Evaluating Applications of Field Spectroscopy Devices to Fingerprint Commonly Used Construction Materials (2013)

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230 A p p e n d i x Q This appendix summarizes the activities and testing results from Phase 3 of the R06B project titled “Evaluating Applica- tions of Field Spectroscopy Devices to Fingerprint Com- monly Used Construction Materials.” The appendix describes the Phase 3 objectives, followed by descriptions of the scope of work and experimental protocol. The example results of spectroscopic testing in the field are presented next. In addi- tion, preliminary conclusions are briefly discussed. phase 3 Objectives and Scope The main goal of Phase 3 was to verify the applicability of portable equipment identified as successful in Phase 2 to the testing of construction materials in field conditions at a level of quality that satisfies current quality assurance/quality con- trol (QA/QC) criteria. Effectively, the following were the objectives for field experiments in Phase 3: • Conduct field testing to demonstrate that the spectroscopic techniques recommended in Phase 2 can be transferred to field application. • Document all test procedures and protocols for the suc- cessful techniques and applications. • Recommend reasonable modifications to the equipment for improved implementation of the technologies. Table Q.1 summarizes project types, locations, and labor and equipment details for the field experiments conducted in Phase 3. equipment, Field Settings, and Testing protocols Compact ATR FTIR Spectrometer The Fourier transform infrared (FTIR) testing of all materials listed in Table Q.1 was done by the Bruker ALPHA spectrom- eter equipped with a single-reflection diamond attenuated total reflectance (ATR) accessory. This instrument was recog- nized as most successful in both fingerprinting pure com- pounds and chemicals and for qualitative evaluation of the chemical composition of complex composite materials. The only modification needed for field conditions was an external high-capacity battery with adapter cord supplied by the man- ufacturer. Typically, the ATR spectrometer was set in the trunk of a minivan and connected to a laptop and an external battery. No issues with power supply were detected during field trips. Furthermore, the ATR spectrometer was able to produce field spectra of the same precision and accuracy as laboratory spectra. It should be noted, however, that when the temperature was out of recommended range (18°C to 35°C), a longer warm-up period was required (up to 15 min versus 7 min standard). The ATR sampling mode was used for substances in liq- uid, thin film, or powder form, such as paints, chemical admixtures to portland cement concrete (PCC), asphalt binders and emulsions, and cement mortars. To obtain spectra for those materials, several drops of a liquid or approximately 0.5 g of a solid were placed on the ATR sam- pling plate and 24 co-averaged scans were collected at a resolution of 4 cm-1. In the case of thin films and powders, pressure was applied to the sample to ensure full contact with the ATR prism surface. The main issue with ATR test- ing of hot-mix asphalt (HMA) was relatively high (up to 30%) standard deviation from the mean of five replicates, mostly attributable to variability in particle size and mate- rial composition. The pulverized HMA and portland cement samples, however, did not yield variation higher than 15% of the mean. During field experiments, it was helpful to analyze the binder component of the HMA mixes using dichlorometh- ane (DCM) extraction. The DCM was found to be a more reactive, faster evaporating, and less toxic alternative to the AASHTO-standardized trichloroethylene solvent. The DCM extraction procedure included shaking 1:3 HMA–DCM Field Verification Results

