Wyniki wyszukiwania dla: CONCR
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SIGNIFICANT GUIDELINE FOR THE DAMAGE INDICES APPLIED TO REINFORCED CONCRETE STRUCTURES
PublikacjaIn this paper, based on a deep overview and literature study, the different formulas proposed for damage indices (DIs) applied to reinforced concrete structures under monotonic or cyclic loading are classified and presented. The DIs are applied to quantify the damages to structures, ranging from zero to one. Normally, they are applied to make a decision for repairing or demolition of the structures in the post-earthquake phases. Keywords:...
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Estimation of the parameters of the discrete model of a steel–concrete composite beam
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Influence of grout proportions on modulus of elascity of two-stage concrete
PublikacjaOmówiono badania doświadczalne przeprowadzone dla betonu dwuetapowego. Beton wykonano z kruszywa otoczakowego przy zastosowaniu trzech różnych proporcji w/c i c/p. Na drodze statystycznej opracowano prosty wzór umożliwiający wstępne szacowanie wartości siecznego modułu Younga. Ponieważ metoda dwuetapowa pozwala na zachowanie kontaktu pomiędzy poszczególnymi elementami kamiennego szkieletu wypełniającego formę, wytrzymałość uzyskanego...
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Stress strain relations and modulus of elascity of two stage concrete.
PublikacjaOmówiono badania doświadczalne przeprowadzone dla betonu dwuetapowego. Beton wykonano z trzech różnych kruszyw przy zastosowaniu trzech różnych proporcji w/c i c/p. Wyznaczono związki pomiędzy naprężeniami i odkształceniami. Na drodze statystycznej opracowano wzory umożliwiające wstępne szacowanie wartości siecznego modułu Younga. Ponieważ metoda dwuetapowa pozwala na zachowanie kontaktu pomiędzy poszczególnymi elementami kamiennego...
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An efficient and robust method for predicting asphalt concrete dynamic modulus
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Concrete versus green corridors in road planning. Gdansk case
PublikacjaThe aim of an article is to present the threats which may be caused by the construction of the transit road inside the city structure, and some mitigation measures aiming to eliminate or minimize environmental and landscape damages and social problems. Theoretical guidelines and conclusions will be followed by the example illustrating the problem. As an answer, some guidelines enabling sustainable road planning will be presented....
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Monitoring of concrete curing in extradosed bridge supported by numerical simulation
PublikacjaThe paper describes a mathematical model of concrete curing taking into account kinetics of setting reactions. The numerical model is implemented in the author’s program that was used to monitor thermal effects recorded in the concrete bottom plate of the extradosed bridge. Numerical approach was verified by experimental measurements and used for assessment of the current compressive strength due to degree of hydration of fresh...
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Corrosion behavior of concrete produced with diatomite and zeolite exposed to chlorides
PublikacjaChloride induced reinforcement corrosion is widely accepted to be the most frequent mechanism causing premature degradation of reinforced concrete structures. The electrochemical impedance of reinforcing steel in diatomite- and zeolite-containing concrete exposed to sodium chloride was assessed. Chemical, physical and mineralogical properties of three concrete samples (20% diatomite, 20% zeolite, and a reference containing neither)...
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Damage of a post-tensioned concrete bridge – Unwanted cracks of the girders
PublikacjaThe cracking of a post-tensioned T-beam superstructure, which was built using the incremental launching method, is analyzed in the paper. The problem is studied in detail, as specific damage was observed in the form of longitudinal cracks, especially in the mid-height zone of the girder at the interface of two assembly sections. The paper is a case study. A detailed inspection is done and non-destructive testing results of the...
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Static and dynamic concrete calculations: Breakable aggregates in DEM model
PublikacjaThe paper deals with the calculations of a 3-point bending beam under static and dynamic loads. The real microstructure was obtained from laboratory tests using micro-tomography images. The quasi-static results were compared directly with experimental data at both macro and micro levels. Subsequently, higher strain rates were applied to investigate dynamic effects. The study focused on the influence of dynamic loading on the macroscopic...
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Machine learning-based prediction of preplaced aggregate concrete characteristics
PublikacjaPreplaced-Aggregate Concrete (PAC) is a type of preplaced concrete where coarse aggregate is placed in the mold and a Portland cement-sand grout with admixtures is injected to fill the voids. Due to the complex nature of PAC, many studies were conducted to determine the effects of admixtures and the compressive and tensile strengths of PAC. Considering that a prediction tool is needed to estimate the compressive and tensile strengths...
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Machine learning-based prediction of preplaced aggregate concrete characteristics
PublikacjaPreplaced-Aggregate Concrete (PAC) is a type of preplaced concrete where coarse aggregate is placed in the mold and a Portland cement-sand grout with admixtures is injected to fill the voids. Due to the complex nature of PAC, many studies were conducted to determine the effects of admixtures and the compressive and tensile strengths of PAC. Considering that a prediction tool is needed to estimate the compressive and tensile...
