Bitumen

Bitumen is a black or dark-colored solid, semi-solid or highly viscous liquid that can be found in different forms such us: rock asphalt, natural bitumen, tar and bitumen derived from oil, which is referred to as petroleum bitumen. Often coal tar that is drive from oil-shale, wood or other organic materials confused with bitumen. However they are two entirely chemically different products and should not be mistaken. Bitumen is a low grade of crude oil which is composed of complex heavy hydrocarbons and residue distillation tower refinery that is called Vacuum Bottom. Most refined bitumen is used in the construction industry. Mainly, it serves its use in paving and roofing applications, most of all bitumen is used as a binder in asphalt for roads, runways, Airport, Dams, Pipe coating, Paints, pools water proofing, cable coatings and many other applications. Gravel and crushed rock are mixed with thick bitumen, holding it together and it is then applied to roadways.

Bitumen packed normally as below :

  • In Bulk in vessel tank
  • In new steel drum with different sizes such as
    150 Kg, 180 Kg & 200 Kg each drum
  • In different sizes of poly bag or Bitu-bag such as
    Jumbo Bags, Poly Bags
  • In Flexi tank
  • In Carton


Air Blowing Bitumen

The Air Blowing Bitumen is produced by process of vacuum Bottom (VB) and air in the reactor or batch. And due to the control of the process conditions, different grades are produced. The regular distillation process is discontinued at some point while the topped crude is still liquid. The heavy fraction is into a converter and air is blown through it while it is maintained at a high temperature. This process is continued until the asphalt has attained desired properties. Often, such asphalts are called Blown asphalt. However, this is not strictly a true term because not only oxidation but also vaporization, Dehydrogenation, condensation, polymerization and other reactions occur during the air blowing process.

Types of Air Blowing Bitumen:


  • Penetration Grades
  • Performance Grades (PG)
  • Viscosity Grades (VG)
  • Different Penetration grade Bitumen

    • Penetration Grades Bitumen: are refinery bitumen that are manufactured at different viscosities. They produced by manufactured from fractional/vacuum distillation of crude oil (feed stock). The penetration test is carried out to characterize the bitumen, based on the hardness. Thus, it has the name penetration bitumen. It is usually used as a Paving Grade Bitumen essential for road construction and for the production of asphalt pavements with superior properties, and it's very important once it bounds the aggregates and creates a unique cohesion and stability to the bituminous mix. Penetration Grade Bitumen is specified by the penetration and softening point test. The designation is by penetration range only.

    Oxidized Bitumen

    Oxidized bitumen is categorized based on softening points and penetration rate. For example, oxidized bitumen 85/40 is a type of bitumen which softening point is 85±5 degree centigrade and its penetration are is 40±5 dmm. These types of bitumen is also expected to make up for weight loss under heat. And the softening point is much higher than in regular bitumen. Oxidized Bitumen is mainly used for industrial purposes such as roof insulation, pipe coating, paints, industrial mastics and etc.

    Performance Grades Bitumen (PG)

    Performance grades based on binder specification with a new set of tests (SHRP). And its performance at different temperatures, in Super pave grading system, binders are classified according to their performance in extreme hot and cold temperatures and called as performance grade (PG) bitumen. The PG system uses a common set of tests to measure physical properties of the binder that can be directly related to field performance of the pavement at its service temperatures by engineering principles. PG grades nomenclature with two factors: traffic and pavement temperature. Application of grades PG Bitumen are used in paving for both new construction and pavement rehabilitation and in both dense-graded and open graded Hot Mix Asphalt. And could also be used for sealing of edges of new to told paving and crack sealing. Other uses include spray applications for bridge deck and pavement protective membrane with fabrics.

