Rumays Intl. Trading Co.
What Is Emulsion Bitumen?
Holding a share of 20% global bitumen use, Emulsion Bitumen (Water bitumen) is obtained by mixing bitumen and water with an emulsifier. It’s basically an O/W (Oil on Water solution) a dispersion of bitumen particles on water, stabilized with the addiction of surfactants (Surface active agents) or most commonly known as emulsifiers, that will permit the bitumen to de-diluted in water. The amount of emulsifier is very small and is about 0.3 to 0.5% by weight of bitumen.
Bitumen emulsion consists of three basic ingredients: bitumen, water, and an emulsifying agent. Based on specifications it may contain other additives, such as stabilizers, coating improvers, anti-strips, or break control agents. It is well known that water and asphalt will not mix, except under carefully controlled conditions using highly specialized equipment and chemical additives.
An emulsifier with a long hydrocarbon chain and either a cationic or anionic ending is employed as a surface active agent should be mixed with water before adding asphaltum because asphaltum is an oil and cannot be combined with water. The addition of an emulsifier to water facilitates in the breakdown of asphalt into minute particles and maintains it disseminated in suspension. An electrochemical environment is provided by this emulsifier. The ionic part of the chain is drawn to water, whereas the hydrocarbon part is attracted to bitumen. As a result, bitumen emulsion is a liquid product composed of three components (water + emulsion + asphaltum) in which droplets of asphaltum are suspended in water.
In this way, the bitumen particles repel each other due to the induced load and float in water in the form of spheres with a diameter of one hundredth to one thousandth of a millimeter. An emulsion is a stable mixture of extremely small particles of one liquid dispersed (spread) in another liquid in which it does not dissolve. An emulsion can be created by using an emulsifier or emulsifier agent which soap-like substance is used to coat each individual particle of another substance and so prevent these particles from sticking together.
The emulsions can be cationic (positive charge) or anionic (negatively charged). The globules of the same charge hence repel each other, making the whole system stable. To facilitate adhesion with the aggregates (that are negatively charged), cationic emulsions are more preferred.
Based on Setting Time:
⦁ Slow setting emulsion
⦁ Medium setting emulsion
⦁ Rapid setting emulsion
Based on Surface Charge:
⦁ Anionic Bitumen Emulsion
⦁ Cationic Bitumen Emulsion
1. Based on Setting Time: When the bitumen emulsion is applied on the aggregate for the road works the water evaporates leaving behind the bitumen droplets. These droplets spread on the aggregate and bind with each other and gains strength eventually. Based upon the time taken by the vitamin emulsion to evaporate the water and between particles to separate from water, bitumen emulsion is further classified into 3 types based on setting time:
⦁ Slow setting emulsion
In this type of emulsion, a special type of emulsifier is used to slow the process of water evaporation. This type of emulsifier are relatively stable.
⦁ Medium setting emulsion
This type of bitumen emulsion doesn’t break as when applied on aggregate. The process of evaporation starts when the fine dust of mineral are mixed with the aggregate emulsion mix.
⦁ Rapid setting emulsion
This type of bitumen emulsion breaks down rapidly as it comes with contact with aggregate helping in fast setting and rapid curing.
2. Based on Surface Charge
Based upon the type of surface charge, they are divided into 2 types,
⦁ Anionic Bitumen Emulsion
⦁ Cationic Bitumen Emulsion
Anionic Type: In which the bitumen particles are negatively charged and the emulsifier is fatty acid metallic soap. These suitable for use with calcareous aggregates like limestone. Most often, fatty acid and resin acid alkaline salts are used. They are obtained by saponification of the liquid resin, called Tall-Oil. This substance is a residual, distilled substance, a by-product of the paper pulp industry from resinous wood treated using the “sulfate” process.
Cationic type: When the emulsion is being produced the cations are adsorbed by asphaltum droplets, negatively ions remain in the water. In which the bitumen particles are positively charged and the emulsifier used is a long chain amine. These are suitable for use with siliceous aggregates like quartzite, sandstone, granite etc. The undeniably most complete field of use is represented by the rapid setting emulsions.
