Freeze-thaw Cycle Test Research Articles

Damage mechanisms of ultra-high-performance concrete under freeze–thaw cycling in salt solution considering the effect of rehydration

Accelerated freeze–thaw cycling tests in 5.0 wt% NaCl solutions were performed to better understand the durability of ultra-high-performance concrete (UHPC) with a 0.2 water-binder ratio under freeze–thaw cycles in a salt environment (as experienced by concrete used in harsh marine environments). The bound water and pore structure were evaluated before and after cycling. Unhydrated cement rehydrated during the freeze–thaw cycling and hydration products repaired small pores (<100 nm). The ice-formation expansion rates of 0–10 wt% NaCl solutions were determined. The damage mechanisms were discussed considering the supercooling effect and salt concentration. The conclusions of this study are valid for specific properties of UHPC under freeze–thaw cycling in salt solution.

Laboratory Evaluation on Performance of Eco-Friendly Basalt Fiber and Diatomite Compound Modified Asphalt Mixture.

This study proposed an asphalt mixture modified by basalt fiber and diatomite. Performance of diatomite modified asphalt mixture (DAM), basalt fiber modified asphalt mixture (BFAM), diatomite and basalt fiber compound modified asphalt mixture (DBFAM), and control asphalt mixture (AM) were investigated by experimental methods. The wheel tracking test, low-temperature indirect tensile test, moisture susceptibility test, fatigue test and freeze–thaw cycles test of four kinds of asphalt mixtures were carried out. The results show that the addition of basalt fiber and diatomite can improve the pavement performance. Diatomite has a significant effect on the high temperature stability, moisture susceptibility and resistance to moisture and frost damage under freeze–thaw cycles of asphalt mixture. Basalt fiber has a significant effect on low-temperature cracking resistance of asphalt mixture. Composed modified asphalt mixture has obvious advantages on performance compared to the control asphalt mixture. It will provide a reference for the design of asphalt mixture in seasonal frozen regions.

Study on Strength Characteristics of Solidified Contaminated Soil under Freeze-Thaw Cycle Conditions

Cement solidification/stabilization is a commonly used method for the remediation of contaminated soils. The stability characteristics of solidified/stabilized contaminated soils under freeze-thaw cycle are very important. A series of tests, which include unconfined compressive strength tests, freeze-thaw cycle tests, and scanning electron microscopy (SEM) tests, are performed to study the variation law of strength characteristics and microstructure. It aims at revealing the microcosmic mechanism of solidified/stabilized Pb2+ contaminated soils with cement under freeze-thaw cycle. The results show that the unconfined compressive strength of the contaminated soils significantly improved with the increase of the cement content. The unconfined compressive strength of stabilized contaminated soils first increases with the increase of times of freeze-thaw cycle, and after reaching the peak, it decreases with the increase of times of freeze-thaw cycle. The results of the scanning electron microscopy tests are consistent with those of the unconfined compressive strength tests. This paper also reveals the microcosmic mechanism of the changes in engineering of the stabilized contaminated soils under freeze-thaw cycle.

Laboratory Investigation on the Use of Bamboo Fiber in Asphalt Mixtures for Enhanced Performance

This study evaluated the use of bamboo fiber, which is a new member in the natural fiber category, in dense-grade (DG) and stone matrix asphalt (SMA) mixtures for enhanced performance. Bamboo fiber has high tensile strength in fiber direction, and it also has rough surface texture comparable to that of a commonly used lignin fiber. Moreover, bamboo fiber exhibits sufficient thermal stability, which is a typical concern of plant-based materials. Marshall mix design procedure was followed to select optimum asphalt binder contents of DG and SMA mixtures that contain various amounts of bamboo fiber. Effects of bamboo fiber on mixture moisture susceptibility, rutting and low-temperature cracking performance were evaluated using the immersion Marshall, freeze-thaw cycling tests, wheel tracking test and three-point bending beam test, respectively. Testing results showed the use of bamboo fiber effectively enhanced the above-mentioned mixture performance. In addition, the optimum bamboo fiber contents for DG and SMA mixtures were found to be 0.2–0.3% and 0.4% (by weight of mixture). Finally, mixtures with bamboo fiber exhibited equivalent or better performance than the same mixtures with polyester fiber and lignin fiber, indicating the applicability of bamboo fiber in asphalt mixtures.

