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DocuSign Envelope ID: B94F2D40-3B3C-47A7-86C2-6F1 B4F92C62C <br /> SECTION 04 01 20-MASONRY RESTORATION <br /> L. Immediately remove and dry clean all misplaced and excess mortar and residue from faces of units using stiff bristle <br /> brush. <br /> M. If shrinkage cracking develops within the newly installed mortar due to rapid drying, installed mortar should be lightly <br /> tempered with a fine spray of water by means of a garden sprayer. <br /> 3.6 SEALING CMU CRACKS <br /> A. Rout cracks in CMU block to a uniform depth of 3/4" minimum. <br /> B. For installation of backing material and sealant, see Section 07 92 00, Elastomeric Joint Sealants. <br /> C. Do not allow sealant to migrate onto faces of units. Tool the sealant to be flush with the face of units. <br /> 3.7 MORTAR REPAIRS <br /> A. Surface preparation. <br /> 1. Carefully follow the manufacturer's application instructions. Clean substrate of all loosely adhering matter or <br /> surface contaminants(oils,form-release agents, dust, old asphalt, etc.). Surfaces shall be sound and in spalled <br /> areas cleared of any loose or weak concrete. <br /> 2. Wire brush steel rebar to a white metal finish. Apply anti-corrosion agent according to the manufacturer's <br /> application instructions. <br /> 3. Immediately before the application of mortar thoroughly dampen repair area removing any excess standing <br /> water.After the surface has been prepared and predampened a"bond coat"of mortar is used to prime all repair <br /> areas. <br /> 4. To prepare the bond coat mixture, mix the product as described in Article 2.6 JOB MIXING and add an additional <br /> 1 pint of water per bag. Broom this bond coat on the prepared and predampened concrete.Apply mortar before <br /> the bond coat has dried. <br /> B. Installation and finishing. <br /> 1. Immediately after mixing, place and spread the mortar material by hand troweling. On large areas, use screed <br /> strips with vibratory screeding to level. Finish the topping with a float or broom or to the desired texture. <br /> a. A broom finish is required if an elastomeric coating is to be applied over the topping. <br /> b. For a hard,flat troweled surface,wait until the material is near final set, approximately 3 hours. <br /> 2. Do not add additional water to the surface during the finishing operation.Clean tools with water immediately after <br /> use. <br /> 3. Keep weep holes and area above flashing free of mortar droppings. <br /> C. Curing. <br /> 1. Mortar is self curing and no curing compounds are required. Do not use solvent based curing compounds. <br /> 2. When high winds, direct sunlight or temperatures exceeding 75 F exist, rewet the area and cover with <br /> polyethylene sheeting for 72 hours. <br /> 3. Do not wet cure such as by repeated rewetting or burlap or paper. Keep freshly repaired areas from freezing <br /> during curing period. <br /> 3.8 MASONRY UNIT REPLACEMENT <br /> A. Any masonry unit that has openings as a result of the removal of any exterior pipes, conduits, louvers or vents <br /> penetrating the CMU that are not functioning shall be removed and replaced and set in a new bed of mortar. <br /> B. New masonry units installed shall match present masonry in color, texture and compressive strength as closely as <br /> possible. <br /> 3.9 MASONRY UNIT CLEANING <br /> A. General: Carefully follow recommendations of the Brick Institute of America for cleaning brick or block surfaces. <br /> Protect other wall components from damage or staining during cleaning. Protect landscape elements from damage. <br /> Do not proceed with work until outside temperatures are 50 F and rising. Carefully mix cleaning chemicals in the <br /> proper concentration prior to application.No wet cleaning shall take place within seven days of tuck pointing or placing <br /> masonry. Water-only pressure cleaning of surfaces using low pressure, 100 - 300 psi maximum, at nozzle. Provide <br /> non-metallic bristle brushes and non-ionic detergent solution for removal of difficult stains and plant growth. Use no <br /> abrasive aggregates or steam. <br /> B. Select a minimum 20 square foot test cleaning area in an unobtrusive location at the rear of the building and conduct <br /> a sample cleaning of the masonry surface. Wait a minimum of 24 hours and inspect the masonry unit's condition. If <br /> judged satisfactory by the Engineer, proceed with cleaning. If unsatisfactory, retest until Engineer's approval is <br /> secured. <br /> 1. Clean with plain water,detergents, emulsifying agents or suitable proprietary compounds. <br /> C. Cleaning procedure: <br /> ©BOOMERANG DESIGN 0401 20-5 510 Meadowlands Drive,Hillsborough,NC <br /> BD#1835 ORANGE COUNTY, NC 12/07/2018 <br />