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Unit 5

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Unit 5

  1. 1. By- MD MOZAFFAR MASUD Assistant Professor Department of Civil Engineering JIT, JETGI, Barabanki
  2. 2. Typical layers of a flexible pavement  Seal Coat: Seal coat is a thin surface treatment used to water-proof the surface and to provide skid resistance and to seal the surfacing against the ingress of water.  Tack Coat: Tack coat is a very light application of asphalt, usually asphalt emulsion diluted with water. It provides proper bonding between two layer of binder course.it is generally applied on impervious surface.  Prime Coat: Prime coat is an application of low viscous liquid bituminous material over an existing porous or absorbent pavement surface like WBM.  Prime objective is to plug the capillary voids of the porous surface and to bond the loose materials on the existing surface like granular bases on which binder layer is placed. It provides bonding between two layers.
  3. 3. LAYERS OF CARRIAGEWAY EARTH WORK GRANULAR SUB BASE(GSB) WET MIX MACADAM(WMM) BITUMINOUS MACADAM(BM) BITUMINOUS CONCRETE(BC) TACK COAT
  4. 4. EARTH WORK  SOIL FILLING  SPREADING & LEVELING  COMPACTION
  5. 5. COMPATION OF SUBGRADE I LAYER :200mm II ,III LAYER :150mm
  6. 6. GRANULAR SUB BASE  MATERIAL  LAYERS  DEPTH  COMPACTION
  7. 7. Sub Base Layer
  8. 8. It is a road base material consisting of crushed rock/slag usually premixed with controlled amount of water sufficient for adequate compaction.
  9. 9. BITUMINOUS MACADAM > Bituminous macadam consists of aggregate and appropriate binder, mixed in a hot mix plant and laid with a mechanized paver. > It is an open graded mixture suitable for base course and is laid in a single course or in multiple layers on a previously prepared base.
  10. 10. FINISHING OF SURFACE(ROLLING)
  11. 11. AGGREGATE  COARSE AGGREGATE The coarse aggregate consists of crushed rock, crushed gravel or other gravel or other hard material retained on 2.36mm sieve. FINE AGGREGATE Fine Aggregate consist of crushed or naturally occuring material or their combination passing 2.36 mm sieve and retained on 75 micron sieve.
  12. 12. BITUMINUS CONCRETE  MATERIAL  MIXING  SPREADING
  13. 13.  Sufficient bitumen to ensure a durable pavement.  Sufficient strength to resist shear deformation under traffic at higher temperature.  Sufficient air voids in the compacted bitumen to allow for additional compaction by traffic.  Sufficient workability to permit easy placement without segregation.  Sufficient resistance to avoid premature cracking due to repeated bending by traffic.  Sufficient resistance at low temperature to prevent shrinkage cracks. OBJECTIVES OF BITUMINOUS MIX DESIGN
  14. 14. Requirements of Bituminous mixes  Stability  Durability  Flexibility  Skid resistance  Workability  Desirable properties
  15. 15.  Coarse aggregate (retained on 2.36mm sieve)  Fine aggregate (passing 2.36mm sieve but retained on 75m)  Filler (passing 75m), may be cement.  Binder: Bitumen etc. CONSTITUENTS OF BITUMEN MIX
  16. 16. DEFINITIONS  Binder: A material used to hold solid particles together, i.e. bitumen or tar.  Bitumen: A heavy fraction from oil distillation (also occurs as part of natural asphalt).  Tar: A viscous liquid obtained from distillation of coal or wood. Rarely used in construction currently in the UK.  Asphalt: A mixture of bitumen and mineral filler. Note that Hot Rolled Asphalt is a road surfacing material.  Mastic: An adhering asphalt which is placed with trowelling.  Macadam: A road construction material with binder and coarse aggregate. Tarmacadam was the first road surfacing material.
