modified bitumen for sale market
Bitumen is a material that has a dark brownish black hue and is primarily composed of malts and asphaltenes and is widely offered for sale in many countries. Asphalt preparation is one of the applications of bituminous adhesives.
An adhesive should, in general, be flexible enough to sustain permanent deformation and not flow at high temperatures. Bitumen modified polymers are utilized to change their natural rheological properties in order to attain appropriate mechanical qualities.
Extensive usage of plastics and rubber in different industries such as industry, agriculture, and even everyday living results in enormous polymer waste and environmental challenges.
New approaches were investigated in order to tackle this challenge.
As a result, both economically and environmentally, it is advantageous to employ waste polymers as bitumen-modifying polymers, so that the qualities of modified bitumen polymers of waste are similar to the features of modified bitumen polymers of first-hand polymers.
Bitumen's chemical structure, bituminous colloid structure, and physical and rheological properties are all intertwined. Any material that affects the chemical structure of bitumen changes its properties, and as a result, it can be a modifier.
Modified bitumen should have higher adhesion than pure bitumen, decreased thermal sensitivity in the service temperature range, and sufficient viscosity at execution temperature.
Furthermore, its sensitivity to loading time is minimal, and its resistance to plastic deformation, fatigue, and cryogenic cracks is strong. After age, its qualities are good for execution and service.
Polymer modification of bitumen
The chain of tiny molecules is repeated by adding polymers, and as a result, the pavement performance improves. Polymer-modified bitumen improves resistance to rutting, fatigue, and cryogenic cracks while decreasing damask and heat sensitivity.
As a result, polymer-modified bitumen is successfully employed in high-stress areas such as crossroads, airports, truck weighing zones, and race tracks. Polymeric bitumen has beneficial features such as increased elastic recovery, viscosity, softening point, adhesion, and flexibility.
Polymers used to accommodate bitumen are often classified as thermoplastic elastomers, plastomers, or reactive polymers [8, 9].
At low temperatures, thermoplastic elastomers often have greater elasticity against the pavement, but reactive polymers and plastomers increase hardness and strength against permanent deformations.
Because of the presence of operational groups, reactive polymers react with bitumen and have higher compatibility than the other two polymers.
Experience has shown that only a few polymers are compatible with bitumen. Industrial polymers used to alter bitumen are often classified into two types:
Copolymer ethylene vinyl acetate (EVA) is one of the most prevalent types of plastomers, and its category is determined by the percentage of vinyl acetate and its molecular weight (determined in terms of the melting temperature).
Copolymer styrene-block styrene-butadiene is a typical form of thermoplastic elastomer (SBS). These polymers are classed based on their styrene content, molecular weight, and linear or radial shape.
At high temperatures, bitumen can be mixed with a polymer of thermoplastic elastomers to produce three sorts of products:
Heterogeneous mixture: In this sort of mixture, polymers and bitumen are incompatible, resulting in the separation of combined components. This bitumen mixture lacks the necessary characteristics for pavement application.
Homogenous mixture: This mixture is totally homogeneous at the molecular level, indicating that bitumen and polymer are completely compatible. The oil in bitumen totally dissolves the polymer and destroys any inter-micromolecular connection.
In such a case, the bitumen is fully stable, and its qualities alter very little from the base bitumen, which increases viscosity. As a result, such a circumstance is undesirable.
A micro-heterogeneous mixture is made up of two distinct parts that are simply locked and clamped together. Such compatibility is important since it increases the characteristics of bitumen.
In this state, suitable polymer particles absorb the oil-based phase of the bitumen and swell to form a polymer phase distinct from residual bitumen components composed of heavier bitumen components such as oil, resin, and asphaltene.
Polymers of several sorts are employed in bitumen modification, each with its own modification method and features. Some of the most prevalent polymers employed in the alteration of bitumen characteristics have been examined in this section.
Styrene butadiene rubber (SBR)
SBR is a copolymer in which the monomers styrene and butadiene are unevenly linked in a polymeric chain dependent on their beginning percentages.
Because of the presence of thermoplastic styrene monomers between the layers of butadiene rubber monomers, this copolymer has high strength and is widely utilized in the tire industry.
