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<br />03300 - 16/22 <br />2. The surface of the concrete shall be level whenever a run of concrete is <br />stopped. To insure a level, straight joint on the exposed surface of walls, a <br />wood strip at least 3/4-inch thick shall be tacked to the forms on these <br />surfaces. The concrete shall be carried about 1/2-inch above the underside of <br />the strip. About one hour after the concrete is placed, the strip shall be <br />removed and any irregularities in the edge formed by the strip shall be leveled <br />with a trowel and laitance shall be removed. <br />3.06 TAMPING AND VIBRATING: <br />A. As concrete is placed in the forms or in excavations, it shall be thoroughly settled <br />and compacted throughout the entire depth of the layer which is being consolidated, <br />into a dense, homogeneous mass, filling all corners and angles, thoroughly <br />embedding the reinforcement, eliminating rock pockets, and bringing only a slight <br />excess of water to the exposed surface of concrete. Vibrators shall be Group 3 per <br />ACI 309, high speed power vibrators (8000 to 12,000 rpm) of an immersion type in <br />sufficient number and with at least one standby unit as required. Group 2 vibrators <br />may be used only at specific locations when accepted by the ENGINEER. <br />B. Care shall be used in placing concrete around waterstops. The concrete shall be <br />carefully worked by rodding and vibrating to make sure that all air and rock pockets <br />have been eliminated. Where flat-strip type waterstops are placed horizontally, the <br />concrete shall be worked under the waterstops by hand, making sure that air and <br />rock pockets have been eliminated. Concrete surrounding the waterstops shall be <br />given additional vibration over and above that used for adjacent concrete placement <br />to assure complete embedment of the waterstops in the concrete. <br />C. Concrete in walls shall be internally vibrated and at the same time rammed, stirred, <br />or worked with suitable appliances, tamping bars, shovels, or forked tools until it <br />completely fills the forms or excavations and closes snugly against all surfaces. <br />Subsequent layers of concrete shall not be placed until the layers previously placed <br />have been worked thoroughly. Vibrators shall be provided in sufficient numbers, with <br />standby units as required, to accomplish the required results within 15 minutes after <br />concrete of the prescribed consistency is placed in the forms. The vibrating head <br />shall not contact the surfaces of the forms. Care shall be taken not to vibrate <br />concrete excessively or to work it in any manner that causes segregation of its <br />constituents. <br /> <br />3.07 CURING AND DAMPPROOFING: Concrete shall be cured for a minimum of five (5) days <br />after placement in accordance with the methods indicated below for the different parts of <br />the WORK. <br /> <br />A. The surface shall be sprayed with a liquid curing compound. <br />1. It shall be applied in accordance with the manufacturer's printed instructions at <br />a maximum coverage rate of 200 square feet per gallon and in such a manner <br />as to cover the surface with a uniform film that will seal thoroughly. <br />2. Where the curing compound method is used, care shall be exercised to avoid <br />damage to the seal during the 7-day curing period. If the seal is damaged or <br />broken before the expiration of the curing period, the break shall be repaired