Bitumen Emulsion
WHAT IS BITUMEN EMULSION ?
Bitumen emulsion is becoming more popular in the pavement construction sector. its applications are quite diverse, including cold recycling mixtures, tack coating, and surface treatment. emulsions are an innovative method for liquifying bitumen by dispersing it in water. Bitumen emulsions have a significant advantage over hot bitumen since their operations need less energy because their viscosity is lower than that of hot bitumen. Furthermore, there are fewer hazards of fire and burns, and the process consumes less energy . As a result, the cold mix emits less ozone-depleting hydrocarbons . As an emulsion, bitumen emulsion is considered as an oil in water (O/W) emulsion system with water (or soap) as the continuous phase and bitumen as the dispersed phase. For phase compatibility, non-ionic, anionic, or cationic surfactants are added at a concentration of 1–2 weight percent of the total bitumen emulsion mass. According to industrial experience , the proper emulsion for road applications has a high bitumen content, which normally ranges from 60 to 70%, with a unimodal droplet size distribution and an average droplet size ranging from 5 to 15 μm. Surfactants lower the viscosity of the system in comparison to the initial viscosity of the bitumen. The amphiphile molecule (surfactant) prevents droplet coalescence by decreasing the interfacial tension between bitumen and water, thereby stabilizing the system and allowing emulsification .
BITUMEN EMULSION FOR ROAD CONSTRUCTION
Today 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.
ADVANTAGE OF EMULSION
- The strength properties of bitumen are preserved in emulsion mixes since emulsions do not need hot mixing. Generally, cold mixing or just slightly warming the ingredients of the emulsion mix are done for the construction of pavements.
- The emulsion can be used in wet weather even when it is raining.
- Emulsions possess anti-stripping properties.
- Emulsions with lower viscosity or thinner consistency improve spreadability and allow better coating of the bitumen on the surface of aggregate.
- There is no wastage during laying and storage.
- Since emulsions are water-based, there is less effect on the environment.
- It is the least energy-intensive of all construction material: there is no need to heat.
USAGE OF WATER BASED BITUMEN EMULTION
Bitu Coat Primer: Combine one volume of this coat with four volumes of water. One litre of Water Based Bitumen Emulsion can prime the area of 450 Sqft.
Bitu Coat Putty: Combine one volume of the offered coat with double volumes of silica flour or quartz powder.
Bitu Coat Mortar: This should be added with three volumes of dry natural sand. One litre of this emulsion can yield two liters of mortar.
Waterproofing brick bat Coba & normal concrete: Clean up the surface in a good manner so that all loose particles can be completely removed. It there is a crack on the surface it should be be suitably widened. Priming of the the widened cracks is needed here. Fill the cracks with the provided emulsion. The product can be applied on the slumps and potholes for the purpose of leveling & filling. Brush apply the emulsion on entire surface with two or three coatings. Give fibre glass of scrim material at places of horizontal & vertical surfaces.
Repairing derelict bituminous felts: Cut to widen the cracks and do away with the de-bonded felt. Fill and prime the cracks with the utilization of the provided Water Based Bitumen Emulsion. Fill the de-bonded cut out orbits with this mortar and then brush apply with the same on the total area with two coatings.
Aluminium /Asbestos /Zinc Sheet roofing: Render scrim or fibre glass material at Bolts and junction of sheet over one coating of this coating and then brush apply with the offered emulsion on the entire surface in two or more than two coats.
Chapped drainage pipes: Brush apply this coat on the cracked pipe. When the first coating is still wet wrap scrim fabric as well as glass around the pipe and then make second coat on the fabric.
Damp proof course: Go for double coats of this coat on the clean plinth. Apply the second coat after four hours of basic coat. When you find the second coat wet and dewy, blind it with the help of clean sharp sand so as to render a mechanical key.
Concealed water as well as drainage pipes: It will be prove to be a good idea, when all drainage pipes as well as concealed water will be treated with this coat. The product will give protection to concrete from the damage grounded by leakages. Utilize one coat of this product on the pipe and wrap it with fiber mesh. Employ the second coat of this emulsion and then back fill.
Subsoil Structures: In majority of the cases, subsoil structures are susceptible to water pressure along with attack of termite chloride and sulphate. Therefore, before the process of back filling all subsoil structures such as footings, basement walls etc should be well coated with double coats of Water Based Bitumen Emulsion.
Anti-termite treatment: Use this as an anti-termite treatment as it works as a highly effectual anti-termite treatment. Most often when customary anti-termite treatments are failed, this emulsion provides permanent anti termite protection.
