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The behaviour of novel cementitious materials (low clinker cement CEM II/C and CEM VI) exposed to CO2 is simulated and investigated with a simplified model in this paper. Based on studies of the evolution of the phase assemblage obtained from GEMS, the carbonation process is simplified into the dissolution of one combined Cacontaining phase and the precipitation of calcite phase. The purpose is to quantify some physical variables representative of the reactive transport properties: saturation degree for drying, porosity, calcite and Ca-containing phase content for carbonation. The dissolution rate of the Ca-containing phase and corresponding precipitation of calcite are assumed to be determined by the saturation degree, the partial pressure of CO2, and the concentration of calcium in solid phases. The carbonation process is assumed to be ruled by two phenomena: the water migration through the connected porosity and the diffusion of carbon dioxide in the gaseous phase, which are governed by two mass conservation equations. This model is solved by the finite element code Cast3M, and is verified using experimental data from carbonation depth measurements using a pH indicator, portlandite and carbonate profiles from thermogravimetric analysis and drying experiments on mortar and concrete.

Este documento presenta la estructura y los resultados del proyecto InnoWEE (Programa de I+D+i Horizonte 2020, Convocatoria EeB-04-2016, Acuerdo de Subvención No 723916), y ofrece una visión general de sus principales fases y logros.

Ta dokument predstavlja strukturo in rezultate projekta InnoWEE (Program R&I Obzorje 2020, razpis EeB-04-2016, pogodba o donaciji št. 723916) in podaja pregled njegovih glavnih faz in dosežkov.

Αυτό το έγγραφο παρουσιάζει τη δομή και τα αποτελέσματα του έργου InnoWEE (Horizon 2020 R&I Πρόγραμμα, CallEeB-04-2016, Συμφωνία επιχορήγησης αρ.723916) και παρέχει μια επισκόπηση των κύριων φάσεων και επιτευγμάτων του.

During carbonation of concrete, CO2 from the atmosphere is dissolving in water and forming carbonic acid that reacts with different calcium bearing phases inside cementitious matrix, mainly CH and C-S-H. This reaction leads to the changes in mineralogical composition of the matrix, causing changes in durability properties of concrete. In this study, carbonation induced changes in durability properties were evaluated for mortars with three different binder compositions: i) ordinary Portland cement, ii) blended cement with slag, iii) blended cement with high volume of fly ash and silica fume. Compressive strength, chloride migration and capillary absorption of different concrete types were tested after exposure to 4% CO2 lasting for 2, 4 and 8 weeks. Changes in mechanical and durability properties were compared to samples that were not exposed to CO2 and were connected to changes in porosity and mineralogical composition of mortars. Results indicate that the changes in durability properties differ depending on the composition of the binder, which could have an important effect on the service life modelling of structures with blended cements.

The Extended Round Robin Testing program (RRT+) is used in the Working Group 1 (WG1) of COST Action: i) to validate advanced and non-standardised experimental techniques for testing cement-based materials, ii) to benchmark different sustainable variations of concrete mixes prepared with mineral admixtures, recycled materials and/or byproducts, and iii) to gather the range of input properties for the mixes studied at different scales (paste, mortar and concrete) which could serve designers and engineers to better predict lifespan, durability, and serviceability of concrete structures. The RRT+ is divided into two phases: the Initial Phase, which was completed in March 2016, and the Main Phase, which started in November 2016. This paper describes the organization and the current progress of the Main experimental phase. Besides, it gives an outlook on the continuation of the work and future actions., Authors also acknowledge financial support of EDF, France, CEVA Logistics, Austria and Germany, OeBB Infra, Austria, Staten Vegvesen, Norway and Schleibinger Gerate, Germany. The support of the research network COST TU1404 (COST Association) is also gratefully acknowledged. Portuguese FCT and FEDER (COMPETE2020) are also acknowledged for the funding of the research project IntegraCrete PTDC/ECM-EST/1056/2014 (POCI-01-0145-FEDER016841)., info:eu-repo/semantics/publishedVersion

