Highway Construction Materials and Practice

Sub grade soil is an integral part of the road pavement structure as it provides the support to the pavement from beneath.

The sub grade soil and its properties are important in the design of pavement structure.

The main function of the sub grade is to give adequate support to the pavement and for this the sub grade should possess sufficient stability under adverse climatic and loading conditions.

1. UNIT IV HIGHWAY CONSTRUCTION MATERIALS AND PRACTICE M.Senthamizhan Assistant Professor / Civil Alagappa Chettiar Government College of Engineering and Technology, Karaikudi Tamilnadu

2. CONTENT Highway Materials – Properties and Tests Subgrade Soil Stone Aggregates Bituminous Material Concrete Highway Construction Flexible Pavement Rigid Pavement Highway Drainage Surface Drainage Sub Surface drainage Highway Construction Machineries

3. Highway Material Subgrade Soil

4. Su b gr a d e soi l is an int e gr a l par t of the roa d p a v e m e n t structure as it provides the support to the pavement from b e neat h . T h e s ub g r ad e so i l a n d its prop e rtie s are important in t h e d esig n of pav e m e n t s t r u ctu r e . Th e ma i n function of the sub grade is to give adequate support to the pavement and for this the sub grade should possess sufficient stability under adverse climatic and loading conditions. Subgrade Soil

5. Properties of Subgrade Soil The desirable properties of sub grade soil as a highway material are Withstand capability (Stability) Ease of compaction. Strength permanency Low change in volume during adverse conditions of weather and ground water table. Superior drainage Incompressibility

6. Classification of Soil based on grain size

7. Textural Classification of Soil

8. Tests on Subgrade Soil The tests used to evaluate the strength properties of soils may be broadly divided into three groups:

9. Direct Shear Test

10. Direct Shear Test

11. Triaxial Compression Test

12. Plate Bearing Test

13. California Bearing Ratio Test (CBR Test)

14. Highway Material Stone Aggregates

15. Stone Aggregate The major portion of the pavement structure Bear the stresses occurring due to the wheel loads on the pavement Used in pavement construction, cement concrete, bituminous concrete and other bituminous construction Most of the road aggregates are prepared from natural rocks They are specified based on their grain size, texture and its gradation

16. The desirable properties of stone aggregate as a highway material are Strength Hardness Toughness Durability Shape of Aggregates Adhesion of Bitumen Stone Aggregate

17. The tests used to evaluate the strength properties of stone aggregates Stone Aggregate

18. Aggregate - Crushing Test

19. Aggregate – Abrasion Test (Los Angeles)

20. Aggregate – Abrasion Test ( Devals )

21. Aggregate – Abrasion Test ( Dorry )

22. Aggregate – Impact Test

23. Aggregate – Soundness Test

24. Aggregate – Shape Test – Flakiness Test

25. Aggregate – Shape Test – Flakiness Test

26. Aggregate – Shape Test – Elongation Test

27. Aggregate – Shape Test – Angularity Index

28. Aggregate – Specific Gravity

29. Aggregate – Water Absorption

30. Aggregate – Bituminous Adhesion Test Bitumen adheres well to all normal types of road aggregates provided they are dry and free from dust. In the absence of water there is practically no adhesion problem of bituminous construction. Adhesion problem occurs when the aggregate is wet and cold. This problem can be dealt with by removing moisture from the aggregate by drying and increasing the mixing temperature. Further, the presence of water causes stripping of binder from the coated aggregates. This problem occurs when bitumen mixture is permeable to water. Several laboratory tests are conducted to arbitrarily determine the adhesion of bitumen binder to an aggregate in the presence of water. Static immersion test is one specified by IRC and is quite simple. The principle of the test is by immersing aggregate fully coated with binder in water maintained at 40 C temperature for 24 hours.

