ASPHALT COMPOSITION COMPRISING A MIXTURE OF AN ISOCYANATE AND A PLASTICIZER AS PERFORMANCEADDITIVES

Abstract

An asphalt composition comprising 0.1 to 8 wt.-% based on the total weight of the composition of an Isocyanate as thermosetting reactive compound and 0.1 to 8 wt.-% based on the total weight of the composition of a plasticizer selected from the group consisting of orthophthalates, terephthalates, cyclohexanoates, azelates, actetates, butyrates, valeriates, alkylsulfonates, adipates, benzoates, dibenzoates, citrates, maleates, phosphates, sebacates, sulfonamides, epoxy es-ters, trimellitates, glycerol esters, succinates, mineral oils and polymeric plasticizers or mixtures thereof, wherein the polymeric plasticizer is selected from the group consisting of Hexanedioic acid polymer with 2,2-dimethyl-1,3-propanediol and 1,2-propanediol isononyl ester, Hexanedioic acid polymer with 1,2-propanediol octyl ester and Hexanedioic acid polymer with 1,2-propanediol acetate or mixtures thereof.

Claims

1.-16. (canceled)

17. An asphalt composition comprising 0.1 to 8 wt.-% based on the total weight of the composition of an Isocyanate as thermosetting reactive compound and 0.1 to 8 wt.-% based on the total weight of the composition of a plasticizer selected from the group consisting of orthophthalates, terephthalates, cyclohexanoates, azelates, actetates, butyrates, valeriates, alkylsulfonates, adipates, benzoates, dibenzoates, citrates, maleates, phosphates, sebacates, sulfonamides, epoxy esters, trimellitates, glycerol esters, succinates, mineral oils and polymeric plasticizers or mixtures thereof, wherein the polymeric plasticizer is selected from the group consisting of Hexanedioic acid polymer with 2,2-dimethyl-1,3-propanediol and 1,2-propanediol isononyl ester, Hexanedioic acid polymer with 1,2-propanediol octyl ester and Hexanedioic acid polymer with 1,2-propanediol acetate or mixtures thereof.

18. The asphalt composition according to claim 17, wherein the isocyanate has a functionality of at least 2.0.

19. The asphalt composition according to claim 17, wherein the isocyanate is selected from the group consisting of monomeric MDI, polymeric MDI, MDI prepolymers, TDI and HDI.

20. The asphalt composition according to claim 17, wherein the isocyanate is polymeric MDI.

21. The asphalt composition according to claim 20, wherein the polymeric MDI has a viscosity in the range of from 10 to 5000 cps/mpas at 25° C.

22. The asphalt composition according to claim 20, wherein the amount of polymeric MDI is of from 0.5 to 5.0 wt.-% based on the total weight of the composition.

23. The asphalt composition according to claim 17, wherein the plasticizer is selected from the group consisting of orthophthalates, terephthalates, cyclohexanoates, alkylsulfonates, adipates, benzoates, citrates, maleates, mineral oils, and mixtures thereof.

24. The asphalt composition according to claim 17, wherein the plasticizer is selected from the group consisting of Diisononyl phthalate, Diisodecyl phthalate, Bis(2-propylheptyl)phthalate, Bis(2-ethyl hexyl)phthalate, Bis(2-ethylhexyl)terephthalate, Dibutyl phthalate, Diisobutyl phthalate, Benzylbutyl phthalate, Diisobutyl terephthalate, Diisononyl 1,2-cyclohexanedicarboxylic acid and (C10-C21)-Alkylsulfonic acid ester of phenol, and mixtures thereof.

25. The asphalt composition according to claim 17, wherein the plasticizer is selected from the group consisting of Bis(2-ethylhexyl)terephthalate, (C10-C21)-Alkylsulfonic acid ester of phenol and Diisononyl 1,2-cyclohexanedicarboxylic acid, and mixtures thereof.

26. The asphalt composition according to claim 17, wherein the amount of plasticizer is of from 0.5 to 5.0 wt.-% based on the total weight of the composition.

27. The asphalt composition according to claim 17, wherein the ratio of an isocyanate as thermosetting reactive compound to plasticizer is in the range of from 80:1 to 1:80.

28. A process for the preparation of an asphalt composition according to claim 17 comprising the following steps: a) heating up the starting asphalt to a temperature of from 110 to 190° C. b) adding an amount of isocyanate and an amount of plasticizer, concurrently or consecutively, c) after step b) the reaction mixture is stirred for at least 2 h at a temperature in the range of from 110 to 190° C. or homogenized for a duration in the range of from 2 to 180 s, and optionally, d) determined completion of reaction by IR spectroscopy, wherein the reaction is under an oxygen atmosphere.

29. The process according to claim 28, wherein the temperature in step a) and step c) are the same and in the range of from 110 to 165° C.

30. A method comprising utilizing the asphalt composition according to claim 17 for the preparation of an asphalt mix composition.

31. The method according to claim 30, wherein the granular material for the asphalt mix composition comprises of from 5 to 100 weight-% of reclaimed asphalt pavement.

