Bitumen is a product of Crude oil Distillation. It is a semi-solid hydrocarbon product produced by removing the lighter fractions (such as liquid petroleum gas, petrol and diesel) from heavy crude oil during the refining process. As such, it is correctly known as refined bitumen.
Known for its adhesive and cohesive assets, bitumen is mostly utilised in the construction industry. Bitumen is applied on road paving because it is viscous when hot, but solid once it cools down. Therefore Bitumen operates as the binder/glue for pieces of the aggregate.
The vast majority of refined bitumen is used in construction: primarily as a constituent of products used in paving and roofing applications. According to the requirements of the end use bitumen is produced to specification. This is achieved either by refining process or blending.
It is estimated that the current world use of bitumen is approximately 102 million tonnes per year. Approximately 85% of all the bitumen produced is used as the binder in asphalt for roads.
Bitumen is applied in construction and maintenance of:
In order realize the complexity of bitumen as a product an in-depth knowledge and detailed understanding for one of the way the roads are built is crucial. Specialists in bitumen know bitumen as an advanced and complex construction material, not as a mere by-product of the oil refining process. The ultimate paving material (also referred to hot mix asphalt concrete – HMAC or HMA) consists of about 93 – 97% mineral aggregate (stone), sand and filler. The remaining percentage is bitumen.
Bitumen emulsions are usually dispersions of minute droplets of bitumen in water and are examples of oil-in-water emulsions.
The bitumen content can be varied to suit different requirements and is typically between 30% and 70%. The primary objective of emulsifying bitumen is to obtain a product that can be used without the heating normally required when using cutbacks and paving grade bitumen. In the manufacture of bitumen emulsions, hot bitumen is sheared rapidly in water containing an emulsifying chemical (emulsifier). This produces very small particles of bitumen (the dispersed phase) dispersed in water (the continuous phase). The bitumen particles are stabilised in suspension and do not readily coalesce due to the presence of the emulsifier, which is concentrated on the surface of the bitumen particles. During application, the water in a bitumen emulsion is either lost by evaporation, or it may separate from the bitumen because of the chemical nature of the surface to which the emulsion is applied. This process is referred to as breaking. Because bitumen has a density only slightly higher than water, sedimentation of the bitumen droplets in an emulsion during storage is very slow. Emulsions can usually be regenerated after long storage times by gentle stirring to re-disperse the bitumen droplets.
Bitumen emulsions are available in many different forms, either cationic or anionic, with varying breaking or setting rates and binder types and contents.
The two most common basic emulsion types are designated by the letter 'C' for cationic emulsions, as in CRS (cationic rapid setting), and by the letter 'A' in anionic emulsions, as in ASS (anionic slow setting).
When the emulsion is being produced the cations are adsorbed by bitumen droplets, negatively ions remain in the water. The undeniably most complete field of use is represented by the rapid setting emulsions.
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.
The Co2Na group is the hydrophilic polar part. When in a solution in the continuous aqueous phase, the soap molecules become ionized; the Na (or K) ions are the cations adsorbed by the water and the rest of the molecules are the anions adsorbed by the bitumen globules.
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:
|Test on emulsions:|
|Viscosity, SayboltFurol at 25°C SFS||200||100||20||100|
|Viscosity, SayboltFurol at 50°C||20||100||100||400||50||450|
|Storage stability test, 24-h, %B||1||1||1||1||1|
|Demulsibility, 35 mL, 0.8% dioctyl sodium sulfosuccinate,%||40||...||40||...|
|Coating ability and water resistance:|
|Coating, dry aggregate
Coating, after spraying
Coating, wet aggregate
|Coating, after spraying||fair|
|Particle charge test||positive||positive||positive||positive||positive|
|Cement mixing test,%|
|Oil distillate, by volume of emulsion,%||3||3||12|
|Tests on residue from distillation test:|
|Penetration, 25°C, 100g, 5s||100||250||100||250||100||250||100||250||40||90|
|Ductility, 25°C, 5 cm/min, cm||40||40||40||40||40|
|Solubility in trichloroethylene, %||97.5||97.5||97.5||97.5||97.5|
Cutback Bitumen is made by reducing the viscosity of and ordinary bitumen by adding mostly petroleum type solvent. Cutback Bitumen are used because their viscosity is lower than that of neat asphalt and can thus be used in low temperature applications. After a cutback is applied the solvent evaporates away and only the Bitumen is left. A cutback bitumen is said to cure as the petroleum solvent evaporates. Cutback bitumen are typically used as prime coats and tack coats. Generally are divided into three groups depending on their volatility of the solvent added:
Slow Curing often called "road oils," are usually a residual material produced from the fractional distillation of certain crude petroleums. Traditionally any kind of aromatic, naphthenic and paraffinic oils are used. Slow Curing liquid bitumen materials can be prepared by blending bitumen with an oily petroleum fraction.
