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' <br />D. <br />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. <br />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 />' <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. <br />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. <br />Consistency of the concrete as measured by the ASTM Designation C143 shall be <br />as shown in (Table B). <br />' <br />TABLE B <br />Slump (inches) <br />Portion of Structure Max.* Min. <br />Pavement and slabs on ground 3 2 <br />Plain footings, gravity walls, <br />' <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. <br />Concrete shall be of such consistency and mix composition that it can be readily <br />t <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 />I. 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 />' J. The entrained air, as measured by the Pressure Method, ASTM C231, shall be as <br />shown in (Table C). <br />' TABLE C <br />Nominal Maximum Size Total Air Measured at <br />of Coarse Aggregate(in) Discharge from truck M) <br />1 05/08 03300 -3 05 -4893 <br />