Freezing Expansion Research Articles

Effect of colloidal nano silica on the freeze-thaw resistance and air void system of portland cement concrete

The present study investigates the impact of colloidal nano silica (CNS) on the freeze-thaw durability of concrete, with a particular focus on understanding the fundamental mechanism via a systematic analysis of the air void system. Experimental results suggest that the incorporation of CNS increases the total air content of the sample while reducing the average void size. This phenomenon can be attributed to the remarkable capacity of CNS to stabilize air bubbles within the concrete matrix, by a heightened viscosity and lower surface tension of the fresh concrete mixture. The increase in air void chambers facilitates the release of internal stress during freezing expansion, thereby enhancing the freeze-thaw resistance of the concrete. Additionally, the inclusion of CNS results in the formation of a denser cement matrix that improves the water impermeability of the concrete and prevents the ingress of water and other potentially corrosive substances.

Experimental Study of the Multiple Fractalisation of Coal and Rock Failure Subjected to the Coupled Effects of Water, Temperature and Dynamic Loads

The mechanical properties of water-rich coal and rock in a subzero environment are very different from those at room temperature, which causes many unexpected hazards for projects. In this study, coal and rock samples subjected to the coupled effects of water, temperature, and dynamic loads were taken as the research object, and the discussion was shaped around their mechanical properties. The crack evolution trend and different gradient impact velocities were determined using a split-Hopkinson pressure bar (SHPB). Multiple fractals were based on high-speed digital image correlation (HS-DIC) technology and the quality-screening method; the evolution trend of the surface cracks in the crushing process and the distribution characteristics of the specimen fragments after crushing were examined from the perspective of fractals. This provided a powerful supplement to the existing research system on the problem of mining via the freezing method, and it accounted for the shortcomings of the existing research to a certain extent. In this research, the results mainly showed four points: (1) The coal samples were determined to have a wave velocity between 1.68 and 2.01 km/s, while the rock samples were between 2.24 and 2.61 km/s. Under the same conditions, the rock’s resistance to deformation and damage was greater than that of coal. (2) In the saturated state, the plastic strength of the coal and rock samples was greater than that in the dry state, due to the strengthening of their internal stresses caused by the presence of fissure water. (3) With decreasing temperature, the degree of the dynamic compression factor of coal and rock showed a trend of initially increasing, then decreasing, and then increasing. With the increase in the loading rate, the destruction of the coal and rock was more intense, and the destruction process was accelerated. (4) After the saturated coal and rock samples were frozen, their interiors were affected by the dual factors of contraction under the influence of temperature and expansion under the influence of the freezing expansion force. The internal fissures closed or shrank, and the water in the pores turned into ice, leading to an increase in pore volume.

Study of the Load-Bearing Characteristics of Bolts under Asymmetric Freezing Conditions

To investigate the load-bearing characteristics of anchor rods under asymmetric freezing conditions such as those in cold regions and the effect of frost swelling, a model test device was developed using a controlled-temperature environmental box and a hydraulic actuator. Laboratorial pull-out model tests of anchor rods in soil layers were conducted at different moisture contents and freezing temperatures, the changes in anchor rod pull-out force before and after freezing were quantitatively described, load–displacement relationship curves were prepared, and the frost swelling displacement of anchor rods under asymmetric freezing conditions and the stress evolution of surrounding soil were observed and recorded. The shear strength of the anchor–soil interface increased with decreasing temperature, and the ultimate values of the pull-out force at 0, −3 and −7 °C were 4, 17.04 and 18.1 times greater than those at room temperature, respectively, for 10% water content. The pull-out force of the frozen anchor increased with increasing water content. The bolts were displaced by the freezing expansion force. Their lateral displacements at 0, −3 and −7 °C were 2.9, 3.2 and 3.5 mm, respectively, and their vertical displacements were 0.2, 3.5 and 4.3 mm, respectively, for 10% water content. The total displacement increased with increasing moisture content, and the maximum transverse displacements were 3.5, 3.65 and 3.8 mm for 10, 12 and 14% water contents, respectively, and 4.3, 5.1 and 5.5 mm in the vertical direction, respectively. The ultimate pull-out forces after freezing and thawing were 71, 68 and 52% of that before freezing for 10, 12 and 14% water, respectively.

