No abstract

Heat islands are areas that have higher air temperatures than their surroundings. It has been proven that the use of certain types of pavement surface materials contributes to the occurrence of heat islands. The heat island effect is dominant in urban areas, mainly in city centres. To identify potentially favourable pavement surface materials that are suitable for the use on surfaces in urban areas, an extensive analysis of in-place material temperatures was conducted in the city centre of Rijeka (Croatia) during the summer of 2011 and 2012. The measurements included temperatures of pavement surfaces made of asphalt, concrete and stone. The analysis results identified local materials whose use help to reduce or mitigate the effect of additional heating in the urban environment caused by emission of heat from pavement surfaces. In terms of additional heating of urbanized areas, asphalt has proven to be significantly less favourable than other analysed materials. In addition to the materials selected for the use in wearing courses, their characteristics and the microclimates of the locations where they will be placed must be taken into consideration. Among the standard paving materials, in terms of heating and temperature, concrete is more favourable than asphalt because the differences between concrete surface temperatures and air temperatures are significantly smaller than between asphalt surface temperatures and air temperatures. Stone surfaces have proven to be the most favourable. The analysis results presented can be used to establish clear guidelines for using specific materials under specific conditions.

Image analysis methods are recently in use for asphalt pavement surface texture characterization and analysis in terms of pavement friction performance assesment. These methods enable more detailed description of texture properties at both micro and macro texture levels which are important for friction realization as they result in a digital representation of pavement surface. In comparison to the traditional methods for texture characterization which result in one characteristic texture parameter, methods that are based on digital image analysis can yield more texture parameters describing both profile and spatial characteristics of inspected surface texture. Previous application of image analysis methods for pavement texture characterization showed that pavement texture and friction relationship could be described more thoroughly by including texture parameters other than standard mean texture depth and mean profile depth derived from traditional measuring procedures. The possibility of texture data acquisition by means of digital images that can be further processed and exploited for creation of a 3D digital pavement surface model is presented in this paper. A research was performed on selected pavements in use where orthographic photogrammetry method was applied for texture data acquisition. Images were used for creation of a 3D pavement surface model defined as a dense point cloud data with XYZ coordinates. From the created 3D digital texture model, selected texture parameters were calculated and compared to the frictional performance of the pavements determined for inspected surfaces by using standard pendulum device.

No abstract

Ocjena strukturalnog stanja kolnika definira ukupnu nosivost kolnika, a određuje se kroz ocjenu mehaničkih svojstava slojeva kolničke konstrukcije. Defleksija predstavlja elastičnu deformaciju kolničke konstrukcije i jedan je od važnih pokazatelja strukturalne nosivosti kolnika. Iznos defleksije moguće je utvrditi teorijski, korištenjem zakonitosti teorije elastičnosti i poznavanjem materijalnih svojstava kolničke konstrukcije, ili empirijski, mjerenjem elastične deformacije generirane poznatim statičkim ili dinamičkim opterećenjem na površini kolnika, najčešće korištenjem uređaja s padajućim teretom (FWD uređaj). U ovom radu opisane su teorijske metode za određivanje strukturalne nosivosti kolničke konstrukcije, s naglaskom na defleksiju kao prevladavajući tehnički parametar za utvrđivanje ocjene strukturalnog stanja kolnika. Opisan je empirijski postupak utvrđivanja defleksije FWD uređajem te je dan pregled utjecajnih činitelja na izmjerene iznose defleksije. Prikazani su indeksi proizašli iz mjerenja defleksije, koji se koriste za utvrđivanje strukturalne ocjene kolnika. Na primjeru analize stanja kolničke konstrukcije provedene u sklopu diplomskog rada prikazana je važnost provedbe kontinuiranog mjerenja u svrhu utvrđivanja strukturalnog stanja i ocjene kolničke konstrukcije.