György L. Balázs

Budapest University of Technology and Economics · Department of Construction Materials and Engineering Geology

The present chapter discusses the following aspects of reinforced and prestressed concrete bridges: material specifications (US and European standards); different types of cast-in-situ or precast bridge decks like solid or voided slabs; beams; reinforcing and prestressing systems; details; losses and time-dependent effects in prestressing; design c...

This paper presents a review of 3D printing technology in medical application, materials used in 3D bioprinting, benefits, challenges as well as the future of additive manufacturing in medicine. This technology is going to revolutionize medicine, the flexibility of 3D printing allows designers to make changes easily without the need to set up addit...

Digital production has been applied in many branches of the industry; however, the construction industry was an exception. Applying this new technology could help to reshape the construction world as we know it today. Using 3D printing technologies in construction offers significant potential to increase efficiency in terms of speed construction, w...

Concrete is the second frequently used material in our planet. Being the most consumed construction material for infrastructures and buildings, the demand for concrete is very high at present and expected to have the same significance in the future. On the other hand, conventional concrete could not be considered as an environmentally friendly cons...

The 3D printing technologies have been initially developed in the 1980s. Currently, these technologies have become an integral part of modern product development and have been successfully applied in a wide range of industries including automotive manufacturing, biomedical, consumer, food, and construction. Since material efficiency is becoming a c...

This Chapter provides a detailed better understanding of the freeze/thaw effect on concrete, it is discussing the attack mechanism for both types of freeze/thaw deterioration: Internal frost damage and Surface scaling. Freeze/thaw attack is a serious problem for concrete but the most common physical deterioration type that shortening the life of co...

The combined use of Fibre Reinforced Polymer (FRP) and Air-Entrained Concrete (AEC) can be an alternative to traditional steel-reinforced concrete as this system is less affected by the corrosion of the reinforcement and by the freeze-thaw cycles induced concrete degradation. However, the viability of this system hinges on the bond performance of t...

The precasted and prestressed beams with CFCC strains - how can we cast it?

Bond performance of Fibre Reinforced Polymer (FRP) bars to concrete can considerably differ from those of traditional steel because of the different physical and mechanical properties. The surface of FRP bars is most often greatly different from the ribbed shape of steel bars. This study focuses on the influence of surface type on the bond characte...

ÖSSZEFOGLALÁS Konzorciumi kutatócsoportunk olyan fejlesztési területeken vállalt közös erőfeszítéseket, amelyek a környezetünket jelentősen meghatározó vasbetonszerkezetek biztonságosabb és hosszabb élettartamú használatára nyújtanak lehetőséget, erőforrásaink hatékonyabb kihasználása mellett. Törekvéseink elsődleges célja olyan betonösszetételek k...

A XX. század végei gyártástechnológiák gyors fejlődése új gépek és technológiák megjelenését is eredményezte. Ezek közé tartozik az 1980-as években megjelent 3D nyomtatás is. Néhány évvel ezelőttig ez a technológia csak prototípus előállására alkalmas gyártási folyamat volt. Azonban a 3D nyomtatók 2010-es évek elején szélesebb körű elterjedése lehe...

This paper presents an extensive experimental study of the effect of surface characteristics on the bond behaviour of Fibre Reinforced Polymer (FRP) bars in concrete. A wide range of commercially available FRP bars with different surface profiles (total of 13 different surface configurations) were involved. For comparison, ribbed steel bars were us...

A betonok fagy-, illetve fagy- és olvasztósóállóság-vizsgálati hámlása időben lejátszódó folyamat, amely lassuló vagy gyorsuló jellegének korábban nem túl sok figyelmet szenteltünk. A hámlasztásos fagyasztási lassulás is viszonylag új fogalomnak tekinthető, amely fogalom ilyen elnevezésének a nemzetközi irodalomban sem találtuk a nyomát. E cikkben...

Shear investigations are important in concrete due to the nature of brittle failure of shear. Moreover, concrete structures are more prone to shear failure in case of elevated temperatures. An experimental program has been investigated herein using different amounts of steel fibres, i.e., 0, 40 and 80 kg/m3. This study is part of overall study for...

The article presents the results of an extensive experimental study focused on the effect of supplementary cementitious materials (SCMs) on concrete thermal properties. In case of normal weight concrete (NWC) and three types of lightweight aggregate concretes (LWAC), made with 6 different types of cements, the heat transfer properties of the concre...

A 3D nyomtatás a megjelenésétől fogva az érdeklődés középpontjában van. A technológia fejlődésén és sikeres alkalmazásain keresztül életünk részévé vált a legkülönbözőbb területeken. A folyamatok összetettsége révén a betonnyomtatás van talán a többi területhez képest (műanyagnyomtatás és fémnyomtatás) leginkább lemaradva. Szándékunk ezért részlete...

