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Bitumen Emulsion Production Technology. Emulsion facilities consist of energy, process and auxiliary equipment required for emulsion production. Depending on the objectives, the facilities may be stationary or temporary.

The main feature of stationary facilities is the capability to serve several automobile roads within a region. Emulsion from such facilities is delivered to customers by automobile sprayers, tankers or by railroad.

Emulsion facilities usually include:

• means of raw material acceptance and storage;
• heating sources to maintain raw material temperature;
• piping systems and pumps;
• bitumen-emulsion plants;
• emulsion storage tanks;
• means of emulsion output to tankers;
• weighing scales;
• facility controls and quality control equipment.

Bitumen emulsion production technology

Bitumen emulsion is a dispersed system of bitumen and water. Bitumen is dispersed in water by special devices, known as dispersers (homogenizers). Bitumen emulsions are usually made using a colloid mill, although other dispersion  devices are possible.

Emulsification involves the break-up of the bitumen into droplets. This process is opposed by the internal cohesion and viscosity of the bitumen and the surface tension which resists the creation of new interface.

First, bitumen is pulverized into small droplets.  Droplets also have a tendency to coalesce (rejoin). To achieve a small particle size in the emulsion, it is necessary not only to apply mechanical energy in the right way in order to create small drops, but also to prevent their coalescence once formed. Under the forces is the stream, the large spherical droplets become cylindrical. There are critical ratios of length to diameter, when the droplets break into a smaller and a larger droplets. The process is cyclic and can continue until larger droplets are as small as the smaller ones, that is, 0.01 micron.

To prevent bitumen droplets coagulation, an emulsifier is used. It is a surfactant, concentrated in the phase boundary between water and bitumen.

Emulsifier molecules become a protective layer which prevents adhesion of bitumen droplets. This layer may also include water molecules.

 Cationic Bitumen Emulsion Production Technology  includes the following consecutive stages:

• preparation of bitumen, including its delivery from storage, heating to the required temperature and, if necessary, dehydration;
• production of emulsifier water solution;
• production of bitumen emulsion by mixing emulsifier solution and bitumen;
• storage of the product and offloading into tanks.

Another important thing to ensure  in Bitumen Emulsion Production Technology is generation of enough heat to heat and maintain the temperature of bitumen emulsion components.

The term ‘asphalt emulsion’ was coined in 1890, when this material was first patented. However, asphalt emulsions found no practical use for the next 30 years.

The French scientists were the first to develop methods of emulsion production and application. It was them, who first used “emulsified and saponified” heavy oil fractions in ammonia water. A year later, to prevent accidents due to the clouds of dust created by automobiles during racing, “emulsified oil” was used. By 1904, tar layers covered 360000 m2 of surfaces in France

Another important event occurred on 9 May 1922 in the UK. Hugh Alan MacKay, a chemist, registered a bitumen emulsion patent which changed the technology of road construction in several years. Starting in 1923, the first hundred tons of the new material has been sold quite rapidly. In a year, consumption reached 2500 tons, rising to 6000 tons another year later. At the same time, emulsion production developed in other countries: Denmark, Germany, Australia and India. Total production of emulsion in these countries and the UK reached 150000 tons by the end of 1926.

In the 1930s, of German street was covered with a material later known as thin-film. It consisted of many pulverized additives, water and asphalt. The Kemna company, specialized in the production of advanced asphalt emulsions, opened new markets in many countries of Europe, Asia and Africa.

The next step was the emergence of cationic emulsion in 1951. Due to their properties, they quickly pushed anionic emulsion from the market. In ten years the share of cationic emulsion produced grew to 50%, reaching 92% by 1971.

In 2002 a book was published in France, telling of the latest achievements of science in the production of asphalt emulsions, production processes and the ability to adjust their properties.

Despite being a complex material, the advantages of emulsion compared to hot asphalt are obvious. These are, first and foremost, the following:

• low viscosity, making the material easily permeate small pores;
• high adhesion;
• ability to continue construction and repairs at low temperatures and high humidity;
• improved dosage of the binding material and distribution in a thinner layer;
• fuel economy, since there is no need to heat mineral materials;
• reduced harmful emissions.

Besides, the decisive influence on the quality asphalt emulsions is made by the process equipment. GlobeCore offer the UBV-1 type plants to produce asphalt emulsion at the rate of 1 to 20 m3/hour.

