Search Results (141)

Concrete structures increasingly face dynamic loading conditions, such as seismic events, vehicular traffic, and environmental vibrations, necessitating enhanced energy dissipation capabilities. The damping ratio, a critical parameter quantifying a material’s ability to dissipate vibrational energy, is typically low in conventional concrete, prompting extensive research into strategies for improvement. This review comprehensively explores the impact of advanced concrete types—such as Engineered Cementitious Composites (ECCs), Ultra-High-Performance Concrete (UHPC), High-Performance Concrete (HPC), and polymer concrete—on enhancing the damping behavior. Additionally, key mix design innovations, including fiber reinforcement, rubber powder incorporation, and aggregate modification, are evaluated for their roles in increasing energy dissipation. External factors, particularly curing conditions, are also discussed for their influence on the damping performance. The findings consolidate experimental and theoretical insights into how material composition, mix design, and external treatments interact to optimize dynamic resilience. To guide future research, this paper identifies critical gaps including the need for multi-scale numerical simulation frameworks, standardized damping test protocols, and long-term performance evaluation under realistic service conditions. Advancing work in material innovation, optimized mix design, and controlled curing environments will be essential for developing next-generation concretes with superior vibration control, durability, and sustainability. These insights provide a strategic foundation for applications in seismic-prone and vibration-sensitive infrastructure. Full article

This paper reviews the applications and performance advantages of ultra-high-performance concrete (UHPC), engineered cementitious composite (ECC), and recycled aggregate concrete (RAC) in composite flexural members. UHPC is characterized by its ultra-high strength, high toughness, excellent durability, and microcrack self-healing capability, albeit with high costs and complex production processes. ECC demonstrates superior tensile, flexural, and compressive strength and durability, yet it exhibits a lower elastic modulus and greater drying shrinkage strain. RAC, as an eco-friendly concrete, offers cost-effectiveness and environmental benefits, although it poses certain performance challenges. The focus of this review is on how to enhance the load-bearing capacity of composite beams or slabs by modifying the interface roughness, adjusting the thickness of the ECC or UHPC layer, and altering the cross-sectional form. The integration of diverse concrete materials improves the performance of beam and slab elements while managing costs. For instance, increasing the thickness of the UHPC or ECC layer typically enhances the load-bearing capacity of composite beams or plates by approximately 10% to 40%. Increasing the roughness of the interface can significantly improve the interfacial bond strength and further augment the ultimate load-bearing capacity of composite components. Moreover, the optimized design of material mix proportions and cross-sectional shapes can also contribute to enhancing the load-bearing capacity, crack resistance, and ductility of composite components. Nevertheless, challenges persist in engineering applications, such as the scarcity of long-term monitoring data on durability, fatigue performance, and creep effects. Additionally, existing design codes inadequately address the nonlinear behavior of multi-material composite structures, necessitating further refinement of design theories. Full article

This paper proposes a steel-ECC ordinary concrete composite continuous bridge deck structure to address the cracking problem of simply supported beam bridge deck continuity. Through theoretical and experimental research, a high-performance ECC material was developed. The ECC material has a compressive strength of 57.58 MPa, a tensile strain capacity of 4.44%, and significantly enhanced bending deformation ability. Bonding tests showed that the bond strength of the ECC-reinforcing bar interface reaches 22.84 MPa when the anchorage length is 5d, and the splitting strength of the ECC-concrete interface is 3.58 MPa after 4–5 mm chipping treatment, with clear water moistening being the optimal interface treatment method. Full-scale tests indicated that under 1.5 times the design load, the crack width of the ECC bridge deck continuity structure is ≤0.12 mm, the maximum deflection is only 5.345 mm, and the interface slip is reduced by 42%, achieving a unified control of multiple cracks and coordinated deformation. The research results provide a new material system and interface design standards for seamless bridge design. Full article

Engineered cementitious composites (ECCs), known for their superior ductility and strain-hardening behavior compared to conventional concrete, have been predominantly studied with polyvinyl alcohol (PVA) fibers. However, the potential economic and technical advantages of incorporating steel fibers into ECCs have been largely overlooked in the literature. This study investigates the mechanical performance of ECC reinforced with different types of steel fibers, including straight, twisted, hooked, and hybrid fibers of different lengths, as compared to PVA. The inclusion of various supplementary cementitious materials (SCMs) such as slag and fly ash with each type of steel fiber was also considered at a constant fiber volume fraction of 2%. The mechanical properties were assessed through compressive strength, splitting tensile strength, and four-point flexural tests along with calculations of toughness, ductility, and energy absorption capacity indices. This study compares the mechanical properties of different ECC compositions, revealing that ECCs with hybrid steel fibers (short and long) achieved more than twice the tensile strength, 12.7% higher toughness, and 36.4% greater energy absorption capacity compared to ECCs with PVA fibers, while exhibiting similar multiple micro-cracking behavior at failure. The findings highlight the importance of fiber type and distribution in enhancing an ECC’s mechanical properties, providing valuable insights for developing more cost-effective and resilient construction. Full article

