Search Results (42)

Water ingress and penetration of aggressive fluids undermines the integrity of many concrete structures. For this reason, optimal performance of such structures up to their designed life cannot be guaranteed. This study introduces nano silicon as an alternative waterproofing admixture for increasing life span of cementitious materials, due to its non-vulnerability to deterioration, which is common to traditional surface coating solutions. Therefore, nano silicon was characterized using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersion Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and surface Zeta potential. The Central Composite Design (CCD) tool was adopted to plan the experiment and further used to model the relationship between experimental variables and experimental response. The model was found to be nonlinear quadratic based on Analysis of Variance (ANOVA). Also, the validity of the model was evaluated and found to have accurate prediction with mean absolute percentage error (MAPE) of 1.62%. The optimum mix ratio necessary to increase resistance to capillary water absorption was established at a nano silicon dosage of 6.6% by weight of cement and w/c of 0.42. In conclusion, the overall results indicate that resistance to capillary water absorption was increased by 62%. Furthermore, while gas permeability was reduced by 31%, on the other hand, volume of water permeable voids decreased by 10%. Full article

Underground structures are subject to deterioration conditions in which water leakage occurs through cracks due to the long-term influence of soil and groundwater. Therefore, composite waterproofing sheets can play an important role in securing the leakage stability of structures by combining them with concrete structures. In this study, a total of eight composite waterproofing sheets were used according to the thickness of the compound and the properties of the material attached to the concrete, and the deformation characteristics at the bonding surface were identified through repeated tensile tests. Types A, B, and C, with a compound thickness of 1.35 to 1.85 mm and a single layer, had strong bonding performance, with a deformation rate of 0.5 to 2 × 10⁻⁴ and a DE/RE ratio of 0.3 to 1.3; tensile deformation progressed while maintaining integrity with the concrete at the bonding surface. Types D and E were viscoelastic and non-hardening compounds with a compound thickness of 1.35 to 3.5 mm, where the strain rate due to tensile deformation was the lowest, at 0.1 × 10⁻⁴ or less, and the DE/RE ratio was −5 to 3; therefore, when internal stress occurs, the high-viscosity compound absorbs it, and the material is judged to have low deformation characteristics. Types F, G, and H, which were 2 to 2.9 mm thick and had two layers using a core material, were found to have characteristics corresponding to tensile deformation, as the strain rate increased continuously from 0.2 to 0.5 × 10⁻⁴, and the DE/RE ratio increased up to 8 mm of tensile deformation. Full article

To apply the cementitious capillary crystalline waterproof materials (CCCWs) in real engineering practice, the mechanical properties and related mechanism of cement after adding CCCW are investigated in this study. By using a combination of techniques including X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and mercury intrusion porosimetry, the effect of Penetron (PNC, a kind of CCCW) content on the microstructure and compressive strength of cement with different water-to-bind (w/b) ratio were studied. The results show that the high-water content definitely decreased the mechanical properties of cement pastes. The addition of PNC appeared to play a detrimental role in the 7 d compressive strength due to the lower reactivity of PNC than cement. As the PNC content increased from 0% to 1.5%, the 28 d compressive strength of cement pastes increased despite the w/b ratio. For cement pastes with a w/b ratio of 0.50, its 28 d compressive strength increased from 24.6 MPa to 32.9 MPa. This can be attributed to the sulfate/carbonate-containing species in PNC to react with cement to form suitable ettringite. Consequently, the microstructure became denser, and porosity decreased. As PNC content increased to a further 2.5%, the compressive strength of cement pastes decreased gradually. The excessive PNC caused the excess ettringite, which destroyed the microstructure and increased the porosity of cement pastes. This study demonstrated that the PNC and its dosage affected the microstructure and the mechanical properties of cement paste. Suitable content, normally 1.5%, is recommended to apply in cement paste considering the mechanical properties despite the w/b ratio. Full article

Flexible pressure sensors have drawn growing attention in areas like human physiological signal monitoring and human–computer interaction. Nevertheless, it still remains a significant challenge to guarantee their long-term stability while attaining a wide detection range, a minute pressure testing limit, and high sensitivity. Inspired by the wrinkles on animal skins, this paper introduces a flexible pressure sensor with wrinkled microstructures. This sensor is composed of a composite of reduced graphene oxide (rGO), single-walled carbon nanotubes (SWCNTs), and polydimethylsiloxane (PDMS). After optimizing the proportion of the composite materials, the flexible pressure sensor was manufactured using highly efficient heat-shrinkable films. It has a sensitivity as high as 15.364 kPa⁻¹. Owing to the wrinkled microstructures, the sensor can achieve an ultra-wide pressure detection range, with the maximum reaching 1150 kPa, and is capable of detecting water wave vibrations at the minimum level. Moreover, the wrinkled microstructures were locked by PDMS. The sensor acquired waterproof performance and its mechanical stability was enhanced. Even after 18,000 cycles of repeated loading and unloading, its performance remained unchanged. By combining with an artificial neural network, high-precision recognition of different sounds and postures when grasping different objects was realized, with the accuracies reaching 98.3333% and 99.1111%, respectively. Through the integration of flexible WIFI, real-time wireless transmission of sensing data was made possible. In general, the studied sensor can facilitate the application of flexible pressure sensors in fields such as drowning monitoring, remote traditional Chinese medicine, and intelligent voice. Full article