Glass Fibre Reinforced Polymer (GFRP) bars have been employed as internal reinforcement for concrete members when corrosion of the commonly used steel bars is expected to be an issue. While a good bond is anticipated between GFRP bars and concrete at ambient temperature, the bond performance at high temperature is expected to be reduced due to the...

An extensive experimental work has been performed to study the effect of air-entraining admixtures (AEA) on the bond behavior of FRP bars in concrete. The experimental program was designed to study the effect by using different test setups (traditional and modified pull-out tests), four concrete mix designs (range of compressive strength: 35 to 77...

Purpose of study of internal structure of materials – both with optical microscopy and scanning electron microscopy – is to find explanations for stress and deformation properties as well as cracking in the material based on internal properties, bond and interaction of components. Scanning electron mi-croscopy provides observations for both in micr...

GFRP (Glass Fibre Reinforced Polymer) reinforcing bars find recently increasing application in RC (Reinforced Concrete) structures. In addition to the main advantages, such as non-corrosive nature and high strength-to-weight ratio, the main drawback is their endurance under high temperature. Mechanical properties of GFRP bars and their bond to conc...

A megszilárdult betonnal, betontermékkel, vasbeton és feszített vasbeton szerkezeti elemmel érintkező lágyvizek és agresszív vizek, folyadékok, gázok, gőzök, permetek, erjedő anyagok a cement kötőanyagú betonok oldódásos korrózióját okozhatják. Cikksorozatunknak e folyóirat 2017. évi 3. számában megjelent 1. részében (Balázs et al., 2017) a vizek é...

Glass Fibre Reinforced Polymer (GFRP) bars became an alternative to that of traditional steel as internal reinforcement of concrete structures especially when their electrolytic corrosion resistance is important. GFRP bars show superior mechanical properties and have low weight (density). However, the bond behavior and bond strength of GFRP bars in...

Nowadays X-ray computed tomography (CT) imaging is being applied in the field of structural engineering. Scanning a concrete specimen by using X-ray tomography provides an insight into the inner structure without the need to destroy the specimen. As an example, the internal structure of cement-based materials is of high importance for understanding...

Fibre Reinforced Polymer (FRP) bars provide an alternative solution to that of steel reinforcement, especially whenever the corrosion resistance is of high importance. To ensure the composite behaviour between FRP bar and concrete, adequate interaction must be mobilized. Bond behaviour of FRP bars in concrete can be significantly different from tha...

Composition and microstructure of hardened cement paste have important influences on the properties of concrete exposed to high temperatures. An extensive experimental study was carried out to analyse the post-heating characteristics of concretes subjected to temperatures up to 800 °C. Major parameters of our study were the content of supplementary...

This is a Congress Proceedings with important information on innovations in concrete on composition, reinforcements, characteristics, design and applications

An extensive experimental study has been carried out to analyse the post-heating characteristics of concrete subjected to high temperatures up to 800 °C. Major parameters of our study were the type and amount of supplementary cementitious materials (slag, fly ash, trass, silica fume, metakaolin) in cements and the level of maximum temperature (50,...

Synopsis: This paper presents an extensive experimental study of the effect that the surface profile has on the bond behavior of FRP bars in concrete. Studied parameters include: concrete strength (~35 MPa (5075 psi) and ~66 MPa (9570 psi)), test type (pull-out, direct tension pull-out and beam pull-out) and surface profile of the FRP bar (helicall...

Exposure of reinforced concrete elements to elevated temperature can significantly affect the bond behaviour of embedded reinforcing bars. When FRP bars are used in lieu of the more conventional steel, their bond performance is expected to reduce due to the change in the properties of the resin matrix and there is a strong consensus that FRP bars s...

Synthetic reinforcements in concrete structures are becoming more wide used because of their most important advantage to be resistant against electrolytic corrosion. The fibre reinforced polymer (FRP) bars can increase the beam’s capacity as main reinforcement and as stirrups. Macro synthetic fibres can increase the ductility of the elements and th...

Durability and service life of concrete structures can be endangered by chloride ions. Two phenomena help to keep control of chloride effects. On one hand cements are able to bind chloride ions by their aluminate clinker phases or by the clinker substituting materials. On the other hand resistivity of concrete against chloride penetration can be im...

Nowadays application of fibre reinforced concretes (FRC) becomes more and more widespread, due to the favourable experiences with their behaviour. As a consequence, an increasing number of studies are published on different aspects of FRC. Several scientific papers indicate the importance of homogeneous distribution of fibres. Our study includes an...

Fire can cause damage in structures. The level of damage depends on several factors, such as maximal temperature, duration of fire, constituents of the concrete and so on. It is necessary to design fire-resistant buildings and deal with possible reconstruction after fire. For the reconstruction, it is important to determine the level of damage and...

