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In order to further enhance the erosion resistance of cement concrete pavement materials, this study constructed an apparent rough hydrophobic structure layer by spraying a micro-nano substrate coating on the surface layer of the cement concrete pavement. This was followed by a secondary spray of a hydroxy-silicone oil-modified epoxy resin and a low surface energy-modified substance paste, which combine to form a superhydrophobic coating. The hydrophobic mechanism of the coating was then analysed. Firstly, the effects of different types and ratios of micro-nano substrates on the apparent morphology and hydrophobic performance of the rough structure layer were explored through contact angle testing and scanning electron microscopy (SEM). Subsequently, Fourier transform infrared spectroscopy and permeation gel chromatography were employed to ascertain the optimal modification ratio, temperature, and reaction mechanism of hydroxy-silicone oil with E51 type epoxy resin. Additionally, the mechanical properties of the modified epoxy resin-low surface energy-modified substance paste were evaluated through tensile tests. Finally, the erosion resistance of the superhydrophobic coating was tested under a range of conditions, including acidic, alkaline, de-icer, UV ageing, freeze-thaw cycles and wet wheel wear. The results demonstrate that relying solely on the rough structure of the concrete surface makes it challenging to achieve superhydrophobic performance. A rough structure layer constructed with diamond micropowder and hydrophobic nano-silica is less prone to cracking and can form more "air chamber" structures on the surface, with better wear resistance and hydrophobic performance. The ring-opening reaction products that occur during the preparation of modified epoxy resin will severely affect its mechanical strength after curing. Controlling the reaction temperature and reactant ratio can effectively push the modification reaction of epoxy resin through dehydration condensation, which produces more grafted polymer. It is noteworthy that the grafted polymer content is positively correlated with the hydrophobicity of the modified epoxy resin. The superhydrophobic coating exhibited enhanced erosion resistance (based on hydrochloric acid), UV ageing resistance, abrasion resistance, and freeze-thaw damage resistance to de-icers by 19.41%, 18.36%, 43.17% and 87.47%, respectively, in comparison to the conventional silane-based surface treatment. [ABSTRACT FROM AUTHOR]

To investigate the mechanical properties of cement concrete incorporating waste rubber powder, the response surface methodology was employed. The Box–Behnken central composite design was applied to analyze the three primary factors influencing the road performance of cement concrete containing waste rubber powder: the water–cement ratio, sand ratio, and waste rubber powder content. The study determined the impact of these factors on the flexural strength of waste rubber powder cement concrete at both 7 and 28 days. Additionally, the effects of the water–cement ratio, sand ratio, and waste rubber powder content on the performance of cement concrete were analyzed. To investigate the impact of waste rubber powder on cement concrete, various mechanical property tests were conducted, including compressive, flexural, dynamic elastic modulus, and impact performance tests. Furthermore, the study explored the influence of waste rubber powder on the noise reduction capacity of cement concrete using both the rubber ball impact method and ultrasonic method. Lastly, the durability of cement concrete with added rubber powder was assessed through shrinkage tests, frost resistance tests, and chloride ion penetration tests. [ABSTRACT FROM AUTHOR]

Surface coatings such as hydrophobic and transparent coatings were applied to cement concrete surfaces using Polydimethylsiloxane (PDMS) coatings, which have nanometer-sized particles. The degree of contact between the liquid and the coated surface reveals the surface’s ability to repel water, commonly referred to as hydrophobicity. By depositing silicon coating on the surface, we successfully achieved superhydrophobicity on cement concrete, providing excellent resistance against water damage. We are striving to replicate the natural superhydrophobic properties found in nature to create artificial surfaces with similar characteristics. In this study, we experimented to develop and evaluate superhydrophobic coatings on cement concrete. The application of PDMS on the cement concrete yielded fascinating results, with the typical contact angle of the coated layer measuring 178 degrees. We utilized ImageJ software to analyze the results. This innovative approach holds great promise for enhancing water repellency in the field of construction. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polycarboxylic superplasticizers (PCEs) exhibit numerous advantages as concrete additives, effectively improving the stability and strength of concrete. However, competitive adsorption of PCEs occurs in the presence of clay, which may affect the cement dispersion and water-reducing performance. Extensive research has been conducted on the physical and mechanical properties of PCEs; however, the effect of the diverse structures of PCEs on the competitive adsorption on clay and cement hydration products has been rarely studied. This study employs Ca-montmorillonite (CaMMT) as a clay representative, by constructing adsorption models of PCEs on CaMMT and cement hydration products. A comparison of the adsorption energies considering different side-chain lengths of PCEs is included. Typically, the adsorption energy on CaMMT is lower than that on hydration products, leading PCEs to preferentially adsorb on the clay, thereby reducing its effective dosage in the cement particles. The challenge of PCE adsorption on CaMMT increases with the polymerization degree, and methylallyl polyoxyethylene ether (HPEG) exhibits lower adsorption energies on CaMMT. The density of states (DOS) analysis indicated the highest peak values of allyl polyethylene ether (APEG) as well as the peak area at n (polymerization degree) = 1. The total number of transferred electrons for APEG was 0.648, surpassing those of other PCEs. The interaction mechanism of PCEs with clay and hydration products is further elucidated through electronic gain/loss analysis, also providing a basis for the theoretical analysis on how to reduce the adsorption of PCEs on clay and the structural design of mud-resistant PCEs. [ABSTRACT FROM AUTHOR]

Micro-cracks inevitably form in cement concrete structures, presenting substantial risks to safety, service life, and eco-efficiency. Developing high-intrinsic self-healing concrete offers a promising approach to promptly alleviate issues caused by microcracks. These issues include rapid matrix degradation and frequent maintenance requirements. This paper reviews recent advancements in autogenous self-healing concrete technologies. It discusses their classification, efficiency, and mechanisms based on concrete component categorisation, normalisation methods, and statistical analyses. Results indicate that intrinsic self-healing relies heavily on the physical and chemical properties of the concrete, external water, and crack dimensions. Several methods for adjusting concrete component parameters, types, and proportions enhance self-healing capability. In addition, minimising crack width proves beneficial. Enhancement mechanisms of each technology demonstrate significant diversity and complexity due to the intricate self-healing process. They primarily fall into three categories: mechanical mechanisms (microparticle accumulation, fibre bridging), physical mechanisms (swelling, ion adsorption, matrix porosity, roughness, crack width), and chemical mechanisms (improved hydration reaction, expansion product generation, precipitation reaction mechanisms, complexation-precipitation and chelation reactions). [ABSTRACT FROM AUTHOR]

