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The most important factor that affects concrete deterioration is the appearance of cracks on reinforced concrete (RC) structures, so the influence of loading cracks should not be neglected when the service life is analyzed. For the purposes of this research, reference concrete and concretes with 50% fly ash (FA) and with 100% recycled aggregate (RCA) were prepared. The existing carbonation prediction models were analyzed and modification was proposed in the case of FA and RCA concretes. After establishing the relationship between carbonation resistance and compressive strength, the service life analysis was performed by defining the required concrete cover depth for different concrete types. Samples with 5 different crack widths (0.05, 0.10, 0.15, 0.20 and 0.30mm) and samples without cracks were prepared and subjected to accelerated carbonation. For all concrete types steel stress limitation was pro-posed, which allows the entire service life of RC elements to meet the prescribed requirements.

Trajnost betona definisana je njegovom otpornošću na dejstvo štetnih agenasa iz okolne sredine koji dovode do različitih vrsta oštećenja (mehanizmi deterioracije). U ovoj tezi, kroz pregled literature, izvršena je analiza postojećih rezultata istraživanja i znanja o glavnim mehanizmima deterioracije koji predstavljaju najveću opasnost za objekte u različitim klimatskim sredinama. Mehanizmi deterioracije mogu uticati na strukturu betona (mraz i soli za odmrzavanje) ili na pojavu korozije armature unutar betona (karbonatizacija i penetracija hlorida). Na deterioracione mehanizme i koroziju koja nastaje njihovim dejstvom u velikoj meri utiče prisustvo prslina. Prsline koje nastaju kao posledica savijanja presecaju armaturu i znatno olakšavaju prodor kiseonika i vode. Shodno tome, uloga prslina prouzrokovanih opterećenjem ne sme se zanemariti u sagledavanju upotrebnog veka armiranobetonskih (AB) konstrukcija. Korozija izazvana hloridima bila je predmet mnogih istraživanja proteklih godina. Za razliku od nje, u literaturi postoji vrlo malo podataka o uticaju prslina na koroziju armature izazvanu karbonatizacijom, pogotovo na razvoj korozije tokom vremena. Došlo se do zaključka da deterioracija AB konstrukcija usled korozije armature izazvane karbonatizacijom predstavlja jedan od glavnih problema trajnosti širom sveta, imajući u vidu da je veliki broj infrastrukturnih objekata izložen okruženju bogatom ugljen–dioksidom (CO2). Zbog toga je karbonatizacija postala važno pitanje u analizi trajnosti AB konstrukcija. Da bi se generisalo novo znanje i doprinelo poboljs anju postojećih standarda i inz enjerske prakse, razvijena je odgovarajuća eksperimentalna postavka kako bi se ispitao uticaj prslina na dubinu karbonatizacije i trajnost AB elemenata napravljenih od različitih vrsta betona... Durability of concrete is defined by its ability to resist harmful environmental agents that damage concrete (deterioration mechanisms). In this thesis an analysis of existing knowledge about most harmful deterioration mechanisms in different climates was made. These mechanisms affect inner concrete structure (freeze/thaw with de-icing salt) or induced reinforcement corrosion (carbonation and chloride penetration). The most important factor that affects concrete deterioration is the appearance of cracks on reinforced concrete (RC) structures. The presence of cracks that cross the reinforcement physically interrupts the passivation layer and induces the beginning of corrosion. Accordingly, the influence of cracks should not be neglected when the service life of RC structures is analysed. Chloride induced corrosion has been the subject of many studies in recent years, but there is a very little information about the influence of cracks on carbonation induced corrosion. Furthermore, deterioration of RC structures due to carbonation induced corrosion is one of the major durability issues worldwide, given that a large number of structures are exposed to a carbon dioxide (CO2) rich environment. Therefore, carbonation has become an important issue in RC structures durability analysis. In order to generate new knowledge and contribute to the improvement of existing standards and engineering practice, an appropriate experimental setup was developed to evaluate the influence of crack widths on the carbonation depth and durability of RC elements made from different concrete types...

U disertaciji su prikazani rezultati sopstvenog eksperimentalnog istraživanja mogućnosti primjene biopepela, nastalog sagorjevanjem žetvenih ostataka, kao mineralnog dodatka u cementnim kompozitima: malterima i betonima. Istraživanje je zasnovano na komparativnoj analizi 27 vrsta maltera u kojima je varirana vrsta biopepela i vrsta sitnozrnog agregata i 12 vrsta betona koje se razlikuju u vrsti veziva i u krupnom agregatu. Na očvrslom malteru su ispitani: konzistencija, čvrstoća pri pritisku i kapilarno upijanje vode, a na očvrslom betonu ispitivani su kapilarno upijanje vode, skupljanje pri sušenju, čvrstoća pri pritisku, dinamički modul elastičnosti, otpornost na habanje, vodonepropustljivost i čvrstoća na savijanje. Istaknuto je da se primjenom biopepela kao zamjene dijela cementa mogu dobiti konstrukcijski malteri i betoni, odnosno betoni sa zadovoljavajućim fizičkim i mehaničkim karakteristikama., The dissertation presents the results of an own experimental research on the possibility of using biomass ash as a mineral additive in cement composites: mortar and concrete. The research is based on a comparative analysis of 27 types of mortars in which the type of biomass ash and the type of fine-grained aggregate were varied, as well as 12 types of concrete that differ in the type of binder and coarse aggregate. Following properties were tested on hardened mortars: consistency, compressive strength and capillary water absorption, and on hardened concrete: capillary water absorption, drying shrinkage, compressive strength, dinamic modulus of elasticity, wear resistance, waterpermeability and flexural strength. It was pointed out that biomass ash can be used as a replacement of a part of cement, thereby obtaining satisfactory physical and mechanical characteristics.

