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Knight Resold <br /> G O N S Y L T 1 N O <br /> <br /> 384 The batch shall be so charged into the drum that a portion of the mixing water shall enter in <br /> 385 advance of the cement and aggregates. The flow of water shall be uniform and all water shall <br />' 386 be in the drum by the end of the first 15 seconds of the mixing period. The throat of the drum <br /> 387 shall be kept free of such accumulations as may restrict the free flow of materials into the <br /> 388 drum. <br /> 389 <br /> 390 The timing device on stationary mixers shall be equipped with a bell or other suitable <br /> 391 warning device adjusted to give a cleazly audible signal each time the lock is released. In <br /> 392 case of failure of the timing device, the Contractor will be permitted to operate while it is <br /> 393 being repaired, provided the Contractor furnishes an approved timepiece equipped with <br /> 394 <br />395 minute and second hands. If the timing device is not placed in good working order within 24 <br />hours, further use of the mixer will be prohibited until repairs are made. <br /> 396 <br /> 397 <br />398 (c) Truck Mixing. Truck mixed concrete shall conform with one of the following: <br /> 399 1. Concrete mixed entirely in a truck mixer equipped with a mechanical counter shall be <br /> 400 <br />401 partially mixed at the plant or in transit for not less than 20 revolutions of the drum at <br />mixing speed. The revolutions of the drum at charging speed shall not be counted as <br /> 402 mixing revolutions. The concrete shall be mixed between 50 and 100 revolutions of the <br /> 403 mixer drum at mixing speed at the delivery site before discharge of the concrete. <br /> 404 <br /> 405 2. Concrete partially mixed in a stationary central mixing plant with mixing brought to <br /> 406 completion in a truck mixer (known as shrink mixing) shall be mixed for a minimum of <br /> 407 30 seconds in the stationazy mixer. Mixing shall be completed in the truck mixer for at <br /> 408 least 20 but not more than 100 revolutions of the mixer drum at mixing speed at the <br /> 409 delivery site before dischazge of the concrete. <br /> 410 <br /> 411 3. Concrete mixed entirely in a stationary mixer and delivered to the job in a truck mixer <br /> 412 shall be remixed for a minimum of 20 revolutions of the mixing drum at mixing speed at <br /> 413 the job site prior to dischazge. <br /> 414 <br /> 415 When water is added at the delivery site to control the consistency of the concrete as <br /> 416 specified in subsection 601.02, the concrete shall be mixed for at least 20 revolutions of <br /> 417 the mixer drum at mixing speed for each addition of water before discharge. These <br />' 418 revolutions aze in addition to the minimum revolutions required for mixing at the delivery <br /> 419 site. The added water shall not cause the water/cement ratio to exceed the requirements in <br /> 420 subsection 601.02. Water from all sources shall be documented by the ready mix <br /> 421 producer on the delivery slip for each load of concrete. <br /> 422 <br /> 423 The Contractor shall provide a Concrete Truck Mixer Certification. This certification <br /> 424 shall show the various pick-up and throw-over configurations and wear mazks so that the <br /> 425 wear on the blades can be checked. Blades shall be replaced when any part or section is <br /> 426 worn 1 inch or more below the original height of the manufacturer's design. A copy of <br /> 427 the manufacturer's design, showing the dimensions and arrangement of blades, shall be <br /> 428 available to the Engineer at all times. <br /> <br /> 3-39 <br /> G.H011001 W.02N\ReportslKP\Tachniral Specilcations.tloc Fepnary 3, 2006 <br /> <br />