Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments (2017)

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84 A T T A C H M E N T 2 This attachment describes four proposed test methods for determining the asphalt emulsion and binder residue properties that are related to surface treatment performance. • Proposed Standard Method of Test for Determining Storage Stability of Emulsified Asphalts: Resistance to Physical Separation and Change in Rheological Properties • Proposed Standard Method of Test for Determining the Viscosity of Spray Grade Emulsified Asphalts Using the Three-Step Shear Test • Proposed Standard Method of Test for Determining Dynamic Shear Modulus of Emulsion Residues at Critical Phase Angle Values Using the Dynamic Shear Rheometer (DSR) • Proposed Revisions to ASTM D 3121 Standard Test Method for Tack of Pressure-Sensitive Adhesives by Rolling Ball These proposed test methods are the suggestions of the NCHRP Project 9-50 research team. These test methods have not been approved by the NCHRP or any AASHTO committee nor have they been formally accepted for AASHTO specifications. Proposed Test Methods

Proposed Test Methods 85 Proposed Standard Method of Test for Determining Storage Stability of Emulsified Asphalts: Resistance to Physical Separation and Change in Rheological Properties AASHTO Designation: TP-XX 1. SCOPE 1.1 This test method covers the procedure for evaluating the ability of emulsified asphalt to remain homogenous and resist physical separation and or change in rheological properties during storage. It is applicable to all emulsified asphalts used for road construction applications. 1.2 The test procedure for evaluating resistance to physical separation (settlement or creaming) is similar to the test procedure specified in ASTM D6930-10 Standard Test Method for Settlement and Storage Stability of Emulsified Asphalts. The procedure for evaluating change in rheological properties is based on assessing viscosity, measured using T 316, Standard Method of Test for Viscosity Determination of Asphalt Binder Using Rotational Viscometer. 1.3 Stability against settlement or creaming (physical separation) is determined by comparing the viscosity of emulsified asphalt samples taken from the top and bottom of a conditioned sample. Stability against change in rheological properties is determined by measuring and comparing the viscosity of an emulsified asphalt sample before and after conditioning. The test method applies to all fresh asphalt emulsions. The values stated in SI units are to be regarded as the standard. 1.4 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1 AASHTO Standards: T 40, Standard Method of Test for Sampling Bituminous Materials M 140, Standard Specification for Emulsified Asphalt M 316, Standard Specification for Polymer Modified Cationic Emulsion M 208, Standard Specification for Cationic Emulsified Asphalt T 316, Standard Method of Test for Viscosity Determination of Asphalt Binder Using Rotational Viscometer E 145, Gravity-Convection and Forced-Ventilation Ovens

86 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 3. TERMINOLOGY 3.1 Definitions 3.1.1 Viscosity: apparent viscosity, η—the ratio of shear stress to shear rate for a Newtonian or non-Newtonian liquid. 3.1.2 Separation Ratio: ratio of the residual asphalt content of the top sample divided by the residual asphalt content of the sample taken from the bottom of the cylinder. 3.1.3 Degradation Ratio: ratio of the viscosity of the emulsified asphalt before and after conditioning. 4. SUMMARY OF METHOD 4.1 Storage stability is evaluated based on the resistance to both change in physical properties and rheological properties after a prescribed conditioning time. 4.2 Stability against physical separation or homogeneity is evaluated by comparing the ratios of viscosity measured from samples taken from the top and bottom of a cylinder placed in undisturbed simulated storage for a specified time period. The result is expressed by a separation ratio (Rs), calculated as the ratio of the viscosities of the two samples. 4.3 Stability against change in rheological properties is evaluated by measuring the viscosity of the emulsified asphalt before and after conditioning. The result is expressed by a degradation ratio (Rd), determined as the ratio of the viscosity before conditioning to the viscosity after conditioning. 2.2 ASTM Standards: D140, Practice for Sampling Bituminous Materials D977, Specification for Emulsified Asphalt D6930, Standard Test Method for Settlement and Storage Stability of Emulsified Asphalt D4402M-13, Standard Test Method for Viscosity Determination of Asphalt at Elevated Temperatures Using a Rotational Viscometer D2397, Specification for Cationic Emulsified Asphalt E77, Inspection and Verification of Thermometers E220, Test Method for Calibration of Thermocouples by Comparison Techniques E145, Gravity-Convection and Forced-Ventilation Ovens