Freezing Pressurized Water into a Standard Cylindrical Ice Sample in a Triaxial Cell

The mechanical characteristics of high-pressure frozen ice are a basis for the design of deep underground frozen walls, the drilling of thick permafrost and ice sheets, and the probing of extraterrestrial ice. The continuous control of the sample stress state from freezing to testing is essential for the experimental study of in situ mechanical response of high-pressure frozen ice. In the context, we developed a preparation technique for freezing pressurized water into a standard cylindrical ice sample in a triaxial cell. Through theoretical analysis, a cylindrical water sample with precise dimensions and strong sealing was fabricated using heat shrinkable tubing, sectional end caps, and an assembly cylinder. A mounting device was designed to insert the water sample into the triaxial cell without deformation. In order to deal with the lateral surface irregular of the resulting ice sample caused by freezing expansion, we proposed a pressurization method in which the volume of the confining medium is controlled to restrict the radial deformation of the sample, and the axial pressure on the sample is kept constant; thus, the freezing expansion will develop along the height direction through releasing the expansion pressure. Based on the analysis of sample deformation and finite element numerical simulations, the control method of the temperature fields of the sample and the confining medium was obtained, and the standard cylindrical ice sample which satisfies the geometric accuracy requirements was produced. The comparison of ice samples frozen by different freezing methods showed that the control of the confining medium mean temperature and the sample unidirectional freezing is necessary to improve the dimensional precision of the ice sample.

Evaluation of the impact of freeze-thaw cycles on pore structure characteristics of black soil using X-ray computed tomography

Freeze-thaw cycles extensively and intensely occur in northeast China and generate significant effects on soil pore structure. The objective of this study was to obtain three-dimensional (3D) images of soil pore structures utilizing industrial X-ray microtomography and to apply image analysis techniques to visually and quantitatively evaluate the impact of the freeze-thaw effect on pore characteristics of black soil. The soil samples were subjected to zero (T0), one (T1), five (T5), ten (T10), fifteen (T15), and twenty (T20) freeze-thaw cycles and were then scanned at a 25-μm resolution to construct pore-throat network images. The results showed that the freeze-thaw effect increased the porosity of the soil 3D microstructure and that the pore-throat networks became increasingly complex with a greater number of freeze-thaw cycles. The total porosity and macroporosity increased significantly with an increase in the number of freeze-thaw cycles (p < 0.05). The soil in the T20 treatment displayed the greatest total porosity and macroporosity, which were 247.8 and 251.1 % greater, respectively, than in the T0 treatment. In freeze-thaw processes, contraction of the solid phase is induced by thawing of ice crystals but is insufficient to counteract the displacement induced by the freezing expansion of ice crystals. Macroporosity contributes to most of the increase in total porosity between each treatment. The numbers of pore throats and paths were significantly and positively correlated (p < 0.05) with the number of macropores. The freeze-thaw effect mainly affected those pores with greater effective diameters, which may include more branch paths and throats. The findings of this study can help to improve the understanding of soil dynamic processes under freeze-thaw cycles and further enable the utilization of pore morphology in monitoring the quality of soil structure.

Evaluation and improvement on the freeze-thaw durability performance of the polyurethane stabilized Pisha sandstone for water and soil conservation

