index properties.pptx of soil in geo technical engineering

Index properties of soil

1. Index properties are two categories- Properties of individual particles . These properties can be determined from a remolded and disturbed sample. Properties of soil mass , also known as aggregate properties . A ggregate properties should be determined from undisturbed samples .

2. Water content Specific gravity In-situ density Particle size Consistency Relative Density

3. Pycnometer method Sand bath method Alcohol method Oven drying method Calcium carbide method Radiation method

4. G = ρ s / ρ w ρ s = Ms/Vs Vs = Ms/G ρ w

5. DETERMINATION OF MOISTURE CONTENT by Pycnometer method

6. This is a field method for the determination of water content . This method is rapid but not accurate . The container with the soil is placed on a sand bath . Heated over a kerosene stove. The soil become dry within ½ to hr.

7. Where, M1= mass of empty container M2= mass of container + wet soil M3= mass of container + dry soil M 3  M 1 w  M 2  M 3 *100%

8. Take soil sample in a evaporating dish . Mix the s ample with methylated spirit. M ethylated spirit required is one millilitre for every gram of soil. The methylated spirit is then ignited. The mixture is then stirred with spatula. After the methylated spirit has burnt away completely dish is allowed to be coo l and mass of dry soil is obtained . DISADVANTAGES-  Cannot be used if soil contain large proportion of clay and organic matter.  Methylated spirit is volatile so extra care is required.  Not accurate.

9. Equipments:- Containers Desiccator with any suitable desiccating agent Thermostatically controlled oven Weighing balance with accuracy of 0.01 gm

10. Clean the container, dry it and weight it with the lid. (M1) Take the required quantity of the wet soil specimen in the container & weight it with the lid.(M2) Place the container with its lid removed, in the oven till its weight become constant. When the soil has dried, remove the container from the oven . Find the weight M3 of the container with the lid and the dry soil sample.

11. M 3  M 1 Where, M 1 = mass of empty container M 2 = mass of container + wet soil M 3 = mass of container + dry soil w  M 2  M 3 *100 %

12. Principle used in t his method is that when water reacts with calcium carbide, acetylene gas is produced. PROCEDURE:- Wet sample is placed in a sealed container containing calcium carbide . The test require about 6 g of soil. The pressure of acetylene produced acts on the diaphragm of moister tester. The quantity of gas is indicated on a pressure gauge and water content is determined using pressure gauge .

13. Radioactive isotopes are used to determin e water content . A device containing a radio active isotopes material such as cobalt 60 is placed in a capsule . W hich is lowered in a steel casing. Steel casing has an opening from where rays come out. Another casing consist of detector which is placed in opening. Neutrons are emitted from radioactive material. Hydrogen atoms in water cause scattering of neutrons. As neutrons strike with hydrogen atoms they loose energy. The loss of energy released is proportional to the water content.

14. The specific gravity of solids is frequently required for computation of several soil properties such as void ratio, degree of saturation, unit weight of solids, fine soil particle size, etc. Methods used for determination are:- Pycnometer bottle method Density bottle method Measuring flask method Gas jar method Shrinkage limit method

15. Clean and dry the pycnometer . Find its mass with cap as W1 . Place about 200 gm of oven dried soil passing through 4.75 mm sieve. Determine mass of pycnometer with dry soil as W2 .

16. 4 Add water to the soil and see that soil should be soaked in water . Mix it t horoughly 20 to 30 minutes to remove air voids. 5 Add water upto the conical brim and wipe the bottle with dry cloth. 6 Determine mass of pycnometer with soil and water as W3. 7 Empty the pycnometer , clean it and wipe it dry. 8 Fill the pycnometer with distilled water and find its mass as W4. 9 C alculate the specific gravity of soil solids as under : G =[( W 2- W 1) / {( W 2- W 1)- ( W 3- W 4)}]

17. A density bottle of 50 ml capacity is used . Bottle is dried and cleaned at temperature of 105 -110 o C . Mass of bottle including stopper is taken . About 5-10g of soil is taken in the bottle and weighted . Distilled water is added to cover sample . The soil is allowed to soak water for about 30 minutes . The bottle is emptied, washed and refilled with distilled water . The mass of bottle filled with water is taken. DENSITY BOTTLE METHOD

18. Let W1 = mass of empty container W2 = mass of container + dry soil W3= mass of container + wet soil W4=mass of bottle filled with water G= [ ( W 2 - W 1 ) / {( W 2 - W 1 )- ( W 3 - W 4 )}] DENSITY BOTTLE METHOD

19. A measuring flask of 250 ml capacity, with a graduation marked at that level. It is fitted with an adaptor for connecting it to a vacuum line for removing entrapped air . This method is similar to density bottle method . About 80-100 g of oven drying sample is taken. Advantage - Suitable for fine grained and medium grained soil.