Corrosion in reinforced concrete (RC) structures is a typical occurrence, particularly in coastal locations. Corrosion occurs when steel reinforcement within concrete is exposed to environmental variables such as moisture, oxygen, and chloride ions, resulting in a chemical reaction that deteriorates the steel and degrades the concrete structure's overall function. In order to create effective mitigation techniques, it is critical to evaluate the impact of corrosion on various types of concrete. Chloride ions, often present in marine environments penetrate the concrete cover and reach the steel reinforcement, through pores. The water-cement ratio is a critical factor in concrete mix design. Excess water in the mix can result in the formation of larger and interconnected pores, during the hydration process. Further, improper curing conditions, such as insufficient moisture during the initial stages of hydration, can cause incomplete hydration and the formation of pores. Therefore use of high dense and highly alkaline concrete such as geopolymer concrete (which does not require water curing), can be employed to reduce the impact of corrosion. In the present study an attempt was created to examine the rate of corrosion resistance in three different concrete types: conventional cement concrete (CC), self-compacting concrete (SCC), and geopolymer concrete (GPC). To induce corrosion in the RC (RC) beams, an accelerated corrosion test setup was employed. The main objective of the study is to examine and compare the corrosion resistance of the RC beams by altering the concrete type, which were then exposed to accelerated corrosion to replicate the consequences of long-term exposure to corrosive environments. From the experimental studies it was found that the CC specimens possess a loss (load carrying capacity) of 31.28%, the SCC and GPC specimens possess a loss of 30.08% and 24.95%, respectively. This shows that GPC has higher resistance to salt solution when compared to SCC and CC specimens. Further all the three specimens show similar ductility index (DI), which was found to be in the range between 2.3 and 2.38 with a marginal variation of ± 0.1. GPC shows a 27.41% reduction in carbon emission compared to CC. On the other hand, SCC demonstrates a 12.30% reduction in carbon emission compared to CC. The investigation revealed that the total energy demand for producing 1 m3 of conventional concrete was measured to be 1.88 gigajoules (GJ/m3). On the other hand, the energy demand for the same volume of self-compacting concrete was slightly lower, specifically 1.78 GJ/m3.

With the development of the technical trend, concrete using waste alternate material instead of sand material found economic potential for good structural behaviour. Besides, the susceptible crack, low strength-to-weight ratio, and low compressive strength are the reasons for shrinkage. Due to this reason, the investigation aims to limit the shrinkage under live load and increase the compression and flexural strength by the introduction of coconut waste chopped fiber (wCF), waste fly ash (wFA), and carbon nanotube powder (CNT) blended with conventional Portland paste. The developed concrete consists of 5 wt% wCF, 10 wt% wFA, and 0, 5, 10, and 15 wt% of CNT and is subjected to X-ray diffraction analysis, bulk density, compression and flexural strength, and water absorption studies. The X-ray diffraction pattern revealed the wCF, wFA, CNT, and matrix compositions. The concrete developed with 5 wt% wCF, 10 wt% wFA, and 15 wt% CNT cured within 28 days recorded maximum behaviour of compression strength (47 ± 1.8 MPa), flexural strength (4.9 ± 0.19 MPa), and water absorption of (2.8 ± 0.05 %).

This investigation delineates the enhancement of fly ash (FA) properties through mechanical treatments for sustainable construction applications and reducing carbon dioxide (CO2) emissions. FA, a byproduct of coal combustion in power generation, inherently exhibits limited pozzolanic activity. This research evaluates the impact of particle size reduction via dry and wet milling treatments on FA's pozzolanic behavior. The study's comparative analysis involves three FA variants: untreated raw material, dry-milled, and wet-milled FA. Extensive characterization encompassed chemical composition, physical properties, and microstructural features. Results demonstrate a marked improvement in pozzolanic activity in milled FAs, with wet milling yielding superior outcomes in particle size reduction (98% diminution compared to raw FA) and pozzolanic reactivity. The comparative assessment underscores wet milling's efficacy over dry milling and untreated FA in enhancing FA's performance as a sustainable construction material. In light of these findings, the study advocates for continued exploration of FA treatments, aiming to optimize their utility in eco-friendly construction practices.

In order to further enhance the erosion resistance of cement concrete pavement materials, this study constructed an apparent rough hydrophobic structure layer by spraying a micro-nano substrate coating on the surface layer of the cement concrete pavement. This was followed by a secondary spray of a hydroxy-silicone oil-modified epoxy resin and a low surface energy-modified substance paste, which combine to form a superhydrophobic coating. The hydrophobic mechanism of the coating was then analysed. Firstly, the effects of different types and ratios of micro-nano substrates on the apparent morphology and hydrophobic performance of the rough structure layer were explored through contact angle testing and scanning electron microscopy (SEM). Subsequently, Fourier transform infrared spectroscopy and permeation gel chromatography were employed to ascertain the optimal modification ratio, temperature, and reaction mechanism of hydroxy-silicone oil with E51 type epoxy resin. Additionally, the mechanical properties of the modified epoxy resin-low surface energy-modified substance paste were evaluated through tensile tests. Finally, the erosion resistance of the superhydrophobic coating was tested under a range of conditions, including acidic, alkaline, de-icer, UV ageing, freeze-thaw cycles and wet wheel wear. The results demonstrate that relying solely on the rough structure of the concrete surface makes it challenging to achieve superhydrophobic performance. A rough structure layer constructed with diamond micropowder and hydrophobic nano-silica is less prone to cracking and can form more “air chamber” structures on the surface, with better wear resistance and hydrophobic performance. The ring-opening reaction products that occur during the preparation of modified epoxy resin will severely affect its mechanical strength after curing. Controlling the reaction temperature and reactant ratio can effectively push the modification reaction of epoxy resin through dehydration condensation, which produces more grafted polymer. It is noteworthy that the grafted polymer content is positively correlated with the hydrophobicity of the modified epoxy resin. The superhydrophobic coating exhibited enhanced erosion resistance (based on hydrochloric acid), UV ageing resistance, abrasion resistance, and freeze-thaw damage resistance to de-icers by 19.41%, 18.36%, 43.17% and 87.47%, respectively, in comparison to the conventional silane-based surface treatment.