This paper investigates the effects of the basalt-fiber-reinforced polymer (BFRP) and polyethylene (PE) hybrid fiber ratio on the mechanical properties and durability of engineered cementitious composites (ECC). First, four different PE-BFRP hybrid fiber ECC mixtures were systematically prepared by controlling the fiber volume ratio of PE and BFRP fibers. The workability and mechanical properties of the hybrid fiber ECC (HFECC) were then evaluated using flowability tests and multi-scale mechanical tests, including compressive strength, flexural strength, bending toughness, and tensile performance. After that, the durability of HFECC with different fiber ratios was comprehensively assessed through freeze–thaw cycle tests and rapid ion migration tests. Finally, the interface morphology of fibers within the matrix was observed using scanning electron microscopy (SEM). The results show that an appropriate hybrid of PE and BFRP fibers can synergistically enhance the crack resistance and toughness of ECC, improving its failure mode. The best performance in terms of flowability and mechanical properties was observed for the HFECC mixture with 1.30% PE fiber volume and 0.30% BFRP fiber volume. With the increase in BFRP fiber content, the freeze–thaw resistance and chloride ion erosion resistance of HFECC were gradually enhanced. This study provides experimental and theoretical support for the design and engineering application of high-performance hybrid fiber ECC materials. Full article

To enhance the mechanical properties of a precast monolithic column, the ECC material was made into a prefabricated shell with reinforced bars. Post-cast concrete was poured into the precast parts to form the reinforced ECC precast monolithic composite columns. An axial compression test was conducted to investigate the failure pattern, load-bearing capacity, and deformation performance. The results showed that the R/ECC composite columns had good integrity. The R/ECC prefabricated shell exerted an extra confinement effect on the column and enhanced deformability. At the yield stage, the displacement of the reinforced ECC prefabricated columns was 16.19% greater than that of RC composite columns on average. Additionally, the maximum load point displacement exhibited 15.30% growth. The ECC material delayed the yield time of longitudinal bars and stirrups. Before reaching the maximum load, the strains in the R/ECC composite column rebars were smaller than those in the RC column rebars. At the maximum loading point, the longitudinal reinforcement exhibited a 9.36% greater strain than that of the RC composite column. Full article

This paper presents an analysis of energy use and sector coupling in a local energy community using a model based on energy cost centres (ECCs), functional units for decentralised responsibility and optimisation of energy use within defined system boundaries. The ECC model enables structured identification and optimisation of energy and material flows in complex industrial and urban settings. It was applied to a case study involving an energy-intensive steel plant and its integration with the surrounding community. The study assessed the potential for renewable electricity production (7914 MWh annually), green hydrogen generation, battery storage, and the reuse of 11,440 MWh of excess heat. These measures could offset 9598 MWh of grid electricity through local production and savings, reduce natural gas use by 4,116,850 Nm³, and lower CO₂ emissions by 10,984 tonnes per year. The model supports strategic planning by linking sectoral actions to measurable sustainability indicators. It is adaptable to data availability and stakeholder engagement, allowing both high-level overviews and detailed analysis of selected ECCs. Limitations include heterogeneous data sources, uneven stakeholder participation, and the need for refinement of sub-models. Nonetheless, the approach offers a replicable framework for integrated energy planning and supports the transition to sustainable, decentralised energy systems. Full article

