Izabela Hager and Tomasz Tracz
This article has no abstract.
The influence of metahalloysite addition on tobermorite formation studied by X-ray powder diffraction and scanning electron microscope
This paper presents the results of the studies carried out in the model systems and concerning the tobermorite synthesis with an addition of metahalloysite. Quartz sand and quicklime were the main raw material constituents. The mixtures in the form of slurries underwent hydrothermal treatment with an addition of metahalloysite (5%, 10%, 15%, 20% and 30%) for 4 hours and 12 hours. The resultant composites were analysed for their phase composition using X-ray powder diffraction. The microstructure was examined using the Scanning Electron Microscope. Tobermorite was the principle reaction product. When 30% metahalloysite was added to the mixture containing CaO and SiO2, the formation of katoite was found.
Application of acrylic-based coatings for concrete protection
The paper presents a description of acrylic-based polymers used in civil engineering for concrete protection. Some information on chemistry and properties of the acrylic coatings is included together with current trends in coating technology. Moreover, the paper shows test results, that is barrier properties and SEM observations of a commercial elastic acrylic-based polymer subject to artificial weathering for 1000h. The studies showed that the weathering did not change carbon dioxide permeability of the tested coating and its influence on water vapour permeability of the material was also very small. The test results show that an assessment of coating performance based only on barrier properties is not enough
Tomasz Domański and Kamil Kmiecik
Probability calibration of deformation factor for timber roofs in the Polish mountain zones
The resistance parameters of timber material structures decrease with time, depending on the type of load and timber classes. Strength and Modulus of Elasticity reduction effects, referred to as creeprupture effects, due to long term loading at high stress ratio levels are known for many materials. Timber materials are highly affected by this reduction in strength and deflection with duration of load. Characteristic values of load duration and deformation factors are calibrated by means of using probabilistic methods. The reliability is estimated by means of using representative short-and long-term limit states. Time variant reliability aspects are taken into account using a simple representative limit state with time variant strength and simulation of whole life time load processes. The parameters in these models are fitted by the Maximum Likelihood Methods using the data relevant for Polish structural timber . Based on Polish snow data over 45 years from mountain zones in: Zakopane – Tatra, Świeradów – Karkonosze, Lesko – Bieszczady, the snow load process parameters have been estimated. The reliability is evaluated using representative short – and long –term limit states. The deformation factor kdef is obtained using the probabilistic model.
Adam Zielinski and Maria Kaszynska
Influence of the w/c ratio and aggregate composition on the autogenous shrinkage in self-consolidating concrete
Paper presents the analysis of shrinkage development in selfconsolidating concretes (SCC). Concretes were cured for 28 day in an insulated environment. The shrinkage was tested on 35x150x1150 mm samples. The specimen had the same volume as ring specimen proposed in the ASTM method of testing the susceptibility of concretes to cracking caused by the restricted radial shrinkage. Linear deformation of concrete samples was measured in constant periods of 500 s using dial gauges with digital data loggers. Conducted tests showed the influence of w/c ratio of 0.28, 0.34, 0.42 and aggregate composition on the development of the autogenous shrinkage in self-consolidating concretes. Additionally, rheological properties of the concrete mixes were tested and compressive and splitting strength was determined. Conducted research allowed to evaluate the influence of w/c ratio and natural aggregate composition on the development of autogenous shrinkage in different stages of curing of SCC.
Beata Jaworska, Paweł Łukowski and Jerzy Jaworski
Influence of cement substitution by calcareous fly ash on the mechanical properties of polymer-cement composites
The aim of the presented research was to determine the influence of cement substitution with calcareous fly ash on the mechanical properties of polymer-cement composites. Coal combustion products such as calcareous fly ash have been already used in traditional cement composites as a part of cement and considered potential additions for concrete but its introduction into polymer-cement composites is still under preliminary investigation. The morphology of fly ash causes problems with its compatibility with polymer-cement binders but its insertion into those building materials is another way to utilize mineral combustion products that are cumbersome in storage and recycling. The influence of the mineral addition on polymer-cement composites containing 20% of polymer was especially taken into consideration. Mechanical properties of polymercement mortars modified with calcareous fly ash were tested after 28 and 90 days of curing. As a part of preliminary study, activity index of mineral addition was determined. Polymer-cement composites containing calcareous fly ash were characterized by higher flexural and tensile strength comparing to standardized mortar, even for the mortars containing 40% of mineral addition. The negative effect of the polymer-cement composites modification with calcareous fly ash was especially observed on the compressive strength of this composites.
Arina Shaybadullina, Grygory Yakovlev, Valery Grakhov, Irina Polyanskikh and Yuliya Ginchitskaya
Multifunctional decorative coatings based on cement-silicate binder
A facade decorative coating has been developed that is based on sodium silicate and Portland cement and modified with a complex ultra-and nanodispersed admixture including titanium dioxide, expanded perlite sand, and multi-walled carbon nanotubes dispersion. The advantage of the produced coating is using Portland cement as a silicizer instead of the conventionally used zinc oxide. Adding ultra-and nanodispersed admixtures to the cement-silicate composition leads to the structural modification of the matrix of the binder composition along with the formation of a more durable coating (up to 4-5 times compared with the existing analogues) and the possibility of absorbing man-made electromagnetic radiation up to 38%. Expanded pearlite sand in the silicate coating provides a relief surface when applied on the base. The cement-silicate composition for coating facades is shown to have the following physical and technical characteristics: the viscosity measured with Viscometer-6 is 29 sec; the hydrogen index of the medium pH=12.33; the film resistance to static effect of water is 8 hr; the paint consumption for a two-layer coating is 200-400 g/m2; the adhesion (the cross-cut test) is 1 point; the conventional light-fastness is 4-5 points; the frost-resistance of the silicate coating is 75 cycles. The developed facade cement-silicate coating can be applied on the surface of silicate-containing materials. The cost effectiveness of using the multifunctional protectivedecorative coating has been proved in comparison with similar compositions.
