METHOD FOR THE PRODUCTION OF AN ASPHALT CONSTRUCTION MATERIAL FOR ROAD AND PATH CONSTRUCTION IN A HOT ASPHALT MIXING PLANT

Description

[0001] The invention relates to a process for producing an ultra-low-temperature and cold-laid asphalt construction material. Furthermore, the invention relates to admixtures for carrying out the process.

[0002] Asphalt mix, as defined by EN 13108, is mixed at approximately 180°C, and the installation of the hot mix must be completed before the minimum compaction temperature of approximately 130°C is reached. Disadvantages resulting from the physical properties of state-of-the-art asphalt mix are manifold: The asphalt mix must be dispatched to the construction site very precisely, "just in time," because the asphalt mix must not cool down. The asphalt hardens through the cooling and stiffening of the binder, requiring correspondingly long periods of time after installation, thus leading to traffic congestion due to traffic jams / diversions, or damage due to failure to observe the cooling phase. Adverse weather conditions (cold) prevent or delay the installation of asphalt mix or lead to disposal of material due to premature cooling.

[0003] If the minimum compaction temperature cannot be maintained, for whatever reason, the remaining asphalt must be disposed of, or asphalt mix is ​​paved without observing the temperature window, thereby accepting damage. Long distances cannot be covered for the transport of asphalt mix because the asphalt mix would lose the temperature required for paving.

[0004] Construction using asphalt mix is ​​not flexible for changes in site size and weather conditions.

[0005] It is inherent in this technology that harmful emissions / PAHs are produced due to the hot installation and high energy consumption occurs due to the hot mixing process at 180°C.

[0006] A special form of this asphalt, as defined by EN 13108, is low-temperature asphalt, where the temperature limits are approximately 30°C lower. To reduce the required paving temperature of the asphalt mix, the industry offers additives, usually waxes, to the asphalt mix that reduce the temperature of the asphalt mix and the minimum compaction temperature. While this can reduce many of the emissions, the other physical disadvantages of asphalt technology during paving remain largely unchanged.

[0007] Furthermore, it is known from the state of the art to use cold mix or reactive asphalt for the cold paving of asphalt patches or areas. These binder systems are generally produced cold, for example, at approximately 40°C, and then laid cold, according to cold asphalt or cold mix technology. However, due to their paving properties, such cold mixes are not suitable for the production of large-area asphalt surface courses with a homogeneous degree of compaction.

[0008] US 2008 / 041276 describes a process for producing asphalt mixtures using reclaimed asphalt (recycled asphalt). Substances are added that (a) reduce the aging of the bitumen in the reclaimed asphalt, (b) limit the degree of heating of the asphalt granules, and (c) reduce the degree of oxidation of the bitumen in the reclaimed asphalt. In particular, plasticizer and hardener are added to the reclaimed asphalt during the warm phase—two components that reduce viscosity. Flux oils are used as plasticizers, and FT paraffins as hardeners.

[0009] The present invention aims to modify the asphalt mix produced in asphalt mixing plants using conventional technology by adding a reactive additive, i.e., one or more reactive, temperature-reducing additives, in the mixing plant in such a way that the paving and compaction temperature can be significantly reduced, for example, to a temperature range between 130°C and 20°C. The present invention thus provides, in particular, an asphalt construction material comprising asphalt mix and a reactive additive.

[0010] This should enable cold paving of the asphalt material without the disadvantages of previous asphalt technologies. Furthermore, conventional large-scale asphalt mix production plants should be usable for the production of the asphalt material.

[0011] The invention and the method according to the invention for producing the asphalt building material according to the invention aim to overcome the above-mentioned disadvantages of the standard construction method according to EN 13108 by means of a technically feasible and possible combination of basic asphalt technologies, while at the same time achieving and maintaining the high technical standards.

[0012] The invention combines for the first time the two technological worlds of asphalt mix technology (hot) and modern cold mix technology for hot asphalt plants and can thus overcome the disadvantages of both mix technologies without having to accept any compromises in quality on the technical side.

