CH622025A5 - Process for the preparation of a bituminous mixture, and the use thereof for surface coatings - Google Patents

Description

The present invention relates to a method for producing a bituminous mixture from a chemically modified bituminous binder, a mineral aggregate and / or a filler. The invention also relates to the use of such a bituminous mixture for surface coatings.

It is known per se to coat surfaces with mixtures of bituminous binders and a mineral aggregate and / or fillers. Such mixtures can be applied directly to a surface as such, and this is also referred to as ready-to-install mixtures, or they can be prepared on the surface itself, and such mixtures are then said to be suitable for the soil mixing process. Such measures are particularly useful for road construction, such as for the production of road coverings, for hydraulic engineering, for erosion control and for the construction industry, for example for the manufacture of roof and floor coverings, as well as for sealing pipes. Both ready-to-install mixtures and mixtures suitable for the soil mixing process are usually produced by mixing the components in question at elevated temperatures in the range from, for example, 100 to 250 ° C., although lower working temperatures can also be used, for example ambient temperature. If ready-to-install mixtures for hot installation are to be produced, the components in question are generally preheated to a temperature in the predetermined range before they are intimately mixed with one another. As far as mixtures for the soil mixing process are concerned, usually only the bituminous binder is preheated to a temperature in the aforementioned range and then mixed with the mineral aggregate and / or filler on the surface in question. Such measures using premixes or ready-to-install mixtures are discussed in the relevant literature, for example in “Asfalt”, published by the Vereniging voor Bitumineuze Werke (1973).

Various bituminous binders have already been combined with mineral aggregates and / or fillers in order to produce ready-to-install mixtures or mixtures for the soil mixing process. In practice, however, the selection of the binder component is generally limited to those binders which have a sufficiently low viscosity at the mixing temperature. For the production of ready-to-install mixtures, such a low viscosity is required both for spraying or pumping the binding agent in question into the mixing zone or mixing chamber of the mixing device in question, and for good, intimate mixing in the mixing device with the mineral aggregate or filler.

In the case of mixtures for the soil mixing process, a low viscosity is necessary so that the binder can be pumped or sprayed onto the surface. In general, binders are considered unsuitable or unmanageable if the viscosity at the mixing temperature in question exceeds 400 to 500 centistokes (cSt). Chemically modified bituminous binders are also very suitable per se for the above-mentioned purpose, but such modified binders have not yet been used on an industrial scale because of their very high viscosities.

Surprisingly, it has now been found that it is also possible to produce bituminous mixtures using such highly viscous binders, provided that only care is taken to ensure that at least part of the binder in question is chemically modified only in situ in the presence of the aggregate and / or filler.

The process according to the invention for producing a bituminous mixture of a chemically modified bituminous binder, a mineral aggregate and / or a filler is accordingly characterized in that the chemical modifier is mixed with at least part of the non-emulsified binder only while it is being mixed with the aggregate and / or filler to implement.

The process according to the invention is particularly suitable for producing ready-to-use mixtures, in particular ready-to-use mixtures for hot installation, i.e. of mixtures which are produced at elevated temperatures, for example in the temperature range from 100 to 250 ° C. If mixtures are to be produced for installation at ambient temperature, the bituminous binders in question can be used in the form of a bitumen, i.e. of a bitumen that has been diluted with a volatile solvent. Such waste bitumen, however, is only used to a small extent, in particular in road construction, because its setting time is very long and, moreover, the mixture remaining after the solvent has evaporated off does not

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has good physical properties. Such bituminous binders consisting of a waste bitumen also do not always present difficulties in handling, even if they have been produced from a chemically modified bitumen. When using the method according to the invention, however, it is possible to use less solvent than usual in such waste bitumen if the chemical modification is carried out in situ.

Although any chemically modified bituminous binders and any mineral aggregates and / or fillers can be used as starting materials for the process according to the invention, it is particularly well suited for the production of mixtures of chemically modified blown bituminous binders. In particular, chemically modified fully blown bituminous binders can be used for this purpose, as can chemically modified bituminous binders that have already been modified with malic acid and any mineral aggregates and / or fillers.

Blown bitumens are known per se and are either partially blown or fully blown bitumens. Partially blown bitumens are produced by blowing a starting bitumen material, such as gilsonite or a directly distilled bitumen (distillate bitumen), with air or oxygen at elevated temperatures until a certain penetration value is reached. Fully blown bitumen types, on the other hand, have a higher viscose elasticity and are often produced by making a blended bitumen from a partially blown bitumen by dilution with a volatile solvent and then blowing this blended bitumen from a partially blown starting material again with air or oxygen at elevated temperatures.

