Papers by Tomasz Piotrowski
MATEC Web of Conferences, 2018
The development of sustainable building materials with reduced environmental footprint in both, m... more The development of sustainable building materials with reduced environmental footprint in both, manufacturing and operational phases of the material lifecycle, is attracting increased interest in the construction industry worldwide. A recent innovation, the geopolymer foam concrete, combines the performance benefits and operational energy savings achievable through the use of lightweight foam concrete, with the cradle-togate emissions reductions obtained through the use of a geopolymer binder derived from granulated blast-furnace slag (GBFS). In this study mechanical properties of GBFS-based foam concrete were investigated for samples of different water to solid ratio (0.252, 0.287 and 0.321). According to ASTM C 796-97 both mass of the foaming solution and water in sodium silicate solution was considered as part of the total amount of mixing water. As a solid part, GBFS and solid part of activators (NaOH and sodium silicate) was accounted. A group of specimens (40x40x160 beams and ...
Procedia Engineering, 2015
The problem of designing deep foundations is related to many civil engineering structures as it i... more The problem of designing deep foundations is related to many civil engineering structures as it is becoming more common and frequent to construct buildings on soft soils. Pile foundation is a popular deep foundation type used to transfer superstructure load into subsoil and bearing layers. However, accurate prediction of piles' settlement is particularly difficult concerning complicated consolidation process and pile-soil interaction. The objective of this paper is to model a soil-pile system using FEM implemented in Abaqus software. The numerical results of pile bearing capacity and pile settlement were compared with static load test results of CFA piles carried d with engineering analytical calculations according to Eurocode 7 and Polish Standard Code.
Materials
A combination of multiple nondestructive testing (NDT) methods speeds up the assessment of concre... more A combination of multiple nondestructive testing (NDT) methods speeds up the assessment of concrete and increases the precision. This is why the UIR-Scanner was developed at Warsaw University of Technology. The scanner uses an Impact-Echo (IE) method with a unique arrangement of multiple transducers. This paper presents the development of the IE module using numerical models validated with experimental testing. It was found that rectangular arrangement of four transducers with the impactor in the middle is optimal for quick scanning of area for faults and discontinuities, changing the method from punctual to volumetric. A numerical study of void detectability depending on its position with respect to the IE module is discussed as well. After confirmation of the findings of models using experimental tests, the module was implemented into the scanner.
MATERIAŁY BUDOWLANE, 2017
The cement hydration is one of the most complex pro cesses creating the cement matrix. The degree... more The cement hydration is one of the most complex pro cesses creating the cement matrix. The degree of hy dration is a quantity of Portland clinker with gypsum, that as a whole re act with water. For purposes of this analysis it wa s found to be directly proportional to the bound water in the cement paste specimens. Using the gravimetric method the bound water content was determined in samples by calculating the quantitati ve loss of the dry specimens weight after igniting to 1000°C and keeping the temperature for 5h. Obtained results were colla ted with theoretical stoichiometric analysis based on the Bogue and Taylor equations and XRD testing for Portland cement, CEM I 42.5. Obtained outcome has confirmed the relationsh ip between the degree of hydration and the bound water content in cement paste. The influence of the w/c ratio and ce ment oxide components on bound water quantity were also notice d.
Micro and Nanostructured Composite Materials for Neutron Shielding Applications, 2020
Abstract This chapter presents achievements since 1960s relating to improvement in neutron radiat... more Abstract This chapter presents achievements since 1960s relating to improvement in neutron radiation shielding concrete that is a result of material modification, explicit by the addition of neutron attenuating and absorbing components. It has been proven that, contrary to gamma rays, concrete density has a marginal effect on neutron shielding efficiency. Due to the two-stage character of this process (attenuation and absorption) a detailed theory background is given. Finally, the effectiveness of material modification by the change in aggregate (ordinary, heavyweight, iron based, rich in hydrogen) and cement type (Portland, Portland-composite, blast furnace cement) as well as addition of special components (rich in hydrogen, boron, gadolinium) is discussed. Finally, many aspects of neutron shielding should be taken into account when designing an efficient barrier, so depending on the neutron radiation characteristic the individual material design for concrete should be applied.
