Stress-Strain Model for Concrete Under Compressive Stress that Has Undergone Freeze-Thaw Deterioration
- This requires strict quality control measures, including periodic testing and characterization of bentonite batches, to ensure consistency and reliability in engineering applications (Kiviranta and Kumpulainen, 2011; Svensson et al., 2017; Magnus et al., 2020).
- Dagli et al. (2018) investigated the role of suction in water migration to the frost front.
- Hence, a greater increase in water retention capacity was observed for BB-amended CL soil compared to biochar-amended SM soil in both confined and unconfined conditions.
- The utmost decrease in UCS value was observed during the initial F-T cycle, while it was found to be decreased at higher cycles for both soil types.
- Soil movement below the concrete leads to settling and sinking, creating uneven and potentially dangerous surfaces.
Under uniaxial tensile stress, internal pores and fractures within the rock tend to open, in contrast to that in uniaxial compressive stress state under which they are more likely to close. In natural rock formations, the gravitational stress causes pore water to infiltrate downward. The freeze–thaw process exacerbates the longitudinal expansion of rock fractures, thereby intensifying the longitudinal damage due to frost heave stress.
Low temperature thermal analysis
Extensive research on frost-heaving has been conducted since the early 1990s till date. Taber (1930) and Taber (1929) explored the frost-heaving mechanisms such as the growth of ice lenses in soil. Mu and Ladanyi, (1987) developed models that integrated stress-strain behavior, heat, and mass transport to estimate frost heave.
Concrete Compaction Tools for Effective Concrete Consolidation
This infiltration is further heightened by wetting and drying cycles, which can occur naturally or as a result of environmental conditions such as temperature and water table fluctuations. At higher temperatures, water travels at a faster rate along with sulfate ions, which accelerates the chemical reaction between the sulfate and the hydration products of the cement (Ikumi and Segura, 2019; Chen et al., 2020; Zhu et al., 2023). This acceleration causes swellable compounds to form more quickly and increases the rate of deterioration. This reaction results in the formation of expansive compounds such as gypsum and ettringite (Ikumi and Segura, 2019; Chen et al., 2020). These compounds exert pressure within the concrete matrix, causing internal cracking, expansion, and ultimately deterioration of the concrete structure.
Effects of Freezing and Thawing on the Consolidation Settlement of Soils
Particularly, protein Aggregation is an issue that can be detrimental to data quality. Determining protein stability and quality first can therefore save both time and money e.g. in subsequent screening campaigns. NanoTemper’s instrument Tycho NT.6 (see Tycho NT.6 on nanotempertech.com) can be used to determine optimal handling conditions by quantifying the fraction of unfolded protein in a sample within seconds.
Wrapping It Up With a Bow: The Gift of Protected Concrete
The specimens exposed to freeze-thaw conditions were placed inside a digital freezing cabinet set at – 10 °C for 12 h, followed by a thawing phase at + 30 °C for an additional 12 h. ProGorki Pools of this freezing and thawing cycle was referred to as one cycle, and this procedure was repeated up to a total of 8 cycles. Zanbak and Arthur (1986) discussed the mechanism of hydration expansion and deformation of anhydrite rock, and the study showed that the molar volume of anhydrite increases after water absorption, and the volume expansion could be 62.6%. Madsen and Müller-Vonmoos, (1989) carried out theoretical and experimental studies on the microscopic scale from the perspective of mineralogy on the interaction between clay particles, anhydrite, and gypsum crystal. Kaiser (1975) studied the growth and expansion of ettringite and anhydrite crystals in solution, and believed that with the change of thermal equilibrium and hydrodynamics, the anhydrite expansion curve showed a logarithmic curve growth form.