Blown bitumens of this type can be reacted by means of chemical modifiers, for example with inorganic acids or organic acids or their anhydrides. For this, e.g. Hydrochloric acid, phosphoric acid, maleic acid or maleic anhydride, furthermore alkali hydroxides, such as sodium hydroxide, potassium hydroxide or lithium hydroxide. Other suitable modifiers are organic or inorganic halides, such as aluminum, titanium or boron halides. Inorganic acids, such as phosphoric acid, and alkali hydroxides, such as potassium hydroxide, are preferred according to the invention as chemical modifiers. The chemical modifier can be used in a concentration in the range of 0.1 to 10 percent by weight based on the amount of the bituminous binder. Before the blown bitumen is subjected to such a chemical modification treatment, it can also be mixed with extenders and / or with polymeric substances.

Bituminous binders which have been prepared by reacting a starting bitumen, such as gilsonite, directly distilled bitumen, propane bitumen or blown bitumen either as such or in a mixture with extenders and / or polymeric substances, using, for example, 0.5 to 10 percent by weight of one olefinically unsaturated acid anhydride, such as maleic anhydride, or an olefinically unsaturated acid, such as Maleic acid,

are known per se. This type of bituminous binder is hereinafter referred to as maleic acid-modified bituminous binder for the sake of simplicity. The production of such maleic acid-modified bituminous binders from bitumen-polymer mixtures has already been proposed (cf. DE OS 2 513 514, published October 2, 1975). Polymeric substances suitable for this purpose are olefinically unsaturated elastomers with molecular weights in the range from 100,000 to 500,000, such as styrene-butadiene copolymer.

polymers. Such copolymers are commercially available, for example under the names "Cariflex" S 1712 and "Cariflex" S 1500. The polymeric substances can be suitably used in amounts below 10 percent by weight, based on the bituminous binder, with polymer concentrations in the range of 0 , 1 to 7.0 percent by weight are preferred.

Such maleic acid-modified bituminous binders, which suitably have acid values in the range from about 0.01 to 2.0 milliequivalents / gram, determined by titration, can be used very well as starting materials to be modified in the process according to the invention.

Such maleic acid-modified bituminous binders can be further modified according to the invention by means of ionic or covalent coupling using a suitable chemical modifier. Suitable chemical modifiers for coupling with maleic acid-modified bituminous binders have already been proposed in the aforementioned OS2513514. It has also been proposed to carry out the coupling reaction of emulsified maleic acid-modified bituminous binders in the presence of a mineral aggregate and possibly other coupling agents in this earlier right.

Chemical modifiers suitable for the ionic coupling of maleic acid-modified bituminous starting binders are compounds of the metals of groups I to IV and in particular of subgroups IA to IVA of the Periodic Table of the Elements, such as compounds of lithium, sodium, potassium, calcium, magnesium, barium, aluminum and Lead. The hydroxides, alkoxides and salts of weak acids of these metals are very suitable for this purpose. Lithium hydroxide, sodium hydroxide, potassium hydroxide and barium hydroxide as well as lead (II) acetate, magnesium acetate, aluminum isopropoxide and / or aluminum sec-butoxide are very particularly suitable. The chemical modifier is preferably used as an aqueous solution or in liquid form at the mixing temperature.

Chemical modifiers which are capable of forming esters, thioesters, amide groups or imide groups are suitable for the covalent coupling of a maleic acid-modified bituminous binder as a starting material. Such groups form when organic compounds with at least two functional groups are used which can react with the groups bound to the maleic acid-modified bituminous binder. Suitable functional groups in such chemical modifiers are the hydroxyl group, the mer-capto group, the amino group and the N-hydrocarbyl-amino group as well as the epoxy group, e.g. an epoxyalkyl group, and isocyanate groups. Examples of suitable chemical modifiers are ethylene glycol, diethylene glycol, 1,4-butanediol, glycerol, trimethylolpropane, the di-glycidyl ester of bisphenol A, methylene diphenyl-4,4'-diisocyanate, tolylene di-isocyanate, triethylenetriamine, tetraethylene -pentamine and diethanolamine.

For the coupling of maleic acid-modified bituminous binders used as starting material, the modifiers are used in amounts of 28 to 500 percent by weight of the amount which is required to react stoichiometrically with the binder in question, i.e. to neutralize this. The chemical modifier is preferably used in concentrations of 50 to 300 percent by weight and in particular 75 to 200 percent by weight, based on the amount theoretically required. That as the starting material

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Maleic acid-modified bituminous binders used can also be mixed with extenders and / or polymeric substances before chemical modification.

The method according to the invention is particularly suitable for producing mixtures of chemically modified blown bituminous binders or again chemically modified already maleic acid-modified bituminous binders with mineral aggregates and / or fillers. This is due to the fact that blown bituminous binders and maleic acid-modified blown bituminous binders, in particular if less than 10% by weight of maleic anhydride have been used for their production, have viscosities below the stated limit of 400 to 500 cSt at the usual mixing temperatures and therefore on are easy to handle, but the chemically modified blown bituminous binders and the again chemically modified, already maleic acid-modified bituminous binders have viscosities of well over 400 to 500 cSt and usually even over 1000 cSt at the usual mixing temperatures and are therefore practically unmanageable and difficult to mix are.

