Alexandria University

Second Year Civil

Faculty of Engineering

Soil mechanics and foundations

Structural Engineering Dept.

First Term 2015/ 2016 SHEET# 4

SOIL COMPACTION Problem (1) The following data were recorded during a sand cone test:  Weight of soil removed from hole is 2.30kg  Weight of soil after drying is 2.08kg  Initial total weight of sand pouring cylinder is 4.40 kg  Weight of sand pouring cylinder after running sand into the hole is 2.25 kg  Unit weight of pouring sand is 1.68 gm/cm3  Weight of sand in cone sand cylinder is 0.35 kg Determine the bulk and dry unit weight of the soil in-situ. Problem (2) The following data were recorded during a compaction test: Wc (%) Soil wt. (Kg)

4 1.94

6 1.98

8 2.05

10 2.12

12 2.08

Volume of mold = 0.00095 m3, Gs = 2.70 It is required to: a) Plot the curve of dry density against moisture content, and from it, obtain the maximum dry density and optimum moisture content of the compacted soil. b) On the same axis, plot the dry density against moisture content for zero percent air voids. c) Obtain the air voids of the soil at the optimum moisture content. Problem (3) Soil has been compacted in an embankment at a bulk unit weight of 2.15 t/m3, and water content of 12.5 %. The specific gravity of solids is 2.7. Calculate the dry unit weight, degree of saturation and air content. Would it be possible to compact the above soil at water content of 14 % to a dry unit weight to be 2.25 t/m3.

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