  17. 17. BITUMINOUS CONSTRUCTION PROCEDURES  Surface Dressing  Grouted Or Penetration Macadam  Built-up Spray Grout  Bitumen Bound Macadam  Bituminous Carpet  Bituminous Concrete
  18. 18. ASPHALT CONCRETE OR (BITUMINIOUS MIXTURE)  Asphalt concrete is a composite material commonly used in construction projects such as road surfaces, airports and parking lots. It consists of asphalt (used as a binder) and mineral aggregate mixed together  Hot mix asphalt concrete (commonly abbreviated as HMAC or HMA) is produced by heating the asphalt binder to decrease its viscosity, and drying the aggregate to remove moisture from it prior to mixing  Warm mix asphalt Concrete (commonly abbreviated as WMA) is produced by adding either zeo-lites waxes, asphalt emulsions, or sometimes even water to the asphalt binder prior to mixing  Cold mix asphalt concrete is produced by emulsifying the asphalt in water with (essentially) soap prior to mixing with the aggregate  Cut-back asphalt concrete is produced by dissolving the binder in kerosene or another lighter fraction of petroleum prior to mixing with the
  19. 19. Mastic asphalt concrete or sheet asphalt is produced by heating hard grade blown bitumen (oxidation) in a green cooker (mixer) until it has become a viscous liquid after which the aggregate mix is then added. Natural asphalt concrete can be produced from bituminous rock, found in some parts of the world, where porous sedimentary rock near the surface has been impregnated with upwelling bitumen. HOT MIX ASPHALT HMA is a mixture of coarse and fine aggregates and asphalt binder. HMA, as the name suggests, is mixed, placed and compacted at higher temperature. Dense-Graded Mixes This type of bituminous concrete is a well-graded HMA has good proportion of all constituents are also called Dense bituminous macadam. Dense graded HMA surface Dense graded core sample
  20. 20. Stone Matrix Asphalt (SMA) Stone matrix asphalt (SMA), sometimes called stone mastic asphalt, is a gap- graded HMA originally developed in Europe to maximize rutting resistance and durability in heavy traffic road. SMA Lab Sample SMA Surface Open-Graded Mixes Unlike dense-graded mixes and SMA, an open-graded HMA mixture is designed to be water permeable. Open-graded mixes use only crushed stone (or gravel) and a small percentage of manufactured sands
  21. 21. CHARACTERISTICS OF MATERIAL USED IN BITUMINOUS MIX • Mineral Aggregate Obtained from different natural sources such as glacial deposits or mines.  A highly cubic shape and rough texture to resist rutting and movements.  A hardness which can resist fracturing under heavy traffic loads.  A high resistance to polishing, and  A high resistance to abrasion. Mineral filler Generally filler plays an important role in properties of bituminous mixture particularly in terms of air voids, voids in mineral aggregate. Different types of mineral fillers are used in the SMA mixes such as stone dust, ordinary Portland cement (OPC), slag cement, fly Ash, hydrated lime etc
  22. 22. • Binder Bitumen acts as a binding agent to the aggregates, fines and stabilizers in bituminous mixtures. Binder provides durability to the mix. • Stabilizing Additives The main stabilizing additives used in mixes can be classified in to different groups;  Fibres’ (Cellulose Fibres, Mineral Fibres, Chemical Fibres) Polymer Powder and flour like materials (Silicic acid, Special Filler) Plastics (Polymer Powders or Pellets)  Natural fiber:-Natural fiber classified into 3 category depending upon the part of plant from where it is extracted  Stem fiber (jute, banana etc.)  Leaf fiber (sisal, pineapple)  Fruit fiber (cotton, coir, oil palm)
  23. 23. Conventional Bituminous Mix Technologies • Hot Mix Technologies- Shortfalls  Heating of binder at 150- 170°C Heating of aggregates at 185- 200°C Production at 150-160°C Laying at 140°C Compaction at 120 °C Environmental pollution High energy consumption Limited work year
  24. 24. COLD BITUMINOUS MIXES • Cold mix technology eliminates heating of aggregates, bitumen binder, uses cationic bitumen emulsions. • Optimized composition of open graded premix carpet, semi- dense bituminous concrete, microsurfacing and bituminous macadam . • It is environment friendly, offer greater social acceptance, increased paving period, acceptable performance and cost effective. Technology has found wide acceptance.