In recent years, wind energy has emerged as one of the fastest-growing green technologies globally, with projections indicating that decommissioned wind turbine blades (WTBs) will accumulate to millions of tons by the 2030s. Due to their thermosetting nature and high glass/carbon fiber content, the efficient recycling of WTBs remains a challenge. In this study, we utilized solid-state shear milling (S3M) to produce a fine WTB powder, which then underwent surface modification with a silane coupling agent (KH550), and we subsequently fabricated WTB-reinforced polypropylene (PP) composites with enhanced mechanical performance through solid-state stretching. The stretching-process-induced orientation of the PP molecular chains and glass fibers led to orientation-induced crystallization of PP and significant improvements in the mechanical properties of the PP/WTB@550 composites. With 30 wt. % WTB content, the PP/WTB@550 composite achieved a tensile strength of 142.61 MPa and a Young’s modulus of 3991.19 MPa at a solid-state stretching temperature of 110 °C and a stretching ratio of 3, representing increases of 268% and 471%, respectively, compared to the unstretched sample. This work offers both theoretical insights and experimental evidence supporting the high-value recycling and reuse of WTBs through a cost-effective, environmentally friendly, and scalable approach. Due to the enhanced mechanical properties of the PP/WTB composite and the intrinsic waterproofing and corrosion resistance of PP, it is hoped that such a composite would be used in road engineering and building materials, such as geogrids, wall panels, floor boards, and floor tiles. Full article

Most earthen sites are located in open environments eroded by wind and rain, resulting in spalling and cracking caused by shrinkage due to constant water absorption and loss. Together, these issues seriously affect the stability of such sites. Gypsum–lime-modified soil offers relatively strong mechanical properties but poor water resistance. If such soil becomes damp or immersed in water, its strength is significantly reduced, making it unviable for use as a material in the preparation of earthen sites. In this study, we achieved the composite addition of a certain amount of sodium methyl silicate (SMS), titanium dioxide (TiO₂), and graphene oxide (GO) into gypsum–lime-modified soil and analyzed the microstructural evolution of the composite-modified soil using characterization methods such as XRD, SEM, and EDS. A comparative study was conducted on changes in the mechanical properties of the composite-modified soil and original soil before and after immersion using water erosion, unconfined compression (UCS), and unconsolidated undrained (UU) triaxial compression tests. These analyses revealed the micro-mechanisms for improving the waterproof performance of the composite-modified soil. The results showed that the addition of SMS, TiO₂, and GO did not change the crystal structure or composition of the original soil. In addition, TiO₂ and GO were evenly distributed between the modified soil particles, playing a positive role in filling and stabilizing the structure of the modified soil. After being immersed in water for one hour, the original soil experienced structural instability leading to collapse. While the water absorption rate of the composite-modified soil was only 0.84%, its unconfined compressive strength was 4.88 MPa (the strength retention rate before and after immersion was as high as 93.1%), and the shear strength was 614 kPa (the strength retention rate before and after immersion was as high as 96.7%). Full article

The decks of steel–concrete composite bridges are constantly exposed to severe environmental conditions, which frequently give rise to significant issues, including cracks and holes. These problems occur due to the formation of blisters under the paving layer with waterproofing membranes. This paper aims to delve into the characteristics of blisters during their expansion and propagation stages. Additionally, it proposes a rating index and a simplified calculation formula to assess the interface propagation performance of bridge deck pavement. To achieve this, the research group developed a simulated blister test device and employed the digital image correlation (DIC) technique. The study investigated the impact of pavement structure, waterproofing layer, and air voids on blister propagation behavior. It was discovered that the pavement blister test encompassed two distinct stages: expansion and propagation. Furthermore, the SMA-13 asphalt mixture exhibited slightly superior resistance to blistering compared to AC-13. It was also observed that when the mixture void ratio is less than 3.5%, it becomes more susceptible to blistering deformation, ultimately leading to debonding damage. Among the waterproofing materials tested, SBS-modified emulsified asphalt demonstrated the weakest adhesion to cement concrete substrates, while SBS-modified asphalt performed slightly better than rubberized asphalt. Full article

