Conducted by the Plainfield Division of Worthington Corporation, the major objective of the test was to provided more reliable data on truck mixer performance on the low slump harsh batches required for concrete used in paving work. The investigators hoped to arm ready mix producers with firm data which may be used as an accurate guide for producing concretes which will readily meet the stiff specifications which are being written today. The immediate objective was to study the performance of truck mixers of the inclined axis type when tested under field conditions. The effect of consistency on the time of discharge was of vast importance to both producers and users of ready mixed concrete. The tests indicated that time of discharge is fairly constant for slumps greater than 2 inches but that it goes up quite rapidly for slumps less than 2 inches. Some other significant conclusions: good uniformity was obtained when the water was introduced into the mixer at the batching plant. The different methods of measuring uniformity indicated that the minimum of 50 revolutions of the drum are sufficient to produce the uniformity desired.