This study explores the influence of the water–cement ratio and fiber content in engineered cementitious composite (ECC) on the mechanical characteristics of foamed lightweight soil (FLS) through experimental analysis. Two types of cementitious materials—ECC and ordinary Portland cement (OPC)—were utilized to create FLS specimens under identical parameters to examine their mechanical performance. Results indicate that ECC-FLS exhibits superior toughness, plasticity, and ductility compared to OPC-FLS, validating the potential of ECC as a high-performance material for FLS. To assess the influence of the ECC water–cement ratio, specimens were constructed with varying ratios at 0.2, 0.25, and 0.3, while maintaining other parameters as constant. The experimental results indicate that as the water–cement ratio of ECC increases, the flexural strength, compressive strength, flexural toughness, and compressive elastic modulus of the lightweight ECC-FLS gradually increase, exhibiting a better mechanical performance. Moreover, this study investigates the effect of basalt fiber content in ECC on the mechanical properties of FLS. While keeping other parameters constant, the volume content of basalt fibers varied at 0.1%, 0.3%, and 0.5%, respectively. The experimental results demonstrate that within the range of 0 to 0.5%, the mechanical properties of FLS improved with increasing fiber content. The fibers in ECC effectively enhanced the strength of FLS. In conclusion, the adoption of ECC and appropriate fiber content can significantly optimize the mechanical performance of FLS, endowing it with broader application prospects in engineering practices. ECC-FLS, characterized by excellent ductility and crack resistance, demonstrates versatile engineering applications. It is particularly suitable for soft soil foundations or regions prone to frequent geological activities, where it enhances the seismic resilience of subgrade structures. This material also serves as an ideal construction solution for underground utility tunnels, as well as for the repair and reconstruction of pavement and bridge decks. Notably, ECC-FLS enables the resource utilization of industrial solid wastes such as fly ash and slag, thereby contributing to carbon emission reduction and the realization of a circular economy. These attributes collectively position HDFLS as a sustainable and high-performance construction material with significant potential for promoting environmentally friendly infrastructure development. Full article

Extended-chain crystals (ECCs) of poly(butylene succinate) (PBS), featuring highly ordered molecular chains and exceptional thermal stability with a melting point 25 °C higher than conventional folded-chain crystals, demonstrate remarkable potential as nucleating agents for PBS crystallization. The incorporation of 5 wt% ECCs leads to a 12 °C increase in crystallization temperature and reduces crystallization half-time by 88% at 98 °C. Most significantly, self-nucleation studies reveal an unprecedented expansion of Domain II temperature window (∆T = 30 °C), exhibiting enhanced melt memory effects and a broadened processing window. Rheological investigations uncover the formation of unique intermolecular interactions in the melt, evidenced by non-terminal viscoelastic behavior and reduced loss tangent at elevated temperatures, with complementary evidence from higher ECC loadings confirming these findings. This local ordered structure exhibits remarkable thermal stability, persisting even above the melting point through specific intermolecular interactions, leading to the melt memory effect. These findings establish a new paradigm for nucleation control in biodegradable polyesters and provide molecular design strategies for high-performance sustainable materials. Full article

The combination of fiber reinforced polymer (FRP) and engineered cementitious composite (ECC) has emerged as a promising method for strengthening reinforced concrete (RC) structures. By embedding FRP within an ECC to form a composite reinforcement layer, the advantages of both materials can be effectively harnessed, and the dense ECC matrix can be employed to safeguard FRP from adverse environments. Significantly, the interface bonding property constitutes the key for the two materials to collaborate effectively. In light of the research gap related to the bonding performance of embedded FRP strips in ECC joints, this study conducted a bench-scale investigation into the pull-out behavior of carbon FRP (CFRP) strips within an ECC. The relationship between the average bonding strength (2.84 MPa~4.77 MPa) and the embedded length of FRP strips was established. Additionally, the pull-out mechanism of FRP strips within an ECC matrix was utilized to elucidate the influence of the embedded length on the distinct behavior of FRP strips within an ECC. An analytical method for predicting the full-range behavior of embedded FRP strip–ECC joints by using a trilinear bond–slip relationship was introduced. Four key parameters of the trilinear bond–slip relationship for embedded FRP strip–ECC joints were provided to meet the requirements of future engineering applications. Full article