Evaluation of the bond strength of a novel concrete for rapid patch repair of pavements

Patch repair is an important category in the repair or restoration of pavements. The effectiveness of the repair largely depends on the bond strength between the repair material and the concrete substrate. In the present work, surface roughness, bonding agents and curing age of the repair materials have been taken into consideration to evaluate the applicability and serviceability of a novel rapid repair material for concrete pavement. A three-factor and four-level orthogonal experiment was designed for systematic investigation. The bond strength of the combined specimens was measured using splitting tensile test and direct shear test. It is found that the splitting tensile strength varied from 1.21 MPa to 2.43 MPa and the direct shear strength varied from 2.84 MPa to 5.92 MPa and the bond strength has a good correlation with surface roughness and curing age. Different failure modes and the shear-slip characteristics were analyzed to understand the actual bond performance of combined specimens. It can be concluded that the slip distance of high surface roughness concrete was almost three times that of low surface roughness. In addition, the freeze-thaw cycle test of the combined specimen was conducted to validate the compatibility of the designed repair material with the concrete substrate. It is found that the he splitting tensile strength and direct shear strength of high surface roughness specimens reduced to 74.5% and 66.3% of its original bond strength after 100 times of freeze-thaw cycles, respectively. The rapid repair material studied in this study can act as a promising alternative for rapid patch repair of concrete pavements.

Experimental investigations on the effects of ambient freeze-thaw cycling on dynamic properties and rock pore structure deterioration of sandstone

The issue of rock pore structure deterioration and dynamical mechanical properties has drawn much attention in recent years in the rock engineering community. In this study, a series of 140 freeze-thaw cycling tests are conducted on sandstone samples. The sandstone pore structure after freeze-thaw cycles was detected by Nuclear Magnetic Resonance (NMR), and the dynamic load test was carried out by Split Hopkinson Pressure Bar system (SHPB). The results are: with the increase of freeze-thaw cycles, the saturated mass and porosity of sandstone increase, the dynamic peak stress of sandstone decreases; while the peak strain and total strain increase gradually, and the macroscopic damages of rocks increase. The results of T2 distribution and pore size changes are that the pore sizes of sandstones increase, especially that of micro-pores and macro-pores increase obviously after 140 freeze-thaw cycles. Under the effect of freeze-thaw cycles, the sandstone pores become connected with each other, some of the micro-pores and mini-pores are changed into meso-pores and macro-pores. The number of marco-pores increases evidently, and the largest increase is 197.23%. The rock pore structures have changed, which would lead to the change of mechanic properties. As the number of freeze-thaw cycles increases, the rock dynamical peak stress gradually decreases and the peak strain and the overall strain increase gradually.

Coupling effect of salt freeze-thaw cycles and cyclic loading on performance degradation of carbon nanofiber mortar

This paper aims to investigate the coupling effect of salt freeze-thaw cycles and cyclic loading on weight loss, relative dynamic elasticity modulus and electrical resistance degradation of carbon nanofiber mortar. Three types of salt solutions with NaCl concentrations of 0%, 1.5% and 3.0% were adopted and two freeze-thaw temperatures cycles were carried out at −10 °C ~ 10 °C and −20 °C ~ 20 °C respectively. Cement mortars with water to cement (w/c) ratios of 0.5, 0.45, 0.4 and 0.35 were prepared by incorporating carbon nanofibers (CNFs) with 2.25% of cement volume. On the other hand, cyclic loading was applied to selected specimens before the freeze-thaw cycle test. Experimental results show that all specimens behaved little mass loss after exposure to the salt freeze-thaw cycles under temperature of −10 °C ~ 10 °C and a significant mass loss was induced by the freeze-thaw cycles in 1.5% NaCl and 3.0% NaCl solutions with temperature of −20 °C ~ 20 °C. On the other hand, no visible difference can be detected for the electrical resistance variation and the relative dynamic elasticity modulus under the two freeze-thaw temperatures for every salt solution. The cyclic loading treatment had an accelerating degradation of cement mortar induced by the salt freeze-thaw cycles. The electrical resistance increase of carbon nanofiber mortar reveals a similar tendency to the relative dynamic elasticity modulus loss. Therefore, carbon nanofiber mortar behaves a potential self-sensing performance for salt freeze-thaw cycles induced damage.