20. Determination of Field Density by Core Cutter Method Core cutter, Dolly & Rammer

21. Determination of Field/Bulk Density by Core Cutter Method

22. Measure the inside dimensions of the core cutter (Volume V) Determine empty weight of core cutter ( W1) Level the surface, about 300 mm square in area in the field . Place the dolly over the top of the core cutter and press the core cutter into the soil mass using the rammer. Stop the process of pressing when about 15 mm of the dolly protrudes above the soil surface. Remove the soil surrounding the core cutter and take out the core cutter. Remove the dolly. Trim the top and bottom surface of the core cutter carefully using a straight edge. Weight the core cutter filled with the soil (W2). Remove the core of the soil from the cutter. Determine the field density. Yb = (W2-W1)/V Determine water content by using oven drying method to find dry density

23. Bulk density, Dry density, Where, w is the water content DETERMINATION OF FIELD DRY-DENSITY M 1 M 2

24. 2. Field Density by Sand Replacement Method

25. Field Density by Sand Replacement Method

26.  Determination of Mass density of sand Volume of excavated hole Mass density of soil

27. Mass density of sand

28. Mass density of sand  Where , ‘’ M 1 initial mass of cylinder with sand  M 2 mass of sand in cone only  M 3 mass of cylinder after pouring sand into the cone and the container  V c volume of the container C s V 1 2 M  M  M 3  

29. Volume of the hole  Excavate a hole of 100mm diameter and a depth of 125 mm in the field. Where , M 1 initial mass of cylinder with sand  M 2 mass of sand in cone only  M 4 mass of cylinder after pouring sand into the hole   s mass density of sand s h V   1 2 M  M  M 4

30. Bulk density, V hole Dry density, Where, w is the water content M soil  

31. Particle size analysis is a method of separation of soils into different fractions based on particle size. Particle size analysis is done in 2 stages:- Sieve Analysis Sedimentation Analysis Sieve analysis is meant for coarse grained soil (particle size > 75 micron ). S edimentation analysis is for fine grained soils. ( particle size < 75 micron ). Sedimentation a nalysis Particle size smaller than 0.2 micron can be determined by an electron microscope or by X-ray technique.

32. Particle Size Distribution by Sieve Analysis Indian standard test sieves with opening of 4.75, 2.00, 1.00, 0.600, 0.425, 0.3, 0.150 and 0.075 (all in mm), suitable sized lid and pan, cleaning brushes, balances. sieve shaking machine.

33. Particle Size Distribution by Sieve Analysis: Sieve Shaker

34. PROCEDURE The test sample is dried to a constant weight at a temperature of 110 + 5 o C and weighed. The sample is sieved by using a set of IS Sieves. On completion of sieving, the material on each sieve is weighed. Cumulative weight passing through each sieve is calculated as a percentage of the total sample weight. Fineness modulus is obtained by adding cumulative percentage of aggregates retained on each sieve and dividing the sum by 100.

35. Sieve Size in mm Particle (Size in mm) Mass of Soil retained (gms) % mass retained Cum % mass retained % Finer 4.75 4.75mm 2.00 2.00mm 1.00 1.00mm 0.60 0.60mm 0.425 0.425mm 0.300 0.3mm 0.150 0.150mm 0.075 0.075mm

36. D 30 D 60 Particle size, D (mm) Percentage finer, N % 100 90 80 70 60 50 40 30 20 10 D 10 D 10 – Effective size Uniformity coefficient, Coefficient of curvature, D 10 D 60 C u  D 60  D 10 ( D ) 2 C c  30 Semi log Graph If Cu = 1 -----------> poorly/ uniformly graded soil If Cu > 4- ------------> gravel If Cu > 6 ------------> sand If Cu > 4 to 6 -----> well graded soil and Cc = 1 to 3------> well graded soil

37. ( Semilog graph)

38. ( Semilog graph)

39. 32 Log scale Effective size D 10 : 0.02 mm

40. The consistency of a fine grained soil is the physical state in which it exists. The water content at which the soil changes from one state to other are known as consistency limits or ATTERBERG limits. At the same water content one soil may be relatively soft, whereas another soil may be hard. Thus consistency limits are very important properties of fine grained soil.

41. 34 Atterberg’s consistency limits Atterberg limits are the water contents at which soil mass passes from one state to the next. The Atterberg limits are based on the moisture content of the soil. Atterberg States: Liquid Plastic Semisolid Solid

42. 34 Atterberg’s limits Liquid limit (W L ) is the water content at which the soil, changes from liquid to plastic state liquid. Soil is still in liquid state and has small shearing strength against flowing. Plastic limit (W P ) is the minimum water content at which the soil can be rolled into a thread of 3 mm in diameter without crumbling.

43. 34 Atterberg limits Shrinkage limit (W S ) is the water content after which further loss of moisture doesn’t cause a decrease in the volume of the soil. Shrinkage limit is a lowest water content at which a soil can still be completely saturated. At Shrinkage limit the shrinkage ceases.

