production tests aging of bitumen and modified Bitumen

Presentation on BITUMEN

By:-Vinay GautamSurajPraveenNarayanaAbhijeetBhupalKaushlendra

BITUMEN

“A viscous liquid, or a solid, consisting essentially of hydrocarbons and their derivatives, which is soluble in trichloro - ethylene and is substantially nonvolatile and softens gradually when heated.”

“It is black or brown in colour & possesses waterproofingand adhesive properties.”

PRODUCTION OF BITUMEN Bitumen is manufactured from crude oil. Bitumen is obtained as the last residue in fractional distillation of crude petroleum.The heaviest material obtained from the fractional distillation process is further treated and blended to make different grades of paving grade bitumen

Types of Bituminous Materials

Types of Bitumen

•Tar and Pitch:

Most of the tar and pitch used in construction is made by the distillation of coal.

Tar is used to saturate felt paper and coated kraft paper to produce a waterproof membrane.

Coal – tar pitch oxidizes quite rapidly when exposed to ultra violet rays of the sun.

Types of Bitumen’s•Asphalt

A large percentage of the asphalt used results from the refining of crude oils

There are three main groups of asphalt products produced from straight run asphalts

Asphalt

• Hot asphalt- those soften by heat

Hot asphalt can be used directly or it can be processed further to produce a harder material

Hot asphalts have good resistance to the transmission of water and water vapor when they are applied to dry surfaces and the heating process is controlled

Hot asphalts bond poorly to damp or wet surfaces, have relatively poor flexibility, oxidize under the sun’s rays and are brittle at low temperatures

Asphalt

• Cut back asphalts – those dissolved in mineral solvents

Cutback asphalts are of three types

Straight run asphalt and solvent

Heavily filled cutback made by adding a large amount of filler and fiber to asphalt cut with solvent

Primer type cutback asphalt in solution with no filler or fiber

Asphalt• Emulsion asphalts – those dispensed

or suspended in a water base

• Three types

Soap type in which soap is used as the emulsifier

Clay modified soap type – clay and soap are used as emulsifier

Clay based type

• Advantages

Easy to handle

No heating is required

Good bonding to damp or wet surfaces

BITUMINOUS TEST

• PENETRATION TEST

• DUCTLITY TEST

• VISCOSITY TEST

• SOFTNING POINT TEST

• FLASH AND FIRE POINT TEST

• SPECIFIC GRAVITY TEST

• SOLUBILITY TEST

• FLOAT TEST

• BINDER CONTENT TEST

PENETRATION TEST

AIM OF THE PENETRATION TEST:

To find out the hardness or softness of bitumen.

To determine the consistency of bituminous material

Grade of bitumen.

Apparatus required are

a) penetrometer

b) water bath

c) thermometer

The test carried out with a standard penetrometer with a needle loaded with 100 gms,

PENETRATION TEST

PENETRATION TEST contd………

Procedure:

Soften the bitumen by heating (between 75 and 100oC). Stir it thoroughly to remove air bubbles and water.

Pour it into a mould completely and level it.

Cool it at an atmospheric temperature of 15 to 30oC for 11/2 hours.

Maintain test temperature as 25 degree Celsius

Keep the container on the stand of the penetration apparatus

Clean the needle with benzene, &dry it

Adjust the needle to make contact with the surface of the sample

Adjust the dial reading to zero and note the initial reading

PENETRATION TEST

The needle is then released and allowed to penetrate into the sample under the full action of the load.

The penetration at the end of time 5 seconds is measured .i.e final reading

Difference of final &initial reading gives penetration value

Repeat the steps thrice.

Take the mean value & which becomes the penetration value of bitumen.

PENETRATION TEST

PENETRATION TEST

The bitumen grade is specified in terms of penetration value.

The bitumen of grade 80/100 means that the range of penetration value of the material is between 80 and 100.

Depends upon the climatic conditions and type of construction, bitumen are used.

IRC RECOMMANDATIONS

• Bitumen grades

a) 30/40,

b) 60/70,and

c) 80/100

• Hot climates -Lower penetration grades of bitumen are preferred.

• Cold climate - higher penetration grades of bitumen are preferred.

RECOMMANDED VALUES As per IS 73-2006

GRADES VG 10 VG20 VG30 VG40

Penetration at 25”C,

80-100 60-80 50-70 40-60

DUCTILITY TEST

Aim:• To measure the ductility of a given sample of bitumen

• To determine the suitability of bitumen for its use in road construction

The apparatus required for this test:i) Standard mould (briquette mould)ii) Water bathiii) Testing machineiv) Thermometer – Range 0 to 44oC, Graduation 0.2oC

PROCEDURE:

(i) Melt the bituminous test material completely at a temperature of 75°C to 100° C above the approximate softening point until it becomes thoroughly fluid.