231 Table Q.1. Scope of Work for Phase 3 Location/Contractor Project Type Material Category Sampling Methoda Equipment Labor Mansfield Depot, CT NA Structural coatings Scraping dry paint (solid) Fresh paint (liquid) Bruker ATR FTIR Team technician East Hartford, CT, Connecticut DOT HMA paving/ marking Pavement markings Scraping dry paint (solid) Fresh paint (liquid) Bruker ATR FTIR InnovaX XRF RTA Raman Team technician Mansfield Depot, CT NA Epoxy adhesives Dried compound (solid) Fresh compound (liquid) Bruker ATR FTIR Team technician Buckland St., Manchester, CT (site), East Granby (PCC plant), CT, Tilcon Connecticut, Inc. Precast PCC slab casting PCC with admixtures Fresh PCC (paste) Fresh admixture (from the plant) Bruker ATR FTIR, RTA Raman 3 Team technicians Site QC personnel New York DOT, Oldcastle Precast Plant, Avon, CT Precast wall block casting Curing com- pounds for PCC Before curing (liquid) After curing (dry) Bruker ATR FTIR RTA Raman Team technician Site QC personnel I-84 eastbound, north of Exit 36, Middletown, CT, All States Asphalt Group HMA Paving Polymer-modified asphalt binders and mixtures Fresh mix from the truck Extracted binder solution Bruker ATR FTIR (binders) Team technician Route 160, Rocky Hill, CT, All States Asphalt Group Novachip seal paving Polymer-modified asphalt emulsions Before breaking (liquid) Bruker ATR FTIR Team technician Site QC personnel Route 89, Mansfield Center, CT Rubberized chip seal paving Polymer-modified asphalt binders Binder from the truck Coated aggregate from the truck Binder from the road Bruker ATR FTIR Team technician New Haven, CT Gateway Termi- nal, All States Asphalt Group NA Antistripping agents Antistripping agent from tank Antistripping-modified binder Bruker ATR FTIR Team technician Note: NA = not available; DOT = Department of Transportation; HMA = hot-mix asphalt; ATR = attenuated total reflectance; FTIR = Fourier transform infrared; XRF = X-ray fluorescence; RTA = Real-Time Analyzers; PCC = portland cement concrete; QC = quality control. a See Appendix I for details. solution for 1 to 2 min and filtering the solution through the regular two-layer tissue paper. To collect ATR spectra, several drops of the solution were placed on the ATR prism and left for 2 min to allow the DCM to evaporate completely. Next, the ATR absorbance spectrum was collected in the same fash- ion as the rest of liquid materials. Portable XRF The portable Innov-X Alpha X-ray fluorescence (XRF) analyzer owned by the team was used for testing traffic paints in field applications. Exchangeable alloy, soil, and mining measurement modes allowed for the detection of typical heavy metal concen- trations in both liquid (laboratory tested) and solid (in situ tested) paint samples. To obtain concentration quantities, cured pavement markings were tested by applying the XRF instrument to the surface and collecting data over 90-s time intervals. Liq- uid paint samples were collected from the tank and tested in the laboratory (on arrival from the field) in their as-received state by placing 15 to 30 g of each sample in an XRF sample holder. Compact Fourier Transform Raman Spectrometer Field measurements of Raman spectra of traffic paints, curing compounds, and chemical admixtures to PCC were recorded using Real-Time Analyzers Inc.’s (RTA’s) Fourier transform Raman spectrometer operating at 1,064-nm laser excitation at 500 mW. Resolution was set at 8 wave numbers (cm-1) for all collections. Collection was performed using RTA’s FTR soft- ware operating in continuous collection mode. A 5-m steel- jacketed fiber optic probe was used for collection. Given the potential interference of ambient light, spectral analysis con- sisted of first evaluating those contributions and determining the appropriate background removal techniques to yield spec- tra consistent with those of controlled laboratory conditions. Initial evaluation of field conditions as they pertain to safety for outdoor laser operations was performed. While the Raman spectrometer is not in collection mode, the laser shut- ter is always closed to ensure safe handling and to minimize potential exposure. Only when the probe tip has been securely

232 applied to a sampling surface is the laser shutter opened. Additional precautions regarding safe handling of lasers for outdoor operation can be found in the approved American National Standard Institutes publication, ANSI Z136.1 (2007). Certain materials may require modifications to the nominal hazard zone (NHZ) calculations for use in transpor- tation specific applications. All personnel within the NHZ must be made aware of the operation of the laser, advised of the potential hazards, and provided with proper safety con- trol measures. For instance, the light reflected by any material with increased specular or diffuse reflectance may damage eyes of an operator. Other circumstances may arise in field conditions that could increase the likelihood of laser expo- sure and it is advised that operators be well versed in the safe operation and handling of laser equipment. For the current study, operators were equipped with Occupational Safety and Health Administration–approved eyewear and no additional personnel were present. More details on Raman measure- ments and sample handling are provided in this appendix. Field Test Description and Results Epoxy Coatings and Adhesives: ATR Objectives: Fingerprinting (verification of chem- ical composition) of fresh and dried epoxy samples Team operators: Iliya Yut Field operator: Not available (NA) Equipment: Bruker ALPHA ATR Test date: September 23, 2011 Location: CAP Lab, Mansfield Depot, Con- necticut Contractor: NA Project type: NA Material collected: Carbozinc 859 and Scotchkote (epoxy structural coatings) and Ultrabond 1100 (epoxy adhesive)— individual components Sample type: Liquid (freshly mixed compounds), thin films (dried structural coatings on the metal surface), solids (adhesives) Ambient temperature: 23°C Three types of epoxies were evaluated by the Bruker ALPHA ATR spectrometer to investigate the feasibility of fingerprint- ing their chemical composition in situ: (1) three-part, organic, zinc-rich epoxy coating system (Carbozinc 859), (2) fusion- bonded epoxy (Scotchkote), and (3) two-part high-strength epoxy bonding adhesive (Ultrabond 1100). The primary objective of the experiment was to obtain a signature spec- trum for each material under the field conditions in Phase 3. The signature spectra obtained in Phase 3 were compared with those from the preliminary testing in the laboratory (Phase 2). In addition, changes in the ATR spectra of the applied epoxies during the drying process were analyzed. Because of Connecticut Department of Transportation (DOT) limitations, the research team did not obtain access to any site projects involving bridge construction. Instead, the samples for Phase 2 testing were fabricated by mixing ingre- dients in accordance with manufacturer’s instructions and applying the coating to a metal plate. Nevertheless, all epoxy samples were tested using the same equipment setup as for the other materials (i.e., the ATR spectrometer was set in the back of a van and the external battery was used). Figure Q.1 compares the ATR spectra of the two Scotchkote samples collected during laboratory (Phase 2) and field Figure Q.1. Comparison of the ATR spectra of Scotchkote epoxy coating samples collected in Phases 2 and 3.