Unfortunately, this rubber-inflated bitumen is not compatible with bitumen, so it cannot significantly improve bitumen properties.
Styrene butadiene styrene (SBS)
SBS is a block copolymer that increases the flexibility of bitumen. This polymer is one of the best bituminous modifying polymers for increasing bitumen properties, but it has certain economic and technical constraints.
However, SBS is the most commonly used modifier in the pavement after rubber powder.
Depending on the source of the base bitumen and the polymer, the morphology of the SBS and bitumen mix may vary. The phase is continuous in one of the bitumen states, and the SBS particles are scattered in the bitumen.
In the other states, the bitumen cells reside as a continuous phase in the polymer.
Bitumen and polymer continuous phases interlock in the third condition (high polymer concentration). In this state, a critical network forms between bitumen and polymer, increasing the mixture's complex shear modulus and thus its resistance to rutting.
Ethylene vinyl acetate (EVA)
As the percentage of EVA increases, the degree of penetration reduces and the softening point rises. This action is more pronounced in EVA which contains less vinyl acetate (VA).
Another study discovered that the chemical structure of bitumen has a decisive role in the physical qualities of polymer-modified bitumen in bitumen with a low proportion of EVA (bitumen matrix is dominating).
It considerably lowers the effect of bitumen chemical structure at large percentages of EVA (polymer matrix is dominating).
Bitumen modification with rubber powder (CRM)
A group of scientists examined the life-cycle cost of the pavement, including rubber powder and other modifiers, and concluded that using rubber powder to alter bitumen is cost-effective.
A US law was passed in 1991 that required the government to use rubber powder (5%) in roads built using state funds beginning in 1994. This figure should be raised to 20%.
Naturally, this law was later amended. Rubber is typically made from recycled tires. This decreases the amount of area required to replace worn tires.
The addition of natural rubber to bitumen raises the resistance of the asphalt mixture to rutting and increases its flexibility. On the other side, it is prone to delamination. Rubber powder is less compatible than bitumen due to its higher molecular weight.
Another common issue with natural rubber is the need for a higher temperature and more time to mix and disperse rubber in bitumen.
Despite the extensive investigation into the nature of the reaction of rubber and bitumen particles, the specific mechanism of this activity remains unknown.
Many researchers believe that after mixing melted pure bitumen with rubber powder, the polymer chains of the rubber powder absorb aromatic compounds from the pure bitumen. Powdered rubber particles soften and swell, increasing the viscosity of the rubber-bitumen combination.
Because of the physical and chemical reaction between bitumen and rubber powder particulates, the volume of powdered rubber particles increases two to three times its initial value.
If the temperature or mixing duration is high enough, the rubber particles disintegrate and disperse in the bitumen, and the polymeric chains are broken, reducing the mixture's viscosity.
Two aspects influence the properties of rubber-bitumen mixtures: swelling of powdered rubber particles and particle disintegration of powdered rubber.
Adding rubber powder to bitumen can raise one to three performance grades (PGs) above the operating temperature while lowering one to two PGs to lower temperatures, which is the operating temperature of bitumen.
As a result, the working temperature range of bitumen expands on both sides.
Other researchers noticed the same pattern at high working temperatures, although there was no change in the performance grade for rubber as the temperature rose.
The lower limit was limited in all cases by the creep rate result derived from the Bending Beam Rheometer or BBR test.
Overall, based on the findings of much research, it is possible to conclude that rubber powder enhances performance grade; however, in the case of low performance, the amount of improvement is strongly reliant on the bitumen, and the results vary depending on the bitumen utilized.
Finally, bitumen is one of the key components of asphalt mixtures, and it plays an important function in producing adhesion between particles in reaction to environmental parameters like temperature and traffic loading.
Because the vast majority of asphalt failures are caused by the deterioration of the rheological and chemical characteristics, as well as the heat sensitivities of the bitumen in asphalt, the materials science of road building has advanced through time.
Furthermore, the application of polymer modifiers has the potential to strengthen the bitumen in asphalt, which has led to improved asphalt resilience against rutting failures, permanent deformations in high temperatures, and increased fatigue life.
For more information on different kinds of bitumen in different grades and specifications, feel free to contact us. We are here to give you all the necessary information and guide you through the way.
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