1017PRESSURE MORTAR POINTING AND SURFACING

1017.1DESCRIPTION—This work is the pointing and the surfacing of areas of structures.

1017.2MATERIAL—

galvanized, welded straight-line fabric, conforming to one of the following:

• No. 12 gage wire, spread 2 inches in each direction;

• No. 10 gage wire, spaced 3 inches in each direction; or

• as indicated.

Certify as specified in Section 106.03(b)3.

Certify as specified in Section 106.03(b)3.

1017.3CONSTRUCTION—

and disintegrated particles, and material that might impair the bond between the surfaces to be covered and the mortar mixture. Remove unsound concrete and mortar as directed, and thoroughly clean surfaces.

6 inches for 3-inch mesh. Fasten fabric together with wire ties at intervals of not more than 18 inches.

conform to the outlines of the members and hold approximately 3/4 inch away from the surface of the members, or as directed. Place 1/4-inch diameter bars vertically on each side of the webs, then tie in place, using holes in the webs or clip plates. Space on 3-foot centers, or as indicated. Tie the fabric outside of and to the bars, on approximately 12-inch centers. Place the fabric or bars clear of the surface of the members.

otherwise indicated or directed, place a layer of fabric for each 3 -inch layer of mortar or fraction thereof. More than one layer of fabric may be attached to an anchor bolt, provided the bolt is long enough. Hold the fabric in place by means of lead -collared expansion bolts, either 1/4 inch by 3 inches, or 3/8 inch by 4 inches. Use longer bolts, where necessary. Space 1/4 -inch diameter bolts approximately 20 inches center-to-center in each direction, starting 3 inches from the outside edges of the areas to be pressure-mortared. Space 3/8-inch diameter bolts approximately 30 inches center-to-center in each direction,

starting 6 inches from the outside edges of the areas to be pressure mortared. Fasten the fabric to the expansion bolts away from the prepared surface, with 1 inch clear below the finished surface of the repair. Where existing reinforcement is exposed due to removal of deteriorated concrete, fabric may be tied to this reinforcement at 18-inch intervals, to form a cage to position and support the fabric within 1 inch of the finished surface of repair. Avoid excessive fabric layers, which may create planes of weakness or internal stresses.

mix the mortar in a batch mixer. Screen the dry-mix and remove material retained on a No. 4 sieve, before placing the mixture in the hopper of the mortar pressure gun. Do not mix more than 1 hour's supply of mortar at a time. Keep the mixture in the gun bin thoroughly stirred.

mixture. Increase the air pressure, as necessary, when the lift is greater than 25 feet, or when using more than 100 feet of hose. Maintain uniform air pressure. At the nozzle, maintain a uniform water pressure of at least 15 pounds per square inch greater than the air pressure at the gun. Supply pressure in the lower gun chamber to produce a nozzle velocity of 375 feet per second to 450 feet per sec ond, with a 1 1/4-inch tip opening. Vary these pressures and velocities only when directed. Determine the nozzle pressure and velocity from the nozzle velocity meter attached to the gun.

of approximately 3 1/2 gallons of water per bag of cement. Do not use a greater quantity of water than necessary to produce a proper mixture. When using reinforcement fabric, supply a moisture content of approximately 8%, for mortar below the fabric, and approximately 9% to 10% above the fabric.

pressure-gun foreperson, using only experienced personnel as gun and nozzle operators. When pointing masonry, saturate the surfaces with clean water before applying mortar. Whe n surfacing structural steel, keep the outer edges of the mortar at the flanges and stiffeners square and true to line by using shooting strips, placed to maintain the specified dimensions without trapping the rebound. Use guide strips at corners and other places, where necessary, to ensure true lines, corners, and the placement of specified thickness, dimensions, and designs. Bring mortared surfaces to a reasonably true plane, then finish the entire mortared area with a pressure-gun finish. Apply the main body of the mortar in at least two coats. Apply bottom surfaces in at least two coats to obtain proper adhesion and to avoid sagging. Bring the last main coat to within 1/8 inch of the proposed surface, then correct irregularities and remove high spots with trowels. Give the entire surface a thin coat of mortar, but do not trowel or float. If directed, give the final surfaces a finish using a long-bristled brush, saturated with clean water, then dragged over the surfaces. Do not work the surfaces with the brush. For masonry pointing, or pointing and surfacing, fill voids with mortar, making the surface flush with the adjacent face of the structure. After completing the pointing, clean the face of the masonry. Shoot mortar at right angles to the surface, holding the gun nozzle approximately 3 feet from the surface, when using a 3/4-inch or a 1-inch nozzle, or 4 feet from the surface, when using a 1 1/4-inch nozzle. Use a shorter distance only where working space requires closer shooting. Remove deposits of loose fine aggregate. If any deposit of loose, fine aggregate is covered by succeeding layers of mortar, remove the surfacing and replace with suitable mortar. At the end of a day's work or at other required stopping periods, slope off the mortar to a thin edge. Do not use square joints. Before shooting the adjacent section, joining new work to old work, or placing additional coats, clean this sloped portion, old work, or previous coat. Saturate the previous coat by a combination of air and water blasting. Do not place mortar unless the air temperature or the surface on which it is placed is 50F or higher.

96 hours. Protect pressure mortar pointing and surfacing on masonry surfaces, and where practical on structural steel, with burlap. Keep burlap wet during this curing period. If allowed as an alternative to burlap curing, apply Liquid Membrane Forming Curing Compound, Clear, as specified in Section 1001.3(p)3.a. Cure in cool and cold weather, as specified in Section 1001.3(p).

embankment material in layers no more than 4 inches in depth. Thoroughly compact mechanically, as specified in Section 202.3(f).

1017.4MEASUREMENT AND PAYMENT—