Figure 21. Concrete delivered by revolving-drum truck 

 (photo courtesy of Los Angeles Harbor 

 Department] . 



has proper plastic physical properties, and the concrete is of adequate 

 consistency and homogeneity for satisfactory placement and consolidation. 

 This latter approach is favored specifically with regard to maximum allow- 

 able time for discharge, and is particularly applicable when cool concrete 

 temperatures are used or when cooler weather prevails. Final determination 

 of whether mixing is being accomplished satisfactorily should be based on 

 standard mixer uniformity tests (ASTM Standard C94-81) . 



(3) Revolving Drum . By this method, the mixer serves as an 

 agitating transportation unit. The drum is rotated at charging speed 



140 



