Concrete shall consist of a mixture of Type II Portland Cement, sand, fine aggregate, coarse aggregate and water. The proportions of the water, sand and aggregate shall be regulated so as to produce a plastic, workable and cohesive mixture yielding the strength indicated. Unless noted otherwise, all concrete shall be Class “A”.
(A) Class “A”. Class “A” concrete shall contain 564 pounds (6 sacks) of Portland Cement per cubic yard and shall have a minimum 28-day compressive strength of 4,000 psi in accordance with ASTM C-39.
(B) Class “C”.
(1) Class “C” concrete shall contain 376 pounds (four sacks) of Portland Cement per cubic yard and shall have a minimum 28-day compressive strength of 2,500 psi in accordance with ASTM C-39.
(2) All material required, and the procedure of mixing, shall meet the requirements set forth in § 90 of Caltrans State Standard Specifications, except that three-fourths inch maximum size aggregate shall be used and slump ranges of three to four inches for Class “A” concrete and four to eight inches for Class “C” concrete shall be maintained.
(3) No admixtures will be permitted unless authorized by the Engineer.
(4) Cement and aggregates shall be stored in such a manner as to prevent deterioration or intrusion of foreign matter.
(5) Mixed concrete shall be used before initial set and in no case will re-tempering with additional water be permitted.
(C) Controlled low strength material (CLSM). CLSM shall be flowable, hand-excavatable mixture of cement, pozzolan, coarse and fine aggregate and water which has been mixed in accordance with ASTM C 94. Cement shall be Type II in accordance with ASTM C150. Pozzolan shall be added to improve flowability and shall be Type F in accordance with the requirements of ASTM C618. Coarse aggregate shall consist of a well graded mixture of crushed rock, soil or sand with a maximum size aggregated of one-half inch. One hundred percent shall pass the three-fourths inch sieve. Not more than 30% shall be retained by the three-eighths inch sieve and not more than 12% shall pass the No. 200 sieve. CLSM density shall be between 120 pounds per cubic foot and 135 pounds per cubic foot. Compressive strength at 28 days for flowable CLSM shall be between 50 psi minimum and 150 psi maximum.
(Ord. 2019-02, passed 4-25-2019)