The railway infrastructure is a very important component of the world%s total transportation network. Investment in its construction and maintenance is significant on a global scale. Previously published life cycle assessment (LCA) studies performed on road and rail systems very seldom included infrastructures in detail, mainly choosing to focus on vehicle manufacturing and fuel consumption. This article presents results from an environmental study for railway steel bridge materials for the demonstration case of the Buna Bridge in Croatia. The goal of these analyses was to compare two different types of remediation works for railway bridges with different materials and construction types. In the first part, the environmental impact of the classical concrete bridge construction was calculated, whereas in the second one, an alternative new solution, namely, the strengthening of the old steel bridge with ultra-high-performance fibre-reinforced concrete (UHPFRC) deck, was studied. The results of the LCA show that the new solution with UHPFRC deck gives much better environmental performance. Up to now, results of LCA of railway open lines, railway bridges and tunnels have been published, but detailed analyses of the new solution with UHPFRC deck above the old bridge have not previously been performed. Železniška infrastruktura je zelo pomemben del celo - tnega transportnega omrežja. Gradnja in vzdrževanje prog tudi v svetovnem merilu predstavlja velik strošek. Dosedanje LCA študije (analiza življenjskega cikla), iz - vedene na cestnih in železniških omrežjih zelo redko vključujejo podrobno analizo infrastrukture, večino - ma se osredotočijo na porabo goriva za proizvodnjo in pogon vozil. V prispevku so predstavljeni rezultati iz okoljske študije za uporabljene materiale železniškega mostu %Buna most% na Hrvaškem. Cilj te analize je bil primerjati dve različni metodi sanacije starega mostu s poudarkom na uporabi različnega materiala in za različne tipe konstrukcij. V prvem delu je bil izračunan vpliv na okolje za klasično betonsko konstrukcijo mo - stu, medtem ko je v drugem prikazan izračun za novo alternativno rešitve sanacije mostu; ojačanje starega jeklenega mostu s UHPFRC (mikroarmiran beton zelo visokih zmogljivosti) ploščo. Rezultati LCA kažejo, da ima nova rešitev z UHPFRC ploščo veliko manjši vpliv na okolje kot klasična betonska konstrukcija. Do sedaj objavljene LCA študije so se večinoma osredotočale na analize gradnje in sanacije odprtih železniških prog, železniških mostov in predorov. Za novo alternativno metoda, sanacije železniškega mostu z UHPFRC ploščo, okoljska LCA analiza do sedaj še ni bila objavljena.

Nowadays on the existing railway infrastructures many bridges can be found that have been built more than 50 years ago, and which were not designed for current loads and high speed trains. These are mainly bridges from hot rolled steel or cast iron and connected with rivets. The main idea of strengthening existing steel bridges is considering the possibility of adding load bearing deck above the main girders without replacing them. Converting alone metal section to composite cross-section raises the centre of gravity so that section can handle additional loads. In addition, the concrete deck may stiffen upper steel flange and thus eliminates the problem of stability of compressed part of the cross-section. In this paper the research on innovative rehabilitation method for the existing steel bridges is presented. The research has been performed within FP7 SMART RAIL project, and is based on the case study of rehabilitation project of the small non- ballasted steel bridge. The selected bridge (“Buna” bridge in Croatia) was built in 1893, with the first reconstruction in 1953. The bridge is about 9 meters long and 0.9 m high. Cross-section consists of two main girders made of hot rolled steel plates joined with rivets. Main girders are connected by horizontal and vertical grids for stiffening. Since the steel structure of the old Buna bridge will be completely replaced, the bridge is dismantled and transported to the laboratory for the experimental assessment and development of the new rehabilitation method. The new design will be based on the implementation of the prefabricated ultra-high performance fibre reinforced concrete (UHPFRC) deck, connected via welded steel headed dowels to the steel girder. It is expected that this strengthened cross-section will be able to withstand the increased load, as required by contemporary regulations.