32. The method according to claim 30 for pavement applications.

Description

EXAMPLES AND COMPARATIVE EXAMPLES

[0146] Characterization Methods [0147] a) Asphalt tests

[0148] Softening Point (“ring and ball method”) According to DIN EN 1427

[0149] Two horizontal disks of asphalt, cast in shouldered brass rings, are heated at a controlled rate in a liquid bath while each supports a steel ball. The softening point is reported as the mean of the temperatures at which the two disks soften enough to allow each ball, enveloped in asphalt, to fall a distance of 25±0.4 mm.

[0150] Rolling Thin Film Oven Test (RTFOT or RTFO test) according to DIN EN 12607-1

[0151] Asphalt is heated in cylindrical glass bottles in an oven for 75 min at 163° C. (8 bottles can be employed per run). The bottles are rotated at 15 rpm and heated air is blown into each bottle at its lowest point of travel at 4000 mL/min. The effects of heat and air are determined from changes in physical test values which are measured before and after the oven treatment. The RTFO test simulates aging during manufacturing (mixing), mix transportation and placement/laydown (=short term aging of asphalt binders).

[0152] Pressure Aging Vessel (PAV) According to DIN EN 14769

[0153] A sample which experienced short term aging by the RTFO test is placed inside a standard stainless-steel pan and aged at a specified conditioning temperature (90° C., 100° C. or 110° C.) for 20 h in a vessel pressurized with air to 2.10 MPa. The temperature is selected according to the grade of the asphalt binder (application). Finally, the sample is vacuum degassed. The test simulates aging during in-service life (long-term aging).

[0154] Dynamic Shear Rheometer (DSR) according to DIN EN 14770, ASTM D7175

[0155] A dynamic shear rheometer test system consists of parallel plates, a means for controlling the temperature of the test specimen, a loading device, and a control and data acquisition system. It is used to determine rheological properties of asphalt binders. The complex shear modulus is an indicator of the stiffness or resistance of asphalt binder to deformation under load. The complex shear modulus and the phase angle define the resistance to shear deformation of the asphalt binder in the linear viscoelastic region.

[0156] “Bitumen-Typisierungs-Schnell-Verfahren” (BTSV)—Determination of BTSV Temperature and BTSV Phase Angle

[0157] A 25 mm diameter asphalt binder test specimen is pressed between parallel metal plates at a defined frequency in a DSR device. One of the parallel plates is oscillated with respect to the other at, in this case, 1.59 Hz and angular deflection amplitudes. The temperature is increased with a constant rate of 1.2° C./min. The measurement is started at 20° C. Heating at a constant rate progresses until a complex modulus of 15 kPa is reached. The temperature and phase angle at this point is defined as the BTSV temperature (T.sub.BTSV, [° C.]; may alternatively be used instead of the softening point, since T.sub.BTSV correlates well with the hardness of binders, i.e. hard binders feature high T.sub.BTSV and soft binders feature low T.sub.BTSV) and BTSV phase angle (δ.sub.BTSV, [°]; is a measure for the elasticity of the binder, i.e. binders with low elastic properties like for example paving grade asphalt binders feature a high δ.sub.BTSV, whereas modified binders like for example polymer modified asphalt binders feature a low δ.sub.BTSV). (“Das Bitumen-Typisierungs-Schnell-Verfahren”, Alisov et al., Stralle and Autobahn, August 2018; “Modifzierung bestimmen”, M. Sutor-Fiedler, Asphalt & Bitumen May 2017)

[0158] Determination of Asphalt Binder Viscosity

[0159] A 25 mm diameter asphalt binder test specimen is pressed between parallel metal plates at a defined shear rate in a DSR device. At 150° C., the viscosity is determined at a shear rate of 10 1/s.

[0160] Temperature Sweep According to DIN EN 14770

[0161] This test has the objective of measuring the complex shear modulus and phase angle for asphalt binders with a DSR device. An 8 or 25 mm diameter asphalt binder test specimen is pressed between parallel metal plates at a defined frequency and temperature. One of the parallel plates is oscillated with respect to the other at, in this case, 1.59 Hz and angular deflection amplitudes. The required amplitudes must be selected in a way that the testing is done within the region of linear behavior. This is repeated at 30° C., 40° C., 50° C., 60° C., 70° C., 80° C. and 90° C.

[0162] Multiple Stress Creep Recovery Test (MSCRT or MSRC Test) According to DIN EN 16659, ASTM D7405

[0163] The MSCRT is employed to determine the presence of elastic response in an asphalt binder under shear creep and recover at two stress levels (0.1 and 3.2 kPa) at a specified temperature (60° C.). This is carried out with a DSR device. A 25 mm asphalt binder test specimen is set under a constant stress for 1 s, and then allowed to recover for 9 s. Ten creep and recovery cycles are run at 0.100 kPa creep stress followed by ten cycles at 3.200 kPa creep stress.

[0164] Bending Beam Rheometer (BBR) According to DIN EN 14771, ASTM D6648

[0165] The mid-point deflection of a simply supported prismatic beam of asphalt binder subjected to a constant load applied to its mid-point is determined. A prismatic test specimen is placed in a controlled temperature fluid bath and loaded with a constant test load for 240 s. The test load (980±50 mN) and the mid-point deflection of the test specimen are monitored versus time using a computerized data acquisition system. The maximum bending stress at the midpoint of the test specimen is calculated from the dimensions of the test specimen, the distance between supports, and the load applied to the test specimen for loading times of 8.0, 15.0, 30.0, 60.0, 120.0 and 240.0 s. The stiffness of the test specimen for the specific loading times is calculated by dividing the maximum bending stress by the maximum bending strain.

