Lab 5 - Compaction Procedure_Final Draft - Tagged

CEE 367 – Lab #5 Proctor test). In 1933, R.R. Proctor published a series of four articles on soil compaction. In the second of this series, he described a laboratory compaction test which is now called the "standard Proctor" compaction test. Table 1, which gives a comparison of some of the common laboratory tests, shows that the amount of compactive energy per volume used in the modified test is over 4.5 times that of the original Proctor test. The methods of compaction along with the field techniques and laboratory simulations are shown in Table 2. The critical question to be asked about any laboratory compaction test is, "How well does it represent field compaction?" Figure 5.4 in Holtz & Kovacs (1981) shows a comparison for a silty clay. For this soil, the laboratory tests indicate optimum mixing water contents which are lower than the actual field optimum; this trend has been observed with most soils. Figure 5.4 also illustrates the difficulty of selecting the proper laboratory test to use for a given soil and field compaction process. Table 1. Comparison of several compaction tests Test Mold Size Hammer Wt. (lbs) No. of Lifts Ht. Of Hammer Drop (in.) No. of Blows per Layer Compactive Energy per Unit Volume (ft-lb/ft 3 ) Standard Proctor 4.6 x 4 in. dia. 5.5 3 12 25 12400 Standard Proctor 5 x 6 in. dia. 5.5 3 12 55 12400 Modified Proctor 4.6 x 4 in. dia. 10 5 18 25 56300 Modified Proctor 5 x 6 in. dia. 10 5 18 55 56000 15 Blow Proctor 4.6 x 4 in. dia. 5.5 3 12 15 7400 15 Blow Proctor 5 x 6 in. dia. 5.5 3 12 35 7800 Table 2. Compaction methods: field techniques and lab simulations Method Lab Simulation Field Technique Impact Standard compaction test Nothing comparable Kneading Harvard miniature apparatus; Hveem method Sheepsfoot roller, wobble wheel; Rubber-tired roller Vibration Vibratory table Vibratory rollers and compactors Static (or dynamic) compression Compression machines Smooth wheel rollers Page 2 of 9