521.02 Pneumatically Applied Mortar
518 SECTION 521
521.01 Description
This work consists of providing and placing pneumatically applied mortar to: Construct portions of structures, Repair concrete structures, Texture concrete surfaces, Encase structural steel members, Line ditches and channels, and Pave slopes. This work includes preparing surfaces to receive mortar, and providing and placing reinforcing steel and anchors for reinforcement.
521.02 Materials
A.General Provide pneumatically applied mortar with a minimum of compression strength of 4,000 psi [27.6 MPa]. Provide materials in accordance with the following subsections: Material: Subsection: Fine Aggregate 701.05 Coarse Aggregate 701.06 Water 701.04 Portland Cement 701.02 Bar Steel Reinforcement – Billet Steel 723.01 Welded Steel Wire Fabric 723.02 Use no more than 30 percent coarse aggregate in combinations of fine and coarse aggregates. Provide coarse aggregate in accordance with Subsection 701.06, “Coarse Aggregate,” with gradation in accordance with AASHTO M 43, No. 8 or No. 89. The Department will allow the reuse of clean cement - covered fine aggregate (recovered rebound). Limit the use to no mo re than 20 percent of the total fine aggregate.
B.Anchor Studs If placing mortar against existing concrete or rock, provide anchor studs with at least ¼ in [6 mm] diameter expansion hook bolts placed in drilled holes to support reinforcing wire fabric or bars. Ensure individual bolts can resist a pullout force of 150 lbf [670 N]. Obtain the Engineer’s approval before using driven steel studs. Use driven steel studs with a diameter of at least ⅛ in [3 mm] and a length of at least 2 in [50 mm]. PNEUMATICALLY APPLIED MORTAR 521.04 519 521.03 EQUIPMENT For driven studs, provide equipment that uses an explosive as the driving force and can insert the stud or pin to a depth capable of sustaining the 150 lbf [670 N] pullout force without damaging the concrete.
521.04 Construction Methods
A.Proportioning Submit the mix design to the Engineer for approval before beginning the work. Unless otherwise required by the Contract, include a cement -to-aggregate ratio based on dry loose volumes. Ensure at least one -part cement to three and one -half p arts aggregate for concrete structures and steel members, and at least one -part cement to five parts aggregate for ditches, channels, and slopes. Use minimal water content to provide workability of the mix. Adjust the water content so the mix adheres and will not sag or fall from vertical surfaces, or separate in horizontal surfaces.
B.Mixing Use the dry or wet mix process. Use a paddle or drum -type mixer designed for pneumatic application to uniformly mix the materials before charging the placing equip ment. The Department will allow transit mix equipment and methods in the wet mix process.
C.Surface Preparation
1.Earth Grade the area as required by the Contract if placing pneumatically applied mortar against earth. Compact the area with moisture to provide a firm foundation and to prevent the mortar from losing moisture. Remove free surface water after compaction. Provide joints, side forms, headers, and shooting strips for backing or paneling if the Contract requires. Use ground or gauging wires t o establish thicknesses, surface planes, and finish lines.
2.Forms If placing mortar against forms, provide forms in accordance with Section 502, “Forms, Falsework, and Temporary Works.”
3.Concrete or Rock Chip -away deteriora ted and loose material with pneumatic or hand tools if placing mortar against concrete or rock. Cut square or slightly undercut shoulders 1 in [25 mm] deep along the perimeter of repair areas. Sandblast the surface to clean rust from exposed steel and to produce a clean, rough surface. Keep the surface wet for at least 1 hr. Allow the surface to dry just before applying the mortar.
D.Installation
1.Placement of Reinforcing Steel Install reinforcing steel in accordance with Section 511, “Reinforcing Steel for Structures.” Place reinforcing steel in new construction as required by the Contract. Secure reinforcing steel to
521.04 Pneumatically Applied Mortar
520 prevent displacement. For repair work, support reinforcing steel with anchor studs installed in the existing masonry, unless the Engineer approves the existing reinforcing steel. Space anchors no more than 12 in [300 mm] center -to-center on overhead surfaces, 18 in [450 mm] center -to-center on vertical surfaces, and 36 in [900 mm] center -to-center on top o f horizontal surfaces. Use at least three anchors in each patch area. Notify the Engineer before installing anchor studs. Place studs in locations that will prevent damage to the prestressing tendons or conduits embedded in the concrete. Reinforce repair work areas where the mortar thickness exceeds 1½ in [38 mm] with a single mat of either 2 in × 2 in [50 mm × 50 mm] of W1.2 × W1.2, or 3 in × 3 in [75 mm × 75 mm] of W1.4 × W1.4 welded wire fabric, unless otherwise required by the Contract. Reinforce whe re the mortar thickness exceeds 4 in [100 mm], for each 4 in [100 mm] layer of mortar thickness placed with a mat of wire fabric. Encase each mat of welded wire fabric in mortar and allow it to set before installing the next layer of mortar. Place fabri c no closer than ½ in [12 mm] to the prepared masonry surface. Place fabric parallel to and at least 1 in [25 mm] away from the finished surface. Pre -bend fabric to fit around corners and into re -entrant angles.