[0166] b) Asphalt mix composition tests

[0167] Cyclic Compression Test (CCT)—According to TP Asphalt-StB Teil 25 B1, DIN EN 12697-25:2016

[0168] The uniaxial cyclic compression test is used to determine the deformation behavior of asphalt mix specimens. In this test, the specimen is tempered for 150±10 min at 50±0.3° C., which is the same temperature at which the test is carried out. After the tempering period, the specimen is set on the universal testing machine and loaded cyclically. Each cycle lasts 1.7 s, where the loading time is 0.2 s and the pause period is 1.5 s. The upper load applied is 0.35 MPa and the lower one is 0.025 MPa. The number of cycles and the deformation are recorded. The test ends either when 10,000 load cycles are completed or when the deformation is higher than 40%.

[0169] Indirect Tensile Strength Test—according to TP Asphalt-StB Teil 23, DIN EN 12697-23:2003

[0170] By the indirect tensile strength test, the fatigue behavior of asphalt mix specimens is determined. This is done by loading a cylindrical specimen across its vertical diametral plane at a specified rate of deformation (in this case 50±0.2 mm/min) and test temperature (in this case 20±2° C.). The peak load at failure is recorded and used to calculate the indirect tensile strength of the specimen.

[0171] Uniaxial Tensile Stress Test and Thermal Stress Restrained Specimen Test—according to TP Asphalt-StB Teil 46A (LTT=Low Temperature Tests) according to DIN EN 12697-46:2012 The uniaxial tensile stress test and thermal stress restrained specimen test are employed and carried out according to the European Standard EN 12697-46:2012 to determine the cold behavior of asphalt mix specimens: [0172] i) Thermal Stress Restrained Specimen Test (TSRST): while the deformation of the specimen is restrained, the temperature is reduced by a prespecified cooling rate. [0173] ii) Uniaxial Tensile Strength Test (UTST): in order to assess the risk of low-temperature cracking, the stress induced by thermal shrinkage is compared with the respective tensile strength.

[0174] Low-temperature cracking of asphalt mix compositions results from thermal shrinkage during cooling, inducing tensile stress in the asphalt mix. The low temperature behavior of pavement layers is mimicked by both tests.

[0175] Wheel Tracking Test according to TP Asphalt-StB Teil 22 DIN EN 12697-22:2003

[0176] Deformation (rut) depth of an asphalt mix composition subjected to cycles of passes of a loaded rubber wheel under constant and controlled temperature conditions are determined by the wheel tracking test. Typically, 10,000 cycles are carried out at 50° C.

[0177] Compactability according to TP Asphalt-StB Teil 10 DIN EN 12697-10

[0178] The compactability of an asphalt mix composition is determined as follows: a Marshall specimen is prepared from an asphalt mix composition according to EN 12697-30 using 100 blows of compaction to each side of the specimen. The thickness change is measured after each blow. Thereafter, a mathematical formula is derived from the experimental results. The respective formula parameters allow a characterization of the compactability of the investigated asphalt mix composition.

[0179] Recovery of Asphalt Binder from Asphalt Mix Compositions (Recovered Asphalt/Recovered Asphalt Binder)

[0180] With the help of an asphalt analyzer, around 3 kg of an asphalt mix composition is mixed with trichlorethylene. The aggregates are separated from the asphalt binder in a process that takes about 60 min. After the procedure is done, a solution of approximately 600 ml of trichlorethylene and asphalt is obtained. The solution is then distilled by partially immersing the rotating distillation flask of the rotary evaporator in a heated oil bath while the solution is subjected to a partial vacuum and a flow of air. This process has two phases. Phase 1 takes 60 min, is done at 90° C., under 40 kPa of pressure and a rotating speed of 75 rpm. Phase 2 is done at 160° C. under 2 kPa and a rotating speed of 75 rpm. Depending on the type of asphalt binder and the asphalt binder content of the asphalt mix, between 100-150 g of asphalt binder is recovered to then be subjected to testing as required.

[0181] a) Asphalt Binder Tests

[0182] Preparation of Long-Term Aged 50/70 Asphalt Binder and a Mixture thereof with an Unaged (Neat) Binder 70/100 with a Mixing Ratio of 75:25 by Weight

[0183] 2 kg long-term aged asphalt binder with a penetration grade of 50/70 was prepared by carrying out four subsequent RTFOT aging procedures, i.e. 4×75 min aging at 163° C. (300 min in total), employing a neat asphalt binder with a penetration grade of 50/70. With one run (300 min @ 163° C.) 35 g +/−0.5 g asphalt binder per bottle i.e. 8×35 g=280 g long-term aged binder can be prepared. After completing the aging runs, all long-term aged samples were placed in a single can, heated to 120-140° C. and stirred shortly to achieve homogeneity.

[0184] 1 kg of the homogenized long-term aged asphalt binder was blended with a neat asphalt binder having a penetration grade of 70/100. The mixing ratio was 75:25 (long-term aged:neat) by weight. Mixing was carried out at 120-140° C. under constant stirring for less than 1 min. The mixture was subsequently split into 120 g portions which served as samples for asphalt binder modifications.

