Additive- Any substance that is added in small proportions to Bitumen to impart some particular property e.g. improved adhesion, emulsification etc.
Adhesion agent- An additive that forms a water-resistant chemical bridge between binder and aggregate surface, and hence improves adhesion.
Anti-foam agent - A substance, e.g. silicone oil, which when added to a Bitumen will reduce the surface tension and hence the frothing tendency of hot Bitumen in the presence of water.
Asphalt A mixture of mineral aggregate and a bituminous binder. A natural mixture in which Bitumen is associated with a substantial proportion of inert mineral matter.Note: In the US Asphalt is used as the term for the Bitumen itself.
Asphaltenes: The high molecular weight hydrocarbon fraction precipitated from Bitumen by a designated paraffinic solvent.
Auto-ignition temperature - The temperature above which a substance, when exposed to air, might ignite in the absence of a source of ignition as a result of contact with a hot surface or by self-heating alone. Auto-ignition temperature is not an intrinsic property of the substance. It depends upon the surrounding physical circumstances including the size and shape of the substance and the degree of ventilation around it. Therefore, the auto-ignition temperature for any substance can only be indicated approximately.
Bituminous Binder: A modified Bitumen or mixture of Bitumen with fluxes, etc used for road sealing or the manufacture of asphalt mixes.
Bitumen- A virtually in-volatile, adhesive and waterproofing material obtained by refinery processes from crude petroleum, or present in natural asphalt deposits in some parts of the world. It is black or brown in colour and completely or nearly completely soluble in toluene. It is very viscous or near solid at ambient temperatures and softens gradually when heated.
Bitumen emulsion- A dispersion of Bitumen in water achieved by the use of suitable chemical emulsifying agents. The emulsified Bitumen droplets may be anionic (negative charge), cationic (positive charge) or non-ionic (neutral).
Blown Bitumen (Oxidised Bitumen) - Bitumen used in a wide variety of 'industrial' applications including roofing, flooring, pipe-coating etc. They are produced by passing air through soft Bitumen /flux mixtures under controlled temperature conditions. British Standard grades (BS 3690) are normally designated by two numbers representing the mid-points of their softening point and penetration ranges.
Boil-over (Froth-over): The rapid increase in volume caused by the presence of water in hot Bitumen and the subsequent overflow from a tank.
Cutback Bitumen- Bitumen whose viscosity has been reduced by the addition of a relatively volatile flux such as kerosene, to render it more fluid for ease of application.
Emulsifier: A chemical additive that is used to stabilise a suspension of Bitumen in water in emulsion manufacture. The emulsifier determines the charge of the emulsion and controls the stability.
Flash point - The lowest temperature at which the application of a small flame in a prescribed manner causes the vapour above a flammable product to ignite when the product is heated under prescribed conditions. The flash point may be measured according to IP Method 34/88 or equivalent in a Closed Cup or by IP 36/84 in an Open Cup.
Flux: A fluid added to Bitumen to reduce its viscosity. Note also blowing flux - heavy petroleum liquid that is added to Bitumen to facilitate the production of oxidised grades.
Fume: Vapour carrying suspended solid particles or liquid droplets.
Gantry: A fixed structure providing access to the top of a transport vehicle for loading or discharging operations. Hard grade Bitumen: These are manufactured in a similar way to paving grade Bitumen. They have lower penetration values and higher softening points than paving grade Bitumen. Hard paving grade Bitumen is used in the manufacture of high modulus asphalts.
Occupational exposure standards (OES):
The contaminant concentrations in the working atmosphere annually set, in the UK by the Health and Safety Executive, either as limits which should not normally be exceeded or as limits of good practice. These limits are normally set as Long Term Exposure Standards (8-hour time weighted average values) and/or as Short Term Exposure Limits (10-minute time weighted aver-age maximum exposure limits (MEL). Oxidised grade Bitumen:See blown Bitumen. Pascal-Seconds (PaS): The SI unit for viscosity. 1 Pascal-second equals 10 poises. Paving grade Bitumen: Bitumen used to coat mineral aggregate in the construction and maintenance of paved surfaces. They are usually produced by vacuum distillation of petroleum, followed in some cases by oxidation/blending process. British Standard Grades (BS EN 12591) are normally designated by the range of the penetration values.
Penetration value - A measure of the consistency of Bitumen, determined as the depth to which a standard needle penetrates the sample under the conditions prescribed by BS EN 1426 or equivalent.
Penetration Index (PI) - A measure of the way the binder's consistency (penetration value) changes with temperature. It may be calculated from the penetration at two different temperatures or from the penetration at one temperature and the softening point.
Polycyclic Aromatic Hydrocarbons (PAH)- Also synonymously known as 'Polycyclic Aromatics (PCA)' or 'Poly-nuclear Aromatics (PNA)'. High boiling members of the family of ring type aromatic hydrocarbons present in the low percentage range in Bitumen, some of which, with four to six fused rings and present in minute traces in Bitumen. Polymer Modified Bitumen
(PMB)- Bituminous binders containing selected polymers to produce enhanced performance characteristics. They can be used in the same variety of applications as unmodified Bitumen.