Concrete, as an engineering material with extremely wide applications, is widely used in various infrastructure projects such as bridges, highways, and large buildings. However, structures such as highways and bridges often need to be situated in variable and harsh service environments for long periods. They not only face cyclic reciprocating vehicle loads but also have to contend with the effects of temperature cycling. Therefore, studying the impact and mechanism of temperature differential cycling on the compressive strength and fatigue life of cement concrete has certain theoretical significance and practical value. This study employed a comprehensive experimental design to investigate cement concrete specimens subjected to typical temperature variations (20–60 °C) and different numbers of temperature differential cycling (0, 60, 120, 180, 240, 300). Axial compressive strength tests, ultrasonic tests, and compressive fatigue tests were conducted. The axial compressive strength test measured the compressive strength of the cement concrete. It was found that with an increase in the number of temperature differential cycling, the compressive strength exhibited a trend of an initial increase followed by a decrease: at 60 cycles, the strength increased by 10.8%, gradually declined; returned to near-initial strength at 120 cycles, and continued decreasing, reaching a decline of 19.4% at 300 cycles. The ultrasonic test measured the ultrasound velocity of the concrete specimens after different temperature differential cycling. It revealed a decreasing trend in ultrasound velocity with an increase in times of temperature differential cycling, showing a strong linear relationship between the ultrasound velocity loss and strength loss, confirming the correlation between the degree of concrete strength degradation and internal damage. The compressive fatigue test analyzed the fatigue life variation in cement concrete under different times of temperature differential cycling and stress levels, showing good adherence to the Weibull distribution pattern. Based on the approximation assumptions of log-normal distribution and the Weibull distribution, the Weibull distribution parameters for the compressive fatigue life of cement concrete under temperature differential cycling were obtained. [ABSTRACT FROM AUTHOR]

In order to save and improve the utilisation of magnetite meanwhile rise the road microwave deicing efficiency, double-layer cement concrete specimens with different magnetite contents were designed. The heating efficiency and heat distribution of the surface and heat conduction process and electromagnetic loss of internal of the double-layer magnetite cement concrete (DLMCC) were studied. In addition, the relative absorptivity based on energy conservation was used to evaluate the energy utilisation efficiency. The results show that the double-layer structure could save 80% of magnetite and make utilisation of magnetite reach 93.39%. The surface temperature rise rate of DLMCC was improved greatly while was obtained through a low surface temperature/magnetite ratio. The optimum heat distribution of DLMCC was in the range of −2.24°C to 1.66°C of surface temperature. The influence regions of internal heat on the surface temperature were constant. The maximum electromagnetic loss of DLMCC within 10 mm of the surface was 27.43%, and the maximum energy utilisation efficiency of DLMCC increased by 14.35%. [ABSTRACT FROM AUTHOR]

Recent advances in the application of superabsorbent polymers (SAP) for frost resistance in internal curing of concrete, both domestically and internationally, are comprehensively reviewed・ The current status of SAP types and their applications in concrete are presented, along with discussions on SAP synthesis methods, water absorption and release principles, and design strategies for add让ional water intake・ The influence of SAP particle size, dosage, synthesis methods, and additional water intake on the frost resistance of concrete is thoroughly explored ・ Lastly, key research points in the field of SAP internal curing of concrete are summarized, while also envisioning the future research direction of SAP internal curing in cold and high・altitude regions・ This includes the development of SAP materials suitable for specific environments, establishment of additional water intake models in different conditions, and incorporation of self-healing bio-colonies ・ [ABSTRACT FROM AUTHOR]

Corrosion of rebars and metal inclusions has always been a concern for the construction industries looking for bulk utilization of the industrial waste as alternative of natural construction material. In the present study the performance of cement mortar incorporating 100% coalmine overburden (OB) as fine aggregate, and cement concrete incorporating 100% OB as fine and coarse aggregate has been assessed through the carbonation and rapid chloride penetration tests. Comprehensive testing was performed to characterize the OB owing to its chemical, physical, and mechanical properties, to conform its suitability as a replacement to natural aggregate. Characterization of OB based on strength, morphology, mineralogy, and durability, indicate that the waste rock can be a good replacement to natural aggregate in cement mortar and concrete. It was observed that the 7 days compressive strength of 15 MPa was maximum at different (0.6 to 0.8) water cement ratios depending upon chemical composition, and the specific surface (16 m2/g and 20 m2/g) for OBM1 and OBM2.The carbonation depth increased from 0 to 0.35 cm for OBM1 and 0 to 0.5 cm for river sand. The total charge was found to be 144 C, 347 C, and 13 C for different OBs at a nominal mix of 1:2:4, and a w/c of 0.6 during rapid chloride penetration. The performance of mortar and concrete prepared using OB as 100% replacement of aggregate under corrosion testing were found to be comparable to that of river sand. [ABSTRACT FROM AUTHOR]

To investigate the mechanical properties of cement concrete incorporating waste rubber powder, the response surface methodology was employed. The Box–Behnken central composite design was applied to analyze the three primary factors influencing the road performance of cement concrete containing waste rubber powder: the water–cement ratio, sand ratio, and waste rubber powder content. The study determined the impact of these factors on the flexural strength of waste rubber powder cement concrete at both 7 and 28 days. Additionally, the effects of the water–cement ratio, sand ratio, and waste rubber powder content on the performance of cement concrete were analyzed. To investigate the impact of waste rubber powder on cement concrete, various mechanical property tests were conducted, including compressive, flexural, dynamic elastic modulus, and impact performance tests. Furthermore, the study explored the influence of waste rubber powder on the noise reduction capacity of cement concrete using both the rubber ball impact method and ultrasonic method. Lastly, the durability of cement concrete with added rubber powder was assessed through shrinkage tests, frost resistance tests, and chloride ion penetration tests.