DUCTILITY TEST

ii) Assemble the mould on a brass plate and in order to prevent the material under test from sticking, thoroughly coat the surface of the plate and the interior surfaces of the sides of the mould with a mixture of equal parts of glycerin and dextrin.

iii) pour the sample of bitumen into the mould and level it using straight hot knife

iv) After about 30-40 minutes, keep the plate assembly along with the sample in a water bath. Maintain the temperature of the water bath at 27° C for half an hour.

(v) Remove the sample and mould assembly from the water bath and trim the specimen by leveling the surface using a hot knife.

DUCTLITY TEST

DUCTILITY TEST

DUCTILITY TEST contd……

vi)remove the sides of the mould.

vii) Hook the clips carefully on the machine without causing any initial strain. Adjust the pointer to read zero.

viii) Start the machine and pull clips horizontally at a speed of 50 mm per minute.

ix) Note the distance at which the bitumen thread of specimen breaks.

Mean of two observations rounded to nearest whole number is ductility value.

Limiting values

bitumen grades ductility ( cm)

S45 &above 75

S35 50

A65-200 15

for viscosity graded bitumen

GRADES VG10 VG20 VG30 VG40

Ductility at 25”C, cm

75 50 40 25

SOFTNING POINT TEST

• Aim:

To determine the softening point of bitumen.

• The apparatus required for this test :-i)Steel balls-two numbers each of 9.5 mm diameter weighing 3.5 ± 0.05 g.

ii) Brass rings-two numbers each having depth of 6.4 mm. The inside diameter at bottom and top is 15.9mm and 17.5 mm respectively.

iii) Bath-heat resistant glass beaker not less than 85 mm in diameter &1220mm deep. iii) Thermometer – Low Range : -2 to 80oC, Graduation 0.2oC –

SOFTNING POINT TEST contd..

Procedure The sample should be just sufficient to fill the ring. The

excess sample should be cut off by a knife.

Heat the material to a temperature between 75o – 100oC above its softening point, stir until, it is completely fluid and free from air bubbles and water

SOFTNING POINT TEST contd..

• If necessary filter it through IS sieve 30.

• Heat the rings and apply glycerin. Fill the material in it and cool it for 30 minutes

• Assemble the apparatus with the rings, thermometer and ball guides in position.

• After cooling for 30 minutes in air, level the material in the ring by removing the excess with a warmed, sharp knife.

SOFTNING POINT TEST contd..

• Fill the container with distilled water to a height of 50mm above the upper surface of the rings. The starting temperature should be 5oC

• With the help of a stirrer, stir the liquid and apply heat to the beaker at a temperature of 5.0 ± 0.5oC per minute.

SOFTNING POINT TEST contd..

• Apply heat to the bath and stir the liquid so that the temperature rises at a uniform rate of 5±0.5oC per minute

• Record the temperature at which the ball touches the bottom, which is nothing but the softening point of that material.

Significance of softening point test

• Softening Point test is a very important test as it is a fair indicator of melting properties of bitumen.

• Bitumen with lower softening point tend to melt on the road in summer and start flowing under the impact of temperature and traffic

• Therefore it can be concluded that bitumens with higher softening point melt at higher temperatures and have better rutting resistance

RECCOMMENDED VALUES

GRADES VG10 VG20 VG30 VG40

Softening point(degree Celsius)

40 45 47 50

VISCOCITY TEST

• Its defined as fluid property of the material as resistance to flow

• APPARATUS:

Tar viscometer, cup, valve, receiver, thermometer etc.

VISCOCITY TEST

RECOMMENDED VALUES: 

Bitumen grades SC.MC,RC

1 2 3

Orifice size (mm) 10 10 10

Test Temperatures(°C)

25 40 40

Viscosity Ranges (SEC)

10-20 25-75 14-45

Significance of viscosity test

• Too viscous bitumen would result in inadequate and non-uniform coating of the aggregates.

• Very low viscosity would again result in inadequate coating as the bitumen will tend to bleed.  

• Therefore viscosity at 135*C is a true reflection of the quality of bond that is likely to be formed with the aggregate.

Flash and Fire point test

• Flash point:-The flash point of a material is the lowest temperature at which the application of test flame causes the vapours from the material to momentarily catch fire in the form of a flash under specified conditions of the test.

