3 Compaction Problem Set SOLN

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University of Alberta *

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Apr 3, 2024

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CIV E 381 Fall 2022 Topic 2: Compaction 1 | P a g e Question 1. A series of Standard Proctor compaction tests have been performed on a soil sample. The test results are presented in Table 1. Table 1. Results from Standard Proctor compaction tests. Data point number 1 2 3 4 5 Mass of compacted soil+mold (kg) 3.672 3.921 4.034 4.091 4.04 Mass of can (g) 20.11 21.24 19.81 20.3 20.99 Mass of can +wet soil (g) 240.85 227.03 263.45 267.01 240.29 Mass of can +dry soil (g) 231.32 212.65 241.14 238.81 209.33 The mass of the compaction mold was 2.031 kg. The moisture content tests were performed on small portions of the compacted soil samples. a) Compute dry density ( 𝜌 ? ) and water content ( ω ) for each data point and plot these results. b) Develop and plot curves for 𝑆 = 80% and 𝑆 = 100% using a specific gravity ( G s ) of 2.69 on the sample plot as part a. c) Using the data from parts a and b, draw the Proctor compaction curve and determine 𝜌 ?(???) and 𝑤 ???𝑖??? . (Reference: Assignment2, 2018) Solution : a) Compute dry density ( 𝜌 ? ) and water content ( ω ) for each data point and plot these results. Table 1. Results from Standard Proctor compaction tests. Data point number 1 2 3 4 5 Mass of compacted soil+mold (kg) 3.672 3.921 4.034 4.091 4.04 Mass of can (g) 20.11 21.24 19.81 20.3 20.99 Mass of can +wet soil (g) 240.85 227.03 263.45 267.01 240.29 Mass of can +dry soil (g) 231.32 212.65 241.14 238.81 209.33 Bulk density ( 𝝆 ) ( 𝒌?/𝒎 ? ) 17.38 20.02 21.22 21.82 21.28 Water content ( 𝒘 ) (%) 4.51 7.51 10.08 12.91 16.44 Dry density ( 𝝆 ? ) ( 𝒌?/𝒎 ? ) 16.63 18.62 19.28 19.33 18.28
CIV E 381 Fall 2022 Topic 2: Compaction 2 | P a g e b) Develop and plot curves for S = 80% and S =100% using a specific gravity ( G s ) of 2.69 on the sample plot as part a. Hint: Estimate the water content for the ranges of dry density values using the equation: 𝑤 = ( 𝐺 ? 𝜌 ? 𝜌 ? − 1) 𝑆 𝐺 ? Accordingly, the calculated values of water contents ( 𝑤 ) for S = 80% and S = 100% are tabulated in the table below: Dry density ( 𝝆 ? ) ( 𝒌?/𝒎 ? ) 16.33 18.28 18.92 18.97 17.94 𝒘 (%) at 𝑺 = ??% 18.36 13.22 11.76 11.65 14.03 𝒘 (%) at 𝑺 = ???% 22.95 16.52 14.71 14.56 17.54 c) Using the data from parts a and b, draw the Proctor compaction curve and determine 𝜌 ?(???) and 𝑤 ???𝑖??? . 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 0 2 4 6 8 10 12 14 16 18 Dry Density (kN/m3) Water Content (%) Standard Proctor Curve
CIV E 381 Fall 2022 Topic 2: Compaction 3 | P a g e From the proctor curve: The maximum dry density ( 𝜌 ?(???) ) = 19.4 𝑘?/𝑚 3 The optimum moisture content ( 𝑤 ???𝑖??? ) = 11.8% Question 2. You are the QA/QC engineer on a road construction project tasked with measuring the field dry density and field moisture content of recently compacted road base. Please explain the following scenarios. a) Using a nuclear densometer, you have determined the field dry density is above the laboratory determined compaction curve (lab dry density vs moisture content). Explain what may contribute to this difference? b) Using the nuclear densometer, you have determined the field dry density is below the Relative Compaction specification and the field moisture content is greater than the acceptable range of moisture contents. What might you recommend as a corrective action to the contractor in order to meet the specifications? 16.00 16.50 17.00 17.50 18.00 18.50 19.00 19.50 20.00 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 Dry Density (kN/m3) Water Content (%) Proctor Curve S = 80% S = 100%
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