Question

Your boss needs to recommend either the in-situ soil or the borrow material. Although you do not have much background on soil behavior, what is your recommendation?
In providing your recommendation, you want to consider constructability issues (such as ease of compaction, moisture content). Without doing any additional tests, and based on your experience with soils, what compaction conditions would you suggest to achieve low permeability? What compaction conditions would you recommend to reduce soil expansion (swelling)?

Table 1 Compaction Characteristics of Selected Soils.
Borrow Soil In-Situ Soil
STANDARD MODIFIED STANDARD MODIFIED
PROCTOR PROCTOR PROCTOR PROCTOR
Dry Unit Water Dry Unit Water Dry Unit Water Dry Unit Water
Weight Content Weight Content | Weight Content Weight content
Yd (kN/m³) w(%) Yd (kN/m³) w(%) Yd (kN/m³) w(%) Yd (kN/m³) w(%)
16.68 8.4 17.58 5.7 15.63 12.7 15.72 10.4
18.79 9.7 20.02 7.4 17.72 14.4 18.76 12.2
S3? S3? 20.60 9.3 17.46 16.0 18.64 14.0
18.62 13.4 19.62 11.3 17.15 16.7 18.15 15.0
18.05 15.0 18.93 13.0 16.30 18.2 17.48 16.4

Answer 1

Answer: see attached file for the answer