Stabilization of the loose and fragile Pisha with the hydrophilic polyurethane material has been proved to be a time and cost-efficient protocol for the conservation of soil and water. However, the undesirable durability performance of the original W-OH binder material deteriorate its long-term conservation ability, especially under the freeze-thaw cycles. This study aims to improve the freeze-thaw durability performance of the W-OH composites through mixture design optimization and material modification. This study first investigates the correlation between the freeze-thaw resistance of the W-OH/Pisha sandstone composites and the concentration of the applied W-OH solution. The test results indicated both the compressive strength and elastic modulus of the W-OH based composites would decrease with freeze-thaw cycles and the samples prepared with higher concentration W-OH solution own better freeze-thaw resistance. Meanwhile, the elastic modulus of the W-OH composites decreased almost linearly with the freeze-thaw cycles, which is in accordance with the linear increase of the porosity of samples determined with the ultra-depth-of-field microscope. Based on these mechanism analyses, the modification of the W-OH material was further conducted with the Ethylene-vinyl acetate (EVA) and air entrainer. The compressive strength test results indicate both the added EVA can enhance the freeze-thaw durability of the W-OH composites, which can be caused by the improved cohesion strength of the W-OH binder due to enhanced density. Similarly, the freeze-thaw durability of the W-OH composites was also enhanced with added air entrainer, which provided extra space for the freezing expansion. The research results of this study can enhance the freeze-thaw durability of the stabilized Pisha sandstone and its long-term conservation ability on soil and water.

Quantifying expansion effects induced by FreezeThaw cycles in partially water saturated bituminous mix : Laboratory Experiments

Contraction/expansion effects induced by freeze-thaw cycles are thought to be at the origin of important and sudden deteriorations of pavement surface course, observed on some road sections in North-East of France. Therefore following these events and observations, it was decided to investigate in laboratory the phenomenon of freeze-thaw on partially water saturated bituminous materials specimen. This article presents some aspects of this beginning research work. We report an experimental investigation on the effect of the freezing-thaw cycles of bituminous materials. Some specimens are subjected to laboratory freeze-thaw cycles under a freezing rate without moisture change with the environment. In addition to basic mechanical properties and pore distribution, the measurement is also performed for freezing expansion of material of the specimen in each cycle. From these results, it is observed that the freezing expansion can be measured for high degree of saturation of the material. The results indicate also that the specimens experiment significant swelling at the beginning of the freezing periods. It is believed that the phenomenon could be detrimental to pavements, especially in the case of differential horizontal strains appearing within the structure layers, due to different swelling conditions depending on the materials and their moisture content.

점토바닥벽돌의 품질 및 시공기준 연구

최근 들어 도심지 보도 또는 아파트 단지내 도로 등에 시공되는 보도블록에 대한 소비자의 눈높이가 높아짐에 따라 과거에는 콘크리트 블록 일색이었던 보도포장 재료가 점토바닥벽돌, 천연석 또는 나무 등으로 다양화 고급화되고 있다. 그 중 특히 사람에게 친환경 친인간적인 점토바닥벽돌의 판매량은 해마다 두 자리수 이상의 성장률을 보일만큼 수요자가 다양하고 많아지고 있으나 시공 후 단시간 내에 '모서리 깨짐', '동결 파손', '휨파괴' 및 '줄눈 벌어짐' 등의 파손이 빈번하게 발생되고 있어 내구성 문제가 지적되고 있다. 점토바닥벽돌은 요업제품의 특성상 벽돌끼리 부딪힐 경우에는 쉽게 깨지는 특성을 가지고 있으며, 물을 쉽게 흡수하는 성질이 있어 동결로 인한 부피 팽창 파손에 비교적 취약할 뿐만 아니라 생산설비와 공정관리 등 생산과정의 미세한 차이에 따라 제품의 강도 또는 흡수율 등 물성에 대한 편차가 크게 발생한다. 그리하여 엄격한 품질관리 기준에 따라 생산과 시공을 하지 않을 경우, 제품에 하자가 발생하여 유지보수에 많은 비용이 소요된다. 본 연구에서는 점토바닥벽돌 포장에서 흔히 발생하는 파손 증상을 유형별로 분류하여 원인을 분석하였으며, 필요시 압축 강도 및 흡수율 시험 등을 통하여 벽돌의 생산, 시공 및 품질관리 기준 등 광범위한 부분에 걸쳐 해결방안을 제시하였다. As the customer's interest for sidewalk block in the street or apartment complex is increasing, the materials of block which had been a concrete block exclusively are varied to clay paver, native rock and wood etc. Especially, the sales volume of clay paver which is environment-friendly and ergonomic is dramatically increasing every year with two digits growth rate, however, many problems like "Edge Cracking" "Freezing Breakage" "Bending Breakage" "Joint Gap" are happening frequently within a couple of hours after installation due to the durabilities. Because of the characteristics of Ceramic products, clay pavers are very easy to be broken when they are bumped against each other. In addition, they are relatively fragile by a freezing expansion breakage when exposed to water due to hydrophilic property as well as the intensity and absorptance of the products are varied with small difference from the production process such as production equipment and process control. Therefore, it costs a lot of money to repair the breakdown unless production and installation is carried out according to the strict criteria of the quality control. In this study, the symptoms of breakdown frequently happened in clay paver are classified by each type and finally the solution for this problem in the production of brick, installation and criteria of quality control through compressive strength and absorptance test is suggested.

