Method for preparing modified asphalt by adopting raw material with low asphaltene content

Abstract

The invention relates to a method for preparing modified asphalt by adopting a raw material with low asphaltene content. The method provided by the invention comprises the following steps of: carrying out thermal cracking reaction with reduced pressure residual oil, deoiled asphalt or mixture with the asphaltene content to be less than 5% at the temperature of 350-450 DEG C, then distilling and cutting to obtain tower bottom residue high-asphaltene-content component with the atmospheric boiling point of being higher than 350 DEG C; mixing the high-asphaltene-content component with a compatilizer at the temperature of 140-190 DEG C, adding a polymer modifier, shearing for 5-120 minutes at the temperature of 160-200 DEG C by adopting a high-speed shearing machine or a colloid mill, so as to disperse polymer into asphalt physically; and warming to a reaction temperature of 160-230 DEG C, adding stabilizer composition, stirring and reacting for 30-360 minutes, and carrying out chemical reaction on the polymer and the asphalt, so that the modified asphalt is obtained. The polymer modified asphalt obtained by the method provided by the invention has the advantages of high temperature storage stability, excellent high-and-low temperature performances and high ageing resistance, a technological process is simple, and production efficiency is high.

Description

technical field [0001] The invention relates to a method for preparing modified asphalt from raw materials with low asphaltene content, in particular to a method for preparing styrene-butadiene-styrene (SBS) modified asphalt. Background technique [0002] Compared with cement concrete pavement, asphalt pavement has the advantages of smooth surface, no joints, comfortable driving, wear resistance, small vibration, low noise, short construction period, and easy maintenance and repair, so it has been more and more widely used. With the rapid development of the economy, the road mileage in my country will increase year by year. Taking Xinjiang as an example, the road mileage will double during the "Twelfth Five-Year Plan" period in the future. The quality requirements of road surfaces are also getting higher and higher. Ordinary asphalt is a material with strong temperature sensitivity. When the temperature drops to near the brittle point, the asphalt becomes glassy and loses fl...

AI Technical Summary

Problems solved by technology

One of the commonly used preparation techniques at present is the mother liquor method, which is to mix SBS with rich aromatic hydrocarbon solvent to make a high-concentration SBS modified asphalt masterbatch, and then mix the masterbatch with matrix asphalt to prepare modified asphalt, such as CN1339557, CN1138869, CN1415663, CN1228456, CN1733832, CN1775910, USP4567222 all provide the preparation method of masterbatch method to prepare modified asphalt, to achieve the purpose of improving stability, but when preparing SBS modified asphalt masterbatch, because of SBS swelling causes material viscosity to rise sharply , resulting in difficulty in stirring, and due to the long swelling time of SBS, it is easy to cause aging and agglomeration of SBS. In addition, when preparing modified asphalt masterbatch, it needs to be cooled, and it needs to be heated during mixing with asphalt. At the same time, it must be added A certain amount of stabilizer is used for long-term cross-linking reaction to achieve the purpose of preparing modified asphalt with stable storage. Therefore, this process has the defects of long production cycle, high production cost and high energy consumption.

The second is the high-speed shearing or colloid mill process, which directly disperses SBS into the asphalt after being ground by a high-speed shearing machine or colloid mill. This process has the advantages of short production cycle and high production efficiency, and can realize continuous production. However, the modified asphalt produced by this process is easy to segregate, has poor storage stability, and the physical and chemical indicators of the product are unstable.

The problem with this process is that it is necessary to use a special styrene-diene polymer that has been chemically modified in the factory. Once it is replaced with a non-modified styrene-diene polymer, the performance and storage stability of the product will be affected. cannot be guaranteed, making its application not universal

The second is composite modification, which is to prepare a polymer asphalt composition with good stability by using polymers with different compositions or structures for compounding, and using the complementary effects of their properties. Polymers with different compositions or structures have different effects on asphalt modification The performance after hardening has different effects. CN1417262 is modified by compounding elastomeric polymers and polyethylene waxes or glycidyl ester compounds. The softening point difference of the prepared modified asphalt segregation test is ≤ 2.5 ° C. During the storage process The separation of polymer and asphalt will not occur, but some indicators of modified asphalt are not ideal, showing poor low temperature performance

[0011] Among these four types of stabilizers, sulfur and its compounds are mostly used. It has the advantages of cheap and easy-to-obtain raw materials, fast cross-linking speed, and wide application range. However, the amount and speed of sulfur added have a great impact on the reaction results. Adding sulfur too fast or too much at one time will cause excessive cross-linking of the asphalt-polymer and coagulate into a colloid, resulting in difficulty in flow and unable to continue production

In order to avoid excessive cross-linking, sulfur is used as a cross-linking agent in WO984537, and multiple slow additions are adopted, resulting in cumbersome process steps and long processing time, therefore, the processing capacity is limited

CN101068883A produces a kind of polymer-modified asphalt with improved high-temperature properties by adding sulfur and / or other cross-linking agents or accelerators to produce a kind of polymer-modified asphalt by earlier using inorganic acid to asphalt pretreatment, but the storage stability of modified asphalt is not very it is good

However, for asphalt with low aromatic content and low asphaltene content, on the one hand, the compatibility between asphalt and polymer is poor, and on the other hand, the asphalt contains less active components, resulting in poor compatibility with polymer and modified asphalt. The storage stability of the asphalt is very poor. To solve the problem of polymer modification of this kind of asphalt, it is necessary to comprehensively consider the effects of various influencing factors. First of all, it is necessary to adopt a new process to make the components of the base asphalt change appropriately. Make a reasonable ratio between the four components, and then select a suitable stabilizer, and finally obtain a polymer-modified asphalt with excellent performance

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