[0185] Preparation of mixture of Isocyanate and Plasticizer:

[0186] For asphalt binder modifications, 500 g of a mixture of an isocyanate and plasticizer were prepared by mixing 150 g of polymeric diphenylmethane diisocyanate having an average isocyanate functionality of 2.7, designated in the following as “As20” with 350 g of a plasticizer (Diisononyl 1,2-cyclohexanedicarboxylic acid purchased as Hexamoll® DINCH) at room temperature under short stirring. Mixtures of As20 and Hexamoll® DINCH are denominated as “As20-DINCH mixtures” in the following.

[0187] General Procedure for the Preparation of Modified Asphalt Binder Compositions

[0188] Asphalt binder modifications employing either an unaged (neat) 50/70 binder (Table 1, sample 2) or a 75:25 mixture (by weight) of a long-term aged 50/70 binder and an unaged (neat) 70/100 (Table 1, sample 5 and 6) binder were carried out as follows:

[0189] 120 g of the respective asphalt binder was heated to 150° C. under air by placing the sample in the preheated oven. 1.8 g (1.5 wt. % referred to the employed amount of asphalt binder) or 6 g (5.0 wt. % referred to the employed amount of asphalt binder) of either As20 or the Isocyanate-plasticizer mixture (=3:7 mixture by weight of As20 : Hexamoll® DINCH) was added to the melted asphalt binder (see Table 1). The subsequently obtained mixture is stirred for a few seconds (<10 s) to achieve homogeneity. Thereafter, the samples were split into 35 g +/−0.5 g portions to carry out the rolling thin film oven test for the short-term aging. The test simulates the aging of asphalt during the mixing process, followed by the transportation of the asphalt mix composition to the construction site until the laydown of the asphalt mix. After aging, the modified asphalt is stored at room temperature or employed for further tests as follows: determination of the softening point/BTSV temperature (T.sub.BTSV/° C.; may alternatively be used instead of the softening point), BTSV phase angle (δ.sub.BTSV/°), and viscosity (@150° C.) (see Table 1).

TABLE-US-00001 TABLE 1 Viscosity, T.sub.BTSV and δ.sub.BTSV determined for different asphalt binders. Sample 1 2 3 4 5 6 Asphalt Asphalt 50/70 50/70 50/70 75 75 75 binder binder 1 aged* wt. % wt. % wt. % blend 50/70 50/70 50/70 aged* aged* aged* Asphalt — — — 25 25 25 binder 2 wt. % wt. % wt. % 70/100 70/100 70/100 unaged unaged unaged As20 additive/ —  1.5 — 1.5 — wt. % As20-DINCH — — — 5.0 mixture/wt. % (1.5/3.5) (As20/wt. %/ Hexamoll ®- DINCH/wt. %) Viscosity@150° 239 550   673 650 1753 689 C./mPas Softening point 49.6 60.8 66.7 65.6 77.6 62.2 “ring and ball method”/° C. T.sub.BTSV/° C. 49.6 60.4 66.1 65.9 74.7 61.5 δ.sub.BTSV/° 82.0 76.8 77.4 76.2 67.3 68.7 *long-term aged asphalt binder prepared by four subsequent RTFOT aging runs (see above)

[0190] The workability of an asphalt mix composition is directly linked to the viscosity of the asphalt binder i.e. highly viscous asphalt binders cause compaction issues during asphalt mix laydown. It is known to the art that the aging of asphalt binders leads to an increase of both the binder viscosity and the softening point/BTSV temperature. This in turn means on the one hand that asphalt mix compositions containing a high ratio of aged binder, i.e. a high ratio of reclaimed asphalt pavement (RAP), are more difficult to compact/process. On the other hand, an increase of the softening point/BTSV temperature means that the asphalt mix is getting harder i.e. the stability at higher temperatures is increased. When looking at the BTSV phase angle of asphalt binders, lower phase angles reflect better properties in terms of flexibility/elasticity/less brittleness of the asphalt mix and thus better performance. Typically, BTSV phase angles lower than 75° are characteristic for modified asphalt (e.g. polymer modified bitumen; see “Modifzierung bestimmen”, M. Sutor-Fiedler, Asphalt & Bitumen May 2017).

[0191] As can be seen in Table 1, the modification of an unaged asphalt binder 50/70 with As20 leads to an increase both in viscosity and softening point/BTSV temperature. Moreover, the phase angle is decreased. Accordingly, a better performance of a respective asphalt mix compositions containing such a binder can be expected.

[0192] Long-term aging of an unmodified asphalt binder 50/70 (sample 3) leads a strong increase of viscosity and, in particular, softening point/BTSV temperature. To counteract, unmodified softer asphalt binder as for example a pen 70/100 can be added which is demonstrated by sample 4. The 75:25 ratio by weight is typical of an asphalt mix composition containing 75% RAP. Such mixtures are for example used for subbase layers.

