For example, specifications often require compaction to be 95 percent of Standard Proctor. This means the on-site soil density must be equal to 95% of the maximum achievable compaction . • Compaction is achieved by applying three basic types of force to the soil mass.
What is compaction percentage?
[pər′sent kəm′pak·shən] (engineering) The ratio, expressed as a percentage, of dry unit weight of a soil to maximum unit weight obtained in a laboratory compaction test.
What does it mean to have 95% compaction?
95% compaction means that the soil on the construction site has been compacted to 95 % of the maximum density achieved in the lab . ... It means that when you conduct compaction test(in the laboratory) on a small soil sample of a particular site. You get some value of maximum dry unit weight at certain moisture content.
Can relative compaction exceed 100%?
This can range from 90 percent to over 100 percent . Modified compaction tests have also been introduced in connection with structures requiring heavier bearing strength to support extremely heavy loads or to limit settlement.
How do you calculate compaction percentage?
Compaction Percentage calculates by dividing the dry density by maximum dry density .
Can compaction be more than 100?
In case the compaction test results indicate values exceeding 100%, it only means that the in-situ compaction is more than that being carried out in laboratories which is treated as the basic criterion for satisfactory degree of soil compaction.
What is Mmdd compaction?
In a standard compaction test, each sample is compacted in three layers, each by 25 blows of 2.5 kg rammer falling 300 mm on the soil. The maximum dry density obtained by this testing method is referred to as SMDD. ... The maximum dry density obtained by this testing method is referred to as MMDD.
How is compaction test calculated?
3.7 Calculate percent relative compaction by dividing the dry density of the material from the test site by that material’s moisture density relation curve’s maximum dry density, and multiply by 100% .
What is OMC and MDD?
MDD – Maximum Dry Density . MWD – Maximum Wet Density. OMC – Optimum moisture Content. ... Zero Air Voids – is the relationship between dry density and corresponding moisture contents, for a specific particle density, assuming that all of the voids are completely filled with water.
Why compaction is required?
Why is Soil Compaction Important? Soil compaction is necessary to increase the bearing capacity and stiffness of in-situ (natural state) or chemically modified soils. Compaction increases the shear strength of soils by adding friction from the interlocking of particles.
How does compaction work?
What is compaction? Soil compaction occurs when soil particles are pressed together, reducing pore space between them (Figure 1). Heavily compacted soils contain few large pores, less total pore volume and, consequently, a greater density. A compacted soil has a reduced rate of both water infiltration and drainage.
How do you test for sand compaction?
- (1) Cutting ring and Sand replacement methods are most commonly used in testing compaction degree of the subgrade. ...
- (2) PFWD is used to test the resilient of the subgrade, and easy to operate. ...
- (3) Bearing plate is used to test the static resilient modulus of the subgrade.
Can soil be over compacted?
Soil can become over compacted , which threatens to undermine its bearing capacity.
What is ASTM D6938?
ASTM D6938
This test method describes the procedures for measuring in-place density and moisture of soil and soil-aggregate by use of nuclear equipment . The density of the material may be measured by direct transmission, backscatter, or backscatter/air-gap ratio methods.
How is FDT calculated?
Calculation For FDT Test:
The volume of the hole = Mass of sand in hole/Density of used sand. Degree of compaction = Dry density × 100%/Maximum dry density.
How is 95 compaction calculated?
The level of compaction in a soil mass is determined by comparing the density of the soil as measured at the site with the density of that soil type as defined in the Standard Proctor tests. ... This means the on-site soil density must be equal to 95% of the maximum achievable compaction.