Road Performance Prediction Model of AC-25 Asphalt Mixture

25 groups of AC-25 asphalt mixture are designed by referencing the orthogonal design method, the high temperature rutting and freeze-thaw cycle test are carried out, the related model of the fractal dimension and the road performance evaluation index including dynamic stability and freeze-thaw cycle dynamic stability ratio is established by using fractal theory. The high temperature stability and water stability performance of AC-25 asphalt mixture can be predicted according to the gradation designed. This can reduce the test workload, improve work efficiency, and offer the reference for engineering design.

Sensitivity Analysis of Factors Affecting Time-Dependent Slope Stability under Freeze-Thaw Cycles

With open-pit mines excavated, the slopes will be exposed to the natural environment for a long time. Affected by factors like temperature, seepage, mining, freeze-thaw, etc., slope structural integrity and strength will gradually decline as slope exposure time extends. Besides, the development of defect structure within the rocks is closely correlated with time. In this paper, freeze-thaw cycle tests were conducted on the saturated sandstones collected from a certain open-pit mine. According to the test results, the mass density and longitudinal wave velocity gradually increased with more times of freeze-thaw cycles while mechanical properties such as internal friction angle, cohesion, elastic modulus, and uniaxial compressive strength decreased instead. The constitutive model of saturated rock deterioration was established by taking the volume of phase transition of water in microcracks as a variable. Based on the tests results and theoretical analysis, the sensitivity of the factors affecting slope stability under freeze-thaw damage was studied by Control Variable Method (CVM) and Orthogonal Design Method (ODM). It was determined that the internal friction angle and cohesion had a highly significant effect on the test results, while the mass density had a significant effect. The conclusions may play a certain role in guiding slope construction and protection.

Effect of Different Media Aqueous Solution on Road Performance of Asphalt Mixtures

Servicing in the natural environment, asphalt pavement is often exposed to the various aqueous solution, however, the effect of different media aqueous solution on road performance of asphalt mixtures remains ambiguous. In this study, the influences of water, acid, alkali and salt solution on volume of air voids (VV), tensile strength rate (TSR), low temperature performance of 70# asphalt mixtures and SBS modified asphalt mixtures were investigated through freeze-thaw cycles test, void ratio test, Lottman test and Three-point Bending Fracture (TBF) test. The results indicated that freeze–thaw cycles influenced the road performance of asphalt mixtures significantly, increased the air void of asphalt mixtures, and reduced tensile strength ratio and failure strain of asphalt mixtures. Compared with the distilled water, the damage of acid, alkali and salt solution on the road performances of asphalt mixtures were more serious, especially alkali solution to tensile strength rate and failure strains in low temperature, and salt solution to VV. The moisture corrosion resistance of SBS modified asphalt mixtures is better than that of 70# asphalt mixtures.

Effects of Imposed Damage on the Capillary Water Absorption of Recycled Aggregate Concrete

Capillary water absorption of concrete is closely related to its pore structure, permeability, and durability. This paper intensively investigates the effects of imposed damage, including freeze‐thaw damage and loading damage, on the capillary water absorption of recycled aggregate concrete (RAC). Freeze‐thaw cycle test, loading test, and the experiment of capillary water absorption were carried out, respectively. The results demonstrate that the addition of recycled coarse aggregate (RCA) results in the increase in the capillary absorption behavior of RAC without imposed damage, and there exists a linear correlation between the behaviors of capillary water absorption and chloride penetration of RAC. The imposed freeze‐thaw damage or load damage of RAC boosts with the increase of RCA replacement percentages after suffering the same freeze‐thaw cycles or loading level. The imposed freeze‐thaw damage and load damage further lead to the increase in the capillary water absorption of RAC, and the capillary absorption coefficient of RAC increases linearly with the increased RCA replacement percentages, after suffering the same freeze‐thaw cycles or loading level. Furthermore, capillary absorption coefficient increases linearly with the growth of imposed freeze‐thaw damage or load damage degree, which can be used to estimate the capillary absorption behavior of RAC exposed to the extreme environment.