Proposed Test Methods 87 5. SIGNIFICANCE AND USE 5.1 This test method is useful for determining, in a comparatively short time, the storage stability of emulsified asphalt. It is a measure of the permanence of the dispersion and rheological properties as related to time, but it is not to be construed to have significance as a measure of other stability aspects involved in its use. 6. APPARATUS 6.1 Apparatus for Sample Conditioning and Sampling 6.1.1 Cylinder: 500-mL glass cylinder, with pressed or molded glass base and cork, rubber, or glass stopper, having an outside diameter of 50 ± 5 mm. The use of a cylinder containing side arm glass tubes to permit the siphoning of the material rather than pipetting may also be used as an acceptable alternative method. 6.1.2 Glass Pipette: A 50-mL siphon glass-tube pipet of optional form. The tip of the pipette shall be cut off to minimize incidences of blockage that may occur as a result of a small pipette tip. 6.1.3 Plastic Can: At least six 9.5-cm diameter and 3.7-cm high stainless steel cans. 6.1.4 Scale: Capable of weighing 1000 g to 0.1 g. 6.1.5 Beakers: Two 1000-mL glass or metal beakers. 6.1.6 Stir Rods: Glass or stainless steel with rounded ends. 6.2 Conditioning Oven 6.2.1 Forced Draft Oven: Capable of maintaining temperatures from 20°C above ambient temperature to at least 160°C. Within this range the oven must meet temperature control requirements for a Type IIB forced draft oven, as defined in ASTM E145. Use as many ovens as necessary to accommodate the required heating conditions for emulsified asphalt needed for sample conditioning. 6.3 Rotational Viscometer 6.3.1 Viscometer: A rotational viscometer conforming to the requirements specified in ASTM D4402M-13. 6.3.2 Apparatus Measuring Geometry: Of various shapes and sizes for measurement of various viscosities of asphalt and emulsified asphalt.

88 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 6.3.3 Temperature: Controlled thermal chamber heater for maintaining the sample of asphalt at the test temperature. 6.3.4 Sample Chambers: Disposable sample chambers. 6.3.5 Temperature Controller: Capable of maintaining the specimen temperatures to ±1.0°C (±2.0°F) for test temperatures between 20° and 260°C. 6.3.6 Calibration Device: In accordance with ASTM E 220 for calibrating the temperature controller. 7. SAFETY PRECAUTIONS 7.1 Observe standard laboratory safety precautions when preparing and testing emulsified binders. 8. PREPARATION OF APPARATUS 8.1 The cylinder for conditioning the emulsion sample shall be cleaned properly and dried prior to use. 8.2 The rotational viscometer and thermal chamber heater shall be leveled and prepared as recommended by the instrument manufacturer. 9. CALIBRATION OF THE ROTATIONAL VISCOMETER 9.1 The rotational viscometer shall be calibrated in accordance with ASTM D4402M-13. 10. STORAGE CONDITIONS 10.1 In general, emulsified asphalt should be evaluated under storage conditions (with appropriate tolerance) that test its thermal stability and, if applicable, its sensitivity to other factors that may be experienced in the field and may contribute to destabilization, such as shaking. The storage conditions and the lengths of studies chosen should be sufficient to cover storage, shipment, and subsequent use. 10.2 NOTE 1—Exercise caution to avoid sample overheating and to avoid the ignition of samples with low flash points. A shaker table may be used to test vibration stability when the emulsified asphalt is to be subjected to vibration. This suggestion may be especially applicable to packaged emulsified asphalt that is shipped and/or transported to remote areas and is likely to be subjected to shaking and vibration during transportation.

Proposed Test Methods 89 11. TESTING PROCEDURE 11.1 Test Procedure for Physical Stability 11.1.1 Bring the emulsified asphalt to the anticipated storage temperature. Mix the emulsified asphalt thoroughly and pour about 100 mL in a plastic container. This sample will be evaluated for viscosity before conditioning as described under Section 11.2. 11.1.2 Carefully pour a representative sample of 500 mL each in two glass cylinders and stopper the cylinders. Place the two cylinders in a forced draft oven already at a pre-set specified conditioning temperature. The minimum recommended temperature for rapid-setting emulsions (emulsified asphalt used in chip seals) is 60°C, and that for slow-setting emulsions (emulsions used in slurry seals and microsurfacing applications) is 25°C. 11.1.3 Allow the samples to stand undisturbed for 24 hours for short-term storage stability or five days for long-term storage stability. 11.1.4 After the samples have stood for this period, take three clean (never used) plastic containers (9.5 cm diameter and 3.7 cm high). With a permanent marker, mark the three containers as Top, Bottom, and Mixed, respectively. 11.1.5 From one of the two cylinders, carefully remove approximately 50 ± 5 mL of emulsified asphalt from the top of the cylinder using a pipet or siphon without disturbing the remainder of the sample. Place the sample in the plastic container marked Top. 11.1.6 After removing the top portion, carefully siphon off the next 390 mL (approximately) from the cylinder, taking care not to disturb the emulsion at the bottom of the cylinder. Thoroughly stir the emulsified asphalt remaining in the cylinder. Weigh 50 ± 5 mL into the plastic container marked Bottom. 11.1.7 For the remaining second cylinder, carefully and thoroughly mix the emulsified asphalt by gently shaking and inverting the cylinder and/or by stirring the emulsion with a glass rod that can reach the bottom of the cylinder. Record any obvious evidence of broken emulsion at the bottom of the cylinder or in the emulsion. After mixing, place a sample of about 100 mL in the plastic container marked Mixed. 11.1.8 Test the samples for viscosity using the procedure described under Section 11.2. 11.2 Testing for Emulsion Viscosity 11.2.1 Follow the manufacturer’s instructions for the operation of the instrument.

