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1 40-27 BUILDING <br />CAST -IN -PLACE CONCRETE <br />I <br />1 <br />BRPH ARCHITECTS -ENGINEERS, INC. <br />3. Do not use vibrators to transport concrete inside forms. Insert and withdraw <br />vibrators vertically at uniformly spaced locations to rapidly penetrate placed layer <br />and at least 6 inches into preceding layer. Do not insert vibrators into lower <br />layers of concrete that have begun to lose plasticity. At each insertion, <br />limit duration of vibration to time necessary to consolidate concrete and complete <br />embedment of reinforcement and other embedded items without causing mixture <br />constituents to segregate. <br />Deposit and consolidate concrete for floors and slabs in a continuous operation, within <br />limits of construction joints, until placement of a panel or section is complete. <br />1. Consolidate concrete during placement operations so concrete is thoroughly <br />worked around reinforcement and other embedded items and into corners. <br />2. Maintain reinforcement in position on chairs during concrete placement. <br />3. Screed slab surfaces with a straightedge and strike off to correct elevations. <br />4. Slope surfaces uniformly to drains where required. <br />5. Begin initial floating using bull floats. <br />F. Cold -Weather Placement: Comply with ACI 306.1 and as follows. Protect concrete <br />work from physical damage or reduced strength that could be caused by frost, freezing <br />actions, or low temperatures. <br />1. When average high and low temperature is expected to fall below 40 deg F for <br />three successive days, maintain delivered concrete mixture temperature within <br />the temperature range required by ACI 301. <br />2. Do not use frozen materials or materials containing ice or snow. Do not place <br />concrete on frozen subgrade or on subgrade containing frozen materials. <br />3. Use only the specified non -chloride accelerator, do not use calcium chloride or <br />other materials containing more than 0.05% chloride ion, unless approved in <br />mixture designs. <br />G. Hot -Weather Placement: Comply with ACI 301 and as follows: <br />1. Maintain concrete temperature below 90 deg F at time of placement. Chilled <br />mixing water or chopped ice may be used to control temperature, provided water <br />equivalent of ice is calculated to total amount of mixing water. Using liquid <br />nitrogen to cool concrete is Contractor's option. <br />2. Fog -spray forms, steel reinforcement, and subgrade just before placing concrete. <br />Keep subgrade uniformly moist without standing water, soft spots, or dry areas. <br />3. Use the water reducing retarding admixture when high temperatures require a <br />delay in initial setting time. <br />3.8 FINISHING FORMED SURFACES <br />A. Rough -Formed Finish: As -cast concrete texture imparted by form -facing material with <br />tie holes and defects repaired and patched. Remove fins and other projections that <br />exceed specified limits on formed -surface irregularities. <br />1. Apply to concrete surfaces not exposed to view. <br />C06922.001.00 03 30 04 - 13 <br />05-22-14 <br />