REPEATED FREEZE-THAW CYCLES BUT NOT SHORT-TERM STORAGE OF FECAL EXTRACTS AT AMBIENT TEMPERATURE INFLUENCE THE STABILITY OF STEROID METABOLITE LEVELS IN CRESTED MACAQUES

The objective of this study was to examine the effects of repeated freeze-thaw cycles and short-term storage of fecal extracts at ambient temperature on the stability of fecal glucocorticoid (fGCM) and estrogen metabolite (fEM) levels from crested macaques.In total 100 aliquots of fecal extracts from fecal samples collected from female crested macaques (Macaca nigra) living at the Tangkoko-Batuangus Nature Reserve, North Sulawesi were used. We performed two different experiments: (1) An experiment to investigate if levels of fGCM and fEM measured from fecal extracts that were exposed to two, four, six and eight repeated freeze-thaw cycles (test groups) differ to control samples (i.e. fecal extracts always stored frozen); (2) An experiment to evaluate whether storing fecal extracts at ambient temperature for two, four, six, and eight days (test groups)affects the levels of fGCM and fEM compared to the control group (i.e. fecal extracts frozen immediately).Results showed that hormone levels were significantly increased (P&lt;0.05) after four freeze-thaw cycles for fGCM and after eight freeze-thaw cycles for fEM. By contrast, there was no significant difference (P&gt;0.05) in levels of fGCM and fEM between the test groups and the control group in fecal extracts stored at ambient temperature. In conclusion, our data show that more than two and six repeated freeze-thaw cycles should be avoided when measuring fGCM and fEM in crested macaque fecal extracts, respectively. We also demonstrate that storing fecal extracts at ambient temperature is possible for at least 8 days without taking a risk of affecting the stability of fGCM and fEM levels.

Experimental Evaluation of Thermal Performance and Durability of Thermally-Enhanced Concretes

The thermal performance and durability of the thermally-enhanced concrete with various insulating materials were evaluated through a series of tests. Three types of insulating materials—diatomite powder, hollow micro-spheres, and a micro-foam agent—were used for both normalweight aggregate concrete (NWAC) and lightweight aggregate concrete (LWAC). The thermal conductivity was measured by two different test methods: quick thermal conductivity meter (QTM) and guarded hot wire (GHW) methods. Then, the results were compared with each other. All insulating materials used in this study proved their ability to reduce the thermal conductivity. Additionally, it can be found that the trend of a decrease in air-dry density is similar to that of thermal conductivity of thermally-enhanced concrete. Additional thermal transmission tests with seven large-scale specimens were conducted by using the calibrated hot box (CHB). However, from this tests, it was seen that thermal transmission reduction for tested specimens were not large compared to the thermal conductivity reduction measured by QTM and GHW, due to multiple heat transfer. To examine the durability of thermally-enhanced concretes, accelerated carbonation and freeze-thaw cycle tests were conducted. From the results, it can be found that the thermally-enhanced concrete shows good freeze-thaw resistance. However, the carbonation rates of the concretes increased rapidly and additional methods to improve the carbonation resistance should be considered.

Formulasi Pasta Gigi Gel Ekstrak Etanol Bawang Dayak (Eleutherine bulbosa (Mill.) Urb.)

