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2. Ready mixed concrete shall be transported to the site in watertight agitator or mixer trucks loaded not in <br /> excess of rated capacities. Discharge at the site shall be within one(1)hour after charging. <br /> 3. Attention is called to the importance of scheduling and dispatching trucks from the batching point so that they <br /> shall arrive at the site of the work just before the concrete is required, thus avoiding excessive mixing of <br /> concrete while waiting or delays in placing successive layers of concrete in the forms. <br /> 4. Air-entraining and chemical admixtures, if approved, shall be charged into mixer as a solution and dispensed <br /> by an automatic dispenser or similar metering device. Powdered admixtures shall be weighted or measured by <br /> volume as recommended by the manufacturer. <br /> 5. Two or more admixtures may be used in same concrete,provided such admixtures are added separately during <br /> batching sequence. Admixtures used in combination shall retain full efficiency and have no deleterious effect <br /> on concrete or on properties of each other. <br /> 6. Do not add water after the initial introduction of the mixing water for the batch, except at the start of <br /> discharge, when the measured slump of the concrete is less than that specified and no more than 60 minutes <br /> have elapsed from the time of batching to the start of discharge. In this case, water may be added by the <br /> producer in an amount not exceeding that allowed by the producer to achieve the design water/cement ratio. <br /> The drum blades shall then be turned an additional 30 revolutions minimum at mixing speed. Water shall not <br /> be added to the batch at any later time. Concrete may be used as long as it is of such slump that it can be <br /> placed and properly consolidated without the addition of any other water to the batch,but in no case shall the <br /> time between batching and complete discharge exceed 120 minutes. <br /> 7. Water may be added to the concrete at the Project site,subject to the following conditions: <br /> a. Ready-mix plant is notified and approves in writing. <br /> 1 b. Truck tickets indicate maximum amount of water to be added. <br /> C. Water is added in a manner to control volume. <br /> d. Special Inspector is notified,if concrete placement requires inspection. <br /> Reject concrete if water is added and these conditions are not met. <br /> E. To use materials other than those accepted originally,or if the materials from the source originally accepted change <br /> in characteristics, make additional tests with proposed new materials which will verify production of concrete <br /> meeting with the stated requirements without causing objectionable change in the color or appearance of the <br /> structure. Pay the testing agency for these additional tests. Do not use concrete made from such different materials <br /> until the Architect has given his approval. <br /> F. If,during the progress of the work,it is impossible to secure concrete of the required workability and strength with <br /> the materials being furnished by the Vendor,the Architect may order such changes in the proportions or materials, <br /> or both,as may be necessary to secure the desired properties,subject to the stated requirements. Make any changes <br /> so ordered without extra compensation. <br /> 2.04 SOURCE QUALITY CONTROL <br /> A. Proportioning of Design Mixes <br /> 1. Prepare design mixes for each type and application of concrete required. Include in the mix design report <br /> project name, concrete supplier, contractor, number for strengths, compressive strength at 28 days, water- <br /> cement ratio, portion of structure, design temperature, product names, material types and source, aggregate <br /> analysis,proportions and slump. <br /> 03300-5 No.99132-CP2 <br />