Dariusz. Gawin

• Professor
• Professor (Full) at Lodz University of Technology

The application of recycled concrete aggregates (RCAs) has become increasingly popular for different types of structures, as presented in several studies. However, depending on the type of structure and the region, RCAs might have different properties. This study aims to investigate the application of RCAs of different origins for substructure laye...

Building energy and environmental efficiency is presently one of the most important research subjects due to global climate change and the actual geopolitical situation. Residential buildings should provide a comfortable environment for the occupants while they spend up to 90% of their life indoors. Moreover, a comfortable indoor environment should...

The protection of the natural environment and countering global warming are crucial worldwide issues. The residential sector has a significant impact on overall energy consumption and associated greenhouse gas emissions. Therefore, it is extremely important to focus on all of the activities that can result in more energy efficient and sustainable c...

The development of energy-efficient buildings and sustainable energy supply systems is an obligatory undertaking towards a more sustainable future. To protect the natural environment, the modernization of urban infrastructure is indisputably important, possible to achieve considering numerous buildings as a group, i.e., Building Energy Cluster (BEC...

An EPS ventilated panel, which may be applied as an external insulation to humid walls, is investigated. Dimensions of the air channel sections have been determined using the Ansys software. Afterwards, the drying rate of the walls externally insulated with EPS, mineral wool and EPS ventilated panel has been compared using the WUFI software. The ve...

Nowadays, natural environment protection and sustainable development became common and necessary issues for all the economic sectors. It is extremely important to focus on all the efforts resulting in the most efficient and sustainable power sources and electric power grid. Typically, the residential districts are connected by electric grids, which...

In the calculations of buildings’ thermal comfort, the input parameters are usually considered as strictly determined values. Numerous of them may be characterized by certain probability density functions. In the energy related problems, the uncertainty analyses are usually performed using the Monte Carlo method. However, this method requires multi...

In the analyses of the uncertainty propagation of buildings’ energy-demand, the Monte Carlo method is commonly used. In this study we present two alternative approaches: the stochastic perturbation method and the transformed random variable method. The energy-demand analysis is performed for the representative single-family house in Poland. The inv...

In the decision-making process during the office buildings’ design or management, a significant problem arises from the necessity of simultaneous satisfaction of the users’ thermal comfort and minimization of the energy demand. Since the features of the materials, the comfort perception and the number of people are uncertain quantities, the energy...

The paper presents a novel mathematical model of coupled hygro-thermo-mechanical processes in a porous material, partially saturated with liquid water and exposed to temperatures below the freezing point of pore water. Water – ice phase change is modelled by means of a non-equilibrium approach considering both water supercooling and a hysteresis of...

Hygric properties of porous building materials are important for hygrothermal analysis. Their experimental determination is however not always reliable, shown by the discrepant results from different laboratories on the same materials. In this study, a recent round robin campaign initiated by KU Leuven (Belgium) and participated in by eight institu...

Worldwide policy referring to global warming and air pollution assumes several main guidelines, in which Renewable Energy Sources (RES) usage simultaneously with limitation of fossil fuels in energy production seems to be a major goal. Nowadays, the continuous growth of RES usage within final energy consumption is becoming an obvious part of many c...

In this article a simple computer tool that can predict energy demand of residential buildings area in Poland by means of artificial neural network is developed and its application is demonstrated. Authors focused on energy demand analyses for single-family houses, representative for the Polish household sector. Advanced computer simulations were p...

The reliable determination of the hygric properties of porous building materials is important. In earlier round robin campaigns large discrepancies of measured hygric properties were found among different labs. Later studies indicated that differences in lab conditions and more importantly, personnel’s operation procedures and data processing metho...

This article presents a novel mathematical model of hygro-thermal processes in a porous material, partially saturated with liquid water, exposed to temperatures below the freezing point of pore water. Water–ice phase transition is modeled by means of a kinetic approach considering water supercooling and thermodynamic non-equilibrium of the phases,...