[0193] When modifying a 75:25 mixture (by weight) of a long-term aged 50/70 binder and an unaged (neat) 70/100 binder (sample 5), viscosity and softening point/BTSV temperature expectedly increase and BTSV phase angle decreases. The viscosity of the accordingly modified binder is in the range of polymer modified bitumen. Due to the high viscosity, compaction issues with asphalt mixes containing such an asphalt binder can be expected. It was surprisingly found that by employing a combination of a thermosetting reactive compound (As20) with a plasticizer (Hexamoll® DINCH), the viscosity and the softening point/BTSV temperature of the asphalt binder can be reduced significantly i.e. improving the workability of a corresponding asphalt mix (sample 6). Additionally, the phase angle is not influenced negatively, i.e. the phase angle increases only slightly when compared with sample 5. Interestingly, the achieved BTSV performance characteristics is typical of a polymer modified bitumen (e.g. PmB 25/55-55).

[0194] Consequently, an asphalt mix composition containing a binder according to the example, the performance is expected to be boosted strongly and a good workability of the asphalt mix is obtained at the same time while a high ratio of reclaimed asphalt pavement material can be realized for the pavement.

[0195] Additional benefits are for example: reduction of the laydown temperatures due to the lowered viscosity and thereby lower bitumen emissions (bitumen vapors and aerosols), increase of the RAP content of pavement layers where the use of RAP is limited (e.g. base layers where only 50 wt. % RAP is allowed in combination with polymer modified bitumen), employ RAP material where the softening point of the binder is very high (i.e. less limitation in terms of the age of RAP material), reduce dimension of subbase layer due to increased stability and thereby save costs and raw materials and reduce CO.sub.2 emissions.

[0196] b) Asphalt Mix Composition Tests

[0197] Abovementioned asphalt binder tests with ideal mixtures of unaged and aged asphalt binders already demonstrate the advantages of the As20-DINCH mixture (additive according to the invention). However, ideal binder blends do not represent real-life conditions being present in asphalt mix compositions. There, aged asphalt contained in RAP material adheres to aggregates and is not entirely and homogeneously mixed with unaged (neat) asphalt binder which is added during the mixing process. Moreover, asphalt performance data does not always mirror asphalt mix performances. Therefore, asphalt mix composition tests with/without (w/o)/with reference additive were carried out. The reference additive is a state-of-the art rejuvenator which is used to reduce the softening point of RAP material, restore material properties and thereby enable the use of higher amounts of RAP.

[0198] Procedure for the Preparation of Asphalt Mix Compositions

[0199] For each of the four samples listed in Table 2, two batches with a total mass of 40 kg (=aggregates+RAP material; asphalt binder and additive come on top, see Table 2) per batch were prepared. In case of example 1 and comparative example 1, the asphalt binder 70/100 was premixed with the As20-DINCH mixture (additive according to the invention) and reference additive, respectively. The batch size of each of the pre-mixes was 1200 g and prepared as follows: i) asphalt binder 70/100 was melted by heating it to 130-150° C., ii) 972 g melted asphalt binder was weighted into a separate can, iii) 228 g of the additive according to the invention (3:7 mixture of As20 :Hexamoll® DINCH) or the reference additive was added to the melted asphalt binder at 130-150° C. under stirring, iv) stirring was carried out for less than 1 minute to achieve homogeneity, v) the as-prepared pre-mix was thereafter immediately used for the preparation of corresponding asphalt mix compositions. The employed reference additive is a commonly used and commercially available rejuvenator which reduces the softening point of asphalt binders in RAP-containing asphalt mix compositions and the viscosity of respective asphalt mix compositions in order to provide a good workability of the mix during laydown.

[0200] Aggregates, RAP, asphalt binder/asphalt binder additive premix were weighed for each asphalt mix composition as given in Table 2 and subsequently stirred in a laboratory mixer (allows a maximum batch size of 70 kg) for 10 min at 170° C. Aggregate sieve fractions, total asphalt binder and RAP content correspond to an AC 22 TS pavement layer. The asphalt content of RAP material was 3.8 wt. %. The additive amount of 5 wt. % refers to the total asphalt content (asphalt from RAP+unaged (neat) asphalt) of the unmodified variant (see reference 2: 1140 g binder from RAP+404 g neat binder 70/100). In order to keep the volume of the modified binder approximately constant (example 1 and comparative example 1), the amount of neat binder is reduced by the amount of the additive (i.e. 76 g less when compared with reference 2).

[0201] After mixing, 20 kg portions of the prepared asphalt mix compositions were filled into buckets and stored for one hour at 150° C. in an oven (preheated to 150° C. before samples were placed inside). After storage, Marshall specimens were prepared for compactability tests. Moreover, two asphalt mix plates were prepared for cyclic compression tests (CCT) and low temperature tests (LTT). Asphalt binder characteristics (T.sub.BTSV, δ.sub.BTSV, BBR) were determined from recovered asphalt binders of the corresponding asphalt mix compositions (see description for recovery process above). Results of asphalt binder and asphalt mix tests are compiled in Table 3.

