Laserfiche WebLink
<br />03300 - 10/22 <br /> <br />E. Adjustments to Mix Design: The CONTRACTOR may elect to decrease the <br />water/cement ratio to achieve the strength and shrinkage requirements and/or add <br />water reducers, as required to achieve workability. The mixes shall be changed <br />whenever such change is necessary or desirable to secure the required strength, <br />density, workability, and surface finish, and the CONTRACTOR shall be entitled to no <br />additional compensation because of such changes. Any changes to the accepted <br />concrete mix design shall be submitted to the ENGINEER for review and shall be <br />tested again in accordance with these Specifications. <br />F. When using a floor hardener the water/cement ratio shall not be greater than <br />specified by the hardener manufacturer. <br />2.09 CONSISTENCY: <br />A. The quantity of water in a batch of concrete shall be just sufficient, with a normal <br />mixing period, to produce a concrete which can be worked properly into place <br />without segregation and which can be compacted by vibratory methods to give the <br />desired density, impermeability, and smoothness of surface. The quantity of water <br />shall be changed as necessary, with variations in the nature or moisture content of <br />the aggregates, to maintain uniform production of a desired consistency. The <br />consistency of the concrete in successive batches shall be determined by slump <br />tests in accordance with ASTM C 143 The slumps shall be as follows: <br />Part of Work Slump (in) <br />All concrete, unless indicated <br />otherwise <br />3-inches plus or minus 1-inch <br />With high range water reducer <br />added <br />7-inches plus or minus 2-inches <br />Pea gravel mix 7-inches plus or minus 2-inches <br />Ductbank and pipe encasement 5-inches plus or minus 1-inch <br />Concrete with hardener Per Hardener Manufacturer <br />2.10 MEASUREMENT: <br />A. The amount of cement and of each separate size of aggregate entering into each <br />batch of concrete shall be determined by direct weighing equipment furnished by the <br />CONTRACTOR and acceptable to the ENGINEER. <br />B. Weighing tolerances <br />Material Percent of Total <br />Weight <br />Cement 1 <br />Aggregates 3 <br />Admixtures 3 <br />C. The quantity of water entering the mixer shall be measured by a suitable water meter <br />or other measuring device of a type acceptable to the ENGINEER and capable of <br />measuring the water in variable amounts within a tolerance of one percent. The <br />water feed control mechanism shall be capable of being locked in position so as to <br />deliver constantly any required amount of water to each batch of concrete. A positive <br />quick-acting valve shall be used for a cut-off in the water line to the mixer. The <br />operating mechanism shall prevent leakage when the valves are closed.