This article presents an analysis of energy demand for an office buildings complex located in Gdansk, Poland. The analyses were performed with advanced computer simulations using the Energy Plus software. Simulations were validated by comparing their results with the actual energy consumption data for one of the buildings belonging to the complex a...

Thermal spalling is a deterioration phenomenon which is of fundamental importance during durability analysis of concrete structures exposed to high temperature, e.g. during a fire. To assess the risk of this damage mechanism for a real concrete structure, numerical simulations are usually applied since experimental tests are very costly. Some aspec...

The main subject of this paper is the investigation of the influence of the alkali-silica reaction on the microstructure and the transport properties of the cement-based materials. In the experimental research, mortar bars prepared with two different aggregates and stored in conditions of various alkali content were examined. Influence of the react...

A model of the alkali-silica reaction, which takes into account couplings between thermal, hygral, mechanical and chemical phenomena in concrete, has been discussed. The ASR may be considered at macroscopic or mesoscopic scale. The main features of each approach have been summarized and development of the model for both scales has been briefly desc...

In this work, a coupling strategy for the analysis of a tunnel under fire is presented. This strategy consists in a “one-way” coupling between a tool considering the computational fluid dynamics and radiation with a model treating concrete as a multiphase porous material exposed to high temperature. This global approach allows for taking into accou...

The article presents an analysis for the Polish Baltic seaside concerning wind farm potential for producing electricity for housing. The analysis includes comparison of onshore and offshore wind climate parameters important for electrical energy production. The wind turbine parameters were assumed from the datasheet for two chosen turbines while th...

Experimental research, in which mortars prepared with reactive aggregates have been exposed to different conditions, has been performed. The samples have been stored in water or 1 M NaOH water solution at 80 °C. Based on the observed strains, ASR extent has been calculated. Mathematical model of combined action of hygro-thermal, chemical and mechan...

Poszukując optymalnego sposobu eksploatacji budynku, występują trudności w znalezieniu rozwiązania charakteryzującego się jak najmniejszym zużyciem energii, przy jednoczesnym zapewnieniu komfortu cieplnego ludziom w nim przebywającym, ponieważ kryteria te są sobie przeciwstawne. Sprowadza się to do rozwiązania problemu optymalizacji wielokryterialn...

One of the most adverse phenomena which is related to salt and moisture presence in the pore system of building materials is salt crystallization. The microstructure analysis (using mercury intrusion porosimetry) of cement mortar samples due to cyclic salt crystallization is analyzed. We assume that salt crystals grow only from the supersaturated s...

In the following paper a combined approach for the analysis of concrete structure under fire is presented. The coupled tool combines computational fluid dynamics (CFD) with structural analysis (FEM). At this first stage the coupling is performed with a one way strategy transferring the results from CFD to FEM. The thermal load on the structure and...

W artykule przedstawiono analizę wyników symulacji energetycznych dotyczących grupy obiektów użyteczności publicznej o zróżnicowanej funkcji połączonych w lokalny obszar bilansowania w celu redukcji szczytowej mocy elektrycznej w okresie letnim. Przeanalizowano zapotrzebowanie na moc chłodniczą obiektów tego obszaru w okresie doby w polskich warunk...

The paper considers water solidification in porous materials. Mathematical model describing heat and water transport in deformable porous materials considering the kinetics of water phase change was proposed. The crystallization pressure was determine using the volume averaged Everett's equation. The ice-induced destruction of concrete was modeled...

Cyclic water freezing/thawing in concrete is a major cause of civil engineering infrastructure deterioration in cold climates. Ice exerts some additional pressure on the skeleton, causing its damage, which is dependent on the material microstructure. The total open porosity, pore size distribution, contribution of ink-bottle pores, capillary suctio...

Delayed Ettringite Formation is a type of chemical degradation of moist concrete exposed at early ages to heating up to temperature of about 70-80°C. The material deterioration is caused by expanding phases produced by the ettringite reaction. A phenomenological, rate-type model of the DEF strains, considering effect of the temperature and duration...