Our study was directed to the analysis of the influence of various types of cements on the behaviour of concrete at high temperatures. In our experiments binary blended and ordinary Portland cements were involved: two Portland cements with different clinker compositions and Portland cements containing pozzolanic additives as replacement of clinkers...

Synthetic reinforcements in concrete structures, such as macro synthetic fibres and fibre reinforced polymer bars are becoming more wide used nowadays, because of their most important advantage to be resistant against electrolytic corrosion. The fibre reinforced polymer (FRP) bars can increase the flexural capacity both as main reinforcement and sh...

Az utóbbi évtizedekben számos épületkatasztrófa igazolta, hogy a tűzteherre való méretezés kérdései továbbra is aktuálisak. A különböző hőmérsékleti tartományokban a betonban lejátszódó legfontosabb fizikai és kémiai folyamatok jelentősen befolyásolják a beton magas hőmérséklet hatására kialakuló anyagtulajdonságait. A beton tűzterhelés hatására be...

The present chapter intends to include the following aspects for reinforced and prestressed concrete bridges: material specifications (US and European standards); different types of cast-in-situ or precast bridge decks like solid or voided slabs; beams; reinforcing and prestressing systems; details; losses and time-dependent effects in prestressing...

Our study was directed to improve the residual flexural strength and the heat-resistant properties of concrete exposed to high temperatures using different fiber cocktail loadings including steel, polymer or cellulose fibers. At first the morphology and the thermal properties of the fibers and the fiber/cement composites were investigated by SEM an...

Existing bond models for FRP reinforcements are based on limited number of parameters only. Present study includes the description of an extensive experimental work, as well as an analytical part for modelling the bond behaviour of FRP rebars in plain and in fibre-reinforced concrete. Experimental parameters consisted of: (1) type of FRP rebar (car...

Properties of fibre reinforced concrete (FRC) are mainly influenced by type and amount of fibres. Fibre properties are defined by the fibre producers. However, the properties of hardened FRC are influenced by the properties of fibres after mixing. Fibres are often added to the concrete in the concrete plant during mixing or immediately after the co...

Composition and microstructure of hardened cement paste have important influences on the properties of concrete exposed to high temperatures. An extensive experimental study was carried out to analyse the post-heating characteristics of concretes subjected to temperatures up to 800 °C. Major parameters of our study were the content of supplementary...

Different fibers induce different improvements in concrete properties. Fiber cocktails may contribute to provide improvements in different phases of behavior and for different effects (loads or high temperatures). First group of our experimental study included flexural tests in CMOD control with the mix of either two types of steel fibers (short pl...

Favorable experiences with fiber reinforced concrete (FRC) resulted in its growing use worldwide. The properties of FRC are mostly influenced by the fiber type and fiber content. Almost all of the mechanical properties of FRC depend on the tensile strength and the modulus of elasticity as well as the geometrical properties (bond) of fibers. Steel f...

Favourable experience with fibre reinforced concrete (FRC) resulted in its increasing use worldwide. The properties of fibre reinforced concrete are mostly influenced by the type and the amount of fibres. Our experimental study was directed to the possible improvements of the residual flexural strength and the properties of concrete exposed to high...

Favourable experience with fibre reinforced concrete (FRC) resulted in its increasing use. There is a large variety of fibres that can be used in concrete. Properties of fibre reinforced concrete are mainly influenced by the type and the amount of fibres. Demolishing unserviceable concrete structures provide a large amount of recycled aggregates al...

Application of FRP (Fibre Reinforced Polymer) bars as internal reinforcement can increase durability of reinforced and prestressed concrete structures. If short fibres are mixed into concrete a better confine-ment of concrete in compression is provided as well as a more reasonable use of FRP bars in the ten-sion zone can be reached. It is important...

The postcracking behavior of fiber-reinforced concrete (FRC) is mostly influenced by the type of fiber, the amount of fibers, fiber orientation, and the concrete strength. Manufacturers of fibers propose a minimum mixing duration after fibers are added to concrete to obtain an acceptable dispersion of fibers. What about the maximum mixing time? Fib...

Szálerősítésű betonok nagyobb alakváltozó képességgel rendelkeznek, mint a szokványos, száladagolás nélküli betonok, ami előnyt jelent, ha a szerkezeti elemekben fellépő húzófeszültségeket a viszonylag alacsony rugalmassági modulussal rendelkező FRP betétekkel szeretnénk biztosítani. A vasbetonszerkezetek esetén elengedhetetlen az erők átadása beto...

Concrete is a composite material that mainly consists of mineral aggregates bound by the matrix of hardened cement paste. Composition and microstructure of hardened cement paste have important influences on the properties of concrete exposed to high temperatures. An extensive experimental study was carried out to analyse the post-heating characteri...

p>Deterioration of material characteristics and structural performance highly depends on constituents and temperature history. Material composition can also highly influence structural behaviour of elements. Thickness of web can be critical for high temperatures. The same situation is for interjoist elements (concrete or brick) between precast roof...