[0013] The basis is an asphalt construction material with a significantly reduced production temperature according to the invention, particularly in a range between 120°C and 150°C. The state of the art for improving the physical properties during paving of the asphalt construction material involves adding waxes in a special form and composition according to the invention to further reduce the asphalt temperature (e.g., as described in GESTRATA Journal - Das Asphalt Magazin, May 2011, Issue 132). The benefit of adding wax in the application according to the invention goes beyond this mere cooling function and shifting the minimum compaction temperature of the asphalt mix.

[0014] Finally, the principle of wax addition is fundamentally expanded through the application of reactive asphalt technology. According to the invention, this achieves mix qualities that can be applied cold, not just at a lower temperature. Instead of cooling the bitumen binder, controlled hardening—in the sense of stiffening the binder—is achieved through a reaction process in the binder.

[0015] The asphalt building material produced according to the invention can either be installed warm immediately after production, or stored for a limited period at ambient temperature, or filled into suitable containers for storage and transport on small construction sites.

[0016] The method according to the invention or the asphalt building material according to the invention can be used not only for the actual road and path construction but also for the production of ancillary facilities or other asphalt surfaces as well as for the rehabilitation of existing asphalt surfaces of various types.

[0017] The invention further relates to the use of a reactive additive according to the invention. This reactive additive can have all the features described in connection with the process.

[0018] Furthermore, the invention relates to an asphalt construction material as such, comprising an asphalt mixture made of minerals and bitumen. The asphalt construction material further contains a reactive additive containing a bitumen-dissolving flux component and a solid wax component. The reactive additive in this asphalt construction material can have all the features described in connection with the process and / or use.

[0019] The asphalt mix contained in the asphalt building material can have a temperature between 120°C and 150°C. Production example for the asphalt building material according to the invention and its installation:

[0020] The asphalt building material underlying the invention is manufactured in a standard asphalt mixing plant suitable for the production of asphalt mixtures. The mineral mixture is dried, for example, at approximately 130°C and then coated with standard bitumen, e.g., B70 / 100. not It can be further heated to approximately 180°C, as is the state of the art for asphalt mixes. However, it should be noted that in other applications, such as when using a very moist mineral mixture, a higher temperature may be appropriate, particularly up to approximately 150°C.

[0021] It should also be noted that in certain embodiments, recycled asphalt can also be used instead of the mineral mixture or as part of the mineral mixture. The mineral mixture or the corresponding part of the mineral mixture is then a mineral / bitumen mixture.

[0022] Furthermore, the reactive additive, consisting of a bitumen-dissolving flux component A and a wax-solid component B, wherein the solid wax component contains as filler component a filler such as stone flour, talc, cement, lime flour, gypsum, fly ash cement or slag flour from iron or steel production and as wax component a synthetic or natural wax as further described below, is added and the asphalt building material according to the invention is mixed.

[0023] These additives further reduce the mixing temperature to a temperature range of < 100°C during the mixing process. Depending on the specific application, the components of the reactive additive can be added at ambient temperature without the addition of heat energy, and therefore do not need to be heated to a certain temperature beforehand.

[0024] This asphalt building material produced in this way hardens not by lowering the temperature. It can therefore either be processed immediately or stored (intermediately).

[0025] Installation follows the same technical principles as with asphalt mixes. However, curing does not occur through the cooling process, but rather through reactive curing, which is achieved with an activator. During the laying of the asphalt material according to the invention, the activator is added or mixed in, which can initiate the reaction process. Compaction provides the energy required to minimize the technical void content of the asphalt material, thereby generating the necessary shear forces for the homogeneous initiation of the curing reaction in the asphalt material, and must be completed before final curing. The end product produced in this way meets the same standard requirements as asphalt layers produced from asphalt mixes using state-of-the-art technology.

[0026] The minimum processing temperature of the asphalt construction material according to the invention is between 0°C and +30°C, depending on the design of the mix formulation. This makes it possible to process this asphalt construction material in spring / autumn to moderate winter, and even a few days after production. This also allows for better response to influences such as sudden weather changes or construction site size, ultimately producing less waste asphalt and simultaneously improving the quality of the asphalt layers.

