OBJECT: To determine the Sand Equivalent Value of sand.
STANDARDS:
AASHTO T 176
ASTM D 2419:
OBJECTIVE:
- The sand equivalent test is a rapid field test to show the relative proportions of fine dust or clay-like materials in fine aggregate (or granular soils).
- Excessive dust or plastic fines (clay-like fine particles) in HMA aggregate can contribute to a lack of stability (rutting or shoving) or moisture damage and stripping. A simple test to determine whether or not a particular aggregate has enough dust or plastic fines to make an HMA mixture unstable or susceptible to stripping is valuable in preventing the manufacture of poor-performing mixtures
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THEORY:
A small sample of fine aggregate passing the No. 4 (4.75 mm) sieve is placed in a graduated cylinder and mixed with a flocculent solution to separate fine dust of clay-like particles from the rest of the aggregate sample. The sample is shaken and then allowed to sit for 20 minutes. The height to the top of the sand particles is expressed as a percentage of the height to the top of the fine/clay-like particles. Figure 3 shows the major sand equivalent test equipment
Test Procedure
In the sand equivalent test, a sample of aggregate passing the No. 4 (4.75 mm) sieve is taken. Then a small amount of flocculating solution is poured into a graduated cylinder.
Cylinder is agitated to loosen the clay-like coatings from the sand particles.
The sample is then irrigated with an additional flocculation solution forcing the clay-like material into suspension above the sand.
After a prescribed sedimentation period, the height of flocculated clay and the height of sand are determined.
The sand equivalent is expressed as a ratio of the height of sand over the height of clay.
Higher sand equivalent values indicate “cleaner” (less fine dust or clay-like materials) aggregate
OBSERVATION:
Calculations:
SE=x 100
RESULT:
Review Questions:
- What is the object of the sand equivalent test?
- The formula to calculate sand equivalent is.
- The sample of soil must be passed through.