The gas permeability and strength properties of the concrete and cement mortar with three different dosages of polypropylene fibers were tested. The obtained results confirm a significant influence of the fibers on the increase of permeability of cement-based materials heated above 180°C. At the same time, no influence of the polypropylene fibers c...

Overview Assessment of cement-based materials performance under severe conditions in terms of temperature and pressure is of great interest in nuclear engineering applications and in safety evaluation in tall buildings and in tunnels [1–4]. In particular, when concrete structures are exposed to high temperature a rather complex analysis is required...

In this paper we present an efficient tool for simulation of a fire scenario in a tunnel. The strategy adopted is based on a 3D-2D coupling technique between the fluid domain and the solid one. So, the thermally driven CFD part is solved in a three dimensional cavity i.e. the tunnel, and the concrete part is solved on 2D sections normal to the tunn...

A general approach to modeling chemical degradation processes in cementitious materials, due to combined action of variable hygral, thermal, chemical and mechanical loads, is presented. Mechanics of multiphase porous media and damage mechanics are applied for this purpose, and kinetics of chemical processes is described with evolution equations bas...

A general approach to modelling chemical degradation processes in building materials, due to combined action of variable hydrothermal, chemical and mechanical loads, is presented. Mechanics of multiphase porous media and damage mechanics are applied for this purpose, and kinetics of degradation processes is described with evolution equations based...

The paper considers the change of cement mortar microstructures due to sodium sulfate crystallization. The pressure generated during the crystallization, causes the deterioration of the solid skeleton of cement-based materials. The magnitude of stress induced by crystals growing in the pores strongly depends on the geometry of the system. The influ...

A novel mathematical model of chemo-hydro-thermo-mechanical behavior of porous building materials considering salt transport and crystallization is presented in the paper. The additional pressure, which is generated during the salt crystallization, is taken into account by means of the effective stress principle. The solid surface fraction in conta...

The mobility of water in hardening cement paste is an important aspect in view of the effectiveness of internal curing. A mechanistic-type numerical model of cementitious materials is applied for the analysis of water migration kinetics from internal curing agents [superabsorbent polymers (SAP)] into hydrating cement pastes with a low water-to-ceme...

A general approach to modelling chemical degradation processes in cement based materials, due to combined action of hygro-thermal, chemical and mechanical loads, is presented. Mechanics of multiphase porous media and damage mechanics are applied for this purpose. The mass-, energy- and momentum balance equations, and constitutive and physical relat...

Application of mechanics of multi-phase porous media for modeling cement based materials at high temperature is presented. The considerations are based on the mathematical model of mechanistic type, developed by the authors within recent years. The model has been previously experimentally validated and successfully applied for analyzing performance...

A mathematical model of combined action of hygro-thermal, chemical and mechanical loads is proposed to describe chemical degradation of cement based materials due to ASR and cracking due to material stresses. The model is based on mechanics of multiphase reactive porous media and isotropic damage theory. The mass-, energy- and momentum balance equa...

A new numerical model for the simulation of ASR in cement-based materials considering both the effect of temperature and moisture content is presented. A mechanistic approach, based on the mechanics of porous media, was used to obtain the governing equations by means of a hybrid mixture theory. The model equations, mass (water species and dry air),...

Prediction of the influence of internal curing both on the material behavior during maturing and on its final physical properties is an important issue in concrete research. A novel, mechanistic-type numerical model of concrete is applied for modeling the chemo-physical phenomena taking place during internal curing. The model takes into account ful...

In this paper a general model for the analysis of concrete as multiphase porous material, obtained from microscopic scale by applying the so-called Hybrid Mixture Theory, is presented. The final formulation of the governing equations at macro-level is obtained by upscaling their local form from the micro-scale. This procedure allows for taking into...

The paper deals with modelling of hygro-thermal performance and thermo-chemical degradation of concrete exposed to high temperature. Several possible simplifications in modelling of heat and mass transport phenomena in heated concrete are considered and their effect on the results of numerical simulations is analyzed.A mathematical model of concret...

