Zoltán Gyurkó

• Doctor of Engineering
• PhD at Budapest University of Technology and Economics

This paper presents the study of a two-hundred-year-old, demolded solid clay brick using the rebound hammer test for the estimation of the compressive strength. During the test, the location and face type influence on the rebound values are monitored and recorded. In addition, the calculation of the average rebound value has been modified to encoun...

The present research deals with the cyclic and standard pull-out resistance of deformed steel bars embedded in lightweight and normal concrete. This paper is a continuation of a previous paper, where the experimental results are detailed. In the present paper, the experimental results are set against the formulas and the diagrams provided by the Eu...

The topic of present research is the experimental investigation of pull-out resistance of B500B-type ribbed reinforcing steel bars embedded in lightweight aggregate concrete (LWAC) under unidirectional cyclic loading. Only a limited amount of standardized data on bond strengths are available in the case of cyclic loading, especially for lightweight...

The present paper deals with the hardness of cement mortars prepared with recycled materials that are potential supplementary cementitious materials (SCM). Two potential SCMs (aerated concrete powder (ACP) and concrete powder) were investigated and compared with a reference (neat cement) sample and a sample containing metakaolin (MK). The long-term...

Present paper focuses on the modeling of size effect on the compressive strength of normal concrete with the application of Discrete Element Method (DEM). Test specimens with different size and shape were cast and uniaxial compressive strength test was performed on each sample. Five different concrete mixes were used, all belonging to a different n...

Present paper focuses on the modeling of size effect on the compressive strength of normal strength concrete with the application of discrete element method, considering specimen of different concrete mixes and shapes. An equation was derived to estimate the parallel bond strength from the compressive strength. The results showed a good agreement w...

Present study deals with the effect of size and shape on the compressive strength of concrete. Mixes of five different strengths were designed, all between C20/25 and C50/60 strength class (normal strength concretes). Different size specimens were casted from all mixes in cube (edge length: 50 to 200 mm) and in cylinder (diameter: 60 to 150 mm) sha...

Traditional supplementary cementitious materials (SCMs), like metakaolin or microsilica, highly improve various properties of concrete, making it more resistant against the effects of the environment. However, the cost of concrete is highly influenced by the applied amount of SCMs. Cellular concrete powder (CCP) is a by-product, produced by the cut...

It is a challenging task to take into account the type and form of aggregate in the numerical modelling of concrete. Discrete Element Method (DEM) offers the possibility to consider these properties via its model parameters. However, to get a usable model for further purposes, these model parameters first have to be calibrated precisely, based on l...

In the next decades many buildings and structures, constructed from autoclaved aerated concrete (AAC) will reach their end of lifetime, therefore solutions should be developed to recycle the resulting waste material. AAC blocks cannot be reused in the form of building blocks as traditional clay bricks. The typical form of AAC waste is crushed stone...

Present paper focuses on the static hardness testing of porous construction materials. A series of experiments were conducted by the authors, during which the main strength properties of twelve different construction materials (normal and high strength concrete, concrete with supplementary cementing materials (SCM), limestones, ceramics, polymer co...

Discrete Element modelling of concrete requires the precise calibration of model parameters that is a long lasting and computationally expensive task in case of complex models. Present study introduces a method for estimating a model parameter (normal strength of parallel bonds) for concretes with different particle size distribution and aggregate...

Present research program is dealing with the effects of cellular concrete powder (CCP) on the compressive strength and durability of concrete. CCP is an industrial by-product, which was applied as supplementary cementitious material (SCM) in the concrete mix. In the previous research of the authors of this paper, it was found that the cellular conc...

The aim of our research project was to investigate the effect of different construction waste materials on the strength and durability of normal concrete. Construction waste materials were applied as supplementary material. 10% by mass (relative to the cement amount) of cellular concrete powder or powdered clay brick were used in the mixes, which w...

Present research program is dealing with the effects of cellular concrete powder (CCP) on the compressive strength and durability of concrete. CCP is an industrial by-product, which was applied as supplementary cementitious material (SCM) in the concrete mix. In the previous research of the authors of this article, it was found that the cellular co...

Present study deals with the static hardness testing of normal-strength concrete and with the Discrete Element Method (DEM) modelling of hardness testing methods to have a better understanding of the behavior of normal-strength concrete under a penetrating spherical body. Discrete Element Method is a powerful tool to model porous solid materials li...

A keménységmérés az első eljárás volt az anyagok mechanikai tulajdonságainak vizsgálatára. Definíciójának meghatározására több megfogalmazást is kidolgoztak már a múltban, ezek közül a legpontosabb talán a következő: keménység fogalma alatt az anyag ellenállását értjük a beléje hatolni szándékozó keményebb testtel szemben. A keménységmérés során a...

The aim of this study was to investigate the contact phenomenon between solid bodies, in case of porous stone-like materials. Experimental investigations were modelled with the help of a discrete element modelling software. Discrete element method is a numerical approach, which is very advantageous in case of granular materials to observe the chang...

Present paper deals with the Brinell-hardness testing of hardened concrete and with the Discrete Element Method (DEM) modelling of this type of experiment to get a better understanding of the behaviour of porous solid materials under a penetrating spherical body. Discrete Element Method is a powerful tool to model porous solid materials like concre...

In the present study Brinell macro hardness tests and Depth Sensing Indentation tests were performed on hardened concrete specimens and the results were compared with a discrete element model, created by the authors of this paper. The results of the investigations have demonstrated the satisfactory use of discrete element modelling with a good corr...

Hardness testing is considered to be the earliest method of material testing. For the measurement of hardness of stones and other porous solid materials mostly dynamic testing devices are applied in practice, however for scientific purposes indentation hardness tests are more suitable methods. In present research Brinell macro hardness tests and de...