Aim: Parents’ knowledge of oral health plays a key role in shaping their children’s habits and preventing early childhood caries, particularly through breastfeeding and nutrition. This study aimed to assess parents’ knowledge of how dietary habits affect both oral health and early childhood caries rates. Materials and methods: An online cross-sectional survey was conducted among 595 parents of children aged 3 to 6 years old using a self-structured questionnaire. Sociodemographic data, the children’s characteristics, breastfeeding practices, daily diet, the perceived effects of diet on orofacial health, and self-reported dental caries were recorded. The data were analyzed using descriptive statistics, chi-square tests, and regression models. Results: One-third of the children had dental caries (200/595). The prevalence of caries was significantly higher among children from rural areas (40.5%) compared to those from urban areas (31.1%) (p = 0.021) and in low-income families (72.7%) compared to middle-income (35.4%) and high-income (25.1%) families (p = 0.002). Breastfeeding duration, bottle feeding, and night feeding were not significantly associated with the occurrence of caries. Only 11.1% of parents recognized the role of extended breastfeeding on a child’s demand over one year in promoting the development of tooth decay. Better knowledge was observed among parents with university degrees, in healthcare workers, and in parents with lower incomes (p < 0.05). Conclusions: Dental caries was prevalent, especially among children from rural areas and low-income families. Although there is no direct correlation between the duration of breastfeeding and dental caries, parental awareness of the preventive benefits of breastfeeding remains low. Education for parents about breastfeeding and nutrition’s impact on oral health can have a substantial effect on preventing ECC. Educational efforts aimed at specific audiences are necessary to boost knowledge and advance preventive strategies. This study must recognize its limitations due to its dependence on self-reported caries data. Subsequent research must include clinical dental evaluations to achieve findings that are both dependable and factual. Full article

Background and Objectives: This study aimed to examine the influence of socio-demographic factors (marital status, number of children, and education level) on the knowledge, attitudes, and practices (KAP) concerning Early Childhood Caries (ECC) prevention among parents in Bihor, Romania. This research seeks to address the lack of regional data on the influence of socio-demographic factors, such as marital status, number of children, and education level, on parental knowledge, attitudes, and practices regarding ECC prevention. These insights are essential for developing targeted public health interventions in Romania. Materials and Methods: Conducted from March to September 2024, this cross-sectional study utilized a KAP questionnaire distributed online to parents of children under six. The survey was adapted to local contexts and included sections on demographic data and ECC-specific knowledge, attitudes, and practices. Statistical analyses, including Chi-square tests, were performed to evaluate the relationship between socio-demographic factors and KAP outcomes, ensuring robust data interpretation under ethical standards set by the Declaration of Helsinki. Results: Of the 798 respondents who accessed the questionnaire, 419 completed it, resulting in a completion rate of 52.5%. The participants had a mean age of 33.8 years. In terms of gender distribution, 348 (83.1%) were female and 71 (16.9%) were male. Higher educational levels were strongly correlated with better ECC knowledge and preventive practices; parents with university degrees demonstrated significantly better understanding and engagement in ECC prevention (p < 0.05). Married parents participated more actively in ECC prevention than unmarried ones, with 61.1% adhering to recommended practices compared to significantly lower rates among unmarried parents (p = 0.020). While this difference was statistically significant, the lower representation of unmarried parents in the sample should be considered when interpreting this finding. Families with fewer children showed more effective ECC preventive practices (p = 0.001). Conclusions: The study suggests that higher education and smaller family sizes are associated with better ECC prevention behaviors, emphasizing the need for targeted public health interventions. These could include parental education campaigns on ECC prevention, community-based oral health workshops, subsidized fluoride programs, and increased accessibility to pediatric dental services for underprivileged families. Full article

Background and Objectives: Severe early childhood caries (S-ECC) is a chronic infectious disease with a multifactorial etiology which has not been completely elucidated. Research on the role of oxidative stress in the etiopathogenesis of oral diseases suggests that the level of local antioxidants plays an important role in determining susceptibility to caries. This study aimed to demonstrate that the host’s redox imbalance, modified by genetic polymorphisms, may influence the onset and severity of S-ECC. Materials and Methods: A total of 110 patients were included in the study (59 diagnosed with S-ECC and 51 healthy controls). Upon initial appraisal, the DMFT (decayed-missing-filled teeth) index was determined, and epithelial cells were collected using oral swabs for genomic DNA extraction. Genotyping of SOD2 (rs4880) and GPX1 (rs1050450) was performed using TaqMan SNP genotyping assays and real-time polymerase chain reaction (PCR). Results: According to the results of the present study, there was a significant difference between the frequency of the reference genotype and variants for rs4880 (p = 0.0303). Subjects carrying the AG and GG variant genotype of rs4880 were significantly associated with a high DMFT value (p = 0.0005). However, no significant difference was found between the genotypes for rs1050450, nor was there an association with the severity of S-ECC. Conclusions: The AG and GG variant genotypes of the SOD2 polymorphism (rs4880) increase the severity of caries in preschoolers and predispose patients to develop carious lesions, especially when associated with certain feeding practices and infrequent toothbrushing. This observation emphasizes that host sensitivity to caries is a crucial factor in the onset and development of carious lesions in primary dentition, despite the main contributing factors to this pathology. The rs1050450 polymorphism was not associated with the severity of S-ECC. Full article