The paper deals with modelling of hygro-thermal performance and thermo-chemical degradation of concrete exposed to high temperature. Several possible simplifications in modelling of heat and mass transport phenomena in heated concrete are considered and their effect on the results of numerical simulations is analyzed.In part I of the companion pape...

We discuss the role of thermodynamic consistency in multiphysics and multiscale models, and how it can be preserved among scales. The quest for consistency and adoption of thermodynamic non equilibrium models has led to remarkable results in the field of fluid-solid interaction problems such as an improved model for drying shrinkage in concrete or...

Water and salts strongly influence the durability of porous materials. One of the most adverse phenomena which is related to the salt and moisture presence in the pore system of building materials is salt crystallization. The process is associated with the supersaturation ratio. The salt phase change kinetics is taken into account during the modeli...

In this paper a general model for the analysis of concrete as multiphase porous material, obtained from microscopic scale by applying the so-called Hybrid Mixture Theory, is presented. The final formulation of the governing equations at macro-level is obtained by upscaling their local form from the micro-scale. This procedure allows for taking into...

n this paper we discuss two multi-scale procedures, both of mathematical nature as opposed to purely numerical ones. Examples are shown for the two cases. Attention is also devoted to thermodynamical aspects such as thermodynamic consistency and non- equilibrium thermodynamics. Advances for the first aspect are obtained by adopting the thermodynami...

Internal curing by means of superabsorbent polymers (SAP) is an efficient method for providing additional curing water in high performance concrete with low w/c. In order to fully use the potential of internal curing reservoirs, the water needs to be supplied possibly uniformly in the whole volume of hydrating cement paste and moreover at rates suf...

This paper presents a unified mathematical approach to model the hydro-thermo-mechanical behavior of saturated and partially saturated porous media by considering the effects of air dissolved in liquid water. The model equations are discretized by means of the Finite Element method. A correspondingly updated code is used to analyze two examples; th...

The paper presents a new mathematical model of hydro-thermo-chemo-mechanical behavior of cementitious materials exposed to contact with the deionized water. For analyzing the calcium leaching process, an equation describing kinetics of the process is used instead of an equilibrium curve commonly used in previous isothermal models. This allows takin...

An extension of a mathematical model for non-isothermal multiphase materials to consider the dissolution of air in liquid water and air mass sources during its desorption at lower water pressure is presented. The solid skeleton is assumed elasto-plastic; heat, water and air flows and water phase changes are taken into account. Physics of air dissol...

The durability of most porous building materials is strongly related with moisture and salt transport mechanisms. Mathematical model describing heat and moisture transport in materials containing salt is presented. The main storage parameter which describes the hygral state of any porous material is the sorption isotherm. The degree of saturation o...

In this work a general model for the analysis of concrete as multiphase porous material, obtained from microscopic scale by applying the so called Hybrid Mixture Theory, is presented. Two specific forms of the general model adapted to the case of concrete at early ages and beyond and to the case of concrete degradation due to the leaching process a...

In this paper a general model for the analysis of concrete as multiphase porous material, based on the so-called Hybrid Mixture Theory, is presented. The development of the model equations, taking into account both bulk phases and interfaces of the multiphase system is described, starting from the microscopic scale. An exploration of the second law...

Part 1 of the paper presents a new mathematical model of hydro-chemo-mechanical behavior of cementitious materials exposed to contact with the deionized water. For analyzing the calcium leaching process, an equation describing kinetics of the process is proposed instead of an equilibrium curve commonly used in previous models. This allows taking di...

The durability of most porous building materials is strongly related with moisture and salt transport mechanisms. They are closely related with inner structure of a material. Therefore, influence of salt on porous structure of cement mortar, initially saturated with different solutions of NaCl, was analysed. SEM and MIP tests were performed and cha...

A novel model of hygro-thermal performance of cement-based building materials during their maturing, considering evolution of their strength properties and deformations (shrinkage and creep strains), described in terms of effective stress is briefly presented. Creep is described by means of the modified microprestress — solidification theory by Baz...

