The Freeze-Thaw Strength Evolution of Fiber-Reinforced Cement Mortar Based on NMR and Fractal Theory: Considering Porosity and Pore Distribution

Zhang, Chaoyang; Liu, Taoying; Chong, Jong‐Wha; Chen, Zhao; Zhou, Keping; Chen, Lujie

doi:10.3390/ma15207316

Cited by 8 publications

(6 citation statements)

References 32 publications

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“…Confirmation of the above formulations was achieved through the examination of the mechanical property values presented in Figure 11. The mortars that were subjected to freeze-thaw cycles displayed, in most cases, advanced E and mechanical properties at the end of the experiment (due to cement hydration), while the porosity decreased due to a reduction in pores/voids [55]. On the other hand, outdoor exposure led to a porosity increment and E reduction, likely as a result of microcrack formations.…”

Section: Weathering Performancementioning

confidence: 94%

“…Nevertheless, in relation to the volume deformation, the C'R and C'pn compositions displayed the highest dimensional stability. The gradual increase in the specimens' dynamic moduli of elasticity indicated the evolution of the cement hydration process at these first stages of freeze-thaw cycles, which overcame the freeze-thaw effect due to the phase change in the water inside the material's voids [55]. Moreover, the fibres' role was probably not significant yet since the deterioration process was not fully developed [34].…”

Section: Weathering Performancementioning

confidence: 99%

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Evaluation of Hydrothermally Treated Wood Fibre Performance in Cement Mortars

Kampragkou,

Kamperidou,

Stefanidou

2024

Fibers

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Biofibres’ wide application in mortar enhancement has thus far been restricted by factors related to their chemical composition and hygroscopic nature. Their hydrophilic behaviour increases the water demand of mortar mixtures and diminishes their affinity to the matrix, while further moisture-related fibre degradation issues may arise. Additionally, natural fibres seem to be susceptible to degradation caused by exposure to alkaline environmental conditions such as those experienced by cement mortars, restricting their utilisation in the construction industry. Therefore, the current study investigates the potential of fibre modification through treatments that would permanently alter their structure and chemical composition to improve their performance. In this study, wood fibres of black pine and beech species were exposed to mild thermal treatment (140 °C 2 h, under a steam atmosphere), characterised in terms of the physical and chemical properties and incorporated in cement mortars, applying the proportion of 1.5% v/v in the mortar, in order to assess their performance as reinforcement material. The mortars’ workability (at a fresh state) was examined, as well as other physical, hygroscopic, thermal, and mechanical characteristics of the mortars at the ages of 28, 90 and 365 days and weathering performance, by subjecting them to different artificial ageing environments (freeze–thaw cycles or outdoor exposure). The results revealed the beneficial role of the treated fibres in dimensional stability, flexural strength, thermal insulation properties and capillary absorption of the mortar specimens, especially during the ageing process, with the black pine fibres showing the greatest improvement. The hydrothermally treated wood fibres seem to help maintain the integrity of cement mortars under all ageing conditions, proving that they could provide low-cost and eco-friendly mortar enhancement pathways.

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Section: Weathering Performancementioning

confidence: 94%

Section: Weathering Performancementioning

confidence: 99%

Evaluation of Hydrothermally Treated Wood Fibre Performance in Cement Mortars

Kampragkou,

Kamperidou,

Stefanidou

2024

Fibers

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“…Since the porosity distribution is irregular and complex, the use of a simple geometric formulation to describe it is a complete failure to provide insight into porosity. However, it can be studied using fractal theory, i.e., it can be characterized using a fixed non-integer dimension between Euclidean dimensions [34]. The fractal dimension is a quantitative parameter that describes the degree of irregularity of a fractal object.…”

Section: Nuclear Magnetic Resonancementioning

confidence: 99%

Experimental Study on the Microfabrication and Mechanical Properties of Freeze–Thaw Fractured Sandstone under Cyclic Loading and Unloading Effects

Liu,

Cai,

Sheng

et al. 2024

Materials

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A series of freeze–thaw cycling tests, as well as cyclic loading and unloading tests, have been conducted on nodular sandstones to investigate the effect of fatigue loading and freeze–thaw cycling on the damage evolution of fractured sandstones based on damage mechanics theory, the microstructure and sandstone pore fractal theory. The results show that the number of freeze–thaw cycles, the cyclic loading level, the pore distribution and the complex program are important factors affecting the damage evolution of rocks. As the number of freeze–thaw cycles rises, the peak strength, modulus of elasticity, modulus of deformation and damping ratio of the sandstone all declined. Additionally, the modulus of elasticity and deformation increase nonlinearly as the cyclic load level rises. With the rate of increase decreasing, while the dissipation energy due to hysteresis increases gradually and at an increasing rate, and the damping ratio as a whole shows a gradual decrease, with a tendency to increase at a later stage. The NRM (Nuclear Magnetic Resonance) demonstrated that the total porosity and micro-pores of the sandstone increased linearly with the number of freeze–thaw cycles and that the micro-porosity was more sensitive to freeze–thaw, gradually shifting towards meso-pores and macro-pores; simultaneously, the SEM (Scanning Electron Microscope) indicated that the more freeze–thaw cycles there are, the more micro-fractures and holes grow and penetrate each other and the more loose the structure is, with an overall nest-like appearance. To explore the mechanical behavior and mechanism of cracked rock in high-altitude and alpine areas, a damage model under the coupling of freeze–thaw-fatigue loading was established based on the loading and unloading response ratio theory and strain equivalence principle.

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“…This can result in a weaker structure that is unable to support the intended loads or perform as designed. The formation of ice lenses within the concrete during early freezing can lead to increased porosity and permeability [113]. This makes the concrete more susceptible to further freeze-thaw damage as well as other forms of deterioration [83].…”

Section: Early Freezingmentioning

confidence: 99%

An Overview of Smart Materials and Technologies for Concrete Construction in Cold Weather

Nilimaa

Zhaka

2023

Eng

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Cold weather conditions pose significant challenges to the performance and durability of concrete materials, construction processes, and structures. This paper aims to provide a comprehensive overview of the material-related challenges in cold weather concrete construction, including slow setting, reduced curing rate, and slower strength development, as well as frost damage, early freezing, and freeze–thaw actions. Various innovative materials and technologies may be implemented to address these challenges, such as optimizing the concrete mix proportions, chemical admixtures, supplementary cementitious materials, and advanced construction techniques. The paper also examines the impact of weather-related challenges for personnel, equipment, and machinery in cold environments and highlights the importance of effective planning, communication, and management strategies. Results indicate that the successful implementation of appropriate strategies can mitigate the challenges, reduce construction time, and enhance the performance, durability, and sustainability of concrete structures in cold and freezing temperatures. The paper emphasizes the importance of staying updated about the latest advancements and best practices in the field. Future trends include the development of smart and functional concrete materials, advanced manufacturing and construction techniques, integrated design, and optimization of tools, all with a strong focus on sustainability and resilience.

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The Freeze-Thaw Strength Evolution of Fiber-Reinforced Cement Mortar Based on NMR and Fractal Theory: Considering Porosity and Pore Distribution

Cited by 8 publications

References 32 publications

Evaluation of Hydrothermally Treated Wood Fibre Performance in Cement Mortars

Evaluation of Hydrothermally Treated Wood Fibre Performance in Cement Mortars

Experimental Study on the Microfabrication and Mechanical Properties of Freeze–Thaw Fractured Sandstone under Cyclic Loading and Unloading Effects

An Overview of Smart Materials and Technologies for Concrete Construction in Cold Weather

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