Introduction
Definition of Bitumen Emulsion
Bitumen emulsions are colloidal mixtures of bitumen and water. Due to the different surface tensions of the two liquids, stable emulsions cannot be created simply by mixing. Therefore, various emulsifiers and stabilizers are added. Emulsifiers are amphiphilic molecules that differ in the charge of their polar head group. They reduce the surface tension of the emulsion and thus prevent bitumen particles from fusing.[1]
Composition of Bitumen
An emulsifying agent is used to aid in dispersing the bitumen in water to form a bitumen emulsion. A typical bitumen emulsion is composed of several essential ingredients, each of which affects the performance and characteristics of the emulsion. Based on the table given, the following is a detailed description:
Bitumen
Role: Primary component providing the binding properties.
Details: Viscous road bitumens with penetration are commonly used (25 °C, 0.1 mm) 60–200; it is possible to use bitumen modified by polymers.[2]
Water
Role: Acts as the medium for dispersing bitumen.
Details: The use of hard water and the absence of mechanical impurities are not allowed. A large number of electrolytes can result in decay. Also, decay may occur on the surface of solids. The hardness of used water should not exceed 6 mEq/l.[2]
Emulsifier
Role: Facilitates the dispersion of bitumen in water.
Details: Anionic and cationic emulsifiers. The obtaining of three classes of emulsions - EBC-1,2,3.[2]
Acid
Role: Adjusts the pH and helps in forming the emulsion.
Details: Hydrochloric acid of 25–37%, the pH of the aqueous phase makes 1.5–3.5. It transfers the emulsifier into ionic form, allowing for adjustment of the pH of an aqueous phase and an emulsion.[2]
Solvent
Role: Increases stickiness and aids in film formation and dispersion.
Details: The introduction of a variety of solvents to increase the stickiness emitted during the decay of the bitumen emulsion (as the film-forming agent) and to facilitate its dispersion in water is possible.[2]
Modifier of a Disperse Phase
Role: Enhances the performance of the bitumen.
Details: Polymers may act as a modifier of a dispersed phase. They serve as the polymers that are used for an extended temperature range performance of viscous bitumen with the simultaneous increase of their heat and crack resistance and flexibility.[2]
Stabilizer
Role: Stabilizes the emulsion.
Details: Calcium chloride as 30–35% aqueous solution is often introduced as a stabilizer.[2]
Thinner
Role: Adjust the penetration of the bitumen.
Details: It is used to increase the penetration of bitumen up to the desired value. Vacuum gas oils, oil fractions are used, etc.[2]
Classification of Bitumen Emulsion
Emulsions can also be categorized by the rate at which bitumen droplets coalesce and return to bitumen. This is related to the rate at which the emulsion becomes unstable and breaks after mixing with aggregate and filler. Bitumen emulsions are divided into Rapid-Setting (RS), M-Setting (MS), and Slow-Setting (SS). In addition, bitumen emulsions are classified based on EN 13808, with various letters and numbers indicating viscosity and basic bitumen type. The table shows the abbreviations for cationic emulsions. For example, C69BF3 70/100 is a cationic bitumen emulsion made from 70/100 pen-grade bitumen with a 69% bitumen fraction containing more than 3% (m/m) flux and a breaking class 3.[3]
Cationic emulsion abbreviated description adapted from [3]
Rapid-Setting (RS)
A quick setting emulsified bitumen is used for penetration, surface treatment, tack coating, and mulch treatment.[4] Rapid setting (RS) grade emulsion has been divided into two different grades of emulsions. The nomenclature for the proposed emulsions has been indicated as RS-1 emulsion and RS-2 emulsion.[5]
M-Setting (MS)
A medium setting emulsified bitumen used for plant mixes with coarse aggregate, all of which is retained on a 2.80 mm IS Sieve with practically no material passing 75 microns IS Sieve.[4] M-Setting (MS) grade emulsion has been divided into two different grades of emulsions. The nomenclature for the proposed emulsions has been indicated as MS-1 emulsion and MS-2 emulsion.