A very characteristic mode of concrete damage at high temperature, especially for the materials characterized by a low intrinsic permeability, is the so called thermal spalling. In this work a mathematical model, which considers concrete as multiphase porous material, is applied to defining some spalling indexes based on various collapse mechanisms...

The paper presents the results of numerical study on the influence of two different internal curing techniques upon the strains and hygro-thermal performance of maturing concrete. The simulations are performed with the recently developed numerical model of concrete by Gawin et al. [1, 2] which is briefly presented here. The effective properties and...

The assumption that pressures of water and gas in concrete at high temperature are equal one to another and its theoretical consequences are discussed. The results of hygro-thermal simulations performed by Tenchev and Purnell are analysed and compared to the Authors’ results based on the assumption about local thermodynamic equilibrium.

A mathematical model of hygro-thermo-mechanical phenomena in heated concrete, treated as multiphase porous material is briefly presented. Some modifications necessary to analyse high–temperature performance of a concrete containing the PP-fibres have been introduced, experimentally validated and applied for analysis of performance of a concrete tun...

A novel model of mechanical performance of concrete at early ages and beyond, and in particular, evolution of its strength properties (aging) and deformations (shrinkage and creep strains), described in terms of effective stress is briefly presented. This model reproduces such phenomena known from experiments like drying creep or some additional st...

Physical phenomena in heated concrete, leading to thermal spalling are discussed. Contribution of the stored elastic energy and vapour pressure build-up to the kinetic energy of spalled concrete pieces is estimated. A mathematical model of hygro-thermo-chemo-mechanical phenomena in heated concrete is presented. Different simplified models of therma...

In Part I of this paper (Int. J. Numer. Meth. Eng., in print) a mechanistic model of hygro-thermo-chemical performance of concrete at early ages has been introduced. Additionally, as compared to the existing models (e.g. J. Eng. Mech. (ASCE) 1995; 121(7):785–794; 1999; 125(9):1018–1027), an effect of relative humidity on cement hydration rate and a...

Part 1 of the paper presents a new numerical model of hygro-thermal and hydration phenomena in concrete at early ages and beyond. This is a solidification-type model where all changes of material properties are expressed as functions of hydration degree, and neither as maturity nor as equivalent hydration period as in maturity-type models. A mechan...

A mathematical and numerical model to predict the non-linear behaviour of concrete as multiphase porous material is proposed. The model can be usefully applied to several practical cases: evaluation of concrete performance in the high temperature range, e.g. during fire, to early stages of maturing of massive concrete structures, to shotcrete in tu...

In this paper, the authors present a mathematical description of a multi-phase model of concrete based on the second law of thermodynamics. Explo-itation of this law allowed researchers to obtain definitions and constitutive relationships for several important physical quantities, like capillary pres-sure, disjoining pressure, effective stress, con...

This work deals with a new mathematical/numerical model for the analysis of the behaviour of concrete considered as multiphase viscous porous material from early ages to long term periods. This is a solidification-type model where all changes of material properties are expressed as functions of hydration degree, and not maturity nor equivalent hydr...

A mathematical model describing coupled heat, moisture and salt transport in porous materials is presented. Salt dissolved in water can be transported due to various mechanisms: dispersion caused by the salt concentration gradient, and advection resulting from the capillary pressure gradient. The influence of salt on the physical properties of wate...

The results of SEM and MIP tests of specimens made of cement mortar, which were initially saturated with water solution of different concentration of the NaCl salt, are discussed. The theoretical research, which were carried out in order to estimate the influence of dissolved and precipitated salt on transport of heat and moisture in porous buildin...

This paper presents an analysis of some experimental results concerning micro-structural tests, permeability measurements and strain-stress tests of four types of High-Performance Concrete, exposed to elevated temperatures (up to 700 degrees C). These experimental results, obtained within the "HITECO" research programme are discussed and interprete...

