Abstract

One of the elements that determine the durability of bridge structures is the bridge pavement. The durability of"br" bridge pavements depends on two main factors: traffic load and climatic conditions. Bridge deck surfaces might"br" exceptionally become exposed to extreme low and high temperature conditions. Stresses and strains in this type"br" of construction are different from those of the road surfaces located on the soil. Bituminous binders and asphalt"br" mixtures are thermoplastic components of waterproofing layers and surfacing. Their properties vary depending on"br" the temperature. This paper presents the laboratory test results of rheological properties of asphalt mixtures for"br" bridge pavements. The research plan included typically used asphalt mixtures - asphalt concrete (AC), stone mastic"br" asphalt (SMA) and mastic asphalt (MA). A new type of mixtures, stone mastic asphalt with high grit content SMAMA,"br" were also tested. Paper presents test procedure for determining the stiffness of asphalt mixtures on cylindrical"br" samples. Samples preparation and test method of direct tension–compression on cylindrical specimens (DTC-CY)"br" were discussed. The selected results of dynamic modulus and phase angle at different temperatures and varied"br" frequencies were presented. These parameters describe the visco-elastic properties which determine the durability"br" of bridge pavements. The results were presented as a leading curves, black curves and Cole-Cole graphs. A"br" comparison of the results of asphalt mixtures with the results of binder in dynamic shear rheometer DSR was"br" performed. The functional evaluation of the asphalt mixtures was extended for fatigue life test and rutting"br" resistance. The results of conducted research proved that the types of asphalt mixture affect the viscoelastic"br" properties and durability of bridge pavements.

Abstract

Dynamic penetration tests DPT have been routinely employed in the geotechnical characterization of the subsoil in different types of engineering projects. The evaluation of the results of these tests has been performed considering a limited number of parameters obtained in the field, so the definition of new parameters allows a more accurate evaluation of soil characteristics. The purpose of this paper is to present a methodology for the evaluation of the dynamic modulus (Ekd) based on the analysis of the dynamic force and velocity signals recorded in each hammer impact. Variable energy DPT tests were performed on Fontainebleau NE34 sand specimens in a K0 calibration chamber. For each hammer impact on the penetrometer, a decoupling and wave reconstruction method was applied to obtain the force and velocity signals at the cone-soil interface, which are analyzed in the frequency spectrum to obtain the Ekd modulus. The results show that it is possible to evaluate the dynamic modulus at different vertical loading conditions and independent of the impact energy level of the hammer on the penetrometer.

Abstract

The Metropolitan Area of Bucaramanga is located within one of the three seismic nests in the world and therefore presents a high seismic and geotechnical threat (INGEOMINAS, 2001), therefore certain zones, especially those with alluvial and colluvial deposits, have limitations for the development of infrastructure projects, unless a threat assessment is carried out that indicates otherwise or, in its absence, it is reduced to low levels with stabilization works. The thicknesses of these deposits vary from a few meters to two hundred meters and their definition and dynamic behavior (damping coefficient and terrain degradation curves), would allow analysis with special non-linear constitutive models to better understand their response to a possible earthquake and to ensure the stability of the structures and even an optimization based on a possible lower spectrum. A new two-tower housing project of up to 36 stories high is a perfect scenario to carry out a local seismic response study and perhaps transform the way future projects are designed. It should be noted that, given the acceptable stiffness and granular composition of the soils, it is difficult to take unaltered samples and the Colombian NSR-10 standard does not require local behavior studies and therefore its study has not been properly established. It is sought through geophysical tests and laboratory tests such as triaxial, resonant column and bender element to perform such characterization and to perform soil modeling that allows the calculation engineer to have the appropriate inputs for their analysis.