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Experimental study on ultrasonic monitoring of splitting failure in reinforced concrete
PublikacjaThis paper investigates inspection of reinforced concrete elements sensitive to the splitting failure. The behaviour of a reinforced concrete specimen subjected to a tensile stress is considered. The damage detection procedure is based on the ultrasonic wave propagation technique. The piezoelectric transducers are located on both ends of the specimen and the measurements are taken periodically during the incrementally increased...
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The Application of Fibres from Recycled Postconsumer Tyres for Concrete Reinforcement
PublikacjaPoland as a Member State is obliged to implement the EU specific environmental legislation focused on the reduction, transport and treatment of waste. The Landfill Directive prohibited the landfilling of whole tyres and their by-products. Although the EU Directive of Waste limits the use of tyres as secondary fuel, Poland is still the EU leader in burning tyres in cement kilns. Post-consumer tyres are utilised in a number of...
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Ultrasonic diagnostics of concrete T-beams used in bridge structures
PublikacjaThis paper describes a method of ultrasonic diagnostics used for prefabricated concrete elements. The studies are focused on the applicability of nondestructive techniques based on impulse and wave packet induced elastic waves for the condition assessment of T-shaped bridge beams. Experimental tests were performed for the prestressed beam used for the superstructure of the viaduct on A1 highway near Toruń. In addition numerical...
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Computational modelling of concrete behaviour under static and dynamic conditions
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Fibres from recycled post-consumer tyres for concrete reinforcement
PublikacjaW pracy przedstawiono aktualną sytuację dot. wykorzystania drutu stalowego z recyklingu opon samochodowych. Przedstawiono wyniki badań przeprowadzonych w laboratorium Katedry Konstrukcji Betonowych i Technologii Betonu nad zastosowaniem włókien stalowych z recyklingu do zbrojenia betonu. Otrzymane wyniki porównano z próbkami fibrobetonu uzyskanego na bazie przemysłowo produkowanych włókien stalowych.
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Durability of Asphalt Concrete Subjected to Deteriorating Effects of Water and Frost
PublikacjaThe paper presents testing of the detrimental effects of water and frost on asphalt pavements. It included laboratory testing of 5 fatigue life of asphalt concrete that was subjected to action of water and frost and field testing of damages caused by water and frost on 6 existing asphalt pavements, such as stripping, raveling, and potholes. Laboratory simulation of water and frost action was based on the 7 original AASHTO T283...
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Application of guided waves in the evaluation of steel-concrete adhesive connection
PublikacjaThe aim of the paper is the application of guided waves in the evaluation of a condition state of adhesive connection between steel and concrete. The study concerns a push-out specimen consisting of two steel plates glued to opposite faces of a concrete cube with the use of structural adhesive. Wave propagation in the specimen without external load is investigated both experimentally and numerically. The second stage of the investigation...
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Analysis of Transparent Concrete as an Innovative Material Used in Civil Engineering
PublikacjaSince the dawn of history concrete has been, right behind stone and brick, one of the oldest building materials. The ancient Romans took advantage of its opportunities. They constructed amazing architectural objects, which survived centuries as whole buildings or parts of them. Concrete is so ubiquitous, that when we are walking in a newer districts of cities we are virtually surrounded by concrete from everywhere. Sometimes...
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Static load test on concrete pile – instrumentation and results interpretation
PublikacjaFor some time (since 8-10 years in Poland) a special static load tests on instrumented piles are carried out. Such studies are usually of a scientific nature and provide detailed quantitative data on the load transfer into the ground and characteristics of particular soil layers interaction with a pile shaft and pile base. Deep knowledge about the pile-subsoil interaction can be applied for a various design purposes, e.g. numerical...
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Simulations of fracture in concrete elements using continuous and discontinuous models
PublikacjaArtykuł przedstawia wyniki symulacji MES w elementach betonowych przy zastosowaniu modeli ciągłych i nieciągłych. Stosując modele ciągłe symulowano proces lokalizacji odkształceń. Stosując modele nieciągłe symulowano proces zarysowania. Obliczenia wykonano dla różnych typów obciążeń.
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Experimental and numerical investigations for GPR evaluation of reinforced concrete footbridge
PublikacjaThe GPR method has increasingly found application in non-destructive testing of reinforced concrete structures. This paper presents the new approach of modelling of the electromagnetic wave propagation for reinforced concrete structures with a complex system of the reinforcement. Simulations of the GPR field were performed on a three-dimensional model of a footbridge using the FDTD method. Numerical maps were compared with results...
