Organising aspects of the Levels Added Organisation (LAO)

How to achieve a more efficient, more successful, and above all more competitive organisation in the given environment and equal spare time in everything? One of responses is evidently hidden in the levels added organisation concept, which has already proved its advantages in some domains practice, and now we also try to define and explain them from the organisational and scientific aspect. As briefly presented in this paper, the nucleus is hidden in the evolutionary development of the organisation that adopts innovations, then tests and evaluates them, combines and upgrades them, and consequently it efficiently resolves difficulties of existent organisational concepts

Energy harvesting potential from vehicular traffic crossing road humps in the case of Slovenia

Based on the fact that in Slovenia the main roads are planned in accordance with the valid regulations, which do not specifically separate the roads according they are inside or outside urban areas, such infrastructures were built on the criteria of relevant capacity (normally wide and narrow multi or single lane roads). With the goal to guarantee the quality of life and especially traffic safety (decrease of average speed in urban areas) traffic calming measures were needed. In most cases in urban areas speed humps and platforms were installed, which effectively slow down the speed, but on the other hand massive increase ground-borne vibrations, produced by vehicles passing over these “road irregularities”. Please click Additional Files below to see the full abstract

Potential reduction of concrete deterioration through controlled DEF in hydrated concrete

Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on hydrated concrete. Ettringite crystals can cause cracks and their widening due to pressure on cracked walls caused by the positive volume difference in the reaction. Concrete may show improvements in strength at early ages but further growth of cracks causes widening and spreading through the concrete structure. In this study, finely dispersed crystallization nuclei achieved by adding air-entraining agent (AEA) and short vibration of specimens is presented as the main prerequisite for reducing DEF-induced deterioration of hydrated concrete. The study presents the method and mechanism for obtaining the required nucleation. Controlling long-term DEF by providing AEA-induced crystallisation nuclei, prevented excessive and rapid initial strength improvements, and resulted in a slight increase of compressive strength of fine grained concrete with only marginally lower density

Experimental Investigation of the Effect of Temperature on the Structures in the Measurement of Displacements

Measurement of displacement and deformation of structures is a very demanding engineering task and is carried out on all existing and newly built bridges and other demanding structures. The results of the measured displacements are thus influenced by several atmospheric parameters, among which the temperature is exposed, since the measurements are usually carried out over the whole day at different seasons and conditions, where the temperature differences are significant. In this paper the influence of temperature on the geodetic measurements of the displacements of the steel structure in the unburdened state is presented. To this end, measurements of the steel bridge during the summer time were performed. The temperature and thermal imaging at various locations every half hour were investigated. To calculate the influence of the temperature on the position of the observed point some statistical methods were used. It is evident from the results that in this kind of geodetic measurements, temperature measurements are indispensable. By taking into account the temperature correction results that are very comparable with the predicted values of displacements which can be obtained. Not observing the temperature can result in misleading values of displacement which can lead to misinterpretation and consideration of the obtained value

DIJAGNOSTICIRANJE UZROKA DEGRADACIJE ŠUPLJIH OPEČNIH BLOKOVA UGRAĐENIH U STROPNU ARMIRANOBETONSKU KONSTRUKCIJU

U konstrukciji montažnih stropova od šupljih opečnih blokova, koji su element ispune između nosivih armiranobetonskih greda, u razdoblju od četiri godine poslije njihove izgradnje došlo je do znatnih oštećenja. Oštećenja stropova manifestirala su se odlamanjem dijelova šupljih opečnih blokova, što je ugrožavalo sigurnost ljudi. Uporabom optičkog mikroskopa i elektronskog mikroskopa, kao i kemijske mikroanalize EDS (Energy Dispersive System), analizirana je oštećena keramika te je utvrđena prisutnost iskristalizirane soli. EDS analizom utvrđena je prisutnost kemijskih elemenata (Al i S), koji uz utvrđenu morfologiju kristala ukazuju na mogućnost prisutnosti minerala etringita (Al2O33CaSO4 x 32H2O). Numeričkom analizom uz primjenu metode konačnih elemenata, uporabom računalnog programa COSMOS Design STAR 3.0 od SRAC (Structural Research and analisis Corporation USA), procijenjen je utjecaj temperaturnih opterećenja na koncetraciju naprezanja na vrhu mikropukotina i na njihovo širenje. U numeričkoj analizi eksperimentalno su uzeta u obzir određena fizikalno-mehanička svojstva materijala. Analizirani su primjeri šupljih opečnih blokova s prisutnošću bijelih kristala i bez njih. Prikazan je raspored faktora sigurnosti po modelu u odnosu na Mises-ovu hipotezu razaranja. Rezultati eksperimentalnih i numeričkih istraživanja pokazali su da kemijska degradacija šupljih opečnih blokova, u kombinaciji s temperaturnim opterećenjem koje nastaje zbog promjena klimatskog režima, može uzrokovati takva oštećenja te da je time ugrožena i sigurnost konstrukcije