Pyrophoric deposit: A deposit normally formed in an oxygen depleted environment, which can produce self-heating when its temperature or the surrounding oxygen concentration is increased.
Rheology - Physical study of the deformation of materials linked to viscosity, elasticity, plasticity and flow.
Slurry Seal: A mixture of Bitumen emulsion, well-graded fine aggregate, mineral filler or other additives, and water. Slurry seals are used as surface treatments in road maintenance.
Softening point: The temperature in degrees C at which a Bitumen attains a particular degree of softness with reference to test conditions prescribed by BS EN 1427 or equivalent. Soft Paving grade Bitumen: Paving Bitumen used in the manufacture of soft asphalt.
Viscosity: A measure of the resistance of a fluid to flow. Various scales of measurement are used. The Standard Tar Viscometer (STV) is used in the IP Method 72/86 to characterise cutback Bitumen in 'seconds'. Kinematic viscosity is a derived characteristic that can be used to represent the fluid in technical calculations.
CONVERSIONS OF PETROLEUM PRODUCTS
Products TOE/Tonne Barrels/Tonne Refinery Gas 1.150 8.00 Ethane 1.130 16.85 LPG 1.130 11.60 Aviation Gasoline 1.070 8.90 Motor Gasoline 1.070 8.53 Jet Gasoline 1.070 7.93 Jet Kerosene 1.065 7.93 Other Kerosene 1.045 7.74 Naphtha 1.075 8.50 Gas / Diesel Oil 1.035 7.46 Heavy Fuel Oil 0.960 6.66 Petroleum coke 0.740 5.50 White Spirit 0.960 7.00 Lubricants 0.960 7.09 Bitumen 0.960 6.08 Paraffin Waxes 0.960 7.00 Non specified Products 0.960 7.00
TOE : Tonne of Oil Equivalent
Comparitive Study of Bitumen Standards Bitumen is a visco-elastic material, whose properties are affected by both the temperature and the time during which a force is applied to it (loading time). Different grades of Bitumen reflect differing (visco-elastic) resistance to deformation.
To measure this resistance, many generic characterisation tests have been devised including measures of brittleness, temperature susceptibility (penetration index), softening point, penetration value and viscosity. Additionally, more fundamental tests have been developed such as kinematic viscosity, dynamic shear, bending beam and direct tension testing. These are all used to characterise the relative performance of the Bitumen at different temperatures.
The two traditional tests used to characterise Bitumen, and to designate the different grades, are the penetration value (usually at 25ºC) and the softening point (Ring & Ball).
Other tests used in UK Bitumen specifications to cover the main quality parameters are: • Resistance to Hardening - tendency for Bitumen to harden under the action of heat and air • Flash Point - information required for safety in handling • Solubility- - indicates the purity (lack of contamination) of the product
Many other properties are of course measured in Bitumen development work and to assess performance characteristics in the various applications.
Most of the Bitumen producing nations including Saudi Arabia, Thailand, Singapore, Iran, Malaysia and New zeland in Asia uses the penetration test (ASTM D-5) ( also cited in TNZ/M/1 in New eland’s standards) as against their Australian counterparts who uses the viscosity to define the grade of Bitumen. This has given rise to difference in manufacturing standards between the rest of its neighbours.
Grading as per D-5, carried out under laboratory conditions at 25 deg C to determine the depth that a weighted needle skins into Bitumen specimen over 5 seconds. Thus the higher the grade, the softer the Bitumen. It is measured in tenths of a millimetre. 60/70 grade has a depth of penetration between 6 & 7 millimetres.
This test, although look crude, is still internationally used as it serves as a reference point to compare the property of the Bitumen at higher temperatures and it’s consistency with regards to Softening point and viscosity with reference to its physical characteristics, simply at the ambient temperature, are graded as
180/200 Softer Sealing 130/150 Soft Sealing 80/100 Hard Hot mix Asphalt binder, sealing 60/70 Harder Hot mix Asphalt binder
Most of the nations like New zeland has two or less refineries, which cannot cater to their local demand, the additional requirements for the road construction are being imported.
Australian Standard
Australia uses the viscosity of the Bitumen to define the grades of Bitumen. This is in total contrast with the simple and internationally followed standard of Penetration test per ASTM D-5.
To comply with AS 2008, the viscosity of the Bitumen is tested at 60 deg C to define the four grade of Bitumen used for pavement construction.
Many other properties are of course measured in Bitumen development work and to assess performance characteristics in the various applications.
Grade Viscosity International Character Application Class 50 40-60 No Equivalent Softer Sealing Class 170 140-200 80/100 Soft Sealing Class 320 260-380 60/70 Hard Hot mix Asphalt , sealing Class 600 500-700 40/50 Harder Hot mix Asphalt
Viscosity is a measure of consistency and higher the viscosity,the harder the Bitumen gets.
The advantages of using Viscosity over the Penetration tests are
• Viscosity is independent of the test system and the sample size. • At 60 deg C, the testing range is close the pavement temperature • Comparative studies of viscosity over a range from 60-150 deg C yields the Bitumen temperature susceptibility.
Bitumen Pricing
The fluctuating Oil prices although justifies the fluctuation in the pricing of Bitumen. There is not an established mechanism to derive the Bitumen price till date. The Bitumen market is getting mature and liquid. The majority of the exporting nations include Singapore, Iran, Saudi Arabia, Egypt, Thailand in this region has different inputs and the range varies significantly.
For Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) there are no posted prices except for some compiled prices from some paid subscription services; marketers rely on a number of pricing formulas that reference various posted crude qualities.
Market pricing is seasonal with higher prices during peak season like summer being the norm due to higher demand for Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen).
By necessity, Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) is regularly blended with diluents (typically in the form of C5+ or synthetic light crude) in order to facilitate its transportation via pipeline to tankers.
As such, the effective field price for Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) is also directly impacted by the input cost of the diluents required, the demand and price of which is also seasonal in nature (in winter as colder temperatures necessitate more diluents for transportation).
Consequently, Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) pricing is high in summer and during major shutdown by the refineries and not reflective of the annual average realized price or the economics of the business overall.
The strong Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) demand disturbs the effective field prices during peak season for a variety of reasons. In addition to the usual seasonal issues, increase in Bitumen demand and the premium for diluents was significant as a consequence of various events such as production interruptions at a regional refinery.
The absence of a generally recognized approach to the determination of appropriate Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) pricing, coupled with the pricing seasonality (which has not been sufficiently addressed) meant that any number of interpretations existed as to how year-end Bitumen Grade prices should be determined, for the purpose of filing to the regulatory authorities, as well.
With billions of barrels of potential and billions of dollars of planned capital investment, the Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) resources are widely understood to be a cornerstone of future energy requirements. It is in the best interest to all stakeholders that a year-round Bitumen pricing methodology be established that reasonably reflects the general market conditions and is not unduly influenced by seasonal demand, shut-down at the refineries, Heavy and light crude differential, weather-driven or cataclysmic price movements.
SURFACE MINING- EXTRACTION
HISTORY G.C. Hoffman of the Geological Survey of Canada first attempted the separation of Bitumen from oil sand with the use of water in 1883. In 1915, Sidney Ells of the Federal Mines Branch began to study oil sands separation techniques and used the Bitumen to pave 600 feet of road in Edmonton, AB that lasted for 50 years.
Dr. Karl Clark of the Alberta Research Council, after extensive experimentation, was granted a patent for the hot water extraction process in 1928. The present extraction process is still very much based on the methods used decades ago.
CONDITIONING The first step in separating Bitumen from sand is conditioning. In this step, any large lumps of oil sand are broken up and coarse material is removed. The oil sand is then mixed with water. One of the earlier methods to condition oil sand was to mix it with hot water in huge tumblers or conditioning drums. This mixture of water and oil sand is called slurry.
The tumblers introduced air into the slurry and screened it to remove coarse material. A newer approach eliminates tumblers or conditioning drums altogether. After the oil sand is crushed at the mine site, it is mixed with warm water and then moved by pipeline to the extraction plant. The piping system is called hydro transport, this is one of the most exciting new developments in oil sands processing.
Hydro transport is cost effective and efficient. It replaces the old conveyor system between the mine and the extraction plant. It basically combines two steps into one. It conditions the oil sand while moving it to extraction. The water used for hydro transport is cooler than in the tumblers or conditioning drums, further reducing energy costs.
Conditioning by either method is an important step that launches complex physical and chemical changes. It starts the separation of the Bitumen ( grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) from the sand by breaking the bonds that hold the Bitumen ( Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) water and sand together.
SEPARATION
The blended slurry is fed into a Primary Separation Vessel (PSV) where it is allowed to settle into three layers. Additional hot water is added as the slurry arrives which allows separation to take place rapidly. Impure Bitumen froth floats on top, sand sinks to the bottom and a combination of Bitumen (grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) , sand, clay and water sits in the middle (known as middlings).
The settling and separation takes approximately 20 minutes. The PSV has a rake at the bottom that pulls the sand down and speeds up the separation. The sand, mixed with water, is pumped into settling basins called tailings ponds.
SECONDARY SEPARATION
The middlings is a suspended mixture of clay, sand, water and some Bitumen (grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen). The middling’s go through a process called secondary separation. There are different methods, but basically it involves injecting air into the middlings in flotation tanks. This added air encourages the creation of additional Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) froth.
The intent is to recover a further 2 – 4% of Bitumen . Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) from the secondary recovery system is recycled back to the primary system. Steam is used to heat the froth (to approximately 80°C) and remove excess air bubbles, in a vessel called a de-aerator. Air must be removed, to allow pumps to operate efficiently FROTH TREATMENT Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) froth is far from pure, it contains, on average, about 30% water and 10 % solids (mainly clays) by weight. De-aerated Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) froth from the extraction area is now cleaned of solids and water in the froth treatment plant or counter-current decantation vessels (Albian Sands). At the froth treatment plant the Bitumen ( includes grades of Bitumen 80/100, Bitumen 60/70, Bitumen 40/50, Oxidized Bitumen, Cutbacks including Meduium Curing Bitumen and Rapid Curing Bitumen) is diluted with naphtha, to make it flow easily and then goes through a combination of Inclined Plate Settlers (IPS), and Centrifuges. Inclined plate settlers allow for particles to settle efficiently under gravity, in a relatively small vessel by increasing settling area with inclined plates.
