Zdeněk Prošek

• Ph.D.
• Czech Technical University in Prague

In this study, we explored and described various parameters of microbially induced calcite precipitation (MICP) using the alkaliphilic bacterium Sporosarcina pasteurii DSM 33, which exhibits ureolytic activity, to stabilize and strengthen waste concrete fines (WCF). Bacterial cell concentration, single and repeated addition of bacterial suspension,...

This research work deals with the issue of laboratory testing of commonly available recycled fine aggregates, namely concrete recyclate, mixed recyclate and brick recyclate. Their geometrical properties: granulometric composition and fine particle content, including physical properties: bulk density and water absorption are investigated. The tests...

The paper deals with the investigation of alternative binders, namely the two available samples N6 and N7 with comparison from the reference sample CEM I 42.5R. Both testing binders are provided by company Destro. It is a product that contains different ratios of fly ash and slag. By examining the properties, the mix was compared in different propo...

The study delves into the impact of waste silicon-based materials on the mechanical characteristics of the resulting cement pastes. The investigation uses Portland cement CEM I 42.5R in conjunction with silicon-based waste materials sourced from the packaging industry, specifically from Recifa, a.s. Variations between the sample groups arise from d...

Waste glasses based on silicon dioxide (silica) belong to one of the most demanded secondary raw materials. Besides the glass industry, with strict requirements for source materials, silica-based granular materials from waste glasses are considered suitable for use as fillers in alkali-activated cement-based composites. However, due to variations o...

One of the ways to use the treated gypsum waste is in gypsum mixtures for the production of gypsum blocks. Gypsum blocks can be used in standard interior as well as exterior applications and are made of gypsum, water, PP microfibres and are lightened with foam, which is created from a foaming additive and water. Above all, the amount of foam signif...

The effect of atmospheric and low-pressure plasma modification on polypropylene (PP) microfibers was examined. Mechanical changes on the microfiber surfaces were observed using scanning electron microscopy (SEM). Next, wettability was measured using the packed-cell method. The fibers were applied into a cement matrix containing micro-milled recycle...

A significant body of research has been carried out to find suitable waste materials or industrial by-products that could replace portland cement and reduce the environmental footprint of the concrete industry. Many studies focus on technical aspects, lacking an assessment of environmental impacts associated with using these alternative materials,...

Air pollutants, such as nitrogen oxides (NO and NO2), have a negative impact on the built cultural heritage. In order to reduce it, a photoactive repair plaster for conservation of various gypsum decorations, in particular moulded elements, has been developed in compliance with the requirements of conservators-restorers international community. Hen...

Titanium dioxide (TiO2) is used as a UV light absorber to protect wood matter from photodegradation. In this paper, interactions between wood and TiO2 coating are studied, and the efficiency of the coating is evaluated. For the experiments, two wood species were chosen: beech (Fagus sylvatica) and pine (Pinus sylvestris). Molecular and physical mod...

Cracks on the surface of cementitious composites represent an entrance gate for harmful substances—particularly water—to devastate the bulk of material, which results in lower durability. Autogenous crack-sealing is a significantly limited mechanism due to a combination of the hydration process and calcite nucleation, and self-healing cementitious...

Different strains of bacteria capable of calcite precipitation can be incorporated into fresh concrete or cement mortars to efficiently promote self-healing of microcracks after hardening. To date, all bacterial strains investigated have required protection against the highly alkaline environments and high pressures in cementitious matrices. The co...

The article introduces possibility how to use special material from plasterboard back to the production of plasterboards. The recycled material was prepared from standard plasterboards KNAUF WHITE (it means plasterboard type A according to European standard EN 520) [1]. Plasterboards were crushing, micromilled and separated from the paper on recycl...

The article focuses on sulphate corrosion of cement pastes with a high content of waste micronized marble powder. Micronized marble powder is used as a substitute for Portland cement CEM I 42.5R. The amount of micronized marble powder used is from 5 to 50 wt. %. The research also tested a reference mixture composed only of Portland cement. The used...