Przemysław Czapik and Zdzisława Owsiak
Chemical corrosion of external stairs – case study
On the basis of examinations of the efflorescences formed on the concrete surface, an attempt was made to analyze the sources of concrete corrosion without entering inside the construction. The concrete stairs revealed the symptoms of leaching, as a result of alkali-aggregate reactions developing beneath the surface. As a result of this corrosion process and the carbonation propagating from the concrete surface, the carbonate efflorescences were found. Their phase composition was determined by X-ray diffraction. In order to identify whether the efflorescences were the results of the alkali-silica reaction or alkalicarbonate reaction, the microstructure was investigated using the scanning electron microscope together with energy dispersive spectroscopy.
Michał Łach, Kinga Korniejenko, Maria Hebdowska-Krupa and Janusz Mikuła
The Effect of Additives on the Properties of Metakaolin and Fly Ash Based Geopolymers
The main motivation of research work is connected with environmental issues. The production of the most important building material of the 20th century - Portland cement technology is associated with significant environmental pollution. The process requires very high temperature and it is energy consuming. During the manufacturing also takes place emission of significant amounts of carbon dioxide and highly toxic nitrogen oxides into the atmosphere These factors show that new solution in this area is required. The most promising alternative is inorganic polymer (geopolymer) technology.
The main objective of the presented research work was to design a new composite for practical applications, especially in construction industry. The paper presents the results of research of geopolymer composites based on geopolymer binders made of metakaolin and fly ash with the addition of titanium oxide and aluminum-calcium cements (including mainly calcium monoglinate) in amount of 4 and 6% by weight. Research methods applied: tests for mechanical properties (compressive strength tests), scanning microscopy investigations (SEM) and X-Ray Diffraction (XRD).
The results show that the addition of aluminum-calcium cements (including calcium monoglinate) significantly increases the compressive strength of geopolymers. Geopolymers based on fly ash with the addition of 6% calcium-aluminum cement with a calcium monoglinate content above 69% are characterized by compressive strength above 50 MPa, while geopolymers from metakaolin with the same additive were characterized by compressive strength above 80 MPa.
Małgorzata Linek, Piotr Nita, Paweł Wolka and Wojciech Żebrowski
Usefulness of porphyry and amphibolites as a component of concrete for airfield pavements
Coarse aggregate used as part of cement concrete is of primary significance for the obtained parameters of hardened concrete. In case of concretes intended for airfield pavements, the application of granite grit is recommended. Alternative to this type of aggregate in the form of porphyry and amphibolites aggregate was suggested. In order to assess the suitability of different aggregate types for concrete mixes, their bulk density, absorbability, polishing resistance, abrasion and crushing resistance were determined. Also, the internal structure of the suggested aggregates and its influence on changes of hardened concrete composite structure were subject to the assessment. The influence of aggregate type on the structure of cement matrix and contact areas between the matrix and aggregate grains were specified. The observed changes, in case of the internal structure of concretes based on porphyry and amphibolites aggregates, with reference to granite aggregate, resulted in changes of mechanical and physical parameters. Analyses included the determination of bulk density, absorbability, compression, bending and splitting resistance. According to the obtained laboratory test results, the significant influence of the aggregate type applied to the mix on parameters of hardened concrete, with regard to the application thereof to the airfield pavements was proved.
Wojciech Węgrzyński and Piotr Turkowski
Material properties and the energy balance in standardized fire testing
The origins of standardised fire testing can be traced back to 1870’s, and the origin of the standard temperature-time curve to 1917. This approach, based on a 19th-century intuition is still in use up to this day, to design the 21st-century structures. Standardized fire-testing ultimately disregards the conservation of energy in the fire, as in every test the resulting temperature of the test must be the same (precisely as the temp.-time curve). To maintain this, different amount of heat is required in every test, which means that every time a different fire is modelled within the furnace. The differences between furnace fire sizes are ignored in the certification process, but can be interesting for fire researchers to understand how different materials behave in fire conditions. In this paper, Authors explore this topic by investigating the energy balance within the furnace, and comparing different fire tests together.
Balázs Nagy and Tamás K. Simon
Energy and hygrothermal performance of builtin mineral wool thermal insulations
Ewa Sudoł, Dawid Dębski, Renata Zamorowska and Barbara Francke
Impact resistance of external thermal insulation systems
In the paper the results of an experimental program intended to determine factors influencing the impact resistance of the External Thermal Insulation Composite Systems (ETICS) were presented. For the research the systems based on polystyrene have been chosen. The insulation material was faced with a rendering consisting of base coat reinforced with standard or armored glass fibre mesh and silicone or silicone-silicate binders as finishing coats. The influence of various renderings components was evaluated with respect to resistance to hard body impact and resistance to hail. The test results were discussed in the context of the possible impact level on ETICS in use.
Barbara Francke and Robert Geryło
Inverted roof insulation kits and their durability
In the paper there was analyzed a mechanism of loss of performance properties of inverted roof insulation kits resulted by moisture increase of the insulation layers. This problem is very important in such systems because the thermal insulation is placed above the waterproofing layer and is not protected against water absorption. Abovementioned problem is more and more common in the course of building’s utilization in Polish climate conditions. Because inverted roof kits are based on extruded polystyrene (XPS) and expanded polystyrene (EPS), those materials have been used in tested samples. The results of laboratory tests showed the phenomenon and its effect on durability and sustainability of roof covering performance. It was also found that the biggest influence on the increase of moisture in the thermal insulation layer has not the long term water absorption by immersion but freeze –thaw cycles.
Julita Krassowska and Marta Kosior-Kazberuk
Failure mode in shear of steel fiber reinforced concrete beams
Experimental tests were carried out to assess the failure model of steel fiber reinforced concrete beams. Experimental research was focused on observing changes in the behavior of the tested elements depending on the amount of shear reinforcement and the fiber. Model two-span beams with a cross-section of 80x180 mm and a length of 2000 mm were tested. The beams had varied stirrup spacing. The following amounts of steel fibres in concrete were used: 78.5 kg/m3 (1.0%) i 118 kg/m3 (1.5%). Concrete beams without fibres were examined at the same time. The beams were loaded in a five-point bending test until they were destroyed. Shear or bending capacity of the element was observed. Fibre reinforced concrete beams were not destroyed rapidly, but they kept their shape consistent under load. Larger number of diagonal cracks with a smaller width were observed in fibre reinforced concrete beams. Failure of concrete beams without fibres was rapid, with a characteristic brittle cracking. Steel fibres revealed the ability to transfer significant shear stress after cracking in comparison to plain concrete.