Traditional cement concrete has the disadvantages of low tensile strength, poor toughness, and rapid development of cracks while cracking, which causes a significantly negative influence on the safety and durability of concrete road pavement. This paper presents a state-of-the-art review of toughness improvement mechanisms and evaluation methods of cement concrete for road pavement. The review indicates that (i) The performance of concrete material depends on its material composition and internal structure. Aggregate size, cement properties and admixtures are the main factors of concrete toughness. (ii) The incorporation of rubber or fiber in pavement concrete improves the toughness of concrete materials. However, these additions must be maintained within a reasonable range. The amount of rubber and fiber are encouraged not more than 30% of the volume of fine aggregate and 2% of the volume of concrete, respectively. (iii) The toughness of pavement concrete material includes the toughness regarding bending, impact and fracture. The toughness of cement concrete for highway and municipal pavement is generally evaluated by bending and fracture toughness, while the toughness of airfield pavement concrete is more focused on impact toughness. (iv) The toughening measures of cement concrete for road pavement are mainly mixed with rubber or fiber, while these two materials have their defects, and the application of high-toughness cement concrete in the actual road still faces many challenges. For example, the synergistic effect of rubber and fiber, the development and application of new flexible admixtures, and the formulation of the toughness index of pavement cement concrete materials need further research.

The disposal of hazardous waste materials in landfills and open areas creates a severe impact on the environment. Silica Fume (SF), a by-product from the ferrosilicon and silicon industry, is generated in high quantities. Recent studies have highlighted the advantages of reusing SF to produce high-strength concrete (HSC) and ultra-high-performance concrete (UHPC) instead of discarding it. This paper herein reviews the current research on SF in concrete and discusses the physical and chemical properties, mechanical properties, durability, and microstructure. Depending on the concentration of the SF, flexural, tensile, and compressive strength was positively influenced. Also, SF improved the pore size to increase drying shrinkage through the pozzolanic reaction. A few studies showed the disadvantages of SF exhibiting the negative impact on workability and shrinkage of concrete. The influence of SF on cement hydration products should be analyzed from the microstructure perspective.

This study introduces a novel methodology for optimizing the distribution of aggregate particles in concrete. Utilizing locally available materials like gravel and waste rock is explored as a sustainable alternative to conventional materials like mountain rock and river sand, which are depleting. Determining the maximum bulk density involves an efficient process of gradually adding different particle sizes of gravel and waste rock to the mixture. The vibrational compaction of the container aids in identifying the optimally combined percentages of these aggregates. Besides, the study also addresses the issue of porosity in concrete. The response surface methodology is employed to optimize the mixture proportions for concrete, considering important factors such as workability, compressive strength, flexural strength, and elastic modulus. This response surface methodology allows for the development of mathematical models that aid in determining the optimal mix ratios. By exploiting the potential of gravel and waste rock, this study aims to procedure cement concrete containing gravels and waste rock (WR) with required compressive strength from 30 MPa to 35 MPa based on reasonable aggregate particle distribution in combination with response surface methodology (RSM) and minimize the disposal of non-biodegradable waste, thereby reducing the environmental pollution. Additionally, utilizing locally available materials helps to effectively use the region's resources for concrete production, promoting sustainability and reducing dependency on scarce resources. The proposed method presents a promising approach to optimizing aggregate distribution in concrete while considering the environmental and resource constraints specific to the Northwest region of Vietnam. [ABSTRACT FROM AUTHOR]

Copyright of Materiały Budowlane is the property of Wydawnictwo SIGMA-NOT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polycarboxylic superplasticizers (PCEs) exhibit numerous advantages as concrete additives, effectively improving the stability and strength of concrete. However, competitive adsorption of PCEs occurs in the presence of clay, which may affect the cement dispersion and water-reducing performance. Extensive research has been conducted on the physical and mechanical properties of PCEs; however, the effect of the diverse structures of PCEs on the competitive adsorption on clay and cement hydration products has been rarely studied. This study employs Ca-montmorillonite (CaMMT) as a clay representative, by constructing adsorption models of PCEs on CaMMT and cement hydration products. A comparison of the adsorption energies considering different side-chain lengths of PCEs is included. Typically, the adsorption energy on CaMMT is lower than that on hydration products, leading PCEs to preferentially adsorb on the clay, thereby reducing its effective dosage in the cement particles. The challenge of PCE adsorption on CaMMT increases with the polymerization degree, and methylallyl polyoxyethylene ether (HPEG) exhibits lower adsorption energies on CaMMT. The density of states (DOS) analysis indicated the highest peak values of allyl polyethylene ether (APEG) as well as the peak area at n (polymerization degree) = 1. The total number of transferred electrons for APEG was 0.648, surpassing those of other PCEs. The interaction mechanism of PCEs with clay and hydration products is further elucidated through electronic gain/loss analysis, also providing a basis for the theoretical analysis on how to reduce the adsorption of PCEs on clay and the structural design of mud-resistant PCEs.

Water has a significant impact on the dielectric constant of materials. As a multiphase composite material, the effect of water content must be taken into account when modeling the composite dielectric of cement concrete. Cement concrete traditionally has been thought of as a three-phase mixed material consisting of mortar, aggregate (limestone), and pores (air). Water was used as a constituent material of cement concrete in this paper, and its content was described in terms of water saturation. By abstracting the components of cement concrete into independent medium units and arranging them according to certain rules, the four-phase mixing model of cement concrete can be established. To investigate the effect of water, the dielectric constant of cement concrete was measured using a network analyzer at various water saturation levels. The experimental results show that water significantly can enhance the dielectric constant of cement concrete, and this effect is related to porosity: the higher the water saturation, the faster the dielectric constant increases. According to the established concrete four-phase mixed model, combined with the parallel plate capacitor theory, a composite dielectric model considering water saturation was developed which can improve the prediction accuracy under different water saturation conditions and provide a foundation for the application of ground-penetrating radar (GPR) in the quality inspection of cement concrete pavement. [ABSTRACT FROM AUTHOR]