The construction elements produced with low demand for primary resources are being developed in the building industry. However, not only consumption of primary resources but also environmental impacts of such products should be considered to increase the sustainability of the construction industry. To investigate the environmental impacts of lightw...

Mineral wool is one of the most commonly used types of thermal insulation in the European Union at the present, however, it generates massive amounts of waste. From an environmental standpoint, recycling or reuse of insulation materials seems to be a wise solution. This paper aims to study the thermal and structural properties of recycled mineral w...

The surface treatment of polypropylene microfibers by plasma processing in oxygen and argon was studied with the motivation to increase their cohesion with the cement matrix. By plasma treatment, it is possible to modify the surface of the microfibers mechanically, chemically or with a combination of both. The microfibers were modified using the re...

It has become increasingly clear, that the recent consumption of mineral resources is unsustainable. The Czech Republic produces more than 217,000 tones of mineral wool annually, while its recycling stays unacceptably limited. This paper presents new possibilities how to recycle mineral wool from building insulation systems. Cladding of 30 years ol...

This paper outlines prediction of the macroscopic response of unidirectional fibrous composites made either from basalt or carbon fibers impregnated by a polymeric epoxy matrix. The viscoelastic response of the matrix phase was represented by the Maxwell chain model. A series of creep tests performed at several stress levels served as a stepping st...

The article deals with durability of wood, durability of wooden structures and surface modification of wood. We are trying to eliminate the factors causing degradation of wood with the use of photocatalytic materials. Those materials are efficient UV absorbers and they are able to destroy biological aggressors also. The planar particles of titanium...

External wooden structures have own place in the building industry for ages. The problem is that wood easily degrades due to UV radiation, atmospheric conditions and biological aggressors. We are trying to eliminate degradable factors by photocatalytic materials (namely titanium oxide). Those materials are efficient UV absorbers and they are able t...

The usage of waste materials is a very important global topic. The large amount of waste everywhere in the world needs to be processed or disposed. Landfilling is not an option anymore, because of European legislation and restrictions. A lot of studies are trying to develop new options or possibilities of using waste materials. This research is try...

This article is focused on detection microorganisms appearing during production of gypsum plasterboards. The research is carried out within the project TAČR ZÉTA TJ02000235 Sádrokarton se zvýšenou odolností proti bilogické degradaci (Gypsum plasterboard with increased biodegradation resistance). This article shows first part of this issue what was...

The reuse of old concrete as a coarse and fine recycled aggregate in cement composites is relatively well researched, and therefore a very fine fraction of recycled concrete was used in this paper. When using a very fine fraction of recycled concrete, it is appropriate to focus primarily on less technologically demanding treatment processes with mi...

The article focuses on the effects of additives increasing biological resistance of gypsum against degradation of the material. In this study we use silver nitrate, calcium oxide and copper sulphate as an additive that improves biological resistance of gypsum composites. The amount of addition was calculated so that the amount of ions was 0.1, 0.3...

The article deals with the optimalization of composition for reinforced lightweight cement composite containing micronized recycled concrete, which will be used to produce masonry blocks. The composite material is reinforced with polypropylene microfibers. To increase the cohesion between the fibers and the cementitious matrix, the optimal modifica...

The paper deals with the determination of nano, microstructural, and micromechanical properties of cementitious materials surface with self-healing agent based on calcium carbonate precipitation (calcite). This was done by means of electron microscopy with elemental microanalysis and nanoindentation. These methods can define parameters of individua...

Self-healing processes in cementitious materials have been intensively studied in recent years. They present a promising way to increase the durability of concrete and extend the service life of concrete structures, thus mitigating the impacts of the construction industry on public budgets and the environment. The role of bacterially induced calcit...