• Fire point:-The fire point is the lowest temperature at which the application of test flame causes the material to ignite and burn at least for 5 seconds under specified conditions of the test.

• Significance of flash and fire point:-

for safety point of view this tests are conducted, if bitumen is heated beyond flash point it catches fire ,therefore utmost care is taken to see that heating is limited to a temperature well below the flash point and used along the aggregates for the construction of pavements.

Specific gravity test

• This test is done to determine the specific gravity of semi-solid bitumen road tars. The principle is that it is the ratio of mass of a given volume of bitumen to the mass of an equal volume of water, both taken at a specified temperature.

• Apparatus :-

i) Specific gravity bottles of 50ml capacity ii) Water bath iii) Bath thermometer – Range 0 to 44oC, Graduation 0.2oC

•  

Solubility test

• Pure bitumen is fully soluble in carbon disulphide and carbon tetrachloride. If some quantity remains undissolved it exhibits the quantity of inert mineral present in the bitumen. Bitumen should be soluble in carbon disulphide at least 99%.

Float test

• The Float Test is used as a measure of consistency for distillation residues. Residue from the emulsion is cast in a tapered collar, and then it is allowed to float in a testing bath at a specified temperature. The time, in seconds, between placing the apparatus on the water and the water breaking through the material shall be taken as a measure of the consistency of the material under examination.

Significance of float test:-

The float value is one of the prime characteristics for identifying "high float" asphalt emulsions. This high float characteristics enables softer asphalt materials to remain in place on the roadway without running off.

Impact test on Aggregate Aim: To determine the aggregate impact value of given aggregates.

Apparatus required:Impact testing machine, cylinder, tamping rod, IS Sieve 12.5mm, 10mm and 2.36mm,Weight balance.

IMPACT TEST

Procedure

• The test sample consists of aggregates passing 12.5mm sieve and retained on 10mm sieve and dried in an oven for 4 hours at a temperature of 100oC to 110oC.

• The aggregates are filled up to about 1/3 full in the cylindrical measure and tamped 25 times with rounded end of the tamping rod.

IMPACT TEST Contd….

• The rest of the cylindrical measure is filled by two layers and each layer being tamped 25 times.

• The overflow of aggregates in cylindrically measure is cut off by tamping rod using it has a straight edge.

• Then the entire aggregate sample in a measuring cylinder is weighed nearing to 0.01gm

IMPACT TEST contd..

• The aggregates from the cylindrical measure are carefully transferred into the cup which is firmly fixed in position on the base plate of machine. Then it is tamped 25 times.

• The hammer is raised until its lower face is 38cm above the upper surface of aggregate in the cup and allowed to fall freely on the aggregates.

• The test sample is subjected to a total of 15 such blows each being delivered at an interval of not less than one second

IMPACT TEST contd..

• The crushed aggregate is than removed from the cup and the whole of it is sieved on 2.366mm sieve until no significant amount passes.

• The fraction passing the sieve is weighed accurate to 0.1gm. Repeat the above steps with other fresh sample.

• Let the original weight of the oven dry sample be W1gm and the weight of fraction passing 2.36mm IS sieve be W2gm.

• Then aggregate impact value is expressed as the % of fines formed in terms of the total weight of the sample.

Aggregate impact valueS.NO

NATURE OF STONE AGGREGATE VALUE

1 Exceptionally Strong < 10%

2 Strong 10% to 20 %

3 Satisfactory 20% to 30%

4 Weak for Road Surfacing >30%

AGING OF BITUMEN

• The physical and rheological properties of bitumen change with time. It may become harder or less elastic. Bitumen properties change over time on exposure to high temperature and the atmosphere. This process is referred to as ageing.

• Based on hardening or stiffening of asphalt material

1. short-term ageing.

2. long-term ageing.

1. Short-term ageing

This occurs when bitumen is mixed with hot aggregates i.e., during production and construction .

2.Long-term ageing

This occurs after HMA pavement construction and is generally due to environmental exposure and loading i.e., during the life of the pavement

Factors influencing bitumen Aging

1.Oxidation

2. Loss of volatiles

3. Steric or physical hardening 4. Exudative hardening …. Time, Heat, Oxygen, Sunlight

• OXIDATION: The degree of oxidation is highly dependent on the temperature, time and the thickness of bitumen film. Ageing produces polar species that can form singles or multiple structures

• LOSS OF VOLATILES :The evaporation of volatile component depends mainly upon temperature and exposure conditions.

