BITUMINOUS COMPOSITIONS

Abstract: A composition useful as a pavement material comprising a mixture of asphalt and a polymer of an alpha -olefin, or an interpolymer of an alpha -olefin, and at least one copolymer selected from the group consisting of an alpha , beta -unsaturated carboxylic acid, a ionomer of an alpha , beta -unsaturated carboxylic acid, a vinyl ester of alkanoic acid, and carbon monoxide. The composition may contain also an aggregate and/or a filler.

Description: BITUMINOUS COMPOSITIONS The use of petroleum residuum such as asphalt as a paving material and other construction material is well known. It is also well known to blend various polymeric materials into the asphalt to improve certain properties. For example, polyolefins have been used; but, as pointed out in U.S. Patent 4,240,946 the addition of such polyolefins increases the viscosity of such blends at working temperatures thus necessitating 0 special mixing and homogenizing procedures. The use of such polyolefins, however, is greatly desired since they help maintain the integrity of the asphalt when subjected to elevated temperatures such as when used aspavement material. It would be helpful if a 5 polyolefin material were discovered which could be easily blended with the asphalt at normal working temperatures such as from 270°F to 340°F (132°C to 171°C) without significantly increasing the viscosity of the Q mixture above the normal level while imparting improved stability at environmental temperatures. The present invention concerns such a discovery. Unique physical properties and an abundant 5 supply have established asphalt as a major raw material for use in industrial applications that involve structural adhesive and waterproof protective films. The major markets for these industrial applications are road paving and roofing respectively. Both asphalt cement and mineral filled roofing asphalt can comprise a mixture of asphalt with silica or limestone based minerals. Consequently, chemical and physical factors which can influence the asphaltic coating of minerals are operative in both applications. Residual oils and/or bituminous materials, such as asphalt, used in the preparation of pavements do not coat and adhere well to mineral aggregates unless the aggregate is substantially dry, and, for this reason, in conventional pavements it may be necessary to dry the mineral aggregate prior to blending with the bituminous material. Mineral aggregates employed in road pavement range in character from hydrophilic to hydrophobia. In general, siliceous and acidic minerals, such as sands and gravels, tend to be hydrophilic while calcareous, alkaline minerals, such as limestone, tend to be more hydrophobia. It has been observed that the mineral aggregates appear to have a greater attraction for water than for oil or bitumens and that it is difficult to obtain complete or satisfactory coating of aggregates by oil or bitumen when water is present. Furthermore, even though satisfactory coating may be obtained by using dry aggregates, the oil or bitumen tends to be displaced if water enters the pavement or road. One approach which has been used to decrease the severity of the problems attributed to poor adhesion between the aggregate and bitumens and/or stripping of the bitumen from the aggregate due to the presence of moisture has been to include an additive (hereinafter referred to as an antistripping agent) in the bitumen prior to combination with the aggregate. These antistripping agents serve to enhance the coating of the aggregate by bitumens and retard displacement of the aggregate-bitumen bond by water. The art discloses several antistripping agents which are useful as additives in bitumens and asphalts. For example, U.S. Patent 2,759,839 to Crews et al. discloses the use of certain amines as antistripping agents. U.S. Patent No. 3,985,694 teaches the use of terpenic resins and interpolymers of ethylene, methylacrylate and an organic acid improves certain properties of asphalt compositions such as adhesion to aggregates. U.S. Patent No, 3,867,162 discloses the use of tall oil as an adhesion promoter in bituminous emulsions. U.S. Patent No. 3,615,797.discloses the use of tertiary amines as bitumen additives which improve the adhesion properties of the bitumen. U.S. Patent No. 3,978,014 discloses the use of bituminous compositions containing two polymeric materials; one which improves the resistance of the material to flow under elevated temperatures, and the second causes improved adhesion to other materials. The second polymer is characterized by having a molecular weight of at least 10,000, a solubility parameter (defined in Dutch Patent Application 6,706,408) of between 7.8 and 8.8 and a crystallinity of less than 60 percent at 25°C. The second polymer is disclosed to include for example polyethylene, polybutadiene, chlorinated polyethylene, 5 ethylene, ethylacrylate copolymers, ethylene vinylacetate and the like. The polymers must each be employed in a minimum amount of 4 weight percent of the composition. 