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Carbonation of concrete is a complex phenomenon, depending on many factors, including the heterogeneity of concrete, which results in an uneven carbonation front. The assessment of the depth of the carbonation front depends on the measurement technique adopted. The article summarizes the standard techniques for measuring the depth of carbonation and proposes an alternative measurement technique based on the measurement of the fields of the carbonated and noncarbonated surfaces, and then converting to the averaged depth of carbonation. For an example sample, the results obtained with different standard techniques and the proposed off-standard technique were compared.

Concretes with dispersed reinforcement are increasingly used in structural engineering. The basic source of knowledge on their application and design are the Model-Code 2010 guidelines. These guidelines, however, apply mainly to steel rebar reinforcement and are not fully sufficient in the analysis of the load-bearing capacity of elements made of concrete with dispersed reinforcement. Therefore, scientific research in this field is carried out continuously. The main goal of our work is to provide experimental data for the calibration of constitutive models of the cracking mechanics of concrete with reinforcement in the form of steel and polypropylene fibers. This article shows the possibility of using the digital image correlation system (DIC) to achieve this goal. The method of sample preparation and the method of conducting the tests were modeled on the recommendations contained in the PN-EN 14651: 2007 standard. The tests were carried out on prismatic elements with a notch loaded in a three-point bending setup. The results of standard strength tests are presented in the form of column graphs and tables. As an extension, the results of calculations of energy dissipated in fracture process are given. Moreover, the experimentally obtained graphs of the relationship between the force, displacement and crack opening were presented, which were supplemented with the images of crack development obtained with the use of DIC. The development of the crack net is characterized not only qualitatively but also quantitatively as a function of deflection or crack mouth opening displacement. Conclusions concerning the adopted research methodology and the tested materials are presented at the end of the article.

NASA has revealed that they plan to resume manned missions and ensure the permanent presence of people in the so-called habitats on the Moon by 2024. Moon habitats are expected to be built using local resources—it is planned to use lunar regolith as aggregate in lunar concrete. Lunar concrete design requires a new approach in terms of both the production technology and the operating conditions significantly different from the Earth. Considering that more and more often it is assumed that the water present on the Moon in the form of ice might be used to maintain the base, but also to construct the base structure, the authors decided to investigate slightly more traditional composites than the recently promoted sulfur and polymer composites thermally hardened and cured. Numerous compositions of cement “lunar micro-mortars” and “lunar mortars” were made and tested to study rheological properties, namely, the consistency, which largely depend on the morphology of the fine-grained filler, i.e., regolith. For obvious reasons, the lunar regolith simulant (LRS) was used in place of the original Moon regolith. The used LRS mapped the grain size distribution and morphology of the real lunar regolith. It was created for the purpose of studying the erosive effect of dusty regolith fractions on the moving parts of lunar landers and other mechanical equipment, therefore, it simulated well the behavior of regolith particles in relation to cement paste. The obtained results made it possible to develop preliminary compositions for “lunar mortars” (possible to apply in, e.g., 3D concrete printing) and to prepare, test, and evaluate mortar properties in comparison to traditional quartz mortars (under the conditions of the Earth laboratory).

The research study forms a part of the “Management of municipal water waste treatment plants potential by-products of sewage sludge ash type, as active or non-active additions to Portland cement-based binders” project’s outcomes (H2020-MSCA-IF-2016-746830). Based on the applied techniques characteristics (non-isothermal and non-adiabatic differential micro-calorimeter, SEM/EDS and XRF analysis), this study comprises the very first stage for a sustainable conversion of each of the considered 190114 and 190107* waste streams into a value-added by-product for specific constructive applications. Provided technical requirements regarding the designed cementitious products handling and suggested industrial application are focused on the early performance of the tested for quality and consistency, pastes, mortars and concretes. In detail, the obtained physical–chemical parameters show substantial differences of the original waste streams regarding their technological origin, seasonability and geographical localisation. Consequently, the calorimetric curves exhibit diverse early chemistry of the produced cements, showing the considerable variations in mineral nature (siliceous, aluminous) or hydraulic factor contents (reactive silica, SiO2r−, and reactive alumina, Al2O3r−) of the observed pozzolanic activities. Setting retarding phenomenon and shrinkage reducing effects are also carefully discussed. All the calorimetric and pozzolanic activity related data is contrasted with two other reference materials, fly ash and granulated blast furnace slag, standard behaviour.