Izabela Hager, Katarzyna Mróz and Tomasz Tracz
Concrete propensity to fire spalling: testing and observations
This article presents results of fire spalling tests on small concrete slabs and studies of material parameters that may increase its occurrence. Experimental techniques enabling to study and determination of material features are presented and discussed. Experimental studies on spalling behaviour of elements were carried out on seven different concrete mixes with constant content of cement paste and mortar. Research aimed at determining influence of the following parameters: w/c ratio (0.30; 0.45; 0.60), cement type (CEM I, CEM III) and type of aggregates (riverbed gravel, granite, basalt) on fire concrete spalling. Paper discusses also the influence of cold rim that forms while testing slab-like element is subjected to one-side heating.
Jacek Sudyka, Lech Krysiński, Adam Zofka, Marek Pszczoła and Piotr Jaskuła
High frequency impulse ground penetrating radar application in assessment of interlayer connections
Ground Penetrating Radar (GPR) technique is commonly used in the nondestructive evaluation of pavement structures. In particular, this method is used to estimate thicknesses of pavement layers as well as it can be utilized in advanced studies of pavement structures. The device presented in this paper comprise the high frequency impulse antennas that allow for investigating the interlayer zones in terms of their electromagnetic properties (e.g. dielectric constant). In some cases these electromagnetic responses can be suitable in the assessment of layer bonding in the pavement structure. This paper discusses the assessment of the quality of asphalt pavement interlayer bonding with the use of high frequency GPR techniques. The preliminary laboratory measurements were performed using an impulse antenna in the zero-offset configuration combined with the large-scale models simulating an idealized horizontal delamination. These measurements allowed to estimate the antenna sensitivity to detect interlayer connection under dry and wet conditions. Analysis of collected results led to formulating practical conclusions regarding critical limitations of the measuring system and adequate methods of signal processing and interpretation.
The field investigations consisted of the GPR measurements along selected road sections and collection of the core samples at the locations associated with the specific reflexes. Inspection of the cores provided some real insights into the structure of different delaminations associated with characteristic reflexes. Analysis showed the reflection properties are able to expresses some important features of the interlayer zone, such as delaminations, presence of alien material at the interface, insufficient compaction occurring at the base of layer, and water penetration.
Dawid Łątka and Piotr Matysek
Assessment of the compressive strength of lime mortar in the joints of brick walls - case study
The paper presents the test results of lime mortar compressive strength in the joints of brick walls. The tests were carried out with the Double Punch Test (DPT) method and with the use of an impact penetrometer (penetrometric test PT) on original samples taken from the structure of a building erected in the 1880s. The obtained results have shown that the predictions of the mortar compressive strength using both methods were very consistent (the difference 6%). The penetrometric method also made it possible to assess the homogeneity of the mortar in the direction of the wall thickness.
Aneta Nowak-Michta and Brygida Kabat
Physical properties of post-process fly ash from TWTP Krakow
Fly ashes from eco-incinerator according to the Art.7 of the Act of December 14, 2012 on waste are a hazardous waste. The growing amount of this type of waste generates a problem in terms of their management. They are a post-process waste, so their chemical composition is not constant and their quality is not very high. In addition, a high content of heavy metals with different concentrations may adversely affect the properties of these ashes. The physical properties of fly ashes originating from the TWTP in Krakow in the light of the requirements of PN-EN 450-1 are analysed in the article. The aim of the paper is a preliminary assessment, based on the tests carried out on three random ashes, to check if there’s a possibility of utilisation of this type of waste in concretes. The results of physical properties examination showed that they are coarse ashes with a several percent moisture content. They meet the requirements of PN-EN 450-1 in terms of the impact on the initial setting time and soundness. They cause an increase in the mortar's water demand. Their compression activity index after 28 days is 63-70%, and after 90 days 56-67% and do not meet the standard requirements (75% after 28 days and 85% after 90 days).
Ewelina Kłosek-Wawrzyn and Paweł Murzyn
Assessment of preliminary suitability of Fe-and Cr-rich waste material for the production of building ceramics
This paper presents laboratory research on assessment of preliminary suitability of stainless steel waste material in building ceramics production. Application of the waste material in building ceramics production is innovative and might be environmentally friendly way to utilize it and to improve/modify the properties of the ceramic products. The waste was used as an additive to kaolinite-illite and montmorilloniteillite clay type. Selected properties of ceramics materials such as water adsorption, firing shrinkage, open porosity, apparent density, frost resistance, compressive strength and leaching of chromium and iron were determined. Improvement of the mechanical properties of the fired material and its colour intensification were observed. The studies confirmed the possibility of the utilization of this kind of waste material in production of building ceramics.
Justyna Zapała-Sławeta and Zdzisława Owsiak
The impact of lithium nitrate on the physical and mechanical properties of Portland cement
The effectiveness of lithium nitrate as a chemical additive which reduces the negative effects of alkali aggregate reaction was subject to research by scientists in many centres around the world. The literature data on the impact of lithium nitrate on the physical and mechanical properties of cements are rare. Without a precise definition of the impact of lithium nitrate on the cement properties, it is extremely hard to determine its real advantages in practical usage. In this paper, studies were undertaken to assess the impact of LiNO3 on the properties of pastes and mortars with Portland cement. The rate of hydration of the cement with lithium additive was examined by isothermal calorimetry, measurements of setting time and phase composition of cement pastes in the initial stages of hydration. The influence of the admixture on the compressive strength development of mortars after 2, 7 and 28 days of hardening was also researched. Results indicate that lithium nitrate accelerates the early hydration of Portland cement, affecting the precipitation of hydration products. The compressive strength of mortars with lithium admixture decrease after 28 days, although 2 an 7-day strength were greater than the control mortars.