[0027] The asphalt building material produced in this way now offers the special advantages mentioned above and overcomes the known disadvantages of asphalt mixtures according to the state of the art: Due to the significantly lower production and installation temperatures, environmentally relevant aspects can be improved through energy savings. The use of recycled asphalt increases the environmental friendliness of the products and meets sustainable procurement criteria. This asphalt construction material reduces the maximum workplace concentration due to emissions such as aerosols and PAHs (polycyclic aromatic hydrocarbons) to an absolute minimum; no emissions are generated during installation at ambient temperature. Furthermore, less waste asphalt is generated, which is generated in the asphalt mix due to excess quantities on the construction site or due to excessive cooling – which makes it unworkable.Earlier reopening of the roadway when using this asphalt material reduces traffic disruptions and congestion, as curing generally begins immediately after the activator is added and is generally completed within a few hours, making the asphalt surface passable. At high ambient temperatures, the controlled reaction process positively influences the reopening of the roadway due to faster curing. At cool ambient temperatures, the low temperatures lead to an increase in the viscosity of the asphalt material according to the invention, thereby resulting in the asphalt material initially becoming stable. Under these conditions, the reaction process is also delayed, advantageously providing a larger time window for compaction activities. The advantages in work planning lie in the easier scheduling of the mix.It can be processed for longer, has a limited storage capacity, and thus covers a larger transport radius (> 80 km) to the construction site. Overtime is also saved in production, as the mix doesn't always have to be produced "just in time." Factors that hinder installation, such as weather, distance to the construction site, and last-minute changes in site size, are less likely to have a negative impact.

[0028] Furthermore, the asphalt building material according to the invention offers, among other things, the following advantages over cold mixes according to the state of the art: The asphalt construction material according to the invention is suitable for the production of large-area asphalt surface courses with a homogeneous degree of compaction. A high final strength is achieved quickly compared to standard cold mixes.

[0029] In the system and method according to the invention, the asphalt construction material is produced at high temperatures in a single operation (between 120°C and 150°C, especially at approximately 130°C). However, the use of the active principle of the state-of-the-art reactive binder system alone could not lead to successful application in asphalt mix technology. The binder and asphalt mix would harden even before the cooling process.

[0030] The reactive additive used according to the invention comprises, in addition to the flux component and the solid component, a wax component, the latter being known to reduce the minimum compaction temperature.

[0031] Due to the production of the asphalt building material according to the invention in one operation, a wax contained in the reactive additive, for example a Fischer-Tropsch wax, is used, which is known to reduce the asphalt mixture temperature (as in the production of low-temperature asphalt) by approximately 20° - 30°C immediately after addition.

[0032] The active principle of the finished asphalt construction material according to the invention is a curing process based on the technical basis of the reactive and cold-curing binder (as described in AT 406 375), and not, as in the prior art of the asphalt mixture, by increasing the viscosity of the binder by cooling.

[0033] Completely surprising, and not obvious to the person skilled in the art, it has been shown in tests that the simultaneous use of flux component, solid and wax component according to the invention leads to a complete change in the physical properties of the asphalt construction material according to the invention compared to conventional asphalt mix, and the asphalt mix technology can suddenly be applied / installed cold.

[0034] Laboratory tests have shown that the wax, in addition to reducing the temperature of the asphalt mix, also prevents premature reaction (hardening) of the asphalt material during the subsequent cooling process. The wax component acts as a kind of "preservative," protecting the introduced reactive system from reacting and triggering hardening of the material.

[0035] The components of the reactive additive can be added to the asphalt mix together or separately. This allows for different implementations of the invention: Variant 1 • Flux component A = oil mixture

[0036] This is a mixture of plasticizing, non-volatile oils, such as mineral, synthetic, or vegetable oils or fats, or derivatives thereof, each of which is capable of dissolving bitumen. These are also called flux oils. • Solid wax component B = wax / filler / fiber (optional)

[0037] A filler additive such as stone flour, talc, cement, lime flour, gypsum, fly ash cement, or slag powder from iron or steel production is mixed with a synthetic or natural wax and, if necessary, fiber, and then pelletized. The filler-to-wax mixing ratio is preferably approximately 90-50 parts filler to 10-50 parts wax.