10 U.S. Patent No. 4,430,127 discloses the use of an expoxylated polyamine to provide adhesion between aggregate materials and the bitumen. U.S. Patent 3,364,168 discloses a blend of low 15 molecular weight, low density polyethylene, refined grade lube oil and petroleum resin provides a material which can be employed as road paving substance and the like. 20 One aspect of the present invention is based on the discovery that improved adhesion of aggregate and bitumen can be achieved by incorporating small amounts of certain α-olefin copolymers into the mixture. 25 The present invention comprises a composition comprising a bituminous material from 90 to 99.9 percent and a copolymer of an α-olefin (e.g. ethylene) an α,β-ethylenically unsaturated carboxylic acid (e.g. acrylic acid) from 0.1 to 10 percent or the neutralized 30 salt thereof (ionomer); wherein the copolymer contains from 5 to 30 percent by weight of the α,β-ethylenically unsaturated carboxylic acid or ionomer and 95 to 70 percent by weight of the α-olefin. The composition is m m substantially free of α-olefin/ester copolymers since these tend to decrease the adhesive characteristics of the composition to the mineral aggregates. The above composition is mixed with from 90 to 96 percent by weight of mineral aggregate to form paving, roofing, and other type materials. The present invention concerns a composition which comprises: a bituminous material of from 99 to 50 parts by weight and from 1 to 50 parts by weight of a olefinic polymer selected from the group consisting of homopolymers and interpolymer of an α-olefin and at least one comonmer selected from the group consisting of α,β-unsaturated carboxylic acid, ionomer of α,β-unsaturated carboxylic acid, vinyl ester of alkanoic acids, and carbon monoxide, wherein said polymer has a melting point between 140°F and 350°F (60°C and 176.7°C), a melt flow index ranging from 50 g/10min to 3000 g/10 min and is dispersible in said bituminous material. The comonomer should render the olefin more polar. Olefin homopolymers include polymers of a single olefin such as ethylene, as well as interpolymers of more than one α-olefin such as ethylene-butylene, ethylene octylene and the like. The comonomer is selected from the group consisting of an α,β-ethylenically unsaturated carboxylic acid, or the neutralized metallic salts thereof (known in the art as ionomers); vinyl esters of alkanoic acids; carbon monoxide and various interpolymers containing one or more of the aforementioned comonomers and blends of two or more such interpolymers. The polymers have a sharp melting point which is higher than the normal temperature to which the asphalt is subjected to in use (e.g., pavement under summer conditions) and less than the temperature employed in applying the asphalt material. A melting point of between 140°F (6θ°C) and 350°F (176.7°C) is useful. The polymers also are characterized by having a melt flow index (determined by ASTM D-1238-Sch.E) ranging from 50 g/10 min to 3000 g/10 min, preferably 100 g/10 min to 3000 g/10 min. The ratio of polar monomer to olefin monomer in the interpolymer is within a range that the interpolymer remains compatible (dispersible) with the asphalt material and does not separate from the blend. 10 In another aspect the present invention concerns a composition comprising a bituminous material from 90 to 99.9 percent and at least one interpolymer of an α-olefin (e.g. ethylene) an α,β-ethylenically 15 unsaturated carboxylic acid (e.g. acrylic acid) from 0.1 to 10 percent or the neutralized salt thereof (ionomer); wherein the interpolymer contains from 5 to 30 percent by weight of the α,β-ethylenically mm unsaturated carboxylic acid or ionomer thereof and 95 to 70 percent by weight of the α-olefin. The composition is substantially free of α-olefin/ester copolymers since these tend to decrease the adhesive characteristics of the composition to the mineral 25 aggregates. The above composition is mixed with from 90 to 96 percent by weight of mineral aggregate to form paving, roofing, and