4. Bitumen modification

Bitumen exhibits viscoelastic properties as rheological structure. Bitumen, which plays a major role in many parameters of road performance, mainly cracking and permanent deformation resistance, also causes viscoelastic properties of asphalt mixtures. Generally, the amount of deformation in asphalt coating varies depending on the loading time and the temperature value.

The behavior of bitumen affected by static and dynamic loads is shown in Figure 3.

Permanent deformation (creeping), cracking (thermal or fatigue), moisture damage are the most common types of degradation in flexible coatings. Shortening the service life of road coverings under increasing traffic load has necessitated modification of bitumen. In recent years, based on polymers, the use of highly modified bituminous blends and mixtures has been increasing. As polymer additives and non-polymer additives as shown in Table 2.

Usage purposes of modified bitumen applications:

Figure 3. The behavior of bitumen affected by static load (a) and dynamic load (b) [27].

d. Antioxidants Zinc and lead antioxidants, phenolics

Organo carbon compositions

Epoxy resins

(SBS),

(IIR)

III. Chemical reaction modification Additive reaction (bitumen + monomer)

Polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC),

Synthetic butadiene copolymer (SBR), Styrene-butadiene styrene copolymer

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Ethylene prokplendien harmoliper (EPDM), Isobutene isoprene copolymer

Polystyrene (PS), ethylene vinyl acetate (EVA)

Polyester, fibers, polypropylene fibers

Vulcanization (bitumen + sulfur) Nitrogen reaction (bitumen + nitric acid)

f. Others Organo manganese compositions

Modification types Specimens

e. Organo-metal compounds Amines

a. Filler Clay, black carbon, fly ash b. Anti-peel additives Organic Amines and Amids

c. Expander (Extendents) Lignin and sulfur

I. Modification with non-polymer additive

II. Modification with polymer additives

a. Plastics

4. Fibers

1. Thermoplastics 2. Thermosets b. Elastomers 1. Natural Rubbers 2. Artificial Elastomers 3. Processed Rubbers

• Control of fatigue cracks,

Table 2. Bitumen modification types [29].

• Water impermeability,

Figure 3. The behavior of bitumen affected by static load (a) and dynamic load (b) [27].


#### Table 2. Bitumen modification types [29].

Usage purposes of modified bitumen applications:


4. Bitumen modification

24 Modified Asphalt

Bitumen exhibits viscoelastic properties as rheological structure. Bitumen, which plays a major role in many parameters of road performance, mainly cracking and permanent deformation resistance, also causes viscoelastic properties of asphalt mixtures. Generally, the amount of deformation in asphalt coating varies depending on the loading time and the temperature value.

Permanent deformation (creeping), cracking (thermal or fatigue), moisture damage are the most common types of degradation in flexible coatings. Shortening the service life of road coverings under increasing traffic load has necessitated modification of bitumen. In recent years, based on polymers, the use of highly modified bituminous blends and mixtures has been increasing. As polymer additives and non-polymer additives as shown in Table 2.

The behavior of bitumen affected by static and dynamic loads is shown in Figure 3.

Figure 2. Illustration of asphalt aging process due to volatilization, oxidation, absorption and adsorption [28].

Table 1. List of individual factors and conjoint factors that affect asphalt aging [28].


Additives used in the modification of bituminous and bituminous mixtures and the benefits provided according to their shape of deterioration are shown in Table 3.

Molecular structure of SBS additives is illustrated in Figure 5.

Figure 6 is indicated a three-dimensional view of asphalt-coated SBS molecules and the SBS modified bitumen structure consisting of asphaltic cell form and styrene butadiene bonds.

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When the structure of SBS is examined, the following conclusions can be drawn: • The polystyrene crowlings gives strength by forming physical cross-links.

• At 100C, the polymer becomes fluid and the three-dimensional network structure recurs. Since the material is a thermoplastic elastomer, it does not lose anything in its heating and

Figure 6. Three-dimensional appearance of asphalt-coated SBS molecules bond structure of SBS coated asphalt film

In this study, initially, some conventional tests were applied. The properties of bitumen and aggregates to be used in bituminous hot blends have been examined. In the performance tests; core samples were taken different time in 1 year period (1st, 4th, 8th and 12th months) and tested in Figure 7. Core samples achieved from the implementation of asphalt pavement which are prepared with SBS modified and neat bitumen of the asphalt pavement. When taking the

• The polybutadiene bridges provide elasticity and flexibility.

• It maintains its characteristic between 40C and + 80C.

cooling properties.

[30, 32].

Figure 5. SBS molecular structure [31].

6. Materials and methodology


Table 3. Benefits of different types of modifications [27].