[0038] The ratio of flux component A to solid wax component B in the reactive additive according to the invention is approximately 40:60. In variant 1, these two components are added successively to the asphalt mix during the mixing process. Variant 2 • Flux component A = oil mixture

[0039] This is a mixture of plasticizing, non-volatile oils, such as mineral, synthetic, or vegetable oils or fats, or derivatives thereof, each of which is capable of dissolving bitumen. These are also called flux oils. • Solid wax component B = wax / filler / oil / fiber (optional)

[0040] A filler additive such as rock flour, talc, cement, lime flour, gypsum, fly ash cement, or slag powder from iron or steel production is mixed with a synthetic or natural wax, fiber (optional), and oil, and optionally pelletized. The oil is a mixture of plasticizing non-volatile oils, e.g., mineral, synthetic, or vegetable oils or fats, or a derivative thereof, each capable of dissolving bitumen; these are also called flux oils.

[0041] The ratio of flux component A to solid wax component B can be adjusted accordingly by adding oil to the solid wax component B. The presence of oil in the solid wax component B results in less wax being contained in this component. This variant is suitable, for example, for handcrafted goods.

[0042] In variant 2, the two components are added successively to the asphalt mix during the mixing process. Variant 3 • Component mixture / 1-component additive

[0043] A filler additive such as rock flour, talc, cement, lime flour, gypsum, fly ash cement, or slag powder from iron or steel production is mixed with a synthetic or natural wax, fiber (optional), and oil, and optionally pelletized. The oil is a mixture of plasticizing, non-volatile oils, e.g., mineral, synthetic, or vegetable oils or fats, or a derivative thereof, each of which is capable of dissolving bitumen; these are also called flux oils. The mixing ratio of oil to wax and filler is preferably between 40:60 and 70:30.

[0044] In variant 3, the components of the component mixture are mixed together and then added together to the asphalt mix.

[0045] In general, it should be noted that component A can also be referred to as the flux component, while component B can also be referred to as the solid-wax component. If components A and B are mixed together before being added to the asphalt mix, the resulting component mixture can also be referred to as the flux-solid-wax component.

[0046] The amount of the reactive additive according to the invention added to the final product depends on the type of building material or the bitumen used, with the ratio of standard bitumen to reactive additive being, for example, approximately 40:60.

[0047] The effective binder content in the final product is again very similar to that of the same type of asphalt mix produced according to the state of the art.

[0048] In general, it should be noted that all content information, unless otherwise stated, is based on the weight of the respective components, for example parts by weight or weight ratios. Examples of implementation:

[0049] As an example of loose asphalt building material according to the invention designed for direct installation, which uses B50 / 70 based asphalt mixture according to EN 13108, the following are given (each in weight percent): Mixing recipe AC 8:

[0050] mineral 92,0% B50 / 70 4,0% Reactive additive according to variant 1 4.0% sum 100,0% Bitumen + reactive additive = 8%, corresponds to 6.3% effective binder Mixing recipe AC 16:

[0051] mineral 92,5% B50 / 70 3,3% Reactive additive according to variant 1 4.2% sum 100,0% Bitumen + reactive additive = 7.5%, corresponds to 5.9% effective binder

[0052] The reactive additive according to this embodiment is a two-component reactive additive consisting of a flux component A and a solid wax component B, wherein the flux component A contains approximately 20 wt.% tall oil, approximately 20 wt.% rapeseed oil, and approximately 60 wt.% mineral oil, and wherein the solid wax component B is a mixture of approximately 80 wt.% beeswax and approximately 20 wt.% cement. The components are mixed separately with the asphalt mixture in a ratio of approximately 60 wt.% A and approximately 40 wt.% B to obtain the asphalt construction material according to the invention.

[0053] The design of the mixing recipe can be adjusted to the desired paving method, the grain composition, the proportion of recycled asphalt and the existing base binder (preferably B 25 - B 300).