Calculation of the carbon footprint of cement concrete is a complex process including consideration of the phase of primary life (components and concrete production processes, transportation, construction works, maintenance of concrete structures) and secondary life, including demolition and recycling. Taking into consideration the effect of concrete carbonation can lead to a reduction in the calculated carbon footprint of concrete. In this paper, an example of CO2 balance for small bridge elements made of Portland cement reinforced concrete was done. The results include the effect of carbonation of concrete in a structure and of concrete rubble after demolition. It was shown that important impact of carbonation on the balance is possible only when rubble carbonation is possible. It was related to the fact that only the sequestration potential in the secondary phase of concrete life has significant value.

The article presents an in-depth analysis of the mechanism leading to protective coating failure and concrete corrosion in the wastewater treatment plant. Losses of protective epoxy coatings over large areas and deep concrete deteriorations with a maximum depth exceeding 2 cm were found after just 2 years of service on the concrete elements of pre-treatment tanks. The research program consisted of design documentation analysis, environmental tests, laboratory concrete and coating tests, and in-situ diagnostics. Environmental tests included determining temperature distribution over pre-treatment tank walls, analyzing wastewater composition, and determining CO2, H2S, and NH3 concentration in wastewater vapors. Laboratory concrete and coating tests were conducted on cores taken from tank walls and consisted of: compressive strength and freeze-thaw resistance tests, sulfate-ion content and pH distribution over depth, phase composition research, and SEM observations. In-situ diagnostics included pull-off and rebound hammer tests. Substances marked in the wastewater were in the ranges typical for municipal sewage. Wastewater itself did not constitute a significant threat to coated tank walls. The main threat to concrete sourced from the microbial activity of sulfur-reducing and oxidizing bacteria, resulting in successive H2S release from wastewater and H2S oxidation to H2SO4 on tanks walls (microbially induced concrete corrosion). The research results indicate that concrete used in the construction of wastewater treatment plant tank walls was properly designed, placed, and cured. The root cause of coating failure lied in its high vapor permeability and lack of full resistance to sulfuric acid, which resulted in the fast diffusion of SO42− ions from the coating surface into the concrete structure, causing its expansion and leading to coating delamination and concrete destruction.

This paper examines the influence of polyacrylic superabsorbent polymers (SAP) on the properties concerning chloride diffusion in cementitious materials. The conducted study investigated the influence of SAP on chloride diffusion in concretes of the initial w/c = 0.4 (for which the changes in compressive strength due to the SAP presence were negligible). The impact on the diffusivity of concrete of several variables was analyzed: the material characteristics of SAP, additional water added to the concrete to make up for the amount of water stored in the SAP structure, and the method of SAP dosing to the mix (either in a non-saturated form or in a hydrogel form). We found that, in the case of modifying concrete with polyacrylic SAP of a median particle size in dry conditions of 330 µm and without additional water, the coefficient of chloride ion diffusion was reduced to 65% of the reference value. The negative influence (increase) of increasing w/ctot by the amount of water initially entrained by SAP on the chloride diffusivity of concrete was identified. The conducted study indicates the premise of the mechanism of the water release from SAP in cementitious composites.

The preliminary stage of asphalt mixture production involves the drying and dedusting of coarse aggregates. The most common types of coarse aggregates used are limestone and basalt. In the process of drying and dedusting the dryer filter accumulates large quantities of waste in the form of mineral powder. This paper introduces an investigation into limestone powder waste as a potential microfiller of polymer composites. Physical characteristics such as the granulation the of powder collected from the filter - in terms of the season of its collection and the type of input materials used - were analysed. A scanning electron microscope (SEM) was used for the investigation described within this paper. The obtained results were compared against those of other materials which can be used as polymer composites microfillers.

