Soil Mechanics Final 100% accurate answers

Soil Mechanics Final 100% accurate answers What is the sieve number that is used to separate fine sand from medium sand? 40 What is the grain size diameter (in mm) that is the dividing line between fines and sand particles sizes? 0.075 TF: The diffuse double layer is the basic structure of each clay particle, and these clay particle diffuse double layers are the 2 different mineral sheets bonded together False. The diffuse double layer is the region of attracted positive ions in solution and the negatively charged surface of the clay The plastic limit test involves rolling out a soil thread until it just breaks into smaller pieces when thread is what diameter? 1/8 inch List the 4 conditions necessary for Liquefaction to occur in a natural sand deposit Loose soil, fine sand, below GWT, earthquakes TF: A clay soil is considered to be at its liquid limit when the slot closes for 1/2 inch of its length at 35 drops of the brass cup False. 25 drops TF: All the clay soils exhibit the same behavior and shear strength when at their Liquid Limit, even if one clay has LL=130% and another clay has LL=25% True List the three most common clay minerals that were discussed in class Montmorillonite, Kaolinite, Illite Which common clay mineral has the most potential for shrink and swell when water content changes? Montmorillonite What is the name of the lab test that is used to determine the grain size distribution of the particles of fine soil, that pass through the No. 200 sieve? Hydrometer Analysis TF: Clay soils usually have a void ratio that is greater than 1.0, but not sand. True Which of the following 4 USCS classified soils would be best for use as an impervious cap over a landfill, that must provide: impermeability, resistance to shrink-swell, and relative ease of compaction CL If a sand soil has a void ratio value of 0.30, then what term best describes its density? Very dense What is the symbol for porosity? n What is the symbol for void ratio? e What is the equation for the degree of saturation? s=(Vw/Vv)*100% What is the equation for the degree of water content? w=(Ww/Ws)*100% What is the equation for the specific gravity? s=(Ws/(Vs*Gammaw) A soil with 4% fines, and 51% passing the No. 4 sieve, with a Cu=5.2 and Cc=1.5 will be classified as which of the following? GW In the USCS system, write the three words that describe a soil classified as ML soil? Low plasticity silt TF: In working with a "performance" specification, only the required percent compaction is specified, but often the allowable range of moisture content is also specified True Make a sketch to the right of the soil fabric that results from compacting clay soil that is dry of optimum w.c. Particles are more spread out. Higher permeability and the particles stick together better ASTM test specification says that all the soil of a sample being tested in the lab Proctor test must pass through a No. 4 sieve if the 4-inch diameter compaction mold is to be used. If larger soil particles are present, what mold size must be used? 6 inch TF: To achieve good degree of compaction throughout the lift thickness of a clayey soil, the thickness of loose placed fill before compaction should not exceed about 8-10 inches True TF: The sheepsfoot roller is most often used to compact plastic clay soils because the small peg-like feet apply the high stresses needed to shear through the clay and manipulate the clay soils into denser condition True What should be the water content of clay soil being compacted for a landfill liner or as core of an earth-fill dam, both of which need to have very slow permeability? Wet of Optimum TF: The optimum moisture content of a clay soil is usually substantially lower than that for a well graded granular soil False. Clay is substantially higher than a well graded granular soil What are the details of the Modified Proctor compaction test that is done in a lab? Hammer weight, Hammer drop weight, number of soil layers, number of drops on each layer 10 lb, 18 in, 5, 25 TF: When clean, well graded sand and gravel soil is being compacted using a vibratory smooth-drum roller, the density test should be conducted at a depth of at least 5-inches below the compacted surface to avoid the loosening that occurs due to the intense vibrations the roller applies True What is the effect of increased compactive effort, on the same soil? That is, using the Modified Proctor test instead of the Standard Proctor Increased max dry unit weight and decreased optimum moisture content What is the best compaction equipment to use for a well-graded coarse to fine sand with very little silt? Smooth Steel Drum Vibratory Roller What is the best compaction equipment to use for low plasticity sandy clay soil with 25% silt? Self-propelled pad foot-type of sheepsfoot roller What is the best compaction equipment to use for non-plastic silty sand without any gravel? Pneumatic rubber-tired roller with water-filled ballast tank When the nuclear density test apparatus is used to determine density of compacted soil in the field, what are the two types of soils that it is most likely to experience greatest difficulties due to interfere with gamma ray and alpha ray transmissions? Gravelly glacial till and micaceous silty sand