1、Designation: D6703 13D6703 14Standard Test Method forAutomated Heithaus Titrimetry1This standard is issued under the fixed designation D6703; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pa
2、rentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a procedure for quantifying three Heithaus compatibility parameters that quantify the colloidalstability of asphalts and
3、 asphalt cross blends and aged asphalts.1.2 UnitsThe values stated in SI units are to be regarded as standard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilit
4、yof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D8 Terminology Relating to Materials for Roads and PavementsD3279 Test Method forn-Heptane InsolublesD41
5、24 Test Method for Separation of Asphalt into Four FractionsD5546 Test Method for Solubility of Asphalt Binders in Toluene by CentrifugeE169 Practices for General Techniques of Ultraviolet-Visible Quantitative Analysis3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 asphalt bin
6、der, nasphalt which may or may not contain an asphalt modifier (see asphalt modifier).3.1.1.1 DiscussionThis term is often used in the Performance Graded Binder system.3.1.2 asphalt cross-blend, nany mixture of two or more asphalts blended together to form a consistent material.3.1.1 asphaltene pept
7、izability, nthe tendency of asphaltenes to exist as a stable dispersion in a maltene solvent, measured bythe Heithaus parameter pa.3.1.4 asphaltene, ninsoluble fractions of asphalt that are precipitated by use of selected solvents, such as n-heptane.3.1.2 asphalt state of peptization, na measure of
8、the ability of the combination of a maltene solvent and dispersed asphaltenesto form a stable dispersed system.3.1.3 colloidal suspension, nan intimate mixture of two substances, one of which, called the dispersed phase (or colloid), isuniformly distributed in a finely divided state through the seco
9、nd substance, called the dispersion medium (or dispersing medium).3.1.4 compatibility, nthe state of peptization of an asphalt, which is measured quantitatively by the Heithaus parameter P.3.1.5 dispersed phase, none phase of a dispersion consisting of particles or droplets of one substance distribu
10、ted through asecond phase.1 This test method is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.47 onMiscellaneous Asphalt Tests.Current edition approved Dec. 1, 2013June 1, 2014. Published February 2014July 2014. Origina
11、lly approved in 2001. Last previous edition approved in 20072013 asD6703 07.D6703 13. DOI: 10.1520/D6703-13.10.1520/D6703-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, r
12、efer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all
13、changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959
14、. United States13.1.6 dispersing medium, none phase of a dispersion that distributes particles or droplets of another substance, the dispersephase.3.1.7 flocculation, nthe process of aggregation and coalescence into a flocculent mass.3.1.8 Heithaus compatibility parameters, nthree parameters: asphal
15、tene peptizability (pa), maltene peptizing power (po), andasphalt state of peptization (P), measured using Heithaus titration methods.3.1.12 maltene, nsoluble fractions of asphalt that are recovered from an eluate by use of selected solvents, such as n-heptane.3.1.9 maltene peptizing power, nthe abi
16、lity of a maltene solvent to disperse asphaltenes, measured by the Heithaus parameterpo.4. Summary of Test Method4.1 Three 40 mL reaction vials are tared. tared (Fig. 1). Three samples of asphalt of weights 0.400 g, 0.600 g and 0.800 g aretransferred to each of three reaction vials. Toluene (3.000 m
17、L) is added to each reaction vial to dissolve the asphalt constitutingthree solutions which differ by concentration. Each solution is titrated with isooctane (2,2,4-trimethyl pentane) to promote onsetof flocculation of the solution.4.2 Titrations are performed by placing reaction vials separately in
18、 the apparatus illustrated in Fig. 12. Each reaction vial isseparately placed into a 250 mL water-jacketed reaction vessel (vessel.AFig. 1) to provide temperature control of the system. Thesample circulation loop is made by pumping the solution through a short path length quartz flow cell housed in
19、anultraviolet-visible spectrophotometer then back to the reaction vial with high flow rate metering pump. A second reaction vesselis filled with titrant is placed into a second 250 mL water-jacketed reaction vessel.Atitration loop is made by pumping titrant intoFIG. 41 Reaction Vial (30(40 mL) with
