The main difference in the two tests are that the standard Proctor test uses a 5.5-lb hammer dropping a distance of 12 in, whereas the modified Proctor uses a 10-lb hammer dropping 18 in . The difference is to simulate either light rollers or tamping for the standard Proctor, and heavy rollers for the modified Proctor.
What is Modified Proctor test?
A Modified Proctor test is conducted by placing soil in a standard mold and compacted with a standard ram . Modified Proctor Test Procedure: ... Typically, soil is placed in five layers and compacted. STEP 3: After compaction of all five layers, the weight of the soil is obtained. The soil contains solids and water.
What is the difference between modified and standard compaction tests?
The test is similar to standard compaction, but a modified compactive effort is imparted to remould the specimen instead. Thus, the only difference is with regards to the amount of energy used to compact the material .
What are the main characteristics of standard Proctor test and modified Proctor test which test is preferable and why?
Modified Proctor Test is best suited for structures with high dynamic and static loadings like skyscrapers and runways , on the other hand, Standard Proctor Test is suitable for the soil with nonheavy loadings. OMC (Optimum Moisture Content) obtained in Standard Proctor Test is higher compared to Modified Proctor Test.
Why was standard Proctor test modified?
What Is Modified Proctor? Modified Proctor Test is used to determine the compaction of different types of soil and the properties of soil with a change in moisture content ; and the relationship between Dry Density and Moisture Content.
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 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.
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 Proctor test is done?
The Proctor compaction test is a laboratory method of experimentally determining the optimal moisture content at which a given soil type will become most dense and achieve its maximum dry density . ... The graphical relationship of the dry density to moisture content is then plotted to establish the compaction curve.
Which equipment is used in Proctor test?
Standard Proctor Test Apparatus:
Cylindrical Metal Mold , having internal diameter 4” (10.16 cm) or 6” (15.24 cm), the internal effective height of 4.6” (11.7 cm); and the mold should have detachable base plate & collar of 2 inches (5.08 cm).
What is CBR value?
CBR is the ratio expressed in percentage of force per unit area required to penetrate a soil mass with a standard circular plunger of 50 mm diameter at the rate of 1.25 mm/min to that required for corresponding penetration in a standard material. The ratio is usually determined for penetration of 2.5 and 5 mm .
How do you perform a Proctor test?
- Obtain about 3 kg of soil.
- Pass the soil through the No. ...
- Weight the soil mass and the mold without the collar (W m ).
- Place the soil in the mixer and gradually add water to reach the desired moisture content (w).
- Apply lubricant to the collar.
Is code for MDD of soil?
Determination of Maximum Dry Density and Optimum Moisture Content of Soil – IS:2720 (Part VII) The determination of maximum dry density and optimum moisture content of the soil is a measure of compaction level of soils.
Why is the maximum density higher in the Modified Proctor test compared to the standard Proctor test?
∗ The density difference between Modified Proctor and Standard Proctor density testing appears to increase with the percentage of fines in the soil matrix while the optimum moisture content decreases .
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.
Can you over compacted soil?
Don't overdo it
Like many things, soil compaction is an area where you can get too much of a good thing. Soil can become over compacted, which threatens to undermine its bearing capacity. “Continued compaction can cause soil to break down and cause segregation in soil mixes,” says Fabian Salinas at Dynapac.