The developing nanotechnology is getting infiltrated into a wide area of industries. A variety of nanotextiles can be produced from different materials (e.g. polymers, SiO2). Their applications are possible in many industrial branches as well as civil engineering. Silica-based nanotextiles can play a fundamental role in civil engineering. The poten...

Poor adhesion of synthetic macro fibers to a cementitious matrix limits their reinforcing capacity when used in fiber-reinforced cementitious composites (FRCCs). As a remedy to this problem, high concentrations of fibers must be incorporated into such mixtures, which makes their dispersion in fresh mixtures difficult to achieve. Several strategies...

Several researchers have considered waste marble sludge (WMS) as an admixture to cementitious composites. However, the scientific community is divided into two groups—one advocating WMS as a suitable microfiller, while the other claiming that WMS inhibits hydration of clinker minerals. Here, the role played by WMS during Portland cement (PC) hydrat...

The advantages of supplementary cementitious materials (SCM) use in concrete, such as reduced cement consumption and overall material improvement (durability, chemical resistance, etc.), are widely known. Our research focuses on two major factors connected to high performance concrete (HPC) containing SCM, the content of selected SCM and the homoge...

Cracks affect the durability of concrete by increasing its permeability. Self-healing materials can begin repairing themselves immediately after creating a crack. This is a big advantage of self-healing materials. In this study, effect of self-healing agents based on calcium carbonate precipitation for concrete is monitored for three months. Bacill...

The costs of construction waste handling, a scarcity of landfill sites, and requirements for sustainable construction have placed recycling of concrete-the most abundant construction material in the world-under scrutiny. Unlike recycling of aggregates, utilization of sub-sieve fractions from recycled concrete has not yet been adopted in the constru...

The article deals with the selection of a suitable hardening accelerator for cement composite material for mass production of masonry blocks. The blocks contain cement and finely ground recycled concrete in ratio 1:1. Three different hardening accelerators in different quantity were tested for possibility of fast removing formwork. The dynamic modu...

The article presents the first results from research, which is deal with recycling of plaster boards and use of the resulting material. The research is carried out within the project MPO Trio c. FV30359 “Recyklace sádrokartonových desek a nová materiálová využití s pridanou hodnotou – GIPSRec”. The plasterboards are produced of stucco, which is cal...

The article focuses on the impact of different type of mixing approach on resulting mechanical properties of cement composites. The monitored parameters of the mixing approach were the speed of mixing and the method of mixing the individual components of the fresh mixture. The mechanical properties of the resulting composites were the main comparat...

Recycling of materials is very popular and very important in these days. Finding the new ways to process and use these materials is a key to get rid of a lot of construction waste. The amount of landfilling needs to be reduced. This study observes mechanical properties of the cement composites containing recycled concrete powder and alkali-activate...

The current theme of recycling waste materials incl. waste from construction brings many challenges and issues associated with this effort. The paper deals with finely milled recycled concrete, which could serve as a partial substitution of cement, and its natural moisture, which in conjunction with other material characteristics, can influence the...

This paper is focused on the bacterial induced calcitation for the crack healing. The bacteria applied for this purpose are from group which is adapted for growth in the high pH environment as a concrete in hydration phase and their metabolic activity leads to create of calcite. In this study, three different bacteria strains (Sporosarcina pasteuri...

Microscopic Studies of Irradiated Wood by UV light - Volume 25 Supplement - Petr Svora, Sylwia Svorová Pawelkowicz, Zdeněk Prošek

Fiber reinforced concrete mechanical properties are limited due to low adhesion between polymer fibers and cement matrix. To ensure a strong interaction between the two materials, polypropylene fibers (d = 0.305mm) were modified by an oxygen plasma treatment. The interface interaction was moreover activated using finely ground concrete recyclate, w...

This paper deals with the use of high-speed milling process for recycling old concrete and direct determination of the potential of input waste. For this purpose, three different types of waste concrete were used: prefabricated railway sleeper, structural concrete of monolithic pillar and prefabricated drainage gutter. The paper directly examines t...

