Morphology, rheology, and physical properties of polymer-modified asphalt binders

The mechanical properties of asphalt mixtures with Recycled Concrete Aggregates

This paper describes investigation into the change in complex modulus (norm and phase angle) during cyclic tests on bituminous mixtures. The change can be explained by four phenomena: nonlinearity, heating, thixotropy and fatigue. An experimental campaign has been performed at ENTPE laboratory in order to identify and quantify the first three phenomena. The analysis of the results reveals that the two reversible effects (heating and thixotropy) are very important and can not be ignored when interpreting fatigue tests. Nonlinearity, for the rather small strain level amplitudes considered in our experimental campaign (up to 122 μm/m), is also shown to be reversible. Heating is due to the viscous dissipated energy that heats the specimen. At the beginning of the test, temperature increase in the sample is shown to be proportional with the total dissipated energy. Thixotropy effect is quantified. In addition, it is shown that thixotropy effect can be modeled using an equivalent temperature increase.

Nonlinearity, Heating, Fatigue and Thixotropy during Cyclic Loading of Asphalt Mixtures

Although already known for a long time, hydrated lime (HL) attracted a strong interest as an asphalt additive during the 1970s in the USA, when moisture damage and frost became some of the most pressing pavement failure modes of the time. Given its extensive use in the past 40 years, HL is known to be more than a moisture damage additive: it is an “active filler” that also reduces the chemical ageing of the bitumen and stiffens the mastic more than a normal mineral filler above room temperature. These properties impact durability, and HL is now seen as an additive that increases asphalt mixture durability. This article is a literature review on the fundamentals of the effect of HL on asphalt mixtures. The reasons for it being so effective lie in the strong interactions between both the aggregate and the bitumen and a combination of four mechanisms, two on the aggregate and two on the bitumen. HL modifies the surface properties of the aggregate, allowing for the development of surface composition and rough...

https://www.tandfonline.com/doi/pdf/10.1080/14680629.2012.743669

The mechanisms of hydrated lime modification of asphalt mixtures: a state-of-the-art review

Modelling the linear viscoelastic rheological properties of bituminous binders

A large experimental campaign on the characterization of the linear viscoelastic behaviour of different bituminous materials was carried out. The goal was to establish the links between the linear viscoelastic properties (which are observed in the small strain domain) of binders and those of bituminous mixes. The linear viscoelastic behaviour of bituminous binders and mixes was studied by performing complex modulus tests at different temperatures and frequencies. A unique rheological model (called “2S2P1D model”) was developed for the modelling of linear viscoelastic properties of both bituminous binders and mixes. This model consists of a generalization of the Huet-Sayegh analogical model. Analyses on test data for five binders and different mastic and mix composition, show that the introduced model fits quite well the measurements. Finally, from our first results, a transformation that is independent of the introduced model allows the mix complex modulus to be predicted easily and efficiently f...

Linear viscoelastic behaviour of bituminous materials: From binders to mixes

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.

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

An experimental campaign has been performed at the ENTPE laboratory in order to measure the linear viscoelastic properties (shear complex modulus G*) of mastics with a specifically developed device (annular shear rheometer). Different fillers have been used to design mastics, among which a new type of filler only composed of ultrafine particles. The use of these ultrafine particles induces a significant increase in the complex modulus of mastics at high temperature in comparison to mastics with classical fillers. The potential for reinforcement of fillers is quantified by the complex reinforcement coefficient RM* introduced in this paper. The ultrafine particles have also been used in bituminous mixtures. As it is observed for mastics, an important increase of the modulus is observed at high temperature for the mixtures made with ultrafine filler. Finally, simulations of the linear viscoelastic behaviour of bituminous materials with 2S2P1D model developed at the ENTPE are proposed. Simulations fi...

Linear Viscoelastic Properties of Bituminous Materials Including New Products Made with Ultrafine Particles

Mastic, composed of bitumen and filler, is an intermediate material between bitumen and mix. It plays the true role of binder in the mix. An experimental campaign has been performed at the ENTPE/DGCB laboratory in order to measure the linear viscoelastic properties (at low strain level) of mastics with a specifically developed experimental device (annular shear rheometer). The effects of the filler characteristics (type, size, concentration, gradation) and aging of the binder on the complex shear modulus (G*) of mastics have been analyzed on a large range of temperatures (from -25°C to 80°C) and frequencies (0.03 Hz to 10 Hz). A significant change in behavior between bitumen and mastics with high filler content (> 40% vol.) is observed and quantified. The new reinforcement complex coefficient RA *, introduced in this paper, allows to show that the filler effect is important at high temperature and/or low frequency. The filler gradation (size and spread of grains size values) seems to have little influence on the viscoelastic properties of mastics. In addition, the effect of binder aging on the mastic behavior is quantified by the aging complex coefficient. It seems not to be influenced by the filler type and the filler gradation. A rheological model (2S2P1D) developed at the ENTPE/DGCB laboratory is used to simulate the experimental results for all the materials. Correlations between the constants of the model and constituents of the materials are underlined.

Linear Viscoelastic Properties of Bituminous Materials: from Binders to Mastics (With Discussion)

A new type of filler, composed of only ultrafine particles (silica fumes), has been used to design mastics and asphalt concretes. An experimental campaign on mastics and mixtures, performed at the ENTPE/DGCB laboratory, compares the effect of the ultrafine particles to that of "classical" fillers. The linear viscoelastic properties (shear complex modulus G*) of mastics have been measured with a specifically developed device (annular shear rheometer) presented in this paper. The potential for reinforcement of fillers is quantified by the complex reinforcement coefficient R*M introduced in this paper. The results show that the use of the ultrafine particles greatly increases the complex modulus of mastics at high temperature, in comparison to mastics made with classical fillers. In the low-temperature region, the complex modulus is little affected by the filler characteristics. The effect of ultrafine particles has also been analyzed for asphalt concretes, which have been tested using a tension compression ...

Brice Delaporte

Papers

Linear viscoelastic behaviour of bituminous materials: From binders to mixes

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

Linear Viscoelastic Properties of Bituminous Materials Including New Products Made with Ultrafine Particles

Linear Viscoelastic Properties of Bituminous Materials: from Binders to Mastics (With Discussion)

Effect of Ultrafine Particles on Linear Viscoelastic Properties of Mastics and Asphalt Concretes