A centrifuge uses centrifugal force to spin heavier materials outward. There are two types of centrifuge in operation in froth treatment: • The scroll centrifuge is used to spin out coarser particles, and relies on an auger like action to convey solids out of the machine • The disc centrifuge is used to remove the finer material, including very small water droplets. The disc centrifuge works like a spin cycle on a washing machine and spins the remaining solids and water outward. This stream is collected as tailings Centrifuges may eventually be phased out, as IPS separation is advancing considerably. The clean diluted Bitumen product is now dry (less than 5% water) and with only small amount of solids (0.5% mineral).
This completes the extraction process. This hot water extraction process recovers over 91% of the Bitumen contained in the oil sand feed. The Bitumen is now ready to be upgraded into synthetic crude oil.
Froth treatment tailings have trace amounts of naphtha, which is recovered in a stream-stripping column called a NRU (naphtha recovery unit), before the tailings are discharged to the tailings ponds. The counter-current decantation vessels at Albian Sands mix solvent with the Bitumen feed. Water, solids and some ashpaltenes (heaviest component of Bitumen) are removed. The end result is clean diluted Bitumen called Dilbit. The Dilbit is sent down the Corridor pipeline to the Scotford Upgrader where the Bitumen is processed further.
Blending Plastic with Bitumen
Double the durability. The offer that comes with plastic-blended roads is welcome in a city increasingly identified by its battered roads. But the cost of technical upgrades and low customer patronage are also leaving holders of this patented technology struggling to keep afloat.
K K Plastic Waste Management (KKPWM), that pioneered the model of plastic-blended bitumen on Bangalore's roads, now plans to upgrade the technology to reach out to more. After discussions with venture capitalists failed to make headway, the proprietors are finalizing plans to start out on their own.
Under partnership with the Bruhat Bangalore Mahanagara Palike (BBMP), about 600 km of Bangalore's roads have been laid with the plastic-bitumen blend that, experts say, ensures almost double the durability of normal roads. Ahmed Khan, MD of KKPWM, says the plan is to upgrade from the present dry mix model to a wet mix model. KKPWM has bought five acres of land near Kunigal to construct a wet mix unit at an estimated cost of about Rs 5 crore. "In the dry mix model, our staff have to monitor the entire process of mixing bitumen with plastic on the construction sites. With the wet mix, we'll be able to mix this blend with tar and supply it as a complete product. It has immense potential as an industry,'' says Khan. Rasool Khan, director of the company, says the extra cost (see box) involved is balanced out by the extra durability. The plastic model has been used on M G Road, Cunningham Road, K H Road, J C Nagar Road, Shankar Mutt Road, Miller's Road, Cubbon Road and old roads like one in Dollars Colony.
CALL FOR MORE TAKERS
The technology involves blending of bitumen and plastic, both non-biodegradable. According to sources, more MoUs between the BBMP and KKPWM are in the pipeline but the company is also looking at partnering Bangalore Development Authority (BDA) and the public works department.
"The BBMP is our only end-user. There's a need for more civic agencies to join in,'' says Khan. Under the dry mix model, waste is segregated and powdered at the KKPWM unit and blended in equal measure with bitumen at the construction site.
THE BIG IDEA
Ahmed Khan, an entrepreneur from Krishnarajapet in Mandya, used to deal in plastic products. After the call against plastic became shriller during the mid-1990s, Khan thought of a creative way to deal with the issue and hit upon the idea of plastic-blended bitumen on roads. In partnership with researchers in road engineering, the technology was custom-made and experiments were done on roads in Maddur in 2001. The technology has found favour but is banking on bigger investment and better patronage to make the next level.
WASTE PRODUCT Bangalore generates 35 tonnes of plastic per day KKPWM collects 4 tonnes, pays rag-pickers Rs 6-12 per kg BBMP purchases waste from KKPWM at Rs 27 per kg Plastic road costs Rs 40,000 extra per km 2 tonne plastic needed for every km of road (3.5 m wide)
BEST MIX Tar Mix of metal aggregate, asphalt as binder Cost: Rs 1.5-Rs 2 cr Concrete Mix of metal aggregate, cement as binder Cost: Rs 4.5 cr* Plastic Plastic waste is cleaned, segregated and powdered. Mixed with bitumen, blended with other aggregates, then laid Cost: Rs 1.5-Rs 2 cr Making an accurate comparison between a tar and concrete road could be a tough ask because the performance of roads depends on many factors, including the volume of traffic. -- Krishnareddy, chief engineer (major roads), BBMP * Cost comparative for 3.5-m wide road of 1 km, with medium volume of traffic * While initial investment is higher on concrete road, recurring maintenance cost is low
Recyling of Bitumen
Recycling is becoming part of the production process in many industries and the asphalt sector is no exception. The advantages of reprocessing reclaimed asphalt are not just economic in an increasingly price sensitive market, the process also preserves a valuable natural resource. Prior to the asphalt planings being used in the recycling process, they have to be broken down to an acceptable size without reducing the original stone content. Benninghoven has developed recycling granulator to break asphalt blocks and plannings to a recyclable size without reducing the original stone content thereby creating minimum fines, all at the most economic production level. The planings are fed into a single shaft granulator where they are broken down and fed up to a single deck screen.
