Rolling Thin Film Oven Test Research Articles

Effects of Thermoplastic Block Copolymers on Rheology of Asphalt

The Dynamic mechanical properties of thermoplastic block copolymer modified asphalt were investigated. A viscosity graded AC-20 asphalt cement and five styrene-butadiene block copolymers with linear and radial structures were mixed at three concentration levels to yield 15 modified blends. The effect of short-term aging on rheological properties was simulated by the rolling thin film oven test (RTFOT) procedure. After establishing the linear viscoelastic range of response through performing stress sweeps, frequency sweeps were carried out at temperatures ranging from 5 to 75 deg C and frequencies between 0.063 and 188.496 rad/s. Using the time-temperature superposition principle, isothermal response curves were reduced to dynamic master curves of complex modulus and loss tangent. Relaxation spectra were developed by means of an approximate interrelationship between viscoelastic functions. Effects of polymer type and content, and aging condition on viscoelastic response were studied. Addition of polymer was found to substantially broaden the relaxation spectra. With increasing polymer contents, significant changes in the complex modulus and loss tangent at intermediate and low frequencies were observed. At higher frequencies the variations were less apparent and were found to be highly influenced by the aging condition of the modified binders. Evaluation of the measured shift factor data indicated that in all cases a Williams-Landel-Ferry (WLF) equation with universal constants could reasonably represent the temperature dependence of response.

Characterizing Asphalt Volatility

Asphalt volatility is one of several factors that can affect the degree of environmental discharge and worker fume exposure that occurs during hot-mix manufacturing and construction. Fundamental volatility measurements using vapor pressure generally are not practical for asphalt because of its low volatility. Eight potential asphalt volatility tests were considered: thin film oven test, rolling thin film oven test, Cleveland open cup flash point, steam distillation, thermogravimetric analysis, German rotating flask test, vacuum flask distillation, and high-temperature simulated distillation by gas chromatography. Many of these tests are affected by testing artifacts such as oxygen addition, skin formation, and thermal degradation. The procedure, standardization, and validity of each test are discussed. Existing data are reviewed and new data are presented to demonstrate the relationships among these tests. On the basis of available information, it is concluded that the best empirical (condition-dependent) volatility test is the German rotating flask test conducted with an inert gas, and the best compositional (conditionindependent) volatility test is high-temperature simulated distillation by gas chromatography.

Laboratory Aging Methods for Simulation of Field Aging of Asphalts

This study evaluated several promising laboratory aging methods for simulation of field aging of asphalts. The rheological properties of an asphalt binder after aging in the thin-film oven test (TFOT) and rolling thin-film oven test (RTFOT) processes performed at three different temperatures were compared with those after the California tilt oven, Strategic Highway Research Program (SHRP) pressure air vessel and actual field aging. Nine different modified asphalts made with five different types of polymer modifiers were also evaluated after being subjected to the TFOT and RTFOT at three different temperatures. The results indicate that the RTFOT aging process performed at a temperature of 185° can simulate a 1-yr field aging effect, and the California tilt oven process for a duration of 168 h can simulate 8-yr field aging under typical Florida conditions.

Thermal decomposition of asphalt sulfoxides

The pyrolytic decomposition of asphalt sulfoxides was studied. The rate of decomposition was found to be several orders of magnitude less than that of simple model sulfoxides reported in the literature. The rate of loss is not negligible at 163°C, the temperature of a commonly used asphalt accelerated ageing procedure (rolling thin film oven test). Gel permeation and viscosity measurements indicate that polymerization reactions or products of sulfoxide decomposition act to offset the changes in physical properties expected on loss of sulfoxides.