other type materials. The bituminous material employed in the 30 practice of the present invention is not critical. Any bitumen, asphalt or crude residuum containing ' asphaltenes can be employed. U.S. Patent 3,317,447 contains a good description of useful bituminous materials In general, the asphalts which can be 35 employed include conventional petroleum asphalts, natural asphalts, gilsonite, air blown asphalts, coal tar and other similar materials. The asphalts are characterized by having penetration grades of up to 300 as measured by ASTM Method D5. Preferred asphalts are the normal paving asphalts e.g. AC5, AC10, AC20, and AC30. AC indicates asphalt cement and the number indicates viscosity at 140°F in poise divided by 1000 This corresponds to asphalt cement (AC) having viscosity at 60°C of 0.5Pa-s, 1Pa-s, 2Pa-s and 3Pa-s. The homopolymers employed in the practice of the invention are selected from low density, medium density and linear low density and high density polyolefins having a melting point and melt flow index as set forth herein. Polyethylene and polyethylene polymers containing an additional α-olefin (C -Cg) are preferred polymers. The interpolymers useful in the practice of the invention are prepared from the reaction of an α-olefin and a comonomer which adds polar characteristics to the olefin. The olefin preferably is a C- j to Cγ alpha olefin. Ethylene is preferred. The comonomer is a material which adds polar characteristics to the α- olefin and is selected from the group consisting of α,β-ethylenically unsaturated carboxylic acids, ionomers, esters of such acids, carbon monoxide and interpolymers containing two or more of such comonomers and blends of two or more such interpolymers. The comonomers are employed in an amount which provides an interpolymer which has a sharp melting point between 140°F (60°C) and 350°F (176.7°C) the normal working temperature used in preparing the bituminuous material for use as paving material, roofing material or the like. The interpolymer can have a Melt Flow Index(determined by ASTM D 1238-Sch.E) ranging from 1.5g/10 min to 6,000 g/10 min or higher, preferably 50 g/10 min to 3000 g/10 min, most preferably 100 to 3000. The mole percent of comonomer in the interpolymer can range over a wide span. The amount will depend on the particular comonomer employed. However, the maximum amount will be such that the interpolymer does not become incompatable with the bituminous material and tend to separate therefrom. This can be readily ascertained by simple laboratory testing prior to 10 formulating the blend for use as a paving material or the like. The interpolymer preferably has a melt flow index (MI) and percentage of copolymers which will cause the interpolymer to form a homogenous blend with 15 the bituminous material at a temperature of between 200°F (93°C) and 300°F (149°C). Preferred copolymers are CO/ethylene copolymer containing, as percent by weight from 1 to 30 percent CO, preferably from 1 to 10 percent CO. Other preferred interpolymers contain 20 ethylene and acrylic and/or methacrylic acid in an amount ranging from 1 to 30 percent, preferably 5 to 30 percent, more preferably 1 to 25 percent, most prefereably 8 to 20 percent of acrylic and/or methacrylic acid. These interpolymers are well known 25 in the art as well as their manufacture. U.S. Patents 4,351,931; 3,520,861; 4,252,924; and 3,969,434 describe such interpolymers and their method of manufacture. Specific examples of comonomers which can be 30 employed include, for example, acrylic acid, methacrylic acid, crotonic acid, and monomer thereof, vinyl acetate, vinyl butyrate, lower alkyl or hydroxyalkyl (C- | to CQ) esters of the aforementioned -,,- ethylenically unsaturated carboxylic acids (e.g. methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, etc.); and the like. The neutralizing cation for the ionomers are usually Na, Mg or Zn. Other mono-, di- and trivalent metals such as Ca, Al, K and Li can be used. Particularly preferred interpolymers are ethylene/acrylic acid polymer containing 3 percent by weight of acrylic acid and having a melt flow index of 2600 g/10 min; ethylene/acrylic acid containing 8 percent by weight acrylicacid and having a melt flow 10 index of 600; and an ethylene/CO polymer containing 8 percent by weight of CO and having a melt flow index of 250. These polymers are well known in the art as well as their method of manufacture. U.S. Patents 15 4,351,931; 3,520,861;. 