90 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 11.2.2 Allow the instrument electronics to warm up for at least five minutes before conducting any calibrations or analyses. 11.2.3 Set the temperature controller to the desired test temperature, taking into account any offset determined under Section 9. 11.2.4 Select an apparatus-measuring geometry that will develop a resisting torque between 10% and 98% of the instrument capacity at the selected speed. Generally, measurements will be more accurate at higher torque readings. 11.2.5 Preferably, preheat the sample chamber and the selected apparatus-measuring geometry until temperature equilibrium has been obtained for at least 10 minutes. 11.2.6 Add the volume of sample specified by the manufacturer for the apparatus- measuring geometry to be used to the sample chamber. A convenient way to measure the volume is to weigh out the amount calculated from approximate density data for the sample and then return the sample chamber to the temperature-controlled chamber heater. Thoroughly stir the filled asphalts to obtain a representative sample before weighing. NOTE 2—Exercise caution to avoid premature breaking of the emulsified asphalt sample by overheating and to avoid the ignition of samples with low flash points. 11.2.7 Insert the selected preheated apparatus-measuring geometry into the liquid in the chamber and couple it to the viscometer, following the manufacturer’s instructions for proper alignment. 11.2.8 Allow the emulsified asphalt to equilibrate at the desired test temperature for a minimum of five minutes before taking measurements. 11.2.9 Start the motor rotation of the viscometer at a speed of 5 rotations per minute (RPM) or at a shear rate of 4.65 s-1. Maintain this speed/shear rate for an additional 15 minutes. The temperature should not deviate more than ±1.0°C (±2.0°F) during the testing period. 11.2.10 Measure either the viscosity or the torque at 10-second intervals for a total of 15 minutes. The instrument may perform this measurement automatically. 11.2.11 If the instrument does not read out directly in viscosity units, multiply the torque readings by the appropriate factor to obtain the viscosity values. 11.2.12 Calculate the results as the arithmetic average of the six readings taken at the 15th minute, rounded to three significant figures. 11.2.13 If the rotational viscometer has a digital output that displays viscosity in centipoise (cP), multiply by 0.001 to obtain the viscosity in pascal seconds

Proposed Test Methods 91 (Pa·s). For instruments that offer automation, the results of the 15th minute integration shall be acceptable. 11.2.14 Repeat steps 11.2.4 through 11.2.13 for each replicate and test temperature required. 11.2.15 If the torque reading is below 10% of the instrument capacity at the highest test temperature, repeat steps 11.2.4 through 11.2.10 using a larger diameter geometry and the appropriate volume of sample. 11.2.16 At least three replicate tests should be performed on each sample. 12. CALCULATIONS AND REPORT 12.1 Calculate the storage stability indices of the emulsified asphalt as follows: (Eq 1) (Eq 2) where Rs = separation ratio Rd = degradation ratio η = emulsified asphalt viscosity (Pa·s) NOTE 3—Emulsified asphalt with a separation ratio greater than unity is considered susceptible to creaming whereas emulsified asphalt with a separation ratio less than unity is considered susceptible to settlement. Emulsified asphalt with a separation ratio close to unity is considered stable against physical separation. NOTE 4—Emulsified asphalt with a degradation ratio greater or less than unity is considered susceptible to rheological instability and hence prone to changes in rheological properties during storage. 13. REPORT 13.1 Sample Preparation and Test Conditions 13.1.1 Emulsified asphalt type name 13.1.2 Conditioning temperature (°C) and conditioning time (hr) Rs = ηtop sample ηbottom sample Rd = ηbefore conditioning ηafter conditioning

92 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 13.1.3 Viscosity test temperature to the nearest °C 13.1.4 Rotational viscometer: Apparatus-measuring geometry type and size 13.2 Test Results 13.2.1 Torque in mNm or percent of instrument capacity and speed in sec-1 or r/min 13.2.2 Viscosity results in pascal seconds (Pa·s), millipascal seconds (mPa·s), or centipoise (cP) for top, bottom, mixed, and unconditioned samples 13.2.3 Separation ratio (Sr), degradation ratio (Dr) 13.2.4 Arithmetic mean and standard deviation of at least three individual measurements to the nearest 1% 13.2.5 Stability phenomenon: record if chunks or strings formed in the emulsion during storage. 14. PRECISION AND BIAS 14.1 Precision and bias have yet to be established for this test method.

