Multigrade Asphalt Manufacture
ASPHALT AND CHEMISTRY
The chemistry of Asphalt is very complex. To manufacture blown and multigrade bitumen e-asfalto develop a process of chemical adjustment of asphaltic feedstocks (e.g: pen or viscosity grades) into top quality Asphalt for road and industrial applications:
The way the system works is to convert aromatic constituents containing hetero atoms into polar structural compounds, control of the reaction and the reactant ratios allows a predetermined asphalt composition to be produced.
Most crudes contain the basic building blocks to produce a suitable reactant feed for the process.
This includes, pen grade, viscosity grade, tube residues and extracts, vacuum residues and even waxy residues.
The process involves the chemical reaction, under tightly controlled conditions, of oxygen and hydrocarbons. Aromatic components and additives may be used, depending on the feedstocks, but normally no SIBS or rubber modification is necessary. The detail of the process is designed for the particular project.
The product produced depends on the reactant feeds available and the specifications to be met. When carried out with favorable feed stocks a MULTIGRADE Asphalt may be produced. In many cases the best MULTIGRADES can be produced from cheaper feedstocks than standard Asphalt.
Multigrade Asphalts made with compositional control:
|Resist Cracking at Low Temperature||Resist Deformation at High Temperature|
|Resist Aging||Optimize Adhesion|
|Optimize Emulsability||Improve Compatibility with Polymers of many types|
When manufactured in a correctly designed hotmixed asphalt MULTIGRADE asphalts will have:
|Improved Deformation Resistance||Excellent Fatigue Resistance|
|Excellent Moisture Resistance||Excellent Resistance to Oxidation|
The design of hot mixes should be carried out with a rational technique. The design methods now employ measurement of modulus, creep properties and fatigue propertiés by rational means. These outputs can be used in a mechanistic pavement design. Such a mechanistic pavement design can predict life of the final pavement. High Stiffness Modulus hotmixed Asphalt Pavements give longer life.
HIGH STIFFNESS MODULUS ASPHALT (HSMA) - A TREATMENT FOR TROPICAL CLIMATES
Hot mixed asphalt is a widely used material in pavement structures and surfaces. However it may fail prematurely if the design and materials are not right.
Hot mixes may fail due to:
|Deformation- rutting and shoving||Cold conditions|
|Cracking- by fatigue||Moisture damage|
|Poor quality base construction||Aging|
Deformation, in many hot and
tropical countries the use of soft grades of asphalt can lead to deformation in
the form of rutting and shoving. This can be avoided by use of MULTIGRADE
asphalts in thick layers.
Cracking may be due to poor base construction, inadequate pavement thickness for the traffic loadings or reflection of cracks from cracked bases ( such as concrete). This can be avoided by use of correct pavement design and the correct materials. Use of stiffer binders in the load bearing layers of the pavement will increase life.
Moisture Damage is caused by water getting into the hotmix via voids and displacing the Asphalt from the stone surface. This can be avoided by correct construction practices, particularly compaction, use of lime in the mixes and correct selection of asphalt, MULTIGRADE asphalts have higher compatibility with stone and are more difficult to displace as they create stiffer films.
Aging of Asphalt by oxidation leads to embrittlement. This is a function of the voids in the asphalt, the asphalt film thickness and the oxidation resistance of the asphalt. MULTIGRADE asphalts are easier to handle, giving better compaction, they are higher viscosity and hence can be applied in thicker films, and the composition balance increases the asphalt durability.
e-asphalt.com will be happy to quote special machines or proyect plant on receipt of details of composition of the product, etc.
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