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• Dosage rates shall comply with supplier's recommendations and shall <br />be adjusted to account for expected length of time for placement, <br />ambient air temperature and any other relevant conditions. Con- <br />tractor shall submit product data, certification of compliance with <br />ASTM C494 and recommended dosage rates to the Engineer with the <br />concrete mix design. <br />3. The concrete shall be deposited in the forms as nearly as practicable <br />in its final position, so as to avoid rehandling. Special care shall be <br />exercised to prevent splashing the forms or reinforcement with <br />concrete in advance of pouring. <br />4. Immediately after depositing, the concrete shall be compacted by <br />thoroughly agitating the plastic mass, in a manner approved by the <br />Engineer, that will force out all air pockets and work the mixture into <br />corners, around reinforcement and inserts, and prevent the formation <br />of voids. <br />5. Concrete shall not be placed on concrete which has hardened suf- <br />ficiently to cause the formation of seams and planes of weakness <br />within the section. Concrete shall not be allowed to drop freely more <br />than 5 feet. <br />B. Cold-Weather Placement <br />• 1. Concrete shall be mixed and placed when the temperature is at least <br />~ 40 F., and risi unless <br />ng, . permission to pour is obtained from the <br />-' Engineer, in which event all material shall be heated and otherwise <br />_ properly prepared so the hatching and mixing can proceed in full <br />accord with the provisions of this Specification. <br />2. Suitable means shall be pr8vided for maintaining the concrete at a <br />temperature of at least 50 F. for a period of 72 hours after placing, <br />except that where high-early-strength cement is used, this period <br />may be reduced to 24 hours. <br />a. Salt, chemicals or other materials shall NOT be mixed with the <br />concrete for the purpose of preventing freezing. <br />b. Accelerating agents shall NOT be used. <br />C. Earth-Foundation Placement <br />1. Concrete footings shall be placed upon undisturbed, clean surfaces, <br />free from frost, ice, mud, standing or running water. <br />2. When the foundation is on dry soil, waterproof sheathing paper shall <br />be laid over the earth surfaces to receive the concrete. <br />• D. Slabs on Grade <br />03300-7 <br />