Slow-Setting (SS)
A slow-setting emulsified bitumen used for fine aggregate mixes in which a
substantial quantity of aggregate passes a 2.80-mm IS Sieve, and a portion may also pass a 75-micron IS Sieve.[4] Slow setting (SS) emulsion has also been divided into SS-1 and SS-2 emulsion.[5]
Properties of Bitumen Emulsion
Overview of Bitumen Emulsion Properties
Standard bitumen (asphalt) emulsions are brown liquids normally considered to be the oil-in-water (O/W), made by mixing water (25-60%), bitumen (40-75%), emulsifier (0.1-2.5%) and applying mechanical energy sufficient to break the bitumen into droplets.[6]
Classification and Setting Grades
Bitumen emulsion can be classified due to their droplet's charge, pH, and reactivity into cationic (positive charge, acidic), anionic (negative charge, alkaline), and non-ionic types with various setting grades comprising slow setting (SS), medium setting (MS) and rapid setting (RS).[6]
Applications and Performance
Bitumen is not soluble in water so the dispersion of bitumen droplets in water is stabilized using a bitumen emulsifier. Aggregate reactivity is mostly associated with the finest particles, which contribute the greatest to the surface area. Thus, a reactive RS emulsion is used with low-surface-area unreactive aggregates in chip seal applications, whereas a low-reactive SS emulsion is used for a dense cold mix, which has a high content of 75um material, and consequently, a high reactivity.
Specifications for cationic emulsified asphalt slow setting shall conform to the requirements prescribed in Table, according to ASTM D 244 and D 2397. The emulsified asphalt shall be homogeneous after thorough mixing, provided that separation has not occurred owing to freezing. Emulsions separated by freezing shall not be tested. Cationic slow setting (CSS) emulsions are used in combination with aggregates with high surface area to provide the desired coating and curing behavior.[6]
Importance of Stability and Compatibility
In addition, cationic emulsifiers have greater effects on cement hydration compared to anionic emulsifiers because of their compatibility (the addition of alkaline cement to an acidic cationic emulsion causes the pH to increase compared to the emulsion's initial pH) evaluated by emulsion stability. Furthermore, in a mixing application of dense graded aggregates, a lower viscosity of emulsion is usually required.[6]
CSS bitumen emulsion chemistry is such that it enables excellent coating and adhesion of the residual asphalt cement to aggregate surfaces in dense graded mixes because of larger average particle size, which leads to lower emulsion viscosity, as does a broad particle size distribution. In this research, concerning the results of the coating test and cement mixing (ASTM D 244), dense graded aggregate and high adhesion between aggregates particles; a cationic slow setting (CSS-1) asphalt emulsion was chosen.[6]
Properties of Bitumen Emulsion from [6]
Grades of Bitumen Emulsion
The recommended uses of five types of emulsified bitumen of the cationic type suggested in this revision are given below:
Classification Based on Setting Time and Uses
Bitumen emulsions are classified based on how quickly they set or break (i.e., the time it takes for the water to evaporate and the bitumen to coalesce and adhere to the aggregate). The main types are:
Rapid Setting (RS)
RS-1: This type of emulsion breaks quickly upon contact with aggregate. It is typically used in surface treatments like chip sealing, where quick setting is necessary to ensure the aggregate sticks to the bitumen. RS-1 is suitable for use in dry and hot climates.
Uses: Used in surface treatments like chip sealing where quick adhesion is needed to prevent the aggregate from being dislodged by traffic.
RS-2: Similar to RS-1 but with a higher viscosity and slower setting time. It is used in surface dressing and applications where a thicker bitumen film is required.
Uses: Utilized in applications requiring a thicker film of bitumen, such as heavy-duty surface dressing.
Medium Setting (MS)
MS-1: Medium-setting emulsions are designed to mix with coarse aggregates. They are typically used in plant or road mixes where mixing time is short, and an immediate setting is not desired. MS-1 is ideal for cold-mix applications where a stable mix is required before compaction.
Uses: Ideal for cold-mix applications that need to remain stable during mixing and transport. Often used in road bases and patches.
MS-2: Similar to MS-1 but with a slightly different formulation to cater to specific aggregate types or environmental conditions.
Uses: Employed in similar scenarios as MS-1 but optimized for different environmental conditions or aggregate types.
Slow Setting (SS)
SS-1: Slow-setting emulsions are designed for maximum workability and are used where prolonged mixing and setting times are required. They are ideal for tack coats, fog seals, and slurry seals where the emulsion must remain workable for extended periods.