233 (Phase 3) stages. Note that two different Bruker ALPHA ATR instruments of the same model were used to obtain the mate- rial spectra 18 months apart between testing events. One can confidently see the absence of any visible differences between the laboratory and field sample based on the location of the characteristic peaks shown in Figure Q.1. Similarly, a perfect match between the laboratory and field samples was found for the Carbozinc 859 coating system. Once the freshly mixed epoxy coating was applied to a metal plate, ATR spectra of the material scraped from the plate surface were collected immediately and after 20 and 60 min, respectively. The three spectra shown in Figure Q.2 indicate the evaporation of toluene solvent by a drastic decrease in the infrared (IR) absorbance at 738 and 698 cm-1, and the hardening and oxidation of the epoxy base by an increase in the absorbance at 1,728 and 1,276 cm-1. Neverthe- less, the presence of epoxy resin can be tracked even after an hour of air-curing, as evident by the IR absorption peaks at 1,662, 1,608, and 1,580 cm-1. Similarly to the epoxy structural coatings, the laboratory and field samples of the Ultrabond 1100 adhesive bonding system are superimposed in Figure Q.3. Once again, all char- acteristic peaks from the lab sample produced in Phase 3 are located within 5 cm-1 wave number from those in the sample Figure Q.2. Change in the ATR spectra attributable to curing of Carbozinc 859 epoxy coating system. Figure Q.3. Comparison of the ATR spectra of Ultrabond 1100 epoxy adhesive samples collected in Phases 2 and 3.

234 tested in Phase 2 18 months earlier by a different instrument. Figure Q.4 shows that the adhesive can be positively iden- tified within 10 min (onset time) from the moment of application. Traffic Paints: XRF Objectives: Quantification of elemental compo- sition of traffic paints (see example in Figure Q.5) Team operators: Chad Johnston Field operator: NA Equipment: Innov-X Systems XRF Test date: September 14, 2011 Location: East Hartford, Connecticut Contractor: Connecticut DOT District 1 Pave- ment Marking Department Project type: Test of white and yellow pavement markings Material collected: White and yellow Ennis Fast Dry water- borne traffic paints Sample type: Liquid paint samples collected directly from paint applicator truck (lab analysis) and painted lines (field analysis) Ambient temperature: 22°C The concentrations of selected elements in Ennis white and yellow traffic paints are presented in Table Q.2 and Table Q.3, respectively. Three separate measurements were recorded for each paint strip. Each individual measurement has instrument-determined error values (±) that are element specific. The average elemental concentrations and standard deviations were computed for all sample types. Both white and yellow traffic paints are composed of greater than 10% Ca. This open-ended result is likely attributable to the high Ca signal that apparently saturated the XRF detector at 10% detection. The Ca is likely in the form of CaCO3, which is added as a pigment extender for TiO2. Thus, if one can assume that all of the Ca in the samples is in the form of CaCO3, this translates to a CaCO3 concentration of greater than 25%. The white paint contains an average of 64,772 ppm Ti, which is twice that of the yellow paint, which averaged 27,717 ppm Ti. This is attributed to the higher requirement of the white pigment, rutile. Titanium concentrations in the field test correspond to a TiO2 content of 11% and 5% in white and yellow paints, respectively. The yellow pigment may be organic based (e.g., Yellow 65), which is undetectable via XRF, or iron (Fe) based (e.g., Fe-oxide). This latter pos- sibility is supported by the average Fe concentrations of 769 and 3,100 ppm detected in white and yellow paints, respectively. Measurements of the asphalt (i.e., the unpainted pavement surface) (see Table Q.4), and fresh white and yellow paint samples (Tables Q.5 and Q.6, respectively) were collected to evaluate possible interference with the road markings by the underlying substrate. XRF measurements in the field and fresh paint samples in the lab should yield comparable results, and, if not, a likely possibility would be the unwanted signal contribution from the pavement. This possibility arises because of the complexity of X-ray penetration depth, which ranges from micrometers to millimeters. Thus, if Figure Q.4. Change in the ATR spectra attributable to curing of Ultrabond 1100 epoxy adhesive.

235 Figure Q.5. Device calibration (top left ), white paint testing (top right ), zoom on XRF instrument (bottom left ), and image of XRF result screen (bottom right ). incident X-rays penetrated beyond the paint layer into the asphalt, the measured data may not accurately reflect the true elemental composition of the paint, rather some unknown combination of the paint and the pavement. The results show slightly increased K, Fe, and Ti concentrations in the field versus the laboratory, which could be attributable to the asphalt. Alternatively, the discrepancy may be because the lab samples were fresh and thus had higher moisture content than that of the dried marking in the field. Water is undetectable via XRF but would still contribute to the overall mass and essentially dilute the concentrations of elements.