These plants produce anionic or cationic asphalt emulsions fully compliant with the international standards in road construction

Bitumen is primarily obtained by vacuum distillation of carefully selected crude oil or blends of crude oil. It comprises the non-distillable fraction? oftentechnically reffered to as vacuum residue. In its simplest form bitumen production processes separated the lighter, low bololing pointfractions from cruide oil resulting in product with high bolling point, high molecular weight with very low volatility. Properties  and quality of  bitumen depend mainly  on the crude oil (s) used in its manufacture. It is produced to grade specification ither directly by renining or by blending. Bitumen can be further processed to after its physical properties in order meet certain specifications.  Experience of the world bitumen production industry shows that the following processes are viable for bitumen production:

• concentration of oil residue for vacuum distillation. Inert gas or steam are used in the process. Atmospheric distillation is used for production of residual bitumen from asphalt-resinous oil;
• oxidation of various oil residue with air oxygen at 180-300ºС. Such residue can include flux oil, tar, oil pitch, deasphalting asphalts, cracking residue etc;
• desaphalting of oil tar with selective solvents;
• mixing (compounding) of oil residue with distillates, as well as oxidized or residual bitumens.

In practice, the methods above can also be combined.

The most common raw material for bitumen production is oil tar or deasphalting asphalts (asphalt and resinous substances). In some literature they are referred to as “deposited bitumens”. It should be noted that sometimes extracts of selective oil refining, thermal cracking residue or pyrolysis resins can be used for bitumen production.

Production of highly plastic bitumen with good thermal stability and binding properties, raw materials of consistent composition and quality is required.

Usually, heavy oil tar with high resin and asphalt content has the required properties. In the general case, the following is true: the higher the “asphaltene:resin” ratio, the better the structure and properties of bitumen produced. In heavy crude, this ratio is 1.0-1.3.

In countries with short supply of such oil, regular crude is used, which makes the product properties fall short of the quality standards.

Production of residual asphalt is one of the most simple and economic technology. To determine if a specific type of crude oil can be used for residual asphalt production, the yield of the material with penetration 100 by 0.1 mm at 25ºС must be assessed.

Residual asphalt production is economically viable if product yield is 10-20%. Vacuum distillation materials, which consist of organic and heterogenic compounds, most often oil pitch, are used to make such asphalt.

The quality of residual asphalt can be adjusted by changing the modes of the vacuum tower. Vacuum depth influence in the active tower zone, as well as presence of contact devices with low hydraulic resistance, which provide pressure difference across the tower no more than 15-20 mm. hg, influence the process efficiency the most. The pressure at the top of the tower is maintained at 20 mm. hg or less.

Residual asphalt production is characterized by a significant reduction of paraffin naphthenic hydrocarbons due to their higher volatility compared to similar substances of the same group. Superheated steam is required to reduce the amount of paraffin naphthenic hydrocarbons in the asphalt and to reduce the temperature of residue distillation. This results in residual asphalt with high melting point. But this approach has certain limitations, such as additional costs and the corrosion of metals of which the equipment is made. This lead to emergence of an alternative method, the so called “dry” oil pitch distillation, which requires highly efficient vacuum systems. In general, vacuum technologies are quite promising in the production of residual asphalt, as they allow better oil refining.

One possible raw material for residual asphalt production is highly resinous sour crude with high asphalt and resin content.

It is very important to distillate fractions used for motor fuel production in the beginning of vacuum distillation. The byproduct of this process is tar which can then be used in production of asphalt.

The residual asphalt production process makes it difficult to produce high melting point asphalt, which is a significant limitation.

Petroleum Bitumen is one of the major outputs of oil refining. According to the historical  mention Petroleum, in various forms, is not a recent discovered.   Petroleum (crude oil; conventional petroleum) is found in the microscopic pores of sedimentary rocks such as sandstone and limestone. Not all of the pores in a rock contain petroleum and some pores will be filled with water
or brine that is saturated with minerals.

Petroleum is a naturally occurring mixture of hydrocarbons, generally in a liquid state, which may also include compounds of sulfur nitrogen oxygen metals and other elements. Thus, petroleum and the equivalent term crude oil, cover a wide assortment of materials consisting of mixtures of hydrocarbons and other compounds containing variable amounts of sulfur, nitrogen, and oxygen, which may vary widely in specific gravity, API gravity, the amount of residuum, as well as the variation in properties.

