Marta Sybis

Waterborne epoxy systems enable a polymer phase to be introduced uniformly into cementitious materials, but their curing requirements differ from those of the mineral binder. Cement hydration requires moisture, whereas concentration and crosslinking of the dispersed epoxy phase require progressive removal of water. The study compared ten curing sequences for a mortar containing a two - component waterborne epoxy system at a polymer - to - cement ratio of 15%. All mixtures had identical composition and were evalua ted after 28 days; only the sequence of water, air and thermal curing was changed. The investigated regimes included continuous water curing, continuous air curing, water - to - air sequences of different duration, immediate thermal treatment, and thermal treatment introduced after an initial water - curing stage. Compressive strength was determined on halves of 40 × 40 × 160 mm prisms. Descriptive comparisons were supplemented with one - way analysis of variance at a significance level of 0.05. The curing regime had a statistically significant overall effect on 28 - day compressive strength (ANOVA, p < 0.001). The highes t mean value was obtained after 7 days in water followed by 21 days in air (S2, 28.4 MPa). Similar results were recorded for 14 days in water followed by 14 days in air (S1, 27.5 MPa) and for a sequence consisting of 5 days in water, 1 day at 60 °C and 22 days in air (S7, 26.9 MPa). Continuous water curing produced 19.3 MPa, whereas immediate unprotected thermal treatment followed by air curing gave the lowest value of 16.6 MPa. Relative to continuous water curing, the S2 regime increased the mean strength by 47%. The results show that neither permanent saturation nor premature drying is favorable for the investigated epoxy - cement system. An initial moist period supports development of the cementitious skeleton, while a subsequent air stage creates conditions for polymer - phase formation. Thermal treatment ca n be beneficial only when introduced after adequate initial hydration. The findings support formulation - specific design of curing sequences for waterborne epoxy - modified mortars rather than direct transfer of conventional cement - mortar curing procedures.

Due to the heightened flood risk resulting from climate change, innovative and advanced green building materials are required to enhance the durability and biological resistance of concrete structures exposed to persistent moisture. This study investigates the use of nanosilver-enriched plasticizers as a novel modification of concrete for applications in flood-prone environments. The findings demonstrate that the incorporation of nanosilver enhances the mechanical strength of concrete by reducing surface tension and porosity, thereby enhancing durability and extending service life. Moreover, nanosilver-modified concrete exhibits significant antimicrobial activity, effectively limiting microbial-induced corrosion. Preliminary microbiological analyses showed a reduction of sulfur-oxidizing bacteria (SOB) and sulfate-reducing bacteria (SRB) by 85–92%, as well as a decrease of over 80% in potentially pathogenic microbial genera. This study also highlights the importance of skilled labor and adequate training to ensure the responsible implementation of nanosilver-based technologies in sustainable construction. Overall, nanosilver-enriched plasticizers represent an innovative green building material that supports flood-resilient, durable, and sustainable concrete construction.

Sulfate corrosion is a significant durability issue for concrete used in sewage and hydraulic infrastructure. In sulfate-rich environments, the formation of expansive products (e.g., ettringite and thaumasite) leads to a progressive loss of performance. Unlike conventional protection methods, which rely on surface-applied coatings or impregnation, this study examines the use of water-dilutable epoxy resins as an internal, volume-wide admixture dispersed throughout the concrete matrix to provide whole-body protection. The experimental program evaluated the mechanical performance, microstructure, and sulfate ion ingress/penetration dynamics of resin-modified concretes. The results suggest that using the appropriate amount of resin can limit the penetration of aggressive ions and slow the harmful changes associated with sulfate attack while maintaining the material’s overall performance. Overall, these findings suggest that water-based epoxy admixtures are a promising strategy for improving the durability of concrete in sulfate-exposed environments. They also provide guidance for designing more resistant cementitious materials for modern infrastructure applications.

This paper presents the results of a study on the effect of fully biodegradable modified starch in the form of LU-1400-2 dextrin (denoted d2) and two commercial plasticizers P1 and P2 on selected properties of cement mortars. The studied cement mortar was enriched with 0.25%, 0.30%, 0.35%, and 0.40% d2 dextrin, relative to the weight of the cement. The tests carried out indicate that the addition of dextrin to cement mortars results in an increase in strength (a 9% increase was observed with 0.25% dextrin) and liquefaction of the mixtures. However, commercial plasticizers were found to decrease compressive strength. Starch derivatives are a type of natural plasticizer that is more environmentally sustainable than other types. They are produced from renewable sources, such as plants, and their production generates less waste and involves low greenhouse gas emissions. They are produced from renewable sources, such as plants, and their production generates less waste and involves low greenhouse gas emissions. Preliminary studies suggest that dextrins have great potential as natural plasticizers. The increasing popularity of natural plasticizers in the chemical and construction industries is due to a growing interest in sustainability and concern about the harmful effects of traditional chemical plasticizers.

The increasing production of solid waste and the scarcity of natural aggregates as a matter of fact have made waste recycling a necessity. One such waste, which is generated in large quantities, is slag. However, slag from incineration plants may contain harmful elements that adversely affect the physical, chemical and mechanical properties of cement composites. This study presents laboratory research results on the effect of slag from the Poznan Municipal Waste Thermal Conversion Plant (Poland) on the physicochemical properties of cement composites. The samples were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was shown that the slag analyzed contained significant amounts of aluminum, which had a direct effect on the structure of the concrete. An example of this influence is the release of hydrogen during reactions, which causes swelling and cracking of the concrete and reduces its mechanical strength. The authors emphasize that waste aggregate (slag) can be effectively used in the production of concrete after appropriate processing that reduces the risk of adverse effects.

