Drawback to use Cutback bitumen
- 1.as the solvent evaporates into the atmosphere which is a costly affair.
- 2. The solvent which evaporates into the atmosphere is a cause of air pollution
- 3. Due to the use of solvent, it has a low flash point and causes safety issues
- Hence it is a good option to use Emulsified Bitumen
- The emulsion is a two-phase system of two unmixable liquid.
- There is bitumen that is in the dispersed phase and water is in the continuous phase.
- we add emulsifiers in small quantity, the main function of emulsifiers is
- 1. Formation of dispersion of bitumen and
- 2. To keep the globules of dispersed bitumen in permanent suspension
- Emulsifiers do not allow the Oil (bitumen) to separate from the water
- An example of an emulsifying agent is a soap for both cationic or anionic.
- As per IS 3117: 2004 or IS 8887: 2018 Emulsified bitumen shall be of the following three types
- a). Rapid setting: Type RS
- b) Medium setting: Type MS
- c) Slow Setting: Type SS
- Type and amount of emulsifying agent controls the setting rate of emulsion
- Rapid set emulsion = mixed with the Smallest quantity of the emulsifying agent.
- Slow set emulsion = mixed with the highest quantity of the emulsifying agent.
- The rapid set emulsion is designed to react quickly with aggregate and restore from the emulsion to the bitumen.
- Slow set emulsion restores slowly from the emulsion to the bitumen.
- Never mixed cat-ionic emulsion with anionic emulsion or in other words never mixed emulsion.
- Bitumen particles may stick to each other. the reason may be
- 1. low quantity of emulsifiers agent
- 2. thermal shock to emulsions
- 3. storage for long-duration hence As per IS 3117: 2004 or IS 8887: 2018
- The requirement from emulsion: Bitumen emulsion shall be homogeneous. Within one year after manufacture it shall show no undispersed bitumen after thorough mixing. and shall comply with the requirement of IS 3117: 2004 and IS 887: 2018.
Emulsion chemistry of Anionic Bitumen
- Anionic Bitumen Emulsion is to be used with positive charge particles aggregate for good bonding.
- Limestone is a positive charge aggregate so there is good bonding
- should be as per IS 3117: 2004
- Not widely used in India
Cationic Bitumen Emulsion
- Cationic Bitumen Emulsion is to be used with negative charge particles aggregate for good bonding.
- Silica gravel is a negative charge aggregate so there is a good bonding
- should be as per IS 8887: 2018
- widely used in India.
- As per IS 8887: 2018 clause 5 Emulsified bitumen shall be of the following five grades: Grade
- a) Rapid Setting-1 RS-1
- b) Rapid Setting-2 RS-2
- c) Medium Setting MS
- d) Slow Setting-1 SS-1
- e) Slow Setting-2 SS-2
- 6.1 Bitumen emulsion shall be homogeneous. Within one year after manufacture date, it shall show no undispersed bitumen after thorough mixing.
- 6.2 The physical and chemical requirements of the five grades of emulsion shall comply with the requirements specified in Table 1.
- 7.1.c The sample of bitumen emulsion shall be drawn within 24 h after delivery and tested within 7 days from the date of the drawing, unless otherwise specified
- Recommended uses as per IS 8887: 2018
- RS-1: especially recommended for tack coat applications
- RS-2: especially recommended for surface dressing work
- MS: to be used for plant or road mixes with coarse aggregate minimum 80 percent, all of which is retained on 2.36 mm IS Sieve and practically none of which passes 180 microns IS Sieve, and also for surface dressing and penetration macadam
- SS-1: used for other applications such as fog seal, crack sealing, prime coat applications.
- SS-2: used for plant or road mixes with graded and fine aggregates, a substantial quantity of which passes a 2.36 mm IS Sieve, and a portion of which may pass a 75-micron IS Sieve. Examples of its uses are cold mixed MSS (Mixed Seal Surfacing), SDBC (Semi Dense Bituminous Concrete) and slurry seal.
Viscosity of Emulsion
- Asphalt content: Low asphalt content imparts low viscosity and high asphalt content high viscosity
- Poor packing of bitumen in the emulsion is more stable and imparts high viscosity.
Emulsion price in India
please visit on the link for today price : https://www.iocl.com/Product_PreviousPrice/EmulsionPreviousPrice.aspx
Do and Don’t
- store the bitumen emulsion between 10 degrees C to 85 degrees C.
- It is not advisable to heat the bitumen emulsion above 85 degrees C, as it may evaporate water and changing the characteristics of the bitumen emulsion.
- Do not store the bitumen emulsion below 10 degrees C, as it may break the dispersed structure of bitumen. in such situation bitumen may separate from water, it may be not suitable for further use
- it is not advisable to force air to agitate the emulsion, it may cause the emulsion to break
- Do not use lime or other acidic material with cationic based emulsion.