ACI 311.5-04 Guide for Concrete Plant Inspection and Testing of Ready-Mixed Concrete

ACI 311.5-04 Guide for Concrete Plant Inspection and Testing of Ready-Mixed Concrete. 2.4—Duties 2.4.1 The field technician should check each delivery ticket to verify that the mixture with the correct designation is being delivered and, if possible, determine whether adjust- ments to proportions, such as admixtures, have been made. Immediate action should be taken, as authorized, in the case of a discrepancy. Immediate verbal notification should be given to the placing contractor and the concrete supplier. 2.4.2 The field technician should determine that: • Truck mixers are not loaded in excess of mixer plate capacity; • Concrete appears to be uniform and adequately mixed before discharge at the project site; • Field additions of water, admixtures, or fiber reinforce- ment are properly conducted and documented; • Concrete delivery and placement falls within the time constraints of the project specifications; and • All data required by ASTM C 94/C 94M, the purchaser, or the job specification are included on the delivery ticket. Immediately report any discrepancies to the placing contractor and the concrete supplier. 2.4.3 The technician should cast at least one set of strength test specimens in accordance with ASTM C 31/C 31M for each 100 yd 3 (76 m 3 ), or fraction thereof, of each class of concrete placed in any one day. Tests of concrete that should be conducted whenever strength specimens are cast include the following: slump, air content, temperature, and density (whenever yield is to be calculated or as required by project specifications). When sampling concrete, a composite sample repre- senting concrete conditions as delivered to the forms should be obtained in accordance with ASTM C 172, and the date, time, placement location, truck number, and ticket number should be reported. 2.4.12 In accordance with ASTM C 31/C 31M, the testing laboratory should pick up and transport specimens cast for acceptance testing within 16 to 48 h after molding. If the specimens are not transported to the laboratory within 48 h, the molds should be removed within 16 to 32 h, and the spec- imens should be moist cured at 73 ± 3 ºF (23 ± 2 ºC) until they are transported. The transportation time should not exceed 4 h. Specimens should be protected from damage, moisture loss, and freezing during transport. Within 30 min after removal from the molds, the specimens should be stored at a temperature of 73 ± 3 ºF (23 ±...