Proposed Test Methods 93 Proposed Standard Method of Test for Determining the Viscosity of Spray Grade Emulsified Asphalts Using the Three-Step Shear Test AASHTO Designation: TP-XX 1. SCOPE 1.1 This test method uses a rotational viscometer and a temperature-controlled thermal chamber to measure the viscosity of emulsified asphalt. Testing is carried out at varying shear rates to simulate the conditions of handling and applying emulsion in spray seals and chip seals; these conditions include circulation, spraying, and drainout. The values stated in SI units are to be regarded as the standard. 1.2 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.2 ASTM Standards: D88, Test Method for Saybolt Viscosity D244, Test Methods and Practices for Emulsified Asphalts D977, Specification for Emulsified Asphalt D2397, Specification for Cationic Emulsified Asphalt D140, Practice for Sampling Bituminous Materials D7496, Test Method for Viscosity of Emulsified Asphalt by Saybolt Furol Viscometer D4402M-13, Standard Test Method for Viscosity Determination of Asphalt at Elevated Temperatures Using a Rotational Viscometer 2.1 AASHTO Standards: T 40, Standard Method of Test for Sampling Bituminous Materials M 140, Standard Specification for Emulsified Asphalt M 316, Standard Specification for Polymer Modified Cationic Emulsion M 208, Standard Specification for Cationic Emulsified Asphalt T 316, Standard Method of Test for Viscosity Determination of Asphalt Binder Using Rotational Viscometer E 145, Gravity-Convection and Forced-Ventilation Ovens

94 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 3. TERMINOLOGY 3.1 Definitions 3.1.1 Viscosity: apparent viscosity, η—the ratio of shear stress to shear rate for a Newtonian or non-Newtonian liquid. 4. SUMMARY OF METHOD A rotational viscometer is used to measure the viscosity of emulsified asphalt at different shear rates at a specified temperature. A sample of emulsified asphalt is poured into a sample holder and inserted into a thermostatically controlled sample holder. The rotating spindle is lowered into the sample and the assembly is allowed to equilibrate to the test temperature. The torque of the spindle rotating in the emulsified asphalt sample at a constant speed (rotation per minute, or RPM) is measured. Testing is carried out by varying the shear rate in three steps. The sample is tested at a shear rate of 4.65 s-1 (5 RPM) for 15 minutes, and then the shear rate is changed to 142 s-1(150 RPM) for 5 minutes, and then back to a shear rate of 4.65 s-1 for 5 minutes. The torque and rotational speed are used to determine the viscosity of the asphalt in pascal seconds, millipascal seconds, or centipoise. The results are used to determine sprayability (the ease with which an emulsified asphalt can be sprayed) and resistance to drainout. 5. SIGNIFICANCE AND USE 5.1 The viscosity of emulsified asphalt characterizes its flow properties and affects the ease with which emulsified asphalt can be handled and used. Emulsified asphalt used for spray applications should have low viscosity values so that it can be applied uniformly through the spray bar of the distributor, but at the same time should be viscous enough not to drain from the crown or grade of the road. 5.2 The viscosity of emulsified asphalt is affected by shear and time. Therefore, this test method allows the emulsified asphalt to be evaluated in three steps with different shear rates to simulate handling and application conditions. 6. SAMPLE CONDITIONING FOR TESTING 6.1 All emulsified asphalts shall be stirred properly to achieve homogeneity before testing. 6.2 Emulsified asphalt for spray applications shall be heated to the field spray temperature in its original sample container in a forced draft oven. In cases where the spray temperature is unknown, a temperature of 60 C ± 3 C shall be used. E1, Specification for ASTM Liquid-in-Glass Thermometers E11, Specification for Woven Wire Test Sieve Cloth and Test Sieves E77, Inspection and Verification of Thermometers E220, Test Method for Calibration of Thermocouples by Comparison Techniques