4,252,924; and 3,969,434 describe such polymers and their method of manufacture. Interpolymers of an α-olefin (e.g., ethylene) 20 and carbon monoxide are well known. Specific interpolymers of an α-olefin and carbon monoxide (CO) with or without additional polar comonomers include, olefin polymers which have carbon monoxide groups incorporated into the polymer chain. A sole olefin or 25 a plurality of olefins may be used along with the carbon monoxide in preparing the polymers. Preferably the olefin monomer is ethylene (sometimes including a small proportion of a C3-C3 aliphatic olefin for property modification). The olefin monomer can also 30 include an unsaturated organic acid having 3 to 8 carbon atoms, such as acrylic acid, methacrylic acid, 1-buteneic acid, and the like; alkyl ester or metal salts of these acids may also be used, such as ethyl mm acrylate, methyl methacrylate, 2-ethyl hexyl acrylate, sodium acrylate, potassium methacrylate, and the like. Hydrogenated CO containing olefin polymers (hydrogenation creates C-OH groups along the polymer chain) are included here, such as hydrogenated ethylene/carbon monoxide copolymers. U.S. 2,495,292 discloses methods of hydrogenating such CO groups in a polymers chain. It has been known for many years that olefins, e.g. ethylene, and carbon monoxide, can be copolymerized or terpolymerized. The following listed patents are believed to be representative of the art pertaining to interpolymers of carbon monoxide and monoolefins: U.S. 2,495,292 U.S. 2,495,286; U.S. 2,497,323 U.S. 2,641,590 U.S. 3,083,184; U.S. 3,248,359 U.S. 3,530,109 U.S. 3,676,401; U.S. 3,689,460 U.S. 3,694,412 U.S. 3,780,140; U.S. 3,835,123 U.S. 3,929,727 U.S. 3,948,832; U.S. 3,948,873 U.S. 3,948,850 U.S. 3,968,082; U.S. 3,984,388 U.S. 4,024,104 U.S. 4,024,325; U.S. 4,024,326 U.S. 4,139,522 U.S. 4,143,096; and U.S. 4,304,887. The amount of polymer to be used in the asphalt blend can range from 1 to 50 percent by weight, preferably from 3 to 20 percent by weight of polymer is employed. When improved adhesion of aggregate and bituminous material is desired the amount of interpolymer to be used in the bitumen blend can range from about 0.1 to about 10 percent by weight, preferably from about 0.1 to about 5 percent and most preferred about 1 percent or less is employed. The blend is substantially free of copolymers of an α- olefin and an acetate such as vinyl acetate since these copolymers tend to decrease the adhesiveness of the blend to mineral aggregates. However, surprisingly, the absence of the acetate does not detract from the other favorable properties of the blend such as elasticity of the blend. The polymer is admixed with the bituminuous material in any convenient manner employing the equipment which is normally used in paving, roofing and other construction projects. The bituminuous material and the polymer are hot mixed at a temperature of from at least 140°F (60°C) up to the decomposition temperature of the polymer. The polymeric material component as finely divided solid or in solution, in a solvent e.g. with benzene or toluene, is mixed into molten asphalt. Other additives can be mixed with the blend such as fillers, e.g. sand, gravel and other aggregates normally- employed in such material such as silica and limestone based material. High shearing equipment is not required. The resultant material when used has improved stability under use conditions, has improved antistrip properties and is more resistant to hydrocarbon solvents such as gasoline and the like. Example 1 Solutions containing 5 percent and 10 percent by weight of certain interpolymers in an asphalt were prepared. The asphalt consisted of Marathon 85 to 100 penetration graded material. Three hundred grams of the asphalt were mixed with 30 and 15 grams, respectively, of certain interpolymers at 250°F (121.1°C) until completely dissolved. Viscosity measurements were made on each mixture at 275°F (135°C). Viscosity measurements were made employing ASTM D-2170 standard test conditions. Penetration tests were also run on the samples at 77°F (25°C). These tests were conducted employing ASTM D-5 standard test conditions. The results of these tests are set forth in the following Table I. TABLE I Penetration Viscosity Viscosity Test Interpolymer Polyolefin % wt. Cone. at 77°F (25°C) atl40°F(60°C) at275°F (135°C) No. Composition Melt Flow Index2 in Asphalt (decimillimeter) (poises) (poises) 1 8% acrylic 2600 g/10 min 5 63 1837(183.7Pa-s) 4.6 (0.46Pa-s) acid/92% 10 50 3146(314.6Pa-s) 8.0 (0.8Pas) ethylene 20%acrylic 200 g/10 min 5 35 1362(136.2Pas) 4.1 (0.41Pas) acid/80% 10 33 2133(213.3Pas) 