This paper examines the splitting tensile properties of rubberized polyethylene-engineered cementitious composites (RPECC) through static and dynamic experimental tests, highlighting the effects of thermal cycles, impact strain rates, and rubber powder substitution rates for fine aggregates. Damage patterns, ultimate tensile strength, time-dependent stress curves, dynamic failure strain, and the dynamic increase factor of the RPECC are presented. The microstructure of the material is analyzed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Experimental results reveal that incorporating rubber powders significantly enhances the deformability and ductility of RPECC in splitting tension. However, a high content of rubber powders, such as a substitution percentage of 30%, significantly reduces static and the dynamic ultimate tensile strength of the RPECC by 16.8% and 34.2%, respectively. Microstructural examinations indicate that thermal cycling weakens the internal adhesion between the rubber particles, polyethylene fibers, and the ECC matrix, resulting in the frequent withdrawal of fibers and the formation of calcium hydroxide, which diminishes the material tensile strength by up to 20.6% in static tests and 45.1% in dynamic tests. Despite these challenges, the RPECC with 20% rubber achieves a favorable balance between splitting the tensile properties and thermal resistance, even after undergoing 270 heat-cool cycles, suggesting its potential applicability in harsh environments. Full article

Background and Objectives: The aims of this study were to assess the impact of smoking on cervical histopathology in women with high-risk HPV types 16 and 18 (the most common types) utilizing comprehensive clinical data and to conduct a risk analysis based on smoking pack-years. Materials and Methods: Between 2022 and 2024, 1048 high-risk HPV-positive women aged 25 to 65 years were categorized into two groups: smokers and non-smokers. Data acquired from a histopathological examination of samples collected during a colposcopic evaluation of these women were compared individually regarding clinical and demographic factors, specifically age, gravida, parity, and alcohol consumption. Subsequently, the impact of prolonged and excessive smoking on histopathological cellular changes was assessed in women with the same characteristics. A case–control study was performed on 312 smokers and 312 non-smokers following mutual matching. Results: The women were matched one-to-one regarding gravida, parity, and alcohol consumption. Subsequently, they were paired within a ±2-year age range. The mean age of the smoker group was 47.1 ± 8.8, while that of the non-smoker group was 47.2 ± 8.5 (p: 0.904). In all cases of high-risk HPV positivity, the rate of normal cervical cytological results was 14% in women who smoked and 29% in women who did not smoke. The LGSIL, HGSIL, ASC-H, and AGC-NOS rates were elevated in the smoker group, and a statistically significant difference was observed between the two groups in terms of abnormal cervical cytological results (p < 0.001). After a colposcopic biopsy, the smoker group exhibited higher rates of HGSILs, LGSILs, AGC-NOS, and CIS pathological lesions (28% vs. 23%), whereas the non-smoker group exhibited higher rates of chronic cervicitis (23% vs. 16%). However, no statistically significant difference was found between the two groups (p: 0.092). In a comparison of endocervical curettage (ECC) samples, it was observed that the HGSIL, CIS, and AGC-FN rates in the smoker group were almost the same as those in the non-smoker group. However, the LGSIL histopathology results (32% vs. 18%) were higher, and the rate of negativity with no pathology was higher in the non-smoker group (72% vs. 59%). A statistically significant difference in ECC histopathology was noted between the two groups (p < 0.001). An ROC analysis conducted between smoking pack-years and the colposcopic and endocervical curettage biopsy results revealed that the cutoff value for the colposcopic abnormal histopathological results increased, with 40% sensitivity and 76% specificity above 20 pack-years (AUC: 0.592 and p: 0.025). Additionally, the abnormal histopathology rates for endocervical curettage exhibited 81% sensitivity and 32% specificity above 13 pack-years (AUC: 0.586 and p: 0.008). The rate of abnormalities in the colposcopic biopsy results was 2.19 times higher for individuals with over 20 pack-years, and the rate of abnormalities in the ECC results was 2.08 times higher for those with over 13 pack-years; additionally, statistically significant results were obtained (p-values of 0.027 and 0.008, respectively). Conclusions: The most important cause of neoplastic changes in the cervix uteri is high-risk HPV infection, with evidence indicating that prolonged excessive smoking significantly exacerbates the persistence and progression of HPV infection, thereby influencing neoplastic changes in the cervix uteri. It is crucial for women to cease smoking in order to eradicate HPV infection from the body. Full article