Influence of cure on the properties of polymer-modified mortars

U radu se opisuje upotreba mikroarmiranog morta s vlaknima od propilena pri sanaciji plašta dimnjaka termoelektrane Šoštanj u Sloveniji. Prikazana je analiza kvalitete ugrađenog mikroarmiranog morta uzimajući u obzir različite uvjete pripreme, ugradnje i njege. Uspoređeni su rezultati ispitivanja fizikalno-mehaničkih svojstava uzoraka uzetih s građevine s uzorcima izrađenim u laboratoriju. Autori zaključuju da je za mortove s dodatkom polimera nužna kratkotrajna mokra njega.The use of propylene-fibre reinforced mortar in the remedy of the chimney stack sheathing at the Šoštanj thermal power plant in Slovenia is presented. The fibre reinforced mortar quality analysis is presented for various preparation, placing and cure conditions. Physicomechanical properties of samples taken from the structure are compared with properties of samples prepared in laboratory. The authors conclude that the short-term wet curing is required for polymer-modified mortars

STRENGTH IMPROVEMENT WITH DELAYED ETTRINGITE FORMATION

Zakasnela tvorba etringita (Delayed Ettringite Formation - DEF) je kemična reakcija z dokazano škodljivim vplivom na hidratizirani beton. Kristali ki pri tej kemični reakciji nastanejo lahko povzročijo nastanek razpok. Pozitivne spremembe prostornine, ki je posledica nastalih produktov prav tako poveča pritiske na stene razpok in poroznih mestih. Zaradi rasti kristalov etringita ima lahko mlad hidratizirani beton višje trdnosti, kar pa navadno pomeni spremljajoč pojav nastanek razpok in razpad betona. V disertaciji smo raziskali možnosti kako izkoristiti pozitivne volumensko spremembo, ki je posledica DEF za izboljšanje trdnostnih lastnosti drobno zrnatega betona.. Ugotovili smo, da z dodajanjem aeranta in zelo kratkim časom vibriranja betona dosežemo takšno strukturo betona, kjer zračni mehurčki v hidratiziranem betonu predstavljajo nukleacijska mesta. Zakasnela tvorba etringita je z razpršenimi zračnimi mehurčki, ki so nastali od aeranta kontrolirana. Rast kristalov etringita ne povzroči hitrega povečanja trdnosti in razapada betona temveč v fazi stabilizacije strukture doprinese 6% povečanje tlačne trdnosti ob minimalnem znižanju gostote hidratiziranega drobno zrnatega betona.Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on hydrated concrete. Ettringite crystals can cause cracks and their widening due to pressure on crack walls caused by the positive volume difference in the reaction. Concrete may show improvements in strength at early ages but further growth of cracks causes widening and spreading of these cracks through the concrete structure. In this study, a potential to utilise the positive volume difference in DEF in order to improve mechanical properties of hydrated fine grained concrete is investigated. Finely dispersed crystallization nuclei achieved by adding air-entraining agent (AEA) and short vibration of specimens is presented as the main prerequisite for such improvements. The study presents the method and mechanism for obtaining the required crystallisation nuclei. Controlling long-term DEF by providing AEA-induced crystallisation nuclei prevented excessive and rapid initial strength improvements, and resulted in a 6% increase of compressive strength of fine grained concrete with only marginally lower density

Organising aspects of the Levels Added Organisation (LAO)

How to achieve a more efficient, more successful, and above all more competitive organisation in the given environment and equal spare time in everything? One of responses is evidently hidden in the levels added organisation concept, which has already proved its advantages in some domains practice, and now we also try to define and explain them from the organisational and scientific aspect. As briefly presented in this paper, the nucleus is hidden in the evolutionary development of the organisation that adopts innovations, then tests and evaluates them, combines and upgrades them, and consequently it efficiently resolves difficulties of existent organisational concepts

Durability and Degradation of PVC-P Roofing Membrane—Example of Dynamic Fatigue Testing

This paper presents a study of PVC-P waterproofing membrane Specimens. The Specimens were taken from different segments of a flat roof after a service life of 11 years. The reason for analysing the condition of the Specimens was the apparent degradation of the waterproofing, which no longer guaranteed the watertightness of the roof. The analysis of the performance of the Specimens was based on the control of the mechanical properties, which were compared with the declared values. The mechanical properties of the degraded PVC-P waterproofing membranes with a polyester mesh backing, which are prescribed by the standards, do not usually deviate from the declared properties. This often poses a problem for liability and warranty claims due to the poor quality of the waterproofing membrane. There may be several causes of degradation of PVC-P. For this reason, in this paper, we present the possibility of controlling the properties of PVC-P waterproofing membranes using cyclic dynamic fatigue, microstructure analysis using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the cause of the deterioration of the PVC-P waterproofing membranes is often related to dehydrochlorination of the polymer. However, the deterioration of the mechanical properties of the PVC-P waterproofing membranes can be successfully demonstrated by cyclic dynamic fatigue