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t under conditions approved by the Engineer. 2 3 B. No concrete shall be placed in the work after it has begun to set. No concrete can be 4 placed more than one hour after it has been mixed. 5 5 C. If transit mix is used, the rate of delivery, haul time, mixing time and hopper capacity shall 1 7 be such that all mixed concrete delivered shall be placed in the forms within one hour from 8 the time of introduction of cement and water to the mixer. All concrete shall be kept 9 continuously agitated until discharged in the hopper at the job site. io 11 D. Ready-mixed concrete shall be batched, mixed, and transported in accordance with ASTM 12 C94 and Chapter 7 of ACI 301. Plant equipment and facilities shall conform to the "Check 13 List for Certification of Ready Mixed Concrete Production Facilities" of the National Ready ' 14 Mixed Concrete Association. is 15 3.04 CONCRETE HANDLING & PLACEMENT ' n 15 A. Excavations and Formwork: 19 20 1. Excavations shall be kept free from water while concrete is being placed, cured and 21 finished therein. Fresh concrete shall be protected at all times from running water. 22 23 2. Before placing concrete, all form work shall be cleaned of dirt and construction debris, ' 24 water-drained, reinforcement securely and properly fastened in its correct position, forms 25 at construction joints re-tightened, all bucks, sleeves, hangers, pipes, conduits, bolts, 25 wires, etc., installed. No concrete shall be placed before the forms and all work that is 27 to be embedded have been set and observed by the Engineer. 2e zs B. Concrete Placement: 30 31 1. The working schedule and schedule of placement shall be as shown on the plans and 32 worked out in conjunction with the Engineer. The schedule shall be worked out prior 33 to commencement of work, and shall be rigidly adhered to. 34 35 2. Concrete shall be conveyed from the mixer to the place of final deposit as rapidly as 38 practicable by methods which will prevent the separation or loss of the materials. The 37 concrete shall be deposited in the forms as nearly as practicable in its final position to ' 38 avoid rehandling. 39 40 3. Concrete shall be placed and consolidated by methods that will not cause segregation 41 of the aggregates and will result in a dense homogeneous concrete which is free of 42 voids and rock pockets. All concrete shall be used while fresh and before it has taken 43 an initial set. Re-tempering any partially hardened concrete with additional water will not 44 be permitted. I 45 as 4. Surfaces on which concrete is to be placed shall be thoroughly moistened with water 47 immediately before placing concrete. 4 499 50 5. Concrete shall not be deposited on frozen or ice-coated ground nor on ice-coated forms, ' St reinforcing steel, embedded items or construction joints. 52 CONCRETE 042894 03100-7