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2. Deposit concrete continuously and rapidly enough so that the layer supporting the <br /> one being placed is still plastic. If impossible to place, locate construction joints <br /> where shown on drawings or as approved. Do not use partially hardened or <br /> contaminated concrete. <br /> 3. Remove temporary form spreaders when concrete reaches them. <br /> 4. Do not begin placing of concrete in supported elements until the concrete ' <br /> previously placed in element is no longer plastic. <br /> 5. Deposit concrete as nearly as practicable in its final position to avoid segregation <br /> due to rehandling or flowing. Do not subject concrete to any procedure which will <br /> cause segregation. <br /> C. Compacting: <br /> 1. Consolidate all concrete by vibration, spading, rodding, or forking so that the <br /> concrete is thoroughly worked around the reinforcement, around embedded , <br /> items, and into corners of forms, eliminating all air or stone pockets which may <br /> cause honey-combing, pitting, or planes of weakness. <br /> 2. Internal vibrators shall have a minimum frequency of 8,000 revolutions per minute <br /> and shall be operated by competent workmen. Over-vibrating and use of <br /> vibrators to transport concrete within forms shall not be allowed. Insert and <br /> withdraw vibrators at many points, from 18 to 30 inches apart, for 5 to 15 seconds <br /> duration. Keep a spare vibrator on the job site during all concrete placing ' <br /> operations. <br /> 3. Compact concrete in slabs thoroughly by means of screeds. <br /> D. Bonding: Where fresh concrete is to be placed against hardened concrete and bonded <br /> thereto, dampen (but do not saturate)the hardened concrete. If bonding is required in a <br /> critical section, obtain approval from Engineer of method proposed. <br /> 3.05 FORM REMOVAL <br /> A. Leave site development work formwork for and other parts not supporting the weight of <br /> the concrete, in place during the curing period for a minimum of 48 hours. <br /> 3.06 REPAIRING AND PATCHING ' <br /> A. Patch all tie holes and all repairable defective areas immediately after form removal. <br /> B. All honeycombed and other defective concrete shall be removed to sound concrete with ' <br /> edges perpendicular to the surface. Dampen the area to be patched and an area at least <br /> 6 inches wide surrounding it to prevent absorption of water from the patching mortar. Mix <br /> a grout of neat Portland cement and water and some fine sand passing a No. 30 mesh <br /> sieve, to the consistency of thick cream and brush it well into the surface. <br /> C. Make the patching mixture of the same material and approximately the same proportions <br /> as used for the concrete, except omit the course aggregate. The resultant mortar shall <br /> consist of not more than I part cement to 2-1/2 parts sand by damp loose volume. ' <br /> D. On exposed concrete, in order to produce a color matching that of the surrounding <br /> concrete, substitute white Portland cement(as determined by a trial patch)for a part of <br /> the gray Portland cement. <br /> E. Do not use more mixing water than necessary for handling and placing. Mix the patching ' <br /> mortar in advance and allow to stand with frequent manipulation with a trowel, without <br /> adding water, until it has reached the stiffest consistency that will permit placing. <br /> F. After surface water has evaporated from the area to be patched, brush the bond coat well , <br /> into the surface. When the bond coat begins to lose the water sheen, apply the premixed <br /> patching mortar. The mortar shall be thoroughly consolidated into place and struck off to <br /> leave the patch slightly higher than the surrounding surface. To permit initial shrinkage, <br /> leave it undisturbed for at least 1 hour before finishing it. Keep the patched area damp for <br /> 7 days. Do not use metal tools in finishing a patch in a formed wall which will be exposed. <br /> G. Tie Holes: Clean and thoroughly dampen, then fill with patching mortar. <br /> 3.07 FINISHES FOR FORMED SURFACES ' <br /> A. Smooth Form Finish: Patch tie holes and defects. Completely remove all fins. <br /> 3.08 SLABS ' <br /> A. Screeding: After concrete has been thoroughly consolidated, screed slabs to the desired <br /> elevations and contours by means of accurately placed edge forms and intermediate <br /> screed strips. ' <br /> SPORTSMAN'S WAREHOUSE 02626-4 <br />