Uses: Used for tack coats, which are applied between layers of asphalt to promote bonding. Also used in fog seals to rejuvenate aged pavements.
SS-2: A variant of SS-1 with higher bitumen content and slightly faster setting time, used in similar applications but where a thicker layer of bitumen is needed.
Uses: Similar to SS-1 but with higher bitumen content for thicker applications, such as in certain types of slurry seals and cold recycling processes.
Classification Based on Viscosity
The viscosity of a bitumen emulsion affects its flow properties and is classified as follows:
Low Viscosity Emulsion
In chip-sealing low viscosity emulsions are likely to run off the road, whereas too-viscous emulsions may not distribute well over the surface. In open-graded emulsion mixes low viscous emulsions may drain off the aggregate. Viscosity is also related to other important properties like settlement - low-viscosity emulsions are liable to settle during storage.[7]
Medium Viscosity Emulsion
These have a balanced flow characteristic, making them suitable for mixing with aggregates in cold mix asphalt and maintenance treatments such as slurry seals.
High Viscosity Emulsion
High-viscosity emulsions are thicker and are used in surface dressing, where a substantial coating of bitumen is required to bind aggregate particles effectively. They provide better resistance to traffic loads and weathering.
Classification Based on Charge
Bitumen emulsions can also be classified based on the type of charge on the bitumen particles:
Cationic Emulsion
These emulsions have positively charged bitumen particles. Cationic emulsions are widely used because they have better adhesion properties with most types of aggregates. They are particularly effective in acidic and neutral aggregates.
Anionic Emulsion
These emulsions have negatively charged bitumen particles. Anionic emulsions are less common but are used in specific situations where the aggregate has a natural affinity for anionic bitumen particles, such as in alkaline aggregates. Nowadays, anionic emulsifiers are mainly derivatives of by-products from the paper or “kraft” pulp industry, i.e. tall oil fatty acids (TOFA), tall oil rosins, and lignin.
Applications of Bitumen Emulsion
Road Construction and Maintenance
Surface Dressing
Definition: The Surface Dressing work consists of the application of an appropriate grade of bitumen/emulsion on a previously prepared base followed by the application of a coat of aggregates as cover material of appropriate size, grading, and well-rolled. Surface Dressing does not enhance the structural strength, nor does it restore the riding quality of a surface having large surface irregularities but it is highly effective in waterproofing the road.[8]
Procedure: The road surface is cleaned and prepared. Bitumen emulsion is then sprayed uniformly, and aggregate is spread over the emulsion. After rolling to embed the aggregate, the road is opened to traffic.
Benefits: This technique is cost-effective and provides a quick method to renew the road surface, offering improved grip and protection against water ingress.
Tack Coats
Definition: Tack Coat is a very light application of low-viscosity liquid bituminous material to an existing bituminous, cement concrete or primed granular surface to ensure a bond between the surface being paved and the overlaying course. The tack coat material is not expected to penetrate the pavement and for this reason; the applications should be very light to provide an adequate bond between the two layers.[9]
Application: The method of application of tack coat will also depend on the type of equipment to be used, size of nozzles, pressure at the spray bar, and speed of the forward movement of the vehicle. A spraying trial shall demonstrate that the equipment and method to be used are capable of providing a uniform spray, within a specified tolerance limit. The quantity of tack coat shall be checked periodically using the tray coating test. The dilution of RS-1 bitumen emulsion is not permitted.[9]
Advantages: Before spreading premixed material, a tack coat should be applied on the prepared/primed surface using a self-propelled or towed pressure sprayer at the specified rate. Hand spraying for small areas inaccessible to the distributor can be done with the approval of the Engineering Charge. The range of spraying temperature for bituminous emulsion shall be 20°C to 70°C. The tack coat shall be left to cure until all the volatiles have evaporated.[9]
Slurry Seals
Definition: A slurry seal is a mixture of aggregates, asphalt emulsion, water, and fillers which are mixed according to a laboratory, design mix formula. A slurry seal is applied to an existing pavement surface using a spreader box linked to the slurry mixing unit. Slurry seal is a well-known surface maintenance method because it is cost-effective, extends the life of pavement, is quickly applied, and improves road handling characteristics.[10]
Process: The slurry mixture is spread over the road using a slurry paver. It fills cracks and provides a new wearing surface.