The molecular boundaries of petroleum cover a wide range of boiling points and carbon numbers of hydrocarbon compounds and other compounds containing nitrogen, oxygen, and sulfur, as well as metal-containing (porphyrin) constituents. However, the actual boundaries of such a petroleum map can only be arbitrarily defined in terms of boiling point and carbon number. In fact, petroleum is so diverse that materials from different sources exhibit different boundary limits, and for this reason alone it is not surprising that petroleum has been difficult to map in a precise manner. Since there is a wide variation in the properties of crude petroleum, the proportions in which the different constituents occur vary with the origin and the relative amounts of the source materials that form the initial protopetroleum, as well as the maturation conditions. Thus, some crude oils have higher proportions of the lower boiling components and others (such as heavy oil and bitumen) have higher proportions of higher boiling components (asphaltic components and residuum).

Petroleum Bitumen has many uses: repairs of roads and airfields, road construction, civil and industrial construction (roofing materials, piping production, production of paint etc). Of the above, road construction is where bitumen is used most extensively.

The cover of roads and airfields made with this binding material are stronger and safer, as well as 2 to 2.5 times less expensive than similar layers made of bitumen.

The following types of bitumen are available:

• construction;
• viscous road construction;
• roofing;
• insulation;
• special purpose.

To use oil as a material for bitumen production, it must contain a certain composition of resins, paraffins and asphaltenes. The deposits of such oil are not unlimited, which prompts the use of other types of oil. This, in many cases, reduces the quality of the binding material.

Durability of road layers is mostly defined by the quality of bitumen. Therefore, the materials used for road construction, must meet certain requirements:

• good adhesion to the mineral filler surface;
• wide plasticity range;
• improved low temperature performance.

Using low quality bitumen in road construction leads to premature wear of the road top layer, increasing the costs of repairs. Beside, durability of automobile roads is reduced in 2-2.5 times.

At present, bitumen emulsion found a multitude of uses in road construction: gravel coats, gravel roads, asphalt road top and binding of dust on dirt roads.

At the same time, this construction material can be used in some other road construction applications, such as:

• patch repairs;
• preparation of cold storage mixes;
• surface treatment;
• thin protective layers;
• cold emulsion-mineral mixes;
• tack coats.

Bitumen emulsion applications are not limited to road construction and repairs. This material is also used for other things: ground permeation, protection of concrete structures, coating of metal surfaces, electro and heat insulation materials, production of waterproof cardboard, sand grouting, soil insulation and waterproofing etc.

The reason bitumen emulsion has become so popular is that the bitumen in the emulsion does not have to be hot, giving it a significant advantage over materials requiring heating.

Experience shows that bitumen emulsion are used to best results in cold road construction and repair processes.

Tack coat

Tack 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. There are several types of tack coats. For instance, slow breaking emulsion with 55-60% bitumen can be applied. Based on the properties of the underlying layer, the amount of applied material is determined; this can vary from 0.4 to 1.4 liters per m2.

Surface treatment

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 life time. The surface coating makes the road top waterproof, texturized, dense and wear-resistant.

Gravel impregnation

To make multilayer surfaces with gravel of various sizes, it must be compacted and impregnated with a slow settling emulsion with bitumen content of 50-65%.

Patch repairs

As was mentioned above, application of bitumen emulsions compared to hot bitumen has several advantages. One of such advantages is the capability of application from early spring until late autumn, in temperatures as low as 5ºС. Using emulsion also allows the use of moist materials. When making patch repairs, the application rate is 1.3 – 1.6 liters per square meter of each centimeter of the patch depth.

Bitumen emulsion can also be used to repair cracks in the surface. The material is mixed with fine sand, cracks are filled with this material, several millimeters short of the surface. The mix solidifies, then the remaining millimeters are filled with straight emulsion. Sand is applied to the surface to prevent the patch from being damaged.

Bitumen Emulsions. A bitumen emulsion is a construction material with high adhesion properties with particles of 1 micron or less. The basic color of bitumen emulsion is brown, but it can be from  very light to dark depending on dispersion.

The emulsions most commonly used in construction are those with 50-55% bitumen. Among the most important properties of the material is sufficient viscosity, good storage stability and temperature from 0 to 50ºС.

After application onto the treated surface, the material separates into water and bitumen. The emulsion becomes black. Due to the high protection properties, applied emulsion waterproofs the underlying materials. Besides, the bitumen film is resistant to acids and alkali.