Even though the corrosion of steel in concrete is very well described, the corrosion processes in lime environment studied very rarely. This environment is obviously also basic and its pH decreases in time, but the obtained results indicate important differences in behaviour of these two systems. Corrosion response of carbon steel, zinc platted ste...

The paper describes an experimental program focused on the research of high performance concrete with partial replacement of cement by fly ash. Four mixtures were investigated: reference mixture and mixtures with 10 %, 20 % and 30 % cement weight replaced by fly ash. In the first stage, the effect of cement replacement was observed. The second phas...

Alkali activated fly ash is a widely used admixture to the concrete. Due to the pozzolanic activity, the fly ash can replace up to 60 mass percentage. The impact of fly ash on the concrete depend on the level of it content, i.e. in small levels it improves the macro-mechanical properties and durability as well as chemical resistance. On the other s...

The article describes plasma modifications of the surface of polyvinyl alcohol (PVA) microfibers using oxygen and hydrogen plasma in order to improve the properties of the composite material containing modified microfibers, cement and recyclate. Five different modification times 30, 60, 120, 240 and 480 seconds were applied. Changes on fiber surfac...

This article discusses the possibility of recycling of concrete waste using the high-speed milling method. The resulting of milling is micronize old concrete. Used old concrete was created by crushing of old concrete, which served as a structural concrete for the construction of a supporting column. Two level of milling process was used to recycle...

Construction and demolition waste recycling for production of new concrete is usually limited to the use of coarse aggregates, and efficient utilization of fine subsieve fractions remains an unresolved issue. In the presented research, Portland cement pastes containing 50% finely ground recycled concrete, blended with lime, fly ash, or blast furnac...

This work presents how to assess a rate of adhesion between bituminous binder and mineral aggregate. Asphalt mixtures composed from grade bitumen 50/70, reference or modified with adhesion promoters based on amines, and aggregate (Brant, Zbraslav, Skuteč – 8-16mm) were made and then photographed. Three adhesion assessment approaches were applied: (...

The article focuses on the impact of waste marble powder on resulting cement composites. We investigate of influence waste marble powder on the hydration process and hence the resulting phase composition. The hydration process was investigated using calorimetry and phase composition of the resulting composite by electron microscopy. The results are...

The uplift of concrete overall macroscopic performance by way of alternative additives is commonly used technique. In case of ultra high performance concrete (UHPC), micro-silica is added to the mixture as a micro-filler to the structure of cement binder. As a result, the cementitious matrix macro-mechanical performance is elevated. This paper is a...

The article deals with the selection of a suitable additives in cement composite material for the production of a masonry block. The blocks contains recycled concrete which replacing 40% cement. The recyclate comes from concrete drainage gutters. Based on previous measurements, two hardening accelerators and one superplasticizer were selected. To d...

Poly(vinyl alcohol) (PVA) is a water-soluble, semi-ionic and biocompatible polymer with excellent chemical and thermal stability. The chemical crosslinking of PVA membrane improve its stability towards humidity and water. In the present work, PVA nanofibrous membranes were fabricated using roller electrospinning techniques. The prepared membranes w...

Stabilization of granular materials is a common practice in transport infrastructure structures. It is used mainly for improving the roadbed or for achieving higher performance of base layers. The traditional approach is to use cement, lime hydrated, hydraulic road binder or standard fly-ash in mixing with soil or granular material (gravel) to get...

A comprehensive study consisting of a microstructure investigation, nanoindentation, and mi-cromechanical modeling was performed to identify phases and assess their impact on macro-scopic properties of cement pastes containing waste marble powder. The proposed model, built on the Mori-Tanaka scheme, was used to estimate the effective Young's modulu...

This article deals with using recycled concrete powder as a partial replacement for cement. In particular, we focus on mechanical properties of cement pastes containing recycled concrete powder. We used three different recycled materials. The first recycled concrete powder was obtained from the PB2 and the SB8 railway sleepers, the second one was f...