Advantages: Slurry seals improve surface texture, restore skid resistance, and extend the life of the pavement by sealing small cracks and preventing moisture infiltration.
Waterproofing and Damp Proofing
Foundations and Basements
Application: Bitumen emulsion is applied to the exterior of foundations and basements to prevent water penetration and protect structural integrity.
Process: This emulsion is applied using a brush or sprayer. After drying, it forms a waterproof barrier.
Benefits: This prevents water from entering the structure, reducing the risk of dampness, mould, and structural damage.
Roofs and Terraces
Application: Bitumen emulsions are used to create waterproof membranes on roofs and terraces.
Process: The emulsion is applied in multiple layers, sometimes reinforced with fabric, to produce a durable, waterproof layer.
Advantages: It provides excellent waterproofness, UV resistance, and flexibility to accommodate thermal movements, ensuring long-term protection for roofs and terraces.
Wall Coatings
Application: Bitumen emulsion can provide a waterproof and protective coating on external walls.
Process: Emulsion is applied to the wall surface to create a barrier against moisture.
Benefits: This application prevents water leakage, protects against weathering, and improves the longevity of the wall structure.
Industrial Uses
Pipe Coating
Application: Bitumen emulsion coats pipes and protects them from corrosion and moisture.
Process: The pipes are cleaned, and an emulsion is applied to form a continuous, protective layer.
Advantages: It provides excellent corrosion resistance, increases the life of pipes, and reduces maintenance costs.
Corrosion Protection
Application: Bitumen emulsion protects metal structures and equipment from corrosion.
Process: The emulsion is applied to metal surfaces, forming a barrier against moisture and corrosive elements.
Benefits: It extends the life of metal components, reduces maintenance needs, and offers a cost-effective corrosion protection solution.
Adhesives
Application: Bitumen emulsion serves as a strong adhesive in various industrial applications.
Process: It is applied to surfaces to bond materials, providing a durable and flexible adhesive layer.
Advantages: Bitumen emulsion adhesives offer excellent bonding strength, water resistance, and flexibility, making them suitable for various industrial applications.
Innovative Uses
Emulsion in Cold Mix Technology
Definition: Cold mix asphalt technology uses bitumen emulsions to prepare asphalt mixtures that can be laid without heating.
Application: Cold-mix asphalt is used for patching, resurfacing, and construction of new pavements, especially in areas where hot-mix asphalt plants are not available.
Benefits: This method reduces energy consumption, reduces emissions, and is more flexible in terms of storage and transportation.
Recycling of Old Pavements
Process: Bitumen emulsions are used to recycle old asphalt pavements. The existing pavement is ground, mixed with bitumen emulsion, and then relaid.
Advantages: This recycling process is environmentally friendly, reduces waste, conserves natural resources, and provides a cost-effective solution for pavement rehabilitation.
Usage in Sustainable Construction Practices
Green Construction: Due to its lower environmental impact compared to traditional hot mix asphalt, bitumen emulsions are increasingly used in sustainable construction practices.
Benefits: The use of bitumen emulsions contributes to reducing greenhouse gas emissions, saving energy, and sustainable use of resources. It also supports the use of recycled materials and promotes environmentally friendly construction methods.
How to Buy Bitumen Emulsion
Identifying Your Needs
Determining the Appropriate Grade for Your Project
Project Specifications: Understand the specific needs of your project. Different grades of bitumen emulsion are suitable for different applications, such as tack coat, surface dressing, cold mix, or slurry seal. Consult project engineers or specialists to determine the most appropriate grade.
Performance Requirements: Consider the required performance characteristics, such as setting time, viscosity, and adhesion properties. For example, fast-setting emulsions are ideal for quick traffic conditions, while slow-setting emulsions are better for applications requiring longer working times.
Local Regulations: Make sure the grade chosen complies with local regulations and standards for road construction or maintenance. Regulatory bodies often provide guidelines on acceptable types of bitumen emulsion for various uses.
Considering Environmental and Project-Specific Factors
Climate and Weather Conditions: Take the local climate into account. For example, in areas with high temperatures, it may be beneficial to use an emulsion with a higher viscosity to prevent bleeding, while in colder areas an emulsion with better adhesion properties may be required to prevent cracking.
Traffic Load and Usage: Assess the expected traffic load on the road. High-traffic areas may require a stronger emulsion with greater durability and wear resistance.