31. Highway Material Bituminous Material

32. Bituminous Material Bituminous binders used in pavement construction works include both bitumen and tar Bitumen is divided into two category as Petroleum Asphalt or bitumen and Natural Asphalt . The grades of bitumen used for pavement construction work of roads and airfields are called paving grades Those used for water proofing of structures and industrial floors etc. are called industrial grades A – Type : Paving Bitumen from Assam Petroleum, Grades are A35 and A90 S – Type : Paving Bitumen from Other sources, Grades are S35 and S90

33. Bitumen vs Tar

34. The desirable properties of Bitumen as a highway material are Mixing Attainment of desired stability of the mix To maintain the stability under adverse weather conditions To maintain sufficient flexibility and thus avoid cracking of bitumen surface To have sufficient adhesion with aggregates in the mix in the presence of water. The material should be durable Bitumen Material

35. The tests used to evaluate the strength properties of Bitumen Bitumen Material

36. Bitumen – Penetration Test

37. Bitumen – Penetration Test

38. Bitumen – Ductility Test

39. Bitumen – Ductility Test

40. Bitumen – Viscosity Test

41. Bitumen – Float Test

42. Bitumen – Specific Gravity Test

43. Bitumen – Softening Test

44. Bitumen – Flash & Fire Test

45. Bitumen – Solubility Test

46. Bitumen – Spot Test

47. Bitumen – Loss of Heating Test

48. Bitumen – Water Content Test

49. Highway Pavement

50. PAVEMENT- Pa v ement is l oa d b eari n g a n d l o a d distributery component of a road . PURPOSE OF PAVEMENT- Load support. Smoothness. Drainage. All weather operation. Direction and guidance.

51. Highway Construction Flexible Pavement

52. Flexible pavement: Flexible pavements are so named because the total pavement structure deflects, or flexes, under loading. A typically composed of several layers of material.

53. STRUCTURE OF FLEXIBLE PAVEMENT

54. Load distribution in flexible pavement

55. Subgrade: The subgrade is the compacted soil layer that forms the foundation of the pavement system. It is also known as the "Formation Level“.

56. CONSTRUCTION OF SUBGRADE Removal of top soil (If not suitable for sub grade or to match the level) Removal of vegetation and other harmful material Lay down the Soil in layers of 266mm (max.) Compaction of Layer ( After Compaction Max. depth should be 200mm) Further Layer of Soil Compaction of Layer

57. PREPARATION OF SUBGRADE

58. PREPARATION OF BASE COURSE

59. The aggregate to be used for the BM layer shall fulfil the specified gradation. Two type of aggregate gradation have been specified by the IRC which is as given below table

60. The base on which bituminous macadam is to be laid shall be prepared, shaped and compacted to the required profile. The prime coat and take coat are applied as specified. The BM mix is prepared in a hot mix plant at specified temperature, depending on the grade of the bitumen used. The hot mix is transported to the construction site in insulated covered truck. The BM mix is spread using a mechanical paver. Bituminous materials shall be laid and compacted in layers, which enable the specified thickness, surface level, regularity requirements and compaction to be achieved.

61. Binder course: This layer provides the bulk of the asphalt structure. It's main purpose is to distribute load.

62. PREPARATION OF BINDER COURSE

63. Tack coat : it is high viscous bituminous material(100% bitumen)

64. Surface C ourse : The surface course is the layer in contact with traffic loads and normally contains the highest quality materials.

65. S eal coat : I t is the asphalt-water mixture to seal cracks on surface layer.

66. Highway Construction Rigid Pavement

67. Rigid pavements, though costly in initial investment, are cheap in long run because of low maintenance costs, The cost of construction of single lane rigid pavement varies from 35 to 50 lakhs per km in plain area, Rigid pavement have- Deformation in the sub grade is not transferred to subsequent layers Design is based on flexural strength or slab action Have high flexural strength No such phenomenon of grain to grain load transfer exists Have low repairing cost but completion cost is high Life span is more as compare to flexible (Low Maintenance Cost)

68. PROCEDURE TO CONSTRUCT THE RIGID PAVEMENT ROAD

69. Rolling on sub grade by roller Filling the granular soil in the weak part and pot holes Cor r ect the soi l c o a t , Cam b er , longi t udi n al slop e When concrete direct laid on subgrade, For preventing the water-seepaging into the soil , used water proof paper on entire length.

