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This study aims to determine the durability of concrete, in which plastic chips originating from the casing and enclosures of small electronic items are used as a part of coarse natural aggregate. The following three amounts were used: 50%, 70%, and 90% of the aggregate by volume. The concretes were tested after 28 days of standard curing as well as after exposure to physical (25 freeze-thaw cycles and 25 wet-dry cycles) and chemical (HCl, MgSO4, and NaOH) aggressive influences. Durability was evaluated based on changes in both flexural and compressive strength after exposure. The results of the corrosion resistance tests confirm the different types of behavior of the samples, depending on the relative proportion of the plastic aggregate. In terms of a comprehensive evaluation of the experiment, the greatest potential was found in concrete with 50% plastic chips, which can be defined as lightweight-low strength concrete. However, the specific compressive strength (strength to density ratio) increased with increasing amounts of plastic aggregate, which is a good standpoint for recycling this waste if specific applications are identified that can accept the technical limits of this material while using the positive parameters that could be useful for the application.

This paper presents experimental research on expanded clay aggregate concrete. The aim of the investigations was to determine if the pre-wetting of expanded clay aggregate has an effect on the freeze-thaw durability of the expanded clay aggregate concrete. Five concrete series based on the same concrete mix design were made and tested. The degree of pre-wetting of the aggregate was varied: dry aggregate was used in the first series, aggregate with a moisture content of 10% was used in series IA and IB and aggregate with a moisture content of 25% was used in series IIA and IIB. Also the approach to the production process was varied: in series A the water contained in the aggregate was taken into account in the global water-cement ratio (consequently a reduced amount of water was added to the mix), whereas in series B the nominal amount of water was added to the mix (as in the case of dry aggregate). The freeze-thaw resistance criterion was based on the assessment of the decrease of compressive strength and increase in weight loss after exposure to freeze-thaw cycles. The expanded clay aggregate concrete's strength and mass decrements caused by freeze-thaw cycling were used as the measure of its freeze-thaw resistance. The investigations have shown that the pre-wetting of expanded clay aggregate has an effect on the freeze-thaw durability of the expanded clay aggregate concrete. The differences of concrete compressive strength decrease related to freeze-thaw durability may be 2 to 5 times greater when inadequate method of calculating mixing water for concrete is used.

In the Loess Plateau in Northern China, repeated freeze-thaw (FT) cycles deteriorate the strength and structure of loess as a foundation soil, resulting in the instability or failure of supporting structure. Lignosulfonate is an eco-material, utilized as an effective and nontraditional stabilizer to improve the engineering properties of metastable soils. A series of laboratory tests, including unconfined compression tests, cyclic loading-unloading tests and scanning electron microscopy, on calcium lignosulfonate (CL)- and sodium lignosulfonate (SL)-stabilized loess were performed to investigate the stabilization effect, deterioration mechanisms of the FT cycles, and the resistance to FT cycles. Two traditional stabilizers, quicklime (QL) and sodium silicate (SS), were selected, and the engineering properties of QL- and SS-stabilized loess were compared with those of CL- and SL-stabilized loess. The results showed that the strength values of CL- and SL-stabilized loess specimens decreased by 34.2% and 50% respectively, after 20 FT cycles, whereas those of the traditionally SS- and QL- stabilized specimens decreased by 85.3% and 82.87%, respectively. The elastic moduli of SL- and QL-stabilized loess specimens decreased by 22.1% and 92.0%, respectively. The mean energy dissipations of nontraditionally treated specimens also decreased significantly less than those of traditionally treated specimens. Overall, the results showed CL and SL had better stabilization effects on engineering properties of loess than QL and SS, and their stabilized loess specimens exhibited stronger resistance to FT cycles. The study findings demonstrated the significant potential of lignosulfonate for extensive application in cold loess areas.

This paper evaluates the use of waste material mixtures including marble dust and scrap tire rubber the stabilization of fine-grained soils in order to remove the effects of freeze-thaw cycles. In this study, a fine-grained soil material was stabilized by using waste material mixtures. Natural and stabilized fine-grained soil samples were subjected to freeze-thaw cycles under different curing periods. After the freeze-thaw cycles, compressive strength tests were performed to investigate effects of waste material mixtures on the freeze-thaw resistance of fine-grained soil samples. The experimental results showed that the samples of fine-grained soil stabilized with waste material mixtures have high freeze-thaw durability as compared to unstabilized fine-grained soil samples. Consequently, we conclude that waste material mixtures including marble dust and scrap tire rubber, can be successfully used as an additive material to enhance the freeze-thaw durability of fine-grained soils for soil stabilization in the geotechnical applications.

