Reso 2007-1150 - Laserfiche WebLink

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hours. The structure shall be considered satisfactory if deflection "D" in feet, at end of 24 -hour period does not exceed value: D equals 0.001 (L x L) /t in which "L" is span in feet, "t" is depth of slab or beam in inches. D. If deflection exceeds "D" in the above formula, the concrete shall be considered faulty unless within 24 hours after removal of the load, slab or beam under test recovers at least 75% of observed deflection. E. Should the strength of test cylinders fall below 60% of the required minimum 28 day strength, the concrete shall be rejected and shall be removed and replaced. 3.11 PATCHING AND REPAIRS A. It is the intent of these Specifications to require that forms, mixture of concrete and workmanship shall be such that concrete surfaces, when exposed, will require minimal finishing as specified in Paragraph 3.05 above. B. As soon as the forms have been stripped and the concrete surfaces exposed, fins and other projections shall be removed, recesses left by the removal of form ties (except where ties are left in place during sandblasting) shall be filled and surface defects which do not impair structural strength shall be repaired. Clean all exposed concrete surfaces and adjoining work stained by leakage of concrete, to approval of the Engineer. C. Immediately after removal of forms remove plugs and break off metal ties as required by Paragraph 3.06. Holes are then to be promptly filled upon- stripping as follows: Moisten the hole with water, followed by a 1/16 inch brush coat of neat cement slurry mixed to the consistency of a heavy paste. Immediately plug the holes with 1 1.5 mixture of cement and concrete sand mixer slightly damp to the tough (just short of "balling "). Hammer the grout into the hole until dense, and an excess of paste appears on the surface in the form of a spider web. Trowel smooth with heavy pressure. Avoid burnishing. D. Rub lightly with a fine carborundum stone at an age of I to 5 days if necessary to bring the surface down with the parent concrete. Exercise care to avoid damaging or straining the virgin skin of the surrounding parent concrete. Wash thoroughly to remove all rubbed matter. E. Defective concrete and honeycombed areas shall be chipped reasonably square and at least 1 inch deep to sound concrete by means of hand chisels or pneumatic chipping hammers. Irregular voids or surface stones need not be removed ifthey are sound, free of laitance, and firmly embedded in the parent concrete, subject to Engineer's final inspection. If honeycomb exists around reinforcement, chip to provide a clear space at least 3/8 inch wide all around the steel. For areas less than 1 1/2 inch deep, the patch may be made in the same manner as described above for filling for tie holes, care being exercised to use adequately dry (non - trowelable) mixtures and to avoid sagging. Thick repairs will require buildup in successive 1 1/2 inch layers on successive days, each layer being applied(with slurry, etc.) as described above. To aid strength and bonding of the multiplelayer repairs, the Engineer may order the use of Embeco non - shrink, metallic aggregate 06/07 03300 -12 0,4197