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Mechanical properties of two-stage concrete modified by silica fume
PublikacjaAbstract. Two-stage concretes, despite the fact that they have proven themselves in various types of construction, have not been studied to the same extent as traditional heavy concretes. Therefore, the article developed the composition of frame concrete with various additives in the composition of the cement-sand mortar. A comparison of the mechanical characteristics of the developed compositions with the addition of silica fume...
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Causes of damage and methods of repairing floor made on polystyrene concrete
PublikacjaThe paper describes damages, tests and repair of the floor made on existing ceiling and expanded polystyrene concrete underlay. The floor was built on a reinforced concrete ceiling with an area of about 1050 m2. Significant damage in the form of cracks, detachments and unevenness was found in the floor. In order to determine the causes of damage, in situ tests and laboratory tests were carried out. It was found that the damage...
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Numerical Study of Concrete Mesostructure Effect on Lamb Wave Propagation
PublikacjaThe article presents the results of the numerical investigation of Lamb wave propagation in concrete plates while taking into account the complex concrete mesostructure. Several concrete models with randomly distributed aggregates were generated with the use of the Monte Carlo method. The influence of aggregate ratio and particle size on dispersion curves representing Lamb wave modes was analyzed. The results obtained for heterogeneous...
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Concrete-filled FRP tubular members in marine and bridge structures
PublikacjaConcrete core of the concrete-filled tubes (CFTs) with circular cross-section is in the case of an axial compression subjected to a spatial state of compressive stresses. This state leads to enhancement in the concrete strength. The enhancement is utilized in Eurocode 4 design procedures for CFSTs (i.e. CFTs with tube made of steel). The structural design of CFFTs (i.e. CFTs with tube made of Fibre Reinforced Polymer - FRP) is...
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Experimental Study of the Resistance to Influence of Aggressive Liquids on Lightweight Concrete
PublikacjaIn light of the scientific research, the corrosion of concrete structures is one of the main problems that may reduce their durability due to the negative impact of the natural environment. The paper analyzes the influence of the type of component on the selected properties of lightweight concrete subjected to the influence of aggressive liquids. Four concrete mixes were prepared with a granular aggregate made of foamed glass (GEGA)...
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Study of the Resistance to Influence of Aggressive Liquids on Concrete with Lightweight Aggregate
PublikacjaThe corrosion of the structure of concrete caused by the aggressive external environment is one of the main problems that can reduce the durability of buildings. The paper analyzes the influence of the type of component on selected properties of lightweight concrete (LWC) exposed to aggressive liquids. When lightweight concrete containing porous aggregates is used, the influence of an aggressive environment may be of particular...
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Deterioration and Protection of Concrete Elements Embedded in Contaminated Soil: A Review
PublikacjaCoating materials are considered one of the most antique materials of human civilization; they have been used for decoration and the protection of surfaces for millennia. Concrete structures—due to their permanent exposure to different types of environments and contaminants—require the use of coatings that contribute to its preservation by reducing the corrosion of its components (steel and aggregates). This article intends to...
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Maturity curve for estimating the in-place strength of high performance concrete
PublikacjaThe paper presents the maturity curve for estimating the in-place early-age compressive strength of concrete. The development of appropriate maturity curve is a complex process. It is important to correctly determine the datum temperature and activation energy, which can be obtained in mortar tests. This paper describes an investigation of the accuracy of the maturity method to estimate the strength when different way to rate constant...
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Modelling of fracture process in concrete using a novel lattice model.
PublikacjaArtykuł omawia wyniki modelowania procesu zarysowania w elementach betonowych przy zastosowaniu dyskretnego modelu kratownicowego. Beton był modelowany na poziomie mezoskali z uwzględnieniem 3 faz: kruszywa, zaczynu cementowego i stref kontaktu. Obliczenia wykonano dla rozciągania i ścinania połączonego z rozciąganiem.
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A 3D lattice model to describe fracture process in fibrous concrete
PublikacjaArtykuł omawia wyniki modelowania procesu zarysowania w elementach betonowych zawierające stalowe włókna przy zastosowaniu dyskretnego modelu kratownicowego. Beton był modelowany na poziomie mezoskali z uwzględnieniem 5 faz: kruszywa, zaczynu cementowego, włókien i obu stref kontaktu. Obliczenia trójwymiarowe wykonano dla jednoosiowego rozciągania.
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Computational modelling of concrete behavior under static and dynamic conditions
PublikacjaW artykule zaproponowano wyniki obliczeń MES dla betonu podczas dynamicznego obciążenia. Przyjęto model sprężysto-plastyczno-lepki z nielokalnym osłabieniem. Obliczenia MES dla elementów betonowych pod obciążeniem dynamicznym o różnej prędkości obciążenia porównano bezpośrednio z doświadczeniami.