Bitumen emulsions are divided into three categories:
⦁ Anionic with negatively charged globules
⦁ Cationic with positively charged globules
⦁ Non-ionic with neutral globules.
In anionic bitumen emulsion, the tiny droplets of bitumen are electronegative recharged. In Cationic bitumen emulsion the tiny droplets of bitumen are electro positively charged. The average and commonly used between emulsions is cationic between emulsions. Selection of positive or negative recharge between emulsions depends upon the mineral composition of aggregate on which it is used Ex: In case of silica rich aggregates the surface of silica is aggregate is positively charged therefore cationic bitumen emulsion is used which helps in better spreading and binding of bitumen with aggregates.
The coating of the bitumen particles by the emulsifier gives them an electrostatic charge. Depending on the type of emulsifier, this can generally be either negative or positive. The interaction of the charged particles is the reason it is possible to make emulsions that do not rapidly revert to the separate phases.
Emulsions in which the bitumen droplets are negatively charged are called anionic emulsions. Emulsions in which the particles are positively charged are called cationic emulsions.
To ensure that an emulsion remains either anionic or cationic, its pH (that is the balance of acids and bases) is controlled so that typically an anionic emulsion has an alkaline pH of over 7 and a cationic emulsion has an acidic pH of below 7.
This fundamental property of both anionic and cationic emulsions requires that they never be mixed. Mixing of an anionic emulsion and a cationic emulsion allows the negatively charged anionic droplets and the positively charged cationic particles to come together through electrical attraction. Ultimately enough droplets will combine and the bitumen will separate out, becoming unusable and destroying the emulsion.
Bitumen emulsions are classified based on how quickly they set, along with their electrical charge. Based on the precise mix of ingredients, an emulsion bitumen may be designed to be rapid-setting (RS), medium-setting (MS), or slow-setting (SS). Cationic emulsions are designated with a letter C in front of the emulsion grade, while anionic emulsions are not given an extra letter.
The characteristics of an emulsion are designated by the terms rapid (R), medium (M) and slow (S). The main grades for bitumen emulsions are classified as follows:
Emulsion Bitumen Grades:
A suffix of “h” or “s” at the end of the emulsion grade indicates that a hard or soft base asphalt was used. Some anionic emulsions are designated “HF” for “high float,” which indicates that chemicals were used to give the asphalt a thicker film. When applied to an aggregate surface, this helps more of the asphalt film stay in place on the aggregate particles without draining into the pavement structure.
Manufacture of Bitumen Emulsion
The production of bitumen emulsion takes place in two simple steps:
Firstly, the water is mixed with the appropriate emulsifier and other chemical agents. The choice of emulsifier depends upon its ionic nature of the mix.
Now water emulsifier mix is added with bitumen in a colloidal mill. The amount of bituminous to be added depends upon the nature of use of bitumen emulsion. If it is used for important works then between percent can range up to 60 to 70%. The average range of bitumen mixed is from 40 to 70%. The colloidal mill breaks down the bitumen into very tiny droplets. Average size of bitumen droplet is about 2 Micron. But the droplets try to join them self with each other and make it settle down. But the emulsifier added creates a coating of surface charge around every drop droplet of the bitumen that helps to keep away from each other on the other hand it is also it also keeps the droplet in dispersed and suspended form. The mix received from the colloidal mill is stored in the storage tanks and used as per requirement.
As Bitumen emulsions behave more like water than bitumen; they can be used at much lower temperatures than bitumen, quite often at ambient temperature, and can be readily mixed with water. Bitumen emulsions are much less sensitive to problems caused by damp or dusty aggregate and cool conditions due to their water base. Anionic emulsions are best used with positively charged aggregate surfaces such as basalt, dolomite and limestone, whereas cationic emulsions are preferred for use with negatively charged silicious aggregates such as quartz, granite, sandstone and river gravel. In general, cationic emulsions can be used with a wider range of aggregates, will tolerate greater quantities of moisture, and will break at a lower ambient temperature.