5.0(0.5Pas) ethylene 3% acrylic 11 g/10 min 5 30 4076 (407.6Pas) 8.7 (0.87Pas) acid/97% 10 27 10729 (1072.9Pas) 22.9(2.29Pas) I — i ethylene 1 By weight (%) 2 Melt flow index determined by D-1238-Sch.E ASTM Example 2 An asphalt sample was prepared as in the previous example containing 10 percent by weight of an interpolymer of ethylene and a comonomer set forth in the Table II and having a melt flow index as shown. Biscuit shaped samples were prepared using Hvueem Compaction (described in ASTM test method D-1561). Resilient modulus (Mr) were determined on samples at different temperatures. Resilient modulus was determined on a Mark V resilient modulus apparatus (Retsina Co.). The results of these tests are set forth in the following Table II. TABLE II Melt Test. Interpolymer Index % wt. cone, Temperature No. ComDOsition α/10min in Asphalt (°F α C) MR. osi 1 20% Acrylic Acid 200 10 34°C(1.rc) 2.83X106 80% ethylene 77°F (25°C) 448,400 104°F(40°C) 100,100 2 8%(1)CO 249 10 34°F(1.1°C) 2.27X106 92% ethylene 77°F (25°C) 525,800 104°F(40°C) 139,400 3 7.5 CO 110 10 34°F(1.rC) 2.94x106 92.5 ethylene 77° (25°C) 598,300 104°F(40°C) 168,600 4 3% Acrylic Acid 600 10 34°F(1.1°C) 3.39x106 97% ethylene 77°F (25°C) 690,800 104°F(40°C) 184,500 5 8% Acrylic Acid 700 10 34°F(1.1°C) 2.37x106 77°F (25°C) 627,700 104°F(40°C) 122,500 6 8% Acrylic Acid 2600 10 34°F(1.1°C) 3.31x106 92% ethylene 77°F (25°C) 617,490 104°F(40°C) 175,200 7 20% Acrylic Acid 500 10 34°F(1.rC) 2.33x106 80% ethylene 77°F (25°C) 634,200 104°F(40°C) 99,900 Example 3 In another series of tests, viscosity and penetration tests were performed on various asphalt blends, comparing data with aged and unaged samples. In each sample, a blend of a polymer ( 10% by weight) and asphalt (in Marathon 85-100 penetration graded asphalt cement) was prepared. Part of the sample was then aged in a rolling thin film oven. Viscosity measurements were made at a temperature of 275°F (135°C) and penetration tests at 39°F (4°C). The tests were performed using ASTM-D-2170 for viscosity and ASTM-D-5 for penetration (4°C, load 200 g, time 60 sec). The results of these tests are set forth in the following Table III. TABLE III Melt Test Interpolymer Viscosity Penetration Index No. compositions (centi poise) de imillimeters g/10 min 500 20% Acrylic Acid 553 (5.3.3 Pa.s) 30.25 (aged) 500 80% ethylene 1890 (189Pas) 14.50 700 8% Acrylic Acid 850 (85Pa.s) 24.75 (aged) 700 92% ethylene 2007 (200.7Pa.s) 14.00 2600 8% Acrylic Acid 820(82Pa.s) 26.00 (aged) 2600 92% ethylene 5820(582Pa.s) 13.00 600 3% Acrylic Acid 1740 (174Pa.s) 24.25 (aged) 600 97% ethylene 7030 (703Pa.s) 18.75 2600 19% Acrylic Acid 490 (49Pa.s) 30.75 (aged) 2600 81 % ethylene 8890 (889Pa.s) 14.25 Example 4 In this series of tests the temperature at which 10 percent by weight of a polymer went totally intosolution in an asphalt was determined by visually observing when a homogeneous blend was produced. The compositions and melt flow indexes of the interpolymers in Table IV correspond to the compositions and melt flow indexes of the same test numbers set forth in Table II. TABLE IV Test No. Temperature 1 280° (137.8) 2 280° (137.8) 3 290° (143.3) 4 270° (132.2) 5 275° (135.0) 6 260° (126.7) 7 280° (137.7) in the following examples, a sample was prepared containing asphalt, an aggregate and a certain antistrip additive. The sample was then subjected to a standard "boil test" to ascertain the adhesion of the asphalt to the aggregate. The "boil test" is described in "Texas Boiling Test for Evaluating Moisture Sus¬ ceptibility of Asphalt Mixtures" T. W. Kennedy, F. L. Roberts, J. N. Anagnas, Research Report No. 253-5, January 1984, conducted for Texas State Department of Highways by Center For Transportation Research, Bureau of Engineering Research, The University of Texas at Austin. The boil test consists of boiling in distilled water a sample of the blend and determining, visually, the percentage coverage of the aggregate with asphalt at the conclusion of the test. Greater coverage indicates better performance of the antistrip agent. In a second series of tests, the prepared m samples were subjected to a standard "freeze-thaw" test. In this test, a sample is immersed in distilled water and subjected to 24 hours freeze-thaw conditions until the sample cracks and falls apart. The number of freeze-thaw cycles the sample can withstand before 10 cracking indicates the additive performance. The "freeze-thaw" test is described in Kennedy, T. W. et al. "Texas Freeze-Thaw Pedestal Test for Evaluating Moisture Susceptibility for Asphalt Mixtures", Research Report No. 253-3, Research Project 3-9-79-253 conducted 15 for Texas State Department of Highways and Public Transportation by Center For Transportation Research Bureau of Engineering Research, The University of Texas at Austin, February, 1982. 