Proposed Test Methods 95 6.3 The container should be vented to relieve pressure. After the sample reaches the specified temperature, stir the sample to achieve homogeneity. 7. APPARATUS 7.1 Viscometer: A rotational viscometer conforming to the requirements specified in ASTM D4402M-13. 7.2 Rotating Spindle: Of various shapes and sizes, for measurement of various viscosities of asphalt and emulsified asphalt. 7.3 Temperature: Controlled thermal chamber heater, for maintaining the sample of asphalt at the test temperature. 7.4 Sample Chambers: Disposable sample chambers. 7.5 Temperature Controller: Capable of maintaining the specimen temperatures to ±1.0°C (±2.0°F) for test temperatures between 20°C and 260°C. 7.6 Calibration Device: In accordance with ASTM E220 for calibrating the temperature controller. 7.7 Thermometers: ASTM No. 17C or 17F for tests at 25°C and ASTM No. 19C or 19F for tests at 60°C, conforming to the requirements of ASTM E 1 or any other thermometric device of equal accuracy. 7.8 Forced Draft Oven: Capable of maintaining temperatures from 20°C above ambient temperature to at least 160°C. Within this range the oven must meet temperature control requirements for a Type IIB forced draft oven as defined in ASTM E145. Use as many ovens as necessary to accommodate the required heating conditions for emulsified asphalt needed for sample conditioning. 8. SAFETY PRECAUTIONS 8.1 Observe standard laboratory safety precautions when preparing and testing emulsified binders. 8.1.1 Warning: Mercury has been designated by the Environmental Protection Agency (EPA) and many state agencies as a hazardous material that can cause damage to the central nervous system, kidneys, and liver. Mercury, or its vapor, may be hazardous to human health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product material safety data sheet for details and the EPA’s website (www.epa.gov/mercury/faq.htm) for additional information. Users should be aware that selling mercury or mercury-containing products (or both) may be prohibited by state law. 9. PREPARATION OF APPARATUS 9.1 The rotational viscometer and thermal chamber heater shall be leveled and prepared as recommended by the instrument manufacturer.

96 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 10. CALIBRATION OF THE ROTATIONAL VISCOMETER 10.1 The rotational viscometer shall be calibrated in accordance with ASTM D4402M-13. 11. TESTING PROCEDURE 11.1 Follow the manufacturer’s instructions for the operation of the rotational viscometer. 11.2 Allow the rotational viscometer’s electronics to warm up for at least 10 minutes before conducting any calibrations or analyses. 11.3 Set the temperature controller to the desired test temperature, taking into account any offset determined under Section 7.0. 11.4 Select a rotating spindle that will develop a resisting torque between 10% and 98% of the instrument capacity at the selected speed. Generally, measurements will be more accurate at higher torque readings. 11.5 Preheat the temperature controller heater and the rotating spindle to the desired test temperature. Allow the assembly to equilibrate at the test temperature for at least 10 minutes. 11.6 Add the volume of sample specified by the manufacturer to be used for the rotating spindle to the sample chamber. A convenient way to measure the volume is to weigh out the amount calculated from approximate density data for the sample. Thoroughly stir the emulsified asphalt to obtain a representative sample before weighing. 11.7 NOTE 1—Only one sample should be poured at a time to avoid exposing the emulsified asphalt to air and to avoid premature breaking or drying out of the emulsion. 11.8 Insert the selected preheated rotating spindle into the liquid in the chamber and couple it to the viscometer, following the manufacturer’s instructions for proper alignment. 11.9 Allow the emulsified asphalt to equilibrate at the test temperature for at least 5 minutes before taking the measurement. 11.10 Apply the 3-step shear test to the emulsions as follows: Step 1: Start the motor rotation of the viscometer at a speed of 5 rotations per min (RPM) or at a shear rate of 4.65 s-1 and maintain this speed/shear rate for 15 minutes. Step 2: Change the speed to 150 RPM or shear rate of 141.83 s-1 and allow the test to run at this speed for 5 minutes. Step 3: Change the speed to 5 RPM again and allow the test to run for another 5 minutes. No rest period should be allowed between the speed changes. The total testing time shall be 25 minutes. The temperature should not deviate more than ±1.0°C (±2.0°F) during the testing period. 11.11 Measure either the viscosity or the torque at 5-second intervals for the duration of the test. The instrument may perform this measurement automatically. If the instrument does not read out directly in viscosity units, multiply the torque readings by the appropriate factor to obtain the viscosity values. An example of the 3-step test is shown in Figure 11.1.

Proposed Test Methods 97 Figure 11.1. Typical results from the 3-step shear test using the rotational viscometer. 11.12 Repeat steps 11.6 through 11.10 for each replicate and test temperature required. 11.13 If the torque reading is below 10% of the instrument capacity at the highest test temperature, repeat Steps 11.6 through 11.10 with a larger diameter geometry and the appropriate volume of sample. 11.14 Test at least three replicates for each emulsion type. 12. CALCULATIONS AND REPORT 12.1 Calculate the results of viscosity for sprayability and drainout as follows: Sprayability = average η of all the data points collected during the last one minute of Step 2 at g =140 s-1 Drainout = average η of all the data points collected during the last one minute of Step 3 at g = 4.65 s (Eq. 1) (Eq. 2)-1 where Sprayability = viscosity at high shear rate Drainout = viscosity at low shear rate after subjected to a high shear rate η = emulsified asphalt viscosity (cP) g = shear rate (s-1) 13. REPORT 13.1 Sample Preparation and Test Conditions