• PHYSICAL HARDENING: It is strongly influenced by aggregate-bitumen interactions. Directly after cooling, asphalt sometimes appears to be soft as if it was still warm and a few days later, the asphalt seems to have matured. This phenomenon is called setting and is caused by slow physical hardening.

• EXUDATIVE HARDENING :Exudative hardening results from the movement of oily components that exude from the bitumen into the mineral aggregate

EFFECT OF DIFFERENT TYPES OF AGING ON BITUMEN PERFORMANCE

• EFFECT OF THERMAL AND ULTRAVIOLET AGING

• Consider three types of base bitumen from different sources with the same penetration grade are taken as A ,B ,C.

DEGRADATION RATES OF PHYSICAL INDICES OF AGED BITUMEN

TESTS ON AGING OF BITUMENThin film oven test (ASTM D1754)

Simulates short-term ageing by heating a film of bitumen in an oven for 5 hours at 1630C

Rolling thin film oven test(ASTM D2872)

Simulates short-term ageing by heating a moving film of

bitumen in an oven for 85 minutes at 1630C

Pressure aging vessel (ASTM D6521)

simulate the effects of long-term bitumen ageing that occurs as a result of 5 to 10 years HMA pavement service

REJUVENATION TREATMENT

• Replace the oils lost and rebalance the bitumen composition

• The controlling factor in rejuvenation is diffusion, to ensure a positive result, the level of diffusion must be controlled by careful choice of rejuvenator and the delivery method.

Asphalt Rejuvenation, Asphalt Rejuvenator - Seal Coating, Large Parking Lots 00_00_32-00_01_13.mp4

Modified bitumen

• Modified Bitumen is a highly specialized blend of bitumen with high quality polymer which is manufactured under carefully controlled conditions in a “State of Art” plant.

• Modified Bitumen is an exceptionally versatile product with enhanced properties that makes it suitable for wearing course application under special conditions like high rainfall and high traffic areas

Advantages of Modified Bitumen:

Lower susceptibility to temperature variations.

Higher resistance to deformation/wear and tear.

Better adhesion between aggregates and binder.

Increase in fatigue life.

Resistance in low temperature cracking.

Better age resistance properties.

Types of Modified Bitumen:

A variety of additives are used for modification of Bitumen.

The degree of modification depends on type of Modifier, its dose and nature of Bitumen.

The most commonly used Modifiers are:

Synthetic Polymers

Plastomeric Thermoplastics

Low Density Polyethylene(LDPE)

Ethylene Vinyl Acetate

Elastomeric Thermoplastics

Styrene Isoprene Styrene (SIS)

Styrene Butadiene Styrene Block Copolymer

 Natural Rubber

Latex Powder

Rubber Powder

Crumb Rubber

Crumb Rubber without additives

Crumb Rubber with additives

Cost Benefit Analysis:

Since other components of the cost of construction remains same except for the binder, the overall increase in the cost of construction is approx. 15-25%.

However, the field trials have proved that frequency of overlaying can be minimized and the maintenance cost can be reduced to about 22-30% excluding the cost of interest, safety and comfort to the road user.

Fatigue performance of bituminous mix

•It is phenomenon of fracture under repeated cyclic or fluctuating load• it is defined as no. of repetitions for which the initial stress or strain changes by arbitrary factor.

Fatigue test•A rectangular sample of bituminous mix is placed on simple support and repetitive load is applied to the sample, and sample is monitored till failure.

• Two cyclic loading is applied of equal magnitude P, (separated by 1/3rd of the length of beam.)

• Test is conducted under two types of controlled loading , namely controlled stress amplitude and controlled strain amplitude

Fatigue testing equipment

Pic source :- ASTM D7460-10

Fatigue performance of bituminous mix

The general expression for fatigue test result on bituminous mix is given as Nf=k1(1/ɛt)k2(1/Ed)k3

Where ,• Nf =number of load applicable to failure

• Ed = dynamic modulus of beam

• K1 ,k2 , k3 = regression constant

Conclusion:- The fatigue life of the mix for a given level of tensile strain is higher if the stiffness modulus E of the mix is low. Thus , bituminous mixes with softer grade of bitumen, are expected to have better fatigue life.

Laboratory fatigue curve on bituminous mix

References:• Influence of Bitumen Ageing on Asphalt Quality, Comparison Between

Bitumen and asphalt aging ;research paper by Tahirou Moustapha

• Aging of bitumen Tan yi-qiu, Wang Jia-Ni1, Feng Zhong-Liang2 and Zhou Xing , (2005). Influence and mechanism of ultraviolet aging on bitumen performance.

• The Shell Bitumen Handbook ,By John Read, David Whiteoak