Bitumen emulsions provide a range of benefits to other forms. Emulsifying bitumen allows you to reduce the viscosity without the need to continuously heat the product. Bitumen emulsions are particularly useful when it is difficult to use bulky machinery in remote or hard to reach areas, such as rural locations or confined spaces. As there is no need to heat the emulsified product, customers can also make huge savings on energy costs. Bitumen emulsions are perfect for spraying applications, and ideal for pavement maintenance, road rehabilitation processes such as tack coats, chip seals, slurry seals, and micro surfacing.
Bitumen emulsion are used extensively in bituminous road construction. Other than this they are used for maintenance and repair work.
⦁ Road Construction
The main use of bitumen is in the road making industry for construction and maintenance. Bitumen emulsions are a dispersion of bitumen in an aqueous continuous phase, stabilized by the addition of an emulsifier. They are prepared as emulsions at high temperatures but applied as solid dispersions at ambient temperatures. In road making, bitumen products are typically applied with mineral aggregate. The strong adhesion that occurs between the bitumen and mineral aggregate enables the bitumen to act as a binder, with the mineral aggregate providing mechanical strength for the road. Bitumen is difficult to work with, at ambient temperatures, since it is a highly viscous material under these conditions. It can, however, be transformed into a workable state by blending with petroleum solvents or by emulsification with a surfactant in water to form a bitumen emulsion. Emulsified bitumen acts as a key tool in road maintenance and construction technology as it combines amazing versatility while offering multiple comparative advantages.
⦁ Surface Dressing
Surface Dressing is a method of resurfacing an existing road by binding a new layer of stone chippings to the road surface with bitumen. The process is not designed to reprofile the road, or to provide it with additional strength. Surface Dressing is a highly efficient and cost effective way of restoring a road’s grip characteristics while sealing cracks to prevent water penetrating and damaging the lower layers and foundation. The main type of Surface Dressing binder is bitumen emulsion.
⦁ Cold Mixes
Cold mix asphalt is produced when a special type of emulsified bitumen is mixed with aggregates. The emulsion used reduces the viscosity of the asphalt, making it pliable even at cold temperatures. Cold mix asphalt can be premixed and stored for months at a time, making it ideal for road repairs and other low-volume uses. Cold mix asphalt also has a number of environmental benefits. Low-temperature mixing reduces fuel consumption and resulting fumes. Production of cold mix asphalt doesn’t require high temperatures, therefore, emissions from the production facility are also reduced.
⦁ Tack Coat
Tack coat (also known as bond coat) is the most common application for bitumen emulsion. A thin emulsion layer is applied by spraying it to ensure secure adhesion of the asphalt mix to the underlying layers. This layer is required for most roads. Adequate bonding between constructions lifts and especially between the existing road surface and an overlay is critical in order for the completed pavement structure to behave as a single unit and provide adequate strength. If adjacent layers do not bond to one another they essentially behave as multiple independent thin layers – none of which are designed to accommodate the anticipated traffic-imposed bending stresses. Inadequate bonding between layers can result in delamination (debonding) followed by longitudinal wheel path cracking, fatigue cracking, potholes, and other distresses such as rutting that greatly reduce pavement life.
Heavier applications may be used under porous layers or around patches where it also functions as a seal coat. Without tack coat, the asphalt layers in a roadway may separate which reduces the structural integrity of the road and may also allow water to penetrate the structure.
⦁ Prime Coat
Prime coats protect the integrity of the granular base during construction and help reduce dust. In the case of a base that is to be covered with a thin hot mix layer or a chip seal for a low volume roadway, priming ensures a good bond between the seal and the underlying surface which otherwise would have a tendency to delaminate.
⦁ Surface Treatment
The surface treatment is used in laying of new asphalt coats, recycled asphalt coats, and for better traction of vehicle wheels with the road surface and to increase road lifetime. The surface coating makes the road top waterproof, texturized, dense, and wear-resistant. They are primarily used for tack coats that use in between hot mix asphalt layers and prime coats for thin hot mix surfacing layers or a chip seal pavements.
