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CONCRETE IMPROVEMENTS 02 5500- <br />4 <br /> <br />2.03 CEMENT FOR PORTLAND CEMENT CONCRETE <br />A. Cement for Portland Cement Concrete to be placed in roadway improvements <br />such as curbs, gutters, walks, valley gutters, driveways, surface and subsurface <br />pads or slabs shall conform to the requirements of Section 90-2.02B of the State <br />Standard Specification. shall be Type V or Type II (modified) cement conforming <br />to the requirements of ASTM Designation C150, with the following modifications: <br />1. The cement shall not contain more than 0.60% by weight of alkalies, <br />calculated as the percentage of Na20 plus 0.658 times the percentage of K20 <br />when determined by either direct 4 intensity flame photometry or by the <br />atomic absorption method. The instrument and procedure used shall be <br />qualified as to precision and accuracy in accordance with the requirements <br />of ASTM Designation C114. <br />2. The autoclave expansion shall not exceed 0.50%. <br />3. Mortar, containing the Portland Cement to be used and the sand, when <br />tested in accordance with Test Method No. Calif 527, shall not expand in <br />water more than 0.010% and shall have an air content less than 048%. <br />4. Allowable tri-calcium Aluminate (C3A) by weight shall not exceed 5%. <br />Allowable tetracalcium alumino ferrite plus twice the tricalcium aluminate <br />(C4AF+2C3A) by weight shall not exceed 25%. The sulfate expansion test <br />(ASTM C452) may be used in lieu of the above chemical requirements, <br />provided the sulfate expansion does not exceed 0.040% at 14 days (max). <br />5. The Contractor may substitute pozzolan for Portland Cement in amounts up <br />to 15% of the required mix unless high early strength concrete is specified. <br />Pozzolan shall consist of Class F fly ash meeting the requirements of ASTM <br />C618. <br />B. Cement for Portland Cement Concrete to be placed in surface improvements shall <br />contain a coloring compound equivalent to 1/4 pound of lampblack per cubic yard, <br />added to the concrete at the central mixing plant. <br />C. Liquiblack, as supplied by Concrete Corporation of Redwood City, California, may <br />be used in lieu of lampblack. One pint of liquiblack shall be considered equal to <br />one pound of lampblack. <br />2.04 CLASSIFICATION OF PORTLAND CEMENT CONCRETE <br />A. Portland Cement Concrete shall be classified Class "A" or according to the <br />compressive strength requirements specified in Section 90 of the State Standard <br />Specifications.Unless otherwise specified, concrete curbs, gutters, valley gutters, <br />sidewalk, driveways, and curb ramps shall be constructed of Minor Concrete per <br />Caltrans Section 40, “Portland Cement Concrete Pavement”; Section 73 "Concrete <br />Curbs and Sidewalks" and Section 90, "Portland Cement Concrete", of the <br />Caltrans Standard Specifications, except as modified herein. All concrete mixes <br />shall meet Low Carbon Concrete Code Compliance Pathway. Minor Concrete shall <br />provide a minimum compressive strength of 3500 pounds per square inch at <br />twenty-eight (28) days <br />B. Portland Cement Concrete not conforming to the above classification or having <br />required minimum compressive strengths other than those set forth above, shall <br />conform to requirements to be set forth for same noted on the plans or detail <br />drawings. <br />7.A. - Page 23 of 121 <br />29