Quantifying Expansion Effects Induced by Freeze-Thaw Cycles in Partially Water Saturated Bituminous Mix

ABSTRACT Contraction/expansion effects induced by freeze-thaw cycles are thought to be at the origin of important and sudden deteriorations of pavement surface course, observed on some road sections in North-East of France. Therefore following these events and observations, it was decided to investigate in laboratory the phenomenon of freeze-thaw on partially water saturated bituminous materials specimen. This article presents some aspects of this beginning research work. We report an experimental investigation on the effect of the freezing-thaw cycles of bituminous materials. Some specimens are subjected to laboratory freeze-thaw cycles under a freezing rate without moisture change with the environment. In addition to basic mechanical properties and pore distribution, the measurement is also performed for freezing expansion of material of the specimen in each cycle. From these results, it is observed that the freezing expansion can be measured for high degree of saturation of the material. The results indicate also that the specimens experiment significant swelling at the beginning of the freezing periods. It is believed that the phenomenon could be detrimental to pavements, especially in the case of differential horizontal strains appearing within the structure layers, due to different swelling conditions depending on the materials and their moisture content.

Influence of freezing rate on cryo-damage of cementitious material

We report an experimental investigation on the impact of the freezing rate on the cryo-deformation and cryo-damage of cementitious materials. Saturated, dried and air-entrained mortar specimens are subjected to laboratory freeze-thaw cycles under three freezing rates without moisture exchange with the environment. In addition to basic mechanical properties and pore distribution, the measurement is also effectuated for freezing expansion, residual deformation of the specimens in each cycle. From the results it is observed that a high freezing rate does augment the freezing expansion of material while the cryo-damage is more important for a low freezing rate. Accordingly, both the freezing rate and freezing duration should be taken into account for the cyro-damage extent of cementitious materials.

Numerical investigations and engineering applications on freezing expansion of soil restrained two-phase closed thermosyphons

A numerical simulation has been carried out to describe the coupled heat transfer of water-saturated soil with a two-phase closed thermosyphon. This problem is characterized by the phase change occurring in the water-saturated soil, moving freezing front and heat transfer of a two-phase closed thermosyphon. According to the governing equations in the porous media and heat transfer characteristics of the two-phase closed thermosyphon, the temperature distributions in the water-saturated soil and the moving freezing front are solved numerically by the finite-difference method. The predictions of the present study are well agreed with the measured data. The mechanism of the freezing expansion restrained by the two-phase closed thermosyphon is exposed, based on which the effective radius can be determined for engineering applications.

A Thermodynamic Study of Liquid Transportation in Freezing Porous Media.

A dynamic equation of state at the solid-liquid interface for a lipuid-saturated solid-liquid-porous system has been derived from a thermodynamic study modeling simultaneous heat and mass transfer through purous media from the liquid supply front to the solid-liquid interface. This is the first step in building a mathematical model which macroscopically describes a freezing expansion phenomenon with mass transfer in saturated porous media. It has been revealed that the derived dynamic equation of state generalizes the so-called generalized Clausius-Clapeyron equation, i.e.the static equation of state for porous media without mass transfer, and that mechanical energy produced at the solid-liquid interface is equal to mechanical energy dissipation due to the mass transfer.