Construction and Building Materials, 2020
h i g h l i g h t s Bound water content in concrete varies depending on cement and aggregate type... more h i g h l i g h t s Bound water content in concrete varies depending on cement and aggregate type. Bound water content in concrete is independent from w/c ratio. No relation between hydrogen input from bound water and neutron shielding was found. Neutron shielding efficiency can be modified by cement and aggregate change.
Przegląd Spawalnictwa - Welding Technology Review, 2015
Zastosowanie metody ultradźwiękowej do oceny właściwości mechanicznych betonów osłonowych Applica... more Zastosowanie metody ultradźwiękowej do oceny właściwości mechanicznych betonów osłonowych Application of ultrasonic method for assessment of shielding concrete mechanical properties Prof. dr hab. inż. Leonard Runkiewicz-Instytut Techniki Budowlanej; dr inż. Tomasz Piotrowski; mgr inż. Kamil Załęgowski; dr hab. inż. Andrzej Garbacz, prof. PW-Politechnika Warszawska.
MATERIAŁY BUDOWLANE, 2015
Advanced Materials Research, 2015
Concrete has been used as a shield against high-energy photons (gamma) and neutrons since the beg... more Concrete has been used as a shield against high-energy photons (gamma) and neutrons since the beginning of use of nuclear reaction in energy, medicine and research. State of knowledge in shielding concrete technology is that while in case of protection against gamma radiation an increase in density caused by change of aggregate type for heavy-weight one is usually an efficient solution, the protection against neutrons is more complex. It is due to the differences in interactions of neutrons with the matter, depending on their kinetic energy and cross-sections for different reactions of the component atoms of the cement paste and the aggregate. The paper presents the results of the project NGS-Concrete - New-Generation Shielding Concrete. The aim is to design the composition of concrete against ionizing radiation, achieved by the use of experiment based on multi-criteria optimization of materials supported by the Monte Carlo simulations. Better concrete is the one that absorbs more t...
4th International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR-4), 5-7 October 2015, Leipzig, Germany, 2015
Procedia Engineering, 2015
The problem of designing deep foundations is related to many civil engineering structures as it i... more The problem of designing deep foundations is related to many civil engineering structures as it is becoming more common and frequent to construct buildings on soft soils. Pile foundation is a popular deep foundation type used to transfer superstructure load into subsoil and bearing layers. However, accurate prediction of piles' settlement is particularly difficult concerning complicated consolidation process and pile-soil interaction. The objective of this paper is to model a soil-pile system using FEM implemented in Abaqus software. The numerical results of pile bearing capacity and pile settlement were compared with static load test results of CFA piles carried d with engineering analytical calculations according to Eurocode 7 and Polish Standard Code.
Laut EN 1504-10 und ACI Concrete Repair Manual sind Haftfestigkeit und Qualitaet der Grenzflaeche... more Laut EN 1504-10 und ACI Concrete Repair Manual sind Haftfestigkeit und Qualitaet der Grenzflaeche die wichtigsten Merkmale fuer die Beurteilung von Instandsetzungssystemen. Der "Pull-Off-Test" wird am haeufigsten fuer die Bewertung der Haftzugfestigkeit verwendet. Daneben besteht aber auch ein wachsendes Interesse an den zerstoerungsfreien Techniken (ZfP). Das Impact-Echo Verfahren (IE) wird als das vielversprechendste fuer diesen Zweck angesehen. Ziel des Beitrags ist es, den Einfluss der Verbundqualitaet auf die Ausbreitung von Stosswellen bei Anwendung der IE zu analysieren. Die dazu verwendeten Probekoerper wurden so vorbereitet und beschichtet, dass unterschiedlich gute Qualitaeten des Haftverbundes entstanden. Vor der Instandsetzung wurde die Qualitaet des Betonuntergrunds mit Hilfe unterschiedlicher Techniken charakterisiert hinsichtlich Druckfestigkeit, Kohaesion der Oberflaeche, Oberflaechenrauheit und Quantitaet des Rissbildes. Dann wurde ein polymermodifizierter Instandsetzungsmoertel aufgebracht. Nach dem Aushaerten wurden IE-Signale aufgenommen und die Pull-Off-Haftfestigkeit bestimmt. Der Zusammenhang zwischen den charakterisierenden Parametern der Oberflaechenqualitaet, der Haftfestigkeit, des IE-Frequenzspektrums und der Ergebnisse der Wavelet-Analyse des IE-Signals wurde untersucht. (A) ABSTRACT IN ENGLISH: According to EN 1504-10 and ACI Concrete Repair Manual, bond strength and interface quality are the main features of repair systems which need to be assessed. A pull-off test is most commonly used for bond strength evaluation but growing interest in nondestructive techniques (NDT) is recently noted. Impact-echo (IE) is treated as the