The research assesses the effect of selected type II additives on concrete carbonation. Siliceous fly ash, FASi, is used as a cement component or cement replacement in concrete; ground granulated blast furnace slag, GGBS, is used as a cement component; fluidised bed fly ash, FFACa, is used as a cement replacement; calcareous fly ash, FACa, is used as a fine aggregate replacement; and, silica fume, SF, is used as a cement or fine aggregate replacement. The results show that waste mineral additives increase the depth and rate of carbonation, while extending water curing time increases the resistance to carbonation of concrete containing additives, significantly in GGBS cement and concretes with w/c ratio above 0.35. The results show that in the case of concrete with mineral additives, such as ash and slag, the course of the initial water curing of concrete is a very important factor influencing resistance to carbonation. The application of waste mineral additives to concrete should include the lowest possible w/c ratio and the lengthiest possible water curing, immediately after the commencement of construction activity.

This paper addresses the tensile and flexural strength of HPC (high performance concrete). The aim of the paper is to analyse the efficiency of models proposed in different codes. In particular, three design procedures from: the ACI 318 [1], Eurocode 2 [2] and the Model Code 2010 [3] are considered. The associations between design tensile strength of concrete obtained from these three codes and compressive strength are compared with experimental results of tensile strength and flexural strength by statistical tools. Experimental results of tensile strength were obtained in the splitting test. Based on this comparison, conclusions are drawn according to the fit between the design methods and the test data. The comparison shows that tensile strength and flexural strength of HPC depend on more influential factors and not only compressive strength.

The paper presents the case study of the degradation of architectural precast concrete elements on the facade of St. Michael the Archangel church in Warsaw. The background of the contemporary precast non-standard prefabrication was presented with the examples of polish recent applications. The GPR (ground penetrating radar) method was used in determining the location of reinforcement in the precast elements in the degraded façade. The conceptions of repair were analyzed and the reasons of the destructions of the precast elements.

The subject of the article is the analysis of the influence of factors related to the course of concreting on the quality of the reinforced concrete element. The problem was discussed on the example of columns with an unusual narrow cross-section (18x80 cm). The characteristics of the surface defects of tested columns are presented and their causes are discussed. The basis of discussion were observations and in-situ tests of concrete mix performed during concreting similar elements in similar conditions. The potential effects of defects in terms of component durability were also considered.

The effectiveness of internal curing of cement composites with the use of SAP depends, among others, on its chemical composition and its granulation. However, the interaction between hydrogel and other components of the concrete hasn’t been fully investigated. The aim of the presented research was to investigate the impact of cement/aggregate particles friction during mixing on the properties of water-saturated SAP. Novel mechanism of SAP hydrogel fragmentation was identified as one of the causes of differences in internal curing efficiency dependent on SAP state (water-saturated/non-saturated). Due to mixing process the surface area of tested SAP increased approx. 10 times. It was found that dosing SAP in a hydrogel form results in more homogenous SAP distribution within cement matrix. Such a modification of SAP dosing process enables to increase the efficiency of concrete internal curing. It was confirmed by obtained results for concrete mechanical strength and freeze-thaw resistance.

Cemented stabilized rammed earth (CSRE) is a building material used to build load bearing walls from locally available soil. The article analyzes the influence of soil mineral composition on CSRE compressive strength. Compression tests of CSRE samples of various mineral compositions, but the same particle size distribution, water content, and cement content were conducted. Based on the compression strength results and analyzed SEM images, it was observed that even small changes in the mineral composition significantly affected the CSRE compressive strength. From the comparison of CSRE compressive strength result sets, one can draw general qualitative conclusions that montmorillonite lowered the compressive strength the most, beidellite also lowered it, but to a lesser extent. Kaolinite lightly increased the compressive strength.