Bitumen dispersion is characterized by creation of a fine mass of separate small particles, increasing its total surface area. The smaller the particles, the larger the surface. Bitumen pulverization allows to create a dispersed system, but it only remains stable while stirred, separating as soon as stirring is stopped. To preserve the required dispersion and stability of the emulsion, the interfacial tension on the boundary between water and bitumen must be reduced. This is done with the help of special substances – surfactants. Bitumen particles absorb these on the surface, reducing interfacial tension and preventing coagulation.

The properties of bitumen emulsion are influenced by:

• bitumen grade;
• emulsifier properties.

Various organic and mineral substances can be used as surfactants. Most commonly used substances are fats, fatty acids, soaps, starch, lime, sulfuric cellulose, complex esters etc.

For industrial production of bitumen emulsion, GlobeCore UVB-1 units can be used. These units allow the production of either cationic or anionic emulsions. The quality of the product complies with all relevant world standards in road and civil construction.

Bitumen Applications. Bituminous materials or asphalts are extensively used for roadway construction, primarily  because of their excellent binding characteristics and water proofing properties and relatively low cost. Bituminous materials consists of bitumen which is a black or dark coloured solid or viscous cementitious substances consists chiefly high molecular weight hydrocarbons derived from distillation of petroleum or natural asphalt, has adhesive properties, and is soluble in carbon disulphide. Tars are residues from the destructive distillation of organic substances such as coal, wood, or petroleum and are temperature sensitive than bitumen. Bitumen will be dissolved in petroleum oils where unlike tar.

Nowadays, there are 4 forms of bitumen:

1.Cutback bitumen

2.Bitumen Emulsion

3.Bituminous primers

4. Modified Bitumen

Cutback bitumen

Normal practice is to heat bitumen to reduce its viscosity. In some situations preference is given to use liquid binders such as cutback bitumen. In cutback bitumen suitable solvent is used to lower the viscosity of the bitumen. From the environmental point of view also cut-back bitumen is preferred. The solvent from the bituminous material will evaporate and the bitumen will bind the aggregate. Cutback bitumen is used for cold weather bituminous road construction and maintenance. The distillates used for preparation of cutback bitumen are naphtha, kerosene, diesel oil, and furnace oil. There are different types of cutback bitumen like rapid curing (RC), medium curing (MC), and slow curing (SC). RC is recommended for surface dressing and patchwork. MC is recommended for premix with less quantity of fine aggregates. SC is used for premix with appreciable quantity of fine aggregates.

Bitumen Emulsion

Bitumen emulsion is a liquid product in which bitumen is suspended in a finely divided condition in an aqueous medium and stabilised by suitable material. Normally cationic type emulsions are used in India. The bitumen content in the emulsion is around 60% and the remaining is water. When the emulsion is applied on the road it breaks down resulting in release of water and the mix starts to set. The time of setting depends upon the grade of bitumen.   Bitumen emulsions are ideal binders for hill road construction. Where heating of bitumen or aggregates are difficult. Rapid setting emulsions are used for surface dressing work. Medium setting emulsions are p referred for premix jobs and patch repairs work. Slow setting emulsions are preferred in rainy season.

Bituminous primers

In bituminous primer the distillate is absorbed by the road surface on which it is spread. The absorption therefore depends on the porosity of the surface. Bitumen primers are useful on the stabilised surfaces and water bound macadam base courses. Bituminous primers are generally prepared on road sites by mixing penetration bitumen with petroleum distillate.

Modified Bitumen

Certain additives or blend of additives called as bitumen modifiers can improve properties of Bitumen and bituminous mixes. Bitumen treated with these modifiers is known as modified bitumen. Polymer modified bitumen (PMB)/ crumb rubber modified bitumen (CRMB) should be used only in wearing course depending upon the requirements of extreme climatic variations. The detailed specifications for modified bitumen have been issued by IRC: SP: 53-1999. It must be noted that the performance of PMB and CRMB is dependent on strict control on temperature during construction. The advantages of using modified bitumen are as follows Lower susceptibility to daily and seasonal temperature variations

• Higher resistance to deformation at high pavement temperature
• Better age resistance properties
• Higher fatigue life for mixes
• Better adhesion between aggregates and binder
• Prevention of cracking and reflective cracking

In turn, road construction bitumens can be liquid and viscous. Bitumen of the first type are used in surface treatment of road, saturation of gravel to make asphalt and bitumen mineral mix. Bitumen of the second type function is binder in construction of road top and other road construction operations, production of cold mix asphalt, surface treatment of gravel roads and gravel road tops.