Paweł Łukowski, Ali Salih and Joanna J. Sokołowska
Frost resistance of concretes containing ground granulated blast-furnace slag
The paper deals with the influence of addition of ground granulated blast-furnace slag (GGBS) on the frost resistance of concrete. GGBS is a valuable modifier of concrete, having the latent hydraulic properties and particularly improving the chemical resistance of concrete. However, the performance of concretes with blast-furnace slag under freezing and thawing action is still not explained fully and remains a subject to discussion. The authors have investigated the concretes containing various amounts of GGBS and the portland cement CEM I, with various values of water to binder ratio, with and without the use of air-entraining admixture. The results of research show that the addition of blast-furnace slag causes some worsening of the frost resistance of concrete. The extent of this worsening depends on the water to binder ratio and the aeration of the concrete. However, even under the least favourable conditions, the concretes with GGBS addition have met the requirements of frost resistance after 200 cycles of freezing and thawing, given in the Standard PN-B-06265.
Julia Marczewska and Wojciech Piasta
The impact of air content on the durability of concrete under combined sulphate and freezethaw attack
The aim of the study was to determine the optimal air content in concretes subjected a combination of exposure conditions. Five series of concretes with different air contents were tested. The article reports the experimental results of the combined sulphate expansion and freeze-thaw attack in ordinary Portland cement concrete. Some of the concrete samples were immersed in a 5% sodium sulphate solution for nine months, and then frozen in air and thawed in water. The resistance of concrete to plain freezing and thawing was also tested. In order to compare the degree of concrete damage in both environments, long-term linear deformations (expansion) and compressive strength of concretes were investigated. To explain the complex damaging process the air-void structure in concretes was investigated. The changes in concrete microstructure after storing in sodium sulphate solution were observed under the scanning electron microscope (SEM). The prior sulphate attack significantly accelerated the deterioration of non-air-entrained concrete and air-entrained concrete with low content of air voids. Optimal air entrainment will protect concrete from the harmful effects of the interaction of sulphate attack and freezethaw damage.
Christos Tassos, Kosmas Sideris, Alexandros Chatzopoulos, Nikolaos Pistofidis and Emmanouil Chaniotakis
Influence of cement type on carbonation of concrete mixtures
This research aims to investigate the influence of cement type to carbonation. For this purpose mixtures of four different cement mortars and eight different concretes that have been prepared with four different cements were left exposed for one year in open air in northern Greece. Results indicate that the type of cement influences the carbonation rate. Concrete mixtures produced according to the definitions of EN 206 standard perform lower service life against carbonation induced corrosion if the choice of the cement type is not carefully examined.
Wioletta Raczkiewicz, Wioletta Grzmil and Justyna Zapała – Sławeta
Impact of the air-entrained concrete with the blast-furnace slag cement on the intensity of reinforcement corrosion process
The concrete cover has significant impact on the intensity of reinforcement corrosion process in reinforced concrete elements. Depending on the type of corrosion risk different types of cement are recommended for concrete. In conditions of chloride corrosion, due to, for example, the use of de-icing agents in winter, it is recommended to use concrete with cement containing granulated blast-furnace slag. The risk of chloride corrosion due to the use of de-icing agents is often additionally associated with the frost and repeated freezing and thawing actions of structural elements. The liquid freezing in the pores of concrete increases its volume, which causes the increase of internal stresses and leads to cracks in the concrete cover increasing the diffusion of chlorides. In order to reduce this phenomenon the introduction of air-entraining admixture is beneficial. The paper presents the experimental results that allow to determinate the effect of the air-entraining admixture addition on the intensity of reinforcement corrosion in concrete with blast-furnace slag cement. The tests were carried out on two groups of reinforced concrete specimens subjected to freezing and thawing cycles in 3% NaCl solution. One group of specimens was prepared with the airentraining admixture addition and the other without it. The electrochemical tests of the reinforcement corrosion activity, based on the measurements of the corrosion current density were curried. The phase composition by X-ray diffraction and microstructure of concrete under the scanning electron microscope (SEM) coupled with the X-ray microanalyser (EDS) were examined. The results allowed to comprehensively assess the effect of airentrained concrete with blast-furnace slag cement on the degree of reinforcement corrosion risk in concrete caused by the simultaneous action of chlorides and frost.
Naim Sedira and João Castro-Gomes
Study of an alkali-activated binder based on tungsten mining mud and brick powder waste
Blends of Tungsten mining waste mud (TMWM) and brick waste powder (BP) with different dosages were used as precursors for the study of a new binder obtained by alkali-activation. The synthesis was obtained at 60ºC curing during the first 24 hours and at 20°C during the remaining period. A combination of sodium hydroxide (SH) and sodium silicate (SS) solutions was used with SS/SH weight ratio equal 1.5. The solid precursors/liquid activators weight ratio equal to 4. And the modules SiO2/Na2O increase with the increasing of BP dosages 5.21 and 5.59 for dosages 10% and 50%, respectively. Mineralogical characterisation of raw materials was carried out by X–ray diffraction (XRD). The effect of the dosage of BP on the compressive strength and pore size distribution of the new binder was investigated from 24 hours up to 28 days. The pore size distribution was obtained mercury intrusion porosimetry (MIP). The increase in the dosages of BP, between 10 to 50%, was followed by an increase in compressive strength, from 25 to 59 MPa, for all the tested ages. The binder matrix become more dense and compact with the gradually increase of BP dosages, as found out by MIP.
