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t <br />C� <br />E. Do not permit vibrators to remain in one area long enough to create a <br />cavity. Plunge vibrators into concrete rapidly so as not to spatter forms or <br />create depressions in the lift. <br />3.16 PROTECTION: <br />A. Make arrangements for cooling and shading concrete in advance of <br />placement, adequate to maintain the required temperature and moisture <br />conditions without injury due to concentration of heat. <br />B. Concrete shall have a maximum placing temperature which will not cause <br />difficulty from loss of slump, flash set, or cold joints. <br />C. The temperature of concrete as placed shall not exceed 95 degrees F. <br />When the temperature of the concrete reinforcement is greater than 120 <br />degrees F, spray with water immediately prior to placing concrete. <br />3.17 BONDING: <br />1 <br />t <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />' o „0s <br />A. Provide longitudinal keys at least 1 -❑ inches deep or inclined dowels at <br />least 12 inches long at all joints in walls and between walls and slabs or <br />footing, unless otherwise indicated. <br />B. When indicated or permitted, obtain bond surface by use of an approved <br />chemical retarder which delays but does not prevent setting of the surface <br />mortar. Remove retarded mortar within 24 hours after placing to produce a <br />clean, exposed coarse aggregate bonding surface. <br />C. After placement has been completed to the construction joint, and before <br />placing fresh concrete, clean reinforcing steel and the surfaces of horizontal <br />and vertical construction joints of surface laitance, curing compound, and <br />other materials foreign to the concrete, and expose clean coarse aggregate <br />of at least 3/8 inch size. Clean hardened concrete surfaces, by abrasive <br />blast methods to expose coarse aggregate, after the curing period or <br />immediately before placing concrete at the joint. Surface of concrete, which <br />has been in place not more than eight hours, may be cleaned with air and <br />water jets if surface laitance is removed and clean coarse aggregate is <br />exposed. Surfaces of horizontal construction joints, where expansion joint <br />filler or bond breaking compound is to be placed as indicated, shall be <br />cleaned of dirt, sawdust, and other loose materials. Moisten surfaces on <br />which concrete is to be placed immediately before placing concrete. <br />D. When new concrete is shown to be joined to existing concrete by means of <br />bar reinforcing steel dowels mortared in holes drilled in the existing <br />concrete, the holes shall be drilled at least 12 inches, blown out, wetted and <br />03300 -17 05 -5564 <br />