20、TFE-fluorocarbon Cover and Temperature ProbeD6703 142the sample reaction vial at a constant flow rate using a low flow rate metering pump. pump, thus a second reaction vessel containingtitrant is placed into a second 250 mL water-jacketed reaction vessel. During a titration the output signal from th
21、easpectrophotometer is recorded using a Datadata acquisition system (computer) to record the change in percent transmittance(%T) of detected radiation at 740 nm passing through the quartz cell plotted versus time, plotted as a function of time t,tduring(Fig. 3 which the titrant.), as the titrated so
22、lution passes through a quartz flow cell.4.3 The spectrophotometer output signal measures turbidity of the sample solution as a titration experiment proceeds to aflocculation onset point, corresponding to the onset of flocculating asphaltene phase separating from the solution. Fig. 23 illustratesa p
23、lot of %T versus t for three test solutions. Values of %T are observed to increase with time up to the flocculation onset point,after which values of %T are observed to decrease. decrease with time. The time required to reach flocculation onset tf multipliedby the titrant flow rate gives the titrant
24、 flocculation volume VT.4.4 Given the weightsThe measured weight of each asphalt sample, Wa, the volume of toluene initially used to dissolve eachsample VS, and the volume of titrant at onset of flocculation VT, values of represent C referred to as the dilution concentrationandthe input data require
25、d FR referred to as the flocculation ratio are calculated as to C = Wa/(VS + VT) and FR = VS/(VS + VT).Values of C plotted along an x-axis versus FR plotted along a y-axis result in a linear regression line (Fig. 3). This line isextrapolated to both axes. The point at which the line intercepts the x
26、-axis is defined as Cmin. The point at which the line interceptsFIG. 12 Automated Titration ApparatusFIG. 23 Onset of Flocculation Peaks Measured at Three Successively Increasing Concentrations (Solvent: Toluene, Titrant: Isooctane)D6703 143the y-axis is defined as FRmax. These two values are used t
27、o calculate the three Heithaus compatibility parameters, designatedcalculate compatibility parameters.pa,po, and P. The parameter pa, the peptizability of asphaltenes, is defined as the quantity (1 FRmax). The parameter po, the peptizing power of maltenes, is defined as the quantity FRmax (1/Cmin) +
28、 1. The parameter P, theoverall compatibility of the system, is defined as po/(1 pa), or (1/Cmin + 1).5. Significance and Use5.1 This test method is intended primarily as a laboratory diagnostic tool for estimating the colloidal stability of bitumen asphalt,asphalt cross blends, aged asphalt, and he
29、avy oil residuum. Historically, bituminous asphalt and heavy oil residua have beenmodeled as colloidal suspensions in which a polar associated asphaltene moiety (the dispersed phase) is suspended in a maltenesolvent moiety (the dispersing medium) (refer to Test Methods D3279, D4124, and D5546 for fu
30、rther definition of asphalt fractionmaterials). The extent to which these two moieties remain in state of peptization is a measure of the compatibility (colloidalstability) of the suspension. Compatibility influences the physical properties of these materials, including rheological properties,for ex
31、ample, phase angle and viscosity. This test method and other similar test methods, along with the classical Heithaus test,measures the overall compatibility of a colloidal system by determining a parameter referred to as the state of peptization, P. Thevalue of P commonly varies between 2.5 to 10 fo
32、r unmodified or neat asphalts. Materials calculated to have low values of P aredesignated incompatible. Materials calculated to have high P values are designated compatible. Values in P are calculated as afunction of two parameters that relate to the peptizability of the asphaltene moiety (the aspha
33、ltene peptizability parameter, pa) andthe solvent power of the maltene moiety (the maltene peptizing power parameter, po). Values of pa and po are calculated asfunctions of the quantities Cmin and FRmax. Values of Cmin and FRmax are determined from experimental variables, the weight ofasphalt (Wa),
34、the volume of solvent (VS) to dissolve the weight of asphalt, and the volume of titrant (VT) added to initiateflocculation.6. Apparatus6.1 UV-visible Spectrophotometer, wavelength scanning range from 200 to 1000 nm, with adjustable aperture or attenuator.6.2 Digital Acquisition System (computer).6.3