TABLE-US-00002 TABLE 2 Recipes for different asphalt mix compositions. Aggregate sieve fractions, total asphalt binder and RAP content correspond to an AC 22 TS pavement layer. The additive amount of 5 wt. % refers to the total content of asphalt (asphalt from RAP + unaged (neat) asphalt) of the unmodified variant as given for reference 2. The asphalt content of RAP material was 3.8 wt. %. Sample: 75 wt. % RAP + 75 wt. % RAP + 5 wt. % As20- 5 wt. % reference 50 wt. % RAP 75 wt. % RAP DINCH additive w/o additive w/o additive mixture comparative Reference 1 Reference 2 Example 1 Example 1 Content Mass Content Mass Content Mass Content Mass Grain size Type [%] [g] [%] [g] [%] [g] [%] [g] RAP 22 — 50 20000  75  30000  75 30000  75  30000   0/16 16/22 Greywacke — — 9 3600 9 3600 9 3600  5/22 Greywacke 22 8800 3 1200 3 1200 3 1200 2/5 Greywacke 8 3200 — — — — — — 0/1 Sand 8 3200 5 2000 5 2000 5 2000 0/2 Limestone 9.5 3800 8 3200 8 3200 8 3200 Filler Limestone 2.5 1000 — — — — — —  70/100 Asphalt 1.9  775   1.0  404 0.81  328   0.81  328 As20-DINCH mixture — — — — 0.19  76 — — Reference additive — — — — — —   0.19  76

TABLE-US-00003 TABLE 3 Asphalt binder and asphalt mix performance characteristics of prepared asphalt mix compositions (cf. Table 2). 75 wt. % 75 wt. % RAP + 5 RAP + 5 50 wt. % 75 wt. % wt. % wt. % RAP w/o RAP w/o As20- reference Additive Additive DINCH additive Reference Reference mixture comparative Sample: 1a 1b Example 1 Example 1 Asphalt binder tests carried out with recovered asphalt binder (recovery process see above) BTSV temperature 65.1 69.3 67.8 60.2 T.sub.BTSV/° C. BTSV phase angle 72.6 72.0 68.0 72.7 δ.sub.BTSV/° Low temperature −16.8 −15.9 −18.6 −21.3 behavior: stiffness at 300 MPa via BBR method/° C. Low temperature −17.5 −14.6 −19.8 −22.4 behavior: (m-value at 0.3) via BBR method/° C. Asphalt mix composition tests Compactability 37.5 35.1 35.1 36.5 [21 Nm] at 140° C. Compactability 38.1 42.7 41.6 44.4 [21 Nm] at 115° C. Compactability 43.3 48.0 44.4 46.8 [21 Nm] at 100° C. Cyclic Compression 3616 4619 10000 4178 Test (CCT) Inflection point/cycles Cyclic Compression 11.5 1.6 1.6 2.9 Test (CCT) deformation rate at inflection point/‰ Low Temperature 4.25 4.17 5.20 4.26 Tests Tensile strength/MPa Low Temperature −25.4 −22.6 −26.5 −28.0 Tests break temperature/° C.

[0202] Asphalt Binder Performance

[0203] As can be seen in Table 3, the softening point/BTSV temperature of the asphalt binder increases for asphalt mix compositions if the ratio of RAP is increased (compare reference 1a and 1b). Moreover, the low temperature behavior gets worse as expected (stiffness of 300 MPa or m-value of 0.3 reached at higher temperatures).

[0204] When employing the As20-DINCH mixture (5 wt. %) for an asphalt mix composition containing 75 wt. % RAP (example 1), the softening point/BTSV temperature can be decreased from 69.3° C. to 67.8° C. Additionally, the BTSV phase angle is strongly decreased from 72.0° to 68.0° and the low temperature behavior is improved markedly (stiffness of 300 MPa or m-value of 0.3 reached at lower temperatures when compared with reference 1b). Due to the lower BTSV phase angle, much better properties in terms of flexibility/elasticity/less brittleness of the asphalt mix and thus better performance is expected.

[0205] The reference additive (comparative example 1) decreases the softening point/BTSV temperature of the asphalt binder strongly from 69.3° C. to 60.2° C. The BTSV phase angle is increased slightly i.e. the performance of the corresponding asphalt mix composition is expected to be worse, not even being at the same level of the unmodified variant (reference 1b).

[0206] Asphalt Mix Performance

[0207] Asphalt mix compositions tests are in line with findings from asphalt binder tests. The following conclusions can be drawn: [0208] The additive according to the invention (As20-DINCH mixture) outperforms the reference additive in terms of deformation behavior (determined by CCT) of the respective asphalt mix composition. The deformation behavior of the asphalt mix composition containing the reference additive is even worse than the reference without additive. This is in line with findings from binder investigations. [0209] The low temperature behavior of example 1 and comparative example 1 is almost at the same level, both outperform the reference example without additive. [0210] Due to the viscosity decrease of the asphalt binder (see findings from asphalt binder tests), the additive according to the invention (As20-DINCH mixture) enables a better compactability at low temperatures when compared with reference 1b and comparative example 1 (see Table 3, 115° C. and 100° C.; lower values correlate with a better compactability of the asphalt mix composition). Therefore, the workability of the mix is improved by the additive according to the invention (As20-DINCH mixture). Moreover, a temperature reduction at asphalt mix production and laydown is enabled.

[0211] 5c) Experiments at an (Batch) Asphalt Mixing Plant

[0212] Results from laboratory investigations were transferred to real scale by carrying out experiments at an (batch) asphalt mixing plant as described in the following.