The manuscript presents research focusing on the adsorption and emulsion properties of starch hydrolysates modified through acetylation, oxidation, and cross-linking. The techniques used in this study included measurements of equilibrium surface tension (du Noüy ring) dynamic surface tension (drop shape analysis), and the preparation and evaluation of emulsion stability (TURBISCAN). The surface activity of the acetylated starch hydrolysates is affected by the degree of acetylation. The acetylated starch 0.02Ac-H exhibited higher surface activity than the more highly substituted derivative 0.1Ac-H. Furthermore, it was shown that the surface activity of the components increased as the acetylated oxidized starch underwent hydrolysis. The fractions collected after 180 min using a membrane with a low separation capability (8 kDa) revealed the highest capacity for reducing surface tension. In binary systems consisting of starch derivatives and surfactants, synergistic effects in reducing surface tension were particularly noticeable in systems containing ionic surfactants. The addition of a cationic surfactant to the modified starch hydrolysate solution (1:6 mol/mol) resulted in a significantly more efficient saturation of the air/water interface. This study demonstrated that emulsions stabilized with modified starch hydrolysates remained stable over time, even when these hydrolysates constituted up to 60% of the emulsifier mixture.

The purpose of the conducted study was to verify whether the use of concrete admixtures with modified starches and starches modified with stabilised silver colloids affects the course of electrochemical potential difference, and hence corrosion, of reinforcing steel in a chloride environment. In the tests, cross-linked starches and products of acid hydrolysis of starch (dextrins) were used as admixtures. The 1-molar aqueous solution of sodium chloride was used as an aggressive environment. The tests consisted of measuring the potential difference generated in the reinforcement corrosion cell on the surface for a period of 60 days and then assessing the risk of corrosion. The effect of the addition of starch derivatives on the properties of cement paste was investigated through a one-way ANOVA analysis of variance followed by post hoc tests. The test results showed that the use of concrete admixtures with cross-linked starches positively affects the passivation of the steel. The likelihood of reinforcing steel corrosion when using distarch phosphate, acetylated distarch phosphate and acetylated distarch adipate admixtures is less than 5%. The results obtained showed an improved effect on the passivation of reinforcing steel in cement composites. Additionally, concrete samples may have microbicidal properties.

The conducted research aimed to evaluate the influence of admixtures of various modified starches on the rheological properties of cement composites and their influence on the compressive strength of hardened cement mortars. The study involved 17 different modified starch admixtures. Using a rheometer, the values of viscosity and tangential stresses were determined depending on the shear rate, and were subsequently used to determine the yield point and plastic viscosity of cement slurries. The next parameters tested were the flow of fresh cement slurry and the compressive strength of hardened cement composite. The highest fluidisation was recorded for retentate LU-1420-0.5%Ac-R, an increase of 82%. The conducted tests led to the conclusion that admixing cement composites with modified starches changes the rheological parameters and the compressive strength of cement composites. The highest strength gains occurred for the admixtures of retentate LU-1412-R (increase of 25%). Declines in compressive strength were noticed in the retentate LU-1422-R (decrease by 13%) and the retentate OSA-2.5%-R (decrease of 17%). The admixture of starch hydrolysate significantly decreases the yield point of slurries, which in turn may contribute to the fluidisation of concrete mixes and the reduction of mixing water. The lowest values were obtained for retentates LU-1420-0.5%Ac-R (decrease of 94%), and LU-1412-R (decrease of 93%). It was found that the consistency and compressive strength of cement mortars are affected by both the type of modification and the length of the chemical chain of starch.

Growing interest in the use of natural organic compounds in the production of green concrete with the use of plasticizers has been particularly noticeable in the literature of recent decades. Starch is an attractive material due to its abundance, the low cost of sourcing it, and its biodegradability, biocompatibility, and susceptibility to modification. The objective of the study was to evaluate the effect of starch hydrolysate additives on the physicochemical properties of cement composites and concrete. Compressive strength tests and cement slurry rheology measurements were carried out for water–cement ratios from 0.40 to 0.50 and for amounts of added dextrin from 0.0 to 0.7% in relation to the cement weight. The dextrins used were characterized in terms of their viscosity, polymerisation degree, and surface activity in air/water systems. Conducted research indicates that even the minimum content of dextrin increases the fluidization of cement mixes (the flow diameter increased by 67.5% compared with the mixture without the admixture), enables the reduction of mixing water, and contributes to the compressive strength of cement mortars. A further decrease in the w/c ratio to the value of 0.40 resulted in an increase in the strength value of up to 67.9 MPa, which provided a 40% increase in strength. The degree of the polymerisation of added dextrin is seen as having an effect on the physical parameters of the cement mortar; the shorter the polymer chain of the studied dextrin, the more packed the adsorbent layer, and the greater the flow diameter of the cement mortar.

The leading theme of the paper was to study, how the use of lightweight concrete based on waste aggregates, characterized by significant mechanical strength and increased thermal insulation, affects the properties of building partitions and contributes to possible economic savings, so as to properly design and select materials required for the construction process. The work presents the composition of lightweight concrete samples made of waste lightweight aggregates as well as their physical and mechanical properties. It includes calculations concerning floor loading and heat transfer coefficient of building partitions made of the presented lightweight concretes. Calculations provided the basis for assessing the impact of particular parameters on compressive strength and thermal insulation of walls and floors. The paper additionally describes concretes made of waste aggregates in the form of lytag (Pollytag) and slag. Based on the research, it was found that concrete containing Pollytag had the lowest density value and thermal conductivity coefficient. These parameters translated into reduction in the weight of the slab in question by more than 40% and allowed to save 25% of steel compared to an analogous plain concrete slab. The decrease in heat conductivity coefficient did not result in a significant increase in thermal insulation of building partitions.