Amal Abdelaziz, Chun-Hsing Ho and Matthew Snyder
Evaluating the Influence of Polymer Modified Asphalt Binders on Low Temperature Properties
Low temperature cracking is one of the most common distress types in asphalt concrete pavements, particularly in cold regions. Many factors influence the behaviour of asphalt concrete pavements at low temperatures, such as the applied traffic load, environmental conditions and material characteristics. Asphalt binders are one of the primary factors that influence material properties. The purpose of this study is to compare the performance of two types of asphalt binders: styrene-butadiene-styrene (SBS) modified asphalt binder and unmodified asphalt binder in resisting low temperature cracking. The study was conducted in Flagstaff, located at the area of Northern Arizona, in the United States. Asphalt samples were collected from the paving sections and were compacted and trimmed into small beams. Bending Beam Rheometer tests were performed, using the trimmed specimens at temperatures of -6°C, -12°C and -18°C. Based on the results of the study, it was concluded that, SBS modified asphalt binder performs better in resisting low temperature cracking, compared to the unmodified binder. Based on the study outcomes, it is recommended to use SBS polymer modified polymers in areas subjected to severe cold weather events to maximize the life span of asphalt concrete pavements.
Elzbieta Horszczaruk, Roman Jedrzejewski, Jolanta Baranowska and Ewa Mijowska
Application of the nanoindentation method in assessing of properties of cement composites modified with silica-magnetite nanostructures
The results of investigation of the cement composites modified with 5% of silica-magnetite nanostructures of the core-shell type are presented in the paper. The nanoindentation method employing three-sided pyramidal Berkovich indenter was used in the research. The mechanical properties and microstructure of the modified cement composites were evaluated on the basis of the values of hardness and indentation modulus measured inside the cement matrix and in the aggregate-paste interfacial zone. The results were compared with those obtained for the reference composites without nanostructures. The positive influence of the presence of silica-magnetite nanoparticles on the tested properties was found out.
Towards the utilization of waste glass powder in sustainable cement based overlays
The article focuses on the possibility of utilizing waste glass powder in cement based overlays for sustainable construction. In the work, a study was carried out on the evaluation of the influence of waste glass powder, which modifies the overlay, on its adhesion to a concrete substrate. The waste glass powder was added in various amounts in relation to the binder mass. The adhesion tests were conducted using the commonly known pull-off method. The preliminary test results are presented and discussed in the article.
Teresa Stryszewska and Marta Dudek
Chemical testing of post-process ashes from municipal waste combustion
The results of the study presented in the paper are a part of the research project about possibility of utilization of fly ashes obtained from municipal waste combustion in production of cement binders. The main goal was to determine possibility reduction of Cl- and SO42- contents in ashes by leaching. The scope of the examination included SEM observations along with an EDS analysis of chemical composition. Preliminary results show that the major problem is the presence of heavy metals such as Cr, Ni, Cu etc.
Walid Deboucha, Nordine Leklou and Abdelhafid Khelidj
Hydration degree development of blast furnace slag blended cement pastes using thermogravimetric Analysis (TGA)
The hydration degree assessment of slag blended cement pastes with three different replacement levels (10, 20 and 40%) and two finenesses (400 and 500 m2/kg) was investigated. The hydration degree was evaluated by using a modified TG method suggested by Deboucha et al., 2017. This method builds on the activity coefficient concept, which makes it possible to assume the amount of mineral additives that contribute to hydration reactions as well as cement. Results showed that the efficiency of blast furnace slag in developing hydration degree was conditioned by its level of replacement and fineness.
Tomasz Piotrowski and Piotr Prochoń
Influence of water to solid ratio on mechanical properties of GBFS-based geopolymer foam concrete
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 100x100x100 cubes) have been prepared and volume density, bending, compressive strength tests have been performed. In a result an optimized lightweight GBFS-based geopolymer foam concrete was obtained, characterized by 1.8 kg/dm3 volume density, 2.6 MPa bending strength and 51.8 MPa compressive strength measured on beams and 44.1 MPa compressive strength on cubes.
Philippe Poullain, Elodie Paquet, Sébastien Garnier and Benoît Furet
On site deployment of 3D printing for the building construction – The case of Yhnova
The University of Nantes has developed a 3D printing technique (BatiPrint3DTM) dedicated to the construction of the walls of a house. This innovative on site construction technique is based on the deposition of two layers of expansive foam used as a formwork for a third concrete layer. It allows to build at the same time the structure and the insulation. This new construction technology has first been developed at the laboratory, but rapidly, we decided to deploy it on site, in order to demonstrate its technical viability. We present the technology Batiprint3DTM and the demonstrator YhnovaTM, a 95m2 social dwelling built for the social landlord Nantes Métropole Habitat (NMH).
Daria Jóźwiak-Niedźwiedzka, Mariusz Dąbrowski, Karolina Gibas, Aneta Antolik and Michał A. Glinicki
Alkali-silica reaction and microstructure of concrete subjected to combined chemical and physical exposure conditions
Salt solutions are used to ensure safe driving conditions during winter. NaCl deicer is the most often used brine in Polish climatic zone. The chemical effects of this type of chloride-based deicer in wetting and drying (WD) and temperature cycles on concrete need to be better understood. This research was focus to study the microstructure of air-entrained pavement concrete after combined chemical (10% of NaCl) and physical (WD and 60°C) exposure conditions. The adopted WD and temperature regime was designed to verify the hypothesis that regularly alternating wetting and drying cycles with external alkali supply from deicer salt will provoke the Alkali-Silica Reaction (ASR). The aggregates varied their origin and mineralogical composition. The microscopic examination was carried out on concrete specimens using SEM with EDX. The microscopic analysis has shown that main reason for concrete deterioration during cyclic chemical and physical exposure conditions was both physical influence - WD cycles and the chemical influence – ASR (primarily, the fine aggregate which lead to form of alkali-silica gel). The expansive gel was shown to be capable of destroying the test specimens. Also differences in mineralogical composition of coarse aggregates influenced on the concrete prism expansion due to ASR.