However, the process according to the invention is not restricted to mixtures which have been obtained by means of chemically modified bituminous binders of the type mentioned above. For example, the method according to the invention can also be used to produce a bituminous binder modified with maleic acid and having a high acid content. As already stated above, maleic acid-modified bituminous binders produced using less than 10% by weight of maleic anhydride usually have viscosities below 500 cSt at the mixing temperature, but for the production of maleic anhydride amounts of e.g. above 20 percent by weight, the binder obtained can have such a high viscosity that it can no longer be handled. The method according to the invention can therefore be used to chemically modify a starting bitumen, for example a distillate bitumen, using maleic acid or maleic anhydride, or a bituminous starting binder which has already been modified with maleic acid can be further modified with maleic acid or with maleic anhydride.

A conventional mineral aggregate or a conventional filler can be used for the process according to the invention. Suitable mineral aggregates are, for example, gravel, bauxite, granite, sandstone, basalt, porphyry, dolomite, slag and limestone. Suitable fillers consist for example of limestone, sand, asbestos and / or glass fiber. In general, the mineral aggregates are particles that do not pass through a 75 micron mesh screen, while fillers generally have a particle size such that they pass through a 75 micron mesh screen. In general, the proportion of mineral aggregate in the mixtures which can be produced according to the invention is 10 to 5000 percent by weight, based on the homogeneous bituminous binder.

For the preparation of ready-to-install mixtures, the three starting components, i.e. the bituminous binder, the mineral aggregate and / or the filler and the chemical modifier are fed separately into the mixing zone. However, it is also possible to first mix the mineral aggregate and / or the filler with the chemical modifier or the bituminous binder. It is advantageous to feed the chemical modifier into the mixing zone only after the bituminous binder and the mineral aggregate and / or the filler have been premixed with one another for a certain time.

The invention is illustrated by the examples below. In these examples, the stated viscosities were determined in accordance with ASTM D-2170 using a capillary viscometer. The penetration values were measured using ASTM regulation D-5 (25 ° C., 0.1 mm), and the softening points were determined in ° C. using the ring and ball method. The Marshall test was carried out in accordance with ASTM D-1559 after compression at 160 ° C.

example 1

Production of a maleic acid-modified bituminous binder.

1000 g of a fully blown Kuwait bitumen (penetration 40, softening point 85 ° C) are mixed with 200 g of an aromatic oil extract (Dutrex 729 HP) and thereby stretched. This mixture is then heated to 175 ° C. and then 24 g (2 percent by weight) of maleic anhydride are added and this mixture is kept at a temperature of 170 to 180 ° C. for a further 2 hours with occasional stirring. The homogeneous product thus produced has a viscosity of 175 cSt and an acid value of 0.23 milliequivalents / g at 190 ° C.

Example 2 (comparison test)

1200 g of the maleic acid-modified bituminous binder prepared according to Example 1 are heated to 160 to 180 ° C. Then 15 g of potassium hydroxide are added with stirring. The temperature is maintained in the range of 160 to 180 ° C for half an hour to two hours. The viscosity of the chemically modified product thus obtained is so high that it cannot be determined, and it is not possible to process this product in a conventional hot mixing device.

Example 3

66 g of the maleic acid-modified bituminous binder prepared according to Example 1 are pumped into the mixing zone of a laboratory hot mixing device at a temperature of 175 to 180 ° C., and at the same time 1200 g of a conventional road construction mineral aggregate, 55% by weight of stones, are added separately with a particle size of 0.2 to 1.8 cm, 35 percent of sand with a particle size of 2 mm and 10 percent of filler with a particle size smaller than 64. Then 1.0 g of potassium hydroxide is added to the mixture as an aqueous solution, and the mixing is continued for one minute. In this ready-to-install mixture, a chemically modified bituminous binder is intimately connected to the mineral aggregate and shows excellent processing properties including good compactibility. The data obtained from the Marshall test are summarized in Table I below.

Example 4

Production of a maleic acid-modified bituminous binder.

The procedure of Example 1 is repeated using a half-blown Kuwait bitumen (penetration 80 to 100, the data of the Marshall test are summarized in Table I). 48 g of maleic anhydride (4 percent by weight) are also used. The homogeneous product obtained has a viscosity of 190 ° C

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about 109 cSt and an acid value of about 0.40 milliequivalents / g.

