Orange County NC Website
DocuSign Envelope ID:070B6BC7-CDE2-4AO8-BE62-07FA6BFDO53B <br /> 11/20/2020 <br /> 2. Use water-reducing and retarding admixture when required by high temperatures, low <br /> humidity, or other adverse placement conditions. <br /> F. Synthetic Fiber: Uniformly disperse in concrete mixture at manufacturer's recommended rate... <br /> G. Concrete Mixtures:Normal-weight concrete. <br /> 1. Compressive Strength(28 Days): 3000 psi. <br /> 2. Maximum W/C Ratio at Point of Placement: 0.45. <br /> 3. Slump Limit: 4 inches,plus or minus 1 inch. <br /> 2.9 CONCRETE MIXING <br /> A. Ready-Mixed Concrete: Measure, batch, and mix concrete materials and concrete according to <br /> ASTM C 94/C 94M. Furnish batch certificates for each batch discharged and used in the Work. <br /> 1. When air temperature is between 85 and 90 deg F, reduce mixing and delivery time from <br /> 1-1/2 hours to 75 minutes; when air temperature is above 90 deg F, reduce mixing and <br /> delivery time to 60 minutes. <br /> B. Project-Site Mixing: Measure, batch, and mix concrete materials and concrete according to <br /> ASTM C 94/C 94M. Mix concrete materials in appropriate drum-type batch machine mixer. <br /> 1. For concrete batches of 1 cu.yd.or smaller,continue mixing at least 1-1/2 minutes,but not <br /> more than 5 minutes after ingredients are in mixer,before any part of batch is released. <br /> 2. For concrete batches larger than 1 cu. yd., increase mixing time by 15 seconds for each <br /> additional 1 cu. yd.. <br /> PART 3 -EXECUTION <br /> 3.1 EXAMINATION <br /> A. Examine exposed subgrades and subbase surfaces for compliance with requirements for <br /> dimensional, grading, and elevation tolerances. <br /> B. Proof-roll prepared subbase surface below concrete paving to identify soft pockets and areas of <br /> excess yielding. <br /> 1. Completely proof-roll subbase in one direction [and repeat in perpendicular direction]. <br /> Limit vehicle speed to 3 mph. <br /> 2. Proof-roll with a pneumatic-tired and loaded, 10-wheel,tandem-axle dump truck weighing <br /> not less than 15 tons. <br /> 3. Correct sub-base with soft spots and areas of pumping or rutting exceeding a depth of 1/2 <br /> inch according to requirements in Division 31 Section "Earth Moving" <br /> C. Proceed with installation only after unsatisfactory conditions have been corrected. <br /> 32 13 13 CONCRETE PAVING Page 6 of 11 <br />