Owing to its exceptional physical properties, silica aerogel is regarded as an attractive candidate material for building insulation applications; however, the widespread adoption of silica aerogel is limited by its inherently brittle nature and related sub-micrometre dust release. In this paper, the poor mechanical properties of silica aerogel were improved by combining the silica phase and cementitious materials to reach engineering strong composites and maintain relatively low thermal conductivity. The mechanical properties, durability (freeze–thaw resistance, water resistance and drying shrinkage) and thermal conductivity of the silica aerogel–cement composites were comprehensively studied. The composites show improved mechanical properties as compared to pure silica aerogel, but this decreases with the increase of silica aerogel content. With respect to the durability, surprisingly, the silica aerogel can efficiently improve the frost and water resistance of the composite, which might be benefited by the strong hydrophobicity of the silica aerogel. The optimal performance of the composite is observed at 60 vol.% aerogel loading. The thermal conductivity, compressive strength, flexural strength and bonding force are 0·065 W/(m/K), 3·81 MPa, 2·23 MPa and 0·27 MPa, respectively, and the drying shrinkage of the composite is only 0·12% after 90 d.

The freeze/thaw phenomenon is of interest for the field of transport infrastructure through the degradations it produces in the structure of construction elements. The climatic specificity of Romania on the one hand and the exposure to aggressive environments of construction elements in transport on the other hand, determine the importance of studying this phenomenon, its mode of action/propagation and also prevention and maintenance to ensure the functionality of buildings in transport infrastructure. Currently, in the Romanian regulations [*], the assurance of sustainability is done, as in most national annexes for the application of EN 206 [1] in Europe, by a descriptive approach (concrete “designed to last”) referring to (with mandatory status) a series of requirements of the concrete composition (water / cement ratio, minimum cement dosage, entrained air, freeze/thaw resistant aggregates, etc.) and to the compressive strength (concrete compressive strength class) in depending on the classification of the element in a certain exposure class “X”. The support of this descriptive national approach was based on the analysis of a large number of results obtained in a complex experimental program carried out by Technical University of Civil Engineering Bucharest, by analyzing the results obtained by laboratory tests on “candidate” cements and cements “reference” (having a good behavior and traditional use) as well as “in situ” tests/determinations on construction elements made with both categories of cements and maintained in specific environments. At European level, performance approaches to sustainability have made clear progress. The development of accelerated laboratory experimental methods, the establishment of performance criteria, classes of resistance to various environmental actions and the link between them and the classes of exposure to various environmental actions were the starting point for experimental research whose results will be presented in this article. Thus, in conjunction with these modern approaches, an analysis will be presented on the experimental results obtained in research on freeze/thaw resistance to different types of cements, carried out in collaboration with the laboratory of the Reinforced Concrete Structures Department, Technical University of Civil Engineering Bucharest and proposals for classification in different classes of freeze/thaw resistance.

The paper discusses means of testing the freeze-thaw resistance of concrete, which is part of an existing structure. Practically all standards and regulations dealing with freeze-thaw resistance describe tests that require cast prism-shaped specimens. This can make determining the freeze-thaw resistance of a concrete part of a structure rather difficult. The paper discusses the problem in detail, proposes solutions, and presents a real-world example of determining the freeze-thaw resistance of bridge abutments.

This paper aims to investigate the freeze-thaw resistance of cement-paste containing with different diameter and content of multiwalled carbon nanotubes (MWCNTs) in terms of mechanical properties and microstructure. Three groups of cement-paste with MWCNTs diameter of 10-20 nm, 20-40 nm and 40-60 nm were prepared by incorporating 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt% MWCNTs by cement weight. Experimental results showed that the addition of 0.1 wt% MWCNTs with diameters of 10–20 nm effectively improved the freeze-thaw resistance of cement-paste. In addition, microstructural analysis of these cement-paste specimens showed that MWCNTs addition increased the materials’ initial porosity, but a proper amount of MWCNTs decreased the porosity of cement-paste after freeze-thaw cycles and effectively improved the pore size distribution. MWCNTs 10–20 nm in diameter were found to be the optimal size for improving the microstructure of these MWCNTs cement-paste

The present paper deals with the long-term experimental study focusing on the properties of concrete mixtures with the addition of ceramic powder, which originate during the hollow brick production...

The present paper assesses the state of degradation from the action of the freeze-thaw phenomenon on the new cement mixes made with addition of granulated and ground blast furnace slag (GGBS) but also with partial replacement of the natural aggregates with different percentages of artificial aggregates from ungranulated and crushed blast furnace slag (ACBS).The purpose of this study is to evaluate the behavior of road concrete mixtures versus blends made with conventional materials for an extended period of repeated freeze-thaw cycles. Thus, from 100 freeze-thaw cycles, as is commonly practiced for road concrete, the test period was extended to up to 150 cycles and then up to 300 freeze-thaw cycles. Three blends were made with 15% addition of slag powder of less than 63 μm and 20%, 40%, 60% of artificial aggregates of 0/4mm that replaced the natural sand.The variation of the dynamic elastic modulus at 150 cycles and, respectively, at 300 freeze-thaw cycles was tested by the non-destructive ultrasonic methodon laboratory samples. It was thus noticed that in the mixture in which 15% added slag powder and 60% artificial aggregates were incorporated the durability performance was affected, especially at 300 freeze-thaw cycles. However, in the mixture with 15% added slag powder and 40% artificial aggregates the durability characteristics improved compared to the previous blend and in the mixture with 15% addition of slag powder and 20% artificial aggregates the results were much better than those obtained in blends made with conventional materials.