98 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 13.1.1 Emulsified asphalt type name 13.1.2 Viscosity test temperature to the nearest °C 13.1.3 Rotational viscometer: Rotating spindle type and size 13.2 Test Results 13.2.1 Torque in mNm or percent of instrument capacity and speed in sec-1 or r/min 13.2.2 Viscosity results in pascal seconds (Pa·s), millipascal seconds (mPa·s), or centipoise (cP) for all replicates 13.2.3 Sprayability and drainout results 13.2.4 Arithmetic mean and standard deviation of at least three individual measurements to the nearest 1% 14. PRECISION AND BIAS 14.1 Precision and bias have yet to be established for this test method.

Proposed Test Methods 99 Proposed Standard Method of Test for Determining Dynamic Shear Modulus of Emulsion Residues at Critical Phase Angle Values Using the Dynamic Shear Rheometer (DSR) AASHTO Designation: TP-XX 1. SCOPE 1.1 This test method covers the procedure for determining the dynamic shear modulus of emulsion residue at critical phase angle values by conducting DSR frequency sweep tests at intermediate temperatures. 1.2 The test procedure is used to evaluate the thermal cracking resistance of microsurfacing emulsion residue and raveling resistance of chip seal emulsion residue. 1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1 AASHTO Standards: M 315, Standard Test Method for Determining the Rheological Properties of Asphalt Binder Using a Dynamic Shear Rheometer M 320, Standard Specification for Performance-Graded Asphalt Binder PP 72, Residue Recovery Using Low Temperature Evaporative Techniques 2.2 ASTM Standards: D 7175, Standard Test Method for Determining the Rheological Properties of Asphalt Binder Using a Dynamic Shear Rheometer D 7497, Residue Recovery Using Low Temperature Evaporative Techniques 3. TERMINOLOGY 3.1 Definitions: 3.1.1 Emulsion residue – The asphalt recovered from emulsion after evaporating water completely from emulsion either environmentally or by heating. 3.1.2 Dynamic shear modulus (G*) – The ratio of peak absolute shear stress (τ) and peak absolute shear strain (γ).

100 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 3.1.3 Phase angle ( ) – The phase difference in radians or degrees between applied strain and resultant stress in strain controlled test or the phase difference in radian or degree between applied stress and resultant strain in stress controlled test. 3.1.4 Parallel plate geometry – The plates that are used in DSR to apply shear force on test specimens in torsion mode. The contact surfaces of parallel plates are parallel to each other. 3.1.5 Calibration – This is a procedure to check the accuracy and precision of machines and apply correction where needed according to specified standards. 3.1.6 Thermal equilibrium – This defines the stabilized target temperature in test specimen. 3.1.7 Frequency sweep test – This is a test procedure where the parallel plate oscillates within a specific strain (strain controlled test) or specific stress (stress controlled test) within a fixed frequency range at one or more temperatures. 3.1.8 Trimming Gap – The gap between parallel plates when the excess residue is removed by a trimming tool. 3.1.9 Geometry Gap – The gap between parallel plates when the DSR test is conducted on specimens. 4. SUMMARY OF METHOD 4.1 Test specimens with 2.0 mm height are formed between 8 mm diameter parallel plates. During testing, specimens are subjected to torsional oscillation at pre-selected frequencies and rotational deformation amplitudes (strain amplitudes). 4.2 The test is maintained at the test temperature to within ±0.1°C by positive heating and cooling of the upper and lower plates or by enclosing the upper and lower plates in a thermally controlled environment or test chamber. 4.3 The dynamic shear modulus (|G*|) and phase angle (δ δ ) are calculated automatically as part of the operation of the DSR using proprietary computer software supplied by the equipment manufacturer. 5. SIGNIFICANCE AND USE 5.1 This test method is a significant benefit to determine low temperature creep properties of emulsion residue in several ways: (1) the test requires <0.25gm residue for one specimen which is 60 times less than the required residue to prepare one beam for BBR testing under AASHTO T 313, (2) the intermediate frequency sweep test temperatures are easily achievable in the DSR compared to low test temperatures utilized in AASHTO T 313, and (3) DSR testing at low temperatures corresponding to AASHTO T 313 require application of torques beyond the capacity of typical DSRs. 5.2 Master curves of G* and δ at selected temperatures can be developed by implementing time-temperature superposition. The master curves can be used to calculate the low temperature performance related criteria proposed in AASHTO M 320.