35、 Water-Jacketed Reaction Vessel, 250-mL, two.6.4 TFE-fluorocarbon Covers, two.6.4.1 TFE-fluorocarbon Cover No. 1, (see Fig. 41), threaded to hold a 40 mL reaction vial. Three holes, 1.5 mm diameter,concentric to the covers center are tapped to set within the inside diameter of the vial when attached
36、 to the TFE-fluorocarboncover,.cover. One additional hole, 3.0 mm, is tapped off center, positioned just to the outside of where the reaction vial is positionedin the TFE-fluorocarbon cover. This hole allows the temperature probe to be inserted into the water-filled reaction vessel.6.4.2 TFE-fluoroc
37、arbon Cover No. 2, as a lid for the second 200-mL, water-jacketed reaction vessel, containing titrant.Dimensions: thickness, 2.0 mm; diameter, 70 mm. One hole 1.5 mm in diameter tapped through the covers center. This cover isidentical to the cover described in 6.4.1 except for the number of holes, a
38、nd is not threaded.6.5 High Flow Rate Metering PumpFlow rate range from 0.5 to 10.0 mL/min; flow rate consistency, 6 0.1 mL/min; andpiston chamber resistant to damage from solvent contact.FIG. 34 Flocculation Ratio Versus Dilution Concentration for One Stable Asphalt and One Less Stable AsphaltD6703
39、 1446.6 Low Flow Rate Metering PumpFlow rate range from 0.100 to 1.000 mL/min; flow rate consistency,60.002 mL/min; andpiston chamber resistant to damage from solvent contact.6.7 Magnetic Stirring Plates, two.6.8 Refrigerated Water Bath CirculatorTemperature variation, 60.1C; temperature range from
40、0 to 100C.6.9 Quartz Flow Cell, 0.20 mm path length3 with 6.35 mm flanged fittings.6.10 TFE-fluorocarbon Tubing, 0.559 mm inside diameter/1.575 mm outside diameter.6.11 Reaction Vials, 40 mL volume capacity.6.12 “4-hole” TFE-fluorocarbon cover and “1-hole” TFE-fluorocarbon cover.6.13 TFE-fluorocarbo
41、n-Coated Magnetic Stir Bars.6.14 Stopwatch.6.15 Syringe, 5.000 cc, glass, gas-sealed, and resistant to solvents that it will be used to sample.6.16 TFE-fluorocarbon Tube Fittings (4), including standard 6.35 mm flanged fittings for 0.559 mm inside diameter/1.575 mmoutside diameter TFE-fluorocarbon t
42、ubing.6.17 Neoprene Tubing, 13 mm inside diameter.6.18 Tubing Clamps, sized to fit 13 mm inside diameter tubing.6.19 Digital Probe Thermometer, C (calibrated to 60.2C). Probe length, 80-mm, probe diameter, 3.0 mm.6.20 Graduated Cylinders, two. Volumes: 1.000 6 0.001 mL and 10.0 6 0.1 mL.6.21 Argon G
43、as Supply.6.22 Laboratory JacksLaboratory jacks are may be used as stands for the metering pumps previously listed. The sizerequirements of these laboratory jacks will vary depending on the size to the metering metering pumps.6.23 Beakers, two. Volume: 500 mL.6.24 Polypropylene Rinse Bottles, two. V
44、olume: 200 mL.6.25 TFE-fluorocarbon Lined Caps, for 40 mL reaction vials.7. Reagents7.1 Purity of ReagentsHPLC grade chemicals shall be used in all sample preparations and tests. Unless otherwise indicated,it is intended that all reagents conform to the specifications of the Committee on Analytical
45、Reagents of the American ChemicalSociety where such specifications are available.4 Other grades may be used, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening the accuracy of the determination.7.2 Isooctane (2,2,4-trimethylpentane), H
46、PLC grade.7.3 Toluene, HPLC grade.7.4 Toluene, reagent grade.8. Assembly8.1 Installation Requirements:8.1.1 It is recommended that the following assembly be conducted in a fume hood. The fume hood should be of sufficient sizeto accommodate all pieces of the apparatus and supplies needed to perform t
47、he test method.8.1.2 The fume hood should be equipped with a pump or house vacuum line for the assembly of a vacuum trap, used duringthe procedural cleanup step (see 10.2.8).8.2 Assembly (Fig. 12):8.2.1 Circulation Loop AssemblyA sample (circulation loop) is assembled using a high flow rate metering
48、 pump plumbedbetween a short path length flow cell and a TFE-fluorocarbon cover (fitted to a 40 mLreaction vial/200 mLwater-jacketed reactionvessel assembly) using 0.559 mm inside diameter/1.575-mm outside diameter TFE-fluorocarbon tubing fitted with standard 6.2mm flange fittings adaptable to 0.559
49、 mm inside diameter/1.575 mm outside diameter tubing.3 The sole source of supply of the apparatus known to the committee at this time is Starna Cells, Inc. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee,1 which you mayattend.4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not list