Example 5

The procedure of Example 2 is repeated using 1200 g of the maleic acid-modified bituminous binder prepared according to Example 4 and with the addition of 34 g of the diglycidyl ether of bisphenol A. The product thus obtained has a viscosity of 1800 cSt at 190 ° C. and it is not possible to process this binder in a conventional hot mixer.

Example 6

The procedure of Example 3 is repeated using 66 g of the maleic acid-modified bituminous binder prepared according to Example 4 and 1.9 g of the diglycidyl ether of bisphenol A. In this case, however, the hot-installable mixture of chemically modified bituminous binder shows u. Mineral aggregate excellent properties and good compactibility. The corresponding values of the Marshall test are listed in Table I. Corresponding results are achieved if potassium hydroxide is used instead of the diglycidyl ether of bisphenol A as a chemical modifier.

Example 7

Production of a maleic acid-modified bituminous binder.

The procedure of Example 1 is repeated using a bitumen with a penetration of 80 to 100, which was prepared by blending 565 g of an Iran propane bitumen with 635 g of an Iran short residue, with 4 percent by weight of a styrene -Butadiene rubber can be added (commercial product «Cariflex» S-1500). 24 g (2 percent by weight) of maleic anhydride are reacted with the starting bitumen. The homogeneous end product obtained in this way has a viscosity of 200 cSt and an acid value of 0.17 milliequivalents / g at 190 ° C.

Examples 8 and 9 (comparative tests)

The procedure of Example 2 is repeated using 1200 g of the maleic acid-modified bituminous binder prepared according to Example 7 and of 26.9 g KOH (Example 8) or 39.3 g aluminum sec-butoxide (Example 9). The products obtained have such a high viscosity that this cannot be determined, and the bituminous binders in question cannot be processed in a conventional hot-mixing apparatus.

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Examples 10 and 11 The procedure of Example 3 is carried out using 66 g of the bituminous binder modified according to Example 7 and 1.5 g of KOH (Example 10) or 2.2 g of aluminum sec-butoxide (Example 11) ) repeated. The ready-to-install mixtures thus obtained, which contain the chemically modified bituminous binder and a mineral aggregate, have excellent properties and are easy to compact. The experimental data obtained from the Marshall test are shown in Table I below.

Example 12 (Comparative Experiment) The procedure of Example 2 is repeated using 1200 g of a homogeneous, fully blown Kuwait bitumen (penetration 40, softening point 88 ° C., viscosity at 190 ° C.: 300 cSt) and 12 g KOH. The product thus obtained has a very high viscosity and cannot be processed in a conventional hot mixing device.

Example 13

The procedure of Example 3 is repeated using 66 g of the fully blown Kuwait bitumen described in Example 12 and 0.7 g of KOH. The ready-to-install mixture of a chemically modified bituminous binder and mineral aggregate thus obtained has excellent properties and good compressibility. The data obtained from the Marshall test are summarized in Table I below. Corresponding favorable results are achieved if phosphoric acid is used as the chemical modifier instead of KOH.

TABLE I

example

1 * PM (kN)

2 * Fm (mm)

Q. \ i (PM / FM)

Kuwait 80/100 3 *

6.7

4.8

1.4

3rd

11.3

2.1

6.3

6.

14.2

4.1

3.5

10th

11.5

3.9

3.0

11.

12.2

3.3

3.7

13.

15.6

3.1

5.0

1 * stability 2 * flow value 3 * cf. Example 4

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Claims (10)

622025 2nd PATENT CLAIMS 1. A process for producing a bituminous mixture of a chemically modified bituminous binder, a mineral aggregate and / or a filler, characterized in that the chemical modifier is mixed with at least part of the non-emulsified binder only while it is being mixed with the aggregate and / or Filler brings to implementation. 2. The method according to claim 1, characterized in that the binder in the modified state at the mixing temperature has a viscosity of more than 400 to 500 cSt. 3. The method according to claim 1, characterized in that a blown bitumen is modified. 4. The method according to claim 3, characterized in that 0.1 to 10 percent by weight of the modifier, based on the non-emulsified binder, are used. 5. The method according to claim 3 or 4, characterized in that an inorganic acid or an alkali metal hydroxide are used as modifiers. 6. The method according to claim 1, characterized in that a non-emulsified binder obtained by reacting a mixture of bitumen and a polymer with maleic anhydride is used as the starting material. 7. The method according to claim 6, characterized in that the modifier is used in a concentration of 75 to 200 percent of the amount required for the reaction with the non-emulsified binder. 8. The method according to claim 7, characterized in that a hydroxide or alkoxide of a metal from groups I to IV of the periodic table of the elements is used as modifier. 9. The method according to claim 7, characterized in that an organic compound having at least two functional groups which are suitable for reaction with groups of the non-emulsified binder is used as the modifier. 10. Use of the bituminous mixture produced by the process according to claim 1 for surface coatings.