The relevance of the study is conditioned by the importance of the final condition of the roadside environment after road maintenance using various structural materials. The purpose of this study is to determine the state of the road environment after repair works using various materials in the context of performing a comparative analysis of such a state and identifying key aspects that take place during repair work to restore the integrity of the roadway using certain construction materials. The leading approach is a combination of methods of system analysis of various aspects of road repair and construction using various structural materials, with an experimental and analytical study of the processes occurring in the roadside environment during works with various materials, with the aim to form the necessary scientific basis for comparing the findings. The study results clearly demonstrate the degree of dependence of the roadside environment after repair works on the use of specific materials, since the quality of the building materials used is crucial from the standpoint of further road safety and the state of the roadside environment after performing particular works. [ABSTRACT FROM AUTHOR]

Thermal conductivity is a fundamental material parameter involved in various infrastructure design guides around the world. This paper developed an innovative neural network (NN) aided homogenization approach for predicting the effective thermal conductivity of various composite construction materials. The 2-D meso-structures of dense graded asphalt mixture, porous asphalt mixture, and cement concrete were generated and divided into 2n × 2n square elements with specific thermal conductivity values. A two-layer feed-forward neural network with sigmoid hidden neurons and linear output neurons was built to predict the effective thermal conductivity of the 2 × 2 block. The Levenberg-Marquardt backpropagation algorithm was used to train the network. By repeatedly using the neural network, the effective thermal conductivities of 2-D meso-structures were calculated. The accuracy of the above NN aided homogenization approach was validated with experiment, and various factors affecting the effective thermal conductivity were analyzed. The analysis results show that the accuracy of the NN aided approach is acceptable with relative errors of 1.92~4.34% for the dense graded asphalt mixture, 1.10~6.85% for the porous asphalt mixture, and 1.13~3.14% for the cement concrete. The relative errors for all the materials are lower than 5% when the heterogeneous structures are divided into 512 × 512 elements. Ignoring the actual material meso-structures may lead to significant errors (134.01%) in predicting the effective thermal conductivity of materials with high heterogeneity such as porous asphalt mixture. While proper simplification is acceptable for dense construction composite materials. The effective thermal conductivity of composite cement-asphalt mixtures increases with higher saturation of grouted material. However, the improvement effect of the high-conductive cement paste on the composite cement-asphalt mixtures could be significantly reduced when the cement paste concentrates at the bottom of the mixture. Cracked aggregates and segregation of material components tend to decrease the effective thermal conductivity of construction materials. The NN aided homogenization approach presented in this paper is useful for selecting the effective thermal conductivity of construction materials. [ABSTRACT FROM AUTHOR]

Automotive paint sludge (PS) is the waste product generated in the painting process of vehicle bodies. Although automotive spray painting is an automated operation, its efficiency is still quite low, since approximately 40–50% of the employed paint does not reach the target and, after being mixed with the collecting water, becomes PS. PS is a very complex material that contains several organic and inorganic components, in addition to 90% water immediately after production. Italian automotive factories produce from 2.5 to 5.0 kg of PS per painted car. If that figure is related to the number of vehicles produced worldwide every year, in the order of 100 million, it determines an annual PS amount in the order of 200,000–500,000 t. Consequently, a proper final destination for PS must be found. The waste management hierarchy and the principles of the circular economy require that we privilege solutions that foresee the recovery of valuable products or energy. This paper first reviews the processes and the machines that have been recently developed to obtain an enhanced mechanical dewatering of PS. The pretreatment of PS dewatering is often crucial in order to obtain high efficiency in the subsequent recovery process. Afterwards, the paper presents and discusses the recovery options that have been proposed and tested, at different scales, by several authors in the last thirty years. The processes for PS management can be grouped as follows: (i) direct employment of physically/chemically treated PS in the production of primers and sealants; (ii) utilization of PS for the production of building materials, as supplementary components of cement concrete, mortar, or bituminous mixtures; (iii) extraction of valuable organic and inorganic products by using thermal processes (pyrolysis, gasification); (iv) biological processes for PS detoxification, metal recovery, and stabilization before landfilling. [ABSTRACT FROM AUTHOR]

Motivated by the multiple benefits of recycling plastic ingredients in cementitious materials, the present study focuses on the design of sustainable cement concrete incorporating recycled mixed plastic fine aggregate (MPFA) as a partial replacement of natural sand (NS). The MPFA produced in this work is composed of a combination of polymer types with similar concoctions to those observed in the postconsumer waste streams. This study approach is vastly different from past reported studies on the use of sorted, highly purified single-type recycled plastic aggregate in cement concrete. A multi-criteria decision-making technique, Best-Worst Method (BWM), was integrated with the Taguchi method to maximize the quality of MPFA concrete based on the Fuller–Thompson theory. More specifically, an L9 (34) Taguchi orthogonal array with four three-level design factors was adopted to optimize the fresh, durability, and mechanical properties of MPFA concrete. The results showed that MPFA concrete produced with 400 kg/m3 cement content, 0.43 water/cement ratio, 0.43 fine aggregate/total aggregate ratio, and 10 vol% MPFA content exhibited the highest quality. Findings from the present work also revealed that MPFA concrete produced with tailored particle size distribution of MPFA NS fine aggregate system achieved superior, if not comparable, qualities to those of conventional concrete. [ABSTRACT FROM AUTHOR]

Cracks and cavities belong to two basic forms of damage to the concrete structure, which may reduce the load-bearing capacity and tightness of the structure and lead to failures and catastrophes in construction structures. Excessive and uncontrolled cracking of the structural element may cause both corrosion and weakening of the adhesion of the reinforcement present in it. Moreover, cracking in the structure negatively affects its aesthetics and in extreme cases may cause discomfort to people staying in such a building. Therefore, the following article provides an in-depth review of issues related to the formation and development of damage and cracking in the structure of concrete composites. It focuses on the causes of crack initiation and characterizes their basic types. An overview of the most commonly used methods for detecting and analyzing the shape of microcracks and diagnosing the trajectory of their propagation is also presented. The types of cracks occurring in concrete composites can be divided according to eight specific criteria. In reinforced concrete elements, macrocracks depend on the type of prevailing loads, whereas microcracks are correlated with their specific case. The analyses conducted show that microcracks are usually rectilinear in shape in tensioned elements; in shear elements there are wing microcracks with straight wings; and torsional stresses cause changes in wing microcrack morphology in that the tips of the wings are twisted. It should be noted that the subject matter of microcracks and cracks in concrete and structures made of this material is important in many respects as it concerns, in a holistic approach, the durability of buildings, the safety of people staying in the buildings, and costs related to possible repairs to damaged structural elements. Therefore, this problem should be further investigated in the field of evaluation of the cracking and fracture processes, both in concrete composites and reinforced concrete structures. [ABSTRACT FROM AUTHOR]