20 Texas Cosden brand asphalt (AC-20 grade) was used in the tests. This particular asphalt is known to have poor field stripping performance. The amount of asphalt content used was determined on the basis of mm Test Method Tex-204-F. For tests of individual 25 aggregates, the first trial mixture was prepared at the design asphalt content for the mixture in which the aggregate is to be used. Based on the results, subsequent mixtures were prepared at one-half percent 30 increments above or below this trial value. The objective is to coat the aggregate particles with approximately the same asphalt film thickness. There should be very little asphalt left on the mixing bowl after the mixture is removed. In these tests, the 35 amount of asphalt used for all aggregates tested is 5.6 percent for the boil tests and 6.1 percent for the freeze-thaw tests. Example 6 Boil Test A. Mixture Preparation Fifty grams of individual aggregate was heated in an oven at 160°C for 2 hours before mixing. The asphalt cement without antistrip additive was heated at 160°C for at least 8 hours. This will caused some hardening of the asphalt and therefore, simulated asphalts which have been plant-mixed. Then, 3 g (5.6 percent) of asphalt was weighed out into a crucible. The additive to be tested, was added to the asphalt as a weight percent of the asphalt reported in the following Tables. The crucible with asphalt and additive was heated at 160°C with thorough manual mixing for 10 minutes. At this temperature the viscosity of asphalt was low enough to promote even distribution of additive in the asphalt. Heating will also evaluate the thermal stability of the antistripping additive. At the appropriate time, hot aggregate was poured into the asphalt/additive mix and mixed manually on a hot plate as rapidly and thoroughly as possible for 5 minutes. The mixture was then transferred to aluminum foil and allowed to cool at room temperature for at least 2 hours before testing. B. Test Procedures A one-liter beaker was filled with 500 ml of distilled water and heated to boiling. The prepared aggregate-asphalt mixture which was at room temperature was then added to the boiling water. The water was be maintained at a medium boil for 10 minutes while stirring with a glass rod at 3-minute intervals. During and after boiling, the stripped asphalt was skimmed away from the surface of the water with a paper towel to prevent recoating of the aggregate. The mixture was then allowed to cool to room temperature while still in the beaker. After cooling, the water was drained from beaker and the wet mixture was emptied onto a paper towel and allowed to dry. The percentage of asphalt retained on the aggregate was determined by visual observation. To standardize this evaluation, a set of 10 sample mixtures representing a scale of from 0 to 100 percent asphalt retention was prepared. By referring to these standard mixtures, the percentage of asphalt retention can be determined. Higher percentage indicated better adhesion. For each additive, the test was done in duplicate, and the average was used to report the test result. A 70 percent or higher asphalt retention after boil test indicates possible non-stripping field performance. Example 7 Freeze-Thaw Test A. Preparation of Mixture Specimens Test specimen 19.05 ± 0.127 mm (0.75 ± 0.005 in) in height and 41.33 mm (1.627 in) in diameter were prepared, as follows. The aggregate, 46 g for each test specimen, was heated at 160°C for at least 2 hours before mixing with 3 g (6.1 percent) of asphalt in a crucible. The additive was added to the asphalt, in the weight percent of the asphalt as indicated in the following Tables. The crucible with asphalt and additive was heated at 160°C with manual mixing for 5 minutes. The hot aggregate was then poured into the asphalt/additive mix and mixed as thoroughly and rapidly as possible for 5 minutes. The mixture was then heated at 150°C for one-half hour and cooled for over 30 minutes. The compaction of the asphalt mixture into specimens was done in a 1018 cold rolled steel cylindrical mold equipped with a base plate and ram. This mold had a 41.33 mm (1.627 in) inside diameter and was 88.9 mm (3.5 in) in height. The base plate was 41.28 mm (1.625 in) in base diameter and 12.7 mm (0.5 in) in