[0054] Differences between state-of-the-art asphalt mix and the asphalt building material according to the invention summarized: Asphalt mix inventive asphalt building material Mixing temperature approx. 180°C approx. 130°C Installation temperature min. 130°C 0°C Opening to traffic after densification approx. 2 - 5 hours 0.5 - 2 hours Transport radius < 80km conditionally unlimited Low energy costs no Yes Longer processability no Yes Storage capacity no Yes Emissions during installation (PAH value) problematic not problematic Activator required during installation no Yes* * may not need to be added separately, for example when processing the asphalt building material for small repair work in particularly high humidity and / or rain

Claims

1. A method for producing an asphalt construction material for road and path construction, wherein an asphalt mixture is produced in a hot asphalt mix plant from mineral aggregates and bitumen and optionally a temperature-lowering additive, characterised - in that a bitumen-dissolving flux component and a solid wax component are added to the asphalt mixture as a reactive additive in a mix plant, the solid wax component contains a filler in the form of rock flour, talcum, cement, lime flour, gypsum, fly ash cement or slag flour from iron or steel production as a filler portion and a synthetic or natural wax as a wax portion, and - in that, optionally, an activator is added during or shortly before the installation of the asphalt construction material.

2. The method according to claim 1, characterised in that the asphalt mixture has a temperature prior to the addition of the reactive additive that is at least equivalent to the melting point of the wax contained in the solid wax component, wherein the temperature is preferably between 120 °C and 150 °C.

3. The method according to claim 1 or 2, characterised - in that the flux component is an oil or oil mixture from the group of plasticising oils or fats, mineral oils, synthetic and vegetable oils and derivatives produced therefrom, which are suitable for dissolving bitumen.

4. The method according to claim 1, characterised - in that the filler portion and the wax portion are mixed in a ratio of 90 to 50 parts by weight of the filler portion and 10 to 50 parts by weight of the wax portion and added to the asphalt mixture in the hot mix plant together with the flux component.

5. The method according to one of claims 1 to 4, characterised - in that the solid wax component additionally contains an oil or oil mixture from the group of plasticising oils or fats, mineral oils, synthetic and vegetable oils and derivatives produced therefrom which are suitable for dissolving bitumen, wherein the oil or oil mixture is in particular at least a part of the flux component, and / or - in that the solid wax component also contains fibre.

6. The method according to one of claims 1 to 5, characterised - in that the optionally added activator is selected from the group of water, glycols, fatty alcohols, surfactants (anionic, nonanionic or catonic) or solutions thereof in water or other solvents, organic and inorganic acids and alkalis, metal salts, sulphur and its compounds, peroxides, latex or synthetic resin dispersions.

7. The method according to one of claims 1 to 6, characterised - in that the ratio of flux component to solid wax component is between 40:60 and 70:30.

8. The method according to one of claims 1 to 7, characterised - in that the ratio of bitumen to reactive additive is between 30:70 and 70:30.

9. The method according to one of claims 1 to 8, characterised - in that the asphalt construction material ready for installation has a mineral content of 85 to 95 % by weight, a bitumen content of 2.0 to 14 % by weight and a reactive additive content of 1 to 13 % by weight, and / or - in that the asphalt construction material includes the binder, mineral and additive proportions permitted in EN 13108 and / or in the requirements and specifications for cold mixes.

10. The method according to one of claims 1 to 9, characterised in that the mineral aggregates consist of or comprise recycled asphalt.

11. The method according to one of claims 1 to 10, characterised - in that the flux component and the solid wax component are mixed separately into the asphalt mixture, or - in that the flux component and the solid wax component are mixed with each other and then added to the asphalt mixture as a flux-solid wax component.

12. A use of a reactive additive in the production of an asphalt construction material based on an asphalt mixture of mineral aggregates and bitumen, characterised in that the reactive additive contains a bitumen-dissolving flux component and a solid wax component, wherein the solid wax component contains a filler such as rock flour, talcum, cement, lime flour, gypsum, fly ash cement or slag flour from iron or steel production as a filler portion and a synthetic or natural wax as a wax portion.

13. The use according to claim 12, characterised in that prior to the addition of the reactive additive the asphalt mixture has a temperature which is at least equivalent to the melting point of the wax contained in the solid wax component, wherein the temperature is preferably between 120 °C and 150 °C.

14. An asphalt construction material containing an asphalt mixture of mineral aggregates and bitumen, characterised in that the asphalt construction material contains a reactive additive which contains a bitumen-dissolving flux component and a solid wax component, wherein the solid wax component contains a filler such as rock flour, talcum, cement, lime flour, gypsum, fly ash cement or slag flour from iron or steel production as a filler portion and a synthetic or natural wax as a wax portion.

15. The asphalt construction material according to claim 14, characterised in that it has an installation temperature between 0 °C and 130 °C.