Medium Curing are a blend of Bitumen with lighter hydrocarbons such as kerosene.
Rapid Curing products are prepared with a light, rapidly evaporating diluent such as a naphtha or gasoline.
As a solvent required to produce a cutback asphalt, it is possible to use not only the above described petroleum type solvent but also a coal type solvent or may be a mixture of various solvents and an additive in order to further improve the performance of final products (e.g. anti stripping effect).
Each of these three types of liquid asphaltic materials is produced in six standard grades. The prefix of each grade denotes the type: SC for Slow Curing, MC for Medium Curing, and RC for Rapid Curing. The suffix, or grade number, denotes the consistency range of the material. In each type, grade 0 is the most liquid, grade 5 the most viscous, with the intermediate grades ranging in consistency in an orderly progression. At room temperature, the consistency of grade 0 materials resembles that of heavy cream while grade 5 materials have the consistency of heavy molasses in cold weather. These products "cure" by the evaporation of the petroleum diluent. Formerly the advantage of application of cutback asphalt mixtures is a difference in the reduced paving temperature. However in these days cutback asphalt are used mostly as prime coat and/or tack coat.
When cutback asphalts are used as a prime coat, the cutback asphalt is sprayed to the surface of untreated sub grade or base layers in order to fill the surface voids and protect the sub-base from water penetration; stabilize the fines and preserve the sub-base material and/or promote bonding to the subsequent pavement layers. When used as a tack coat, the cutback asphalt is applied between hot mix asphalt pavement lifts to promote adequate bonding. This cutback promoted adequate bonding between construction 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 (de-bonding) followed by longitudinal Wheel path cracking, fatigue cracking, potholes, and other distresses such as rutting that greatly reduce pavement life.
|Slow Curing (SC)||SC-70||SC-250||SC-800||SC-3000||Test Methods|
|Kinematic viscosity at 60°C, mm2/s||70||140||250||500||800||1600||3000||6000||ASTM D-2170|
|Flash point (Cleveland open cup), °C||66||-||79||-||93||-||107||-||ASTM D-92|
|Distillation test:||ASTM D-402|
|Total distillate to 360°C, volume %||10||30||4||20||2||12||-||5|
|Solubility in trichloroethylene, %||99||-||99||-||99||-||99||-||ASTM D-2042|
|Kinematic viscosity on distillation residue at 60°C, mm2/s||400||7000||800||10000||2000||16000||4000||35000||ASTM D-2170|
|Asphalt residue:||ASTM D-243|
|- Residue of 100 penetration, %||50||-||60||-||70||-||80||-||ASTM D-5|
|- Ductility of 100 penetration residue at 25°C, cm||100||-||100||-||100||-||100||-||ASTM D-113|
|Water, %||-||0.5||-||0.5||-||0.5||-||0.5||ASTM D-95|
|Medium Curing (MC)||MC-30||MC-70||MC-250||MC-800||MC-3000||Test Methods|
|Kinematic viscosity at 60°C, mm2/s||30||60||70||140||250||500||800||1600||3000||6000||ASTM D-2170|
|Flash point (Cleveland open cup), °C||38||-||38||-||66||-||66||-||66||-||ASTM D-92|