Materials go into the feed hopper and are forced in the single shaft granulator by oscillating hydraulic rams. The granulated material is then conveyed to the single deck screens after passing a magnetic belt detector, which removes any metal in the feed. The single deck screen separates the ready to size material for stockpiling, the oversize material is passed through the secondary double shafted granulator. This double shaft granulator is equipped with an adjustable setting to enable final product grading. The final material is produced to meet acceptable gradings that enables further processing to give maximum economical results.
Cold recycling
Reclaimed asphalt planings can be added in quantities of up to 25% direct into the asphalt plant paddle mixer, where it is mixed homogenously with virgin aggregates. This method is in common use throughout the UK and Ireland for processing small percentages of RAP.
A further innovative add on system, which can result in up to 35% asphalt planings being processed, is by using the existing plant dryer. Here the planings are introduced into the discharge end of the dryer via a slinger conveyor to mix with new material in the drum. Heat transfer continues during the materials movement to the plant mixing section, where it bypasses the screen and is introduced to the mixer through the weigh section.
Hot recycling
Although hot asphalt recycling has become an accepted practice throughout Europe, it is only now that operators are striving to keep down costs, maximising their operating efficiency together with projecting a more sustainable image, that they have started to embrace this new technology. Where larger quantities of reclaimed asphalt planings need to be processed - above 35% and up to 100% - then hot recycling is the only option. For many years Benninghoven have been developing new and improved methods of processing these waste asphalt materials. Their designs have made possible this high percentage of RAP recovery and provided operators with equipment, which helps preserving valuable natural resources.
A feature of the hot recycling plant is that the drum is mounted at high level to facilitate the movement of reclaimed materials into the existing asphalt plant process. At the heart of the system is a separate 11 m long large volume uniflow drum, which both dries and heats the recycled asphalt. The design of the drum internals ensures the burner flame makes no contact with the moving reclaimed material inside the drum. In the heat exchange zone, material travels smoothly through the cross section of the drum, which results in optimum heating combined with economic use of the burner and low exhaust gas temperatures.
In the next hot gas zone the materials are agitated, so protecting the drum skin from thermal overheating. The combustion zone of the hot RAP drum is fitted with special finger lifters, which vibrate during the production process to prevent clogging of the material during the heating process. The drum is fully lagged to minimise radiation loss and insulated with special zinc coated steel. Drive is by four 22 kW geared motors with friction drive.
A special compact, multi-fuel burner, which can burn a variety of fuels, including oil, natural gas, liquefied gas and coal, is used and is fitted with its own internal axial fan which provides the total air required for the combustion process. Frequency inverter control of the main blower fan provides the benefits of a perfect air/fuel ratio throughout the burner's operating range, thereby obtaining optimum running efficiency.
Hot recycled materials are discharged from the drum through an enclosed conveyor then by chute into a holding buffer silo. This is fully insulated and clad to maintain the temperature of the materials. From here it is batch weighed to the plant mixer as required. A feature of hot recycling systems is that the drum is mounted at a high level to facilitate the movement of the reclaimed materials into an existing plant process.
In recent months, Benninghoven have secured a major order for a state-of-the-art, high level, hot recycling plant for a site at West Drayton, with installation to start in May 2008. This will be the first plant of its type in the UK. Courtesy- http://www.bitumenexchange.com , http://bitumenexporter.blogspot.com
Bitumen Standards
This article attempts to have a re-look at a comparitive study of bitumen standards acorss Asia and the key differences in evaluation to suit the local needs.
Most of the bitumen producing nations including Saudi Arabia, Thailand, Singapore, Iran, Malaysia and Newzeland in Asia uses the penetration test (ASTM D-5) ( as specified by TNZ/M/1 in Newzeland's standards) as against their Australian counterparts who uses the viscosity of the bitumen to define the grades of bitumen. This has given rise to difference in manufacturing standards between the rest of it's neighbors.
Grades as per D-5, carried out under laboratory conditions at 25 deg C to determine the depth that a weighted needle skins into bitumen specimen over 5 seconds. Thus the higher the grade, the softer the bitumen. It is measured in tenths of a millimeter. 60/70 grade has a depth of penetration between 6 & 7 millimeters.
This test, although look crude, is still internationally used as it serves as a reference point to compare the property of the bitumen at higher temperatures and it’s consistency with regards to Softening point and viscosity.
with reference to it’s physical characteristics, simply at the ambient temperature, are graded as
180/200 Softer Sealing 130/150 Soft Sealing 80/100 Hard Hot mix Asphalt binder, sealing 60/70 Harder Hot mix Asphalt binder
Most of the nations like Newzeland has one or more than one refinery , which cannot cater to their local demand, the additional requirements for the road construction are being imported.
Australian Bitumen
Australia uses the viscosity of the bitumen to define the grades of bitumen. This is in total contrast with the simple and internationally followed standard of Penetration test per ASTM D-5 .
To comply with AS 2008, the viscosity of the bitumen is tested at 60 deg C to define the four grade of bitumen used for pavement construction.