    Viscosity Grades Bitumen (VG)

    Viscosity Grade Bitumen is a petroleum and have been specified in terms of their penetration grade and behavior changes according to its temperature. Viscosity Grade bitumen is specified by ASTM Standard and based on absolute Viscosity at 60 ̊C (140 °F) or Kinematic Viscosity at 135 ̊C. Viscosity thus defines the fluid property of the bituminous material. Viscosity is the general term for consistency and it is a measure of resistance to flow. Many researchers believe that grading of bitumen should be by an absolute viscosity in instead of the conventional penetration units. Application of VG grades: Viscosity Grade Bitumen is a standard grade Bitumen usually used as a Paving Grade Bitumen suitable for road construction and for the production of asphalt pavements with superior properties. This grade of Bitumen is mainly used in the manufacture of hot mix asphalt for bases and wearing courses and possesses characteristics and qualities unique sand quite different from other agents.

    Cut back Bitumen Grades Slow Curing (SC)

    Cutback Bitumen: Bitumen is ‘cutback’ by adding controlled amounts of petroleum distillates such as kerosene. This is done to reduce the viscosity of the bitumen temporarily so it can penetrate pavements more effectively or to allow spraying at temperatures that are too cold for successful sprayed sealing with neat bitumen. The materials used to cutback bitumen will evaporate after application to leave the remaining material similar in hardness to the original bitumen. Application of Cutback Bitumen: Cutback bitumen’s suitable for primer sealing can also be used in the manufacture of pre-mix asphalt, which is used in patch repairs. Cutback bitumen’s are used extensively in sprayed sealing applications, particularly in cooler weather where they provide improved initial stone retention due to their lower viscosity. Typically, a single application of the appropriate cutback bitumen is sprayed onto the primed pavement on to which aggregate is laid. Cutback Bitumen is categorized in 3 groups according to their curing time: • Slow Curing Cutbacks (SC) • Medium Curing Cutbacks (MC) • Rapid Curing Cutbacks (RC)

    Cut back Bitumen Grades Medium Curing (MC)

    Asphalt cutbacks use petroleum solvents for dissolving asphalt cement. The solvents are variously called distillate, diluents or cutter stock. If the solvent used in making the cutback asphalt is highly volatile, it will quickly escape by evaporation. Solvents of lower volatility evaporate more slowly. On the basis of the relative speed of evaporation, cutback asphalts are divided into three types: rapid curing (RC), medium curing (MC) and slow curing (SC). MC Cutback Bitumen is a compound of different oil solvents such as kerosene in order to transform bitumen to soluble bitumen which is evaporated in oil solvent using process and the bituminous layer is remained to make cohesion, penetration and form a sealing layer. A famous sort of it known as MC250 or liquid bitumen in asphalt section including pavement (cohesive between 2 Tack coat asphaltic layers), cold asphalt (Roadmix) and substructure (cohesive between asphaltic and soil layers-Prime coat) has been previously using in Iran. Available kerosene in MC250 would lead to promoting bitumen restoration, better penetration in infrastructure application (Primecoat) but yet will increase environmental hazards, price and heating cost in using and discharging time comparison with various types of water-based emulsions. Bitucut bitumen is produced and supplied in these types: MC800, MC250, MC70, MC30 and MC3000 which have the different percentage of solvent. Bitucut usage differs in various conditions such as substructure (continuous grading with low free space, open grading, and soil percentage). Using Bitucut in substructures (Primecoat) is the most demanded application in Iran. Medium curing (MC) asphalt cement uses medium diluents of intermediate volatility generally in the kerosene boiling point range ( MC-30, 70, 250, 800, 3000 ). The degree of liquidity developed in each case depends principally on the proportion of solvent to asphalt cement. To a minor degree, the liquidity of the cutback may be affected by the hardness of the base asphalt from which the cutback is made. The degree of fluidity results in several grades of cutback asphalt—some quite fluid at ordinary temperatures and others somewhat more viscous. The more viscous grades may require a small amount of heating to make them fluid enough for construction operations. The medium setting grades are designed for mixing with aggregates. Because these grades do not break immediately upon contact with aggregate, mixes using them can remain workable for extended periods of time and lend themselves to cold mix stockpiles.