Cohesive soils are very often found in the soil subbase. In order to be a fully-fl edged building subbase, they must be improved. A popular way to improve is to stabilise with binders. In addition to common cement, mixtures of Portland clinker, ash, slag and additives, known as hydraulic road binders, are used. Standard binders allow for increased compressive strength, but do not provide the expected frost resistance that should protect the road structure from frost damage. In the paper the use of a hydrophobic additive of organic origin, produced from natural raw materials – vegetable and animal fats is proposed to reduce water absorption into the stabilised layer, providing improved compression strength and frost resistance of the layer. The addition of diamidoamine lactate to the soil–cement mixtures increased their compressive strength 3 to 8 times, for samples containing 7% binder and 2 to 2.5 times for samples containing 9%, in relation to standard binders.

Repairing concrete structures costs billions of dollars every year all around the globe. For overcoming durability concerns and creating enduring economical structures, chemical admixtures, as a unique solution, have recently attracted a lot of interest. As permeability of a concrete structure is considered to play a significant role in its durability, Permeability Reducing Admixtures (PRA) is one of the ideal solutions for protecting structures exposed to water and waterborne chemicals. Different products have been developed to protect concrete structures against water penetration, which, based on their chemistry, performance, and functionality, have been categorized into PRA. As it has previously been tested by authors and proven to be a promising solution, a hydrophilic Crystalline Waterproofing Admixtures (CWA) has been considered for this study. This paper aims to investigate how this product affects concrete’s overall freeze–thaw resistance, self-sealing, and corrosion resistance. Various testing methods have been utilized to examine the performance of CWA mixtures, including the linear polarization resistance, resonance frequency testing, half-cell potential, and self-sealing test. The reinforcement corrosion potential and rate measurements indicated superior performance for CWA-treated samples. After being exposed to 300 freeze–thaw cycles, concrete mixes containing CWA—even non-air-entrained ones—showed a Durability Factor (DF) of more than 80% with no signs of failure, while non-air-entrained control samples indicated the lowest DF (below 60%) but the greatest mass loss. The major causes are a reduction in solution permeability and lack of water availability in the concrete matrix—due to the presence of CWA crystals. Furthermore, evidence from the self-sealing test suggests that CWA-treated specimens can seal wider cracks and at a faster rate.

In cold regions, early deterioration of concretes due to freezing and thawing is a major concern. This study determined the freezing and thawing resistance of ultrahigh-performance concret...

This paper presents the testing of the durability of concrete where a part of cement was replaced with ground panel cathode ray tube glass (CRT) finer than 63 µm. The percentage of cement replaced with glass is 5%, 10%, 15%, 20%, and 35%, by mass. The highest percent share of mineral admixtures in CEM II (Portland-composiste cement) cement was chosen as the top limit of replacement of cement with glass. In terms of the concrete durability, the following tests are performed: freeze-thaw resistance, freeze-thaw resistance with de-icing salts-scaling, resistance to wear according to the Böhme test, sulfate attack resistance, and resistance to penetration of water under pressure. A compressive strength test is performed, and shrinkage of concrete is monitored. In order to determine the microstructure of concrete, SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) analyses were performed. The obtained research results indicate that the replacement of a part of cement with finely ground CRT glass up to 15% by mass has a positive effect on the compressive strength of concrete in terms of its increase without compromising the durability of concrete. The results obtained by experimental testing unequivocally show that concrete mixtures made with partial replacement (up to 15%) of cement with finely ground CRT glass have the same freeze-thaw resistance, resistance to freeze/thaw with de-icing salt, resistance to wear by abrasion, and resistance to sulfate attack as the reference concrete. In terms of environmental protection, the use of CRT glass as a component for making concrete is also very significant.

Use of recycled aggregate in concrete-mix provides many advantages for waste management; more efficient energy and natural resource use, ecological protection, and lower CO2 emissions. This study i...

