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<br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />4. Raw water (groundwater) and canal water shall not be allowed in the mix. <br /> <br />E. Admixtures: <br /> <br />I. <br /> <br />A water reducing agent shall be used in all concrete. The admixture shall conform <br />to ASTM Specification C494. Proportioning and mixing shall be as recommended <br />by the manufacturer. <br /> <br />" <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />2. <br /> <br />Admixtures causing accelerated setting of cement in concrete shall not be used. <br />Air entraining admixtures with demonstrated compatibility with the concrete mix <br />shall be used as required as a moderate addition to the water reducing agent to <br />obtain the specified percent air in the resultant concrete. <br /> <br />LJ <br /> <br />n PART 3 - EXECUTION <br /> <br />n <br /> <br />3.01 MEASURING MATERIALS <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />3.02 MIXING <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />n <br /> <br />LJ <br /> <br />06/05 <br /> <br />" <br /> <br />LJ <br /> <br />A. <br /> <br />Materials shall be measured by weighing except as otherwise specified or where other <br />methods are specifically authorized by the Engineer. The apparatus provided for weighing <br />the aggregates and cement shall be suitably designed and constructed for this purpose. <br />Scales shall have been certified by the local Sealer of Weights and Measures within one <br />year of use. Each size of aggregate and the cement shall be weighed separately. The <br />accuracy of all weighing devices shall be such that successive quantities can be measured <br />to within one percent of the desire amount. Cement in standard packages (sacks) need not <br />be weighed, but bulk cement and fractional packages shall be weighed. <br /> <br />B. <br /> <br />Water shall be measured by volume or by weight. The water-measuring device shall be <br />capable of control to 1/2% accuracy. All measuring devices shall be subject to approval. <br />Admixtures shall be dispensed either manually with use of calibrated containers or <br />measuring tanks, or by means of an approved automatic dispenser designed by the <br />manufacturer of the specified admixture. <br /> <br />A. <br /> <br />Concrete shall be ready-mixed or transit-mixed, as produced by equipment acceptable to <br />the Engineer. No hand-mixing will be permitted. Adding water in controlled amounts <br />during the mixing cycle shall be done only with the express approval of, and under the <br />direction of, the Engineer. <br /> <br />B. <br /> <br />Ready-mix or transit-mixed concrete shall be transported to the site in watertight agitator or <br />mixer trucks loaded not in excess of rated capacities for the respective conditions as stated <br />on the name plate. Discharge at the site shall be within 1-1/2 hours and within one hour <br />when ambient temperature is above 85 degree F after cement was first introduced into the <br />mix. Central mixed concrete shall be plant-mixed a minimum of 1-1/2 minutes per batch <br />and then shall be truck-mixed or agitated a minimum of 8 minutes. Agitation shall begin <br />immediately after the pre-mixed concrete is placed in the truck and shall continue without <br />interruption until discharge. Transit-mixed concrete shall be mixed at mixing speed for at <br />least 10 minutes immediately after charging the truck, followed by agitation without <br />interruption until discharged. <br /> <br />c. <br /> <br />All central plant and rolling stock equipment and methods shall conform to the latest Truck <br />Mixer and Agitator Standards of the Truck Mixer Manufacturers' Bureau of the National <br />Ready-Mixed Concrete Association, as well as ACI Standard 304 and ASTM Specification <br />C94. <br /> <br />03300-6 <br /> <br />03-4138.8 <br />