70. PREPERATION OF SUB GRADE

71. Choose any one type of base W.B.M. base As base material of W.B.M. Road; stone ballast, concrete 10-15cm layer are used. For bonding between concrete slab & W.B.M. used 1:2 cement wash on W.B.M. Concrete base On the road used 10cm Cement concrete(1:2:4) or lime concrete 3 . Granular medium material layer 10-15cm composite layer of sand , moorum are used for better drainage facilities 4. Stabilization soil

72. Material for form work- W o o de n she e ts, b a t t e n s , p l y w o o d , f i b r e ha r d board, steel plates, angles, rope, minerals . B efore using form work, it should free from all type material like as dust ,cement. T o p l acing the c onc r e t e i n app r opr i a t e d ep th used 2.5-5cm thick and 3mtr long wooden sheeting . 3. The depth of wooden block must be same as level of slab thick. 4. After 24hrs form work displaced next length of road.

73. Where is necessary to provide transverse, Longitudinal joints; there wedge of woods, metals fix on level of concrete. After setting of concrete it should be pull out. If provided the dowel bar in joints, bars should be fit at right position.

74. Mixer is equipment that mix the concrete using distinct amount of cement , concrete, sand and water. Concrete slab should have more than 5-10cm thick cause of drying. Used two type mixer- Batch mixer- at site, used for small road construction Continuous mixer- Continuous mixer used for large construction . if distance is more from site , mix concrete transported at site within setting time.

75. Methods Placing Concrete

76. Purpose of compaction is that to pull out air from void and make concrete harden. 1. M echanically surface vibrator 2 . M anually hand tempers 7.Compaction

77. 8. Finishing of S urface Floating- For levelling the surface use floating , scree- ding , power trowel. So that there is no acceptable more than 3mm variation in concrete level surface. Belting- For making surface clean used belting process. Belt is nothing but a 15-30cm thick sheets of canvass which have more length than road.

78. 8. Finishing of S urface 3. Brooming- Brooming is the process in which we made rough surface parallel to road by brush. It useful in avoiding slip & comfortable travelling on road . T he depth of line on road no more than 1.5mm.

79. 9 . Curing Curing is the name of increasing the hydration process of cement. A fter setting the concrete , curing process done till 14 - 28days .

80. 10. Filling Joint After drying road, clean the joints and fill the shelling compound or hot bitumen also bitumen fill road bank.

81. 11. Edging To protect damaging the sides of concrete pavements used over burnt brick work. I n place of brick, provided kerb of pre mix concrete.

82. Generally after a month, road should be open to traffic. If used rapid hardening cement it take 7 days to open traffic.

83. Type of Joints in Rigid Pavement

84. Highway Drainage Highway drainage is a process of removing and controlling excess surface and sub-soil water within the right of way. It includes interception and diversion of water from the road surface and sub grade.

85. Significance of Highway Drainage Excess moisture - lowering of its stability and strength in Pavement Sustained contact o f water - pot holes Excess water on shoulders - considerable damage . In clayey soil variation in moisture content – Change in volume of sub grade. Erosion of soil from top of unsurfaced roads and slopes of embankment, cut and hill side is also due to surface water. In cold regions presence of water in the subgrade and a continuous supply of water from the ground water can cause considerable damage to the pavement due to frost action .

86. Requirements of Highway Drainage The surface water - drained off without allowing it to percolate to sub grade. Side drain should have sufficient capacity and longitudinal slope to carry away all surface water collected. Flow of surface water across the road and shoulders and along slopes should not cause formation of cross ruts or erosion . Seepage and other sources of under ground water should be drained off by the subsurface drainage system. Highest level of ground water table should be kept well below the level of subgrade, preferably by at least 1.2m. In waterlogged areas special precautions should be taken, especially if detrimental salts are present or if flooring is likely to occur .

87. Surface – Longitudinal Side Drains a. Side Drain for Road Embankment b. Side Drain for Road cutting

88. Surface – Catch Basin & Inlet a. Catch Basin b. Inlet

89. Surface – Shoulder Drainage

90. Surface – Median Drainage

91. Sub Surface – Lowering the Water Table

92. Sub Surface – Controlling Seepage Flow a. Above the subgrade of pavement b. At or below the subgrade of pavement

93. Sub Surface – Controlling Capillary Water

94. Highway Machineries