What is CC and Cu in sieve analysis? The uniformity coefficient (Cu) and the coefficient of gradation (Cc) are the measures of soil gradation. These coefficients help to classify the soil as well graded or poorly graded ones.
What is the use of Cu and CC?
Cc = (D30)^2 / (D60) (D10). What is the use of this Cu and Cc? Cu is always greater than 1 (equal to 1 is possible only by theoretical). If Cu is closer to 1 ( ie. D60 and D10 sizes are close to each other, which means there are more no. of particles are in the same size range ), the soil is considered as uniformly graded.
What is Cu and CC in soil mechanics?
The uniformity coefficient (Cu) and the coefficient of gradation (Cc) are the measures of soil gradation. These coefficients help to classify the soil as well graded or poorly graded ones. Click to see full answer.
How are the results of sieve analysis expressed?
Figure 1. Set of sieves in a sieve shaker The results of sieve analysis are generally expressed in terms of the percentage of the total weight of soil that passed through different sieves. Table 2 shows an example of the calculations required in a sieve analysis. Table 2.
How do you find the CU and CC of a particle?
For example, if you have 100 particles of diameter ranging from 1 mm to 100 mm, D60 is 61 mm (below which 60% of particles are there). Why do we find this? To find Cu and Cc. Cu – Uniformity coefficient. Cu = D60/D10. Cc – Coefficient of curvature. Cc = (D30)^2 / (D60) (D10). What is the use of this Cu and Cc?
What is CC in sieve analysis?
Coefficient of Cuvature (Cc) is a value that can be used to identify a poorly graded soil. 60.
What is coefficient of curvature CC?
The coefficient of curvature is a measure of gradation of particles and given by the following expression: Cc = (D30)2/D60.D10. Where, D60 = Size of the particle corresponding to 60% finer.
What is meant by coefficient of uniformity?
uniformity coefficient (u-ni-form'-i-ty). A numerical expression of the variety in particle sizes in mixed natural soils, defined as the ratio of the sieve size through which 60% (by weight) of the material passes to the sieve size that allows 10% of the material to pass.
What is uniformity coefficient of sand?
Uniformity Coefficient (UC) – This is defined as a ratio and is calculated as the size opening that will just pass 60% of the sand (d60 value) divided by the size opening that will just pass 10% of the sand sample (d10 value). ES is basically a value describing the average size of sand grains in a sand sample.
What is D10 in sieve analysis?
The effective size of a given sample of sand is the particle size where 10% of the particles in that sample (by weight) are smaller, while 90% are larger. Usually this is denoted as the D10.
What is the difference between coefficient of uniformity and coefficient of curvature?
The coefficient of uniformity or the CU is the ratio of the D60 by D10, if the ratio is greater than 4, then the soil is considered as good quality soil. But if the ratio is less than 4 then the soil is considered as bad quality soil. On the other hand, the coefficient of curvature is the ratio of (D30)2/(D10.
What is D10 particle size distribution?
For example D10 is defined as the point on the distribution curve below which 10% of the particles fall (denoted by the green filled area labeled 10% in Figure 1). For this distribution, the D10 is 9.0 microns.
What is the shrinkage limit?
Shrinkage Limit Set The shrinkage limit of cohesive soils is defined as the water content at which further loss of moisture will not cause a decrease in volume.
What is D60 and D10?
Particle size distributions of samples (D10, D30, and D60 are the particle sizes corresponding to 10%, 30%, and 60% finer materials on the cumulative particle size distribution curve, respectively).
Why is D10 effective size?
Because it gives the maximum particle diameter of the smallest 10% of soil particles. D10 is termed as the effective particle size it means that 10 percent of the particles are finer and 90 percent of the particles are coarser than that particular particle size D10.
What is the value of Cu in soil?
A value of Cu greater than 4 to 6 classifies the soil as well graded. When Cu is less than 4, it is classified as poorly graded or uniformly graded soil. Uniformly graded soil has identical particles with Cu value approximately equal to 1. A uniformity coefficient value of 2 or 3 classifies the soil as poorly graded.
What does higher Cu mean?
Higher value of Cu indicates that the soil mass consists of soil particles with different size ranges.
What is the uniformity coefficient?
The uniformity coefficient (Cu) and the coefficient of gradation (Cc) are the measures of soil gradation. These coefficients help to classify the soil as well graded or poorly graded ones.
What does a higher Cu mean in soil?
Beach sand comes under this category. A higher value of Cu indicates that the soil mass consists of soil particles with different size ranges.
What is the value of Cc in soil?
For the soil to be well graded, the value of Cc must range between 1 and 3.
What is the uniformity coefficient?
The uniformity coefficient (Cu) and the coefficient of gradation (Cc) are the measures of soil gradation. These coefficients help to classify the soil as well as graded or poorly graded ones.
What is the IS code for sieve analysis?
The sieve analysis test has been carried out either by the mechanical, manual, or electrical method as per IS code 2386 Part 1.
Why is sieve analysis important?
Sieve Analysis test helps. To determine the quality of aggregates based on the size.
What is the test used to determine the particle size of fine and coarse aggregates?
A test used to determine the particle size of fine and coarse aggregates is known as the sieve analysis test .
How long to sieve a sample?
Now fill the sample to the highest sieve and sieve well for up to 10 minutes.
What is coarse aggregate?
The aggregates are graded as fine and coarse aggregate based on the grain size. When the aggregate size is greater than 4.75mm is called coarse aggregate, and less than 4.75mm is called fine aggregate.