Substrate Compatibility: Evaluate the type of substrate and aggregate to ensure compatibility with the selected bitumen emulsion. Some emulsions are specifically designed to work better with certain types of aggregate.
Finding Reliable Suppliers
Researching and Shortlisting Suppliers
Online Research: Start by searching for reputable bitumen emulsion suppliers online. Look for companies with a strong presence in the industry and a positive reputation. Among the top suppliers, Classic Bitumen is one of the largest and most trusted manufacturers and suppliers of bitumen emulsion, known for its high-quality products and extensive industry experience.
Industry Directories: Use industry-specific directories and trade associations to find potential suppliers. These directories often contain lists of certified and reliable suppliers, including industry leaders like Classic Bitumen.
Networking: Attend industry conferences, seminars, and trade shows to network with suppliers and gather recommendations from colleagues and industry experts. Classic Bitumen often participates in these events, providing an opportunity to connect with a leading supplier in the field.
Checking Certifications and Quality Standards
ISO Certifications: Look for suppliers that have ISO certifications, which indicate compliance with international quality management standards.
Product Standards: Ensure that the supplier's products meet relevant national and international standards, such as ASTM or EN standards for bitumen emulsions.
Third-Party Testing: Prefer suppliers whose products have been tested and certified by independent third-party laboratories for quality and performance.
Reading Reviews and Seeking Recommendations
Customer Reviews: Read customer reviews and testimonials on the supplier's website and third-party review sites to assess customer satisfaction and product reliability.
Professional Recommendations: Ask for recommendations from industry professionals, contractors, and engineers who have used the supplier's products before.
Case Studies and References: Request case studies and references from the supplier to see examples of their products in similar projects.
Requesting Quotes and Samples
Contacting Suppliers for Quotes
Detailed Requirements: Provide detailed information about your project requirements, including the type of emulsion, quantity, delivery schedule, and specific performance characteristics required.
Multiple Quotes: Contact several suppliers to get quotations. This will help you compare prices, terms, and services offered.
Requesting and Testing Samples for Quality Assurance
Sample Request: Ask for samples of bitumen emulsion before buying in bulk. Make sure the samples represent the product you will receive.
Laboratory Testing: Perform laboratory tests on the samples to verify their properties, such as viscosity, setting time, and adhesion.
Field Trials: Conducting small-scale field trials using samples to assess their performance under real-world conditions.
Placing an Order
Negotiating Terms and Conditions
Pricing and Discounts: Negotiate pricing, especially for large orders. Inquire about bulk discounts and long-term contract pricing.
Payment Terms: Discuss payment terms, including advance payments, credit terms, and payment schedules.
Delivery and Logistics: Clarify delivery terms, including delivery schedules, transportation costs, and shipping and handling responsibilities.
Warranties and Guarantees: Make sure the supplier offers a warranty or guarantee for its products, covering aspects such as product quality and performance.
Finalizing the Purchase and Delivery Details
Purchase Order: Issue a formal purchase order detailing the agreed terms, including product specifications, quantities, prices, delivery dates, and payment terms.
Contract Agreement: Sign a contract with the supplier, outlining all agreed terms and conditions to ensure security and clarity for both parties.
Delivery Coordination: Coordinate with the supplier and your logistics team to ensure timely and smooth delivery of bitumen emulsion. Prepare for receipt and storage of the product to maintain its quality.
Buy Price of Bitumen Emulsion
Factors Influencing Price
Quality and Grade of the Emulsion
Grade Specifications: Different grades of bitumen emulsion (rapid setting, medium setting, slow setting) have varying production processes and raw material requirements, impacting their prices. Higher-quality emulsions designed for specific applications or extreme conditions typically cost more.
Performance Additives: Emulsions with added polymers or other performance-enhancing additives are more expensive due to the higher costs of these materials.
Consistency and Stability: Emulsions that offer superior stability and consistent performance under varying conditions may command a premium price due to the more stringent manufacturing controls and higher-quality ingredients used.
Supplier and Brand Reputation
Established Brands: Suppliers with a strong market presence and reputation for quality may charge higher prices due to their proven track record and customer trust.
Certifications and Accreditations: Suppliers with industry certifications (e.g., ISO, ASTM) may offer higher-priced products reflecting their commitment to quality and compliance with international standards.
