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Cold Asphalt - Emulsion Aggregate Mix

Cold Asphalt / Cold Mix / Emulsion Aggregate Mix

What is Cold Asphalt ?

Cold asphalt is green technology for construction of bituminous road which complies mixture of Bitumen Emulsion, Aggregates and Filler. Cold Asphalt is very useful for potholes repair, emergency road construction. Cold Asphalt is specially used for overlay work in rural and hilly roads where average temperature is below 15 degree Celsius. Density of Cold Mix or Cold Asphalt is 2190 Kg/m3.


Contradict to hot mix asphalt or premix, cold mix or cold asphalt does not require heating for production. Cold Asphalt can be produced on-situ  with limited resources and manpower. Cold Mix is efficient in all types of weather/climate : hot, cold or even wet. 

Norms For Cold Asphalt:

Providing, laying and rolling of bituminous cold mix on prepared base consisting of a mixture of unheated mineral aggregate and emulsified bitumen, including mixing in a plant of suitable type.

Requirements for producing 205 m3 or 450 tonne of Cold Asphalt:

  • Labours: 
    • Skilled: 6 Days
    • Unskilled: 16 Days 
  • Materials: 
    • Bitumen Emulsion: 36 tonne (175 lit/m3)
    • Water: (L/S for workability)
    • Aggregate:
      • For 20 mm Thickness
        • 13.2 Down: 75 m3
        • 9.5 Down: 87 m3
        •  6 mm Down: 108 m3
        • Filler (Lime or Cement): 9 tonne (Appox 1 Bag/m3)
      • For 40 mm Thickness
        • 37.5 down: 75 m3
        • 19 down: 90 m3
        • 6 mm down: 105 m3
        • Filler (Lime or Cement): 9 tonne (Appox 1 Bag/m3)
  • Equipment:
    • Concrete Mixture: 6 hours 
    • Tandem Roller: 6 hours
    • Pneumatic Roller: 6 hours 
    • Paver Finisher: 6 hours (Not required in all cases, skilled manpower is used for laying)

Process of Producing Cold Mix / Cold Asphalt:

  • Prepare batch of 0.05 m3 of aggregate (mixture in ratio) and feed into concrete mixture or lay on ground (if manual).
  • Pour 8.75 lit of Rapid Setting/Medium Setting Emulsion into concrete mixture or over aggregate (if manual).
  • Allow mixing for 45 sec until all the aggregate are well mixed in emulsion. Quickly spread the grey aggregate mix over surface to be lay. If hand mixed, mix until all the aggregate turns grey in color. Mix water to increase workability.
  • Compact the overlay cold mix with tandem with 2 pass. 
  • Spray filler (lime or cement) over the surface once when the area tends to 50 sq.m and allow pneumatic roller to compact.
  • Make final roll by tandem roller and the road is ready to serve.
 
Picture: Cold Asphalt Overlay in Nepal in Extreme Cold Climate

Advantages of Cold Mix / Cold Asphalt / EAM:

  • Easy Setup: No expensive batching plant required for production. A normal concrete mixture or even hand mixing can be done for the work.
  • Durable: Road constructed by Cold Mix are durable. Those roads are intended to last longer than that of hot mix overlay. Cold Mix is suitable even in extreme cold climate and less susceptible to water.
  • Quick: Any potholes and crack can be treated quickly. 
  • Cheaper: Although, it seems expensive in beginning, but in long run, it is cheaper than hot mix due to least repairing cost. 
  • Green Technology: No fuel required to heat aggregate and bitumen, no pollution at all.

Limitations of Cold Mix / Cold Asphalt / EAM:

  • Laying work should be quick. Cold Asphalt begin to harden/set within 2 min of mix.
  • Manpower required is more as compared to hot mix. 
Conclusion: Cold Asphalt is green technology for construction of bituminous road providing durable road with limited resources in low cost. Cold Asphalt is suitable for rural road where resources are limited. Cold Asphalt is one and only option in extreme cold climate where hot mix is not feasible.

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