[0213] Preparation of an Asphalt Mix Composition Containing 50 wt. % RAP in an (Batch) Asphalt Mixing Plant—No Additive is Used (Comparative Example 2)

[0214] The batch size is 3500 kg. The granulometric curve of the asphalt mix composition was an AC 22 BS. The asphalt mix comprises 50 wt. % reclaimed asphalt (aggregates+asphalt) and 50 wt. % virgin material. The total asphalt content in the mixture of asphalt and aggregates was 4.5 wt. %, i.e. 157.5 kg asphalt per 3500 kg batch. 84 kg of 157.5 kg asphalt originate from reclaimed asphalt (4.8 wt. %) and the remaining 73.5 kg stem from the addition of unmodified (paving grade) asphalt pen 70/100 (a needle penetration of 7-10 mm according to DIN EN 1426). The grain size distribution was adjusted as given in Table 4 whereat the bypass describes the mixture of virgin granular material (without filler) complying with an AC 22 BS pavement layer and being adjusted manually by the plant operator. The analysis of sieve fractions and binder content after asphalt mix production is given in Table 5.

[0215] Virgin granular material and reclaimed asphalt were preheated separately from each other and subsequently mixed together for 6 s (pre-mix). Heating power and mixing time were adjusted such that a temperature of 140-155° C. of the final asphalt mix composition can be achieved. 73.5 kg unmodified (paving grade) asphalt pen 70/100 being preheated to a temperature of 165-175° C. was weighed into the asphalt balance. The asphalt together with the premixed material (mixture of virgin aggregates and reclaimed asphalt having a temperature of 170° C.) were added to the mixing unit (double shaft compulsory mixer) and the resulting mixture is further mixed, wherein the total duration of further mixing is 30 s. The temperature of the resulting final asphalt mix composition at this stage of the process was determined to be 145-150° C. Subsequently, the asphalt mix composition was released to the silo and then directly into a wheel loader (i.e. no storage time). Subsequently, samples were taken for asphalt binder tests (carried out after asphalt binder recovery as described above) and asphalt mix composition tests (Table 6).

[0216] Preparation of an Asphalt Mix Composition Containing 50 wt. % RAP in an (Batch) Asphalt Mixing Plant—5 wt. % As20-DINCH Mixture (Additive According to the Invention) is Employed (Example 2)

[0217] The asphalt mixing plant was equipped with a customized dosing system (heatable dosing line, dosing pump) which allows the dosage of the additive according to the invention (3:7 mixture of As20 :Hexamoll® DINCH) to the asphalt balance (stirred vessel) of the asphalt mixing plant. Furthermore, the asphalt balance was equipped with a stirrer which is engaged when i) the As20-DINCH mixture is dosed and ii) a minimum filling level of 20 kg asphalt is reached. The amount and speed of additive dosage as well as mixing is controlled via the process control system of the asphalt mixing plant.

[0218] The batch size is 3500 kg. The granulometric curve of the asphalt mix composition was an AC 22 BS. The asphalt mix comprises 50 wt. % reclaimed asphalt (aggregates+asphalt) and 50 wt. % virgin material. The total asphalt content (including the additive, since it is modifying the binder) in the mixture of asphalt and aggregates was 4.5 wt. %, i.e. 157.5 kg (modified) asphalt per 3500 kg batch. 84 kg of 157.5 kg asphalt originate from reclaimed asphalt (4.8 wt. %), 65.5 kg stem from the addition of unmodified (paving grade) asphalt pen 70/100 (a needle penetration of 7-10 mm according to DIN EN 1426), and 8.0 kg As20-DINCH mixture were added. The amount of additive was calculated on the basis of the unmodified variant given in comparative example 2, i.e. 5.0 wt. % with respect to the total (unmodified) binder (=asphalt stemming from reclaimed asphalt +added unmodified (paving grade) asphalt pen 70/100 =157.5 kg). In order to keep the volume of the modified binder of example 2 approximately constant, the amount of neat binder is reduced by the amount of the As20-DINCH mixture i.e. 8.0 kg less when compared with comparative example 2.

[0219] The grain size distribution was adjusted as given in Table 4 whereat the bypass describes the mixture of virgin granular material (without filler) complying with an AC 22 BS pavement layer and being adjusted manually by the plant operator. The analysis of sieve fractions and binder content after asphalt mix production is given in Table 5.

[0220] Virgin granular material and reclaimed asphalt were preheated separately from each other and subsequently mixed together for 6 s (pre-mix). Heating power and mixing time were adjusted such that a temperature of 140-155° C. of the final asphalt mix composition can be achieved. 65.5 kg unmodified (paving grade) asphalt pen 70/100 being preheated to a temperature of 165-175° C. was weighed into the stirring vessel (=asphalt balance). 8.0 kg of the As20-DINCH mixture is then added to the asphalt under stirring (1500 rpm) and the resulting mixture is then further stirred, wherein the dosage speed is set between 0.1 L/s and 2.0 L/s and the time of further stirring is set to 10 s. The resulting modified asphalt together with the premixed material (mixture of virgin aggregates and reclaimed asphalt having a temperature of 170° C.) were added to the mixing unit (double shaft compulsory mixer) and the resulting mixture is further mixed, wherein the total duration of further mixing is 30 s. The temperature of the resulting final asphalt mix composition at this stage of the process was determined to be 145-150° C. Subsequently, the asphalt mix composition was released to the silo and then directly into a wheel loader (i.e. no storage time). Subsequently, samples were taken for asphalt binder tests (carried out after asphalt binder recovery as described above) and asphalt mix composition tests (Table 6).