A set of Class F fly ash-based geopolymer concrete with slag gradient, namely, GPC-10 (10% slag content), GPC-30 (30% slag content) and GPC-50 (50% slag content), was prepared to study its freeze-thaw resistance. GPC-10 was wrapped in aluminum foil and cured at 80 °C for 24 h to accelerate strength development. The others were cured under standard conditions (20 ± 2 °C, relative humidity ≥95%). Rapid freeze-thaw cycle testing was carried out according to ASTM C666 , and an ordinary Portland cement concrete (OPCC) sample was used as the control. The freeze-thaw resistance was evaluated by mass loss, relative dynamic elasticity modulus and compressive strength loss. In addition, the microstructure and mineralogy were characterized using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), energy dispersive X-ray spectrosocpy (EDS) and X-ray diffraction (XRD). The results show that GPC-10 is damaged after five freeze-thaw cycles, although high temperature curing improves its freeze-thaw resistance. GPC-30 is damaged in 50 freeze-thaw cycles, while GPC-50 can withstand 225 freeze-thaw cycles, which is comparable to the freeze-thaw resistance of the OPCC. Also, 125 freeze-thaw cycles marks an inflection point for the freeze-thaw resistance of GPC-50, which is verified by the SEM and MIP results. The effect of adding slag on the enhanced freeze-thaw resistance was analyzed by EDS and XRD.

The durability of concrete to freeze and thaw (F-T) cycles is one of the most important challenges of reinforced concrete structures in regions with cold climate. Thus, studying the effect of this ...

High-performance fiber reinforced cementitious composites from ettringite-based binders require much understanding of durability before its real-life applications in construction industry. A strain-hardening fiber reinforced ettringite-based composite from the hydration between ladle slag and gypsum with polypropylene (PP) fibers was the object in this study. To investigate the durability of the developed composite under aggressive conditions in cold regions (e.g., the Northern Europe), the material was subjected to a combined sodium sulfate-chloride solution along with freeze-thaw cycling process, which represented the marine environment of cold regions. The experimental study reports the vital role of PP fibers in control crack propagation and, hence, greatly enhanced the durability of the composite. In addition, the developed composite attained good mechanical performance with deflection-hardening behavior and multiple crack even after aging processes. Materials, aged in water, was mainly destructed by volume expansion from water uptake in structural pores, while those, cured in Na2SO4 NaCl solution, was mainly spoiled by volume increase from both physical and chemical attacks.

This research investigates the potential use of waste white cement by pass dust (WCBPD) in producing roller-compacted concrete (RCC). Fifteen RCC mixes were casted in which cement was partially rep...

The authors obtained fine grain concrete based on the mortars of additives-electrolytes undergone mechanic magnetic activation and characterized by improved compression and bending strength and enhanced freeze-thaw resistance. There was investigated the impact of mechanic magnetic activation (MMA) on mixing water when adding calcium chloride and sodium thiosulphate as well as on porosity of cement stone and specific features of phase formation in cement stone. It was stated by the authors that MMA facilitates formation of nucleation centers in activated water in the presence of additives-electrolytes, optimization of porous space as well as crystallization of calcium carbonate in the form of aragonite when lowering the content of Portlandite. The mechanism of joined influence of hydrodynamic and magnetic treatment of mixing water has been determined.

Externally bonding using epoxy is one of major applying method for FRP strengthening technology. The long-term performance of the epoxy/concrete interface has been proven to be a key for practical application of FRP strengthening, especially when the strengthened structures are exposed to severe environmental conditions. In this study, an experimental program has been carried out to examine the effect of freeze–thaw cycles (soaked in tap water and 5% sodium sulfate solution) on the deterioration of the epoxy/concrete interface through a novel wedge splitting test, which can directly measure the traction-separation law of the interface under mode I loading. The effect of silane treatment on the freeze–thaw resistance of the interface was also examined. A simplified tri-linear constitutive model of the epoxy/concrete interface was obtained according to the test results. Results showed that both the ultimate bond strength and the fracture energy decrease exponentially with the number of freeze–thaw cycles. Under mode I loading, the failure mode of the reference specimen is the tensile failure of the concrete. With the increase of freeze–thaw cycles, the failure mode gradually turns into adhesive failure along the epoxy/concrete interface. Testing results also confirm that the freeze–thaw resistance of the epoxy/concrete interface can be improved by application of silane coupling agent.

This paper describes a study of the effect of partial replacement of ordinary Portland cement (OPC) by various mineral additives in the screed mixtures. Ceramic powder, blast furnace slag and fly ash were gradually employed in increments of 12.5 wt.% up to 50 wt.% to replace OPC. The mixtures were designed to a constant consistency. The influence of mineral additives was evaluated in terms of the air content in the fresh mixtures, the compressive strength, the flexural strength and the freeze-thaw resistance and using non-destructive measurements after 28 and 90 days. The accompanied paste sampleswere analysed using thermogravimetry to monitor the hydration process by means of total bound water content. The decrease in the mechanical properties and the frost resistance of the mixtures with the mineral additives were recorded, because of the necessity for a larger addition of water. According to the valid standards for concrete screed related to the frost resistance, it could be concluded that maximal suitable cement replacement contents are 12.5, 37.5 and 50 wt.% for ceramic powder, fly ash and blast furnace slag, respectively. The freeze-thaw resistance of the studied materials was found to be strongly related to the content of CSH and CAH hydrates.

