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PGSF WMVD Storm and Combined Sewer - Construction Package 2 Cast-in-Place Concrete <br />Project No. 180162 03 30 00 - 15 <br /> <br />4) Inspection of Tremie Slab Concrete: <br />a) Develop and submit an inspection plan covering locations and methods <br />of taking soundings during the tremie concrete placement. Soundings <br />shall be taken each hour during placement or every 200 cy, whichever <br />results in the most frequency of soundings. Soundings shall be spaced to <br />cover the area at each tremie pipe discharge location. Data obtained <br />from soundings shall be plotted immediately to monitor progress in <br />placement. <br />5) Note that the tremie slab is to be placed 6 inches higher than shown on the <br />drawings followed by removal of the 6 inch excess to ensure quality concrete <br />at the top surface. <br />3.03 CONSOLIDATING CONCRETE <br />A. Consolidate concrete in accordance with ACI 301. If evidence of inadequate <br />consolidation is observed, concrete placement will be suspended until Contractor <br />provides a revised plan to achieve proper consolidation. <br />3.04 CURING AND SEALING <br />A. General: <br />1. Cure concrete using water (including form curing and use of moister retaining <br />covers), a clear membrane curing compound, or by a combination of both methods. <br />Coordinate repairs or treatment of concrete surfaces so that interruption of curing <br />will not be necessary. <br />2. Maintain concrete surface temperature between 50 degrees F and 80 degrees F for <br />at least 5 days. Cure concrete in hot weather (above 80 degrees F) in accordance <br />with ACI 305.1. Cure concrete in cold weather (below 45 degrees F) in accordance <br />with ACI 306.1. <br />B. Water Curing: <br />1. Keep concrete continuously wet for a minimum of 10-days after placement (14 days <br />after placement for sections over 3-feet thick). Absorptive mats or fabric may be used <br />to retain moisture during the curing period. Absorptive covers shall comply with <br />AASHTO M182, Class 3, and moisture retaining covers shall comply with ASTM C171. <br />2. Use water curing in hot weather for liquid containment structures. Cover forms and <br />keep moist. Loosen forms as soon as possible without damage to the concrete, and <br />make provisions for curing water to run down inside them. During form removal, take <br />care to provide continuously wet cover to newly exposed surfaces. <br />C. Curing Compound: <br />1. When curing compound is allowed, apply it as soon as the concrete has set <br />sufficiently so as not to be marred by the application or apply it immediately following <br />form removal for vertical and other formed surfaces. Preparation of surfaces, <br />application procedures, and installation precautions shall follow manufacturer’s <br />instructions. For liquid containing structures, apply curing compound at twice the <br />manufacturer’s recommended dosage rate, applied in two coats perpendicular to <br />each other.