Grade Viscosity International Character Application Class 50 40-60 No Equivalent Softer Sealing Class 170 140-200 80/100 Soft Sealing Class 320 260-380 60/70 Hard Hot mix Asphalt , sealing Class 600 500-700 40/50 Harder Hot mix Asphalt
Viscosity is basically a measure of consistency and higher the viscosity , the harder the bitumen gets. Recently India has introudcued Viscosity based Bitumen grades like VB10, VB30 etc..
The advantages of using Viscosity over the Penetration tests are
• Viscosity is independent of the test system and the sample size. • At 60 deg C, the testing range is close the pavement temperature • Comparative studies of viscosity over a range from 60-150 deg C yields the bitumen’s temperature susceptibility.
Bitumen emulsion is a combination of three basic ingredients, Bitumen, water, and small amount of an emulsifying agent. These ingredients are introduced into a process which shears the bitumen into tiny droplets. The emulsifier, which is a surface-active agent, keeps the Bitumen droplets in a stable suspension and controls the breaking time. The final product is a liquid product with a consistency ranging from that of milk to heavy cream and can be used in cold processes for road construction and maintenance. Advantages of Bitumen emulsions Bitumen emulsion does not require a petroleum solvent to make it liquid and in most cases Bitumen emulsions can be used without additional heat. Both of these factors contribute to energy savings. Additionally, Bitumen emulsions offer great flexibility in their application since they offer the end-user a great variety of characteristics not found in other paving and maintenance materials. Bitumen emulsions are environmentally friendly. There are little or no hydrocarbon emissions created with their use. History of Bitumen emulsions Bitumen emulsions were first prepared in the early part of the 20th century and today they are used all over the world. The use of Bitumen emulsions is growing and 10-20% of all Bitumen is used in the form of Bitumen emulsions. Classification of Bitumen emulsions
Bitumen emulsions are classified into three categories; Anionic Cationic and Nonionic The anionic and cationic classes refer to the electrical charges surrounding the Bitumen particles. The absence of the letter "C" denotes anionic emulsions.
Bitumen emulsions are further classified on the basis of how quickly they coalesce; i.e., revert to Bitumen cement.
RS (Rapid Set), MS (Medium Set), SS (slow set), and QS (Quick Set) have been adopted to simplify and standardize this classification.
Additionally, trailing numbers are used to delineate the relative viscosity if the emulsion and the letters "h" and "s" indicate whether a hard or soft base Bitumen is used to make the Bitumen emulsions.
The HSE issue can be classified into three working level. Producer Each Producer has a responsibility for providing sufficient data and applicable labelling and warnings so that his product can be safely handled and applied. Of course, that also implies that he has to control his raw materials and production so that his information is correct for each batch he is supplying.
User Worker Protection: Each employer has the responsibility for the safety of his workers that they can work safely with the material they use, the tools, the tasks, i.e. that they can do the jobs safely over time. The employer will need data for the products provided to him by the producers for that.
Government Authorities develop and deploy regulations to ensure that a minimum protection of the workers and the environment is established, and is applied by all. The absence of regulations does not exempt the employers and producers from their responsibilities. In the case of bitumen, there is no cancer classification so far.
In other words, it is the responsibility of each producer to classify the products he put on the market. Industry’s responsibility in developing information in HSE related matters will increase in the future.
• To provide relevant information to promote the safe use of bitumen
• To provide data to answer key health and regulatory questions
• To provide data that is accepted by the broad scientific community
Increasing pressure by the vehicular traffic on the road is compelling highway authorities to look for high performance bitumen, obtained by modifying it with natural rubber. Because of the positive elements in it and being cost effective, rubber-modified bitumen is an ideal proposition in the construction of highways, say experts.
Attempts had been made to modify the bitumen with plastomers and elastomers. ``Of these it was found that the natural elastomer, natural Rubber , was the most suitable modifier because of a number of reasons.
The advantages of NR in bitumen are that it is cost effective; does not induce stiffness to force road to brittle; improve resistance to flow at high road temperatures; easily blend with bitumen and its is readily available, he said. Besides, the natural rubber modified bitumen (NRMB) has superior properties in terms of penetration, softening point and elastic recovery, less affected by temperature fluctuations and improves skid resistance thereby enhancing road safety, he said.
NRMB roads are more resistant to brittleness, less rutting or permanent deformation and more resistant to fatigue and conserves energy.
Roads surfaced with NRMB provide at least 50 per cent more service life than ordinary bitumen roads while the price of NRMB is 7 per cent more than that of the other. Besides, experience has shown that the NRMB roads could cut maintenance cost by 30 per cent. Also, the fuel consumption of vehicles plying on such roads is expected to be reduced by 10 per cent, he said.
Meanwhile, according to two experts with the Rubber Board, different types of bitumen as polymer-modified bitumen (PMB), NRMB, and crum rubber-modified bitumen (CRMB) are being used in the country in road construction, especially in highways and the performance is observed to be promising.