TABLE-US-00004 TABLE 4 Asphalt mix compositions prepared in a (batch) asphalt mixing plant with and w/o additive according to the invention (3:7 mixture of As20:Hexamoll ® DINCH). 50 wt. % 50 wt. % RAP w/o RAP 5 wt. % As20-DINCH As20-DINCH mixture mixture Reference 2 Example 2 Sample: kg/t kg/t Grain size Type asphalt mix % asphalt mix % RAP 220/16 500 50 500 49.9 Bypass Greywaeke 474 47.4 476 47.5 Filler Limestone 5 0.5 5 0.5 70/100 Asphalt 21 2.1 18.7 1.9 binder As20-DINCH mixture — — 2.3 0.2

TABLE-US-00005 TABLE 5 Sieve fraction analysis and asphalt binder content of prepared asphalt mix compositions. 50 wt. % 50 wt. % RAP w/o RAP 5 wt. % As20-DINCH As20-DINCH mixture mixture Reference 2 Example 2 Grain size classes Asphalt mix Grain size classes Asphalt mix mm wt. % mm wt. % 22.4-31.5 1.5 22.4-31.5 3.5 16.0-22.4 20.4 16.0-22.4 20.7 11.2-16.0 22.1 11.2-16.0 21.1  8.0-11.2 8.5  8.0-11.2 8.1 5.6-8.0 10.7 5.6-8.0 7.8 2.0-5.6 16.5 2.0-5.6 16.1 0.125-2.0  12.2 0.125-2.0  14.7 0.063-0.125 0.9 0.063-0.125 0.8 <0.063 7.4 <0.063 7.1 Asphalt binder 4.4 Asphalt binder 4.1

TABLE-US-00006 TABLE 6 Asphalt mix compositions tests and asphalt binder tests carried out with samples produced in a (batch) asphalt mixing plant with and w/o additive according to the invention (3:7 mixture of As20:Hexamoll ® DINCH). 50 wt. % 50 wt. % RAP w/o RAP 5 wt. % As20-DINCH As20-DINCH mixture mixture Sample: Reference 2 Example 2 Asphalt binder tests carried out with recovered asphalt binder (recovery process see above) BTSV temperature 54.6 61.7 T.sub.BTSV/° C. BTSV phase angle 75.9 66.5 δ.sub.BTSV/° Recovery at 3.2 kPa/% 3.6 34.4 via MSCR test J.sub.nr at 3.2 kPa/1/kPa 1.55 0.26 via MSCR test Low temperature −8.4 −5.7 behavior: stiffness at 300 MPa via BBR method/° C. Low temperature −15.4 −15.6 behavior: (m-value at 0.3) via BBR method/° C. Asphalt mix composition tests Asphalt content/% 4.3 4.1 Air void content/% 5.7 5.1 Hamburg Wheel Test 3.67 2.23 rutting depth/mm Compactability 48.8 43.5 [21 Nm] at 100° C. Cyclic Compression 3590 8854 Test (CCT) inflection point/cycles Cyclic Compression 4.8 0.1 Test (CCT) deformation rate at inflection point/‰ Low Temperature Tests 4.2 2.9 tensile strength/MPa Low Temperature Tests −26.4 −31.2 break temperature/° C.

[0221] Asphalt Binder Performance

[0222] When employing the additive according to the invention (As20-DINCH mixture) for an asphalt mix composition containing 50 wt. % RAP (example 2) at an asphalt mixing plant, the BTSV temperature is increased from 54.6° C. to 61.7° C. (Table 6). Accordingly, comparably low softening points are increased leading to a better asphalt mix stability at high temperatures (example 2), and quite high softening points (see example 1 and reference 1b above) are decreased leading a softer material. Additionally, the BTSV phase angle is strongly decreased from 75.9° to 66.5° and the low temperature behavior remains on a similar level (cf. reference 2). Due to the lower BTSV phase angle, better properties in terms of flexibility/elasticity/less brittleness of the asphalt mix and thus better performance is expected. Moreover, the J.sub.nr value (via MSCR test) was decreased from 1.55 1/kPa to 0.26 1/kPa, i.e. the binder is then specified for extreme traffic load (>30 million ESALs and standing traffic for J.sub.nr<0.5; 1 ESAL(Equivalent Single Axle Load)=80 kN) instead of only heavy load (10-30 million ESALs or slow-moving traffic for J.sub.nr<2) as applies for comparative example 2.

[0223] Asphalt Mix Performance

[0224] As can be seen from asphalt mix performance tests (Hamburg wheel tracking test, compactability, CCT, LTT), the according to the invention (As20-DINCH mixture) markedly outperforms the comparative example (Table 6): better compactability/workability of the mix, better rutting and fatigue behavior, better low temperature performance. This is in line with findings from asphalt binder tests described before. Interestingly, in contrast to asphalt binder tests, the low temperature behavior as determined from asphalt mix low temperature tests (LTT) could even be improved since the break temperature was decreased from −26.4° C. to −31.2° C.

[0225] Concluding, both asphalt binder tests and asphalt mix composition tests confirm findings from laboratory investigations on industrial scale and demonstrate the performance and advantages of the additive according to the invention (As20-DINCH mixture).