Orange County NC Website
Browse       Search
DocuSign Envelope ID: 313DA256 -1EDE- 4396- A716- 4C53B809027E <br />JERRY M. PASSMORE CENTER ADDITION AND RENOVATION <br />HILLSBOROUGH, NORTH CAROLINA <br />F. Deposit and spread concrete in a continuous operation between transverse joints. Do not push <br />or drag concrete into place or use vibrators to move concrete into place. <br />G. Consolidate concrete according to ACI 301 (ACI 301M) by mechanical vibrating equipment <br />supplemented by hand spading, rodding, or tamping. <br />Consolidate concrete along face of forms and adjacent to transverse joints with an <br />internal vibrator. Keep vibrator away from joint assemblies, reinforcement, or side <br />forms. Use only square -faced shovels for hand spreading and consolidation. Consolidate <br />with care to prevent dislocating reinforcement and joint devices. <br />H. Screed paving surface with a straightedge and strike off. <br />I. Commence initial floating using bull floats or darbies to impart an open - textured and uniform <br />surface plane before excess moisture or bleed water appears on the surface. Do not further <br />disturb concrete surfaces before beginning finishing operations or spreading surface treatments. <br />Curbs and Gutters: Use design mixture for automatic machine placement. Produce curbs and <br />gutters to required cross section, lines, grades, finish, and jointing. <br />K. Slip -Form Paving: Use design mixture for automatic machine placement. Produce paving to <br />required thickness, lines, grades, finish, and jointing. <br />Compact subbase and prepare subgrade of sufficient width to prevent displacement of <br />slip -form paving machine during operations. <br />L. Cold- Weather Placement: Protect concrete work from physical damage or reduced strength that <br />could be caused by frost, freezing, or low temperatures. Comply with ACI 306.1 and the <br />following: <br />1. When air temperature has fallen to or is expected to fall below 40 deg F (4.4 deg C), <br />uniformly heat water and aggregates before mixing to obtain a concrete mixture <br />temperature of not less than 50 deg F (10 deg C) and not more than 80 deg F (27 deg C) <br />at point of placement. <br />2. Do not use frozen materials or materials containing ice or snow. <br />3. Do not use calcium chloride, salt, or other materials containing antifreeze agents or <br />chemical accelerators unless otherwise specified and approved in design mixtures. <br />M. Hot - Weather Placement: Comply with ACI 301 (ACI 301M) and as follows when hot - weather <br />conditions exist: <br />1. Cool ingredients before mixing to maintain concrete temperature below 90 deg F (32 <br />deg C) at time of placement. Chilled mixing water or chopped ice may be used to control <br />temperature, provided water equivalent of ice is calculated in total amount of mixing <br />water. Using liquid nitrogen to cool concrete is Contractor's option. <br />2. Cover steel reinforcement with water - soaked burlap so steel temperature will not exceed <br />ambient air temperature immediately before embedding in concrete. <br />3. Fog -spray forms, steel reinforcement, and subgrade just before placing concrete. Keep <br />subgrade moisture uniform without standing water, soft spots, or dry areas. <br />CONCRETE PAVING 321313-9 <br />