2.Placement of Mortar At the Engineer’ s request, submit employee credentials. Apply the mortar with pneumatic equipment that sprays the mix onto the surface at a velocity high enough to produce a compacted, homogeneous mass. Use an air compressor and delivery hose lines to provide a pressure of at least 35 psi [240 kPa] for 1 in [25 mm] nozzles. Maintain the velocity of the material as determined by job conditions to minimize rebound. Supply water to the nozzle at a uniform pressure of at least 15 psi [100 kPa] greater than the air pressure. Apply mortar with minimal water content to prevent cracking from shrinkage. Unless otherwise required by the Contract or approved by the Engineer, use shooting strips to make square corners, straight lines, and a plane surface of mortar. Place the strips to minimize rebound trapping. At the end of each workday or when stopping to place construction joints, taper the mortar to a thin edge. Before placing an adjacent section, clean and wet the construction joint in accordance with Subsection 521.04.C, “Surface Preparation.” Hold the nozzle from 2 ft to 4 ft [0.6 m to 1.2 m] away from the working surface. Direct the stream at right angles to the surface. Apply enough mortar layers to obtain the thickness shown on the Plans. Obtain the Engineer’s approval before applying mortar layers more than 1 in [25 mm] thick on vertical and overhead surfaces. Place layers without causing sag or decreasing the bond of the preceding coat. Allow sufficient time between successive layers in sloping, vertical, or overhanging work for the initial set to develop. While the initial set develops, clean the surface of laitance. Remove rebound and loose sand before placing new mortar layers to prevent them from embedding in the mortar. Apply materials within 45 min of mixing, unless otherwise approved by the Engineer. After curing and before the final acceptance, sound repaired areas. Replace unsound and cracked areas. PNEUMATICALLY APPLIED MORTAR 521.06 521 (a) Weather Limitations Apply pneumatically placed mortar on surfac es from 32 °F to 100 °F [0 °C to 35 °C], when the ambient temperature is not anticipated to drop below 35 °F [2 °C] within 24 hr after placement. Suspend mortar application during high winds or rain.
b.Protection of Adjacent Work Protect adjacent facilit ies from damage or discoloration by overspray, dust, or rebound. Immediately clean contacted areas by scraping, brushing, or washing.
3.Finishing Cut off high spots after completing mortar placement with a sharp trowel, or screed to a true plane determi ned by shooting strips, the original masonry surface, or as directed by the Engineer. If using cutting screeds, lightly apply the screed without disturbing the mortar, and work the screed in an upward direction on vertical surfaces. Unless otherwise requ ired by the Contract, give the finished mortar surface a final flash coat of ¼ in [6 mm] of mortar. Create a uniform appearance on exposed surfaces.
4.Curing and Protecting Cure pneumatically placed mortar in accordance with Subsection 509.04.F(3), “Water Method.” If the Engineer determines that the “Water Method” is not practical, cure pneumatically placed mortar in accordance with Subsection 509.04.F(4), “Liquid Membrane Curing Compound Method.” If using Subsection 509.04.F(3) , “Water Method, ” cure for at least 96 hr. Protect the mortar from freezing during the curing period in accordance with Subsection 509.04.B, “Protection of Concrete from Environmental Conditions.”
521.05 Method of Measuremen T — Vacant
521.06 Basis of Payment
The Department will pay for each pay item at the contract unit price per the specified pay unit as follows: Pay Item: Pay Unit: PNEUMATICALLY PLACED MORTAR Square Yard [Square Meter]
523.01 Concrete Surface Repair By Sealing
522 SECTION 523 CONCRETE SURFACE REPAIR BY SEALING
523.01 Description
A.General This work consists of sealing bridge decks and approach slabs and filling and rebonding cracks.
B.Definitions Acrylic Resins. Thermoplastics, thermosetting polymers, copolymers of acrylic acid, methacrylic acid, esters of these acids, or acrylonitrile, used to produce synthetic rubbers and lightwe ight plastics. Density. Mass per unit volume of a material. Bulk Cure. Time required for the methacrylate monomer to harden and form a polymer. Epoxy Penetrant. A low viscosity, two component, epoxy -resin bonding system for application to Portland -cement concrete. Flash Point. Lowest temperature at which a material gives off explosive or ignitable vapors. High Molecular Weight Methacrylate (HMWM). Non -fuming monomer with a low viscosity, low volatility, low initial shrinkage, and high flash point. Member of the acrylic family of monomers and polymers. Initiators. Chemicals that start polymerization. Monomers. Liquid molecules that a catalyst reaction converts into solid polymers. Promoters. Chemicals used with initiators to accelerate polymerization. Resin . Natural or synthetic, solid or semi -solid organic material of indefinite and often high molecular weight, with the tendency to flow under stress. Shelf Life. Maximum interval during which a material may be stored and remain in a usable and safe condition . Surface Cure. Amount of time required after placement before the HMWM treated concrete is without surface liquid or tackiness. Vapor Pressure. Component of atmospheric pressure caused by vapor; expressed in inches, centimeters, or millimeters of height o f a column of mercury. Measures the volatility and depletion rate of monomers. Viscosity. Resistance to flow by gases or liquids subjected to shear stress. Working Time. Elapsed time after mixing methacrylate monomer with catalyst before solution viscosit y increases. Depends on the temperature and the amount of initiators and promoters used. Varies with the manufacturer’s monomer system.
Source: Oklahoma Standard Specifications for Highway Construction, 2019 Edition. Pages 532–535 of 935.