Civil Engineering and Architecture Soil Classification Civil Engineering and Architecture Unit 4 – Site Planning

In this lesson: Discuss the types of materials generally labeled as soil Describe the characteristics of soil components

What is Soil? Gravel Clay Silt Sand

Testing the Soil Bearing Capacity Settling Characteristics Drainage

Site Planning Function of Structure Site Profile (Contour Map) Geological Information Soils Sample Data

Soil Samples Samples Represent the Site Taken about 1’-2’ below surface Boring samples are taken at various locations and depths below the surface (subsurface) for deep foundations.

Unified Soil Classification System Coarse-Grained Soils Fine Grained Soils Highly Organic Soils Professional Development Lesson ID Code: 8006

Unified Soil Classification System

Sieve Sizes Gravels range from 3” down to the size of peas. Silt and clay can pass through the #200 sieve.

Click here to open the Grain Size Chart.

Gravel Identification

Sand Identification

Graded Soil Well-Graded Soils-have a good representation of all particle sizes from the largest to smallest Poorly-Graded Soils- two types Uniformly-has soil particles nearly the same size. Gap-Graded- contains both large and small particles but the graduation continuity is broken by the absence of some particle sizes.

Clean vs. Dirty Graded Soil Clean: contains little or no fines (<5%) Dirty: contains an appreciable amount of fines ( >12%)

Clay or Silt? Dry Strength – crushing characteristics Dilatancy – reaction to shaking Toughness – consistency near plastic limit

Grain Shape

Soil Color * Can vary with moisture content * May indicate the presence of certain chemical or impurities * Dark brown /black may indicate organic material. * Gray, olive green indicate inorganic soils. * Gray-blue or gray-yellow indicates poor drainage. * Red or yellow may indicate iron oxides. * White to pink may indicate considerable silica, calcium carbonate, or aluminum compounds.

Plasticity Atterberg Limits: Plastic Limit-lowest moisture content at which soils can be rolled into 1/8” diameter thread without breaking. Liquid Limit- minimum moisture content at which soil will flow when a small shear or cutting force is applied.

Soil Groups Soil Type Gradation Liquid Limit Gravel- G Sand-S Silt-M Clay-C Organic O Peat- Pt Well Graded- W Poorly Graded - P LL over 50- H LL under 50 -L

Curriculum Alignment: Unit 4 – Site Planning Lesson 4.5 – Site Grading Act. 5.1 – Soil Testing

References: Dishongh, B.E. (2001). Essential Structural Technology for Construction and Architecture, Upper Saddle River, NJ: Prentice Hall Guthrie, P. (2003). Architects Portable Handbook: First Step Rules of Thumb for Building Design, New York, NY: McGraw-Hill Lindeburg, M.R. (1994). Civil Engineering Reference Manual, 9th ed. Belmont, CA: Professional Publications Inc

References: Sowers, G.F. (1979). Introductory Soil Mechanics and Foundations: Geotechnical Engineering, New York, NY: McMillian Publishing Unified Soil Classifications; http://www.hydro.unr.edu/homepages/bens on/classes/hydro/uscs.html. August 2004 US Army Unified Soil Classification System. http://www.adtdl.army.mil/cgibin/atdl.dll/fm/5 -472/apb.pdf. August 5, 2004

References: US Army Corps of Engineers. (1953). The Unified Soil Classification System, U.S. Army Technical Memorandum, No. 3-357.

Credits: Writer: Constance Bertucci Content Editor: Donna E. Scribner Narration: Donna E. Scribner PLTW Editor: Ed Hughes Production: CJ Amarosa Video Production: CJ Amarosa Audio: CJ Amarosa Project Manager: Donna E. Scribner