most promising one for this purpose. The aim of this paper is to analyze an effect of bond quality on stress wave propagation in repair systems. A group of samples has been prepared in order to obtain repair systems of different bond quality. Prior to repair, quality of concrete substrates has been characterized using different techniques: compressive strength, superficial cohesion, surface roughness index and cracking quantification. Then a polymer-modified repair mortar has been applied. After hardening, IE signals have been recorded and pull-off bond strength determined. The relationships between parameters characterizing surface quality, bond strength, IE frequency spectrum and results of wavelet analysis of IE signal have been analyzed. (A)
Procedia Engineering, 2015
Monte Carlo computer simulations confirmed that an increase in density has a minor effect on the ... more Monte Carlo computer simulations confirmed that an increase in density has a minor effect on the weakening of neutron transport and, therefore, the optimum composition of a shielding concrete against gamma radiation is different than the one against neutron radiation. Neutron radiation shielding is a two-step process: slowing down of fast neutrons and absorption of thermal ones. Both result from the atomic composition of the barrier but their dependence on specified atomic compositions and moisture content is different. The aim of the presented research is to develop a high density concrete the composition of which would also assure good efficiency of neutron shielding. Neutron transport through standard cement mortar, PCC mortar, normal-weight concrete and magnetite heavyweight concrete has been analyzed in the paper. The goal in research was to find an influence of the cement type, polymer addition, density and moisture content on the shielding properties against neutron. The research based on convergent results of MC computer simulations and real experiments confirmed the influence of the cement type on fast neutron attenuation. It was also found that each 1% of moisture content makes 10% increase of fast neutron thermalization effectiveness, what is a little less than it was estimated for cement based mortars. It was also proved that heavyweight concrete is not proper solution for shielding against fast neutrons, but its efficiency is visible in the case of thermal neutrons absorption, probably due to increase of Fe content at the expense of Si and O in the atomic composition as well as water retained by magnetite aggregate.
2nd International RILEM Symposium on Advances in Concrete through Science and Engineering, 2006
Impact echo method is treated as one of the most promising methods for a quality control of repai... more Impact echo method is treated as one of the most promising methods for a quality control of repair efficiency. In this method, an analysis of frequency spectrum based on the fast Fourier transform-is used to detect various types of disbonds. Recently, a new tool for signal analysis-wavelet transform-is being implemented in NDT assessment, also in the case of concrete structures. It is a multiresolution timescale methods. The aim of this paper is to analyze the effect of a bond quality on stress wave propagation in repair systems characterized by Fourier and wavelet transforms of impact-echo signal. Three types of concretes and four types of surface preparation have been combined in order to obtain twelve different repair systems. In each case, a polymer modified cement mortar has been applied as a repair material. A quality of concrete substrates has been characterized according different destructive and non destructive techniques: impact-echo, compressive strength, superficial cohesion (pull-off test), surface roughness measurement (sand patch test) and cracking quantification (microscopical observation). The bond quality has been characterized with impact-echo measurement and pull-off test. For each repair system the wavelet analysis of impact-echo signals was performed. The relationships between parameters describing surface quality (roughness, cracking), adhesion strength and stress wave propagation have been analysed.
Research projects performed at the University of Liege and the Warsaw University of Technology ha... more Research projects performed at the University of Liege and the Warsaw University of Technology have pointed out the importance of taking care about surfology of materials: if durability also means sustainability, we may then consider that optimization in material selection is essential for repair efficient. Surfology contributes to understand what will make the contact effective or not, and allow interactions of variable intensities between the materials. Different scales of observation-micro to macro-are needed to exactly represent what happens when materials are put into contact.
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Papers by Tomasz Piotrowski