|Distillation test: Distillate, volume percent of total distillate to 360°C:||ASTM D-402|
|Residue from distillation to 360°C, percent volume by difference||50||-||55||-||67||-||75||-||80||-|
|Tests on residue from distillation:|
|Viscosity at 60°C, Pa||30||120||30||120||30||120||30||120||30||120|
|Ductility at 25°C, cm||100||-||100||-||100||-||100||-||100||-||ASTM D-113|
|Solubility in trichloroethylene, %||99||-||99||-||99||-||99||-||99||-||ASTM D-4|
|Water, %||-||0.2||-||0.2||-||0.2||-||0.2||-||0.2||ASTM D-95|
|Rapid Curing (RC)||RC-70||RC-250||RC-800||RC-3000||Test Methods|
|Kinematic viscosity at 60°C, mm2/s||70||14||25||500||800||1600||3000||6000||ASTM D-2170|
|Flash point (Cleveland open cup), °C||-||-||27||-||27||-||27||-||ASTM D-92|
|Distillation test: Distillate, volume percent of total distillate to 360°C:||ASTM D-402|
|Residue from distillation to 360°C, percent volume by difference||55||-||65||-||75||-||80||-|
|Tests on residue from distillation:|
|Viscosity at 60°C, Pa||60||240||60||240||60||240||60||240|
|Ductility at 25°C, cm||100||-||100||-||100||-||100||-||ASTM D-113|
|Solubility in trichloroethylene, %||99||-||99||-||99||-||99||-||ASTM D-4|
|Water, %||-||0.2||-||0.2||-||0.2||-||0.2||ASTM D-95|
Gilsonite is a natural, resinous hydrocarbon found in the Uintah Basin in northeastern Utah; thus, it is also called Uintahite. This natural asphalt is similar to a hard petroleum asphalt and is often called a natural asphalt, asphaltite, uintaite, or asphaltum. Gilsonite is soluble in aromatic and aliphatic solvents, as well as petroleum asphalt. Due to its unique compatibility, Gilsonite is frequently used to harden softer petroleum products. Gilsonite in mass is a shiny, black substance similar in appearance to the mineral obsidian. It is brittle and can be easily crushed into a dark brown powder. When added to asphalt cement or hot mix asphalt in production, Gilsonite helps produce paving mixes of dramatically increased stability.
|Ash Content||%Wt||2.0 - 10.0||ASTM D-3174|
|Moisture Content||%Wt||1.0 - 3.0||ASTM D-3173|
|Volatile Matter||%Wt||63||ASTM D-3175|
|Fixed Carbon||%Wt||29||ASTM D-3172|
|Solubility in CS2||%Wt||81.0||ASTM D-4|
|Specific Gravity at 25°C||1.01 - 1.06||ASTM D-3289|
|Normal HepthanInsolubles||%Wt||79||ASTM D-3279|
|Color in Mass||Black||-|
|Color in Streak or Powder||Brown||-|
|Softening Point||°C||180 - 205||ASTM D-36|
|Penetration at 25°C||0.1MM||0.0||ASTM D-5|
Blown bitumen grades or Oxidized Bitumen are produced by passing air through the penetration grades. This process gives the bitumen more rubbery properties than its original formula and they are simply harder bitumen. Hard bitumen under controlled temperature conditions is widely used as an anti-slip layer compound in the piling industry, for manufacture of roofing felts, the roofing and waterproofing industries, for sound dampening felts and under carriage sealant in the automotive industry, electric cable joint protection, joint filling compound, sealant compound and many others. Also used in sealing saw cuts and joints where expected movements are minimum. It is also used in the manufacturing of bituminous marine mastic for the oil & gas pipeline joints.