U cilju implementacije i promocije održivog razvoja u oblasti graditeljstva, sprovedena su obimna eksperimentalna ispitivanja kako karakteristika recikliranog agregata (RCA), tako i karakteristika asfaltnih mešavina sa delimičnom zamenom prirodnog agregata recikliranim. Reciklirani agregat koji je korišćen u istraživanju dobijen je drobljenjem originalnog cementnog betona klase čvrstoće C35/45. U cilju poboljšanja kvaliteta recikliranog agregata, krupan RCA (d>4 mm) je izložen tretmanima hlorovodoničnom kiselinom (potapanjem u 0.1 mol/dm3 HCl) i ubrzanoj karbonatizaciji (koncentraciji CO2 od 4%). Pomenutim tretmanima su u manjoj meri poboljšane karakteristike RCA, pa su dalja ispitivanja uticaja RCA na karakteristike asfalt betona sprovedena samo za netretirani RCA. Eksperimentalnim ispitivanjima je obuhvaćeno 10 asfaltnih mešavina. Osim kontrolne mešavine, formirane su tri grupe mešavina sa delimičnom zamenom sitnog (0/4 mm), krupnog (4/22.5 mm) i sitnog i krupnog (0/22.5 mm) prirodnog agregata recikliranim. Svaku grupu su činile mešavine sa tri različita sadržaja RCA: 15%, 30% i 45%. Projektovane su asfaltne mešavine za noseći sloj kolovozne konstrukcije AC 22 BASE sa ciljanim sadržajem šupljina ispunjenih vazduhom od 5.2%. Glavni deo eksperimentalnog rada je obuhvatio ispitivanje modula krutosti i otpornosti asfalntih mešavina na dejstvo vode, trajnu deformaciju, zamor i niske temperature. Dobijeni rezultati su pokazali da je moguća primena kompletnog RCA (i sitan i krupan agregat); da mešavine sa RCA imaju istu ili bolju otpornost na zamor u odnosu na kontrolnu mešavinu; i da je maksimalna količina RCA u manjoj meri ograničena otpornošću na niske temperature. Na osnovu analize dobijenih rezultata razvijena je metodologija za upotrebu RCA kao delimične zamene prirodnog agregata i date su preporuke za dalja istraživanja. As a part of the implementation and promotion of sustainable construction development, large experimental research was conducted. This research included testing of the recycled concrete aggregate (RCA) and properties of asphalt mixtures in which this aggregate was applied as a partial replacement of the natural aggregate. Recycled concrete aggregate used in the conducted experiments was obtained by crushing of the original cement concrete (strength class C35/45). In order to improve it's quality, coarse RCA was exposed to the treatments with hydrochloric acid (by pre-soaking into 0.1 mol/dm3 HCl) and carbon dioxide (accelerated carbonation with 4% concentration of CO2). Mentioned treatments induced improvements in the properties of RCA, to a lesser extent. Therefore, only untreated RCA was used as a partial replacement of the natural aggregate in production of asphalt mixtures. Experimental research was conducted on the 10 different asphalt mixtures. Three groups of mixtures with RCA were tested in addition to the control mixture. In the first group, only fine aggregate (0/4 mm) was replaced by RCA; in the second group, the replacement was applied only to coarse aggregate (4/22.4 mm), while the third group included mixtures in which both fine and coarse aggregate were replaced by RCA. Each group included three different contents of RCA: 15%, 30%, and 45%. All asphalt mixtures were designed for the base course AC 22 BASE, targeting 5.2% of air entrained voids. Main part of the experiment consisted of different asphalt mixture’s testing, such as measurements of: the stiffness modulus, resistance to water, permanent deformation, fatigue and low temperatures. Obtained results show that application of the total (both fine and coarse) RCA is possible as mixtures with RCA expressed equal or improved fatigue resistance when compared to the referent mixture. Still, the amount of the RCA used should be limited according to its low temperatures resistance. Methodology for the RCA application, when it is used as a partial replacement of the natural aggregate in asphalt mixtures, was developed based on the presented results, together with guidelines for the future research.

The application of recycled concrete aggregate in concrete structures is necessary for the achievement of sustainable construction and a reduction in the negative environmental impacts. This paper presents the most significant research into the phenomenon of shrinkage of recycled aggregate concretes. Since the amount of research is still relatively small, this paper presents an attempt to systematize them, present their results and analyze them. It is shown that the shrinkage of recycled aggregate concrete is mostly larger than the shrinkage of the reference natural aggregate concrete and that this difference increases as the percentage of recycled concrete aggregate increases. The effect of the water-to- cement ratio has also been analysed.