MODIFICATION ASPHALT

ASBUTON (Asphalt Asbuton)

Buton rock asphalt or commonly known as asbuton was discovered in 1924 on Buton Island, Southeast Sulawesi. Asbuton began to be used in road paving since 1926. Based on existing data, asbuton has a deposit of about 677 million tons or the equivalent of 170 million tons of oil asphalt. Asbuton is the largest natural asphalt deposit in the world.

There are two main elements in Asbuton, namely asphalt (bitumen) and minerals. The use of these elements in paving work will affect the performance of the planned asphalt pavement.

There have been ups and downs in the use of Asbuton along with the need for asphalt materials and technological developments. Asbuton has been produced up to 500,000 tons / year. In the eighties, Asbuton's production had reached its lowest point. Meanwhile, in the nineties period, Asbuton produced was not optimal due to construction failures caused by the use of inappropriate technology. However, in accordance with the Ministry of Public Works Strategic Plan 2005-2009, Asbuton is set at 556,000 tons to be used for national road maintenance. In addition, around 550,000 km of provincial, district and city roads and other roads have the opportunity to apply Asbuton in its asphalt layer.

The types of Asbuton that have been produced both by fabrication and manually in recent years are:

1. Asbuton Item

The type of Asbuton based on grain size and asphalt content can be distinguished as shown in table 1.1.

Table 1.1 Asbuton Grain Types that have been produced

*) has been deprecated in 2004

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2. Pure Asbuton Full Extraction

This type of Asbuton is pure bitumen extracted by Asbuton using

several ways, including solvents or other methods such as using hot water technology. Extracted pure asbuton can be used directly as a substitute for hard asphalt or as an additive that will improve the characteristics of hard asphalt. Asbuton minerals are waste from the extraction process. Besides being used as a filter, it can also be used as a soil stabilizer.

3. Pre-Mixed Asbuton & nbsp; (pre-blended)

Asbuton pre-blended (pre-blended) is a combination of Asbuton grain results & nbsp; refine & nbsp; Asbuton with bitumen content 60% to 90% with asphalt 60 pen oil in a certain composition.

Asbuton of this type can be said to be modified oil asphalt, so that in the mixture it can be directly used to mix with aggregate.

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Advantages

A large deposit of Asbuton can guarantee the supply of asphalt demand. From the tests that have been carried out, the results of a mixture of asphalt added with asbuton produce a mixture of good quality asphalt with the following trends:

• Higher stability of Marshall mix asphalt
• Higher dynamic stability of asphalt mixes
• Increases construction life (from fatigue test results)
• More resistant to temperature changes
• Increased modulus value

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This tendency occurs because Asbuton contains high levels of aromatic and resinous ingredients, so that in the Asbuton mixture it has:

• Higher adhesion (anti & nbsp; stripping)
• High flexibility (fatigue life & nbsp; high)

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With these advantages, policy makers say that Asbuton:

• Suitable for high temperature (tropical) locations
• Suitable for & nbsp; heavy loaded highways.

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However, in implementing the policy of using asbuton to improve the quality of asphalt mixtures for pavements, strict quality control must be supported. This is because from several cases data was obtained that field implementers did not understand the effect of using asbuton in the asphalt mixture.

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Government policy on increasing the use of Asbuton will reduce imports of hard asphalt. This will have an impact on Asbuton's market conditions, making it more stable. This situation will be realized by optimizing the production stage and maintaining quality stability, so that the trust of Asbuton users will also increase. This condition can increase the economic value of a product, even the country's economy as a whole.

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Working Principles

In paving work, in general, the supply of Asbuton into the asphalt layer is carried out with the following steps:

1. It is mixed with aggregate and asphalt using a mechanical asphalt mixing unit, namely the Asphalt Mixing Plant (AMP) to produce hot mixtures or using semi-mechanical tools such as molen concrete or paddle mixer for cold mixes. The next step is to spread it using a mechanical method (finisher), while for cold mixtures it is used manually, then it is compacted using a standard compactor, so that the required density in the specification is obtained.
2. Spread over the aggregate layer on the penetration layer work of & nbsp; macadam & nbsp; with one or two layers. After that, it is compacted using a standard compactor, so that the density is according to specifications.

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Asbuton inside the paved layer will function as follows:

1. Added material that will increase the ability of the paved layer when the traffic load increases. Generally the Asbuton used is a grain type with low bitumen penetration;
2. Substitute hard asphalt. Asbuton which is generally used is the pure type of extraction or grain Asbuton of the LGA type in coating work & nbsp; macadam;
3. Additives and substitutes (substitutes) for some of the hard asphalt used. Asbuton that is commonly used is a grain type with high bitumen penetration, such as LGA or a pre-mixed type.

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Usage

Basically Asbuton can be used on any type of paved coating. It aims to increase rigidity with sufficient flexibility to withstand traffic loads without unexpected damage. Therefore, the use of Asbuton in asphalting work is as follows:

• Hot mix asphalt is used for wear layers, intermediates and foundations.
• Warm mix asphalt is used for wear layers, intermediates and foundations.
• Cold mix asphalt is used to layer between wear and foundation.
• A thin layer of Asbuton sand.
• Thin layer of Asbuton.
• The & nbsp; macadam & nbsp; Asbuton penetration layer.

Based on the results of laboratory scale research and field trial scale, it is found that the asphalt mixture using Asbuton has higher technical properties than the mixture without Asbuton. However, for each type of mixture, the designation should be differentiated according to traffic conditions and environment.

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For hot mixture with Asbuton grain or modified bitumen Asbuton (pre-mixed or semi-extracted Asbuton) or modified bitumen (pure Asbuton or & nbsp; full & nbsp; extraction), preferably for road use with heavy and heavy traffic loads, that is, for traffic plans & gt; 10 million ESA or LHR & gt; 2000 vehicles and the number of trucks more than 15%. Especially for roads that have a maximum field temperature above 60 & ordm; C such as national roads. Meanwhile, for warm mixtures with Asbuton, grains should be used for roads that serve heavy traffic, namely for traffic plans of 1 to 10 million ESA or LHR & lt; 2000 vehicles and the maximum number of trucks 15% such as national and provincial roads.