|BITUMEN R 85/25||BITUMEN R 85/40||BITUMEN R 95/25||BITUMEN R 95/40||BITUMEN R 115/15|
|Relative Density at 25 deg C, g/ml||1.00-1.06||1.00-1.05||1.00-1.05||1.00-1.05||1.00-1.06||ASTM D70|
|Softening Point (Ring and Ball), dec C||80-90||80-90||90-100||90-100||110-120||ASTM D36|
|Penetration at 25 °C, 0.1 mm||20-30||35-45||20-30||35-45||42663||ASTM D5|
|Flash Point ( Cleveland open Cup), °C, Min||200||200||200||200||200||ASTM D92|
|Loss on heating % by mass||0.2||0.5||0.2||0.5||0.2||ASTM D6|
|Ductility at 25 °C cm, min||2||2||2||2||2||ASTM D113|
|Solubility in toluene % wt min||99||99||99||99||99||EN12592:2000|
Penetration Grade Bitumen is Bitumen classified using the penetration property. Penetration grading’s basic assumption is that the less viscous the asphalt, the deeper the needle will penetrate. Bitumen which is produced during the process of oxidation of vacuum bottom (the Bitumen production feedstock that derives from distillation tower residue in vacuum oil refineries) at bitumen production unit in a manner that its penetration point (kind of test to indicate the hardness of bitumen) in specified group is classified in different grade of Bitumen. Penetration Grade Bitumen is commonly used in road surfacing, and some industrial applications. Additional processing yields other grades of bitumen products and their application
|Specific Gravity @25°C||-||1.01-1.06||1.01-1.06||1.01-1.05||1.01-1.04||ASTM D-70|
|Penetration @25°C, 100gm, 5sec||0.1MM||40-50||60-70||80-100||100-120||ASTM D-5|
|Softening Point, Ring & Ball||°C||52-60||49-56||45-52||42-49||ASTM D-36|
|Ductility @25°C, after TFOT, Min||CM||100||100||100||100||ASTM D-113|
|Loss on Heating, Max||%Wt||0.2||0.2||0.5||0.5||ASTM D-6|
|Drop in Penetration after Heating, Max||%||20||20||20||20||ASTM D-6 & D-5|
|Flash Point Cleveland open cup, Min||°C||250||250||232||250||ASTM D-92|
|Solubility in CS2, Min||%Wt||99.5||99.5||99.5||99.5||ASTM D-4|
|Organic Matter Insoluble in CS2, Max||%Wt||0.5||0.5||0.5||0.5||ASTM D-4|
Performance Grade (PG) bitumen is bitumen which is graded based on its performance at different temperatures. The Long-Term Pavement Performance(LTPP) has given certain algorithm to calculate the temperature of the pavement based on the temperature of the air above. From this, the highest and the lowest temperatures of the pavement is calculated and the bitumen that performs well in that temperature range is selected. Penetration grading and viscosity grading are somewhat limited in their ability to fully characterize asphalt binder for use in Hot Mix Asphalt(HMA) pavement. Therefore, as part of the Superpave research effort new binder tests and specifications were developed to more accurately and fully characterize asphalt binders for use in HMA pavements. These tests and specifications are specifically designed to address HMA pavement performance parameters such as rutting, fatigue cracking and thermal cracking.
|PG 46-34||PG 46-28||PG 52-28||PG 58-28||PG 58-22||PG 64-22||AASHTO Method|
|Flash Point, COC,°C||240||T-48|
|Flash Point, P-M, °C||NS||>204||ASTM D-93|
|Rotational Viscosity @ 135°C, Pa•s||3||T - 316|
|Dynamic Shear @ Grade Temperature,°C||46||46||52||58||58||64||T - 315|
|G*/sin @ 10 rad/sec, kPa||>1.00|
|Mass Loss, %||<1.00||T - 240|
|Dynamic Shear @ Grade Temperature,°C||46||46||52||58||58||64||T- 315|
|G*/sin @ 10 rad/sec, kPa||2.2|
|PAV Residue (Aging Temperature, °C)||90||100||R - 28|
|Dynamic Shear @ Grade Temperature,°C||10||13||16||19||22||25||T - 315|
|G*/sin @ 10 rad/sec, kPa||5000|
|S, Mpa||<300||T - 313|
|m-value||>0.30||T - 313|
Polymer modified emulsions have more durability and flexibility in comparison to standard emulsions and are usually recommended for better performance and durability, permitting to reduce life cycle costs when compared to regular emulsions. These modifications on normal emulsions by the use of modified bitumen have exhibited and demonstrate reductions in rutting, thermal cracking and increase significantly the resistance generally in traffic-subjected stress pavements.