In our days bitumen is widely used in construction, agriculture, industry and for protection from radiation. One of the main applications of this material is the construction of roads, structures, airports and residential buildings.

Bitumen Emulsion Production. Bitumen emulsion was first made in Europe in the beginning of the 20th century. With time, new equipment was developed to improve efficiency of production and the quality of the product.

At present, bitumen emulsion production is a complex physical and chemical process which requires special equipment.

Advantages of bitumen emulsions

There are currently two competing materials in road construction and repairs: bitumen and bitumen emulsion. Using hot bitumen cannot achieve the required quality of construction, due to a number of reasons:

• poor adhesion;
• uneven distribution of the binder across the surface;
• the need to remove moisture from the treated surface;
• no way to adjust material parameters according to the conditions of work;
• high power consumption to maintain the temperature;
• hazards due to the high bitumen temperature (160 ºС).

On the other hand, bitumen emulsions offer the following advantages:

• full adhesion to the surface;
• even filling of all pores and depressions;
• capability of application on a wet surface;
• adjustment of material parameters according to operation requirements;
• low power consumption;
• ability to use in temperatures from 30 to 70 ºС.

Bitumen emulsion production

Two phases are required for bitumen emulsion production: bitumen and water. Bitumen phase includes bitumen and special additives (softeners, plasticizers). Water phase contains water, emulsifiers, acid and stabilizers. Both phases enter the colloid mill, where bitumen is pulverized to micron sizes. Bitumen particles are suspended in water. In some cases, latex can be injected into the stream to make polymer-modified bitumen emulsion.

Depending on the required emulsion type, the proportions of water and bitumen phase may vary. It is mostly 50/50 or 70/30 (the first number indicates bitumen content).

Application of bitumen emulsion

Bitumen emulsion can be used for:

• tac coating;
• surface treatment of existing roads;
• replacement of current asphalt road top (recycling).

Bitumen emulsion production equipment

The following equipment is needed to make bitumen emulsion:

• a colloid mill, portioning devices for water and bitumen phase and controls;
• emulsion storage tanks;
• bitumen storage tanks;
• other material storage tanks;
• piping, pumps etc.

GlobeCore offers a unique bitumen emulsion plant, the UVB-1 type unit.

This equipment allows to:

• make high quality bitumen emulsion regardless of the quality of incoming bitumen by adding plasticizers, adhesion additives and thinners;
• produce all types of emulsions: CRS, CMS and CSS-1,2, as well as anionic emulsions of the corresponding types, including subtype h;
• dilute the blend concentrate with water directly in the unit;
• produce emulsions fully compliant with ASTM D 2397-98 and D977-98.

The UVB-1 are compact, simple in operation and servicing and are safe to operate (safety interlocks are in place).

Binder Production Binder Production. There are several options of bitumen-polymer binder production, but almost all methods include heating and mixing.

The most efficient methods known today employ dispersers (colloid mills) which evolved from regular agitators in bitumen tanks. In theory, bitumen-polymer binder can be made in any bitumen tank with a certain amount of polymer added. The mixture is stirred until the modifier fully dissolves. The total time needed for the production is determined by the temperature of bitumen and the efficiency of the agitator.

The essence of the process is that polymer particles swell when dissolved in malthene fraction, forming a shell over the unsolved part of the substance. The main function of the agitator is to remove the shell. The dry polymer particle can then continue to dissolve in bitumen.

For efficiency of the process, the bitumen-polymer mixture must be cycled through the disperser until the polymer is fully dissolved in bitumen.

There is an alternative technique, sometimes referred to as inline technology. It does not involve multiple passes of the material through a disperser, instead, the mix passes through the mill only once. It enters the disperser with the bitumen in solid state. The small size is achieved by passing the substance through the gap between the rotor and the stator of the mill. To complete the process of solving the polymer, the mixture is then stirred for two hours.

The process is essentially the transition of polymer from solid to liquid state by extrusion and mixing of the plasticized modifier with bitumen heated to a certain temperature.

As the components are moved, several processes occur:

• polymer extrusion;
• mixing of the anomalously viscous liquid with a certain amount of bitumen and production of polymer binding with high or superhigh polymer content;
• consequent mixing of the polymer bitumen concentrate with main bitumen stream in the proportions to achieve the required polymer concentration in the finished product.