height. The nipple on the center top of the base plate was 6.35 mm (0.25 in) in both diameter and height. The ram was 41.28 mm (1.625 in) in diameter and 114.3 mm (4.5 in) in height. After mixing but before compaction, the mixture was reheated at 150°C for 20 minutes then quickly transfered into the assembled cylinder mold and base plate. The molding ram was inserted and the sample was compacted by applying a constant load of 6,200 ± 50 lbs. on a hydraulic molding press for 7 minutes. The briquet was extracted from the mold and allow to cool. The height of the briquet was 19.05 ± 0.127 mm (0.75 ± 0.005 in). The briquet was cured on a flat surface at room temperature for 2 days. The briquet was then placed on a stress pedestal. This pedestal was made of plexiglass or polycarbonate, has a 10° beveled, 50.8 mm (2.00 in) in diameter, 11.43 mm (0.45 in) in height with a nipple on the top 6.35 mm (0.25 in) in diameter by 3.56 mm (0.14 in) in height. The stress pedestal with briquet was placed in an 8 oz polypropylene wide mouth jar and distilled water was added until it is about one-half inch over the briquet. The jar was capped. B. Test Procedures The jar was placed in a temperature-controlled freezer at -12 ± 3°C for 15 hours. The jar was then transferred to a temperature-controlled oven at 50 ± 2°C for 9 hours. At the end of each complete cycle, the briquet surface was examined for appearance of cracks. If no crack was visible, the specimen was subjected to additional freeze-thaw cycles and examined again until a surface crack appears. The number of freeze-thaw cycles required to crack the briquet was recorded. For each individual additive, 2 specimens were prepared for testing and the average of the results of each test was reported as the test result. If the number of cycles to failure of the two specimens varied by more than 4, additional specimens were prepared and tested until consistent test values were secured. The number of freeze-thaw cycles is related to the effectiveness of the additive. A 25 cycle of freezing and thawing without cracking may indicate non-stripping field performance. Four siliceous aggregates were tested. They were selected from four geographic areas of the United States. The names and location are: Davidson (Georgia); Waco (Texas); Gifford-Hill (Bryan, Texas); and Helms (Nevada). A uniform size was employed. Between 8 and 20 mesh, (U.S. Standard Sieve Series) was used for the boil test and between 20 and 35 mesh (U.S. Standard Sieve Series) was used for the freeze-thaw test. The aggregates were rinsed several times with water and thoroughly dried to a constant weight at 150 ± 3°C prior to use. Tables V, VI and VII report the results of these tests. Table V One Percent By Weight Additive Davidson Gifford Aggregate Hill Test Type B FT B FT Test No. Additive 1 EAA (6.5%AA,9MI) 85 30 85 14 2 EAA (8%AA,700MI) 85 29 85 16 3 EAA (8%AA, 2600MI) 75 29 80 17 * 4 EAA (9%AA, 1.5MI) 95 40 100 21 5 EAA (9%AA,10MI) 90 40 90 19 6 EAA (12-.AA.1.5MI) 95 40 95 19 7 EAA (16%AA.22MI) 100 40 95 19 8 EAA (20%AA, 300MI) 100 40 100 13 9 EAA (20%AA, 1300MI) 95 40 100 17 Table V One Percent By Weight Additive Davidson Gifford Waco Helms Aggregate Hill Test Type FT FT FT FT Test No. Additive 10 EAA (20%AA, 2600MI) 95 40 100 13 100 22 31 11 EAA/Mg Ionomer 85 30 70 15 70 29 (20% AA, 2.5MI) 12 EAA/Mg Ionomer 75 34 80 13 40 21 I (20% AA, 5MI) t- I 13 EAA/Mg Ionomer 85 32 85 18 80 24 (20% AA, 10MI) 14 Allied EAA AC-540 30 16 50 10 40 18 (4.5% AA, WAX) 15 Allied EAA AC-580 60 18 75 11 60 16 (8%AA, WAX) 16 Allied EAA AC-5120 85 15 85 13 85 20 (12.8% AA, WAX) 17 Nucrel=-0910 80 20 85 18 50 25 (9%MAA,10MI) Table V One Percent By Weight Additive Davidson Gifford Waco Helms Aggregate Hill Test Type FT FT FT FT Test No. Additive 18 Surlyn ® -8940 Ionomer 50 14 85 20 40 15 (14% MAA, 2.81MI) 19 Surlyn <B> -9910 Ionomer 30 12 70 17 30 13 ( 14% MAA, 0. 7MI ) I I B - The percentage of asphalt retention on aggregate surface after boil test. Ft The number of freeze-thaw cycles asphalt concrete briquet withstands before cracking. EAA - Ethylene-acrylic acid copolymer. AA - Percent by weight of acrylic acid in the copolymer. MI - Melt flow index . Eaa/Mg Ionomer - % neutralization Allied AC540 - 4.5% AA, WAX The molecular weight of these AC580 -8% AA, WAX materials are too low to use AC5120 - 12. 