Acoustic emission (AE) technique can be employed for determination (monitoring) of microcracking and cracking in concrete structure. As a preliminary study of a larger project concerning load resistance evaluation of reinforced concrete bridges, laboratory investigations on various reinforced concrete specimens have been performed. In this paper the results of an experimental study of the AE emission analysis and it’ s applicability for detection and monitoring of damage processes in reinforced concrete specimens subjected to load are presented. AE was used for identification of microcracking and cracking development during bond and flexural strength tests, performed on several series of reinforced concrete specimens. In the investigation plain and reinforced concrete beams (10x15x80 cm) were loaded in flexure up to the failure and recorded with AE technique. Further on, bond performance of reinforcing bars was tested according RILEM RC6 test and monitored by the AE techniques. In both tests (flexural and bond strength) the corrugated and smooth reinforcing bars were used, to investigate the difference in the mechanical behaviour and AE performance. The main purpose of this research is to investigate the applicability of AE technique on real structures, and to simulate “ new” concrete structures with mainly corrugated reinforcement, and “ old” concrete structures with mainly smooth reinforcement. During this investigation new experiences in AE monitoring of cracking in reinforced concrete specimens were gained. This study would allow more realistic damage assessment of concrete structures through monitoring of early cracking formation.

A strength of concrete increases with its age. The higher the strength of the concrete, the more brittle is its response. From the stress-strain curve of concrete with different strengths, it can be seen that the higher the compressive strength, the steeper is the slope of the descending part of the curve. However, effeciency of fibres in the FRC is increased too with the age, because of bond between fibres and hardened cement paste has improved. The results of our investigations are shown that toughness of SFRC decreases up to age of 28 days, and after that time it increases moderate. Toughness is measured and calculated according to the standard test methods of ASTM C 1018 and JCI-SF4.

Four different modes of bond between concrete (polymer modified steel fibre reinforced concrete (PM-SFRC)) layers are discussed in the paper. Wedge splitting test (WST) method was used to determine properties of bond: strength at limit of proportion, maximum strength and parameters for evaluation post-crack behaviour: ductility factor and modulus of toughness. They are compared with those of homogenous PM-SFRC. Maximumu strengths are compared with those determined with Pull-off test method.

4-year-old steel fibre reinforced concrete (SFRC) specimens were investigated to determine some parameters for evaluation post-crack behaviour of the HP-SFRC. Following parameters for evaluation post-crack behaviour of concrete were calculated from load- CMOD curves: absorption energy failure zone and equivalent strength at the appointed crack width. Three point bending congiguration was used to determine load-CMOD curves. The results of investigations show that high performance behaviour remain after 4 years only SFRC with steel fibres with aspect ratio of 100.

U radu su prikazani rezultati laboratorijskih istraživanja utjecaja betonu primiješanih vlakana na njegovu otpornost prema jednokratnom udaru i ponašanja pri statičkom opterećenju. Otpornost na udar vrednovana je s pomoću parametra žilavosti. Rezultati su uspoređeni s indeksiam žilavosti koji su određeni iz radnih dijagrama dobivenih standardnim statičkim pokusom na savijanje. Pokazalo se da su plipropilenska odnosno ćelićna vlakna višestruko povećala otpornost betona na udar.

Polymer cement steel fibre reinforced concrete (PC-SFRC) and steel fibre reinforced concrete (SFRC) specimens were tested according to WST (wedge splitting test) method. The age of concrete was 4 years. Specimens - cubes (10 x10 x10 cm) had initial notch length of 50 mm. During the test the load - COD (crack opening displacement) curve was recorded. But, due to fibres bridging the crack, it is very difficult to obtain complete area of the curve (absorption energy). Therefore, the load - COD curve is divided in four straight line segments, so that load decreases linearly to zero with increasing COD in the last segment. With such simplification, absorption energy of failure zone can be calculated as well as characteristic failure zone deformation. At the end, parameters for evaluation post-crack behaviour of PC-SFRC were calculated: ductility factor (1/B) and equivalent strengths up to crack widths of 0.1, 0.2, 0.3 and 0.4 mm. These parameters show improvement in the post-crack behaviour of SFRC when polymer is used.