    Cut back Bitumen Grades Rapid Curing (RC)

    Asphalt cutbacks use petroleum solvents for dissolving asphalt cement. The solvents are variously called distillate, diluents or cutter stock. If the solvent used in making the cutback asphalt is highly volatile, it will quickly escape by evaporation. Solvents of lower volatility evaporate more slowly. On the basis of the relative speed of evaporation, cutback asphalts are divided into three types: rapid curing (RC), medium curing (MC) and slow curing (SC). Rapid curing (RC) asphalt cement is a combination of light diluents of high volatility, generally in the gasoline or naphtha boiling point range (RC-70, 250, 800, 3000), and asphalt cement. The degree of liquidity developed in each case depends principally on the proportion of solvent to asphalt cement. To a minor degree, the liquidity of the cutback may be affected by the hardness of the base asphalt from which the cutback is made. The degree of fluidity results in several grades of cutback asphalt—some quite fluid at ordinary temperatures and others somewhat more viscous. The more viscous grades may require a small amount of heating to make them fluid enough for construction operations. The rapid-setting grades are designed to react quickly primarily for spray applications, such as bond/tack coats, aggregate chips seals, sand seals, and similar surface treatments.

    Bitumen Emulsions

    Bitumen Emulsion: Description 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. But as the bitumen is a petroleum product it doesn't mix with water and as it is sticky in nature, it doesn't easily gets disintegrated into fine droplets. To overcome this problem an emulsifier is used. Application of Bitumen Emulsions: Bitumen emulsion are applied on aggregates, water starts to evaporate causing separation of bitumen from water. And then bitumen spreads on the surface of the aggregate and acts as a binding material and slowly attains its strength. Also they are especially helpful for maintenance and patch repair works. And can be used in wet weather even when it is raining, have been used in soil stabilization, particularly for stabilization of sands in desert areas, for surface dressing and penetration macadam type of construction and overall allows better coating of the bitumen on the surface of aggregate. Types of Bitumen Emulsion: First Step the bitumen emulsion is divided to 3:
  • Anionic with negatively charged globules
  • Cationic with positively charged globules
  • Non-ionic with neutral globules
  • The term anionic is derived from the migration of particles of bitumen under an electric field. The droplets migrate toward the anode (positive electrode), and hence the emulsion is called anionic. In an anionic emulsion, there are “billions and billions” of bitumen droplets with emulsifying agent at the water bitumen interface. The term cationic is derived from the migration of particles of bitumen under an electric field also. The droplets migrate toward the cathode (negative electrode), and hence the emulsion is called cationic. The cationic emulsifying agent functions similarly to the anionic; the negative portion of the head floats around in the water leaving a positively charged head. The main grades for bitumen emulsions are classified as follows:
  • Rapid Setting Emulsion (RS)
  • Medium Setting Emulsion (MS)
  • Slow Setting Emulsion (SS)
  • The most Iranian apply of bitumen emulsion is Cationic grades.

    Other

    Polymer Modified Bitumen: Polymers represent the most important family of bitumen modifiers. The specifications of bitumen under different temperatures change, for example, polymers make bitumen resistant to heating cracks. Modifying the bitumen specifications boosts the quality of the product and increases its longevity. Under these special circumstances, structural destructions happen more quickly than in natural state in asphalt pavement and that would significantly increase road maintenance costs.

    Variety of Polymers: The most polymers that used for modifying bitumen are SBS, EVA, APP, LDPE, LLDE. HDPE, SBR, SEBS and SIS.

    SBS is one of the best modifying polymers with both thermoplastic and rubber specifications.

    Polymer Modified Bitumen are used in making pavement, roads for heavy duty traffic and home roofing solutions to withstand extreme weather conditions. PMB is a normal bitumen with the added polymer, which gives it extra strength, high cohesiveness and resistance to fatigue, stripping and deformations, making it a favorable material for infrastructure.

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