8% AA, WAX melt index as identifying criteria. They are referred to in the art as "WAXES". Nucrel - (Trademark of duPont Company) Surlyn - (Trademark of duPont Company) Surlyn - (Trademark of duPont Company) means not tested. *"40" figures in FT columns (all comulms) in Tables V and VI means the test was stopped at forty cycles. The specimen was, t- however, still intact at this point . I TABLE VI DIFFERENT ADDITIVE WEIGHT % DAVIDSON GIFFORD - HILL W A C O Test 0.25% 0.5% 1.0% 0.25% 0.5% 1.0% 0.25% 0.5% 1.0% ADDITIVE% No. FT FT FT B FT FT FT FT FT FT F 1 EAA (6.5%AA, 9MI) 80 17 80 22 85 30 60 11 80 12 85 14 80 19 80 25 80 2 2 EAA (8%AA, 700MI) 75 14 80 20 85 29 70 9 80 11 85 16 70 16 75 21 85 2 3 EAA (8%AA, 2600MI) 60 11 60 19 75 29 60 7 60 9 80 17 50 8 60 10 60 1 4 EAA (9%AA, 1.5MI) 80 19 90 27 95 40 80 15 100 21 100 21 75 20 90 26 100 3 5 EAA (9%AA, 10MI) 70 17 80 24 90 40 70 12 80 17 90 19 70 18 85 24 90 3 6 EAA (12%AA, 1.5MI) 80 19 80 28 95 40 75 16 85 19 95 19 70 20 85 28 90 3 7 EAA (16%AA, 22MI) 80 15 90 26 100 40 80 13 90 13 100 13 85 19 90 23 100 2 8 EAA (20%AA, 300MI) 85 15 90 26 100 40 70 13 85 17 95 19 75 19 85 24 95 9 EAA (20%AA, 1300MI) 80 12 85 22 95 40 80 10 90 13 100 17 80 16 90 19 100 2 10 EAA (20%AA, 2600MI) 80 11 80 22 95 40 70 9 80 11 100 13 80 16 90 17 100 2 TABLE VII RESULTS OF FREEZE-THAW TEST (GIFFORD GILL AGGREGATE) AND BOIL TEST (WACO AGGREGATE) USING VARIOUS EAA COPOLYMERS AS ASPHALT ADDITIVES AT DIFFERENT CONCENTRA TIQNS GIFFORD - HILL W A C O Test 0.25% 0.5% 1% 0.25% 0.5% 1% ADDITIVE% No. 1 EAA (6.5%AA, 9MI) 14 - - - 80 95 95 95 90 2 EAA (8%AA, 700MI) 16 - - - - 85 95 loo loo 95 3 EAA (8%AA, 2600MI) 10 13 17 23 27 31 38 60 80 95 100 100 4 EAA (20%AA, 300MI) 8 12 13 13 18 22 29 100 - - I O to I

Claims: CLAIMS 1. A composition which comprises: a bituminous material of from 99 to 50 parts by weight and from 1 to 50 parts by weight of a olefinic polymer selected from the group consisting of homopolymers and interpolymer of an α-olefin and at m least one comonomer selected from the group consisting of α,β-unsaturated carboxylic acid, ionomer of α,β- unsaturated carboxylic acid, vinyl ester of alkanoic acids, and carbon monoxide, wherein said polymer has a melting point between 140°F and 350°F (960°C and 10 176.7°C), a melt flow index ranging from 50 g/10 min to 3000 g/10 min and is dispersible in said bi.tuminous material. 2. The composition of Claim 1, wherein the 15 interpolymer is a copolymer of ethylene and an α,β- unsaturated carboxylic acid. 3. The composition of Claim 1, wherein the olefinic polymer is a homopolymer of ethylene. 20 4. The composition of Claim 1, wherein the interpolymer is a copolymer of an α-olefin and a comonomer selected from the group consisting of at 25 least one of α,β-unsaturated carboxylic acid and carbon monoxide. 5. The composition of Claim 1, wherein the olefinic polymer is an interpolymer of an ethylene and carbon monoxide containing from 1 to 30 percent by weight of carbon monoxide. 6.' The composition of Claim 1, wherein the olefinic polymer is an interpolymer of ethylene and at least one of acrylic acid and methacrylic acid wherein said acid in said polymer ranges from 1 to 30 percent by weight. 7. The composition of Claim 6 wherein the olefinic polymer has a melt index ranging from 100 g/10 min to 3000 g/10 min. 8. The composition of any of Claims 1 to 7 wherein the composition includes a filler. 9. The composition of any of Claims 1 to 7 wherein the olefinic polymer is present in an amount ranging from 1 to 50 percent by weight. 10. A composition comprising a bitumen from about 90 to about 99.9 percent by weight, about 0.1 to about 10 percent by weight of at least one interpolymer of an α-olefin and an α,β-ethylenically unsaturated carboxylic acid or ionomer thereof wherein the interpolymer contains from about 5 to about 30 weight percent of the α,β-ethylenically unsaturated carboxylic acid and about 95 to about 70 weight percent of the α- olefin and wherein the composition is further characterized as being substantially free of α- olefin/ester copolymers. 11. The composition of Claim 10 wherein the interpolymer has a melt flow index ranging from 1.5 g/10 min to about 3000 g/10 min. 12. The composition of Claim 10 wherein the interpolymer contains from about 8 to about 20 percent of acrylic acid, methacrylic acid or mixtures of methacrylic acid and acrylic acid. 13- The composition of Claim 10 including in addition a mineral aggregate. 14. The composition of Claim 10, wherein the interpolymer is present in an amount of about 0.1 to about 5 percent by weight of the composition.

Inventors: CHANG DANE, WOLFE DAVID LEE, CHANG, DANE, WOLFE, DAVID, LEE
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1987
Main classification: C08K3
IPC codes: C08L95