Properties Of Bituminous Mixtures Research Articles

Engineering Properties of Bituminous Mixtures Blended with Second Reclaimed Asphalt Pavements (R2AP)

ABSTRACT Reclaimed asphalt pavements (RAP) have been called one of the most recycled materials in the world. Pavements mixed with RAP would be milled or excavated when they reach the end of service life. The reuse of RAP makes it as a second RAP, and is referred as R2AP in this study. R2AP was added at ten levels to hot-mix asphalt mixtures (HMA) with four different recycling agents in the laboratory. Adding 40% R2AP did not appear to alter the mixture properties dramatically. When the percentage was higher than 40%, the aged binder in R2AP created a significant change in the mixture properties. All the mixtures showed an increase in energy loss with an increase in R2AP percentages. The higher energy loss in the R2AP mixture indicated a higher possibility of moisture-induced damage. There should be a limit on percent R2AP that could be incorporated into HMA.

Evaluation of the laboratory prediction of surface properties of bituminous mixtures

An experimental and analytical investigation was carried out both in laboratory and in situ on wearing courses. The approach presented in this paper aims to predict the in situ density and surface properties of bituminous layers, during the phase of mix design in laboratory. Therefore, the main attempt of this study is to identify, amongst the commonly available laboratory equipments, the most adequate for producing specimens that, used for carrying out simple and reliable laboratory test, allow the prediction of the surface characteristics of the mixture as laid on site. This is done by comparing the data collected from an experimental site with those calculated from laboratory specimens compacted with the superpave gyratory compactor (SGC). Typical laboratory tests (such as the sand patch method and the skid test) as well as the surface data obtained with a laser profilometer have been considered for characterizing the properties of a standard Italian wearing course, laid in two different final thicknesses and produced with the most common raw materials, according to the currently used techniques for mixtures production and laying process for maintenance work. An evaluation of the SGC ability to represent the density and surface properties of the mixture once on site is then discussed.

The Properties of Bituminous Mixtures for Semi-Flexible Pavement

The Properties of Bituminous Mixtures for Semi-Flexible Pavement

Three-Dimensional Linear Behavior of Bituminous Materials: Experiments and Modeling

The linear viscoelastic properties of bituminous mixtures are used to design pavement structure. Usually, only complex moduli E* (complex Young modulus) or G* (complex shear modulus) characterizing the stiffness of the materials in one direction (1D) are measured by classical tests. In this paper, the three-dimensional (3D) behavior is investigated. The complex Poisson's ratio ( ν* ) is introduced. Its evolution with temperature and frequency is studied for a bitumen, a mastic, and a mix. Experimental results show that the time–temperature superposition principle is applicable in the 3D case. The same shift factor applies for E* and ν* . The Di Benedetto–Neifar model developed at Ecole Nationale des Travaux Publics de l’Etat to simulate so far the 1D thermo-elastoviscoplastic behavior of bituminous materials has been extended to simulate their 3D isotropic behavior. Calibration of the model and comparison between simulations in the linear viscoelastic domain and experimental data are proposed.

Aging Effect on Mechanical Characteristics of Bituminous Mixtures

Traditionally, asphalt concrete requirements are based on recipe specifications for bituminous mixtures; these specifications do not consider changes in the mechanical properties of materials over time. A considerable hardening of bitumen occurs with age, a characteristic that must be considered in the evaluation of bituminous materials. In asphalt concrete evaluation work, such as pavement design or end-product contracts, the age of asphalt materials may have a considerable impact on the outcome. This investigation was undertaken to aid the development of a performance specification that is based on the structural functional properties of asphalt concrete. Properties of asphalt concrete cores from various road sections were evaluated with respect to changes in stiffness and creep over several years, with an emphasis on hardening during the early life of the pavement. Relationships between mechanical properties of bituminous mixtures and age have been established. The results make it possible to take into account the effect of aging during pavement evaluation and during characterization of mixes with respect to aging properties. It was shown that stiffness modulus and creep deformation of bituminous layers can change significantly during the early life of the pavement and that this change should be considered in performance specifications and pavement analysis.

