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Earthworks Module #7 Prepared by Dr. Randy R. Rapp July 2005.

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Presentation on theme: "Earthworks Module #7 Prepared by Dr. Randy R. Rapp July 2005."— Presentation transcript:

1 Earthworks Module #7 Prepared by Dr. Randy R. Rapp July 2005

2 2005, Randy R. Rapp2 Soil Classification Texture, consistency, mineralogy, and structure Unified Soil Classification System (USCS) American Assn. of State Highway and Transportation Officials (AASHTO)

3 2005, Randy R. Rapp3 USCS Coarse-grained vs. fine-grained Coarse: –Gravels –Sands –Sieve analysis size distribution: well and poorly graded Fine: –Silts –Clays: kaolinite, illite, montmorillonite or smectite –Mineralogy and geological history matters: Atterberg liquid and plastic limits (LL or w l ; PL or w p ) Chart, pp. 152-53

4 2005, Randy R. Rapp4 Compaction Standard or Modified Proctor test: optimum moisture content (OMC) to achieve γ dry,max (lb/ft 3, pcf) for compactive effort Specifications usually % range of γ dry,max and ± 1.5 to 2% of OMC Proctor suffices for most soils, but relative density might be applied for coarse soils

5 2005, Randy R. Rapp5 Compaction Molds and Hammers Standard Proctor –Mold, 4-in I.D. 0.333-ft 3 or 944-cm 3 –Hammer blow 5.5-lb dropped 12-in Modified Proctor –Mold, 6-in I.D. 0.0752-ft 3 2,130-cm 3 –Hammer blow 10-lb dropped 18-in

6 2005, Randy R. Rapp6 Field Compaction Roller types Behavior of rollers during multiple passes Relating Proctor to field density: test strips Field density testing: –Random, at least every few thousand yd 3 –Nuclear density gauge (or meter) –Sand cone density test to check the nuke

7 2005, Randy R. Rapp7 Inspection Control Observation of passes Borrow pit concerns (p. 163) Embankment (pp. 163-64) Determining average depth of lift Payment

8 2005, Randy R. Rapp8 Stabilizing Additives Additives –Portland cement –Lime (hydrated and quick) –Bituminous materials Curing requirements are critical

9 2005, Randy R. Rapp9 OSHA Competent person –Knowledge –Authority Expedient soil classification (pp. 167-69; 174-76) Rock and Soil Types, for trench shoring –A, ¾:1 –B, 1:1 –C, 1-½ : 1

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