This paper examines the influence of dosing method and material characteristic of superabsorbent polymers (SAP) used for internal curing, on the selected concrete properties. A new method of introducing SAP into the concrete mix and its impact on the shrinkage and compressive strength of concrete was studied. It was shown that the method of dosing SAP to the concrete mix and the differences in the properties of the tested SAPs have a significant impact on the course of changes of selected properties of the tested concrete composites. In order to compare tested series with each other and with other published results on the subject, a new method of including SAP mass content in the concrete mix, as a percentage of absorbed mixing water, was presented. The effectiveness of internal curing using different types of SAP under different dosing methods was presented as a percentage difference in tested concrete properties between modified series and reference series.

The aim of this research is to determine the influence of waste perlite powder quantity on rheological properties of polymer–cement mortar mixture. Influence of dosing sequence of waste perlite powder on mortar mixture properties was especially taken into consideration. In the research, eight mortar mixtures were prepared using different quantities of perlite powder in mortar and by using different dosing sequence of mixture components. During the research, the influence of waste perlite powder on consistency and workability of mortar mixture was evaluated. By analyzing the various dosage sequences of the ingredients, the problem of difficult homogenization of the mortar and excessive dusting of the waste perlite powder were investigated. The obtained results show that changing the dosing moment of the key component – waste perlite powder – can influence technological properties of polymer–cement mortars.

The aim of the research was to test the ability of vinyl-ester concrete containing waste powder to resist chemical attacks of sulfuric acid and sodium hydroxide. Tested composites contained mineral dust remaining after preparation of aggregates for mineral-asphalt composites. It was experimentally confirmed that from the point of view of chemical composition, granulometry, specific surface area, and density, the waste dust appeared to be a good substitute for commercial quartz powder used in polymer concrete. The evaluation of chemical resistance of polymer concrete with waste dust was done in terms of mass loss and change in compressive strength of composite after its exposition to aggressive media. The tests were performed according to the modified method described in guidelines for the precast elements production. Analysis of test results showed that even the high substitution of quartz powder with waste mineral dust (up to ~85%) in vinyl-ester concrete is possible and such composite presents high mechanical properties (though in some cases it requires using larger amounts of polymer) – not much worse than in case of non-modified composites.

The polymer concretes characterize with very high chemical resistance, achieved through the use of high-quality polymers and aggregates. The paper discusses the possibility of using the waste perlite powder, the very fine by-product of manufacturing and use of expanded perlite, as the component of polyester concrete (PC), in terms of the durability of concrete under chemical attack. Partial substitution of original microfiller (usually the quartz or calcium carbonate powders) of polymer concretes by the perlite powder is one of the potential ways of disposing this waste. In the paper the polyester concretes of various quantitative compositions, thus various waste perlite powder content, were exposed to the chemically aggressive environment. The compositions were designed on the basis of statistical design. The tested composites contained the unsaturated polyester used as the binder, the standard sand and crushed granite gravel of fraction 2-4 mm used as the basic aggregates and mix of quartz and perlite powders used as the microfiller. The specimens of concretes were exposed to the solution of potassium hydroxide of concentration of 5% for 60 days. The measure of polyester concrete resistance to potassium base were changes in mass and changes in the mechanical strength (flexural and compressive strength) of specimens subjected to chemical attack in comparison to specimens chemically unloaded. Additionally the visual inspection of the specimens outer surface and fracture surface after the flexural strength test were conducted.