⦁ Slurry Seal
Slurry shall consist of mixture of approved bitumen-emulsion, fine mineral aggregate, filler, water and specified additives, proportioned, mixed and uniformly spread over properly prepared surface. The completed slurry seal shall leave a homogeneous material, adhere firmly to the prepared surface, and have friction-resistant surface texture throughout its service life. Exact composition of slurry mixture shall be determined by the laboratory tests. The application of slurry seal will significantly extend the life of existing pavements by protecting the under-surface from effects of aging and the environment, filling smaller cracks, preventing of evolving of new cracks. It improves also the surface performance, friction resistance and aesthetic values of pavement. Slurry seal technology can be applied on highways, streets and parking lots, squares etc.
⦁ Emulsions are used in bituminous road construction work. They are especially helpful for maintenance and patch repair works.
⦁ Emulsion can be used in wet weather even when it is raining.
⦁ Use of emulsion bitumen in agricultural lands is to prevent water evaporation and reduce soil moisture.
⦁ Emulsions have been used in soil stabilization, particularly for stabilization of sands in desert areas.
⦁ A rapid setting type emulsion is suitable for surface dressing and penetration macadam type of construction.
⦁ Medium setting type is used for premixing with coarse aggregates.
⦁ In case of fine aggregates, the surface area of aggregate is more and as a result long duration of time is required to mix the emulsion.
⦁ Therefore slow setting emulsion is preferred which gives sufficient time for uniform blending of the mix.
⦁ Rapid setting type of emulsion are used in surface of roads.
⦁ Medium setting type of emulsion are used in premixing of bitumen emulsion and coarse aggregate.
⦁ Slow setting type of emulsion are used with fine aggregates as the surface area is large and requires time for uniform mixing.
⦁ Rapid Setting (RS-1): It is Recommended for tack coat applications
⦁ Rapid Setting (RS-2): It is recommended for surface dressing, grouting
⦁ Medium Setting (MS): It is used for repair work/ surface dressing/ penetration macadam
⦁ Slow Setting (SS-1): It is used for Prime Coat. Crack sealing and fog seal.
⦁ Slow Setting (SS-2): It is used for the slurry seal, road mixes and for prime coat applications.
Advantages of Emulsion Bitumen
⦁ It can be used in damp environment on wet aggregates
⦁ Road repair work can be carried out in minimum time
⦁ Provides better tack coat with better workable conditions
⦁ Can be used in any season except in excessively cold environment or during rainfall
⦁ Long storage stability in clean containers/Tanks
⦁ Choice of viscosity for different applications.
⦁ Bitumen emulation is ecofriendly as it is water based
⦁ Bitumen emulation is used in soil stabilization in desert areas.
⦁ It doesn’t need extra heat while placing
⦁ There is no wastage in placing and laying of bitumen
⦁ Bitumen emulation has anti-stripping properties
⦁ Emulsion Bitumen can be used in wet weather even if it is raining
⦁ The use of this type of bitumen reduces environmental pollution and because no oil or flammable solvents are used, the risk of ignition during bitumen transportation is reduced.
Limitations of Emulsion Bitumen
Even though cationic bitumen emulsions have many advantages over cut-back binders, they also have certain disadvantages:
⦁ Climatic – A regular water supply is required and this can be a great problem in very hot countries, where water can be in very short supply. Also aggregates in arid regions are often very dry and cationic emulsions work most effectively, especially mixing with moist aggregate.
⦁ Stability Emulsions are inherently unstable with limited shortage life, (generally maximum 6 to 12 months).
⦁ Plant Emulsion manufacture requires specialized plant and quality control procedures.
⦁ Bitumen Special emulsifier grade binders are needed to make the best quality emulsions.
⦁ Storage time of bitumen emulsion ranges from few days to 6 months depending upon the percentage of ⦁ Bitumen added while production.
⦁ Setting time may vary due to temperature, wind and type of emulsion.
⦁ Not a single type of bitumen emulsion can be used for all works it depends upon the aggregate type setting time nature of work etc.
⦁ Drum 208 litr (0.8 mm Thickness )
Standard Seaworthy Exportable Packing in200 Kg Reconditioned Drums
Palletizing is required for Cutback Bitumen & Emulsions -200kg drums shall be secured as 4 drums per pallet