236 Table Q.2. Elemental Composition of White Traffic Paint Strip as Determined by XRF Element Sample 1 Sample 2 Sample 3 Average Concentration (ppm) ± Concentration (ppm) ± Concentration (ppm) ± Concentration (ppm) SD Ca >10% 1% >10% 1% >10% 1% >10% na K 4,791 448 5,668 394 4,811 383 5,090 676 S ND na 10,409 3,213 ND na 10,409 na Ti 62,051 1,207 65,260 1,045 67,005 1,071 64,772 2,988 Ba 587 102 770 87 818 89 725 142 Mn ND na ND na ND na ND na Fe 669 22 794 20 843 20 769 106 Zn 24 4 18 4 ND na 14 16 Sr 112 3 147 3 197 4 152 53 Zr 92 3 56 2 84 3 77 25 Note: ND = not determined. Table Q.3. Elemental Composition of Yellow Traffic Paint Strip as Determined by XRF Element Sample 1 Sample 2 Sample 3 Average Concentration (ppm) ± Concentration (ppm) ± Concentration (ppm) ± Concentration (ppm) SD Ca >10% 1% >10% 1% >10% 1% >10% na K 5,109 333 4,170 308 4,208 306 4,496 614 S ND na ND na ND na ND na Ti 27,774 467 27,894 457 27,484 448 27,717 295 Ba 343 54 224 52 315 52 294 81 Mn ND na ND na ND na ND na Fe 3,803 59 2,644 42 2,854 45 3,100 718 Zn 79 5 78 5 77 5 78 1 Sr 168 3 156 3 144 3 156 15 Zr 90 3 90 3 96 3 92 5 Note: ND = not determined. Table Q.4. Elemental Composition of Asphalt Adjacent to Paint Strips Element Sample 1 Sample 2 Sample 3 Average Concentration (ppm) ± Concentration (ppm) ± Concentration (ppm) ± Concentration (ppm) SD Ca 39,874 674 64,408 1,077 35,299 598 46,527 21,632 K 9,769 323 8,772 335 10,007 319 9,516 909 S 7,521 1,514 7,358 1,783 8,184 1,502 7,688 607 Ti 5,124 165 7,230 216 3,978 149 5,444 2,322 Ba 365 37 578 47 414 36 452 145 Mn 969 24 1,217 30 786 22 991 306 Fe 45,131 636 65,054 968 51,450 709 53,878 13,002 Zn 124 7 123 7 70 5 106 42 Sr 133 3 146 3 122 3 134 17 Zr 104 3 85 3 82 3 90 14

237 Traffic Paints: ATR Objectives: Fingerprinting of the traffic paint samples in the field (see example in Figure Q.6) Team operators: Iliya Yut Field operator: NA Equipment: Bruker ALPHA ATR Test date: September 1, 2011 Location: East Hartford, Connecticut Contractor: Connecticut DOT District 1 Pave- ment Marking Project type: Test white and yellow line marking Material collected: Ennis waterborne Fast Dry paint (white and yellow) Sample type: Liquid from tank, thin film from sur- face (freshly painted and old) Ambient temperature: 26°C Table Q.5. Elemental Composition of White Traffic Paint as Determined by In-Lab XRF Element Sample 1 Sample 2 Average Concentration (ppm) ± Concentration (ppm) ± Concentration (ppm) SD Ca >10% 1% >10% 1% >10% na K 3,296 298 2,596 285 2,946 495 S ND na ND na ND na Ti 49,598 755 48,818 735 49,208 552 Ba 624 71 795 71 709.5 121 Mn ND na ND na ND na Fe 570 15 589 15 579.5 13 Zn ND na ND na ND na Sr 121 3 123 3 122 1 Zr 39 2 35 2 37 3 Note: ND = not determined. Table Q.6. Elemental Composition of Ennis Yellow Traffic Paint as Determined by In-Lab XRF Element Sample 1 Sample 2 Average Concentration (ppm) ± Concentration (ppm) ± Concentration (ppm) SD Ca >10% 1% >10% 1% >10% na K 2,819 256 3,086 261 2,953 189 S ND na ND na ND na Ti 21,505 359 22,000 366 21,753 350 Ba 369 46 316 46 343 37 Mn 25 6 ND na 13 18 Fe 2,177 35 2,248 36 2,213 50 Zn 62 4 70 5 66 6 Sr 127 3 133 3 130 4 Zr 86 2 91 2 89 4 Note: ND = not determined.

