Orange County NC Website
Browse       Search
9/2/2020 <br /> <br />32 13 13 CONCRETE PAVING Page 6 of 12 <br />1. Air Content: 4-1/2 percent plus or minus 1-1/2 percent for 1-inchnominal maximum <br />aggregate size. <br />D. Limit water-soluble, chloride-ion content in hardened concrete to 0.15 percent by weight of <br />cement. <br />E. Chemical Admixtures: Use admixtures according to manufacturer's written instructions. <br />1. Use water-reducing admixture in concrete as required for placement and workability. <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): 4000 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 />3. Provide batch ticket for each batch discharged and used in the Work, indicating Project <br />identification name and number, date, mixture type, mixing time, quantity, and amount of <br />water added. <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 />DocuSign Envelope ID: 7D9ACD4F-8F6C-42B6-9ADB-C60032DB6D03