SCEBs - University of Colorado Boulder

indicate that no significant strength benefits are achieved by the continued addition of
sand to the mix. In fact, the average UCS for the 1:4 soil mixes was slightly less than the
average UCS for the 1:3.5 soil mixes. The author suggests that based on the observed
trend, a clay to sand soil mix ratio ranging from 1:3 to 1:4 is optimal for further
investigation with large block testing.
Special care was taken to prepare the specimens at the same water content to
minimize the number of factors affecting the results. Soil samples taken from each mix,
at the time of production, indicated a water content range of 11-12%. All specimens
were produced with the same applied pressure and cured for the same amount of time.
Figure 4.25: UMU Mini-Blocks; Varied Soil Mix Ratios
Soil Mix
Ratio
UMU Soil #11 Mix Ratio Test Results
Average Dry
Density [pcf]
Average UCS
[psi]
Average E
[ksi]
1:2.5 136.5 1,346.7 37.4
1:3 136.2 1,741.7 42.7
1:3.5 132.3 1,887.0 43.0
1:4 132.3 1,870.9 42.2
Table 4.15
54