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J <br />t <br />C <br />k <br />C <br />0 <br />n <br />L, <br />0 <br />06/07 <br />D. When high - early- strength Portland cement is permitted, the same strength <br />requirements shall apply except that the indicated strengths shall be attained at <br />seven (7) days instead of twenty -eight (28) days. <br />E. If during the progress of the work it is impossible to secure concrete of the required <br />workability and strength with the materials being furnished, the Engineer may order <br />such changes in proportions or materials, or both, as may be necessary to secure <br />the desired properties. All changes so ordered shall be made at the Contractor's <br />expense. <br />F. If during the progress of the work the Contractor desires to use materials other <br />than those originally approved, or if the materials from the sources originally <br />approved change in characteristics, the Contractor shall, at his own expense, have <br />made new acceptance tests of aggregates and establishment of new basic <br />mixtures and submit them to the Engineer for approval. <br />G. Consistency of the concrete as measured by the ASTM Designation C143 shall be <br />as shown in (Table B). <br />TABLE B <br />Portion of Structure <br />Slump (inches) <br />Max.* Min. <br />Pavement and slabs on ground 3 2 <br />Plain footings, gravity walls, <br />slabs and beams 3 2 <br />Heavy reinforced foundation <br />walls and footings 4 2 <br />Thin reinforced walls and columns 4 2 <br />May be increased 1 -inch if proper method of consolidation is used. <br />H. Concrete shall be of such consistency and mix composition that it can be readily <br />worked into the corners and angles of the forms and around the reinforcement, <br />inserts, and wall castings without permitting materials to segregate or free water to <br />collect on the surface, due consideration being given to the methods of placing and <br />compacting. <br />No excessively wet concrete will be permitted, and if at any time concrete of such <br />consistency beyond the limits of Table B is delivered to the job, the Engineer may <br />direct the Contractor to reject same or to add extra cement for which no additional <br />payment will be made. A supply of the approved cement shall be kept available at <br />the site for this purpose. Drivers of transit -mix trucks shall add no additional water <br />except that established for the design. Failure to comply with this requirement <br />shall be justification for rejecting the concrete. <br />The entrained air, as measured by the Pressure Method, ASTM C231, shall be as <br />shown in (Table C). <br />Nominal Maximum Size <br />of Coarse Ag-gregate(in) <br />TABLE C <br />03300 -3 <br />Total Air Measured at <br />Discharge from truck M <br />03 -4197 <br />