This paper investigates the preparation and assessment of mortar-phase change materials (PCM) systems to gain a full understanding of using the heat stored in PCMs to delay or prevent ice formation in concrete. Desirable PCMs and light weight aggregates (LWA), which act as carriers of the PCMs, were first selected based on their thermal and physical properties. LWAs containing PCMs were prepared and assessed for different combinations of materials. Cyclic freeze-thaw mass loss, latent heat attenuation, and FTIR tests were conducted to characterize the stabilities of the LWA-PCMs. The thermal performances of the mortars containing LWA-PCMs were investigated using a longitudinal guarded comparative calorimeter (LGCC) that was operated under quasi-steady state conditions during the cooling/heating process. The results confirmed that PCMs can be steadily absorbed in LWAs without chemical reactions or great losses in latent heat when the LWA-PCMs were coated in a certain way. Cement paste was recommended to coat the surface of the LWA-PCMs for better compatibility with the system than that of traditional coating materials. The ability of the PCM to delay or prevent ice formation in mortar was verified from the exothermic/endothermic events associated with the phase transformations of the pore solution and PCM. In the present study, when up to 50% vol. of the LWA was replaced as carriers of PCM, the heat released by the PCM was sufficiently high to inhibit ice formation.

Stone slate used for roofing is often considered as a key element of architectural heritage, especially in the French ‘‘Massif Central’’ region, where it contributes to the Mediterranean agropastoral cultural landscape of the “Causses and Cevennes” perimeter registered on the UNESCO World Heritage List. This material is subjected in service to severe and cycled climatic conditions (freeze-thaw) that may lead from mechanical damage to failure and thus compromise its use. In this paper, a damage assessment strategy of limestone roofing tiles samples during freeze-thaw cycles, based on the monitoring of their impulse vibration response, is proposed. Variations of the modal parameters such as resonant frequencies, damping ratios and mode shapes are analyzed through a 3D finite element model of each sample. This allows quantifying the loss of dynamic stiffness due to the ongoing damage and drawing comparisons between the studied materials in relation to their microstructural and mesostructural damages. Thus presence of pre-existing diagenetic features, such as stylolites (Ds in Nicholson classification), inside limestone tilestone with unimodal micropore, or with presence of high porosity volume, constitute weaknesses of the stone that can lead to damage.

This study evaluates the freeze-thaw performance of steel fibre reinforced rubberised concretes (SFRRuC) engineered for flexible concrete pavements. The effect of large volumes of fine and coarse rubber particles (i.e. 30% and 60% volumetric replacement of natural aggregates) is determined for concretes reinforced with 40 kg/m3 of a blend of manufactured steel fibres and recycled tyre steel fibres. The freeze-thaw performance is assessed through surface scaling, internal damage, residual compressive strength and flexural behaviour. The results show that SFRRuC are able to withstand 56 freeze-thaw cycles with acceptable scaling and without presenting internal damage or degradation in mechanical performance. This indicates that SFRRuC can perform well under extreme freeze-thaw conditions and can be used to construct long-lasting flexible pavements as a sustainable alternative to asphalt concretes.

This research is focused on the utilization of cable waste originating during the recycling of wires as a partial substitution of natural aggregate in cement screed. The main goal of the work performed was to find an optimal level of substitution in terms of freezing–thawing resistance, which is a significant aspect for such type of concrete mixtures. The studied artificial aggregate was gradually dosed in cement screed by 5% in a volume of up to 30% of substitution. The influence of the substitution was also evaluated in terms of compressive strength, flexural strength, bulk density determination, and the ultrasonic pulse method. Gradual substitution led to the reduction of the bulk density and studied mechanical properties due to the considerable air-entraining effect. The utilization of cable waste reduced the value of modulus of elasticity and modified deformation behavior of studied mixtures, which exhibited significant softening during the flexural test. Studied screed mixtures incorporating waste material exhibited slightly lower values of the coefficient of freeze-thaw resistance in comparison with the control mixture, however, the attained values comply with technical requirements.

The present study investigated the resistance of concrete blended with ground granulated blast furnace slag (GGBS) and ferronickel slag (FNS) to cycles of freeze and thaw. The replacement ratio of the binders was 0%, 50 wt% of GGBS and 30 wt% of GGBS + 20 wt% of FNS for O100, OG50 and OG30F20, respectively. Specimens consisted of cement paste and concrete kept at 0.45 water/binder ratio. After 28 days of curing, specimens were subjected to freeze and thaw cycles (300) for measuring the variation of strength, weight loss and fundamental transverse frequency. Simultaneously mercury intrusion porosimetry was performed to examine the pore structure modifications at 28 days. The hydration products for cement paste cured at each determined age were characterized by X-ray diffraction and the content of CH and CSH was obtained from thermogravimetric analysis (TGA). As a result, the ternary blended concrete specimens showed lower deterioration degree when subjected to the freeze and thaw cycles. This may be due to a latent hydraulic and/or pozzolanic reaction producing more CSH in the matrix, which in turn increases the volume of small pores. The increased content of C–S–H gel for OG30F20 was confirmed by TGA, accounting for 69.9%. However, the binder system consisting of ordinary Portland cement and GGBS did not exhibit higher resistance to the given deleterious environment, presumably due to a delayed hydration process.

