the wall. Both the headers and stretchers in the two faces of the wall shall be well interlocked in the heart and shall comprise practically the whole volume of the wall. All interstices in the wall shall be completely filled with cement grout or with spalls completely surrounded with mortar or grout.

610.17 Facing for Concrete. Unless otherwise specified, the stone masonry shall be constructed before placing concrete. When provided for in the special provisions or upon the approval of the Engineer, the concrete may be placed before constructing the stone masonry.

(a) Stone masonry constructed prior to placing concrete.Hooked steel anchors consisting of No. 4 bars each bent into an elongated letter S shall be spaced 2 feet apart both horizontally and vertically unless closer spacing is shown on the plans or ordered in writing by the Engineer. To improve the bond between the stone masonry and the concrete backing, the back of the former shall be made as uneven as the stones will permit. Each anchor shall be rigidly embedded in a horizontal joint of the masonry with one end 2 inches from the faces of the stones. The other end shall project approximately 10 inches into the concrete backing.

When the stone facing has been laid and the mortar has attained sufficient strength, all surfaces against which concrete is to be placed shall be cleaned carefully and all dirt, loose material, and accumulations of mortar droppings removed.

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