Deliverable D5.3 “Performance evaluation of the solutions in real buildings in function of energy, durability, comfort respect to the European and national standards, codes and guidelines” presents the performance evaluation of the InnoWEE solutions installed in four demo site cases, real buildings in respect to their energy performance, influence on the comfort of the living environment and their durability.

Deliverable D5.3 “Performance evaluation of the solutions in real buildings in function of energy, durability, comfort respect to the European and national standards, codes and guidelines” presents the performance evaluation of the InnoWEE solutions installed in four demo site cases, real buildings in respect to their energy performance, influence on the comfort of the living environment and their durability.

Reinforced concrete is a widely used structural material. Usually, steel is the material used for reinforcing elements. Most important problem with using steel is the fact that it is susceptible to corrosion, which significantly affects durability of a structure. Fiber reinforced polymer (FRP) materials can be used instead of steel to avoid corrosion. FRP can either be used for repair of existing, or design of new structures. Different materials can be used to form FRP reinforcement, each having their own modulus of elasticity and strength, but all of them behaving elastically until failure. Usually, stiffness of steel is greater than stiffness of FRP bars, making FRP reinforced elements more sensitive to deflections. Hybrid FRP – steel reinforced members mitigate insufficiencies of both elements reinforced only with steel and elements reinforced only with FRP. Behaviour of hybrid reinforced members depends on not only the amount of each type of reinforcement, but also on its distribution inside a section. Since ductility of sections is important for overall structural response, a more detailed analysis of ductility is given in this paper. Different concrete sections with the same bending moment capacity are analysed. Only rectangular sections under bending moment are considered in this paper. Concrete class, width and height are all kept the same, while the rebar material, amount and layout are varied. Bending moment – curvature diagrams are obtained and compared with each other, as well as section stiffnesses.

To achieve the goals set by the European Union (EU) in terms of energy savings and decrease of the greenhouse gas emissions, the member states of the EU obliged that they would increase the number of the Nearly Zero Energy Buildings (NZEB). That increase has to be accomplished not only by building new NZEBs but also by deep energy renovations of old ones. One of the criteria to fulfil NZEB demands is to ensure the airtightness of the building, which is usually tested by an air pressurisation test. As there will be a great number of buildings which must undergo the testing in the near future, it is important to find a way to speed up the testing for the multizone buildings. This paper presents research based on the results of building zone airtightness estimations based on a fan pressurisation test by the so-called Blower Door system. It is a part of research whose goal is to develop a predictive model of the air-change-rate for a multizone building based on randomly tested zones. The paper describes a connection between the airtightness of tested building zones and elements which make up these zones. This research is crucial as a starting point for the development of the predictive model in order to define the parameters that affect these measurements. Statistical analysis was performed not only for the analysed results but also for an exploration of the connection between the zone elements and the zone’s airtightness as well. The paper presents a hypothesis based on the abovementioned research and proposes further research for the future development of the model.

The construction industry across Europe is facing major challenges in achieving energy efficiency targets, in particular for Near Zero Energy Building (NZEB), but they are also experiencing a digital revolution, with Building Information Modelling (BIM). The Fit-to-NZEB, Net-UBIEP (Horizon 2020) and BIMzeED (Erasmus+) projects intend to improve the human-capital basis of the construction sector, which is identified as a strategic initiative by the European Commission, acting on Higher Education Institutions (HEIs) and Vocational Education and Training (VET) systems in Europe. These projects support the construction industry, through education and training to upskill on technical innovation and digitalization. Not only is digitalisation trainings an important focus for the progression of the construction sector, but providing a low carbon efficient economy requires the integration of BIM with nZEB design and development approaches. At EU level, the challenge remains to introduce relevant standardised environmental and energy efficient learning topics into mainstream training and degree courses at HEIs & VETs. This paper analyses the current situation in the Architecture, Engineering and Construction (AEC) industry in several EU countries and provides a possible solution for the abovementioned problems in the field of NZEBs and BIM. The analysis of current formal and informal educational programs in the AEC industry revealed that topics related to the deep energy renovation (DER) and NZEBs are not adequately covered, or not covered at all, resulting with a lack of qualified workers and professionals. Another major problem detected in the conventional project delivering is an absence of integrated or interdisciplinary approach between all the stakeholders. This paper will show how the competences of construction stakeholders in the field of NZEBs and BIM can be increased.