Proposed Test Methods 101 6. APPARATUS 6.1 The DSR, environmental chamber control, and data acquisition system shall meet the requirements of T 315. Test plates shall be 8 mm ±0.01 mm in diameter and stainless steel or aluminum with a smooth ground surface. In addition, the rheometer shall be equipped with a normal force sensor. 7. SAFETY PRECAUTIONS 7.1 Observe standard laboratory safety precautions when preparing and testing emulsified binders. 8. PREPARATION OF APPARATUS 8.1 Prepare the apparatus for testing in accordance with the manufacturer’s recommendations. Specific requirements will vary for different DSR models and manufacturers. 8.2 Inspect the surfaces of the test plates and discard any plates with jigged or rounded edges or deep scratches. Clean any asphalt binder residue from the plates using an organic solvent such as oil, mineral spirits, a citrus-based solvent, or toluene. Remove any remaining solvent residue by wiping the surface of the plates with a cotton swab or a soft cloth dampened with acetone. If necessary, use a dry cotton swab or soft cloth to ensure that no moisture condenses on the plates. 8.3 Mount the cleaned and inspected test plates on the test fixtures and tighten firmly. 9. CALIBRATION OF THE DYNAMIC SHEAR RHEOMETER 9.1 The DSR shall be calibrated in accordance with AASHTO T 315. 10. PREPARING TEST SAMPLES 10.1 Recover emulsion residue in accordance with Method B of AASHTO PP 72. 10.2 Separate 0.25 g residue by hand, spatula, or other metal tool. Then, place this 0.25 g of residue between two fingers and squeeze firmly to make a small ball. Place the residue on an 8-mm diameter silicon mold and press with finger to flatten. 10.3 The trimming, specimen fabrication, and conditioning should be performed according to AASHTO T 315. 11. TESTING PROCEDURE 11.1 Bring the specimen test temperature ±0.1°C and wait for 15 minutes at test temperature for thermal equilibrium. 11.2 After 15 minutes of conditioning time, perform a logarithmic frequency sweep test from 0.1 to 100 rad/sec with 10 loading frequencies per decade maintaining 1% strain amplitude at two different temperatures: 15°C and 5°C, starting from 15°C followed by

102 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments 5°C. Specimens should be conditioned for 15 minutes at the test temperature prior to frequency sweep loading. 11.3 The data acquisition system will record |G*| and δ automatically at each loading frequency. 11.4 When the temperature-frequency sweep test is complete, increase the temperature to 60°C or higher so that the residue becomes soft. Use mineral oil, citrus based solvents, mineral spirits, toluene, or similar solvents to clean the plates. Clean cloth, paper towels, cotton swabs or other suitable material can be used to wipe off the plates. Finally, organic solvent such as heptane, acetone, or ethyl alcohol can be used to remove the solvent residue from the surface of plates. 12. ANALYSIS OF TEST RESULTS 12.1 Apply time-temperature superposition to shift the |G*| and data acquired at 5°C to a reference temperature of 15°C. To do so, the actual loading frequencies ( ) at 5°C are converted to reduced frequency ( R) using a time-temperature shift factor (aT) in accordance to Equation 12.1 such that the relationships between |G*| and R and and R obtained from both 15°C and 5°C align to form a single curve. R Ta (12.1) 12.1.1 To determine aT, first identify the portion of the |G*| data from 15°C and 5°C with overlapping G* values as shown graphically in Figure 12.1. These data will be used for determining the aT. Figure 12.1. Depiction of identification of data for use in determining the time-temperature shift factor. d w w w w w w d

Proposed Test Methods 103 G ( ) ( )5log( * * log( log(log( )) ) )oCi, 15oCi–, 15oCi–,15oCi+,G G )*log( ) – 15oCi+,G *log( 15oCi–,G –– )(gol 1, 5oCi–+ w ww 51, )(gol o Ci =w 12.1.2 For each identified data point, i, at 5°C, determine the time-temperature shift factor (aT,i) required to align the corresponding G* value (G*5°C,i) with the 15°C G* versus curve. To do so, first determine the ω value at 15°C ( i,15°C) with the equivalent G* value as G*5°C,i via interpolation between the 15°C data point with the G* value closest to but less than G*5°C,i (G*i-,15°C) and the 15°C data point with the G* value closest to but greater than G*5°C,i (G*i+,15°C) using Equation 12.2 (illustrated schematically in Figure 12.2). (12.2) Once each i,15°C is determined, calculate corresponding aT,i values using Equation 12.3. The aT value for 5°C is then calculated as the average of all aT,i values. Figure 12.2. Depiction of the determination of the time-temperature shift factor. w , ,15 ,5log( ) log( ) log( )o oT i i C i Ca (12.3) 12.1.3 Shift the 5°C to 15°C by converting frequency to reduced frequency using the computed aT values in Equation 12.1. (Note that the time-temperature shift factor for 15°C is 1.) 12.2 Fit the master curve by Christensen-Anderson-Marasteanu (CAM) model (Equations 12.4 and 12.5) (Marasteanu and Anderson 1999). 1 w v v c g R (12.4) ww w w w w G