In this paper, three freezing-thawing tests are designed to study the freeze-thaw resistance of stabilized sulfate type saline soil. The results show that different destructive modes and erosion extents are caused by different freeze-thaw conditions. The destructive effect from salt tends to be limited if there is no external water intrusion. When sufficient water is provided, ice expansion, dissolution recrystallization of salts, and ettringite growth during the thawing phase may take place. Soil water potential is used for analysis and explanation of the driving force and water migration in the stabilized soil. Pressure potential caused by the air sealed in the stabilized soil specimen leads to early water concentration in the outer parts of the specimen, and the surface layer is first eroded under the freeze-thaw cycles. A high percentage of soil stabilizer can improve the freeze-thaw resistance of stabilized soil, but a sufficiently long curing period plays a more important role. This study provides useful insights for improving the freeze-thaw resistance of solidified saline soil in road engineering.

The article is devoted to determining the patterns of improving the performance of concrete using hydro-remote ash-slag mix and polypropylene fiber. For this, a four-step methodology was developed for producing purified aluminosilicates from ash-slag mix. A set of experimental studies included the study of both raw materials and developed composites. The compressive strength, flexural strength, and freeze-thaw resistance were chosen as the target characteristics. The mechanism of the effect of purified aluminosilicates on the compaction of the composite structure was determined. At the same time, polypropylene fiber effectively inhibits the formation of cracks and they growth. The optimal composition is the replacement of cement with an ash-slag mix in an amount of 50% and in the presence of fiber. In this case, the compressive strength was increased by 19%, and the flexural strength by 122% compared with the reference composition. Thus, it was proved that both hydro-remote ash-slag mix and polypropylene fiber, and especially from combined use, make it possible to create effective fiber-reinforced concrete with excellent mechanical and durability characteristics.

The current building industry is a dominant contributor to related carbon dioxide emission, hence gradual reduction of this trend is the main issue of researchers worldwide. The utilization of traditional Portland cement is currently reduced due to its high energy consumption during the production. Hence, number of binding materials or cement supplementary materials are intensively studied to reduce negative impact of Portland production. The long-term research is focused on the development of new type of binder, which is produced from the fly ash and other waste materials originating from the combustion of the coal in the power plants. The significant moment of the production of this hydraulic binder in the mechanical activation by the grinding. This perspective binder material was used for the production of the sets of vibro-pressed pavement blocks to replace Portland cement in the core layer. The potential of the replacement was studied in terms of freezing-thawing test. The resistance was determined on the basis of residual splitting strength after prescribed number of cycles. Conducted research confirmed previous results, that full replacement lead to the significant loss of the durability performance, however it was declared that this new binder material could replace more than 50% of Portland cement.

This paper studies the effect of curing temperature on the early freezing-thawing resistance of HVFA concrete, and determines the early freezing-thawing resistance of HVFA concrete under different curing temperatures by testing the compressive strength, mass and ultrasonic wave velocity of the specimens. The results show that curing temperature has a certain influence on the early freezing-thawing resistance of HVFA concrete. The decrease rate of the compressive strength of HVFA concrete cured at 40℃ is the least, and the quality of HVFA concrete cured at different curing temperatures firstly increases and then decreases with the increase of the number of freezing-thawing cycles. According to the freeze-thaw damage value defined by wave velocity, curing temperature has a great influence on the freeze-thaw damage of HVFA concrete.

Concrete is the most commonly used construction material due to its various advantages, such as versatility, familiarity, strength and durability and it will continue to be in demand far into the future. However, with today’s sensitivity to the environmental protection, this material is facing unprecedented challenges due to its high greenhouse gas emission mainly during cement production. This paper investigates one of the promising cement replacement materials, alkali activated cement (AAC) concrete. Being produced mainly from byproduct materials and having a comparable structural performance to conventional concrete, AAC concrete has a potential to transform the construction industry. Mechanical properties such as compressive and flexural strength and the relationship between them are studied. Different source materials such as fly ash (FA), ground granulated blast furnace slag (GGBS), silica fume (SF) and Metakaolin (MK) are used. The effect of the source materials and the activator solutions on the concrete performance is studied. Furthermore, the freeze-thaw resistance of the concrete is studied. The results of the study showed that the behavior of AAC depends highly on the source material combinations as well as type used. The effect of the alkaline solution is also dependent on the source material used. Mixes with higher GGBS content in general showed the highest strength while mixes with MK showed the highest flexural strength. The results from the freeze-thaw test showed that proper design of AAC concrete with a lower water content is critical to achieve a good resistance.