It is now more obvious than ever that the only option for the development of the built environment is a sustainable and environmentally responsible one. In the field of building materials, especially in concrete technology, there are many studies that deal with alternative raw materials, such as by- products, recycled materials or natural resources that are not fully exploited. However, with the alternative materials, alternative durability challenges may also arise. More so, some of the known durability challenges may re-emerge in alternative forms. Alternative materials have different chemical and physical properties compared to a classical system. Different reaction products, different pore structure, electrical resistivity or tortuosity of the pores can lead to different behaviour of the materials and their degradation mechanisms. To predict and control the durability of alternative materials in the environment, a complete understanding of their microstructure is of utmost importance. In the present work, some examples of developed alternative binders based on local materials are presented. Among others, binders based on high cement replacement, binders based on calcium aluminate and alkali-activated binders are discussed. Among the degradation mechanisms, chloride penetration, corrosion and carbonation and their specific mechanisms with alternative binders are addressed.

Despite numerous national regulations, it has been shown that the traditional practice when insulating building envelope is insufficient if not enough attention is given to thermal bridges. Heat losses through thermal bridges are much higher than the heat losses through the surrounding area. Because of that, the thermal bridges are accompanied by lower surface temperatures, resulting in the higher risk of water vapour condensation and the formation of mould, and ultimately building damage. Therefore, much attention should be given to the design of thermal bridges and ultimately, its construction. This paper deals with the impact of thermal bridges on the outer building envelope of the ventilated façade system of the first ECO-SANDWICH® house in Croatia. The house is built in Koprivnica as part of the Green Zone project. It is designed according to the standards for passive houses using innovative, ventilated Eco-sandwich® façade panels, designed at the Faculty of Civil Engineering, University of Zagreb. All the details in this paper are modelled as two -dimensional, according to the HRN EN ISO 10211 standard. The numerical calculation is carried out by software specialised for the heat flow and thermal bridge calculation – Flixo. The output result, linear heat transfer coefficient (Ψ), which quantifies the impact of linear thermal bridges on the one -dimensional heat flow, is analysed by variation of parameters, such as thermal insulation thickness. Finally, the numerical results are compared with the results obtained by default values of linear thermal bridges according to the standard HRN EN ISO 14683. This comparison is made to show the error between the results obtained by the numerical calculation and the default values, which are typically taken in the traditional calculation of heat losses in buildings.

Polyurethane (PU) foams are widely used in building structures. Due to their good thermal and sound insulation properties, PU foams are often applied in the production of façade systems as a non-structural component. In addition, they are commonly used in structural load-bearing components, e.g. as a core material in composite sandwich panels. In order to be used in load-bearing structures, it is necessary to know their mechanical properties. The main mechanical properties of PU foams are influenced by many parameters such as density, temperature, anisotropy, loading condition, etc. In this paper, the influence of density on tensile and compressive properties of PU foam is presented. Therefore, the uniaxial tension and compression tests according to the International Standards for six different densities were performed. Based on the test results, the influence of density on tensile and compressive strength as well as compressive modulus of elasticity is reported.

In Croatia, a great number of buildings are built in masonry. The majority of them were built before the development of seismic codes and a lot of them are vernacular, unreinforced structures. As a result, many of these buildings need to be evaluated and, if needed, strengthened. Today, codes and guidelines for the evaluation and retrofitting of existing masonry structures do exist but are not very comprehensive and require a lot of engineering subjective judgment to implement. Furthermore, the problem lies in the complexity of implementing retrofitting methods since most of the masonry buildings are in use (private or public) during the strengthening. Besides that, a great number of buildings in Croatia (i.e. City of Dubrovnik) and around the world built in stone masonry have a great heritage value so the requirements made by conservators play a part in the methods used as well. An overview of the most commonly used methods of seismic analysis and strengthening are presented in this paper. The main objective of this paper is to comprehend, gather and compare different state -of-the - art principles of seismic retrofitting of structures focusing on stone masonry. Different approaches are analyzed and compared in order to get closer to a unified method of evaluation and strengthening of existing structures.