BITUMEN EMULSION PROPERTIES
The most essential performance requirements of bitumen emulsions are stability, viscosity, breaking, adhesion, droplet size, and dispersion. The perfect emulsion is stable under the conditions of storage, transport, and application, but it should return to bitumen quickly after application, leaving a binder with the properties of the original bitumen, firmly adhering to the aggregate, and consequently providing enough bearing capacity for a timely construction process
BITUMEN EMULSION STABILITY
Emulsion stability is an important parameter to consider and monitor when producing a bitumen emulsion. The tendency of an emulsion to alter characteristics over time is referred to as its emulsion stability . In general, it is controlled by the interactions between the surfactant and the water/bitumen interfaces. During the storage, bitumen droplets begin to approach one another due to low surfactant concentration at the interfaces; therefore, contact between the two droplets is expected, and what is called the flocculation phenomenon occurs . When there is no mechanical agitation in the system, this is what happens during emulsion storage. If steps are not taken to reverse flocculation, coalescence can occur . With coalescence, the surfactant layer between the droplets is compromised, allowing the droplets to contact one another. During this process, water can become trapped within the new larger droplet. Since there is no longer a physical barrier between the emulsion droplets, the droplets cannot be separated . This last mechanism has substantial dependence on formulation in terms of the bitumen grade, bitumen temperature, soap temperature, and surfactant type . During storage, bitumen emulsion is subjected to gravitational force, leading to the bitumen droplets being dragged down to the bottom due to the difference in densities of the disperse and the continuous phases forming the sedimentation phenomenon.
BITUMEN EMULSION VISCOSITY
Emulsion viscosity is an important performance characteristic of bitumen emulsions. In cold recycled mixes, low viscous emulsions may drain off the aggregate or affect the aggregate/binder adhesion evolution, which in turn affects the gaining of the mechanical strength. On the other hand, in chip seal, low viscosity emulsions are likely to run off the road, whereas highly viscous emulsions may not distribute well over the surface. In this manner, bitumen emulsion viscosity affects the performance of the final product. Bitumen emulsion viscosity is affected by factors such as emulsion particle size and particle size distribution , the bitumen to water ratio , the surfactant type , and the presence of salt in the bitumen , which can lead to a higher viscosity during storage of the emulsion .
THE PRODUCTION OF BITUMEN EMULSION TAKES PLACE IN TWO SIMPLE STEPS:
Step 1: 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.
Step 2: 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.
TYPES OF EMULSION
The Bitumen emulsion is classified into two types:
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.
a) 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.
b) 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.
c) 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,
BUTUMEN EMULSION ADHESIVE
Considering the right type of aggregate and Bitumen Emulsion is very important to characterize the compatibility of CRM in terms of adhesion performance and water sensitivity. Therefore, the choice of the surfactant with the type of mineral material can be optimized to achieve the maximum efficiency of preparation and use of the bitumen emulsion. However, the research on the surface characteristics of the aggregate and bitumen emulsion chemistry is rarely reported. Meanwhile, each aggregate-bitumen emulsion combination has a distinct chemical composition, which influences the connection between the aggregate and the bitumen and therefore affects the CRM mechanical performance (i.e., bearing capacity and water damage sensitivity).
In the case of cationic emulsions, the use of an aggregate with a surface charge similar to that of bitumen, such as limestone, results in poor adhesion between the bitumen and the aggregate, as well as a delay in the curing time. This phenomenon, as shown in, is governed by the physiochemical adsorption of the bitumen and surfactant onto the mineral filler/and or aggregate surface, which is in turn controlled by several factors, including Van der Waals attraction forces, electrostatic forces, or covalent and electrovalent bindings, and the film adhesion. The formation of adhesion film depends on the bitumen and aggregate type. In an anionic emulsion, bitumen droplets are surrounded by a negative charge. If the anionic bitumen emulsion is mixed with an acid-nature aggregate (i.e., silica), then emulsion could be destabilized rapidly and therefore cause early adhesion. Recently, a study on molecular dynamic simulation and conductivity experiments was conducted to systematically explore the adsorption of different anionic surfactants on calcium carbonate and silica.
MANUFACTURE OF BITUMEN EMULSION
The production of bitumen emulsion is a complex process. In the industry, formulators must consider several aspects linked not only to the production process but also to the end attributes for which the emulsion has been developed. Mechanical parameters such as the emulsification method and its variables must be managed during the production of a bitumen emulsion. There are two methods used to fabricate bitumen emulsions, namely colloid mill and High Internal Phase Ratio (HIPR). Colloid mill is the most commonly used equipment for emulsion manufacturing. Colloid mill, as illustrated in, consists of a fast rotor (1000–6000 revs/min) in a stator; thanks to the generated shear forces, the bitumen is torn and stretched into globules, which are coated by surfactant and thus electrically charged. The mill’s geometric characteristics are instrumental in the distribution of particle sizes, with a common adjustable clearance range of 0.25 to 0.5 mm between the rotor and stator. The colloid mill receives, firstly, surfactant mixed with water with temperatures ranging from 40–65 °C. Afterward, hot bitumen at 120–180 °C, with a viscosity of about 0.2 Pa s, which is suitable for emulsification, is then provided in the colloid mill gradually. In some cases, emulsions may be thermally unstable or short-lived (i.e., stiffer bitumen or polymer-modified).