Synthetic reinforcements in concrete structures, such as macro synthetic fibres and fibre reinforced polymer bars become more popular nowadays, because of their most important advantage: the resistance against electrochemical corrosion. The fibre reinforced polymer (FRP) bars can increase the flexural capacity, and the macro synthetic fibres can in...

Residual tensile strength of fibre reinforced concrete (FRC) is one of the most important parameter both for design and for practice. Appropriate method and mixing time are required to reach random distribution of fibres and acceptable properties of concrete. Properties of FRC are mostly influenced by the fibre type and the amount of fibres. Fibre...

Favourable experiences with fibre reinforced concrete (FRC) resulted in its increasing use worldwide. Most of the natural fibres have relatively high tensile strength, however, their long term alkaline resistance should be also provided. Present study was directed to measurements on the hemp fibres with two different coatings as well as on concrete...

Application of Fibre Reinforced Polymers (FRP) had increasing significance over the last decades for strengthening reinforced concrete (RC) structures. In NSM (Near Surface Mounted) strengthening technique the FRP material is bonded into grooves cut in the concrete cover. This technique has been living its renaissance since the end of the 90’s. In...

Application of fibre reinforced polymers (FRP) reached increasing significance over the last decades for strengthening reinforced concrete (RC) structures. However, the growth in the use of FRP reinforcement as internal reinforcement is less impressive. There are few reasons of this, the most important ones are: the relatively high price of the FRP...

Despite the extensive research on the debonding behavior of fiber-reinforced polymer (FRP) strengthening systems, no standard methodology has been established on its experimental characterization. To assess the performance and reliability of small-scale testing on near-surface mounted (NSM) FRP strengthening systems, an experimental program was car...

Overall 360 km Sentab type prestresed concrete high pressure water pipes were installed in Hungary. They were longitudinally and spirally prestressed by steel prestressing wires during production. These pipes provide a very important part of the water supply system of the capital city and numerous other cities in Hungary. Our studies were directed...

Favourable experience with fibre reinforced concrete (FRC) resulted in its increasing use worldwide. The properties of fibre reinforced concrete are mostly influenced by the fibre type and the amount of fibres. Fibre properties (tensile strength, length, surface characteristics, shape and density) are normally defined by the fibre producers. Howeve...

HPC and UHPC concretes are finding their ways both to new structures and to retrofitting of existing structures. Herein specific material properties as well as structural examples are discussed. New Codes and Recommendations provide description of material properties and design rules for HPC/UHPC structures and structural elements.

This paper intends to summarize the behaviour of the FRP rebars in concrete for direct pull-out and beam type test conditions, furthermore it also gives a brief overview of the material characteristics and the bond mechanism between FRP rebars and concrete. In normal strength concrete, the mode of bond failure of FRP rebars was found to differ cons...

The system of bond stresses for force transfer between reinforcement and surrounding concrete is the basis of the existence of reinforced concrete. Without a proper transfer of stresses between concrete and reinforcement, reinforced concrete structures would not be feasible without end anchorages. In order to construct more durable reinforced concr...

A vasbetonszerkezetek esetén elengedhetetlen az erők átadása beton és a beágyazott betét között. Vasbetonszerkezetek beágyazott (acél, ill. nem acél anyagú) betéteinek a tapadása és együttdolgozása meghatározó jelentőségű a szerkezeti elemek teherbírása és használhatósága szempontjából. Az acélbetéteknél tapasztalható korróziós károsodások miatt me...

Az acélbetéteknél tapasztalható korróziós károsodás miatt megjelentek a nem acél anyagú betétek, amelyeknél az elektrolitikus korrózió kizárt. A vasbetonszerkezetek esetén elengedhetetlenaz erők átadása a beton és a beágyazott betét között. Vasbetonszerkezetek beágyazott (acél, ill. nem acél anyagú) betéteinek a tapadása és együttdolgozása meghatár...

In Hungary the production and application of the Sentab water pipes started in 1969. These pipes have a very important part in the water supply system of Budapest and numerous other places. Overall 360 km Sentab type water pipes were installed in Hungary. In our research we analysed the production technology of the water pipes, to locate the main p...

Present concrete technology requires fast execution and reliable material properties. Recent efforts concentrate on possible use of fibres for structural purposes. We discuss 3 examples for application of polymeric fibers: (1) The first example is the increasing of fire resistance thin webbed prestressed concrete roof girder. (2) The second example...

Overall 360 km Sentab type water pipes were installed in Hungary. Due to the significant diameter the Sentab water pipes were used as parts of the main water lines, so it is very important to prevent any failure. In our research we studied the production technology of the water pipes, to locate the main cause of the deterioration. We carried out no...