238 Figure Q.6. Application of white paint (top left ), sampling from the tank (top right ), sampling from the surface (bottom left ), and sample placed on ATR plate (bottom right ). The ATR spectra of Ennis Fast Dry white paint samples from tank, newly painted white line, and the old white line are compared in Figure Q.7. The waterborne vinyl acrylate structure of a liquid sample from a tank can be easily iden- tified by the medium-wide water-associated (~3,400, ~3,250, and ~1,640 cm-1) and strong sharp carboxylate- associated (~1,730 and ~875 cm-1) absorption bands. Note that the evaporation of water can be tracked by observing significant reduction in the intensity of the OH vibrations in the freshly painted white line (about 15 to 30 min after application). Consequently, no water can be detected in the old paint several months after application. The waterborne polyacrylic paint in discussion can definitely be finger- printed by matching multiple peaks in the region between 400 and 1,800 cm-1 to a library spectrum as shown in Figure Q.8. PCC and Chemical Admixtures: ATR Objectives: Fingerprinting of chemical admix- tures and verification of their pres- ence in a PCC sample (see example in Figure Q.9) Team operators: Chad Johnston, Alexander Bernier, Russell Duta Field operator: Site Foreman Equipment: Bruker ALPHA ATR Test date: July 11, 2011 Location: Park-and-Drive facility, Buckland Street at Buckland Hill Drive, Manchester, Connecticut Contractor: Tilcon Connecticut Inc. (East Granby PCC Plant)

239 Figure Q.7. Comparison of the ATR spectra of Ennis Fast Dry white paint sampled from tank, freshly applied white marking, and old white line surface. Figure Q.8. Matching ATR spectrum of Ennis Fast Dry white paint to a library spectrum. Project type: Precast PCC slab casting Material collected: PCC, set-accelerating, air-entraining, and high-range water-reducing admixtures Sample type: Solid (fresh PCC from cast), liquid (chemical admixtures from plant) Ambient temperature: 33°C The ATR spectra of air-entraining, high-range water- reducing (HRWR), and set-accelerating admixtures are shown in Figures Q.10 through Q.12, respectively. Each fig- ure superimposes spectra of three samples for each admixture: 1. Sample from the vendor’s container during the laboratory testing in Phase 2, 2. Sample collected from a PCC plant and tested in the field (Phase 3), and 3. Sample collected from a PCC plant and tested in the labo- ratory on return from the field (Phase 3).

240 Figure Q.9. Pouring of PCC into a slab mold (top left ), sampling PCC (top right ), placing PCC sample onto ATR plate (bottom left ), and sampling of chemical admixture (bottom right ). Figure Q.10. Fingerprinting of air-entraining chemical admixture.

241 The characteristic absorption peaks associated with the tall oil component of the AIR chemical (2,929, 2,857, 1,543, 1,466, and 1,402 cm-1) can be easily identified on each spectrum in Figure Q.10. On the basis of the analysis of spectra shown in Figure Q.11, the HRWR admixture collected from the plant (vendor is unknown) can be positively identified as ADVA 190, which was supplied by W. R. Grace & Co. for preliminary laboratory testing in Phase 2. The nonchloride SicaSet accel- erator (NCL in Figure Q.12) can be distinguished from Accel- guard 80 chemical by the presence of the thiocyanate-related band at 2,070 cm-1, which is absent in Accelguard 80. Note that the calcium nitrate component in both admixtures (required by the ASTM standards) is identified by the prominent peak at about 1,330 cm-1 with a distinctive shoulder at 1,420 to 1,410 cm-1. It should be noted that two different Bruker ALPHA ATR instruments were used to perform FTIR testing in laboratory and in the field. Nevertheless, the very precise identification of the characteristic absorption peaks for all admixtures in discussion (within 5 cm-1 wave number) was possible. Thus, Figure Q.11. Fingerprinting of high-range water-reducing chemical admixture. Figure Q.12. Fingerprinting of nonchloride set-accelerating chemical admixture.

