EFFECT OF BITUMEN EMULSION ON MECHANICAL PERFORMANCE OF COLD ASPHALT MIXTURES

Abstract. Implementation of innovative material and evaluation concepts in pavement construction industry is important to reduce the negative environmental impacts. The objective of this paper is to review the recent scientific developments in characterising the effect of bitumen emulsion properties on the performance of cold asphalt mixtures. The experimental approach was based on the indirect tensile testing of the standardised bitumen emulsion mortar specimens. The major finding is that there is a continuous change in mechanical properties and the mode of fracture on the long-term basis. However, the ratios of the considered fracture performance-related parameters indicated that the change in the mode of fracture from ductile to brittle is not that direct, and the reason for this could be in the relation between the development of the adhesion and the residual binder viscosity. As a step towards fundamental understanding of the contribution of adhesion, further research should be focused on the interaction between cement hydration, binder droplets, and emulsifier. Keywords: bitumen emulsion, asphalt mixtures, indirect tensile testing, mechanical performance, fracture

Tehnologije asfaltnih mešavina po toplom postupku u Evropi i SAD

Warm-mix asphalt (WMA) represents the group of technologies that enables reduction of temperatures at which the asphalt mixture is produced and placed. WMA is produced at 20 to 55°C lower temperatures than those typical for hot-mix asphalt (HMA). Consequently to lower temperatures, WMA has a set of benefits comparing to HMA. Primary benefits of WMA include reduced fuel and energy consumption, reduced green house gasses (GHG) and other harmful substances emissions, reduced workers exposure to harmful impacts, particularly with mastic asphalt, and range of other paving benefits. Hence, the development of WMA technologies application could be significant contribution towards sustainable development concept realization. General expectation of WMA is that their overall performance is equal of better then HMA, which is proven by some laboratory investigations and short-term field performance in Europe (3 years of less). Further application of WMA also requires adjusting of pavement performance related specifications. .Asfaltne mešavine po toplom postupku (warm-mix asphalt, WMA), predstavljaju grupu tehnologija koje omogućavaju snižavanje temperatura na kojima se asfaltna mešavina proizvodi i ugrađuje. WMA se proizvodi na oko 20 do 55°C nižim temperaturama nego što je to uobičajeno za asfaltne mešavine po vrućem postupku (HMA). Kao posledica niže temperature, WMA ima niz prednosti u poređenju sa HMA mešavinama. Osnovne prednosti WMA uključuju smanjenu potrošnju goriva i energije, smanjenu emisiju gasova staklene bašte (GHG) i drugih štetnih materija, smanjenu izloženost radnika štetnim uticajima, posebno kada je u reč o livenom asfaltu, i niz prednosti u pogledu ugrađivanja. Stoga, razvoj primene WMA tehnologija bi mogao predstavljati značajan doprinos realizaciji koncepta održivog razvoja. Opšte očekivanje u pogledu WMA je da njihovo sveukupno ponašanje bude podjednako dobro ili bolje od HMA, što je potvrđeno nekim laboratorijskim ispitivanjima i kratkoročnim ponašanjem na terenu u Evropi (3 godine ili manje). Dalja primena WMA zahteva i prilagođavanje specifikacija u pogledu ponašanja kolovoznih konstrukcija u eksploataciji

Software for Measuring Acoustic Parameters in Open-plan Offices

This paper presents a development of software for the measurement and estimation of the quality of acoustic design in open-plan offices. The measurement method is defined by a standard and measurements should be performed in a large number of different spatial positions in order to measure and determine the acoustic quality of the surroundings of as many workstations as possible. The presented software significantly simplifies the process of analyzing open-plan offices by processing the signal at the time of measurement. Furthermore, it allows for the storing of measured signals and parameter values, which can be of importance for further analysis or repeated calculations. The presented procedure leads to the reduction of the necessary hardware elements for completing the analysis. All that is needed for measurement are a sound source, a microphone, a sound card and a computer. As a result, the user obtains a detailed report of the characteristics of the analyzed office space and a descriptive mark which depends on the values of the calculated parameters

