Maria J. Sulewska

Dynamic CBR Test to Assess the Soil Compaction

Earth structures require appropriate soil compaction, commonly assessed using the Proctor methods. In the case of cohesive soil and fly ash, whose permeability and mechanical properties depend on moisture content at compaction, compaction degree (% of maximum compaction) should not be the only parameter of estimation of soil compaction. Therefore, for such materials the California Bearing Ratio (CBR) could be used as a method of compaction assessment and an indicator of soil bearing capacity. Another and much more efficient method for the compaction control is the dynamic CBR (CBRd). This methodology is conducted by using a loading system employing a light falling weight deflectometer (LFWD), consisting of a falling weight to produce a defined force pulse on the CBR piston. In this paper, the CBR research was done for both static (classic) and dynamic methods on fly ash specimens without soaking them to replicate field conditions. A force of 2.44u2009kPa was applied to all specimens subjected to penetrations. Due to the speed of research execution of the dynamic CBR test, it could be used for running compaction control during embankment erection. Test results obtained from the tests on fly ash revealed that dynamic CBR could be recommended in the cases of embedded fine-grained soil with moisture contents insignificantly greater or less than optimum water content.

Spectral method as a tool to examine microtextures of quartz sand-sized grains

Well-rounded grains extracted from aeolian and subaqueous environments were analysed to determine a quantitative parameter describing the microtopographic surface properties of sand-sized quartz grains, expressed as a degree of smoothness or as an inverse roughness. To this end, the spectral method was used to calculate their fractal dimension values. Fractal characteristics and spectral fractal dimension (DS) were determined for a scanning electron microscope (SEM) image (560u202f×u202f560 pixels) obtained for each study grain. This parameter, (DS), describes the complexity of objects, which means that the higher its value, the more complicated the analysed grains are in terms of exterior roughness and surface microirregularities. The obtained results indicate that values of the parameter (DS) were higher for all aeolian grains compared to grains from either low- or high-energy subaqueous environments. This difference in results is attributed to the presence of microirregularities on the surface of aeolian grains, microtextures forms such as mechanically upturned. This parameter value increases as the energy of the aeolian environment increases. Values of (DS) for subaqueous environments grains correlated with the frequency of microtextures that resulted from high-energy grain-to-grain collisions (e.g., V-shaped percussion cracks), or from the chemical etching of the grain surface (e.g., solution pits, solution crevasses)-the higher the frequency of either collision or chemical-etching microtextures, the higher the value of the fractal dimension (DS). Thus, it has been demonstrated that fractal analysis can serve as a useful tool to discriminate between the analysed sedimentary environments, to assess a depositional systems kinetic energy, and to compare the intensity of chemical weathering.

Analysis of the results of empirical research and surveys of perceived indoor temperature depending on gender and seasons

The indoor thermal condition tests were conducted as real and declared by the respondents. The tests were carried out in the laboratory room in Bialystok. The object is a detached, two-storey building with a cellar. The tests were carried out from February to May 2015. In 1xa0week, on average, ten measurement series were carried out. During one experiment series, there were between 10 and 15 students present in the room. The aim of the publication is to analyze the results of declared perceived temperature tests in the room depending on the gender, the season and indoor and outdoor temperature conditions. On the basis of statistical analysis of the test results, it was found that in the analyzed age group, the perceived temperature declared in the room is not affected by the respondent’s gender. The conclusion is that the temperature sensations of young (and probably healthy) people who do not do physical work are similar, regardless of gender. Differences between the average perceived temperature in the room, declared by all respondents in winter and declared in spring are statistically significant. The indoor perceived temperature declared in the winter is almost constant and does not depend on the temperature of the perceived temperature of outdoor air.

Application of Fractal Geometry in the Evaluation of Surface Microtexture of Soil Particles

The shape of particles building the solid phase of soils is an important factor influencing soil behaviour. Three parameters defining the characteristics of particle shape: roundness, angularity and texture are the most commonly analyzed. The most difficult issue is texture determination due to its complex nature. Quantitative evaluation of this parameter creates serious problems, however, is not impossible. A new mathematical tool, such as fractal geometry, may be helpful. Through the use of power law, fractal analysis allows to designate fractal dimension that specifies the complexity of the tested object.

Comparison of Methods Determining the Angularity of Aggregate Particles

Particle shape raises more interest among geologists than among engineering geotechnical staff. It is commonly accepted that particle shape is the result of geological processes, such as transportation and sedimentation, and depends on many factors, such as mineral composition or structure and texture of the host rock. The influence of particle shape on the geotechnical properties of soil has been widely discussed in literature from the early 1900-ties, e.g. by Wadell [3], Riley [16], Pentland [6] and other scientists, who proposed their own definitions and methods of determining particle roundness and angularity. Finally, it has been decided that particle shape should be defined by three independent parameters [2]: roundness, reflecting the general shape of the particle in comparison to a sphere; angularity, describing changes in roundness in the corners of the studied particle; and microtexture, reflecting the complexity of the particle surface in micro scale; this parameter is also referred to as micromorphology. These three parameters describe particle shape at various magnifications and allow obtaining all important data on this feature. This report is focused on a review and analysis of the analytical methods determining particle angularity, and is an attempt to establish an optimal definition of determining particle angularity in road aggregates. We present selected definitions used to determine angularity, worked out by different authors over the years as an attempt to find the best analytical method of describing angularity.

Comparison of Methods Determining Particle Sphericity

Definition and studies on the shape of various bodies are an interdisciplinary issue, raising wide interest among scientists. In geology and geotechnics the studies refer to features related to the shape of soil and rock particles, especially of those used for practical purposes. Due to the complex shape of particles, its three components have been distinguished: sphericity, angularity and surface microtexture. Sphericity usually determines the degree of similarity of a given particle to a sphere, whereas defined as a form refers to the general shape of the particle [3]. Particle shape and parameters that characterise it have not been unequivocally defined and normalised, resulting in a large number of definitions and ways of their determination. An extensive paper presenting the definitions used to describe shape parameters has been presented by Szerakowska [13]. This paper is focused on the comparison of analytical methods and an attempt to select the most optimal method for determining sphericity of particles in construction and road aggregates.