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CONCRETE IMPROVEMENTS 02 5500- <br />8 <br /> <br />3.06 PLACING CONCRETE <br />A. Subgrade shall be thoroughly wetted prior to the placing of concrete for all concrete <br />placed directly on soil. All standing water shall be removed prior to placing of <br />concrete. <br />B. No concrete shall be placed until the subgrade and the forms have been approved. <br />C. Concrete shall be conveyed from mixer to final location as rapidly as possible by <br />methods preventing separation of the ingredients. Deposit concrete as nearly as <br />possible in final position to avoid re-handling. <br />D. Concrete shall be placed and compacted in forms without segregation by means <br />of mechanical vibration or by other means as approved by the Engineer. Vibration <br />shall continue until the material is sufficiently consolidated and absent of all voids <br />without causing segregation of material. The use of vibrators for extensive shifting <br />of fresh concrete will not be permitted. <br />E. All control and construction joints shall be as shown on the plans. <br />F. Concrete in certain locations may be pumped into place upon prior approval. <br />When this procedure requires redesign of the mix, such redesign shall be <br />submitted for approval in the same manner as herein specified for approval of <br />design mixes. <br />3.07 FORM REMOVAL <br />A. Forms shall be removed without damage to concrete. All forms below the ground <br />surface, together with all shores and braces, shall be removed before backfilling. <br />B. Backfill against concrete shall not commence until the concrete has developed <br />sufficient strength to prevent damage. <br />C. Forms with cast-in-place walls shall remain in place at least 72 hours after pouring. <br />D. Forms with suspended slabs shall remain in place at least 28 days after pouring. <br />E. Edge forms shall remain in place at least 24 hours after pouring. <br />3.08 EXPANSION JOINTS <br />A. Expansion joints incorporating premolded joint fillers shall be constructed at twenty <br />(20) foot intervals in all concrete curbs, gutters and sidewalks, and at the ends of <br />curb returns. At each expansion joint, one-half by twelve inch (1/2" x 12") smooth <br />slip dowels shall be installed in the positions shown or noted on the detail drawings. <br />B. Slip dowels shall be oriented at right angles to the expansion joint and shall be <br />held firmly in place during the construction process by means of appropriate chairs. <br />C. Expansion joints and slip dowels shall be constructed in valley gutters and <br />driveway approaches in the positions indicated or called for on the detail drawings. <br />3.09 CONTROL JOINTS <br />A. Control joints shall be constructed in concrete curbs, gutters, walkways and <br />pavements between expansion joints at ten (10) foot intervals throughout, or as <br />shown on the plans. Depth of joint score shall be a minimum of one-fourth (25%) <br />the thickness of the concrete. <br />7.A. - Page 27 of 121 <br />33