Figure 3.8: Block Diagram Of Soil At Shrinkage Limit

Figure 3.8: Block Diagram of Soil at Shrinkage Limit

3.13.2 TABULATION AND RESULTS

Data and observation sheet for Consistency Limits determination:
Shrinkage Limit

Performed for __________________ Location __________________________ Project ________________________ Job No. ___________________________ Boring No. ______________ Sample No. _____________ Depth _________ Description of soil __________________________________________________________ Performed by __________________________ Date of Test ________________________
S.N Determination No. 1 2 3
1
2
3
4
5
6
7
8

9
10 Wt. of container in gm,W1
Wt. of container + wet soil pat in gm,W2
Wt. of container + dry soil pat in gm,W3
Wt. of oven dry soil pat, W0 in
The grain size distribution is widely used in the classification of soils, in the design of filters for earth dams and to determine suitability of soil for the construction of roads, airports, etc. Information obtained from grain size analysis can also be used to predict in a general way how a soil is expected to behave with respect to shear strength, settlement and permeability.
4.1.4 Principle of grain size determination
Soil consists of an assembly of soil particles (discrete particles) of various shapes and sizes. The object of a particle size analysis is to group these particles into separate ranges of sizes and so determine the relative proportion by weight of each size range. The method employs sieving and sedimentation of a soil/water/dispersant suspension to separate the particles. Different procedures are required for fine and coarse-grained materials. Detailed procedures are described in the ASTM D422 and BS Standards, Methods of testing soil for engineering
Uniformity Coefficients of less than 4 usually indicate uniform soils while well graded soils have uniformity coefficients equal to or greater than 4. Cu > 5 is an indication of gravels and Cu > 6 is for sands.
© Coefficient of Gradation or Coefficient of Curvature Cg: This is a measure of the shape of the particle size curve.
Cg = (D30)2/ D60 x D10 4.6
Cg from 1 to 3 ------- connotes a well graded soil 4.7

Special cases of poorly graded soils are gap-graded (curve E) and uniformly graded soils (curve C). Gap-graded soils can occur either as a result of two separate soils being mixed together or as a result of removing some range of intermediate particle sizes. Uniformly graded soils consist almost entirely of particles having the same size. A well-graded soil has coefficient of curvature which lies between 1 and 3. If a soil fails one or both the Cu and Cg criteria, it is considered to be poorly