This work deals with adhesion enhancement between polymer macro-fibers and cement matrix (CEM I 42.5 R). Two types of fibers were used - polypropylene (PP) and polyethylene terephthalate (PET), both having approx. 0.3 mm in diameter. To achieve the increase between the two materials, fibers were surface roughened by means of an oxygen plasma treatm...

The presented work focuses on plasma modifications of polymer and glass micro-fibers (having 32 and 14 μm in the diameter, respectively) used as randomly distributed and oriented reinforcement of concrete composites. Fiber surfaces were modified by means of the low-pressure coupled cold oxygen plasma in order to attain a strong adhesion with the ce...

The paper deals with the problem of processing of a fine fraction of concrete, which occurs after the recycling of old concrete. In this case the old concrete obtained from the construction layers of the D1 motorway was used for experiments. Old concrete was modified by a high-speed milling on 4 types of recycled concrete powder with different fine...

This paper deals with recycling of concrete. Specifically, it discusses the use of micronized concrete, produced during the processing of old concrete, as a partial cement replacement and filler in the cementbased composites. As part of the experiment a several variations of micronized concrete that differed by origin and fineness. For comparison,...

The reduction of industrial pollution is recently one of main goals over all fields. In civil engineering, re-cycling of structural waste provides wide opportunity contributing this effort. This paper focus on re-use of concrete waste, which after further processing can be used in new constructions as partial supplement to the mixture. To investiga...

Presented work focuses on chemical and physical properties of plasma modified polymeric macro-fibers. Polyethylene terephthalate (PET) and polypropylene (PP) fibers having approx. 300 μm in diameter were modified using cold oxygen plasma in order to achieve their surface changes needed for durable bond and adhesion with cement matrixes. A duration...

This article deals with the usage of recycled concrete, which arises from the demolition of concrete structures. The work is focused on the development of mechanical properties (Young's modulus, compressive and flexural strength) depending amount of plasticizer in the mixture. In the experiment were prepared three sets of samples with different amo...

A modulus of elasticity was determined for eight differently foamed cement paste samples. Samples were loaded in the laboratory by a hydraulic press. The force acting on the sample was read directly from the laboratory press. Digital Image Correlation (DIC) analysis were used to draw deformations. Before loading pressure test was applied a random c...

Recycled concrete powder (RCP) mostly consisting of cement paste could be reused as partial cement replacement. The aim of this paper is to compare hydration and mechanical properties of RCP and two types of silica sand powder (SSP). Comparison of those materials combined with cement can highlight the binder properties of recycled concrete powder....

The aim of this work is to describe bonding properties between surface treated polymer fibers and a cement matrix. In order to increase an interaction between the matrix and fiber surfaces, two fiber types having approx. 0.5 mm in diameter were modified by mean of oxygen plasma treatment. Surface physical changes of treated fibers were examined usi...

This paper is focused mainly on nanoindentation of carbon fibers. Fibers are in form of carbon fiber fabric that is used in larger research that is focused on reinforcing beams made of glued laminated timber. Knowledge of this material on macro and micro level will help to understand its behavior in this specific type of use. Nanoindentation is met...

This paper focuses on the mechanical properties investigation of cement pastes reinforced with surface treated polymer fibers. The cement matrix was composed of Portland cement (CEM I 42.5 R, w/c ratio equal to 0.4). Two polypropylene fiber types (micro- and macro-fibers) were used as randomly distributed and oriented reinforcement in volume amount...

This article focus on “blended cement”. The blended cement was created by using waste marble powder (WMP) as a partial replacement for cement. We investigated the influence of WMP on the developing of the dynamic modulus of elasticity and the dynamic shear modulus in time. Four different cement composites with WMP as a partial replacement for cemen...

This article is focused on the mechanical testing of cement-based samples containing a micronized waste marble powder used as replacement of standard binders. Tested materials consisted of cement CEM I 42.5 R (Radotín, Czech Republic) and three different amounts of the marbles (25, 50 and 70 wt. %). Standard bending and compressive tests of the pri...