The thermal properties of pavement layers made of concrete with varying bulk densities are a particularly interesting topic in the context of development road technologies. If a hybrid layer system is used as a starting point, with thin asphalt layers (from 1 cm to 4 cm) laid on top of a foam concrete layer, thermal properties begin to play a crucial role. The main research problem was to create a test method enabling the assessment of the influence of solar heating on the thermal parameters of the building material, especially cement concrete. For this reason, this paper is concerned specifically with the assessment of a new methodology for testing and calculating the value of the thermal diffusivity coefficient of samples made of concrete varying bulk densities. In this case, using the proprietary concept the authors built a solar simulator using a multi-source lighting system. The analysis of the results of laboratory tests and numerical analyses allowed the authors to observe that there is a strong correlation between the bulk density of samples heated and the thermal diffusivity parameter, which appears in the unidirectional heat transfer equation. The strength of this relationship has been expressed with the coefficient of determination and amounts to 99%. The calculated values of the coefficient of thermal diffusivity for samples made of foam concrete range from 0.16 × 10 − 6 m 2 s to 0.52 × 10 − 6 m 2 s and are lower (from 2.5 to 8 times) than the value determined for samples made of typical cement concrete. [ABSTRACT FROM AUTHOR]

Concrete, as an engineering material with extremely wide applications, is widely used in various infrastructure projects such as bridges, highways, and large buildings. However, structures such as highways and bridges often need to be situated in variable and harsh service environments for long periods. They not only face cyclic reciprocating vehicle loads but also have to contend with the effects of temperature cycling. Therefore, studying the impact and mechanism of temperature differential cycling on the compressive strength and fatigue life of cement concrete has certain theoretical significance and practical value. This study employed a comprehensive experimental design to investigate cement concrete specimens subjected to typical temperature variations (20–60 °C) and different numbers of temperature differential cycling (0, 60, 120, 180, 240, 300). Axial compressive strength tests, ultrasonic tests, and compressive fatigue tests were conducted. The axial compressive strength test measured the compressive strength of the cement concrete. It was found that with an increase in the number of temperature differential cycling, the compressive strength exhibited a trend of an initial increase followed by a decrease: at 60 cycles, the strength increased by 10.8%, gradually declined; returned to near-initial strength at 120 cycles, and continued decreasing, reaching a decline of 19.4% at 300 cycles. The ultrasonic test measured the ultrasound velocity of the concrete specimens after different temperature differential cycling. It revealed a decreasing trend in ultrasound velocity with an increase in times of temperature differential cycling, showing a strong linear relationship between the ultrasound velocity loss and strength loss, confirming the correlation between the degree of concrete strength degradation and internal damage. The compressive fatigue test analyzed the fatigue life variation in cement concrete under different times of temperature differential cycling and stress levels, showing good adherence to the Weibull distribution pattern. Based on the approximation assumptions of log-normal distribution and the Weibull distribution, the Weibull distribution parameters for the compressive fatigue life of cement concrete under temperature differential cycling were obtained.

Microwave deicing technology, as a new environmentally friendly deicing technology, can effectively solve the problem of the frequent icing of road surfaces in the winter, which affects the safety of traffic. To improve the efficiency of microwave deicing on cement concrete pavement, this study proposed the use of magnetite, iron sulfide slag, steel slag, lead–zinc slag, and graphite as microwave-absorbing materials, and conducted microwave deicing tests under the influence of five factors, namely the form of the pavement surface structure, the content of the microwave-absorbing material, microwave power, the shielding state, and dry and wet conditions. Layer by layer, we selected the combination of pavement surface structure, microwave-absorbing material content, microwave power, shielding state, and dry and wet conditions on the bottom surface of the concrete slab with the optimal deicing effect. The results showed that the 2 cm scattered microwave-absorbing surface concrete structure has the fastest heating rate; the higher the magnetite content and microwave power, the higher the deicing efficiency; the maximum heating rate can be increased by 17.6% when the shielding layer is set at the bottom of the cement concrete slab; and the heating rate of the microwave-absorbing concrete slab in the wet state is increased by 20.8% relative to the dry state. In summary, 7000 W of power, a magnetite content of 60 vol % in the scattered microwave-absorbing surface, a shielding layer set at the bottom surface, and wet conditions can greatly improve the efficiency of microwave deicing compared with the microwave ice melting effects of plain cement concrete and other microwave-absorbing materials mixed into the concrete. In addition, the temperature uniformity of the microwave-absorbing materials is essential to improve the deicing efficiency of microwave-absorbing concrete, so it is essential to explore it further. [ABSTRACT FROM AUTHOR]

The assessment of the texture of airfield pavements, in addition to assessing their roughness, is a component of the broader concept of anti-skid properties, which significantly affect the safety of air operations. The roughness of the pavement directly affects the adhesion of the aircraft tire to the pavement, and the texture additionally affects the effectiveness of dynamic drainage of water from the pavement. The current standard requirements in terms of roughness and texture of airfield pavements do not distinguish the technology used. In the paper, the authors focused on the analysis of the results in terms of the texture of airfield pavements and presented the resulting conclusions in relation to whether the technology of its implementation has an impact on the texture parameter. [ABSTRACT FROM AUTHOR]