95/03555 Hydrodynamic behaviour of a liquid-solid fluidized-bed reactor for the bioconversion of coal particles to liquid products

Aging changes the chemistry of bitumen and this adversely affects bitumen’s adhesion with aggregate. For this reason, the use of pull-off test was proposed to evaluate bitumen’s adhesion during different aging stages. In this study, the pull-off test method is used to evaluate the effects of aging on a 60/70 penetration grade bitumen and binders modified with 2 and 4% halloysite nano-tube (HNT). The short-term aging (STA) and long-term aging (LTA) of unmodified and modified bitumens were simulated using the rolling thin film oven (RTFO) and pressure aging vessel (PAV) tests respectively. The pull-off test was conducted using the universal testing machine (UTM). Stainless steel and granite substrates moulds were designed and fabricated for this purpose. Dry and wet conditions were simulated to evaluate the loss of bonding strength due to aging. Additionally, consistency tests, namely penetration test, softening point test, and viscosity test, were conducted on all binders. The activation energy (AE) for unaged and aged binders were also evaluated. The results for the consistency test; the pull-off test for stainless steel substrate; and the values for AE showed that the addition of the HNT decreased the effect of aging, which means that modified binders showed decreased temperature susceptibility and this is reflected in improved aging resistance. The result of the pull-off test on granite substrate showed that binders modified with HNT performed better under dry and wet conditions. It can be concluded that HNT is an anti-aging as well as anti-striping agent.

GAS PERMEABILITY MEASUREMENTS ON ASPHALT USIHO THE ELECTRODTNAMIC BALANCE

ABSTRACT A novel experimental method developed for the measurement of the transport properties such as the diffusion coefficient, D, solubility, S, and permeability, P, for oxygen Into asphalt materials using an electrodynamic balance Is described. Both imaged and aged rolling thin-film oven test (RTFOT) asphalt particle samples In the 12 to 62 pm size range were suspended contactless and weighed In the balance to measure D, S, and P In the temperature range 17°C to 66°C. Volatilization rate data were obtained from the particle mass measurements made prior to the start of the sorption experiments. Sorption curves obtained in this study for unweathered asphalt samples showed a non-Pickian, two-stage type sorption behavior indicating the possibility of an additional mechanism other than diffusion. Analogous behavior in sorption was observed for weathered samples

Approche méthodologique directe et continue du processus d'oxydation des bitumes par spectroscopie infrarouge à transformée de Fourier

( Direct continuous method for studying oxidation of bitumens by Fourier-transform infrared spectrometry). The method is based on the standard rolling thin-film oven test with oxidation in air at 163°C. A specially designed infrared cell is used. FTIR spectrometry provides spectral fingerprints which are characteristic for each bitumen.

A Study on Heat Deterioration of Asphalt by Thin Film Oven Test (Part 2)

The deterioration of Kuwait asphalt was studied by thin film oven test (TFO) and rolling thin film oven test (RTFO). The relationship between physical properties and chemical composition and that between penetration index (PI) and the peptization state of asphaltenes, and characteristics of deterioration in asphalt constituents were observed in an aging-process. The following results were obtained.1) It was shown that the relationship of asphaltene content vs. reciprocal of penetration was linear in case of TFO, but that the plot was broken at about 25wt% of asphaltene content in case of RTFO. On the other hand, the linear relationship between the extinction coefficient of carbonic band and reciprocal of penetration was shown on both TFO and RTFO.2) It was observed that penetration index decreased in the initial aging on both TFO and RTFO, while the state of peptization of asphaltenes increased. Therefore, the change of PI in the initial aging was mainly dependent on the change in the state of peptization of asphaltenes, but this relationship faild with the progress of deterioration.3) From the results of chromatographic fractionation for asphalt constituents aged at 163dC for 20hr by TFO and the IR spectra, it was found that 6.2wt% of the saturates were changed to aromatics, 12.3wt% of the resins to asphaltenes, and 95wt% of the asphaltenes to insoluble materials in benzene, respectively and that the changes in composition of the aromatics and resins were mainly dependent on the molecular weight, but in case of the saturates it was dependent on the functional group containing oxygen. Therefore, the saturates molecule oxidized by heat was fractionated to the aromatics.