Browsing by Author "Laukkanen, Olli-Ville"

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Aging of bituminous binders in asphalt pavements and laboratory tests
(2018) Lu, Xiaohu; Soenen, Hilde; Laukkanen, Olli-Ville
A4 Artikkeli konferenssijulkaisussa
Aging of bituminous binders is one of the key factors affecting the performance and durability of asphalt pavements. To simulate binder aging in laboratory, a number of methods are available. In this paper, RTFOT (Rolling Thin-Film Oven Test), PAV (Pressure Aging Vessel) and RCAT (Rotating Cylinder Aging Test) using different aging times and temperatures were employed to age two straight-run bitumens and a styrene-butadiene-butadiene (SBS) polymer modified binder. For field aging, a number of asphalt pavements of different years in service were investigated. The binders (virgin, laboratory aged, and extracted from asphalt pavements) were evaluated by penetration and softening point tests, rheological measurements with a Dynamic Shear Rheometer (DSR), as well as chemical analyses using Fourier Transform Infrared Spectroscopy (FTIR) and Gel Permeation Chromatography (GPC). It was confirmed that the rheological changes upon laboratory aging and the formation of chemical functionalities were strongly temperature dependent. Great differences were found between the unmodified and SBS polymer modified binders in the rheological response upon aging. For the modified bitumen, different chemical reactions of the two components (bitumen and polymer) may compensate each other in some ways, making the binder less age-hardening and more durable. Apparently, the standardized PAV and RCAT simulate about 10 years of field aging for the unmodified bitumens when used in a dense asphalt surface layer, but for open graded mixes a longer PAV or RCAT aging time is necessary. However, for polymer modified bitumen the relationship between laboratory and field ageing when studying both mechanical and chemical compositional changes is less trivial.
Durability of Ring-Road II asphalt pavement - Phase I report on forensic analysis of Ring-Road II pavement distresses
(2013) Pellinen, Terhi; Makowska, Michalina; Olmos, Pablo; Laukkanen, Olli-Ville
School of Engineering | D4 Julkaistu kehittämis- tai tutkimusraportti tai -selvitys
This report presents findings from prematurely failed pavement of Ring-Road II (Kehä II) in Espoo, Finland. The road had excessive potholes, cracking, raveling and stripping only five years after construction. Core samples taken for this study revealed also that pavement layers were partially separated due to the lack of bonding. Research focus was to determine the causes of Stone Mastic Asphalt surface layer failure. Documentation of mix design, construction and material quality analysis, prior to and after construction, was compared to the samples collected from the road. Traditional quality assessment of the pavement by means of binder content and aggregate gradation analysis, air voids content, Indirect Tensile Strength and Stiffness, as well as binder tests including Penetration, Ring and Ball Softening Point and rheological characterization by Dynamic Shear Rheometer (DSR) were performed. Discrepancy was found in filler composition and additional analysis was made by applying standard analytical procedure of hydrochloric acid solubility. The findings were confirmed by means of Thermogravimetral Analysis (TGA), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), supported by BET-adsorption surface area measurements. The investigation revealed presence of fly ash that was apparently used for extending limestone filler during construction. It can be concluded that the main reason for the pavement failure was due to this substitution and the consequent problems that followed in the construction and thereafter in the pavement performance.
Dynaaminen virumistesti bitumin deformaatioherkkyyden testauksessa
(2013-05-10) Laukkanen, Olli-Ville
Insinööritieteiden korkeakoulu | Bachelor's thesis
An empirical constitutive model for complex glass-forming liquids using bitumen as a model material
(2018) Laukkanen, Olli-Ville; Winter, H. Henning; Soenen, Hilde; Seppälä, Jukka
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
While extensive research efforts have been devoted to understand the dynamics of chemically and structurally simple glass-forming liquids (SGFLs), the viscoelasticity of chemically and structurally complex glass-forming liquids (CGFLs) has received only little attention. This study explores the rheological properties of CGFLs in the vicinity of the glass transition. Bitumen is selected as the model material for CGFLs due to its extremely complex chemical composition and microstructure, fast physical aging and thermorheological simplicity, and abundant availability. A comprehensive rheological analysis reveals a significant broadening of the glass transition dynamics in bitumen as compared to SGFLs. In particular, the relaxation time spectrum of bitumen is characterized by a broad distribution of long relaxation modes. This observation leads to the development of a new constitutive equation, named the broadened power-law spectrum model. In this model, the wide distribution of long relaxation times is described by a power-law with positive exponent and a stretched exponential cut-off, with parameter β serving as a measure of the broadness of the distribution. This characteristic shape of the bitumen spectrum is attributed to the heterogeneous freezing of different molecular components of bitumen, i.e., to the coexistence of liquid and glassy micro-phases. Furthermore, as this type of heterogeneous glass transition behavior can be considered as a general feature of complex glass-forming systems, the broadened power-law spectrum model is expected to be valid for all types of CGFLs. Examples of the applicability of this model in various complex glass-forming systems are given.
From simple to complex glass-forming liquids: broadening of the glass transition as studied by shear rheology
(2017) Laukkanen, Olli-Ville; Winter, H. Henning; Soenen, Hilde; Seppälä, Jukka
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Low-temperature rheology of bitumen and its relationship with chemical and thermal properties
(2015-05-18) Laukkanen, Olli-Ville
Insinööritieteiden korkeakoulu | Master's thesis
The thermal cracking performance of asphalt pavements is largely governed by the properties of the bituminous binder, and thus the low-temperature rheological characterization of bitumen is of great importance. Recently, a novel testing technique has been developed for the measurement of the low-temperature rheological properties of bituminous materials. This testing technique, commonly referred to as the 4-mm DSR, uses a 4-mm parallel plate geometry on a dynamic shear rheometer (DSR) with radial instrument compliance corrections. However, very little data produced by using the 4-mm DSR technique is currently available in the literature. The primary objective of this study was to examine the low-temperature rheological characteristics of various unmodified bitumens by using the 4-mm DSR technique. In addition, the correlations of the chemical and thermal properties with the low-temperature rheology of bitumen were investigated. The secondary purpose of this thesis was to study physical aging in bitumen. The 4-mm DSR technique was used to test twenty-seven bitumen samples originating from various crude oil sources and refineries. The chemical properties of the bitumens were described in terms of their molecular weight properties, as measured by gel permeation chromatography (GPC), and aromatic properties, as measured by ultraviolet-visible spectroscopy (UV-vis), infrared spectroscopy (FT-IR) and refractive index (RI) techniques. The thermal properties of the studied bitumens, including the glass transition temperatures (Tg), were determined by differential scanning calorimetry (DSC). Both horizontal and vertical shifts were needed to produce smooth master curves in the vicinity of Tg. The temperature dependence of horizontal shift factors was shown to accurately follow the Kaelble-WLF equation in the temperature range of Tg-30 K to Tg+115 K. The calculated relaxation time spectra H(tau) evidenced a transition from small-scale molecular to large-scale cooperative relaxation processes when bitumen was cooled below its Tg. It was shown that the low-temperature rheological properties of bitumen can be fairly accurately predicted from the molecular weight and aromatic properties. Physical aging in bitumen was successfully analyzed by means of time-aging time superposition, and, based on the limited data available, equilibrium is attained in approximately 2-3 days at Tg. However, additional studies are needed to properly assess the effect of physical aging on the low-temperature rheological properties of various bitumens.
New approach for modeling polymer modified bitumens as polymer solutions: power-law scaling of rheological constants
(2017) Laukkanen, Olli-Ville; Winter, H. Henning; Soenen, Hilde; Seppälä, Jukka
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Rheology of complex glass-forming liquids
(2018) Laukkanen, Olli-Ville
School of Chemical Technology | Doctoral dissertation (article-based)
While the rheology of chemically and structurally simple glass-forming liquids (SGFLs) has been studied extensively in the literature, very little is known about the rheology of chemically and structurally complex glass-forming liquids (CGFLs). The aim of this thesis was to study the rheological properties of these CGFLs near and below the glass transition temperature (Tg). In addition, rheological characterization and analysis techniques were developed in support of this research. In the experimental part of this work, small-diameter parallel plate (SDPP) rheometry was introduced as a simple and accurate technique to measure the rheological properties of glass-forming liquids in shear. This measurement technique was applied to petroleum fluids that were chosen as model materials for CGFLs. In particular, bitumen exhibits a very broad viscoelastic glass transition in comparison to SGFLs. This is particularly accentuated in the broadening of the relaxation time spectrum at long times. Based on this observation, a new constitutive model – called the broadened power-law spectrum model – was proposed for CGFLs. This model was successfully used to describe the viscoelastic behavior of a series of petroleum fluids. The stretching parameter β of the broadened power-law spectrum model, which serves as a quantitative measure of the broadening of the relaxation time spectrum, was found to correlate with the width of the calorimetric glass transition region in a power-law fashion. The modification of bitumen with styrene-butadiene-styrene (SBS) block copolymer resulted in a distinct two-phase morphology. The morphological characteristics of SBS modified bitumen were shown to have a profound impact on the thermorheological behavior at low temperatures. In addition, special attention was paid to the temperature dependence of viscoelastic properties in the vicinity of Tg. Analytical expressions were derived for the dynamic fragility (m) and apparent activation energy (Ea) in terms of the parameters of the modified Kaelble equation, and it was observed that the linear Tg-dependences of m(Tg) and Ea(Tg) are unusually strong in bitumens in comparison to other classes of glass-forming liquids. It was demonstrated that time-resolved rheometry in combination with the time-aging time superposition principle is a powerful technique to monitor and analyze the time dependence of linear viscoelastic properties during physical aging. This technique successfully captured the effects of temperature, crystallinity and SBS polymer modification on the physical aging of bitumen.
Small-diameter parallel plate rheometry: a simple technique for measuring rheological properties of glass-forming liquids in shear
(2017) Laukkanen, Olli-Ville
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The rheological characterization of glass-forming liquids is challenging due to their extreme temperature dependence and high stiffness at low temperatures. This study focuses on the special precautions that need to be taken to accommodate high sample stiffness and torsional instrument compliance in shear rheological experiments. The measurement errors due to the instrument compliance can be avoided by employing small-diameter parallel plate (SDPP) rheometry in combination of numerical instrument compliance corrections. Measurements of that type demonstrate that accurate and reliable rheological data can be obtained by SDPP rheometry despite unusually small diameter-to-gap (d/h) ratios. Specimen preparation for SDPP requires special attention, but then experiments show excellent repeatability. Advantages and some current applications of SDPP rheometry are briefly reviewed. SDPP rheometry is seen as a simple and versatile way to measure rheological properties of glass-forming liquids especially near their glass transition temperature.
Strain accumulation in bituminous binders under repeated creep-recovery loading predicted from small-amplitude oscillatory shear (SAOS) experiments
(2018) Laukkanen, Olli-Ville; Winter, H. Henning
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The creep-recovery (CR) test starts out with a period of shearing at constant stress (creep) and is followed by a period of zero-shear stress where some of the accumulated shear strain gets reversed. Linear viscoelasticity (LVE) allows one to predict the strain response to repeated creep-recovery (RCR) loading from measured small-amplitude oscillatory shear (SAOS) data. Only the relaxation and retardation time spectra of a material need to be known and these can be determined from SAOS data. In an application of the Boltzmann superposition principle (BSP), the strain response to RCR loading can be obtained as a linear superposition of the strain response to many single creep-recovery tests. SAOS and RCR data were collected for several unmodified and modified bituminous binders, and the measured and predicted RCR responses were compared. Generally good agreement was found between the measured and predicted strain accumulation under RCR loading. However, in the case of modified binders, the strain accumulation was slightly overestimated (≤20% relative error) due to the insufficient SAOS information at long relaxation times. Our analysis also demonstrates that the evolution in the strain response under RCR loading, caused by incomplete recovery, can be reasonably well predicted by the presented methodology. It was also shown that the outlined modeling framework can be used, as a first approximation, to estimate the rutting resistance of bituminous binders by predicting the values of the Multiple Stress Creep Recovery (MSCR) test parameters.
Systematic broadening of the viscoelastic and calorimetric glass transitions in complex glass-forming liquids
(2018-03) Laukkanen, Olli-Ville; Winter, H. Henning; Soenen, Hilde; Seppälä, Jukka
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
In this experimental study, we explore the broadening of the glass transition in chemically and structurally complex glass-forming liquids (CGFLs) by means of thermal and rheological characterization techniques. Petroleum fluids with different levels of chemical and structural complexity are used as model materials. Thermal characterization by temperature-modulated differential scanning calorimetry (TMDSC) reveals a systematic increase in the width of the glass transition region ΔT g with increasing chemical and structural complexity. The broadening of the glass transition is also strongly reflected in the linear viscoelastic properties that are measured by small-diameter parallel plate rheometry. Most notably, this is observed as the broadening of the relaxation time spectrum at long times. The recently proposed broadened power-law spectrum model is used to describe the constitutive behavior of the investigated petroleum fluids. In this model, the stretching parameter β serves as a quantitative measure of the spectral broadening. A strong power-law correlation is found between ΔT g and β, manifesting a relationship between the broadness of the calorimetric and viscoelastic glass transition in CGFLs.