The mixing water used for cement concrete has a significant effect on the physical properties of the material after hardening; however, other than the upper limit for the mixed impurities, not enough consideration has been given to the functions and characteristics of water at the molecular level. In this study, we investigated the effect of four different types of water (two spring-, mineral waters, tap water and distilled water) on the drying shrinkage of the hardened cement by comparing the material properties of the concrete specimens and analyzing the molecular structure of the water and cement mortar using aquaphotomics. The near infrared (NIR) spectra of waters used for mixing were acquired in the transmittance mode using a high-precision, high-accuracy benchtop spectrometer in the range of 400–2500 nm, with the 0.5 nm step. The NIR spectra of cement paste and mortar were measured in 6.2 nm increments in the wavelength range of 950 nm to 1650 nm using a portable spectrometer. The measurements of cement paste and mortar were performed on Day 0 (immediately after mixing, cement paste), 1 day, 3 days, 7 days, and 28 days after mixing (cement mortar). The spectral data were analyzed according to the aquaphotomics' multivariate analysis protocol, which involved exploration of raw and preprocessed spectra, exploratory analysis, discriminating analysis and aquagrams. The results of the aquaphotomics' analysis were interpreted together with the results of thermal and drying shrinkage measurements. Together, the findings clearly demonstrated that the thermal and drying shrinkage properties of the hardened cement material differed depending on the water used. Better mechanical properties were found to be a result of using mineral waters for cement mixing despite minute differences in the chemical content. In addition, the aquaphotomic characterization of the molecular structure of waters and cement mortar during the initial hydration reaction demonstrated the possibility to predict the characteristics of hardened cement at a very early stage. This provided the rationale to propose a novel evaluation method based on aquaphotomics for non-invasive evaluation and monitoring of cement mortar. [ABSTRACT FROM AUTHOR]

The possibility of using cement granulate, a product of processing old cement concrete and waste generated during the demolition of buildings and structures, has been studied in the construction, reconstruction and repair of highways. The use of recycled materials in the road industry is one of the sources of saving natural raw materials. In addition, the use of waste solves environmental problems through the disposal of old waste materials and structures. Having completed the study of cement granulate, the possibility of using it for the construction of foundations for road pavements, as well as a substitute for crushed stone in the manufacture of concrete slabs of prefabricated coverings, has been determined. In the first case of using cement granulate, the wedge method is effective. It has been experimentally confirmed that the remains of cement mortar on the surface of used crushed stone contribute to its better wedging, thereby creating a more durable base layer. In order to assess the possibility of using cement granulate as a substitute for crushed stone for the manufacture of prefabricated concrete slab, standard studies of this material were carried out, the composition of the cement concrete mixture was selected, and standard samples were manufactured and tested. The test results have shown that the use of cement granulate for such purposes is quite acceptable. In particular, the average strength of the samples in the tested batch turned out to be 45.13 MPa and the guaranteed strength was 35.13 MPa, which corresponds to the B35 class of concrete. These indicators demonstrate that the use of cement granulate may well be in demand in the construction and reconstruction of local roads. At present, as it is known, a program is being implemented to improve the transport and operational level of local roads, and this is about 70 thousand kilometers. And here, of course, a huge amount of road construction materials will be required.

To account for the random orientation of ellipsoidal inhomogeneities, the averaging process over two Euler angles has been widely used in existing micromechanics models. However, the interaction among various inhomogeneity orientations is often overlooked and may also affect the prediction of composite elastic modulus. In this work, to consider the interaction among randomly oriented aggregates and fibers in cement concrete, a micromechanics model, the orientation interaction model (OIM), is proposed. An orientation average model (OAM) is also proposed, and by comparing OIM and OAM predictions, the effect of inhomogeneity orientation interaction on the predicted elastic modulus is shown. In both models, geometries of coarse aggregates and fibers are approximated using ellipsoids with three different semiaxes and cylinders, respectively, and their orientations are described using three Euler angles. Compared with existing random orientation models using two Euler angles, the proposed models can capture the isotropy of composites with randomly oriented asymmetric ellipsoidal inhomogeneities. By comparing the predictions of OIM, OAM, composite sphere models and the Mori-Tanaka method with spherical inhomogeneities, it is found that with the increase of the stiffness contrast between the matrix and inhomogeneities, the effects of the inhomogeneity geometry and orientation interaction become more apparent. The model predictions agree well with the experimental data. By changing the value range of three Euler angles based on the inhomogeneity orientation distribution, both models are also suitable for transversely isotropic and anisotropic composites containing several types of inhomogeneities. • The proposed models apply to composites with asymmetric ellipsoidal inhomogeneities. • Every parameter in the proposed models has a physical meaning, and model calibration is not needed. • The proposed models apply to transversely isotropic and anisotropic composites with several types of inhomogeneities. [ABSTRACT FROM AUTHOR]

The concept of sustainability requires that waste-modified materials also demonstrate adequate sustainability. This paper examines the effect of modifying cement concrete with waste lime dust on the course of concrete carbonation. The waste dust comes from the dedusting of aggregate for use in HMA – Hot Mixture Asphalt. The aim of the study was to examine whether the partial replacement of sand with waste powder would have a negative effect on the potential durability of a reinforced concrete element made of this concrete. To determine the extent of carbonation, an experimental plan was prepared including the execution of concretes with varying levels of substitution and a variable water/cement ratio. In order to identify long term influence the test was performed as indicated in EN 12390-12, but with the test time extended to 560 days. The results obtained were statistically analysed and the predicted maximum extent of carbonation depending on the level of substitution and the water/cement ratio was determined. The analysis indicates that it is possible to substitute sand with waste limestone dust without having a negative impact on the extent of carbonation, and thus on the durability of the reinforced concrete structure.

The disintegration of concrete structures made of ordinary Portland cement (OPC) is a worrying topic of increasing significance. The trend for reusing waste products or industrial by-products to reduce the amount of OPC in concrete constructions has become an important task for industries and research institutions. Although OPC is an essential ingredient for concrete and is immensely popular, it greatly ‎contributes to the release of a massive quantity of CO2 into the atmosphere. To decrease the ‎increasing CO2 emission, scholars and researchers in the construction industry and ‎academic institutions have exerted efforts to adopt alternative sustainable binders using ‎pozzolanic materials, such as metakaolin, fly ash, slag, rice husk ash, and ‎palm oil fuel ash, combined with alkali-activator (AA). Many researchers have ‎stated that AA alumina-silicate (Al2SiO2) materials can produce convincing mechanical ‎and durability properties, such as compressive strength, splitting tensile strength, and ‎modulus of elasticity, in cement concrete at an early age with low CO2 emission and ‎energy consumption. Most researchers have reported that concrete containing pozzolanic materials and alkali-activated binder (AAB) has better durability than conventional concrete, while others call for further studies. According ‎to previous studies, this research assesses the present studies on the mechanical and ‎durability properties of cement concrete produced from the AAB related to the ‎pozzolanic materials. Furthermore, few possible studies have been recommended in the ‎future‎.