In the Part 1 paper (Gawin, et al. 2005) some experimental results concerning micro-structural tests, permeability measurements and stress-strain tests of four types of High Performance Concrete, exposed to elevated temperatures (up to 700 degrees C) are presented and discussed. On the basis of these experimental results parameters of the constitut...

A fully coupled model of hygro-thermo-chemo-mechanical phenomena in concrete is presented. A mechanistic approach has been used to obtain the governing equations, by means of the hybrid mixture theory. The final equations are written in terms of the chosen primary and internal variables. The model takes into account coupling between hygral, thermal...

A constitutive model for the analysis of deformations of concrete subject to transient temperature and pressures is proposed. In these severe conditions concrete structures experience spalling phenomenon, which is the violent or non-violent breaking off of layers or pieces of concrete from the surface of a structural element when it is exposed to h...

A mathematical model for analysis of hygro-thermal behaviour of concrete as a multi-phase porous material at high temperatures, accounting for material deterioration, is presented. Full development of the model equations, starting from the macroscopic balances of mass, energy and linear momentum of single constituents is presented. Constitutive rel...

Two different approaches are presented for the parallel implementation of computer programs for the solution of coupled thermohydromechanical problems. One is an asynchronous method in connection with staggered and monolithic solution procedures. The second one is a domain decomposition method making use of substructuring techniques and a Newton-Ra...

This paper presents the physical, mathematical and numerical models forming the main structure of the numerical analysis of the thermal, hydral and mechanical behaviour of normal, high-performance concrete (HPC) and ultra-high performance concrete (UHPC) structures subjected to heating. A fully coupled non-linear formulation is designed to predict...

 In this paper a new procedure for structural assessment of tunnel constructions during fire is presented. In particular, it consists of two steps: the first one deals with a realistic evaluation of thermal fluxes, both convective and radiative, for the whole tunnel. In the fires recently occurred in some European tunnels, the duration of the fire...

In this paper, a model for the analysis of the behaviour of concrete at temperature largely exceeding critical point of water, is presented. In this temperature range liquid phase, i.e. capillary phase, and gas phase cannot be distinguished and only the latter exists. Consequently, capillary pressure has no more physical meaning above this point an...

This paper presents the numerical procedure used and the results obtained for full coupling between damage and intrinsic permeability in a recently developed model for heat and mass transfer and damage analysis of concrete at high temperature. A formula describing effects of damage on intrinsic permeability is numerically tested. A numerical exampl...

A mathematical model to analyse the hygro-thermal behaviour of concrete as a multi-phase porous material at high temperatures, accounting for material deterioration, is presented. Full development of the model equations, starting from the macroscopic balances of mass, energy and linear momentum of the single constituents is presented. Constitutive...

In the present work an innovative model for analysing the behaviour of concrete in high temperature environment is presented. In such conditions prediction of concrete performance during and after fire exposure is of great practical importance, e.g. in tunnels, as recent fires in major European tunnels have demonstrated. This is particularly true f...

Non-linear deformable porous media with sorption (capillary condensation) hysteresis are considered. An artificial neural network with two hidden layers is trained to interpolate the sorption hysteresis using a set of experimental data. The performance of the ANN, which is applied as a procedure in the FE code, is investigated, both from numerical,...

This paper presents a new numerical model of hygro-thermal phenomena during hardening of fresh concrete elements. The governing equations have been developed by means of the Volume Averaging Theory, considering heat and mass source terms related to phase changes of moisture and chemical reactions of the solid skeleton. The model takes into account...

Dedicated to Professor Roland Lewis on the occasion of his 60th birthday SUMMARY Non-linear deformable porous media with sorption (capillary condensation) hysteresis are considered. An artiÿcial neural network with two hidden layers is trained to interpolate the sorption hysteresis using a set of experimental data. The performance of the ANN, which...

The prediction of concrete performance at high temperature is of great practical importance, in particular for safety evaluation of various concrete structures during fire or in the case of nuclear accident. In such conditions concrete may be subject to spalling phenomena which hazard the integrity of the construction and which may often lead to co...