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1 <br /> 3. Potable tap water will normally fulfill the above requirements. <br /> 4. Raw water (groundwater) and canal water shall not be allowed in the mix. <br /> 1 E. Admixtures: <br /> 1. A water reducing agent shall be used in all concrete. The admixture shall <br /> ' conform to ASTM Specification C494. Proportioning and mixing shall be as <br /> recommended by the manufacturer. <br /> 2. Admixtures causing accelerated setting of cement in concrete shall not be <br /> ' used. Air entraining admixtures with demonstrated compatibility with the <br /> concrete mix shall be used as required as a moderate addition to the water <br /> reducing agent to obtain the specified percent air in the resultant concrete. <br /> PART 3 - EXECUTION <br /> 3.01 MEASURING MATERIALS <br /> A. Materials shall be measured by weighing except as otherwise specified or where <br /> other methods are specifically authorized by the Engineer. The apparatus <br /> provided for weighing the aggregates and cement shall be suitably designed and <br /> 1 constructed for this purpose. Scales shall have been certified by the local Sealer <br /> of Weights and Measures within one year of use. Each size of aggregate and the <br /> cement shall be weighed separately. The accuracy of all weighing devices shall be <br /> such that successive quantities can be measured to within one percent of the <br /> desire amount. Cement in standard packages (sacks) need not be weighed, but <br /> bulk cement and fractional packages shall be weighed. <br /> B. Water shall be measured by volume or by weight. The water-measuring device <br /> shall be capable of control to 1/2% accuracy. All measuring devices shall be <br /> subject to approval. Admixtures shall be dispensed either manually with use of <br /> calibrated containers or measuring tanks, or by means of an approved automatic <br /> dispenser designed by the manufacturer of the specified admixture. <br /> 3.02 MIXING <br /> A. Concrete shall be ready-mixed or transit-mixed, as produced by equipment <br /> acceptable to the Engineer. No hand-mixing will be permitted. Adding water in <br /> controlled amounts during the mixing cycle shall be done only with the express <br /> approval of, and under the direction of, the Engineer. <br /> B. Ready-mix or transit-mixed concrete shall be transported to the site in watertight <br /> agitator or mixer trucks loaded not in excess of rated capacities for the respective <br /> conditions as stated on the name plate. Discharge at the site shall be within 1-1/2 <br /> hours and within one hour when ambient temperature is above 85 degree F after <br /> cement was first introduced into the mix. Central mixed concrete shall be <br /> plant-mixed a minimum of 1-1/2 minutes per batch and then shall be truck-mixed <br /> or agitated a minimum of 8 minutes. Agitation shall begin immediately after the <br /> pre-mixed concrete is placed in the truck and shall continue without interruption <br /> until discharge. Transit-mixed concrete shall be mixed at mixing speed for at least <br /> 10 minutes immediately after charging the truck, followed by agitation without <br /> interruption until discharged. <br /> C. All central plant and rolling stock equipment and methods shall conform to the <br /> latest Truck Mixer and Agitator Standards of the Truck Mixer Manufacturers' <br /> 05/08 03300-6 05-4893 <br />