This paper deals with using fine recycled concrete powder in cement composites as micro-filler and partial cement replacement. Binder properties of recycled concrete powder are given by exposed non-hydrated cement grains, which can hydrate again and in small amount replace cement or improve some mechanical properties. Concrete powder used in the ex...

The article deals with the shrinkage of a cement composite with various contents of waste micronized limestone powder with a fraction size of 0-63 μm and crushed limestone with a fraction size of 0-2 mm. Waste micronized powder is produced by high-speed grinding of marble sludge. The difference in shrinkage of various mixtures has been described by...

This paper is focused on the shrinkage and microstructure of composite cement based materials with different percentage of fine ground recycled concrete. Recycled concrete is in cement mixture as a partial replacement of the filler, which under certain circumstances also functions as a binder component. For the assessment of the microstructure were...

The paper deals with the influence of level of grinding of the recycled concrete. Level of grinding mostly influence the hydration heat evolution of cement paste. Measurement of hydration heat evolution is one of the ways to detect reactive properties of recycled concrete powder modified by high speed mill device. Basic characteristics that most in...

This article is related to the unique application of fly ash-based stabilizer in the track bed of a railway line. In detail, it is focused on following analysis methods of samples structure and properties. The long-term observation of the stabilizer layer is based on the periodical sampling which is done once per year for the following compression...

This paper deals with the use of waste materials from processing of stone in the construction industry. The tested mixtures consisted of Portland cement CEM I 42.5 R, micronized waste marble powder and crushed waste limestone. The article examines the effect of varying the amount of waste on the mechanical properties of the cement composite. At fir...

This article was focused on the influence of the micronized waste marble powder on mechanical properties of cement pastes. Resulting blended cement was composed of Portland cement CEM I 42.5 R and micronized marble powder with different percentage amounts (0 wt. %, 5 wt. %, 10 wt. % and 15 wt. %). Testing was carried at prismatic samples of dimensi...

In previous work focused on using recycled concrete powder as cement replacement the basic dependency of the mechanical properties on the amount of recycled concrete powder was defined. Influence of the amount of recycled concrete powder on the flexural and compressive strength was shown on 0, 33, 67 and 100 wt. % cement replacement. Based on the p...

This article deals with the usage of recycled concrete, which arises from the demolition of concrete structures. The work is focused on the development of mechanical properties (Young's modulus) depending on the microstructure of composite cement based materials with different percentage of fine ground recycled concrete as a partial substitute of t...

The disposal and further recycling of concrete is being investigated worldwide, because the issue of complete recycling has not yet been fully resolved. A fundamental difficulty faced by researchers is the reuse of the recycled concrete fines which are very small (< 1 mm). Currently, full recycling of such waste fine fractions is highly energy inte...

For production of the samples were used several types of aggregate: the standard sand from Zalezlice, the standard sand from Gaza, waste crushed limestone, waste marble sludge and waste micronized marble powder. The Portland cement CEM I 42.5 R produced in Radotín was used as binder. Testing was carried at prismatic samples of dimension 40 × 40 × 1...

The paper deals with comparison of chosen mechanical properties of cement composites reinforced by carbon microfibers. There are tested three mixtures, which are different in their composition. Each sample was tested by destructive methods to determine their mechanical and physical properties. The main object of experiments was verification of an i...

This article deals with utilization of recycled concrete in form of high-speed milled powder into cement based materials. Recycled concrete powder in that form is used as microfiller and cement replacement. This article contains results of mechanical properties of the cement pastes with different amount of recycled concrete powder. The mechanical p...

The paper presents the use of non-destructive testing to determine the evolution of mechanical properties. For testing, we used the resonance method. The measuring device of company Brüel&Kjær was used. Specifically, evolution of dynamic modulus of elasticity (determined from the longitudinal and transverse vibration) and the shear modulus was dete...