Papers by Keyword: Dynamic Modulus

Abstract: This paper has studied the mechanical properties (freeze-thaw splitting strength, and dynamic modulus) and road performance (dynamic creep and fatigue life) of the asphalt mixture under the freeze-thaw circle test, and made the quantitative analysis of the influence on the material performance under freeze-thaw circle test.

Abstract: This paper used the design method of EME high modulus HMA from France to carry out the mix design of EME2(0/14) HMA, and carried out Duriez test, HWTD, dynamic modulus test and low temperature bending test. The test result showed that this kind of HMA had excellent water resistance, high temperature rutting resistance, high dynamic modulus and low temperature cracking resistance. This EME high modulus HMA was applied in the test road on Qing Lin expressway.

Abstract: The portable falling weight deflectometer (PFWD) test, bearing plate test, beckman beam test, and compaction test were carried out in this study. The relation of dynamic modulus and static modulus, dynamic modulus and deflection, dynamic modulus and compaction ratio, dynamic modulus and water content (consistency) was built. It turns out that there are good power function regression relationship between dynamic modulus and static modulus, dynamic modulus and deflection, dynamic modulus and compaction ratio, dynamic modulus and water content and consistency. Key words: red sandstone; dynamic modulus; resilient modulus; deflection; compaction ratio; water content

Abstract: This work describes the anelastic behaviour of human dentin in the temperature range from 100 K to 673 K. Human molars, extracted from individuals (males 55-70 years old) as part of their dental treatment, were cut to obtain bar-shaped samples for mechanical spectroscopy (MS) experiments. The results are presented and discussed in two parts referring to experiments above and below room temperature.

Abstract: The objective of this study is to predict the asphalt mixture dynamic modulus using the viscoelastic properties of asphalt mortar. The dynamic viscoelastic characteristics of asphalt mortar and asphalt mixture are tested at different temperatures and loading frequencies using dynamic shear rheometer, such as storage modulus, loss modulus and phase angle. The complex modulus of asphalt mortar, volume parameters and Hirsch model were used to predict complex modulus of asphalt mixture. The experimental measurements of dynamic modulus were employed to compare with the predictions. The result showed this method can predict complex modulus of asphalt mixture very well.

Abstract: In this paper, Button rock asphalt particle was directly added into hot asphalt mixture (HMA) to produced high modulus asphalt mixture (HMAM). In order to evaluate the performance properties of HMAM with BRA, dynamic compressive complex modulus (E*) test, rutting test and moisture resistance test were used to investigate HMAM with BRA and HMA with SBS modifier. Test results indicate BRA can greatly improve dynamic E*and rutting resistance of HMA compared with SBS modified asphalt mixture. Moisture resistance ability of HMAM with BRA has the same level with SBS modified asphalt mixture. Therefore, BRA particle can be used to produce HMAM, which have more superior performance properties than SBS asphalt modifier.

Abstract: Based on the definition of fractional derivative, the paper proposed a unique new idea to describe the viscoelastic property of asphalt mixture with fractional calculus. According to the SPT (Simple Performance Tests) test results, the dynamic modulus and phase angle of asphalt mixture were determined. The result of the test was fitted with the classical Kelvin model, the Maxwell model, the solid model with three elements, respectively. It showed that the classical viscoelastic model did not simulate the dynamic mechanical properties of asphalt mixture properly. Since the existing constitutive relation cannot describe well the dynamic viscoelastic properties of asphalt mixture, the fractional derivative viscoelastic model with three elements was adopted and its fitting effect analyzed. The result shown a good fitting for the fractional derivative viscoelastic model with three elements, and a few test parameters were required to build the mode. In addition, these simulating parameters were significant in physics. The order  of the fractional derivative has good correlation with the phase angle, incarnating the viscoelastic proportion of asphalt mixture. So the fractional derivative viscoelastic model with three elements can accurately describe the dynamic mechanical properties of asphalt mixture.

Abstract: The work describes the anelastic behaviour of human dentin below room temperature. Human molars, extracted from individuals as part of their dental treatment, were cut to obtain bar-shaped samples for mechanical spectroscopy (MS) experiments. Repeated cooling-heating cycles in the range 300-100 K have been carried out on the same samples. In the cooling stage of the first cycle Q^-1 exhibits a very broad maximum due to a series of phase transformations involving water present in the pores, in the interstices between fibres, between fibrils and inside collagen triple helix. The formation of ice I_h produces permanent damages to the dentin structure (rupture of fibres and fibrils) leading to a decrease of maximum intensity in the following cycles. In the heating stage of all the cycles two maxima, M1 and M2, have been observed around 155 K and 178 K. M1 is due to the transformation of low-density amorphous (LDA) ice into ice I_C while M2 to that of ice I_C to ice I_h. Above 200 K, Q^-1 progressively increases with lower damping values in the cycles after the first one. Dehydrated samples do not exhibit the aforesaid anelastic phenomena confirming that their origin is connected to water and its transformations.

Abstract: Liquid Pb–Bi eutectic alloy has been selected as coolant and neutron spallation source for the development of MYRRHA, an accelerator driven system. The alloy has been characterized in liquid state from melting (125 °C) to 650 °C by mechanical spectroscopy. Experiments have been carried out using hollow reeds of austenitic stainless steel filled with the Pb-Bi alloy and sealed at the extremities. From 350 °C to 520 °C modulus shows a remarkable drop accompanied by a broad internal friction maximum. In the same temperature range radial distribution functions, determined from X-ray diffraction patterns, evidenced variations of the mean distance between the 1st nearest neighbour atoms. The anelastic phenomena have been attributed to a structural re-arrangement of liquid metal. For comparison, other alloys of the Pb-Bi system with hypo-eutectic composition have been investigated.

Abstract: Mechanical Spectroscopy provides information on microstructural features of materials not obtained by other techniques. In general, it is used for investigating physical phenomena, however it can be very useful also for solving problems related to industrial processes. This work describes and discusses some applications of metallurgical interest.