A Thermodynamic Study of Liquid Transortation in Freezing Porous Media.

A dynamic equation of state at the interface for a liquid-saturated solid-liquid porous system has been derived from a thermodynamic study modeling simultaneous heat and mass transfer through porous media from the liquid supply front to the interface, as the very first step in building a mathematical model which may macroscopically describe a freezing expansion phenomenon with mass transfer in saturated porous media. It has been revealed that the derived dynamic equation of state generalizes the so-called generalized Clausius-Clapeyron equation, i.e. the static equation of state for porous media without mass transfer, and that mechanical energy produced at the interface is equal to mechanical energy dissipation due to the mass transfer.

Mechanisms of rock breakdown by frost action: An experimental approach

Freezing behavior and frost shattering of rocks were studied in the laboratory. Rates of frost shattering were determined for 47 different samples of saturated rocks partially immersed in water by a decreasing rate of the longitudinal wave velocity during freeze-thaw cycles. The ratio of surface area per unit volume to tensile strength gives a good estimation of the frost shattering rate. This indicates that water migration caused by adsorptive suction participates in the frost shattering, as well as the 9% volumetric expansion. Frost shattering occurred in porous rocks despite the lower saturation level than the theoretical value derived from the volumetric expansion theory. Furthermore, the open system was much more effective in frost shattering than the closed system was. Such moisture effects also demonstrate the large role of water migration in frost shattering. The linear strain of some saturated rocks during a freeze-thaw cycle was measured with foil strain gauges. Immersion in water increased the freezing expansion of tuffs, although it affected the strain of a shale and an andesite only little. Low cooling rates resulted in small freezing expansion of rocks placed under the closed system because of creep of pore ice. These results suggest that the freezing expansion of a rock consists of three components: two positive strains due to the 9% volumetric expansion of water, and water migration controlled by adsorptive suction, and a negative strain due to creep of ice. The frost shattering of the tuffs would be primarily controlled by the water migration, and that of the shale and andesite is probably caused by the volumetric expansion. The relative contribution of the two processes on frost shattering may depend on the surface area per unit volume of the rocks.

Pore Water Pressure and Consolidation in Unfrozen Soil near the Freezing Front

When the soft soil freezes accompanying with the water suction, the effective stress increases with the lowering of pore water pressure that takes place near the freezing front, and thereby the unfrozen soil adjacent to it is subjected to a fairly strong dewatering consolidation. In this paper pore water pressure distribution in front of unidirectional freezing front penetrating at a constant rate is analyzed theoretically, and it is found that the lowering of pore water pressure is larger than expected. Therefore the lowering of the pressure may explain a soft soil subsidence after thawing and sludge dewatering by freezing. Influence region of dewatering consolidation, δs, is given by Cυ/U, and transitional time attaining to a steady state, τt, is given by A·Cυ/U2. Here Cυ is coefficient of consolidation, U is frost penetration rate and A is a positive constant.In the case of soil which is relatively low in the degree of consolidation, the freezing expansion and dewatering consolidation take place simultaneously, and at far from δs in unfrozen soil the result of their mutually subtracted effect is observed as the amount of frost heave. Then, frost heave ratio, ξ, is given approximately by ξ0+nfΓ. Here ξ0is a characteristic constant of the soil, nf is free water content of soil at freezing temperature andΓ is nondimensional volumetric expansion ratio of water at freezing ≅ 0. 09.

The expressible fluid of fish fillets. IX.—other types of cell damage caused by freezing

AbstractCell damage occurring at a freezing time of 25 minutes ( ‘peak A ’) was investigated, and found to be the result of the mechanical action during freezing expansion of ice crystals of a certain critical size growing within the cell. Supercooling, followed by a sudden rapid growth of ice, at the onset of freezing was found not to damage the cells unduly. Evidence was presented to show that the expressed fluid of cod fillets originates near the cut surface only, and does not come from the deeper layers.