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more homogeneous mixture the minimum allowable mixing time may be <br /> increased. <br /> 3.03 MIXING AND DELIVERY: <br /> A. General: <br /> Concrete placed quantities greater than two cubic yards shall be truck-mixed <br /> concrete, mixed and delivered in accordance with the requirements of ASTM <br /> C94.Concrete deposit shall be completed within 60 minutes after introduction of <br /> water to the mix, except that if a retardant is used such elapsed time shall not <br /> exceed 90 minutes. <br /> B. Site Mixing: Mixing of batches two cubic yards and more shall continue 60 seconds <br /> plus 15 seconds plus 5 seconds for each cubic yard in excess of two cubic yards. <br /> The mixing time may be reduced to a period of not less than 60 seconds if it is <br /> demonstrated to the satisfaction of the Engineer that a shorter mixing time results in <br /> satisfactory mixing. The mixer shall be operated at the drum speed as stipulated by <br /> the manufacturer of the mixer. Evidence of satisfactory mixing shall consist of the <br /> variation in slump of samples, taken from the first and last quarters of the <br /> discharge, being not more than 3/4 inch from the average of the two slump <br /> values. <br /> END OF SECTION <br /> 08/12 03305-13 11-4179 <br />