MULTI-CRITERIA SELECTION OF STANDARDS FOR SYSTEM ANALYST ACTIVITIES IN ORGANIZATIONS

The paper defines the methodology for the selection of standards and tools that system analysts use for the purposes of analyzing the computer infrastructure of organizations. The goal of system analyst analysis is primarily to increase: the speed of processing information, the efficiency of data processing and data exchange. A large number of standards and tools complicates an adequate choice, and on the other hand system analysts are not the only ones who influence the choice. In the analysis of the choice of standards and tools, in the second chapter an algorithm for determining the weight coefficients for the criteria selected by the company and the ranking of the standards for selection is presented through an example. In order to choose the best standard, the choice was made between four standards described in the third chapter. The chapter defines the criteria that cover IT activities for the selection of standards according to selected criteria and defined weight coefficients in the observed company. Finally, on the assumption that the company together with the analyst chose “k” criteria, where the methodology (LBWA) for the selection of weight coefficients for the criteria was proposed, a new model for calculating the ranking of standards was presented, i.e. the choice of the best. The conclusion of the paper is that the presented procedure for choosing standards is not complicated, that it is very successful, and that in this way the proposals were more easily accepted and implemented in the fastest way

Influence of bitumen emulsion and reclaimed asphalt on mechanical and pavement design-related performance of asphalt mixtures

Das Ziel dieser Forschung war ein Verfahren für die Charakterisierung der Bitumenemulsionen entwickeln. Deswegen wurden die Konzepte des Bitumenemulsions-Mörtels und der Asphalttragschicht berücksichtigt. Die Gemische für die Asphalttragschicht wurden mit unterschiedlichen Mengen und Arten des Asphaltgranulates zusammengesetzt. Die mechanische Eigenschaften der Probekörper wurden ausgewertet aufgrund es Spaltzug- und Spaltzugschwellversuchs. Standard-Bauweisen wurden die rechnerische Dimensionierung vorgeschlagen. Die bedeutendste Änderung der physikalischen Eigenschaften fand innerhalb der erste 28 Tage statt, und die Entwicklung der mechanischen Eigenschaften noch wenige Monate danach sich fortsetzt. Der Emulgator war sehr einflussreiches Mittel um das Mischgutverhalten zu beeinflussen. Höhere Mengen des Asphaltgranulats resultiert in meistens besseres mechanisches Verhalten und die Anwendung ist möglich für verschiedene Verkehrsbelastungen

Tehnologije asfaltnih mešavina po toplom postupku u Evropi i SAD

Warm-mix asphalt (WMA) represents the group of technologies that enables reduction of temperatures at which the asphalt mixture is produced and placed. WMA is produced at 20 to 55°C lower temperatures than those typical for hot-mix asphalt (HMA). Consequently to lower temperatures, WMA has a set of benefits comparing to HMA. Primary benefits of WMA include reduced fuel and energy consumption, reduced green house gasses (GHG) and other harmful substances emissions, reduced workers exposure to harmful impacts, particularly with mastic asphalt, and range of other paving benefits. Hence, the development of WMA technologies application could be significant contribution towards sustainable development concept realization. General expectation of WMA is that their overall performance is equal of better then HMA, which is proven by some laboratory investigations and short-term field performance in Europe (3 years of less). Further application of WMA also requires adjusting of pavement performance related specifications. .Asfaltne mešavine po toplom postupku (warm-mix asphalt, WMA), predstavljaju grupu tehnologija koje omogućavaju snižavanje temperatura na kojima se asfaltna mešavina proizvodi i ugrađuje. WMA se proizvodi na oko 20 do 55°C nižim temperaturama nego što je to uobičajeno za asfaltne mešavine po vrućem postupku (HMA). Kao posledica niže temperature, WMA ima niz prednosti u poređenju sa HMA mešavinama. Osnovne prednosti WMA uključuju smanjenu potrošnju goriva i energije, smanjenu emisiju gasova staklene bašte (GHG) i drugih štetnih materija, smanjenu izloženost radnika štetnim uticajima, posebno kada je u reč o livenom asfaltu, i niz prednosti u pogledu ugrađivanja. Stoga, razvoj primene WMA tehnologija bi mogao predstavljati značajan doprinos realizaciji koncepta održivog razvoja. Opšte očekivanje u pogledu WMA je da njihovo sveukupno ponašanje bude podjednako dobro ili bolje od HMA, što je potvrđeno nekim laboratorijskim ispitivanjima i kratkoročnim ponašanjem na terenu u Evropi (3 godine ili manje). Dalja primena WMA zahteva i prilagođavanje specifikacija u pogledu ponašanja kolovoznih konstrukcija u eksploataciji