In this paper there are presented results of research carried out for establishing the most favourable scenario of curing of the Polymer-Cement Concrete (PCC). The general recommendations for PCC point to the need of alternating conditions of curing of PCC. Polymer-cement concrete should be first cured in the wet conditions for effective hydration of Portland cement and then in air-dry conditions for polymer setting. According to the literature, the often accepted curing regime of PCC covers 5 days of wet curing and then the air-dry curing until the time of testing. According to the European Standards, the wet period should last 3 days. However, the authors` experiences show that the aforementioned scenarios is not the optimum one. The studies presented in this paper are the part of the larger research program, which – according to the authors` intention – should lead to the establishing of the optimum curing regime for PCC. The tests were carried out using two types of polymer modifiers: two-component epoxy resin and water dispersion of polyacrylates, introduced into the cement concrete mix. The following properties were accepted as the criteria of evaluation of PCC curing effectiveness: compressive strength, tensile splitting strength, surface tensile strength (by pull-off method), wear resistance, water penetration under pressure. These properties were evaluated after 28 days of curing according to the various regimes. The tests showed that the extension of the wet curing period beyond 5 days was favourable for the technical properties of PCC. The establishing of the optimum time of wet curing, however, needs further research. Also, some conclusions were formulated about the usefulness of the various properties as the criteria of PCC curing efficiency evaluation.

Currently, a worldwide dynamic rise of interest in using soil as a construction material can be observed. This trend is evident in the rapid rise of the amount of standards that deal with soil techniques. In 2012 the number of standards was larger by one third than five years prior. To create a full standardization of the rammed earth technique it is necessary to take into account the diversity of used soil and stabilizing additives. The proportion of the components, the process of element production and the research methods must also be made uniform. The article describes the results of research on the compressive strength of rammed earth samples that differed from each other with regards to the type of loam used for the mixture and the amount of the stabilizer. The stabilizer used was Portland cement CEM I 42.5R. The research and the analysis of the results were based on foreign publications, the New Zealand standard NZS 4298:1998, the American Standard NMAC14.7.4 and archival Polish Standards from the 1960’s that dealt with earth material.

The aim of the article is mathematical modelling of the carbonation process that has been based on results of research conducted both in accelerated and natural conditions. The article covers short characteristic of carbonation, its processes and effects. Also critical review of articles that concern carbonation mathematical models was included in the paper. Assuming the self-terminating nature of carbonation the hyperbolic model of carbonation was formulated. Such a model describes the carbonation progress as the process unlimited in time but with the restricted range in concrete depth that is limited by the value of a model asymptote. Presented results cover research on carbonation of concrete with a different water-cement ratio and different types of binders and duration times of early curing. Investigations have been conducted as accelerated (1% concentration of CO2) as well as in long-term exposures in natural conditions. The obtained results confirmed statistically that hyperbolic model is a well-founded approach when the modelling concrete carbonation process is concerned

In EN 13670:2009 standard: Execution of concrete structures there are general rules of moisture curing of concrete in structures. In the standard 4 classes of concrete curing are described. Determination of curing class depends on required level of compressive strength immediately after curing (percentage of required characteristic strength after 28 days). Time of curing depends on rate of strength development and concrete surface temperature. In the standard there is a lack of information about influence of curing class on concrete durability characteristics. The main condition to obtain durable concrete is proper curing regime. Not cured on improperly cured concrete has weakened surface layer. Extremely faults in curing process could lead to defects visible on the concrete surface. More often defects are latent inside the concrete and could be revealed during exploitation, leading to durability reduction. The main effect is increase of surface layer porosity (reinforcement cover) and decrease of its protective properties and tightness. Consequently worsening of mechanical properties could be observed as well as water-tightness, frost resistance, chemical aggression resistance, carbonation resistance and diffusivity of chloride. The analysis shown in the paper are the result of 3-yers long investigation conducted by authors, which main goal was to determine appropriateness and way to include durability requirements in designing of curing class according to EN 13670:2009. Thawing-freezing resistance, scaling with salts resistance, depth of water penetration under pressure and absorptivity were adopted as the basic durability factors. Concretes with different cement types, different rate of compressive strength development, air-entrained and non-air-entrained were tested. Time of curing was differentiated in the range of classes 1,3,4 following standard EN 13670:2009 requirements. Practical conclusions were formulated which allows to consider durability presumptions in technological requirements contained in concrete works specifications.