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FE analysis of reinforced concrete corbels with enhanced continuum models
PublikacjaW artykule pokazano wyniki MES symulacji wsporników żelbetowych. Zachowanie wsporników modelowano przy zastosowaniu 3 różnych modeli betonu: sprężysto-plastycznego, degradacji sprężystej i rozmytych rys. Modele rozszerzono o długość mikrostruktury przy zastosowaniu teorii nielokalnej. Wyniki numeryczne porównano z doświadczeniami z literatury.
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Determination of representative volume element in concrete under tensile deformation
PublikacjaW artykule podano sposoby określenia elementu reprezentatywnej objętości w betonie podczas rozciągania. Obliczenia wykonano przy zastosowaniu izotropowego modelu degradacji sztywności rozszerzonego o długość charakterystyczną mikrostruktury w ramach teorii nielokalnej. Zaproponowano 2 różne metody wyznaczania elementu reprezentatywnej objętości niezależnego od warunków brzegowych.
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DEM ANALYSIS OF EFFECT OF INTERFACIAL TRANSITIONAL ZONES ON FRACTURE IN CONCRETE.
PublikacjaArtykuł omawia wyniki numeryczne dotyczące pękania betonu uzyskane stosując metodę elementów dyskretnych. Trójwymiarowe obliczenia wykonano dla próbek betonowych podczas zginania. Beton został opisany jako model 4-fazowy. Mikrostrukturę betonu przyjęto na podstawie 3D zdjęć mikro-tomograficznych. Zbadano wpływ stref przejściowych na wytrzymałość i proces pękania. Wyniki numeryczne zostały porównane z wynikami doświadczalnymi. Uzyskano...
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Mesoscopic simulations of crack propagation in concrete using cohesive elements
PublikacjaThe paper presents results of two-and three-dimensional meso-scale simulations of fracture in notched concrete beams subjected to three-point bending test. Concrete was assumed as a 3-phase material composed of aggregate grains placed in the cement matrix with Interfacial Transitional Zones (ITZs) between then. In 2D simulations macro-voids were also taken into account. The particle distribution was taken from real concrete beams...
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Numerical investigations on early indicators of fracture in concrete at meso-scale.
PublikacjaFracture is a major reason of the global failure of concretes. The understanding of fracture is important to ensure the safety of structures and to optimize the material behaviour. In particular an early prediction possibility of fracture in concretes is of major importance. In this paper, concrete fracture under bending was numerically analysed using the Discrete Element Method (DEM). The real mesoscopic structure of a concrete...
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Study of fracture process in concrete using a discrete lattice model.
PublikacjaW artykule omówiono wyniki numeryczne z zastosowaniem dyskretnego modelu rusztowego złożonego z belek do symulacji procesu zarysowania w elementach betonowych. Obliczenia wykonano dla różnych procesów obciążeniowych. Wyniki porównano jakościowo z wynikami doświadczeń.
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Modelling of concrete behaviour with a non-local continuum damage approach
PublikacjaW artykule przedstawiono wyniki numerycznej dla różnych problemów brzegowych związanych z powstawaniem rys w betonie. Obliczenia wykonano przy zastosowaniu modelu zniszczeniowego (z uwzględnieniem degradacji sztywności). Do opisu rys, model rozszerzono o nielokalność.
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Open porosity and oven-dry density of concretes containing magnetite aggregate (M0-M100) mixes
Dane BadawczeRaw data for determination of open porosity and oven-dry densities of concretes containing different amount of magnetite aggregate (M0-M100) mixes. Sample designation is related to the publication associated with dataset.
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MAGAZINE OF CONCRETE RESEARCH
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Development of 3D printed heavyweight concrete (3DPHWC) containing magnetite aggregate
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Impact of Surfactant and Calcium Sulfate Type on Air-Entraining Effectiveness in Concrete
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Experimental Verification of Natural Vibration Models of Steel-concrete Composite Beams
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Vibration of Steel–Concrete Composite Beams Using the Timoshenko Beam Model
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Preliminary Studies on a Lightweight Porous Cement-Based Composite – Gel Concrete
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Experimental and Numerical Investigations of the Effect of Curing Conditions on the Temperature Rise of Concrete
PublikacjaThis paper presents experimental and numerical studies investigating the impact of three curing conditions on temperature evolution in concrete cubes. The tests were performed on samples of the same volume (3.375 dm3) under different curing conditions: room temperature, insulation boxes, and adiabatic calorimeter. Various cements (Portland cement, Portland composite cement, and blast furnace slag cement) and aggregates (gravel...
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Influence of the Addition of Recycled Aggregates and Polymer Fibers on the Properties of Pervious Concrete
PublikacjaThe aim of the study was to check the possibility of reusing aggregate from recycled concrete waste and rubber granules from car tires as partial substitution of natural aggregate. The main objective was to investigate the effects of recycled waste aggregate modified with polymer fibers on the compressive and flexural strength, modulus of elasticity and permeability of pervious concrete. Fibers with a multifilament structure and...