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DocuSign Envelope ID:AOF53191-262C-4CB2-B674-9AB9C758A904 <br /> manner to avoid inclined construction joints. <br /> 2. Consolidate placed concrete with mechanical vibrating equipment according to ACI 301. <br /> 3. Do not use vibrators to transport concrete inside forms.Insert and withdraw vibrators vertically at <br /> uniformly spaced locations to rapidly penetrate placed layer and at least 6 inches into preceding <br /> layer.Do not insert vibrators into lower layers of concrete that have begun to lose plasticity.At <br /> each insertion,limit duration of vibration to time necessary to consolidate concrete and complete <br /> embedment of reinforcement and other embedded items without causing mixture constituents to <br /> segregate. <br /> D. Deposit and consolidate concrete for floors and slabs in a continuous operation,within limits of <br /> construction joints,until placement of a panel or section is complete. <br /> 1. Consolidate concrete during placement operations so concrete is thoroughly worked around <br /> 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 or darbies to form a uniform and open-textured surface <br /> plane,before excess bleedwater appears on the surface.Do not further disturb slab surfaces before <br /> starting finishing operations. <br /> E. Cold-Weather Placement: Comply with ACI 306.1 and as follows.Protect concrete work from physical <br /> damage or reduced strength that could be caused by frost,freezing actions, or low temperatures. <br /> 1. When average high and low temperature is expected to fall below 40 deg F for three successive <br /> days,maintain delivered concrete mixture temperature within the temperature range required by <br /> ACI 301. <br /> 2. Do not use frozen materials or materials containing ice or snow.Do not place concrete on frozen <br /> subgrade or on subgrade containing frozen materials. <br /> 3. Do not use calcium chloride,salt,or other materials containing antifreeze agents or chemical <br /> accelerators unless otherwise specified and approved in mixture designs. <br /> F. Hot-Weather Placement: Comply with ACI 305.1 and as follows: <br /> 1. Maintain concrete temperature below 90 deg F at time of placement.Chilled mixing water or <br /> chopped ice may be used to control temperature,provided water equivalent of ice is calculated to <br /> total amount of mixing water.Using liquid nitrogen to cool concrete is Contractor's option. <br /> 2. Fog-spray forms,steel reinforcement,and subgrade just before placing concrete.Keep subgrade <br /> uniformly moist without standing water,soft spots,or dry areas. <br /> 3.8 FINISHING FLOORS AND SLABS <br /> A. General: Comply with ACI 302.1R recommendations for screeding,restraightening,and finishing <br /> operations for concrete surfaces.Do not wet concrete surfaces. <br /> B. Broom Finish:Apply a broom finish to exterior concrete platforms,steps,ramps,and elsewhere as <br /> indicated. <br /> 1. Immediately after float finishing,slightly roughen trafficked surface by brooming with fiberbristle <br /> broom perpendicular to main traffic route. Coordinate required final finish with Owner. <br /> before application. <br /> 3.9 MISCELLANEOUS CONCRETE ITEMS <br />