The topic of this paper is numerical modelling of concrete beams reinforced with FRP reinforcement and comparison of the results with experimental ones. Numerical models of concrete beams subjected to bending until failure, reinforced with steel, GFRP or CFRP reinforcement have been made. Thefinite element method was used, and the models were made in Midas FEA software. Concrete is modelled by the total strain crack theory. A smeared cracks model was used. Steel is modelled as Von Mises material, while FRP behaviour is linear elastic. The interface between the reinforcement and the concrete was also modelled, as bond – slip function. The goal is to compare the results obtained by numerical models with the results obtained by experiments, which were elaborated in previous work of first author. Experimental results contain material properties of used materials: concrete, steel and FRP reinforcement and bond slip behaviour between reinforcement and concrete. The results showed that it is possible to obtain similar results obtained by experimental research, but very important is knowledge of material behaviour and modelling of it.

In July 2019, Croatian energy market operator had 38 contracts for electricity from renewable energy sources (RES) with power plants under construction. 50% of these were for biomass power plants and represented 19% of planned install power. While the increasing number of plants creates more wood biomass ash (WBA) to manage, landfilling prices are rising and although this research is done locally, the problem is global. In 1882 the first coal fired power plant was built in London as a project by Thomas Edison. The first high-volume coal fly ash recycles in concrete was done to repair a part of the Hoover Dam in 1942. In the 80s, with first legal guidelines and construction expansion, recycling of coal ash in concrete become routine. Biomass has been used as heat energy since people learned to control fire, but when speaking about RES, we refer to modern biomass combustion systems that started to sprout in developed countries during the 90s. Extensive research on the characterization of WBA and its influence on concrete properties has been going on during the last few years. Research has also been done on the impact of recycling for other fields trying to find a quicker solution for ash disposal this time. For now, we know that WBA can be used as an active (replacement of cement) or inactive (filler, sand substitute) concrete component. Fly WBA is usually compared with coal fly ash, but ash properties vary depending on many factors - from type and growth conditions, through the combustion system, to ash management on site. The link between power plants and the concrete industry should be established through consistency and quality control. This could be achievable by establishing ash pre-treatments. Treated ashes could be a more reliable material for larger scale cement replacement.

Renewable energy, together with environmentally-friendly materials, gives us an insight into a sustainable future – one where reliance on fossil fuels and greenhouse gas emissions are minimised. The leading source of renewable energy in the EU are biomass fuelled power plants. Among different types of biomass, wood has the widest application while holding the majority share with 59% of all renewable energy sources. Nevertheless, combustion of 1 tonne of wood biomass generates approximately 3% of wood biomass ash (WBA), resulting in large amounts of waste. WBA management is an issue in need for prompt solutions, to avert further endangerment of the environment as well as disposal costs. Using WBA as partial cement replacement in cement composites is considered to be a feasible application. However, the fluctuating chemical composition of WBAs somewhat differs from coal fly ash, already acknowledged as a supplementary cementitious material. Due to the aforementioned difference and lack of standards and guidelines for WBAs application in cement composites, its wider application is still limited. Therefore, the main goal of this research was to quantify the acceptable amount of fly WBAs in concrete, while considering the chemical composition of different fly WBAs. Three WBAs utilized in this research were collected from different power plants located in Croatia, that exploit untreated wood chips as fuel while applying different combustion technologies. Six concrete mixtures were prepared with ash content of 15% and 20%. The impact of each WBA on concrete properties was analysed based on the determined compressive strength and modulus of elasticity. Differences between particular WBAs have been reflected on the properties of concrete mixtures.