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VI <br />Ili, <br />u <br />IL <br />II <br />moisture test approximately half way through the batching operations and adjust batch <br />proportions accordingly. <br />Ensure that the calibration of the measuring devices of the concrete <br />production facilities meets the requirements of Chapter 531 of the Florida Statutes. At <br />least quarterly, ensure that all scales, meters and other weighing or measuring devices are <br />checked for accuracy by a qualified representative of a scale company registered with the <br />Bureau of Weights and Measures of the Florida Department of Agriculture. Have the <br />accuracy of admixture measuring dispensers certified annually by the admixture supplier. <br />When Volumetric Mixers are used, deliver concrete in accordance with the <br />requirements of Volumetric Mixer Manufactures Bureau (VMMB) and ensure that the <br />vehicle has a VMMB registered rating plate. <br />347 -3.2 Mixers: Ensure that mixers are capable of combining the components of <br />concrete into a thoroughly mixed and uniform mass, free from balls or lumps of <br />cementitious materials, and capable of discharging the concrete uniformly. Operate <br />concrete mixers at speeds per the manufacturer's design. Do not exceed the <br />manufacturer's rated capacity for the volume of mixed concrete in the mixer, mixing drum, <br />or container. <br />347 -3.3 Delivery: The maximum allowable mixing and agitation time of concrete is <br />120 minutes. <br />347 -3.4 Small Quantities of Concrete: With approval of the District Materials <br />Engineer, small quantities of concrete, less than 3 yd' placed in one day and less than <br />0.5 yd placed in a single placement may be accepted using a pre- bagged mixture. The <br />Engineer will verify that the pre- bagged mixture is prepared in accordance with the <br />manufactures recommendations and will meet the requirements of this Specification. <br />347 -4 Control of Quality. <br />347 -4.1 Concrete Mix Design: Before producing any concrete, submit the proposed <br />mix design to the Engineer on a form provided by the Department. Use only concrete mix <br />designs having prior approval of the Engineer. <br />Materials may be adjusted provided that the theoretical yield requirement of <br />the approved mix design is met. Show all required original approved design mix data and <br />batch adjustments and substituted material on the Department concrete delivery ticket. <br />The Engineer may disqualify any concrete production facility for non - compliance with <br />Specification requirements. <br />347 -4.2 Sampling and Testing: The Engineer may sample and test the concrete at <br />their discretion to verify its quality. The minimum 28 -day compressive strength requirement <br />for this concrete is 2,500 psi. <br />347 -4.3 Records: Maintain the following records for review for at least three years <br />after final acceptance of the project: <br />1 . Approved concrete mix designs. <br />2. Materials source (delivery tickets, certifications, certified mill test reports). <br />3. A copy of the scale company or testing agency report showing the <br />observed deviations from quantities checked during calibration of the scales and meters. <br />4. A copy of the documentation certifying the admixture weighing /measuring <br />devices. <br />5. Recent NRMCA, VMMB or Department inspection records certifying the <br />plant or truck can produce concrete and documentation showing that action has been <br />taken to correct deficiencies noted during the inspections. <br />IMarch 2007 01000 -110 <br />E <br />03- 4122.D ` <br />