104 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments n ) ) l ( )d d d d d d d d w w w w w w w w w w w G e 90 1 v R c w (12.5) where *G = Dynamic shear modulus, gG = Glassy dynamic shear modulus, equal to 109 Pa R = Reduced frequency, c = Crossover frequency, equal to the reduced frequency corresponding to a phase angle value of 45°, and v , w = Shape parameters. 12.2.1 To determine c, a line is fit to log( R) versus log(tan( )) using the form given in Equation 12.6. log( og(tan( ))R a b (12.6) where a and b are best fit parameters. The crossover frequency is then calculated using Equation 12.7. 10ac (12.7) 12.2.2 To determine v, a line is fit to log(log(Gg /G*) versus log(tan( )) using the form given in Equation 12.8. log log log(ta* *) gG c dG (12.8) where c and d are best fit parameters. The parameter v is then calculated using Equation 12.9. log(2) 10b v (12.9) 12.2.3 To determine w, a line is fit to log(G*) versus log(1+( c / R)v)1/v using the form given in Equation 12.10. The parameter w is the slope of the line. 1/ log( log 1 v v c g R w G (12.10) where e and w are best fit parameters. The G* at any critical value of interest within the range of measured data ( c) can be determined by first determining the R corresponding to c using Equation 12.5. Then, w

Proposed Test Methods 105 the corresponding G* is determined by applying the calculated wR value into Equation 12.4. 13. REPORT 13.1 Report the following: 13.1.1 Sample identification, 13.1.2 The type of emulsion and critical phase angle of interest ( c), 13.1.3 Dynamic shear modulus (G*) corresponding to c. 14. PRECISION AND BIAS 14.1 A minimum of two replicates should be tested for every emulsion residue and condition. 14.2 Test precision and bias are to be determined based on the results of inter-laboratory testing. 15. KEYWORDS 15.1 Emulsion residue, dynamic shear rheometer (DSR), dynamic shear modulus, parallel plate, frequency sweep test. 16. REFERENCES Marasteanu, M.O., and Anderson, D.A. (1999). “Improved Model for Bitumen Rheological Characterization,” Proceedings of the Eurobitume Workshop, Luxembourg. d d

106 Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments Proposed Modifications to ASTM D 3121, Standard Test Method for Tack of Pressure-Sensitive Adhesives by Rolling Ball Specifications Clause 6 – Add Subsection 6.2 stating: Sample Molds - A 320 mm long by 50 mm wide horizontal, flat steel plate (or steel tray) with four interconnected vertical retaining walls that form a watertight connection to the steel plate and extend vertically in a direction perpendicular to the steel plate should be used to confine the emulsion sample within the defined testing area. The height of the retaining walls should be sufficiently high to prevent overflow of the emulsion at the application rate being tested. Thin roofing felt paper should be attached to the horizontal surface of the steel plate for testing. Clause 6 - Revise Figure 2: Change height of stand apparatus from 65 mm to 15 mm. Clause 8 – Add Subsection 8.2 stating: For testing asphalt emulsions, apply a rate of emulsion into the sample mold for testing that is in agreement with the field emulsion application conditions of interest. Clause 9 – Add Subsection 9.2 stating: For asphalt emulsion testing, condition the steel sample mold with attached felt paper in an oven to 30°C prior to testing and separately heat the asphalt emulsion to its supplier-specified application temperature. Commentary Height of stand was lowered because the standard height stand caused the ball to roll beyond a length that was practical for testing. By lowering the stand height, the speed of the descent of the ball down the inclined ramp was decreased, leading to the ball rolling more practical measurable lengths during testing, with spray seal emulsions as the testing adhesive. For example, if testing in an area where an emulsion application rate of 0.45 liters per square meter (or 0.1 gallons per square yard) typically is used for spray sealing applications, this rate should be applied to the testing area. Heating the sample mold and felt paper ensures that the surface does not cool the asphalt emulsion at a faster rate than would occur in the field when the emulsion is applied to the existing pavement surface.

Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America’s Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation

TRA N SPO RTATIO N RESEA RCH BO A RD 500 Fifth Street, N W W ashington, D C 20001 A D D RESS SERV ICE REQ U ESTED N O N -PR O FIT O R G . U .S. PO STA G E PA ID C O LU M B IA , M D PER M IT N O . 88 Perform ance-Related Specifications for Em ulsified A sphaltic Binders U sed in Preservation Surface Treatm ents N CH RP Research Report 837 TRB ISBN 978-0-309-44616-7 9 7 8 0 3 0 9 4 4 6 1 6 7 9 0 0 0 0