Soil Mechanics ch.3

Which type of Proctor uses a 10-lb hammer and an 18-in. drop?

• The original Proctor proposed by R.R. Proctor

• .The modified Proctor (ASTM D1557)

• The standard Proctor (ASTM D698)

In ASTM D1557 method A, what size screen is the material sieved through?

• #200

• #40

• .#4

Optimum moisture is the point that:

• A sandy soil should be screened across the #4 sieve

• A fine-grained soil becomes liquid

• .Soil will compact best in both the field and laboratory

• No more water can be retained in a soil

A 40% solution of sodium hexametaphosphate is used to:

• Remove dry soil from dirty sieves

• Break down adhesion of noncohesive soils

• .Soften and break down the adhesion of cohesive soils

• None of the above

The hydrometer analysis is used to determine the particle-size distribution of:

• Sand, clay, and silt

• Sand and colloids

• .Material finer than the #20 sieve

• None of the above

Hydrometer readings should always be taken at the top of the meniscus.

• .True

• False

A sample that cannot be rolled smaller than 1/8 in. without crumbling is to be considered:

• CL/ML (per the liquid limit and plasticity graph)

• Medium plastic

• .Nonplastic

• To have a high liquid limit

PI = LL – PL.

• .True

• False