Aging Effect on Mechanical Characteristics of Bituminous Mixtures

Traditionally, asphalt concrete requirements are based on recipe specifications for bituminous mixtures; these specifications do not consider changes in the mechanical properties of materials over time. A considerable hardening of bitumen occurs with age, a characteristic that must be considered in the evaluation of bituminous materials. In asphalt concrete evaluation work, such as pavement design or end-product contracts, the age of asphalt materials may have a considerable impact on the outcome. This investigation was undertaken to aid the development of a performance specification that is based on the structural functional properties of asphalt concrete. Properties of asphalt concrete cores from various road sections were evaluated with respect to changes in stiffness and creep over several years, with an emphasis on hardening during the early life of the pavement. Relationships between mechanical properties of bituminous mixtures and age have been established. The results make it possible to take into...

Properties of bituminous mixtures at low temperatures and relations with binder characteristics

Within the framework of a partnership between the “Departement Genie Civil et Bâtiment” of the ENTPE, Eurovia and Appia, a research work including a large experimental campaign on the thermomechanical behavior of bituminous materials at low temperatures is proposed. The aim is to establish the links between the characteristics of the binder and the properties of bituminous mixes at low temperatures. Four different bitumens have been used with one type of aggregate and grading. The low temperature behavior of binders was evaluated with three fundamental tests: the complex modulus determination, the Bending Beam Rheometer and the tensile strength at a constant strain rate and constant temperatures. The thermomechanical behavior of bituminous mixes has been studied by performing complex modulus tests, measurements of the coefficient of thermal dilatation and contraction, tensile tests at constant temperatures and strain rates, and Thermal Stress Restrained Specimen Tests. The results are analyzed considering a rational approach. Some pertinent links between binders and mixes properties are established. Characteristics which are pertinent and discriminating enough with regard to the thermal cracking of bituminous mixes at low temperatures are presented.

Properties of bituminous mixtures at low temperatures and relations with binder characteristics

Properties of bituminous mixtures at low temperatures and relations with binder characteristics

Enrichment of Fine Mica Originating From Rock Aggregate Production and Its Influence on the Mechanical Properties of Bituminous Mixtures

Analyses of mica-bearing, crushed granitoid rocks revealed a significant enrichment of free mica in the fine fraction. Qualitative tests of bituminous mixtures with an increasing content of free mica in the fine fraction suggested a considerable deterioration of the mechanical properties of the asphalt mass. The negative influence of fine mica on the mechanical properties of the asphalt mixtures was most likely caused by the ability of mica to adsorb bitumen and to create zones of weakness. This phenomenon seemed to be linked to a preferred orientation (foliation) of the mica particles that was connected to the compaction of asphalt masses during the construction of the surface course. The threshold content at which the fine mica negatively influenced the quality of the bituminous mixtures was estimated to be 30–35 vol.%.

Physical and Mechanical Properties of Bituminous Mixtures Containing Oil Shales

Rutting of bituminous surfaces on the Jordanian highways is a recurring problem. Highway authorities are exploring the use of extracted shale oil and oil shale fillers, which are abundant in Jordan. The main objectives of this research are to investigate the rheological properties of shale oil binders (conventional binder with various percentages of shale oil), in comparison with a conventional binder, and to investigate the ability of mixes to resist deformation. The latter is done by considering three wearing course mixes containing three different samples of oil shale fillers--which contained three different oil percentages--together with a standard mixture containing limestone filler. The Marshall design method and the immersion wheel tracking machine were adopted. It was concluded that the shale oil binders displayed inconsistent physical properties and therefore should be treated before being used. The oil shale fillers have provided mixes with higher ability to resist deformation than the standard mix, as measured by the Marshall quotients and the wheel tracking machine. The higher the percentages of oil in the oil shale fillers, the lower the ability of the mixes to resist deformation.

Effects of Degree of Compaction on the Mechanical Properties of Bituminous Mixtures

Effects of Degree of Compaction on the Mechanical Properties of Bituminous Mixtures

Mechanical Properties of Bituminous Mixtures in a Loose State

Mechanical Properties of Bituminous Mixtures in a Loose State