Customer Service and Support: Suppliers known for excellent customer service, technical support, and after-sales service might price their products higher, offering additional value beyond just the product.
Quantity and Order Size
Bulk Orders: Larger orders typically attract volume discounts, reducing the per-unit cost of bitumen emulsion. Suppliers often offer tiered pricing, with significant savings for bulk purchases.
Small Orders: Smaller orders may not benefit from discounts and could incur higher per-unit costs due to the fixed costs associated with production and transportation being spread over fewer units.
Regional and Global Market Trends
Crude Oil Prices: Since bitumen is a byproduct of crude oil refining, fluctuations in crude oil prices directly impact bitumen emulsion prices. Higher oil prices generally lead to higher bitumen costs.
Supply and Demand Dynamics: Regional demand for construction materials, seasonal variations, and the availability of raw materials can influence prices. For example, increased construction activity in summer months might drive up prices due to higher demand.
Geopolitical Factors: Political stability in oil-producing regions, trade policies, and tariffs can affect the availability and cost of bitumen emulsions.
Current Market Prices
Overview of Typical Price Ranges
Price per Ton: The cost of bitumen emulsion is typically quoted per ton. Prices can vary widely based on grade and supplier but generally range from $300 to $600 per ton for standard emulsions.
Premium Grades: Specialty emulsions with performance additives or those designed for specific applications can exceed $700 per ton.
Comparison of Prices from Different Suppliers
Price Lists and Quotes: Get price lists from several suppliers to compare rates. Make sure you compare the same grades and quality levels to make an accurate assessment.
Included Services: Consider what services are included in the price, such as delivery, technical support and warranty. A slightly higher price from a reputable supplier may offer better value if it includes comprehensive support and quality assurance.
Cost-Saving Tips
Bulk Purchasing
Volume Discounts: Negotiate volume discounts with suppliers for large orders. Suppliers are often willing to significantly reduce the per-unit price for bulk purchases because of economies of scale.
Storage Considerations: Make sure you have adequate storage facilities to handle bulk deliveries without compromising on the quality of the emulsion.
Long-Term Contracts with Suppliers
Fixed Pricing: Enter into long-term contracts with suppliers to keep prices stable and avoid market fluctuations. This can provide cost stability for extended projects.
Preferred Customer Benefits: Long-term relationships can lead to preferred customer status, as well as access to better terms, priority delivery, and additional services.
Seasonal Discounts and Promotions
Off-Season Purchasing: Prices may be lower during off-peak seasons when demand for building materials is lower. Plan your purchases to take advantage of these lower prices.
Promotions and Offers: Suppliers often run promotions or offer discounts at trade shows, industry events, or at the end of the fiscal year. Keep an eye out for these opportunities to save costs.
Future Trends of Bitumen Emulsion
The global bitumen emulsifier market is expected to witness significant growth, driven by rising demand from the road construction sector and the shift towards environmentally friendly products. With a projected CAGR of 5.3% from 2024 to 2032, the market is expected to grow from USD 59.70 million in 2024 to USD 90.24 million by 2032.[11]
The Asia Pacific region, which holds a major market share in 2023, is expected to continue its growth momentum owing to rapid urbanization and government initiatives in infrastructure development. Meanwhile, Europe and North America are also projected to experience substantial growth driven by rising awareness about environmental sustainability and the adoption of eco-friendly emulsifiers.[11]
However, challenges such as the toxicity of some bitumen emulsifiers may hinder market growth. Despite this, the ongoing trend of developing bio-based and sustainable emulsifiers presents significant opportunities for innovation and market expansion.[11]
The market remains competitive, with key players such as Arkema, Evonik, and Croda International maintaining an edge through strategic alliances and product innovations. The industry's focus on research and development of environmentally friendly resins and bio-bitumen is set to drive the market further, making it a vital component of global construction and infrastructure projects in the coming years.[11]
Conclusion
Bitumen emulsion is a highly versatile and environmentally friendly material used in a variety of road construction and maintenance applications. Its ability to be applied at low temperatures, reduce energy consumption and minimize environmental impact makes it an ideal choice for developing sustainable infrastructure. By understanding the properties, types and applications of bitumen emulsion, construction industry professionals can leverage its benefits to achieve sustainable and cost-effective results.
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