Influence of ethylene-vinyl acetate on the performance improvements of low-density polyethylene-modified bitumen

Due to the low recyclability and slow degradation in nature, waste polyethylene (PE) represents a negative effect on the environment and its disposal is discordant with the idea of sustainable development in general. On the other hand, the application of the polymer-modified bitumen is an economical and efficient alternative for improving the performance of asphalt pavements. However, the thermal storage stability of PE-modified bitumen is the main factor that prevents its wider application. The main objective of this research was to investigate the feasibility and to quantify the effect of the addition of ethylene-vinyl acetate (EVA) on PE-modified bitumen. This was achieved by testing the modified bitumen produced with the single mass fraction of PE of 4% and different mass fractions of EVA in the range from 2 to 8%. The experimental program included penetration, softening, ductility, rheological properties in high-and low-temperature range, thermal storage stability and compatibility of phases, environmental scanning electron microscopy, and Fourier transform infrared spectroscopy. The results indicated that the addition of EVA increased the viscosity, complex shear modulus, as well as the elasticity of bitumen. Although the high-temperature behaviour was improved, the behaviour in the low temperature range was practically unaffected. The storage stability and segregation of phases were positively affected to a remarkable extent. The base bitumen and PE interacted only physically, but some particular chemical interaction took place with the addition of EVA

Copeptin Levels Do Not Correlate With Cross-Clamping Time in Patients Undergoing Carotid Endarterectomy Under General Anesthesia

Copeptin is a sensitive and more stable surrogate marker for arginine vasopressin. In this study, we evaluated copeptin levels in carotid endarterectomy (CEA) patients, perioperatively, to determine whether copeptin levels can be related to carotid artery cross clamping (CC) time and to postoperative neurological outcomes. Copeptin, interleukin 6, C-reactive protein, cortisol, and brain natriuretic peptide were measured preoperatively (T1) and 3 hours postoperatively (T3) as well as intraoperatively (T2). We recruited 77 patients. Values of copeptin rose gradually over the observed times: T1 = 7.9 (6.4-9.6), T2 = 12.6 (9.3-16.8), and T3 = 72.3 (49.1-111.2) pmol/L. There was a significant difference for repeated measurement (P = .000, P = .000, and P = .000). Duration of carotid artery CC during CEA does not affect postoperative copeptin level (CC 13 minutes: 106.8 +/- 93.6 pmol/L, CC > 13 minutes: 96.7 +/- 89.1 pmol/L; P = .634). Preoperative copeptin level was significantly higher in patients with ulcerated plaque morphology. Activation of the stress axis in patients undergoing CEA results in copeptin elevation. Duration of CC during CEA does not affect postoperative copeptin levels

PROTECTIVE POSSIBILITIES OF THE AUTOTRANSPLANTATION OF THE INJURED SPLEEN

The spleen autotransplantation is a conserving method that is indicated in the most serious injuries of the spleen followed by the jarring of the parenchyma or total devascularization of the organ when it is impossible to apply any other conserving procedure.After multiple devascularizing injuries of the spleen of the fifth degree were induced, 20 dogs were subjected to autotransplantation of the organ while the same number of the animals was primary splenectomized. Two months and a half after the conserving operation, that is, splenectomy, all the animals (from both the groups) were exposed to an intravenous inoculation of the sublethal doses of pneumococci for the sake of perceiving immunological efficiency of the conserved tissue and compa-ring the mortality rate from the pneumococci sepsis between the two examined groups.The positive hemoculture and the logarithmic increase of the number of diplococcus in the blood samples are registered in all 40 animals. A higher mortality rate and a highly significant increase of the bacteria in blood are registered in the group of splenectomized animals with respect to the auto transplanted group.The obtained results point to the immunoprotective advantage of the conserving actions with respect to the classical splenectomic procedure