The purpose of the research described in this article was to optimize the compositions based on hydraulic-modified binder and construction waste for waterproofing and repair of concrete or brick structures in contact with the ground, as well as the study of properties and development of the basis of the methodology for selecting the composition of such a waterproofing system. Processing of the results of the experiment was carried out by statistical and analytical methods. The research was based on a method for determining the adhesive strength of a waterproofing coating, based on the determination when the insulating layers are torn off. As a result of the calculation and experimental verification, the composition of the waterproofing material was obtained, which corresponds to an adhesive strength of 3.8 MPa; the strength of the waterproofing layer was 36–37 MPa, as well as the amounts of the main components: acrylic resin 3.9%; finely ground concrete waste 80 kg/m³; plasticizer consumption (0.38…0.39%) at the optimum moisture content of the base surface (9.7…9.8%). Full article

In this study, ground polymers were prepared from mudstone and slag. NaOH and water glass were used as alkaline exciters and mine waste rock aggregate was used as the aggregate for mudstone slag-based waterproof composites (MSWCs). A series of laboratory tests, including a uniaxial compression test, uniaxial cyclic loading and unloading test, scanning electron microscope test, and rock penetration test were conducted for macrostructural and microstructural analysis. The effect of the coupling between the mudstone proportion and the number of uniaxial cyclic loading and unloading tests was investigated. The results showed that it is feasible to use mudstone and slag to synthesize geopolymers, and that MSWCs fulfil the conditions for use as a reconstituted water barrier. The permeability of MSWCs with the different mudstone proportions set in this study fulfils the requirement of being used as a material, and the permeability and uniaxial compressive strength of the MSWCs gradually decreased with increases in the mudstone proportion. Considering the UCS and permeability of the MSWCs, the optimal mudstone proportion of the MSWC is r = 0.6. In this test, cyclic loading and unloading times of 0, 25, 50, and 100 were set, and with an increase of cyclic loading and unloading times, the UCS of the MSWCs showed a tendency of increasing first and then decreasing. In the SEM test, with an increase of cyclic loading and unloading times, microfractures and pores appeared in the MSWCs, which led to a gradual increase in its permeability and a decrease in its waterproofness. Full article

Crystalline coatings are waterproofing systems used for additional protection against increased moisture and subsurface water ingress. Even though these crystalline materials are commonly used in moisture-protective systems, they have not yet been sufficiently scientifically described. The weakest link in the chain of interaction between crystalline coatings and underlying concrete is the transition zone. To increase knowledge of the interaction between these materials, a series of experiments was prepared using a specially formulated protective mortar as the final surface layer, with the function of additionally waterproofing the structure. An experimental study of the adhesion of surface layers based on secondary crystallization to provide additional protection to concrete structures loaded with moisture or ground water exposure is presented in this paper. The series of experiments carried out consisted of an analysis of protective crystalline mortar adhesion to concrete samples of identical composition. A set of experimental measurements under the influence of various boundary conditions was carried out to determine the bond strength between two different materials. For the experimental measurements, the materials were exposed to aggressive environments for which durability verification had not yet been performed. A modified protective mortar with crystalline admixture was used as an overlayed material. This mortar worked similarly to a crystalline coating after application. Over time, there was penetration of the underlaying concrete and a secondary hydration of the cement matrix which resulted in the waterproofing of the structure. The test samples were exposed to aggressive environmental conditions in the form of freezing–thawing cycles and a carbonation process. Pull-off tests were carried out on every test sample to determine the strength of the surface layers. The penetration of the crystalline agent into the base concrete was confirmed with an SEM observation. The results of the experimental program showed that exposure to the aggressive environment further reduced the strength of the modified mortar containing the crystalline admixture. However, the bond strength between the concrete and the modified mortar exceeded the tensile strength of the concrete. Full article

In Korea, large-scale apartment projects often give rise to disputes among residents, which have prompted implementation of the “Apartment Performance Rating System” by the Ministry of Land, Infrastructure, and Transport. In addition, disputes related to leakage defects in apartment structures are increasing, especially in underground spaces of joint residential complexes. This study aims to identify waterproofing materials and methods for specific underground structure components through experimental evaluations and to assign waterproofing performance ratings similar to existing apartment house grades. These performance ratings will serve as foundational data to prevent leakage in joint residential complexes. This study proposes composite and self-adhesive sheet waterproofing as effective methods, emphasizing the significance of sheet waterproofing materials for excellent performance. The need for improved waterproofing materials to address long-term permeability issues is also highlighted. This research provides essential data for future waterproofing performance ratings; therefore, contributing to construction quality and safety in joint residential complexes. Full article