242 it can be concluded that the FTIR spectra of chemical admix- tures for PCC can be standardized without concern for preci- sion and accuracy of the measurements. One of the objectives of the FTIR testing of PCC was veri- fication of the admixture’s presence in a fresh PCC mix. The preliminary results in Phase 2 indicated this task as a very challenging one, primarily because of usually very low (less than 1% by weight) concentration of the admixtures. How- ever, in knowing that HRWR chemicals preserve rate of hydration, the presence of HRWR can be verified by the rela- tively strong IR absorption peaks at 933, 874, and 828 cm-1 associated with formation of the primary hydration product [calcium–silicate–hydrate (C-S-H)], as shown in Figure Q.13. A closer look at the zoomed-in spectra in the region between 1,500 and 1,300 cm-1 reveals relatively weak but visible peaks associated with admixtures. For instance, the three peaks at 1,455, 1,280, and 1,250 cm-1 can be related to the presence of HRWR, while the two peaks at 1,410 and 1,330 indicate pres- ence of NCL accelerator. Curing Compounds: Attenuated Total Reflectance Objectives: Fingerprinting and verification of presence on the PCC surface (see example in Figure Q.14) Team operators: Iliya Yut Field operator: PCC plant technician Equipment: Bruker ALPHA ATR Test date: September 1, 2011 Location: Avon, Connecticut Contractor: Oldcastle Precast Project type: In-plant precast foundation block manufacturing Material collected: TAMMSCURE curing compound Sample type: Liquid from container, powder from freshly covered PCC surface, powder from dried PCC surface Ambient temperature: 23°C Figure Q.15 superimposes the ATR spectra of the pure chem- ical (TAMMSCURE curing compound), the sample scratched from the freshly covered PCC surface, and the sample of dried PCC surface. Each spectrum represents an average of three rep- licate probes from each sample. It is obvious from Figure Q.15 that characteristic peaks (2,938, 2,856, 1,455, and 1,374 cm-1) associated with hydrocarbon resin and aliphatic naphtha com- ponents of TAMMSCURE (see material safety data sheets) can be tracked on the ATR spectra of both freshly covered and dried PCC surfaces to which the curing compound have been applied. Figure Q.16 compares ATR spectrum of TAMMSCURE tested from the dispenser in the plant with the spectrum of Sealtight from the manufacturer’s package tested in the labo- ratory. An identical location of the peaks at 2,926, 2,851, and 1,455 cm-1 on both spectra indicates their similar chemical composition (emulsified hydrocarbon resin). However, the low intensity of those peaks relative to the water-associated bands centered around 3,400 and 1,650 cm-1 on the TAMMSCURE spectrum suggests higher water content (dilution) in the field application of this material. A sample collected in the plant and tested a day later in the laboratory yielded an ATR spec- trum identical to that of its original condition. Polymer-Modified Hot-Mix Asphalts: ATR Objectives: Verification of polymer presence and quantification Team operators: Chad Johnston and Iliya Yut Figure Q.13. ATR spectra of hydrated PCC sample with HRWR and NCL admixtures.

243 Figure Q.14. Equipment setup (top left ), pure TAMMSCURE sampling (top right ), surface sampling (bottom left ), and sample on ATR plate (bottom right ). Figure Q.15. ATR spectra of TAMMSCURE curing compound before and after application to a PCC surface.

244 Field operator: NA Equipment: Bruker ALPHA ATR Test date: August 16, 2011 Location: Farmington, Connecticut, I-84 East- bound, North of Exit 36 Contractor: All States Asphalt Group Project type: 2-in HMA overlay with styrene– butadiene–styrene (SBS)-modified PG 76-22 binder Material collected: HMA mix from paver, tack coat from pavement surface Sample type: Solid HMA and liquid tack coat (emulsion) Ambient temperature: 28°C Note: The project took place at night (9:00 p.m.) and no pho- tos were taken. Figure Q.17 presents the normalized (to 2,920 cm-1 peak value) ATR spectra of two samples taken from the paver within 15 min of each other (two separate trucks unloaded). One can see that absorption peaks of the two samples are matching, which suggests they have identical chemical Figure Q.16. Comparison of the field TAMMSCURE and laboratory Sealtight ATR spectra of curing compound. Figure Q.17. ATR spectra of HMA field samples.

245 composition. The peak at about 2,180 cm-1 indicates the presence of carbon dioxide from entrapped hot air. In addi- tion, minor oxidative hardening resulting from mixing and placement of the HMA can be detected by the peak at about 1,700 cm-1. The rest of the peaks are associated with the binder (2,961, 2,921, 2,853, ~1,600, 1,455, and 1,375 cm-1) and filler and aggregates (~1,000, 793, 637, 585, 530, and 467 cm-1). A closer look at the ATR spectrum in Figure Q.18 allows for the identification of weak but not negligible peaks associated with the presence of SBS polymer in the PG 76-22 binder. Figure Q.18 compares the ATR spectrum of the SBS- modified HMA sample collected from the field with that of a sample mixed in the laboratory. A close look at the two spectra allows for identifying weak but not negligible peaks associated with presence of SBS polymer in the PG 76-22 binder. It should be noted that the polybutadiene peak at 967 cm-1 is likely to be obscured by the strong and wide band centered around 1,000 cm-1 that is associated with the silicate component of the aggregates. Furthermore, the peak near 700 cm-1 can be associated with quartz presence in sili- cious aggregates rather than with polystyrene-related IR absorptions. Therefore, quantification of SBS content in the fresh mix appears to be impractical for two reasons. First, the weight percent content of the polymer compared with the mix sam- ple weight is extremely low (around 0.002 wt %), which makes identifying the SBS peaks a very challenging task. Second, the polymer content is usually governed by a binder grade speci- fication. Therefore, it appears logical to verify polymer con- tent in an extracted binder sample as discussed in the next section. Identification of Polymer in Asphalt Binder Extracted from HMA–ATR Objectives: Verification of polymer presence Team operators: Iliya Yut Field operator: NA Equipment: Bruker ALPHA ATR Test date: May 23, 2011 Location: Rocky Hills, Connecticut, Route 160 Westbound Contractor: All States Asphalt Group Project type: Novachip seal Material collected: SBS-modified HMA mix from paver Sample type: Liquid (1:3 stabilized DCM solution) Ambient temperature: 23°C Special Sample Preparation About 5 g of HMA passing No. 16 (1.18-mm) sieve size were added to 15 mL of stabilized DCM for spectroscopic applica- tions, manually shaken for 2 min, and then left for 15 min to allow sedimentation of suspended filler particles. The liquid phase of the solution was probed by pipetting two to three drops on the ATR sampling plate. The ATR spectra of the sample were collected twice: immediately and within 1 to 2 min from the moment of placement. Results Figure Q.19 compares the ATR spectra in the fingerprinting region (1,800 to 400 cm-1) of a DCM-extracted PG 76-22 binder sample obtained immediately and 1 min after placing the sample on the ATR plate. It is shown that the only three Figure Q.18. Zoom on SBS-associated absorption bands in laboratory and field samples of polymer-modified HMA.