Quartz sandstone (QS) is a mine waste, therefore, its use in construction allows for both reducing the cost of the concrete and contributing to the utilization of waste. The scientific originality of this study is the identification of models of the effect of QS aggregate on the physicomechanical, durability characteristics, and eco-safety of greener high-strength concrete. The study used an energy-efficient method of non-thermal effects of electromagnetic pulses on the destruction mechanisms of quartz-containing raw materials. The characteristics of quartzite sandstone aggregates, including the natural activity of radionuclides, were comprehensively studied. The features of concrete hardening, including the formation of an interfacial transition zone between the aggregate and the cement matrix, were studied, taking into account the chemical and morphological features of quartzite sandstone. In addition, the microstructural and morphological properties of concrete were determined after a 28 day curing. In this study, the behaviors of the concrete with QS aggregate were investigated, bearing in mind the provisions of geomimetics science on the affinity of structures. The results obtained showed that the QS aggregate had the activity of natural radionuclides 3&ndash, 4 times lower compared to traditional aggregates. Efficient greener concrete with a 46.3 MPa compressive strength, water permeability grade W14, and freeze&ndash, thaw resistance of 300 cycles were also obtained, demonstrating that the performance of this greener concrete was comparable to that of traditional concrete with more expensive granite or gabbro diabase aggregates.

This investigation studies the effects of hot water and hot air curing on the strength development, transport properties, and freeze-thaw resistance of mortars incorporating low-heat blast furnace slag cement and nanosilica (NS). Mortar samples were prepared and stored in ambient conditions for 24 h. After demolding, mortar samples were subjected to two different hot curing methods: Hot water and hot air curing (40 &deg, C and 60 &deg, C) for 24 h. For comparison purposes, mortar reference mixes were prepared and cured in water and air at ambient conditions. Strength development (from 1 to 180 days), capillary water porosity, water sorptivity, and freeze-thaw resistance were tested after 180 days of curing. The experimental results showed that both curing regimes accelerate the strength development of mortars, especially in the first seven days of hydration. The highest early strengths were reported for mortars subjected to a temperature of 60 &deg, C, followed by those cured at 40 &deg, C. The hot water curing regime was found to be more suitable, as a result of more stable strength development. Similar findings were observed in regard to durability-related properties. It is worth noting that thermal curing can more efficiently increase strength in the presence of nanosilica, suggesting that NS is more effective in enhancing strength under thermal curing.

In this study, blast furnace slag geopolymer mortars were prepared in prism molds with the size of 4 x 4 x 16 cm by alkali activating powdered sodium meta silicate (Na2SiO3). The mortar mixtures prepared to contain sodium in different proportions were cured with 3 different curing methods, and 300 cycles of freeze-thaw were applied, and strength and weight losses were examined. Control samples prepared with PC were also exposed to freeze-thaw cycles and the results were compared with each other. It was observed that 8% sodium added geopolymer mortars significantly preserved their compressive strength and weight. Especially, the compressive strength of the samples produced with 8% sodium and exposed to freeze-thaw cycle after 28 days of air curing increased by around 32%.

The aim of this study was to present the problem of durability of structural lightweight concrete made of a sintered fly ash aggregate. The issue of durability was researched for 12 concrete series in terms of their water absorption, water permeability, and freeze-thaw resistance. Additionally, the microstructure of several concretes was analyzed with a scanning electron microscope (SEM). In the durability research, the influences of the following parameters were taken into consideration: The initial moisture content of sintered fly ash (mc = 0, 17&ndash, 18, and 24&ndash, 25%), the aggregate grading (4/8 and 6/12 mm), and the water-cement ratio (w/c = 0.55 and 0.37). As a result of various compositions, the concretes revealed different properties. The density ranged from 1470 to 1920 kg/m3, and the corresponding strength ranged from 25.0 to 83.5 MPa. The durability research results of tested lightweight concretes showed that, despite considerably higher water absorption, a comparable water permeability and comparable or better freeze-thaw resistance in relation to normal-weight concrete may be present. Nevertheless, the fundamental requirement of lightweight concrete to achieve good durability requires the aggregate&rsquo, s initial moisture content to be limited and a sufficiently tight cement matrix to be selected. The volume share of the cement matrix and aggregate, the cement content, and even the concrete strength are of secondary importance.