Based on this, the Indian Road Congress (IRC) has approved the use of modified bitumen and consequently the Union Ministry of Road Transport and Highways has already issued guidelines and instructions for its use in highway construction. The preliminary performance study of these roads conducted by the Central Rod Research Institute (CRRI), New Delhi, is observed to be promising. ``There is positive response from the National Highways Authority of India to use NRMB/CRMB for their renewal works and development projects,'' they said Resources - http://www.bitumenexchange.com , http://bitumenexporter.blogspot.com. http://www.benzeneinternational.com
Improving Bitumen Performance
The actual performance of the bitumen is just one part of the total performance of a bitumen / aggregate mixture. This depends on a number of factors including the design of the mixture, the way it was mixed and how it was laid and compacted. As bitumen is an integral part of the total mix, advice on how to avoid and correct errors would need to cover many factors and types of mixture.
It is possible to add some guidelines to optimize the performance of bitumen, mainly in hot bitumen/aggregate mixtures, based on the knowledge of bitumen itself.
Tips
Minimize the time during which hot bitumen is exposed to air. Bitumen hardens and loses some of its adhesive property when it is exposed to a combination of air and heat.
Bitumen shall be kept dry and away from contamination by water at all times. When it comes into contact with water it will foam.
Keep bitumen within the range of temperatures recommended for the type and grade. Bitumen solidifies as it cools and becomes unworkable, and the viscosity may increase if it is overheated. It is sensible to use bitumen at the lowest temperature that will permit it to be mixed, transported and compacted but in any case the maximum storage temperature relating to the grade should not be exceeded during the mixing process.
Temperature control is a major factor in the quality control of a bitumen / aggregate mixture. Avoid contaminating the bitumen, particularly with petroleum based solvents that reduce the Flashpoint and the viscosity and increase the penetration.
Just 0.1% diesel oil in a bitumen / aggregate mixture can lower the flash point and increase the penetration significantly.
Stability is an essential quality in the performance of a bitumen / aggregate mixture. it depends on friction and cohesion within the mixture. Too much bitumen actually acts as a lubricant for the aggregate particles, reducing friction and therefore the mixture's stability.
The cohesion or internal binding force in the mixture increases as the proportion of bitumen in the mixture is increased, until it reaches the optimum. if the amount of bitumen is increased further, stability decreases. it is therefore essential to ensure that the optimum proportion of bitumen is used in any mixture.
Finished mix should be frequently observed. Early warning signs that further checks should be made: If the distribution of bitumen on the aggregate is not uniform, the temperaturein the mixing operation was too low If the mixture looks stiff & dull rather than black and shiny there may be toolittle bitumen in the mixture If the mix lies slumped on the floor ,there may be too much bitumen in it.Blue smoke coming from the mix can indicate overheatingSteam coming from the mixture indicates the presence of too much moisture. Resources - http://www.bitumenexchange.com, http://bitumenexporter.blogspot.com , http://www.benzeneinternational.com
Adding Colour to Bitumen
Bitumen manufacturing exploits the advanced technology available to the oil industry for the development and quality control of petroleum products. Its application is leading to the establishment of new levels of understanding of bitumen's qualities and its potential advantages to end-users. The use of gas chromatography with electronic measurement apparatus to identify the chemical composition of bitumen made from various feedstock, and the correlation of this information with measurements of their road performance, is one such example of the practical benefits of this work.
The continual international increases in road traffic, particularly heavy freight -carrying vehicles, and the cost of maintaining existing highways and constructing new ones have brought new demands from bitumen users. They want the bitumen of the future to include specific improvements to their characteristics, particularly in the following sectors:Resistance to degradation at high temperaturesImproved ageing, i.e. resistance to degradation with timeImproved workability, allowing road courses to be laid under a wider range of temperatures and weather conditions so that the effective season for roadwork isextended.Resistance to cracking and deformationTolerance towards poor workmanshipIncreased adhesion to minerals
An example of the results of the work is the marketing of one of the first modified bitumen incorporating an elastic-thermoplastic copolymer. The result is a hard or semi-hard binder with an enhanced plasticity range, excellent adhesion to aggregates and enhanced fatigue and deformation characteristics. In common with other products of this type, it requires a specialized blending plant.
Colored bitumen offer great scope for imaginative application where there is a need to differentiate surfaces according to their use or to have a surface in harmony with its environment. They may be divided into two distinct types.
The first type comprises bitumen that have been specially prepared by selecting feedstock with a low proportion of asphaltene. Pigments are then mixed into the bitumen. The result is a colored bitumen where the colors are muted by the presence of asphaltenes. This limits their application to a certain extent.
The second type may accurately be described as translucent binders to which colors are added. They perform the same function as bitumen and can be made successfully in a broad range of colors, but they are not made of the same material as conventional bitumen.
The following article proves that Asbestos, which is a banned substance has found its way to the road.
Only the Bitumen Pitch from Bahrain has high asphaltine content ( around 15%) and not sure how it enters into the australian markets.
Pls read on..
The NSW Department of Environment and Climate Change and Water (DECCW) have confirmed the presence of asbestos in a sample of road base taken from Plains Station Road in Ewingar.
The sample was taken by Ewingar resident Michael Mizzi after his friend, geology student Jeff Finlay, told him that some of the rock used in road base in the area contained asbestos.
“I started looking into it on the internet and found that there were two types of asbestos and both of them were considered to be carcinogenic,” Mr Mizzi said.
He collected three random samples from along Plains Station Road and took one to Page MP Janelle Saffin’s office and one to Southern Cross University for testing. It was sent to a laboratory in Sydney for analysis and came back positive for chrysotile asbestos.