Krzysztof Kuchta and Izabela Tylek
Rational application of hot finished rectangular hollow sections in steel structures
Steel hollow sections are manufactured as both welded and seamless elements. The influence of manufacturing technology causes tubes made from the same carbon-manganese steel to differ significantly in terms of their mechanical properties. The cold-formed welded tubes are produced from a steel strip that is roll formed and welded; both technological processes take place at room temperature. This profile type is characterised by less favourable mechanical properties and by much higher inhomogeneity within the cross-section than the seamless tube. However, due to the lower cost of manufacturing, welded tubes are much more often used in building structures than seamless ones. After thermomechanical treatment, the welded tubes, which are referred to as “hot finished”, have almost the same mechanical properties as seamless tubes. However, hot finished sections are more expensive than welded ones; therefore if they are to be applied in the structure in a reasonable way, higher unit cost should translate into an appropriate increase of the load bearing capacity. The aim of the paper is to indicate the application areas of hot finished rectangular hollow sections in which their use is economically justified.
Maria Kaszyńska, Marcin Hoffmann, Szymon Skibicki, Adam Zieliński, Mateusz Techman, Norbert Olczyk and Tomasz Wróblewski
Evaluation of suitability for 3D printing of high performance concretes
The article presents overview of additive manufacturing for concrete structures. Study focuses on specific tests used to determine suitability of high performance mixes for 3D printing. The tests include determination of compressive strength and evaluation of printing speed, extrudability and overall surface quality. Tests were performed on a High-Performance Concrete mix with fine natural aggregate up to 2 mm. Mineral additives such as silica fume and fly ash, and superplasticizer were added to obtain proper consistency. The tests were performed using specially designed site consisting of Cartesian robot and pumping module. The design of printed paths were tailored for specific tests. The evaluation of pump performance was made by measuring pumped mix volume in time. The determination of correct pumping speed was made based on the visual quality of the printed layers. Study determines also the ability to print multilayered structures and printability window of proposed mix.
Chun-Hsing Ho, Anas Almonnieay, Khin Kyaw and Phoo Myat Sandy Maung
Assessing the Performance of Concrete Containing Recycled Glass on Tensile Splitting Strength and Resistance to Alkali Silica Reaction
Using recycled glass in concrete applications decreases the amount of glass in landfills and substitutes for expensive aggregates in the concrete mix. However, there has been a concern on recycled glass with smooth surfaces that would result in a drop in strength and in particular a reduction of an already low ductility. Thus, in many design aspects, the use of recycled glass in concrete is limited up to 30% by weight due to concern on concrete strength reduction. The current manufacturing technology in the recycling glass has been grown and evolved through which recycled glass has been processed to exhibit the following features: basically zero water absorption, excellent hardness (great abrasion resistance), high durability to resist extreme weather conditions, etc. The paper challenges the currently used recycled glass mixtures and presents new mix design principles for concrete mixed with 10%, 20%, 30%, 50%, and 100% recycled glass as replacements of nature sand and Portland cement to assess (1) strength changes and (2) resistance to alkali silica reaction (ASR). Aggregate, water reducer, hydration stabilizer, mid-range water reducer, fiber, and viscosity modifier were prepared with varying dosages of recycled glass. A series of scanning electron microscope (SEM) imaging were performed to evaluate the resistance of recycled glass specimens to ASR. The paper concludes that the use of recycled glass as an alternative aggregate and cement binder in the concrete mixtures show promising performance in both tensile splitting strength and ASR.
Marcin Kulesza, Dawid Dębski and Jadwiga Fangrat
Effect of redispersible polymer powder on setting time of thin-bed mortars
The aim of work is to describe and to complement the existing knowledge on the effect of redispersible polymer powder on the setting time of cement mortar as measured by means of ultrasonic apparatus. The mortars were simple mixtures of filler in the form of quartz sand, Portland cement CEM I 42.5 R as binder and methyl hydroxyethyl cellulose. The mortar additives were two commercially available redispersible polymer powders in an amount of 0-5% of total weight. The chosen polymers had different chemical structure: styrene-acrylic copolymer (SA), vinyl acetate-ethylene copolymer (ET), and minimum film forming temperature (MFFT). The amount of water was constant and equal to 20% of the total weight of the mortar. Conclusions: - even the small amount of redispersible polymer powder added to the cement mortar has a significant influence on mortar’s initial and final setting time and this effect strongly depends on the percentage of the additive, - the chemical structure of the studied redispersible polymer powders did not influence the behaviour of the whole chemical system, - the further studies on technical properties, such as mechanical strength and permeability are planned in order to find more information on the structure of hardened mortar.
Justyna Kuziak, Piotr Woyciechowski, Rafał Kobyłka and Aldona Wcisło
The content of chlorides in blast-furnace slag cement as a factor affecting the diffusion of chloride ions in concrete
Blast-furnace slag cement (CEM III) has a wide range of acceptable Cl- content according to EN 197-1: 2012. This makes possible to use alternative fuels for the production of cement, which can increase the chlorides content in the clinker. However, it raises several new research problems, among them the problem of increase of the risk of Cl- penetration intensity due to the higher concentration of chlorides in cement, presented in this paper. Studies have shown that after a short hardening time (28 days) the rate of diffusion of chloride ions increases slightly with the increase in the content of chlorides in the cement CEM III, but after full stabilization of concrete properties (1 year), the content of chlorides in cement CEM III practically does not affect the diffusion rate of chloride ions in concrete.
Mateusz Sitarz, Izabela Hager and Joanna Kochanek
Effect of High Temperature on Mechanical Properties of Geopolymer Mortar
The advent of modern aluminosilicate binders has resulted in practical uses for fly ash, which belongs to the group of secondary mineral raw materials; this provides an interesting alternative to cementitious binders, which have a large carbon footprint. Geopolymers mineral binders with a growing range of applications in construction. Their inorganic, amorphous structure endows them with better resistance to high temperature compared to cementitious binders. In this study, the alkaline activation of aluminosilicate Połaniec Fly Ash made it possible to obtain noncementitious material with compressive strength of 18.5 MPa. The article presents the results of a comparison of characteristics of geopolymer mortar and Portland cement mortar after thermal exposure.
