Loading...
HomeMy WebLinkAbout024119-33 Selective Concrete Demolition for RepairSECTION 024119-33 - SELECTIVE CONCRETE DEMOLITION FOR REPAIR PART 1  GENERAL 1.1 RELATED DOCUMENTS A. Drawings and general provisions of contract, including general and supplementary conditions and Division 1 specification sections, apply to work of this section. 1.2 DESCRIPTION OF WORK A. This section includes: 1. Removing concrete. 2. Protecting persons and property. 1.3 DEFINITIONS A. Removal includes complete removal in designated areas and legal disposal of existing items except those noted to remain property of Owner. B. Delaminations are fracture planes (internal cracks) within concrete, typically parallel to face of a member. C. Spalls are potholes, cavities, or voids in floor slabs and beams, usually the result of a delamination migrating to face of a member. When this delamination reaches the surface, it breaks away, leaving a spall. D. Unsound concrete exhibits one or more of the following characteristics: 1. Incipient fractures present beneath delaminated or spalling surfaces. 2. Honeycombing. 3. Friable or punky. 4. Deterioration from freeze-thaw action. E. Defective reinforcing bars are those that have lost more than 15 percent (10 percent if two or more consecutive units are affected) of original cross-sectional area through corrosion. F. Damaged reinforcing bars are those that have lost more than 15 percent (10 percent if two or more consecutive units are affected) of original cross-sectional area as a direct result of Contractor's removal operations. Damaged material shall be replaced or reinforced at Contractor's expense. 1.4 JOB CONDITION AND COORDINATION WITH OWNER'S REPRESENTATIVE A. Coordinate demolition with Owner's Representative. B. Provide time schedule for demolition work that is part of total job sequencing. C. Provide dumpsters or truck for removing debris. D. Some work may have to be scheduled during hours of light use or when the area is closed. 1.5 PROTECTION OF EXISTING FACILITIES A. Contractor shall perform his operation in such a manner as to cause no damage to existing facilities. Provide temporary wood coverings of finished surfaces that may be damaged during removals. Damage resulting from removals shall be repaired by Contractor at no cost to Owner. 1.6 DUST, DEBRIS, AND NOISE CONTROL A. Before start of work, review with Owner's Representative requirements for dust, debris, and noise control. Control measures shall be in place before work commences. 1.7 DISPOSITION OF MATERIALS A. Items to be relocated under this contract shall be stockpiled in location as directed by Owner. B. Except relocated and reserved items, title to materials and equipment to be removed shall be vested to Contractor. Promptly remove material not reused in construction. Remove and legally dispose of debris. 1.8 BARRICADES AND SIGNS A. Provide necessary barricades and signs needed to direct personnel around work areas. B. Provide special exit signs when normal means of egress are temporarily blocked by construction activities. PART 2 - PRODUCTS See Section 030100. PART 3 - EXECUTION 3.1 JOB CONDITIONS A. Examine areas where demolition work shall occur. Do not proceed with demolition until conditions preventing scheduled work are corrected. 3.2 PREPARATION A. Notify Owner at least 24 hours before commencing work. B. Locate existing active utility lines in work area and determine requirements for disconnecting and capping. Coordinate continuation of services necessary for Owner's operations. 3.3 SURFACE PREPARATION FOR PATCHING A. Locate delaminations in members by sounding entire surface with hammer or chain. Mark limits of delaminated area with paint, chalk, or crayon. Designate area to be removed with straight lines in rectangular patterns for neat patch. B. Removals: 1. Saw cut perimeter of area to required depth without cutting into reinforcing steel and without overrunning cuts at corners. Make shallow cuts inside area to be removed. This second cutting shall facilitate removal of concrete. 2. Remove unsound concrete within marked areas using 15- to 30-pound chipping hammers equipped with gad point bits. 3. After required concrete has been removed, clean surface by sandblasting or high- pressure water to remove loose materials. 4. Where embedded reinforcement is exposed by concrete removal, exercise extra caution to avoid damaging it during removal of concrete. Remove concrete around reinforcement to provide minimum of ( inch clearance. If rust is on embedded reinforcement where it enters concrete, continue concrete removal until bare reinforcement is exposed or removals are terminated by Engineer. 5. Notify Engineer when removals have been completed so that they may be observed. Unsatisfactory cavity preparation shall be corrected as required by Engineer. 6. Clean rust from reinforcement by sandblasting. 7. Prior to placing patching materials, air blast cavities clean to remove sand and debris. END OF SECTION 024119-33 (3/09)