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r-, . ,., . TABLE 6 Property Target Range Tolerance Slump (Non-Drilled Shaft Concrete without :t 0.75 inch [:t20 mm] :t 1.5 inch [:t40 HRWR) mm] Slump (Non-Drilled Shaft Concrete with 1 .0 inch [:t25 mm] :t 1.5 inch [:t40 :t HRWR) mm] Slump (Drilled Shaft Concrete) 1.0 inch [:J:25 mm] :t 1.0 inch [:t25 :t mm] Air Content As shown in the range in Table 2 ..., . .., . " . r"1 Reject concrete with slump or air content exceeding the above tolerances. Do not allow concrete to remain in a transporting vehicle to reduce slump. Water may be added only upon arrival of the concrete to the job site and not thereafter. If the slump of non-drilled shaft concrete varies from the target value in excess of 0.75 inch [20 mm] (1 inch [25 mm] for concrete containing HRWR), immediately adjust the concrete mixture to correct the slump of succeeding batches. The Engineer will allow a reasonable time for adjustment, taking into consideration trucks already in route from the concrete production facility. If the Contractor does not implement adjustments at the earliest possible time, the Engineer will reject the concrete and terminate further production until the Contractor makes corrections. . ., . Ii . ,., . 346-7 Mixing and Delivering Concrete. 346-7.1 General Requirements: Operate all concrete mixers at speeds and volumes per the manufacturer's design or recommendation as stipulated on the mixer rating plate. 346-7.2 Transit Mixing: When water is added at the job site, mix the concrete 30 additional mixing revolutions. When mixing for the purpose of adjusting consistency, do not allow the total number of revolutions at mixing speed to exceed 160. Discharge all concrete from truck mixers before total drum revolutions exceed 300. 346-7.3 Mixing at the Site: Use a mixer of sufficient capacity to prevent delays that may be detrimental to the quality of the work. Ensure that the accuracy of batching equipment is in accordance with requirements of this Section. 346-7.4 Concreting in Cold Weather: Do not mix concrete when the air temperature is below 450F [7OC] and falling. The Contractor may mix and place concrete when the air temperature in the shade, and away from artificial heat, is 400F [40C] and rising. Protect the fresh concrete from freezing until the concrete reaches a minimum compressive strength of 1,500 psi [10 MPa] unless the concrete is to be heat cured. 346-7.5 Concreting in Hot Weather: Hot weather concreting is defined as the production, placing and curing of concrete when the concrete temperature at placing exceeds 850F [300C] but is less than 1000F [40oC]. Unless the specified hot weather concreting measures are in effect reject concrete exceeding 850F [300C] at the time of placement. Regardless of special measures taken, reject concrete exceeding 1000F [40oC]. Predict the concrete temperatures at placement time and implement hot weather measures to avoid production shutdown. 346-7.6 Transit Time: Ensure compliance with the following maximum allowable time between the initial introduction of water into the mix and depositing the concrete in place: " . ., . ,.., . ..., . ,., . ., . ,..., . II . .... . -.. 09/09 01000-100 03-4122.F -