Krystian Brasse, Tomasz Tracz, Tomasz Zdeb and Piotr Rychlewski
Influence of Soil-Cement Composition on its Selected Properties
The paper discusses the results of mechanical and technological tests of soil-cement composites made with cohesive soil. The compositions of analysed soil-cement mixtures differed in terms of their cement paste volume fractions and water-cement ratios. Limiting values of these technological parameters that enable the application of the soil-cement mixtures obtained in real life conditions for the purposes of the Deep Soil Mixing (DSM) method were determined. Based on the test results obtained, it was found that mechanical properties of the materials analysed were very sensitive to changes in their compositions. Variations in the volume fraction of cement paste within the range analysed caused mechanical properties to change even by an order of magnitude.
Low cement content SCC (Eco-SCC) – the alternative for ready-mix traditional concrete
Self-Compacting Concrete (SCC) is often regarded for in-situ applications as a more expensive and less environmentally friendly version of traditional concrete for use in places where the latter is highly inconvenient for various reasons. To counteract this belief, a new type of SCC has been proposed, called Eco-SCC or green-SCC. In comparison to typical SCC this building material has lower powder content resulting in low cement content and a slightly lower paste volume. The disadvantage of this approach is high water content and low viscosity resulting in high vulnerability of fresh concrete to sedimentation. Additionally, comparing to EN-206 limits, mixes with too low cement content are often obtained. This is why a research program has been undertaken to check the possibility of obtaining fresh Eco-SCCs of higher viscosity, thereby fulfilling all EN-206 requirements. It was possible to obtain concretes of C25/30-C35/45, SF2, VF2, PL2, containing 265-300 kg/m3 of cement and 165-190 kg/m3 of water owing to the use of limestone powder and typical rounded aggregate of local origin with very low sand to a total aggregate ratio of s/a = 0.4. Based on Global Warming Potential (GWP) analysis, a modification of Eco-SCC definition is proposed: Eco-SCC is an SCC having cementitious materials volumetric content no greater than 100 dm3/m3 (or mass content no greater than 315 kg/m3).
Marta Choinska, Hayder Al-Khazraji, Nathan Benkemoun and Abdelhafid Khelidj
Influence of tensile cracking and of aggregate size on concrete permeability
The aim of this study is to investigate the interaction between crack opening (COD), aggregate size and gas transfer in concrete submitted to mechanical loading in the Brazilian splitting tensile test. The lab-made devices have been developed to investigate physical phenomena during loading and to provide data to validate a developed mesoscale hydromechanical model by the same authors, based upon a 3D lattice approach to represent the heterogeneity of the material . Experimental studies has been carried out on five materials with different aggregate sizes. The results emphasize that permeability of mortar increases with cracking following a sigmoid law, with the most important kinetics due to passingthrough connected crack growth, after nonsymmetric one-face crack initiation. Furthermore, the obtained results highlight that permeability increase, due to aggregate size, may be separated from permeability increase due to tensile cracking: for all the five materials tested results fall on the same master sigmoid curve. This behaviour law represents a strong advantage for concrete modelling.
Roman Jaskulski and Wojciech Kubissa
Lightweight concrete with copper slag waste as sand substitution
The paper presents results of tests of lightweight concrete made with copper slag waste material as fine aggregate (fraction 0 – 2 mm) and two types of light aggregate (fractions > 2 mm). Six series of concrete with three w/c ratios (0.50, 0.55 and 0.60) and two variants of cement content (200 kg/m3 and 300 kg/m3) were manufactured. Reference concretes were also prepared in which copper slag waste was replaced by the same mass of river sand. To maintain similar densities of mixtures with copper slag in comparison to those with sand mutual proportions of both lightweight aggregates were modified. On concrete specimens compressive strength was tested as well as the open porosity was determined by drying to stable mass at 65°C. The concrete bulk density in saturated and dried state was also determined using hydrostatic weighing. The obtained results were compared with the results of the reference concrete tests. Results have shown that replacing sand with copper slag waste in lightweight concrete does not negatively affect their strength but may slightly increase their porosity.
Application of ceramic dust as a modifier reducing the extent of rheological deformations in airfield pavement concrete
The article presents material solution based on the application of ceramic dust as concrete mix component intended for airfield pavements. Material composition is intended for the application on the selected areas of pavement exposed to the influence of imposed thermal loads intensifying the stress strain state of concrete slabs. Due to the nature of loading of these parts it is necessary to reduce the extent of registered rheological deformations. Concrete containing dust additive is distinguished by more favourable porosity properties, more consistent cement matrix without visible discontinuities and with the formed different hydration products. Diversification of internal micro structure of cement concrete using the suggested dust has significant influence on the improvement of mechanical, physical and performance parameters. Also, assessment of the applied dust influence on the extent of the registered rheological deformations was presented. The analyses included concretes curing in standard conditions and concretes subject to thermal cycles representing the destructive influence of imposed loading. The obtained laboratory test results prove clearly the validity of the suggested solution. Reducing the extent of deformations is derivative of favourable changes observed in internal structure of concrete composite. Better formed contact areas provide the increased concrete parameters and consequently influence extending concrete durability.
Danuta Barnat-Hunek, Sylwia Duda, Monika Garbacz and Grzegorz Łagód
Hydrophobisation of mortars containing waste polyurethane foam
This paper investigates the physical and mechanical properties of mortars modified with waste polyurethane foam (WPF) and the influence of hydrophobising agents on the physical characteristics. The sand was substituted with WPF (2-4 mm grain size) in the mortars which consisted of 5, 10 and 15% of foam, respectively. The contact angle of lightweight mortars was determined (θw) in the function of time, prior to and after the frost resistance test. The surface free energy characterizing the wettability and adhesion of mortars under normal conditions and following frost erosion was calculated with Neumann’s method based on the obtained data. The structure of mortars, adhesion of lightweight aggregate to cement paste and the structure of thin hydrophobic film were demonstrated by means of scanning electron microscopy. The mortars subjected to hydrophobisation process revealed a slight mass change caused by freezing and thawing processes: 0.1% for methyl silicone resin, 2.1% for alkyl-alkoxy-silane, and 9.2% for the samples which were not hydrophobized. On average, the contact angle of the standard mortars was 3 times lower than the one of hydrophobic material. The best results illustrating the efficiency of hydrophobisation were obtained for methyl silicone resin.