DECCW were called and further testing was done confirming the presence of the material. In an email to Mr Mizzi, Jon Keats from DECCW said: “We recently undertook an inspection of Plains Station Road with Council officers and collected samples for analysis. The results confirmed the presence of chrysotile asbestos in a number of samples, although no respirable fibres were detected. Council met yesterday afternoon with DECCW to discuss its proposed response to this issue. Council advised that it would also be liaising with and seeking advice from the Workcover Authority and NSW Health. DECCW will be monitoring Council’s response to this issue.”
Mr Mizzi believes Council should call a public meeting and alert residents as to what the dangers are.
Clarence Valley Council general manager Stuart McPherson said they were doing more tests to determine exactly where the material was.
“We believe the vast majority of the material is at a couple of bridge projects and it has also been detected on some heavy patching sites on Plains Station Road and Bulldog Road,” he said. “We are negotiating with state agencies that have regulatory powers in this area, particularly the EPA, and are hoping to have resolutions about a process that we will undertake to resolve the issues shortly.”
Mr McPherson said Council would be sealing the roads with bitumen where the patching work had been done in the short term.
“We will have more permanent rectification measures that we’ll undertake following negotiations with the ETA,” he said.
A chemistry professor from Tamil Nadu has discovered that a marriage of convenience between hot bitumen and molten plastic waste could be the way towards what Lalu Prasad had once dreamt for Bihar’s roads.
R. Vasudevan’s finding, which promises to solve the twin problems of battered roads and plastic waste, has received official recognition, with the Union rural development ministry issuing guidelines for laying rural roads using plastic waste.
Civic bodies in Tamil Nadu and the state’s highway department have already laid more than 750km of plastic roads and are adding more based on the process developed by Vasudevan, head of chemistry at Thiagaraja Engineering College, Madurai.
“It’s a simple procedure where plastic waste is mixed with hot bitumen before it is laid. Since plastic waste like cups, carry bags, etc, are heated only up to 170°C, they form a molten paste and get mixed with the bitumen,” said Vasudevan, who has given the patent of the process to the college.
He added: “Since the waste is not incinerated, which happens at 690°C, no toxic gases are released. As only non-chloride polymer waste is used, chlorine seepage into the ground is also avoided.”
Adding plastic reinforces a road in three ways. It increases the road’s load-bearing capacity, makes it more resistant to heat especially during summers, and prevents rainwater from seeping down. The third factor ensures durability, since water is the main enemy of bitumen-based roads.
“The life of the road will be prolonged three to four times provided there are no cuts and patchwork after it is laid,” Vasudevan said.
Performance studies on the roads built with plastic waste in Tamil Nadu indicate “satisfactory performance with good skid resistance, good texture value, stronger and less amount of progressive unevenness over a period of time”, say the guidelines issued by the National Rural Roads Development Agency, an arm of the Union rural development ministry.
The ministry recommends the use of polyfilms with thickness up to 60 microns, hard and soft foams and laminated polymer with thickness up to 60 microns. However, polyvinyl chloride sheets (flex sheets) should not be used. The process of coating the aggregate (tar and granite mixture) with molten (waste) plastic does not require machinery.
Modifying bitumen with shredded plastic waste raises the cost by Rs 2,500 per tonne, but this is offset by the need for less bitumen, better performance and environmental conservation, the guidelines say. They even ask local bodies to contact Vasudevan (0452-2482240) for further advice.
Vasudevan said the local bodies could initially source the plastic waste from their own dumps, since a 10x10-metre road needs just 1.7kg of plastic. Two lakh tonnes of plastic items are sold every month in Tamil Nadu alone, of which 40 per cent is recycled and 10 per cent gets into garbage. Source- The Telegraph , www.bitumenexchange.comhttp://bitumenexporter.blogspot.com
Viscosity Vs Penetration
Bharat Petroleum Corporation Ltd today became the first Oil Marketing Company to introduce Viscosity Grade Bitumen in the India.
The product was officially launched in the Southern markets at a formal function here by releasing the product catalogue which was handed over by D M Reddy, Executive Director (I&C), BPCL, Mumbai, to T K Jose, Managing Director of the Roads and Bridges Development Corporation of Kerala ltd.
Kochi Refinery Executive Director, E Nandakumar, and other senior officials from BPCL and Kerala Public Works Department were also present, a BPCL-KRL press release said.
The BIS hasissued IS 73:2006 specification for Viscosity Grade Paving Bitumen which supersedes the earlier specification IS 73:1992 for Penetration Grade Paving Bitumen.
Viscosity Grade Paving Bitumen replaces the traditional penetration grade bitumen and is designed to take care of pavement distress at lowest temperature (responsible for cracking) and at maximum service temperature (responsible for rutting).
Besides, the refinery is also marketing NRMB (Natural Rubber Mixed Bitumen).The roads laid with this product lasts for longer period compared to traditional bitumen. Emulsion Grades, Slow setting and Rapid setting are also specialties of BPCL which can be used even during rainy season for maintenance purposes, the release said. Resources- www.bitumenexchange.comhttp://bitumenexporter.blogspot.com
