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

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)

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

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

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

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

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

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

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