|Designation||Elastomeric Thermoplastic Based||Plastomeric Thermoplastic Based||Natural Rubber Modified Binders||Crumb Rubber Modified Binders||Merthod of tests|
|PMB 120||PMB 70||PMB 40||PMB 120||PMB 70||PMB 40||NRMB 120||NRMB 70||NRMB 40||CRMB 50||CRMB 55||CRMB 60|
|Penetration at 25°C, 0.1mm,100g.5 Sec||90 to 150||50 to 90||30 to 50||90 to 150||50 to 90||30 to 50||90-150||50-90||30-50||<70||<60||<60||IS: 1203-1978|
|Saftening Point (R&B)°C Minimum||50||55||60||50||55||60||50||55||60||50||55||60||IS:1205-1978|
|Ductility at 27°C cm.||+75||+60||+50||+50||+40||+30||+75||+60||+50||-||-||-||IS:1208-1978|
|Fraass Breaking Point°C Max||-24||-18||-12||-20||-16||-12||-20||-16||-12||-||-||-||IS:9381-1979|
|Flash Point by COC°C Minimum||220||220||220||220||220||220||220||220||220||220||220||220||IS:1209-1978|
|Elastic Recovery of Half Thread in Ductilometer at 15°C, %, Min||75||75||75||50||50||50||50||40||30||50||50||50||Appendix-1 IRC:SP:53 2002|
|Separation Differnce in softening Point R&B°C, Maximum||3||3||3||3||3||3||4||4||4||4||4||4||Appendix-2 IRC:SP:53 2002|
|Viscosity at 150°C poise||1-3||2-6||3-9||1-3||2-6||3-9||-||-||-||-||-||-||IS:1206-1978|
|Thin Film Oven Test (TFOT) on Residue (IS:9382-1992)|
|Loss in Weight, %, Maximum||1.0||1.0||1.0||1.0||1.0||1.0||-||-||-||-||-||-||IS:9382-1979|
|Increase in Softening Point °C, Maximum||7||6||5||7||6||5||7||6||5||7||6||5||IS:12QS.1978|
|Reduction in Penetration of Residue at 25°C, Maximum||35||35||35||35||35||35||-||-||-||-||-||-||IS:1203-1978|
|Penetration at 25°C 0.1 mm, 100g, 5 Sec. Minimum % of original||-||-||-||-||-||-||60||60||60||60||60||60||IS:1203-1978|
|Elastic Recovery of Half thread in Ductilometer at 25°C, % Minimum||50||50||50||35||35||35||35||30||25||35||35||35||Appendix-1 IRC:SP:53 2002|
There are two methods of grading:
Standard Viscosity Grade Bitumen (AC-Grades), in which the Viscosity of the standard bitumen (asphalt) is measured at 60 ºC (140 ºF).
RTFOT Viscosity Grade Bitumen (AR-Grades), in which the Viscosity of bitumen (asphalt) is measured at 60 °C (140 °F) after the roll on thin film oven test.
Viscosity grade bitumens have a thermoplastic property which causes the material to soften at high temperatures and to harden at lower temperatures. This unique temperature/ viscosity relationship is important when determining the performance parameters such as the adhesion, rheology, durability and application temperatures of bitumen. In the Viscosity Graded Bitumen specifications further special emphasizes is placed on the Bitumen ductility.
|Viscosity Grade Bitumen Specification|
|Penetration at 25°C, 100g, 5sec, Min||0.1MM||80||60||45||35||IS 1203|
|Absolute viscosity at 60°C||P||800-1200||1600-2400||2400-3600||3200-4800||IS 1206 (Part 2)|
|Kinematic viscosity at 135°C, Min||cSt||250||300||350||400||IS 1206 (Part 3)|
|Flash point (Cleveland open cup), Min||°C||220||220||220||220||IS 1448 [P : 69]|
|Solubility in trichloroethylene, Min||%Wt||99||99||99||99||IS 1216|
|Softening point (R&B), Min||°C||40||45||47||50||IS 1205|
|Tests on residue from thin film oven test:|
|- Viscosity ratio at 60°C, Max||4||4||4||4||IS 1206 (Part 2)|
|- Ductility at 25°C, Min||CM||75||50||40||25||IS 1208|