This study aims to study the freeze&ndash, thaw (F&ndash, T) resistance of asphalt mixture incorporating styrene&ndash, butadiene&ndash, styrene (SBS) polymer and basalt fiber by using the established complex master curves of the generalized Sigmoidal model. Asphalt mixture samples incorporating styrene&ndash, styrene (SBS) polymer and basalt fiber were manufactured following the Superpave gyratory compaction (SGC) method and coring as well as sawing. After 0&ndash, 21 F&ndash, T cycles processing, a complex modulus test asphalt mixture specimen was performed to evaluate the influence of the F&ndash, T cycle. Besides, according to the time&ndash, temperature superposition principle, the master curves of a complex modulus were constructed to reflect the dynamic mechanical response in an extended range of reduced frequency at an arbitrary temperature. The results indicated that the elastic and viscous portions of asphalt mixture incorporating SBS and basalt fiber have decreased overall. It could be observed from the dynamic modulus ratio that the dynamic modulus ratios of specimens were more affected by the F&ndash, T cycle at low frequency or high temperature. Thus, in the process of asphalt pavement design and maintenance, attention should be paid to seasonal frozen asphalt pavement under low frequency and high temperature.

This paper introduces the performance of a new air entraining agent (MY-1), and studies the performance of its air entraining concrete by comparing it with rosin air entraining agent (MY-2) and alkylbenzene sulfonate (MY-3), such as workability, bleeding rate, strength loss and frost resistance of fresh concrete. The results show that MY-1 air entraining agent can obviously improve the workability of concrete and reduce the bleeding rate of concrete; when the air content is 5.1%, the strength loss is 10.65%, and the relative dynamic modulus after 300 freeze-thaw cycles is 70.01%. The performance of MY-1 air entrained concrete is better than MY-2 and my-3 air entrained concrete in many aspects.

Ants have strict requirements on the building materials of the nest, such as the size, weight, luster and color of soil particles. The soil of underground ant nests is composed of clay particles cemented together to form a hard brick-like material. The ant nest powder shows pozzolanic activity after calcination, which can meet the requirements for active admixture of concrete. Under the standard curing condition, the influence of calcined ant nest clay powder (CANCP) on the durability of concrete is evaluated by chloride penetration resistance, carbonization resistance and freeze&ndash, thaw resistance, and the influence of the powder content is investigated. The results show that when the content of CANCP is less than 10%, the chloride penetration resistance of concrete increases with content of CANCP. In the early stage of carbonation, the greater the content of CANCP, the higher the carbonization rate of concrete. In the middle and later stage of carbonation, the carbonation rate of CANCP concrete is significantly lower than that in the early stage, and the carbonation depth is linearly related to the carbonation time. When the content of CANCP is less than 20%, the freeze&ndash, thaw resistance of CANCP concrete is better than that of the reference concrete.

The reuse of rubber in concrete results in two major opposing effects: an enhancement in durability and a reduction in mechanical strength. In order to strengthen the mechanical properties of rubber concrete, steel fibers were added in this research. The compressive strength, the four-point bending strength, the mass loss rate, and the relative dynamic elastic modulus of steel fiber reinforced rubber concrete, subjected to cyclic freezing and thawing, were tested. The effects of the content of steel fibers on the freeze&ndash, thaw resistance are discussed. The microstructure damage was captured and analyzed by Industrial Computed Tomography (ICT) scanning. Results show that the addition of 2.0% steel fibers can increase the compressive strength of rubber concrete by 26.6% if there is no freeze&ndash, thaw effect, but the strengthening effect disappears when subjected to cyclic freeze&ndash, thaw. The enhancement of steel fibers on the four-point bending strength is effective under cyclic freeze&ndash, thaw. The effect of steel fibers is positive on the mass loss rate but negative on the relative dynamic elastic modulus.

The RILEM technical committee TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ conducted a round robin testing programme to determine the validity of various durability testing methods, originally developed for Portland cement based-concretes, for the assessment of the durability of alkali-activated concretes. The outcomes of the round robin tests evaluating sulfate resistance, alkali-silica reaction (ASR) and freeze–thaw resistance are presented in this contribution. Five different alkali-activated concretes, based on ground granulated blast furnace slag, fly ash, or metakaolin were investigated. The extent of sulfate damage to concretes based on slag or fly ash seems to be limited when exposed to an Na2SO4 solution. The mixture based on metakaolin showed an excessive, very early expansion, followed by a dimensionally stable period, which cannot be explained at present. In the slag-based concretes, MgSO4 caused more expansion and visual damage than Na2SO4; however, the expansion limits defined in the respective standards were not exceeded. Both the ASTM C1293 and RILEM AAR-3.1 test methods for the determination of ASR expansion appear to give essentially reliable identification of expansion caused by highly reactive aggregates. Alkali-activated materials in combination with an unreactive or potentially expansive aggregate were in no case seen to cause larger expansions; only the aggregates of known very high reactivity were seen to be problematic. The results of freeze–thaw testing (with/without deicing salts) of alkali-activated concretes suggest an important influence of the curing conditions and experimental conditions on the test outcomes, which need to be understood before the tests can be reliably applied and interpreted.