  25. 25. PRODUCTION OF COLD MIXES Adding Pre-mix Water Adding Emulsion In Drummixer Cold mix on coneyer belt Discharge of cold to dumper
  26. 26. PREPARATION OF COLD MIX Charging of Aggregates Wetting of Aggregates Emulsion for Cold Mix Discharging of Cold Mix
  27. 27. • Transportation of cold mix  Cold mix shall be discharged in trolleys/wheel barrow  Cold mix shall be transported to site by wheel barrow/tippers  Avoid newly laid surface or tacky road surface while ferrying • Spreading of cold mix  Spread cold mix in half the road-width  Required thickness with spreader  Cold mix turned black from brown  Cold mix aerated for about one hours • Compaction  Compacted with 8-10 ton road roller  Wetting of wheels
  28. 28. APPLICATIONS OF BITUMEN EMULSIONS • Tack coat & priming • Crack filling and sealing • Repair of pot- holes & depression • Surface dressing • Premix Carpet • Bituminous Macadam • Micro surfacing • Repair of utility cuts
  29. 29. CC Pavement  Cement concrete pavements are generally constructed using plain cement concrete slab.  CC pavement serves good & durable wearing surface as well as an effective and strong base course.  The routine and periodic maintenance cost is very low as maintenance of joints only required .  The life cycle cost of CC pavement are much lower then flexible pavements.  CC pavements are generally designed and constructed for 30 years.
  30. 30. MATERIALS FOR CONSTRUCTIONS  Portland cement  Coarse aggregate  Fine aggregate  Water  Steel bars  Admixtures etc.
  31. 31. AGGREGATE  Coarse aggregates used for construction shall fulfill the following requirements : 1) Los Angeles abrasion value - < 35% 2) Flakiness & Elongated index - < 35% 3) Water absorption - < 3%  max size 31.5 mm  Fine aggregates shall be : 1) Well graded. 2) 100% passing 10mm sieve.
  32. 32. COMPONENTS OF CC PAVEMENT  Sub grade  Drainage layer  Sub base coarse dry lean concrete (DLC) layer to support cc slab & better drainage.  Separation membrane prevent sticking b/w new concrete(cc slab) and old concrete (DLC).  Pavement slab to withstand over flexural stress.
  33. 33. PREPARATION OF CONCRETE Recommended water content and workability  W-C ratio shall not exceed 0.45.  Slump of concrete mix compacted by vibration shall be in range 25 ± 10 mm.  Generally M40 concrete is used in cc road for which approximate w-c ratio is 0.38.
  34. 34. MIXING  Mixing of concrete is done by two methods. These are as following. a. Hand mixing b. Machine mixing
  35. 35. TRANSPORTING AND PLACING
  36. 36. FORMWORK
  37. 37. CONSTRUCTION STEPS  Construction of sub-grade.  Construction of drainage layer.  Construction of sub-base course.  Laying of separation membrane.  Construction of CC pavement slab.
  38. 38. CONSTRUCTION OF CC SLAB Operations involved in it 1. Spreading the prepared concrete mix to desire thickness 2. Compacting 3. Curing 4. Cutting of joints
  39. 39. COMPACTING Internal vibrator Surface vibrator
  40. 40. CURING  Curing is the term used for the job of keeping the fresh concrete wet till desired purpose of ensuring complete setting and hardening of cement in the concrete is achieved.  Curing of concrete is contain many steps: a) Objects of curing. b) Methods of curing. c) Time required for curing.
  41. 41. PONDING CURING
  42. 42. JOINTS  Contraction joints  Expansion joints  Construction joints  Longitudinal joints
  43. 43. OPENING TO TRAFFIC • Usually, a concrete pavement is only opened to traffic 7 days after the concrete has been laid and after, in the presence of all parties, any possible cracks have been recorded. • A concrete pavement of less than 7 days old, can be opened to traffic if the contractor provides proof that the concrete has reached the minimum compressive strength stipulated in the specifications. • Special compositions of the concrete mix allow an early opening to traffic.

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