What is the grain distribution curve?
For a uniformly graded soil, the grain distribution curve is almost vertical. For a well graded soil, the curve has a good slope. For a gap graded soil, the curve is almost horizontal in between any two points.
Is Cu graded sand or gravel?
If Cu is away from 1, the soil is well graded(ie. it has a vareity of size range distributed well). For gravel, if Cu>4, it is well graded. For sand, if Cu>6, it is well graded.
Is Cu greater than 1?
Cu is always greater than 1 (equal to 1 is possible only by theoretical). If Cu is closer to 1 ( ie. D60 and D10 sizes are close to each other, which means there are more no. of particles are in the same size range), the soil is considered as uniformly graded.
What is Sieve analysis?
Sieve analysis is the method of particle size analysis, using which we determine the amount of particles of different sizes present in the soil sample.
How to find the percent weight retained on the 1st sieve?
Percentage weight retained on the 1st sieves is w 1 divided by W multiply by 100.
How to calculate percentage of soil retained on each sieve?
Then we calculate the percentage of amount of soil retained on each sieve as weight of retained soil on the sieve divided by total weight of soil sample multiplied by 100.
What is a 600 micron sieve?
A sieve with a mesh opening of 4.75 mm is designated as 4.75 mm Sieve (Sieve number written on sieve). Similarly a 600 micron sieve refers to a sieve which has a mesh opening of 0.600 mm.
What size sieves are needed for gravel?
For gravel fractions we require sieves of sizes 80 mm, 40 mm, 20 mm, 10 mm and 4.75 mm. This set is called set of coarse sieves as it sieves coarser part of the coarse soils.
What is cumulative percentage retained?
Cumulative percentage retained is the total percentage amount of soil which could not pass the particular sieve.
What is the finest sieve?
The finest sieve used in the analysis is 75µ. If the portion passing through 75µ sieve, which we collect in the pan, is substantial, say 5 to 10%, then wet sieve analysis is carried out.
Is Cu greater than 1?
Cu is always greater than 1 (equal to 1 is possible only by theoretical). If Cu is closer to 1 ( ie. D60 and D10 sizes are close to each other, which means there are more no. of particles are in the same size range ), the soil is considered as uniformly graded.
Is Cu graded sand or gravel?
If Cu is away from 1, the soil is well graded (ie. it has a vareity of size range distributed well ). For gravel, if Cu>4, it is well graded. For sand, if Cu>6, it is well graded.
What are the coefficients of uniformity in poor graded soil?
Poorly graded soils have uniformity coefficients < 4 and steep gradation curves. Well-graded soils have uniformity coefficients > 4, coefficients of curvature between 1 and 3, and flat gradation curves. Gap-graded soils have coefficients of curvature < 1 or > 3, and one or more humps on the gradation curves.
How to determine grain size distribution of coarse-grained soil?
Sieve analysis is used to determine the grain size distribution of coarse-grained soils. For the particle size distribution of fine-grained soils, a hydrometer analysis is used. Particle size distribution is represented on a semi logarithmic plot of % finer (ordinate, arithmetic scale) versus particle size (abscissa, logarithm scale). The particle size distribution plot is used to delineate the different soil textures (percentages of gravel, sand, silt, and clay) in a soil. The effective size, D 10, is the diameter of the particles of which 10% of the soil is finer. D 10 is an important value in regulating flow through soils and can significantly influence the mechanical behavior of soils.
How is a soil sample shaken?
A sample of dry soil is poured onto the top sieve, the nest is covered, and it is then shaken by hand or mechanical sieve shaker until each particle has dropped to a sieve with openings too small to pass, and the particle is retained. The cumulative weight of all material larger than each sieve size is determined and divided by ...
What is sieve analysis?
Sieve analysis consists of shaking the soil sample through a set of sieves that have progressively smaller openings. Table 1 lists the U.S. standard sieve numbers and the sizes of openings.
What is the difference between Cu and D60?
where Cu is the uniformity coefficient and D60 is the diameter corresponding to 60% finer in the particle-size distribution
How to determine cohesive soil?
Figure 1 shows a set of sieves in a sieve shaker used for conducting the test in the laboratory. After the completion of the shaking period the mass of soil retained on each sieve is determined. When cohesive soils are analyzed, it my be difficult to break lumps into individual particles. In that case, the soil may be mixed with water to make a slurry and then washed through the sieves. Portions retained on each sieve are collected separately and oven dried before the mass retained on each sieve is measured.
How long to hand sieve soil?
At least 10 minutes of hand sieving is desirable for soils with small particles. Weigh to 0.1 g each sieve and the pan with the soil retained on them. Subtract the weights obtained in step 1 from those of step 5 to give the weight of soil retained on each sieve.
How to recover soil from a 200 sieve?
200 sieve, it should be washed. This is done by placing the sieve and retained soil in a pan and pouring clean water on the screen. Use a spoon or glass rod to stir the slurry. Recover the soil which is washed through; dry and weigh it. The weight of soil recovered should be subtracted from the weight retained on the No. 200 sieve and added to the weight retained in the pan as determined in step 6.
Why weigh soil on sieve?
The method of weighing the sieve plus soil rather then attempting to remove the soil from the sieve for weighing is suggested because it has been found that soil is often lost during the removing. Even using this suggested procedure, be careful to minimize the lose of soil during the sieving.
What are particle size distribution curves used for?
The particle-size distribution curves can be used for comparing different soils. Also, three basic soil parameters can be determined from these curves, and they can be used to classify granular soils. Them parameters are: