Ludovit Zanzotto

The University of Calgary · Civil Engineering

The development of recycling technologies of asphalt pavements has encouraged industry to promote the use of modifying agents (rejuvenators and/or softeners) able to soften aged bitumen. In this paper, a new concept of physicochemical rejuvenation is described, by using a reactive surfactant (dodecenyl succinic anhydride, DSA). The results obtained...

Tornadoes are the most destructive winds created by nature. Sometimes tornadoes are strong enough to destroy most things in their path. These types of tornadoes are few compared to all tornadoes confirmed/reported. Currently, existing scales describe severity levels in terms of intensity/magnitude, and they are not sufficient to clearly distinguish...

Existing scales for natural disasters describe severity in terms of intensity. Intensity scales are not highly correlated with impact factors such as fatalities, injuries, homelessness, affected population, and cost of damage. The descriptive words for disasters are also not sufficient to clearly comprehend the real magnitude of severity as there i...

The impacts of two different groups of polymers on the mechanical and rheological properties in a hard base asphalt were investigated. One group was modified with a reactive polymer, Elvaloy® 4170, with or without polyphosphoric acid (PPA). The other group used in this study was styrene butadiene styrene (SBS) D1101, either crosslinked with sulfur...

Tornadoes, also called twisters, are the most destructive winds created by Mother Nature. Populations are most sensitive to disastrous events with high fatalities. The severity level of the most extreme tornado for which data is available can be categorized as Catastrophe Type I according to the fatality based disaster scale proposed by Wirasinghe...

Existing scales for natural disasters describe severity in terms of intensity. Intensity scales are not highly correlated with impact factors such as fatalities, injuries, homelessness, affected population, and cost of damage. The descriptive words for disasters are also not sufficient to clearly comprehend the real magnitude of severity as there i...

The analysis of transport network reliability under a natural disaster warning (e.g., impending tsunami) is a complex task, in part, due to the uncertainty of the time of the event occurrence at different locations. Different magnitudes and epicenters of earthquakes, as well as ocean bathymetry, will cause tsunami waves to have different arrival ti...

The creep and recovery of asphalt modified with Elvaloy 4170 and polyphosphoric acid were studied at low temperatures, by inductive phenomenological methods. Two models of the tensile compliance function were investigated. Both models were derived from the linear viscoelastic retardation spectra and successfully used for the description of the cree...

One of the basic material characteristics of solids is Poisson's ratio. Its exact knowledge, including its dependence on time, allows us to model the effect of load, with given boundary conditions, on the behavior of material under consideration. Poisson's ratio, or rather the relationship between the longitudinal and transverse strain, has an impo...

Five asphalt paving mixes prepared with different asphalt binders (one conventional, two oxidized, and two modified by styrene-butadien-styrene copolymer, 2% and 4% by weight) were studied in small amplitude oscillation and wheel tracking tests. The main focus of the study was to investigate these materials at a relatively high service temperature...

The effect of additions of organically modified clay and a sulfur-based compound on the technological, as well as rheological properties of a conventional asphalt that was modified by a linear styrene–butadiene–styrene block copolymer, was studied via three factors and five levels of statistical experiment. Blends were prepared with conventional ph...

This contribution deals with rheological modeling of Hot Mix Asphalt (HMA) tensile creep compliance. The properties of HMA are studied at reference temperature 58°C. The Maxwell, Gamma-stretch and Gamma-stretch 2 models are used to fit the data of tensile compliance D(t), in the studied material.

Sustainable pavement infrastructure with long service life and less maintenance and rehabilitation cost are preferred and hence the need and demand for high quality asphalt binders and mixes are increasing. This paper focused on the high temperature behavior of asphalt binders and mixes and the evaluation of rutting potential of these asphalt binde...

Repetitive creep and recovery tests in bituminous materials- asphalt and asphalt paving mix are studied at high service temperatures. The non-exponential- stretched exponential type of continuous retardation spectrum is defined and used for the calculation of creep compliance function in repetitive shear and tensile creep and recovery experiments a...

It has been known for some time that the current AASHTO M 320-05 specification does not address the true rutting potential of modified asphalt binders. The multi-stress creep recovery (MSCR) test was proposed by the United States Federal Highway Administration to replace the AASHTO M 320-05 high-temperature specification parameter and various SHRP+...

There has been interest in modifying asphalt with polyethylene materials, which are a major plastic waste substance, especially low-density polyethylene (LDPE). In this study, combinations of three low molecular weight polyethylene (PE) wax materials and three recycled LDPE materials were used as asphalt modifiers. The modified asphalts were studie...

Asphalt binders with the same high-temperature performance grade (PG 64-xx), but prepared by different methods to cover the spectrum of conventional, oxidized, and polymer and crumb rubber modified binders, were selected for the testing of the rutting potential of paving mixes with these asphalt binders. The rutting potential of the paving mixes wa...

Ternary systems, bitumen/ethylene-vinyl acetate (EVA)/organoclay, were prepared by two mixing methods (physical mixing and melt blending) and then studied in small amplitude oscillations, start-up of shear flow and repeated creep and recovery tests. The effect of mixing method and the role of two organoclays on the rheological properties of the stu...

Repeated creep and repeated load permanent deformation tests were performed on asphalt binders and mixes. The repeated creep test method was proposed as a new method for the evaluation of the ability of modified asphalt binders to maintain their elastic response; and the suitability of this test method for evaluation of asphalt pavements was studie...

The effect of the addition of two different organoclays as a third component in polymer modified asphalts has been investigated. Ternary mixtures were prepared by adding clay and poly(ethylene-co-vinylacetate) to the asphalt, either separately, or in the form of a premixed master batch. The performed characterizations allowed the determination of h...

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The viscoelastic characterization of asphalt binders was determined with repeated creep and recovery experiments. Four different commercial asphalt binders from western Canadian heavy crude oil sources, covering a wide spectrum (straight run, polymer-modified, and blown and blend binders), were used. The differences in the viscoelastic behavior of...

Asphalt binder is a mixture of many different types of molecules. At the molecular level, one can visualize the asphalt binder as a colloidal system with asphaltene molecules dispersed in oil with naphthene and polar aromatics. The functional groups of the asphaltene molecules are essential in keeping them dispersed as colloids. These polar functio...

The analysis of transport network reliability under a natural disaster warning (e.g. impending tsunami) is a complex task, in part due to the uncertainty of the time of the event-occurrence at different locations. Different magnitudes and epicentres of earthquakes will cause tsunami waves to have different arrival times and wave heights in differen...

Polymer modified asphalt (PMA) has been found to be quite effective in improving the rutting resistance and the low-temperature cracking resistance of paving asphalt binder. In the last few years, PMAs are evaluated and tested not only by the Superpave performance grading (PG) system, but also by the Superpave Plus tests such as elastic recovery an...

With concerns about the economy abounding and unpredictable oil prices constantly fluctuating, there have been efforts to save money on asphalt by taking harder asphalts such as recycled asphalt pavement (RAP) and softening them with rejuvenating agents. In addition to saving money, using renewable or recycled materials rather than crude oil-derive...

The chemical and rheological properties of two asphalts selected from different sources (Urals, Russia; Cold Lake, Canada) were investigated. Analyses of chemical (elemental composition, fractional composition, molecular weights) and physical properties (complex viscosity, loss tangent, shear compliance) were performed on all original and aged (rol...

SUMMARY The effect of the addition of clay as a third component in polymer modified asphalts has been investigated. After a preliminary investigation on the binary asphalt/clay and polymer/clay blends, the tertiary blends were prepared by adding the clay and polymer to the asphalt, either separately or in the form of a premixed master batch. Interc...

The effect of thermal stresses and relaxation on the physical hardening of four asphalt binders was studied. The effect of thermal stress was evaluated by the time-storage time superposition (tts). It was found that the hardening took place in the pre-stressed samples; however, in the early stage of the experiment when the stresses were high, the h...

One of the distress modes of asphalt pavements is the rutting that occurs at high operating temperatures, and it is believed that the accumulated strain in asphalt binder is mainly responsible for the rutting. The asphalt industry has tried to use the parameter 1/J″ as the specification parameter for the determination of the susceptibility of aspha...

Relaxation and retardation spectra are often used to describe the linear viscoelastic properties of polymer melts, asphalts, and other viscoelastic materials, since the spectra contain sufficient information from which other linear material functions can be easily calculated. The applicability of these functions strongly depends on the range of fr...

At low temperatures, some asphalt binders are known to harden significantly with time. This process is commonly referred to as physical hardening; and, if neglected during testing, it may lead to overestimation of asphalt binder performance at low temperatures. Modulated differential scanning calorimetry (MDSC) and dynamic mechanical analysis (DMA)...

The effect of isothermal storage at −20°C on the glass transition temperature and enthalpy relaxation in five asphalt binders was determined by modulated differential scanning calorimetry. It was found that the glass transition temperature and enthalpy relaxation increased linearly with the logarithm of the storage time suggesting isothermal change...

The viability of used lubricating oil as an asphalt modifier was studied, with the enhancement of the low-temperature grade as the specific goal. Used oil modification was found to improve the Superpave low-temperature performance grade (PG), but at the expense of the high-temperature PG grade. When evaluated according to the Superpave MP1 specific...

Major aspects of the glass transition of asphalt binders are described and an extensive literature review of the phenomenon and its relation to chemical composition is presented. The glass transition of asphalt binders was studied by modulated differential scanning calorimetry and also via dynamic mechanical analysis. A certain analogy between the...

The aging behavior and sensitivity of two asphalts from different sources (Ural, Russia and Cold Lake, Canada)were studied. The rolling thin film oven test (RTFOT) and pressure aging vessel (PAV) were used to simulate theoxidative aging. Both asphalts were separated into fractions using the ASTM D 4124-01 (Corbett) separationmethod. The elemental a...

Rutting in asphalt pavement is a major concern in pavement engineering. There are various factors affecting the rutting in the asphalt surface of pavement. Some of these influences are the quality of the asphalt binder, the aggregate properties, mix design, and construction methods. Several conventional and modified asphalt binders were investigate...

In our study, the low-temperature properties of two asphalts of different origins (Urals, Russia; Cold Lake, Canada) and the same high-temperature performance grade were evaluated as samples were kept at low temperatures for an extended period of time. The effect of oxidative aging (RTFOT - rolling thin film oven test, PAV - pressurized aging vesse...

The viscoelastic properties of some binders change significantly with time at low temperatures. The binder usually stiffens over an extended period of time, even if maintained at a constant temperature. Therefore, the ability of the binder to relax the developed thermal stresses decreases with the time spent in a cold environment. At a certain poin...

Waste tire crumb rubber materials (CRM) were used to modify paving asphalts. The mixing time, hot-storage stability, Superpave grades, pumping and handling properties, phase separation tests, and repeated creep properties of the modified asphalts were studied using base asphalts of different hardness. Applying the Long-Term Pavement Performance (LT...

The viscoelastic nonlinear behavior of several base and polymer modified asphalts (PMA) has been studied in step-strain experiments. The polymers were poly(styrene-b-butadiene-b-styrene), poly(styrene-b-ethylene-co-butylene-b-styrene), poly(ethylene-r-vinylacetate) copolymers, and a linear low density poly(ethylene), which were chosen as representa...

Nowadays, asphalt cement is frequently modified by blending it with various polymers in order to obtain a material with improved engineering properties. In number of studies it has been shown that ethylene-vinyl-acetate (EVA) and styrene-butadiene-styrene (SBS) copolymers can enhance the rheological properties of conventional asphalt at relatively...

The aim of this work was the comparison of estimated zero-shear viscosity (ZSV) from both parts of the creep and recovery curve with directly measured ZSV, for asphalt modified with different amounts of radial styrene–butadiene–styrene (SBS) copolymer. Various time durations of creep and recovery were examined. The impact of waiting time between te...

A dynamic creep test was proposed as a new method for evaluating the ability of modified asphalt binders to maintain their elastic response. The test was readily proposed to evaluate the resistance to rutting of asphalt pavements. The authors are reporting the analysis of results of the dynamic creep test on several conventional and oxidized asphal...

Glass transition is one of the most important factors that determine the viscoelastic and low temperature properties of asphalt cement. The transition from rubbery into glassy state is accompanied by a sudden change in mechanical and thermodynamic properties of asphalt. During the glass transition the asphalt cement becomes extremely stiff and loos...

Some asphalt binders are known to stiffen significantly if maintained at low temperatures for an extended period of time. This process is commonly recognized as physical aging or hardening. The influence of thermal history on the glass transition of several asphalt binders was studied using modulated differential scanning calorimetry. A testing pro...

The inadequacy of the Superpave high temperature specification parameter, G*/sin δ, to correctly grade the superior field performance of modified asphalt binders has been demonstrated by several researchers. A new parameter that is blind to modification type and is performance based is now needed. As a replacement for the existing high temperature...

The mechanical response of soft base asphalt modified by tire crumb rubber material (CRM) was studied. Materials were investigated in three deformation modes. Small amplitude shear oscillations yielded the linear viscoelastic characterization of the studied materials. Steady shear experiments revealed the shear rate dependent viscosity functions. T...

The use of polymer modified asphalts for waterproofing and in road pavement has been continually increasing worldwide, because a relatively small quantity of added polymer can significantly enhance performance and durability. The knowledge of the morphological structure of such materials is still incomplete and controversial, mainly because of the...

Several polyethylene and polyethylene-based copolymers were used to modify a 70/100 penetration grade asphalt from vacuum distillation. The morphological and storage stability analyses showed that, in all cases, the obtained materials were strongly biphasic and tended to separate into polymer-rich and asphalt-rich phases. However, among the tested...

Historically, Maxwell was probably the first one who recognized the importance of time scales for understanding the mechanical response of asphalt. In instantaneous response asphalt behaves as an elastic, solid-like material, on the other hand its long time response is that of a viscous, fluid-like material. In the linear viscoelastic region asphal...

Startup flow of asphalt modified by styrene-butadiene-styrene and ethylene-vinyl acetate copolymer is studied at temperature T=60°C. It is shown that the base asphalt and blends with a low content of polymer (2% by weight) behave as linear viscoelastic materials. With increasing concentrations of polymer, the behaviour of the studied blends is nonl...

In our previous direct tension test (DTT) studies, SBS polymer modification was found to increase the failure stress values with increasing polymer levels, The predicted critical cracking temperatures (Tcritical) in Superpave MPla specification were found to be 3 to 6°C lower than the bending beam rheometer (BBR) low temperature parameter according...

The aim of this article is the comparison of flow properties of base and polymer-modified asphalts in different experimental modes. Various concentrations of polymers were added to base asphalt. Effect of the modification was observed and peculiar behaviour (noticed especially in steady state measurements) was modeled. When polymer-modified asphalt...

Asphalt is known to be a colloidal suspension in which asphaltenes are covered by a stabilizing phase of polar resins and form complex micelles that are dispersed in the oily maltenic phase. In order to enhance its mechanical properties (e.g., in road paving), asphalts are often loaded with polymeric materials, thereby obtaining blends that can hav...

The viscosity functions of several polymer-modified asphalts (PMAs) were studied at different temperatures in steady-state rate sweep tests. The materials were obtained by mixing different base asphalts with either styrene-butadiene-styrene (SBS), ethylene-vinylacetate (EVA) or reactive ethylene terpolymers (RET). The first two polymers form a phys...

Two modifiers, SBS and EVA, were used for the asphalt modification in this study. The BBR and DTT were used to investigate the low temperature creep and fracture properties of the asphalt binders, and the IDT was used for the low temperature creep and fracture characteristics of asphalt mixes. The modification with SBS was found more effective than...

Polymer modified asphalt is an highly temperature sensitive material. To obtain the master curves of dynamic material functions, for this material, it is necessary to perform the testing over the temperature interval from - 30°C to at least 90°C. Since in this temperature range the polymer modified asphalt undergoes the transition from a glass-like...

Asphalt is a multidisperse micellar system with rheological behavior resembling that of a low-molecular-weight polymer. Nowadays, asphalt is frequently modified by blending it with various polymers. Such modified asphalt has rheological properties that differ from the properties of the base asphalt. It is quite common to study asphalt in dynamic ex...

One regular and one polymer modified asphalt were studied in simple shear flow and in harmonic electromagnetic field. Viscosity function and complex dielectric permittivity for both asphalts were compared. The time-temperature superposition of rheological and dielectric data yields identical (or almost identical) shifting factors. A close relations...

The possibility of using commercial rheometers for comprehensive testing of asphalt binders, asphalt mastics, and hot-mix asphalts (HMA) is explored. Samples of one polymer-modified asphalt, its mix with fine mineral filler (mastic), and one HMA prepared with the same modified asphalt as binders were tested in the dynamic shear rheometer (DSR) and...

The low-temperature performance grades of air blown asphalts and straight run asphalts from two different crude oil sources were studied using the Superpave MP1 and MP1a specification. The DTT secant modulus and failure energy at Tcritical were also analyzed and compared.

Conventional and polymer modified asphalts (PMA) are routinely tested in small amplitude oscillations. It is probable that asphalt as a part of paving mixture is exposed to large deformations. Hence a better understanding of asphalt behavior in large amplitude oscillations (LAOS) is needed. LAOS experimental results for a base asphalt and its blend...

The introduction of the Superpave((R)) asphalt binder specification provided the asphalt industry with a useful guideline for choosing appropriate materials to meet the requirements of a specific climate. Acid, alkaline, and polymer modification are just some of the ways to modify asphalt to meet the Superpave specification. The direct tension test...

In this note rheological properties of two different polymer modified asphalts (PMA) are compared. PMAs were prepared from two different base asphalts, a soft one (200/300 Pen grade) and a hard one (70/100 Pen grade), by addition of 4% by weight of radial SBS as modifier. Dynamic mechanical properties were determined in a wide temperature range for...

During Superpave direct tension testing (DTT) of asphalt binders, the failure stress and failure strain values were found to depend strongly on the molecules of asphalt in the DTT mold forming a stable network. An asphalt specimen in which molecules have formed a network with aligned dipole moments has a higher DTT failure stress value, A sample pr...

Costly deterioration of many roads and highways paved with asphalt generates a growing interest in polymer modified asphalts (PMA). Although asphalt represents only a fraction of asphalt paving mix, it is believed that it has a significant effect on the thermomechanical properties of asphalt pavements. Currently there is no consensus on the type of...

Shear vibrations in conventional and polymer-modified asphalt binders are examined. Using dynamic compliances instead of moduli, viscous deformation effects can be separated from total deformation and the modified dynamic loss compliance and modified loss tangent functions can be defined. These two material functions appear to be more sensitive tha...

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Dielectric permittivity and mechanical complex compliance of regular asphalts, at T = 323 K, are studied. Both the loss compliance and the loss of permittivity functions can be decomposed into two parts. The first part represents the viscous deformation and the ohmic conductivity, respectively. The second part then describes a "pure" response of th...

Dynamic material functions are among the most sensitive tools for determining the molecular weight distribution of rheologically complex systems. The phase angle of the complex modulus especially is sensitive to the molecular weight of the studied material; it can therefore be used as the input to the inverse problem of determining the molecular we...

In past decades polymer-modified asphalts have become commonly used materials for the construction of high-quality flexible pavement. Regardless of the commercial importance of these "modified asphalts," little is known about the mechanisms of polymer-asphalt interaction, and polymer-asphalt production is purely empirically based. A better understa...

Stress relaxation after a nonsteady uniaxial extension with finite strain of crack sealants is studied at low temperatures. The integral constitutive model is used and the first normal stress difference, obtained experimentally, is modelled. It was found that the stretched exponential relaxation occurs in the tested materials. The stress growth and...

The phase angle of the complex modulus is sensitive to the molecular weight of the studied material; it can therefore be used as the input to the inverse problem of determining the molecular weight from this important dynamic material function. Molecular weight distributions of several regular asphalts are calculated using the phase angle and compa...

The master curves of dynamic moduli, obtained by using a temperature(θ)-frequency(ω) superposition principle, are commonly available for the reduced frequencies, ω’ = ωa T(θ), over 10 to 15 decimal orders of magnitude. For fitting such an extended experimental information, Winter et al. (1993) suggest to use the generalized Maxwell model. As many a...

The stretched exponential relaxation modulus of regular and polymer modified asphalts is studied. It is shown that this relaxation function can generate the dynamic functions of these materials very well on any finite interval of the reduced frequencies (master curves). By continuation one can, in principle, cover the whole region of master curves...

Asphalt (or bitumen) is one of the earliest construction materials used by mankind. However, despite the long history of its use and the important role it plays at the present time, in the construction of pavements, the composition and especially the structure of asphalt is still not fully understood. It is generally believed that asphalt is a mult...

Rheological methods of characterization of regular and modified bitumens are studied. The fractional model of a complex modulus is inverted to generate the corresponding molecular weight distribution. A possibility to obtain more information about the structure of bitumens via the phase angle is investigated. The problem of a calibration equation i...

Scrap tires in three forms - crumb rubber 60 minus mesh, crumb rubber 20 minus mesh, and buffed rubber - were subjected to deporymerization and devulcanization by applying heat, high shear, and a combination of both. Different reaction temperature and times of reaction were applied. The reaction products were submitted to the testing of rheological...

A simple model of the complex modulus, based on the general principles for a linear response function, is presented. The model represents a generalization of the Maxwell model and it is indicated that the model well describes a relatively broad group of regular and modified asphalts. A discrete spectrum of no more than 10 relaxation times is obtain...

A simple model of the complex modulus, based on the general principles for a linear response function, is presented. The model represents a generalization of the Maxwell model and it is indicated that the model well describes a relatively broad group of regular and modified asphalts. A discrete spectrum of no more than 10 relaxation times is obtain...

Scrap tires in three forms—crumb rubber 60 minus mesh, crumb rubber 20 minus mesh, and buffed rubber—were subjected to depolymerization and devulcanization by applying heat, high shear, and a combination of both. Different reaction temperatures and times of reaction were applied. The reaction products were submitted to the testing of rheological pr...

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In recent years, a considerable effort has been made to develop a new generation of asphaltic materials based on a combination of polymers and asphalts. Regular and polymer-modified asphalts are studied via fractional relaxation processes, represented here by a fractional rational form of the complex modulus, G *. Basic properties of this complex m...

No direct link has been established between the basic nitrogen components of hydrocracked residues and the increase in anti-stripping properties of distillation residues containing them. Thus, it is the intent of this report to show that a correlation exists between the basic nitrogen components of hydrocracked residues and the anti-stripping prope...

The procedure of Hastings, for the spectrophotometric determination of cyclic and aliphatic sulphides, has been modified to increase its accuracy and reproducibility. The sensitivity of the method has been increased 32% by maximizing the reagent concentrations. Reproducibility has been calculated as better than 3% relative for crude oil samples. Th...