Soil temperature changes during the freeze-thaw period and the carry-over effects of freeze-thaw on soil nutrients
The displacement-based loading mode was utilized at a constant rate of 0.5 mm/min. Test data was acquired at an interval of 1 s, which well facilitates the analysis of peak strength and stress–strain curves of the granite after freeze–thaw cycles. Rocks are normally in a compressed state, and rock damage is commonly understood to be compression-shear failure, in which shear force primarily causes rock grains to slide over the damaged surface40. Nevertheless, damage appears differently in rocks affected by freeze–thaw cycles, especially those that are 50 cm or less below the surface41,42. In some high-locality landslides on the Eastern Tibetan Plateau, cracks extending up to 200 m are often observed along the edges, indicating a combination of shear and tensile failure. Identifying the failure state becomes particularly challenging under the influence of repeated freeze–thaw cycles and complex stress conditions43.
- The percentage increase in UCS was observed to be 2.69% and 10.51% with the addition of 1% and 2% BB in CL soil, respectively.
- While some water moves back toward the exterior due to forces like evaporation, thermal vapor drive, or gravity, a portion of it often remains trapped in small internal pockets.
- If the tensile stress exceeds the ultimate tensile strength of the concrete, microcracks begin to generate (Zeng et al., 2010).
- No significant changes in the purity of the mAb-1 has been observed by chromatographic and electrophoretic methods of SE-HPLC, CE-SDS, and peptide mapping over time when stored at the intended long-term storage condition.
The compressive strength of both CL and SM soils decreased with increasing freeze-thaw cycles, with 2% BB-amended soils showing strength reductions of 29.32–40.22% for CL and 28.52–43.76% for SM soils from the first to the third freeze-thaw cycle. The water retention of both soils increased with BB addition, with CL soil showing a greater increase in water retention compared to SM soil under both unconfined and confined conditions. In addition to BB, the muscovite mineral and higher SSA of CL soil also contributed to the improved water retention. The GWC decreased at all suction points under confined conditions for both biochar-amended soils. Microscopic analysis revealed that the reduction in GWC was due to a decrease in pore spaces under confined conditions in both soils. The results also indicate that the increase in strength was more significant in BB-amended CL soil than in non-amended soil with the curing period. In contrast, the strength of both biochar-amended soils (BAS) decreased with the increase in freeze-thaw cycles, due to the expansion and contraction of ice within the specimen. The porous and hydrophilic nature of biochar (BB) increased the water retention capacity of both soils, with a more significant improvement observed in CL soil compared to SM soil, under both compacted and slurry conditions. Specimen compaction significantly decreased the gravimetric water content at the permanent wilting point in both soils. The uniaxial tensile strength of the granite sample decreases nonlinearly with freeze–thaw cycles, like the uniaxial compressive strength while the decrement in uniaxial tensile strength is rather small.
1 Pore characteristics of soil aggregates
The use of biochar in landfill covers has the potential to reduce methane emissions by up to 80% while simultaneously enhancing leachate quality through the reduction of heavy metals and other pollutants13. The use of biochar as soil amendment enhances water-retention capacity and influences soil tensile strength14. The moisture retention capabilities of biochar potentially establish a moisture content equilibrium for a long duration15. The prolonged moisture equilibrium of biochar-amended soil (BAS) affects strength, which is tricky and vital for geo-environmental engineering projects. This equilibrium can impact soil strength by optimizing compaction efficiency and reducing potential moisture-related degradation, thereby enhancing the overall strength. In addition, surface characteristics of biochar can evolve during the curing period, leading to chemical interactions with soil components16.
Variation of GWC with suctions in unconfined and confined conditions
All concentration deviations relative to the concentration after the first freeze/ thaw cycle were less than 5 % for -20 °C and -80 °C cycling with both isolation methods. The average percentage differences of liquid nitrogen samples were higher, and the MagNA isolation method showed significant differences. The repeating freeze/ thaw up to 100 cycles (through -20 °C and -80 °C, respectively) did not significantly influence the integrity, concentration, or purity of genomic DNA, suggesting that storage of samples in high-volume pools without multiple aliquoting is possible. Storage in a freezer seems to be the most suitable way of long-term DNA preservation, because liquid nitrogen storage leads to formation of DNA clumps. Soil temperature is also a key environmental factor influencing plant dormancy and sprouting38, however, it is not the main reason for differences in sprouting between treatments in this study.