44. Liquid Limit By Casagrande’s Method

45. The liquid limit device is adjusted to have a free fall of cup of 1cm this is done with the help of adjusting screw provided near the cup hinge. Take 100gm of soil sample after passing from 425µ IS sieve. Add 15% water in soil by weight of soil. Mix it thoroughly to make uniform paste. Put wet soil in cup and leveled it at lowest spot and squeezed down with spatula to have a uniform space. Then with the help of casegrande’s tool , divided into two parts by grooving up to bottom surface of cup . https://www.youtube.com/watch?v=GxXqqIuCfT0

46. Rotate handle at the rate of 2 revolutions per second and cup will start process of up and down. Count the rotation of handle until the bottom surface of groove is connected. Take fresh sample and increase 3% water to initial water content and repeat the steps 4 to 8 . Enter No of blows against each water content in the tabular form. The process of adding water is contained until connecting of groove is completely in 1 5 to 40 blows. Draw the graph, No of blows Vs Water Content on semi-log graph to get W L against 25 number of blows.

47. Flow index I f  = (W 2 -W 1 )/log(N 1 /N 2 ) = slope of the flow curve

48. The minimum water content at which a soil will just begin to crumble when it is rolled into a thread of approximately 3 mm in diameter. When point is reached where thread is cracking and cannot be re-rolled to 3 mm diameter, collect at least 6 grams and measure water content. The test is repeated taking a fresh sample each time. Plastic limit is taken as average of three values. https://www.youtube.com/watch?v=b9HvDB8G90k

49. Plasticity Index is the numerical difference between the Liquid Limit w% and the Plastic Limit w % Plasticity Index ( Ip ) = Liquid Limit (W L ) - Plastic Limit ( Wp ) P I / Ip = (W L – Wp ) TYPE LIQUID LIMIT Low plasticity < 35% Intermediate plasticity 35 - 50% High plasticity 50 - 70% Very high plasticity 70 - 90% Extremely high plasticity > 90% Ip Plasticity Non plastic < 7 Low plastic 7 – 17 Medium plastic > 17 Highly plastic

50. Plasticity chart is drawn W L vs Plasticity Index

51. Plasticity chart is drawn W L Vs Plasticity Index

52. The soils which show higher shrinkage upon drying also swell more upon wetting and are known as expansive soils. Expansive soils are very dense and hard in dry state due to very high shrinkage stresses Shrinkage cracks in a lake which dried due to drought

53. Shrinkage Limit

54. Shrinkage Limit

55. Shrinkage Limit

56. Shrinkage Limit

57. Shrinkage Limit

58. Toughness, Liquidity and Consistency Index Toughness Index (I T ) = Ip /I f Larger value of IT indicates better strength at its Wp Liquidity Index I L = (w – Wp )/ Ip Consistency Index / Relaative consistency ( Ic ) Ic = (W L -w)/ Ip Ic is useful to study the saturated field behaviour of fine grained soils If Ic = 1, soil at its Wp Ic = 0, soil is at its W L Ic => 1, soil is in semisolid state and stiff Ic = ‘-’, w > W L and soil behaves like liquid

59. Plasticity Ratio and Activity Liquidity Index I L is also called as water plasticity ratio Ic + I L =100% Activity Number(A) : It is the ratio of the plasticity Index to the % of clay fraction. It is the measure of water holding capacity of clay. A = Ip / C Swelling and shrinkage characteristics are represented by A. If A < 0.75, inactive A = 0.75 to 1.25, normal A > 1.25, active If clay contains Montmorillonite mineral, A > 4,very high. For a specific origin of soil, A is constant

60. If particle size, decreases, W L , Wp and PI –> increases If silt is added to clay, W L , Wp and PI –> decreases Silt y soil contains fine particles but it doesn’t have cohesiveness /stickiness Consistency is the resistance offered by soil against deformation and it varies with water Plasticity is the property that allows it to be deformed without rupture

61. The relative density is generally used to indicate the in situ (on site) denseness or looseness of soil. It is defined by :-

62. where, m i n m a x e max  void ratio of thesoil in loosest state e min  void ratio of thesoil in the denseststate e  void ratio for in situ. e max  e e  e D  r The relative density is generally used to indicate the in situ (on site) denseness or looseness of soil. It is defined by :-

63. The relative density of a soil give more clear idea of denseness than does the void ratio. Two types of sand having same void ratio may have entirely different state of denseness. However if two sands have same relative density, they usually behave in identical manner. The Relative Density of soil indicates how it would behave under the loads . If the deposit is dense it can take heavy loads with very little settlement. Depending upon the relative density, soils are generally divided into 5 categories:- RELATIVE DENSITY (%) DENSENESS <15 Very loose 15-35 Loose 35-65 Medium Dense 65-85 Dense 85-100 Very Dense

64. Thank You Reference from internet and text books