246 characteristic absorption peaks attributed to DCM, which are at 1,263, 739, and 706 cm-1, do not interfere with characteristic peaks of the aliphatic component of the binder (1,455 and 1,377 cm-1) or with the absorption of filler particles. However, the DCM solvent peaks do obscure the signal from the aro- matic hydrocarbons (860 to 725 cm-1) and, if present, from the polystyrene component of the SBS polymer (expected around 700 cm-1). When sample is allowed to cure for 1 min, the solvent evaporates completely, making it possible to iden- tify both binder aromatics and the SBS-related peak. Polymer-Modified Asphalt Emulsions—ATR Objectives: Verification of polymer presence (see example in Figure Q.20) Team operators: Chad Johnston and Iliya Yut Field operator: John DaDalt Equipment: Bruker ALPHA ATR Test date: May 23, 2011 Location: Rocky Hills, Connecticut, Route 160 Westbound Contractor: All States Asphalt Group Project type: Novachip seal Material collected: CRS-2 polymer-modified emulsion, ready-coated seal stone. Sample type: Liquid emulsion, solid-coated stone particle Ambient temperature: 15°C Figure Q.21 superimposes the ATR spectra of the polymer- modified emulsion CRS-2 in two states: (1) sampled from the tank and (2) applied to stone aggregate (Novachip seal technology). The two main emulsion components are easily identified by strong and wide water bands centered around 3,300 and 1,640 cm-1 and doubled aliphatic binder peaks at about 2,920, 2,850, 1,455, and 1,375 cm-1. The SBS additive can be detected by two characteristic peaks at 967 and 700 cm-1 associated with polybutadiene and polystyrene, respectively. The spectra of the Novachip stone coated by the CRS-2 emul- sion clearly indicate the absence of water after the emulsion breaks on the aggregate. Note that the wide band at 1,600 cm-1 is associated with the aromatic carbon skeleton of the binder. In regard to the polymer, the polybutadiene peak is obscured by the signal from silicate component of the aggregate (990 cm-1); however, the SBS presence can still be verified by a weak yet distinctive peak at about 695 cm-1. Figure Q.22 compares the ATR spectra of two polymer- modified asphalt emulsions tested in the laboratory and in the field by two separate Bruker ALPHA ATR spectrometers. Note that practically no difference in chemical composition of the two samples is indicated. However, the higher water con- tent in CRS-1P relative to CRS-2 can be deduced by the signifi- cantly lower intensity of the absorption bands associated with the aliphatic binder. Nevertheless, the presence of polymer is clearly indicated by the SBS-related peaks at 966 and 695 cm-1. Antistripping Agents—ATR Objectives: Fingerprinting and verification of antistripping presence in asphalt binder Team operators: Iliya Yut Field operator: NA Figure Q.19. Identification of SBS polymer in asphalt binder PG 76-22 extracted from HMA.

247 Figure Q.20. Sampling emulsion (top left ), Novachip application (top right ), ATR testing setup (bottom left ), and sample placement (bottom right ). Equipment: Bruker ALPHA ATR Test date: September 9, 2011 Location: New Haven Gateway Terminal, Connecticut Contractor: All States Asphalt Group Project type: NA Material collected: AD-here Regular Sample type: Liquid Ambient temperature: 25°C To identify the type of antistripping agent, a trip to the stor- age facility was undertaken and a sample of the AD-here chemical was collected and tested using the ATR spectrometer under in situ conditions. The obtained absorbance spectrum was compared with that of a previously collected sample of AD-here LOF 65 antistripping agent, as shown in Figure Q.23. It is easily observed that the field sample yields stronger absorption bands at 2,925, 2,854, and 1,459 cm-1 and signifi- cantly lower absorption at wave numbers associated with