Induction furnace dust (IFD) is a waste product of the alloy-making process whose disposal by landfill process becomes unsafe due to the presence of heavy metals in high concentrations. It further reduces the fertility of soil and pollutes the air making it harmful for human health. However, efforts can be made to utilize this dust in construction material as it has the same oxides (silica, aluminium oxide, and magnesium oxide) as found in cement, bricks, fine aggregates, coarse aggregates, etc. This study is aimed at the utilization of pre-treated induction furnace dust with Aspergillus niger fungus to replace cement for the construction of concrete structures through Taguchi design of experiments (DOE). The purpose of Aspergillus niger fungus is to reduce the heavy metal concentration from IFD to prevent the surroundings from getting toxic. The optimization of operating parameters such as dust replacement (5%, 10%, and 15%), curing days (7, 14, and 28 days), and cell count of fungus (104, 106, and 108 CFU/ml of distilled water) is done using Multi-objective Genetic Algorithm (G.A.) for effective compressive strength and water absorption capacity of cubes. The best results have been found in the case of IFD treated with Aspergillus niger fungus having dust replacement, curing time, and cell count of 14.96%, 28 days, and 9.22 × 107 CFU/ml of distilled water respectively for concrete production. [ABSTRACT FROM AUTHOR]

This paper focuses on the investigation of the material properties of FC500 foam concrete. Innovation is very important for the solution of cast-in-place concrete forms in practice today. Part of its innovative construction application is the possibility of using foam concrete in a composite structure and the use of its mechanical properties in the load-bearing parts of civil engineering structures. The method of detecting the mechanical properties of foam concrete by using non-standard cantilever test is also innovative. Here, an advanced approach of modelling specimens using powerful computational systems based on the finite element method is used. This modern material is researched especially for its use in transportation structures. For its application, it is necessary to define its resistance to mechanical loads. The main content of the research consists of correlations between experimental measurements and analytical and numerical results. This is the principle of quasi-linear identification of the non-linear behavior of polymeric cementitious porous material during tests on specimens. The focus of the research is an extensive experiment: measurements of the deformation of the specimens until failure. The following methods were chosen to investigate the material properties: small cantilever test, standard tensile test and compression test. The cantilever test was performed for the individual components of the FC500 composite and cement concrete, but also as a compact composite. Numerical simulation models were developed to correlate the individual results in order to validate the uniaxial test results. The conclusions of the research led to the definition of standardized stress–strain diagrams of the FC500 material for compression and especially tension. This is a definition of the behavior of this polymer composite, usable for the development of numerical models of full-scale structures. The results of the research will be applied in the development of national standards for the use of advanced materials in transportation structures (cycle paths, parking lots, traffic playgrounds, lightly trafficked forest roads and trails, etc.). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, mesoscale modeling is performed to simulate and understand fracture behavior of two concrete composites: cement and asphalt concrete using disk-shaped compact tension (DCT) tests. Mesoscale models are used as alternative to macroscale models to obtain better realistic behavior of composite and heterogeneous materials such as cement and asphalt concrete. In mesoscale models, aggregate and matrix are represented as distinct materials and each material has its characteristic properties. Disk-shaped compact tension test is used to obtain tensile strength and fracture energy of materials. This test can be used as a better alternative to other tests such as three points bending tests because it is more convenient for both field and laboratory specimens in addition to its accurate results. Comparing the numerical results of the mesoscale models of cement and asphalt concrete specimens with experimental data shows that these models can predict the behavior of these composite materials very well as seen in the curves of load-crack mouth opening displacement (CMOD). Also, the mesoscale modeling highlights the variability of crack direction where it is dependent on the random distribution of aggregate.

The aim of this study is to investigate the effect of municipal solid waste incineration bottom ash from a cogeneration plant on the physical and mechanical properties and durability of cement concrete. Part of the cement in concrete mixtures tested was replaced with 0%, 3%, 6%, 9%, and 12% by weight of municipal solid waste incineration bottom ash. Concrete modified with 6% of bottom ash had a higher density (2323 kg/m3), compressive strength at 28 days (36.1 MPa), ultrasonic pulse velocity (3980 m/s), and lower water absorption rate (3.93%). The tests revealed that frost resistance, determined in all-sided testing directions, of concrete modified with 6%, 9%, and 12% of bottom ash added by weight of cement corresponds to strength grade F100. Such concrete can be used in construction works. [ABSTRACT FROM AUTHOR]

In the deck under the background of cement concrete pavement disease is increasing, in order to analyze the vehicle mechanics performance of asphalt concrete under dynamic loading, to improve the surfacing layer use effect and shear failure conditions, based on the theory of the Coulomb made by indoor experiment of cylindrical concrete block, using Hopkinson pressure bar（SHPB） test units on test block of different impact load, the failure mode, dynamic compressive strength and stress-strain characteristics of different strength cement concrete test blocks were studied. The results show that the failure of cement concrete test block caused by impact load is from block failure to crushing failure. The impact load can enhance the compressive strength of concrete, especially for the cement concrete with low strength, and the dynamic compressive strength enhancement rate is up to 143.7%. Under the action of dynamic mechanics, the stress-strain curve of cement concrete also presents four stages. With the increase of strain, the slope of the stress-strain curve of cement concrete becomes smaller, and it changes from strain hardening to strain softening. The analysis of physical and mechanical characteristics of cement concrete under dynamic load can provide some reference value for the improvement of strength and performance of cement concrete pavement of engineering bridge deck. [ABSTRACT FROM AUTHOR]