Analysis of protective features of concrete in precast prestressed floor slabs (HC type) against chloride penetration
This paper describes protective features of concrete used in precast prestressed floor slabs against chloride penetration. HC-500 hollow core slabs are designed for constructing ceilings in skeletal buildings with reinforced concrete. Material and structural protection used in slabs determines the acceptable range of using HC slabs, taking into account durability of floors during their normal exploitation. These slabs can be used in buildings where environmental conditions affect them according to the following exposure classes: X0, XC1, XC2, XC3 (according to standards: EN 206-1: 2003 , EN 1992-1-1:2004 ). Values of diffusion coefficient for concrete collected directly from precast prestressed HC-500 slabs, were determined during short (24h and 48h) tests accelerated by the electric field. In those tests we used a thermodynamic migration model and a reverse equation of chloride migration in concrete. Taking into consideration values of diffusion coefficient and diffusion equation, the time required for chloride concentration to reach critical value for reinforcement and the thickness of reinforcement cover were established under the condition that the structure durability was subjected to the exposure class XD3 (chapter 4 of the standard PN 1992-1-1).
Miroslav Komljenović, Nataša Džunuzović and Violeta Nikolić
Resistance to external sulfate attack - Comparison of two alkali-activated binders
Durability of binders, mortars and concretes in aggressive environments is of crucial importance for their commercial application. In this paper the resistance to external sulfate attack of two different alkaliactivated binders (AABs), based either on blast furnace slag (BFS) or fly ash/blast furnace slag (FA/BFS) blend, was compared with two different commercially available Portland cement (CEM II) blended either with BFS or with FA and BFS. Comparison of sulfate resistance was based on compressive strength testing (the loss of strength) of mortar samples exposed to sodium sulfate attack up to 180 days and samples cured under controlled conditions for the same period of time. Furthermore, the evolution of microstructure of alkali-activated binders and pH of sodium silicate solution during testing were also analyzed. Despite different gel chemistry being involved, both alkali-activated binders based either on BFS or FA/BFS blend showed excellent resistance to external sulfate attack and even better than selected Portland cements tested under the same experimental conditions.
Elżbieta Janowska-Renkas and Jolanta Kowalska
Use of fly ash from fluidized bed boilers in clinker-slag-ash based binders
The study presents the state of knowledge regarding physical and chemical properties, as well as trends for application of fly ashes from combustion in fluidized bed boilers in building materials. Clinker - slag - ash based binders were tested that contained up to 40 mass % of fly ashes from combustion in fluidized bed boilers. It was demonstrated that fluidized bed combustion fly ashes (FBC fly ash), apart from granular blast furnace slag, could be the ingredient of low clinker Portland cements (ca. 20% by mass). These cements, compared to CEM I Portland cement, have higher water demand and durability in the corrosive environment, and a lower compressive strength value. Based on test results of binders with various content of blast furnace slag and fly ash, the clinker - slag - ash based binder was singled out, which demonstrated the higher durability in the corrosive environment. It was found that production of clinker - slag - ash based binders was possible in the strength class 32.5 even with 30% by mass of FBC fly ash content.
Elżbieta Janowska-Renkas, Jolanta Kowalska, Grzegorz Janus and Agnieszka Kaliciak
Cement-fly ash mortars durability, with fly ash from fluidized bed boilers and conventional combustion, exposed to aggressive environment influence
The study shows results of research on the aggressive environment impact (1, 3 and 5% HCl solution) on durability of cement mortars with fraction from 30 to 45% by mass of fly ashes from the fluidized bed combustion (FBC fly ash) and conventional fly ashes used separately and in the form of a mixture. The impact of aggressive environments on durability of cement and ash mortars was tested for aperiod of 365 days, by testing the compressive strength, linear changes, mass loss and porosity. It was demonstrated that mortars with the content of FBC fly ashes, after 365 days of tests showed the higher resistance to aggressive environment impact. It is confirmed by e.g. their higher compressive strength, and thus the reduced total porosity. Reduction of total porosity content (<50 nm) was accompanied by the increased compressive strength, which in the aqueous environment was in favour of cement mortars, and in the aggressive environment in favour of cement and ash mortars. It was demonstrated that the content of pores < 200 nm was lower for mortars with FBC fly ashes and mixtures of ashes regardless of environment the mortars were stored in. A beneficial impact of FBC fly ashes was found on physical properties of mortars, i.e. reduction of the shrinkage, lower mass loss and reduced destruction of mortars in the acid corrosion environment. That effect was especially beneficial for the mortar with higher (45% by mass) content of FBC fly ashes, regardless of aggressive character of the environment.
Paweł Woliński, Piotr Woyciechowski, Beata Jaworska, Grzegorz Adamczewski, Daniel Tokarski, Tomasz Grudniewski, Marta Chodyka and Jerzy Antoni Nitychoruk
The influence of the mineral additives on the carbonation of cement composites
In practice, it is usually assumed that the durability of basic structural elements should not be less than the expected durability of the building. Reinforced concrete constructions, designed and made with quality requirements, are durable. However, each reinforced concrete structure, from the moment it is made, is gradually degraded, and one of the reasons for its destruction is often the corrosion of the concrete and hence the reinforcement. For the long-term use of reinforced concrete constructions, the most important thing is that a thin protective layer on the steel surface protects the reinforcing steel from rusting. One of the most common causes of corrosion in the reinforcement is the damage of this layer as a result of the carbonation of the concrete cover. The rate of carbonation depends on many factors, such as concrete compactness, concentration of CO2, concrete moisture, content of free calcium dioxide, content of mineral additives, etc. When the carbonated layer reaches the steel reinforcement layer, protection of steel from corrosion ceases to exist. The aim of the presented research was to determine the influence of mineral additives used as a compound of concrete on the carbonation of concrete and polymer-cement composites.