Bituminous Materials & Bitumen
- Bituminous materials,classification and various terms used related to tar and bitumen.
- uses and applications of different bituminous materials in highway construction,
- origin and preparation of different grades of bitumen and tar.
- the rheology of bituminous binders,adhesion,failures,weathering of bituminous road.
- material admixtures,rubber,tar.
- introduction to recent development in highway materials
- growth of a country largely depends upon its efficient transportation system.
- well developed means of transportation is the lifeline of a country.
- transportation contributes to the economic,social,industrial and cultural development of the country.
- highways, railways, water ways, air ways are different modes of transportation
- Road transport is most interesting, versatile,flexible.
Major Factors Responsible For Failure Of Roads.
- Overloaded commercial vehicles.
- Improper design of roads.
- Improper construction of roads.
- Improper specifications.
- Drainage,and soil sub-grade conditions.
- Aging of bitumen.
Bitumen is a primary engineering material,due to its low cost as compared to other binding materials it is used in relatively thick films to provide protective film against corrosive influences and weather.Bitumen is a dense viscous material,dark black or brown in color,used as a binding and waterproofing material.
Bitumen – uses
- for paving roads.
- for manufacturing of roofing felt.
- for moisture proof and laminated packing material.
- for coating on roofs,walls and floors.
- including these there are 250 known uses of bitumen.
Bitumen tests are specified to recognize its quality. Based on its application each test can be
- Penetration ad viscosity tests for grading bitumen based on physical properties
- Ductility of bitumen measured the tolerate of asphalt against road traffic and temperature
- Softening point test is applicable to determine the start melting point
- For recognizing the quality and impurity of bitumen spot solubility and specific gravity is
- The amount of volatile content measured by loss on heating test
- Flash and fire point tests consider the hazards of air temperature conditions in the transportation and storage of bitumen
You can get acquainted with the goals and process of the most common bitumen tests by
reading the infographic below:
ORIGIN OF REFINERY BITUMEN
- Organic component of marine animals ,plant deposits mingled with and covered by sedimentary mineral matter the action over millions of yearsof bacterial attack,moderate heat,pressure and catalytic action of finely devided mineral particles has converted the fatty residue into crude petroleum.
- Bitumen is produced from selected crude oils.
- Preliminary distillation is normally carried out near oil fields
BITUMEN REFINERIES AND AGENCIES INVOLVED IN REFINERY WORKS
- MATHURA (U.P)
- HALDIA (W.B)
- BONGAINGAON (ASSAM)
- MUMBAI (MAHARASHTRA)
- KANDALA (GUJARAT)
- HINDUSTAN PETROLEUM
- INDIAN OIL COMPANY
- BHARAT PETROLEUM.
- HP,IOC,BP,IBP ETC.
Requirement Of Bitumen Or Properties
- the bitumen should possess adequate viscosity while mixing and compaction.
- it should not be highly temperature susceptible.
- in the presence of water it should not strip off from aggregate.
Limitations of Conventional Bitumen
- Brittleness at Low Temperature
- Becomes Soft In Hot Climatic Conditions
- High Temperature Susceptibility
- Susceptible To Deformation (Rutting)
- Fatigue Failure (Cracking)
- Poor Adhesion
Members Of Bitumen Family
- ASPHALT:- when bitumen contains some inert material or mineral.
- LAKE ASPHALT, ROCK ASPHALT.
- LAKE ASPHALT:- IT IS FOUND IN WELL DEFINED SURFACE DEPOSITS IT CONTAINS:-
- BINDER – 54%.
- MINERAL MATTER – 36%.
- ORGANIC MATTER – 10%.
rock asphalt :-it is formed by the impregnation of calcareous rock,such as lime stone or sand stone.
- it contains about 12% of bitumen.
- tar:- it’s a viscous liquid obtained when natural organic materials such as wood and coal are carbonised or destructively distilled in the absence of air, wood tar, coal tar.
- five grades:- rt1 to rt5 .
- rt 1 has lowest & rt 5 has higest viscosity.
List Of Uses Of Different Grade Road Tar.
- RT 1 :- for surface painting under exceptionally cold weather conditions and on hill roads.
- RT 2 :- standard surface painting under normal Indian climatic condition.
- RT 3 :- surface paintings,renewal coats,premixing chips for top course.
- RT 4 :- premixing tar macadam in base course.
- RT 5 :- for grouting.
Comparison between bitumen & tar.
- Petroleum product.
- Soluble in cs2 & ccl4.
- Has better weather resisting properties.
- Less temperature susceptible.
- carbonation of coal or wood.
- Soluble in toluene.
- Inferior weather resisting properties.
- Highly temperature susceptible.
- cutback is defined as the bitumen ,the viscosity of which has been reduced by a volitile diluent,for surface dressing,bitumen macadam,and soil bitumen stabilization.available in 3 types.
- rapid curing :- naphtha and gasoline.
- medium curing :- kerosene.
- slow curing :- light oils.
- bitumen or refined tar broken up into fine globules and kept suspended in water, a small proportion of an emulsifier is used to facilitate the formation of dispersion,and to keep the globules in suspension.
- emulsifier usually adopted are:-
- soaps,surface active agents,and colloidal powders.
- Traditionally bitumen is regarded as a colloidal system which consist of high molecular weight asphaltene micelles & are dissolved in lower molecular weight oily medium called as maltenes.
- According to structure bitumen can be classified in two type :-
1) SOL Type or solution type.
2) GEL Type or gelatinous type.