248 Figure Q.21. ATR spectra of pure emulsion from tank (CRS-2) and Novachip coated aggregate. Figure Q.22. ATR spectra of polymer-modified emulsions. amido- (1,650 to 1,550 cm-1) and amino- (2,813, 1,130, and 1,070 cm-1) functional groups. Such a result suggests that the field sample may be contaminated with asphalt binder or, alter- natively, diluted by an aliphatic solvent to reduce the viscosity of the antistripping agent. An additional objective of this study was to identify the presence of an antistripping agent in an asphalt binder. Because no similar field projects were available at the time, a modified binder was produced by mixing nonmodified PG 64-22 binder with the AD-here chemical obtained from a storage facility. Because of the low concentration of the antistripping agent and very similar chemical structures of AD-here and PG 64-22 binder, it was not possible to posi- tively identify the presence of the additives in the ATR-tested sample. RTA’s Raman Results Samples previously identified as having sufficient Raman scattering were chosen to test the applicability of Raman analyses in the highway construction field environment. Six samples from the previous set were chosen from the Phase 1

249 Figure Q.23. Comparison of the two AD-here antistripping samples with different chemical compositions. Figure Q.24. RTA’s portable Raman analyzer. Raman Shift, cm−1 R el at ive In te ns ity library, namely, the existing white and yellow line pavement markings, TAMMSCURE curing compound, and the follow- ing PCC chemical admixtures: Accelguard 80 (A-80), air- entrainer Air 200, and Retarder R75. Additionally, field-specific conditions were measured to allow for corrections to the spec- tra. The detector used has a range of 1,064 to 1,700 nm to track Raman shifts from the excitation at 1,064 nm. This region also corresponds to natural ambient near-infrared light and, as such, additional measurements aid in the removal of stray light contributions. To simplify measurement collec- tion, a continuous mode was used and sample collection times were logged accordingly and later matched up with the appropriate sample. Given the potential interference of ambient light, spectral analysis consisted of first evaluating those contributions and determining the appropriate background removal techniques to yield spectra consistent with those of controlled laboratory conditions. Figure Q.24 shows the Raman spectra of a sample

250 Figure Q.25. White paint measured on glass corrected to remove fluorescence and ambient light contributions. Raman Shift, cm−1 R el at ive In te ns ity of TAMMSCURE before (top) and after (bottom) removal of the contributions from ambient light. TAMMSCURE Raman spectrum recorded in the field (top green trace) shows con- tributions from ambient light (broad band from 1,400 to 2,000 cm-1). The bottom trace shows the corrected spectrum calculated using RTA’s Raman Vista advanced calculator and subtraction of background. Other spectra are shown with corrections only (see Figures Q.25 through Q.30), with spec- tra calculated on the basis of selections from the continuous scanning, and subsequently averaged before doing a baseline, fluorescence, or ambient light removal if necessary. Table Q.7 summarizes the results of Raman testing in terms of successful identification of maximum characteristic peaks and signal-to- noise ratios for the materials in discussion. Figure Q.26. Yellow paint measured on glass corrected to remove fluorescence and ambient light contributions. Raman Shift, cm−1 R el at ive In te ns ity

251 Figure Q.27. White paint (old) corrected to remove fluorescence and ambient light contributions. Raman Shift, cm−1 R el at ive In te ns ity Figure Q.28. A-80 spectrum averaged for three collections (12 equivalent scans, no background subtraction necessary). Raman Shift, cm−1 R el at ive In te ns ity

252 Figure Q.29. Air 200 spectrum averaged for 20 scans (five spectra measured at four scans, no background subtraction necessary). Raman Shift, cm−1 R el at ive In te ns ity Figure Q.30. R75 spectrum averaged for 40 scans (10 spectra measured at four scans, no background subtraction necessary). Raman Shift, cm−1 R el at ive In te ns ity

253 Table Q.7. Raman Spectral Results and Signal-to-Noise Ratio Calculations Material Category Sample ID Success (Yes/No) Relative Signal Intensity Wave number Peak (cm1) Noise (SD) Signal- to-Noise Ratio Field-tested material White paint Yes 4.00 1086 0.0435 85 Yellow paint Yes 1.00 1295 0.036 27 TAMMSCURE Yes 1.19 1,110 0.0116 8 A-80 Yes 1.29 2,843 0.040 0.71 Air 200 Yes na na na na Retarder R75 Yes na na na na White paint strip (old) Yes 2.43 443.4 0.058 46 Note: na = not applicable. preliminary Conclusions On the basis of the results presented, it can be concluded that, predominantly, the experiments conducted in the field (Phase 3) verified the methodology and reproduced the results similar to those in the laboratory phase. Specifically, the compact ATR spectrometer, handheld XRF instrument, and RTA’s Raman analyzer were successful in the identifica- tion of chemical structure, or fingerprinting, of both simple and complex organic compounds such as epoxy coatings and adhesives, curing compounds, and waterborne traffic paints. Furthermore, such complex composite material as PCC yielded meaningful ATR absorbance spectra, which allowed for the identification of chemical admixtures in fresh mix samples, provided their concentrations were higher than 0.5 wt %. Verification of polymer presence in asphalt binders and emulsions was possible using the ATR spectrometer. Although identification of polymer in an HMA mix presented a chal- lenge, the fast binder extraction procedure in the field using DCM solvent appeared to be a feasible alternative to direct evaluation of polymer-modified HMA.