A comprehensive characterization of the physical and chemical properties of whole duck feathers from French mulard species, including their various categories and fractions (barbs, rachis, and calamus), was conducted to explore potential ways for utilizing this waste product. This analysis aimed to identify opportunities for valorizing these feathers and unlocking their untapped potential. Hence, the duck feathers were thoroughly characterized by a proximate analysis to determine their composition and theoretical heating value. Additionally, feathers underwent other analyses as Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis, solvent behavior and chemical durability assessment, hydrophobicity testing, Fourier Transform Infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The analyses revealed duck feather composition, molecular weight, stability in different environments, hydrophobicity, functional groups present, thermal behavior, crystallinity, and structural arrangement. Upon analysis, it was determined that duck feathers contain pure fiber keratin and possess characteristics that make them suitable for the production of high-value keratin-based products, including cosmetics, activated carbon for purification, materials for waterproofing, lightweight construction, and textile innovations, underscoring their potential to support sustainable and eco-friendly initiatives across various sectors. Full article

This study evaluates waterproofing methods for underground structures in multi-unit residential buildings. The objective is to select effective methods and establish performance ratings. Experimental assessments are conducted and scores are assigned for ranking. In this regard, waterproofing methods used in the upper slab of the top floor of multi-unit residential building underground structures were investigated, and they were categorized as composite waterproofing, sheet waterproofing, and membrane waterproofing methods. For performance evaluation purposes, experiments were conducted on qualified materials and scores were assigned to each test specimen, with a total score of 100 points. Based on the test results, scores for disqualified materials were deducted and, ultimately, the rankings of waterproofing materials and methods for the upper slab of the top floor of underground structures were determined based on the total aggregated scores. Subsequently, through proximity performance evaluation, the applied waterproofing methods were experimentally verified for defect issues based on the presence or absence of a proximity layer. This led to the ranking and performance grading of a total of 12 materials. The results confirmed the necessity of a proximity layer-dependent waterproofing method and highlighted the superiority of the composite waterproofing method with a proximity layer. Additionally, differences in installation methods and material properties between sheet and membrane waterproofing methods were identified, resulting in variations in performance grading. Full article

The special particle grading properties of silt lead to the strong water sensitivity and low soil strength of silt sites, many of which are severely damaged and urgently need to be repaired. This article takes the powder soil from a certain burial site area in Xizhu Village, Luoyang as the research object, which is improved by adding nanosilica and potassium methylsilicate. The modified soil is studied through mechanical and waterproof performance tests, and the mechanism of action of the modified material is analyzed through SEM and XRD. The experimental results show that the mechanical properties and waterproof properties of the composite modified soil were improved when the nanosilica content was 2% and the potassium methylsilicate content was 0.5%; the durability of the composite modified soil is improved, making this the optimum ratio. The mechanical properties and water resistance of the silty soil were significantly improved by adding the appropriate amount of nanosilica and potassium methylsilicate. Nanosilica can be evenly dispersed in the soil matrix, absorb a small amount of water to form a gel state, fill the pores in the silt aggregates, and improve soil compactness. In addition, nanosilica aggregates can attach to the surface of the soil particles and extend from the particle surface to the particle edge. By increasing the contact between soil particles and increasing the particle size, the mechanical properties of the modified soil are improved. When potassium methylsilicate solution is added to the soil, it reacts with water and carbon dioxide, decomposes into methylsilicate, and quickly generates a polymethylsiloxane film to cover the surface of soil particles, forming a waterproof film on the surface and thereby improving the waterproof performance of modified soil. Our research results can provide a reference for the restoration and protection of silty and silt-like sites. The next step is to apply the composite modified soil in engineering restoration through field tests in order to study the repairing ability of composite modified soil and its actual protective effects. Full article

This research paper systematically investigates the combined influence of fly ash, cementitious capillary crystalline waterproofing (CCCW) materials, and polypropylene fibers on the mechanical properties and impermeability of concrete through comprehensive orthogonal tests. Microscopic morphological changes in the concrete induced by different composite materials are examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) testing. The objective is to facilitate a beneficial synergetic interaction among these materials to develop highly permeable, crack-resistant concrete. Key findings of this study are: (1) The study unveils the impact of the concentration of three additive materials on the concrete’s compressive strength, tensile strength, and penetration height, thereby outlining their significant influence on the mechanical properties and impermeability of the concrete; (2) An integrated scoring method determined the optimal composite dosage of three materials: 15% fly ash, 2% CCCW, and polypropylene fibers at 1.5 kg/m³. This combination increased the concrete’s compressive strength by 12.5%, tensile strength by 48.4%, and decreased the average permeability height by 63.6%; (3) The collective introduction of these three materials notably augments the hydration reaction of the cement, resulting in denser concrete microstructure, enhanced bonding between fibers and matrix, and improved concrete strength and durability. Full article