Chapter 3: Phase I Test Box and Test Pit 3.1 Phase I Testing Plan 3.1 Phase I Testing Plan
4. DCP 5. DSPA
3.3 Phase I Testing .1 Test Series 1 and 2 .1 Test Series 1 and 2
3.3 Phase I Testing 3.3.1 Test Series 1 and 2
One of the goals of the first round of tests is to determine the depth of influence for each
apparatus. To prepare the test box for these initial tests series, soil is mixed with water, brought to its optimum moisture content, added to the test box, and compacted to a lift thickness of 8 in.
A test series is conducted where several pieces of equipment are tested. Next, another 8-in.
compacted lift is added to the test box. A second test series is conducted. Moisture contents are verified with a microwave oven. Mass differences between moist and dry specimens are
calculated (as specified in ASTM D4643). Moisture data also are collected using the NDG and speedy moisture tester (ASTM D4944); however, these data are not used for moisture
adjustment.
Collecting data from the initial 8-in. soil layer helped investigators familiarize themselves with the various equipment used during this study. These data, however, were not used in the final statistical analysis. A summary of data collected during the first two test series is presented in Table 3.1.
Table 3.1: Data generated during first two test series - Phase I
Test Date Test Types Additional Comments
01-25-2013 NDG, wet density, percent moisture, dry density (typical), GeoGauge, DSPA, LWD-P, LWD-1, BCD, speedy moisture tester
Tests only on lower 8-in.
compacted lift
01-28-2013 NDG Tests on upper 8-in.
compacted lift
Figure 3.10: Testing device orientation in the test box
3.3.2 Test Box Preparation for Third Test Series
Test box preparation for the third test series is similar to procedures outlined previously. Soil is mixed, brought to optimum water content, and added to the test box in 8-in. (compacted)
increments. However, tests are conducted on the entire 16-in. depth (as opposed to one test series per lift). Between tests, the test box is covered with 6-mil (0.006-in.) Visqueen to
minimize moisture loss due to evaporation. A summary of information associated with this test series is presented in Table 3.2.
Table 3.2: Data generated during third test series - Phase I
Test Date Test Types Additional Comments
01-30-2013 NDG Tests indicated that moisture
had dropped below optimum (indicating draining)
01-31-2013 GeoGauge, DSPA, LWD-1, LWD-P, BCD, DCP
LWD-P malfunctioned 02-01-2013 LWD-P, mini-PLT, speedy moisture tester LWD-P would not
communicate with PDA; mini-PLT malfunctioned
02-04-2013 Percent moisture at upper lift, 8 in. below surface, bottom 8 in.
Data showed significantly higher water contents in the bottom of the test box (indicating draining)
02-06-2013 LWD-1, LWD-2, LWD-P LWD-P continued to
malfunction
These data appeared to indicate that water was draining from the top of the test box over time.
As a result, a modified procedure was needed to ensure consistent moisture content during a test series.
3.3.3 Test Box Preparation for Subsequent Test Series
Because of the variability in moisture content, a new preparation procedure was developed.
One-half of the test box soil (as determined by its mass) is removed from the box. This soil is transferred to the mixer, mixed for ten minutes, and brought to optimum moisture content.
Meanwhile, the remaining soil is moved from the test box to a temporary storage unit. Once soil in the mixer is at optimum moisture, it is transferred from the mixer to the test box. This soil is compacted to an 8-in. lift and planed. The soil in the temporary storage unit is added to the mixer, mixed with water, and brought to its optimum moisture content. Once at optimum moisture, it is added to the test box, compacted to another 8-in. lift, and leveled. Test series are conducted on the full 16-in. soil depth and compared with NDG tests. A summary is presented in Table 3.3.
Table 3.3: Data generated during subsequent test series - Phase I
Test Date Test Types Additional Comments
02-08-2013 NDG, GeoGauge, BCD, DSPA, LWD-1, LWD-2, DCP, mini-PLT, speedy moisture tester
02-12-2013 Speedy moisture tester Box was allowed to sit idle for four days; moisture tested at various depths; results appeared to indicate some draining had occurred 02-15-2013 NDG, GeoGauge, BCD, DSPA, LWD-1, DCP,
mini-PLT, speedy moisture tester
Box was prepared on 02-14-2013 and covered with Visqueen
02-26-2013 NDG, GeoGauge, LWD-1, BCD, DSPA, DCP, NDG, mini-PLT, speedy moisture tester, wet density, dry density
Box was prepared on 02-25-2013 and covered with Visqueen
03-01-2013 NDG, GeoGauge, BCD, DSPA, DCP, mini-PLT, speedy moisture tester
Box was prepared on 02-28-2013 and covered with Visqueen
03-07-2013 NDG, GeoGauge, BCD, DSPA, LWD-1, DCP, Mini-PLT
03-08-2013 NDG, percent moisture, speedy moisture tester Tests were conducted using box prepared from previous day
3.4 Compactive Effort and Moisture Determination Required soil volume per lift is computed per Eq. 3.1:
box* soil reqd
V W (Eq. 3.1)
where Vbox is the volume per lift;
soil is the density of the soil at optimum moisture; and Wreqd is the weight of soil required. Based on the box surface area (35.4 in. by 35.5 in. = 1256.7 in.2), an 8-in. lift, and an optimum density of 112 lbs. per cubic ft., approximately 5.818 cubic ft. of soil is required per lift.Throughout mixing, moisture is determined by microwave oven. The amount of water needed for the optimum moisture content is then determined and adjusted. Research pertaining to moisture probes has been limited to a review of the literature including manufacturers’ data. An
easy-to-use, cost-effective moisture probe producing results to the desired accuracy was not identified.
3.5 Phase I Test Pit Equipment Evaluations