Karies gigi adalah suatu kerusakan gigi yang dimulai dari permukaan dan berkembang ke arah dalam pada gigi, diawali dengan proses demineralisasi gigi. Karies gigi biasanya disebabkan oleh bakteri streptococcus mutans. Bawang dayak (Eleutherine bulbosa (Mill.) Urb) dapat menghambat pertumbuhan bakteri karena mengandung metabolit sekunder seperti flavonoid, fenol, triterpenoid, dan antrakuinon. Penelitian ini bertujuan memformulasikan ekstrak etanol bawang dayak (Eleutherine bulbosa) ke dalam bentuk sediaan pasta gigi gel. Ekstrak bawang tiwai dengan konsentrasi 2,5% diformulasi menjadi pasta gigi gel dengan variasi sorbitol 5% - 50% dan CMC 3% - 7%. Evaluasi yang dilakukan meliputi organoleptis, homogenitas, pH, viskositas, daya sebar dan freeze-thaw cycling test. Hasil pengamatan organoleptik menunjukan adanya perubahan warna pasta gigi gel menjadi terbentuk 2 lapisan gel. Rentang pH pasta gigi gel 5,50 - 5,80, rentang uji daya sebar 4,61 – 5,82 cm, rentang viskositas 17066 - 99877 mPas. Hasil sentrifugasi dan cycling test menunjukkan tidak terjadi perubahan organoleptis, homogenitas, pH, dan viskositas pasta gigi gel.

Development of a Test Procedure for Freeze-Thaw Durability of Geomaterials Stabilized With Fly Ash

Abstract The objective of this research was to develop a freeze-thaw cycling test procedure and to investigate how the volume, moisture content, resilient modulus (Mr), and unconfined compressive strength (qu) of geomaterials, including soils and recycled materials, stabilized with fly ash change after freeze-thaw cycling. Three different types of materials (fine-grained and coarse-grained soils and recycled pavement materials) and five different fly ashes were used at different percentages (10, 12, 14, and 20 % by dry weight). Both one-dimensional and three-dimensional freezing of the specimens were considered. Freezing in three-dimensional was faster in terms of completing the freeze-thaw cycling and provided very similar results to the ones prepared in one-dimensional. Thus, three-dimensional freezing was adopted in this study without access to water (i.e., closed system). The results of this study indicated that the volume of all soil-fly ash mixtures tended to increase after freeze-thaw cycling; however, the volume change was not significant. Resilient modulus tests were conducted on all unstabilized materials, as well as on their mixtures with fly ash, while qu tests were conducted only on fine-grained soil and their fly ash mixtures. The Mr of all mixtures with one exception decreased by an average of 28.5 % when specimens were subjected to freeze-thaw cycling. The drop in the Mr of the specimens leveled off after 5 freeze-thaw cycles. A general trend of higher Mr of materials stabilized with fly ash (from 3 to 168 %), even after freeze-thaw cycles compared to unstabilized material was observed. In general, a reduction in unconfined compressive strength (qu) after freeze-thaw cycles up to 70 % was obtained. However, results showed that qu of stabilized soils that were subjected to freeze-thaw cycles were still higher (from 6 to 157 %) than the qu of unstabilized soils.

Durability of reactive powder concrete under chloride-salt freeze–thaw cycling

The corrosion of reinforcements that results from chloride iron erosion and freeze–thaw damage is the key cause of concrete material failure. Indoor accelerated freeze–thaw cycling tests on reactive powder concrete are carried out in this study, and the mass-loss rate (MLR), relative dynamic-elastic modulus (RDEM), and compressive strength are measured in order to evaluate its durability. In addition, the microstructure and composition of the reactive powder concrete during the chloride-salt freeze–thaw cycles were analyzed using scanning electron microscopy, energy-dispersive spectroscopy, and mercury-intrusion porosimetry. The results show that the reactive powder concrete was durable under chloride freeze–thaw cycling. Furthermore, the values of MLR and RDEM indicated that the actual method is not suitable for reactive powder concrete and should be modified, and that ettringite-type erosion products are generated during the freeze–thaw cycles. The conclusions in this study are valid for specific reactive powder concrete mix.

An Artificial Neural Network Based Analysis of Factors Controlling Particle Size in a Virgin Coconut Oil-Based Nanoemulsion System Containing Copper Peptide.

A predictive model of a virgin coconut oil (VCO) nanoemulsion system for the topical delivery of copper peptide (an anti-aging compound) was developed using an artificial neural network (ANN) to investigate the factors that influence particle size. Four independent variables including the amount of VCO, Tween 80: Pluronic F68 (T80:PF68), xanthan gum and water were the inputs whereas particle size was taken as the response for the trained network. Genetic algorithms (GA) were used to model the data which were divided into training sets, testing sets and validation sets. The model obtained indicated the high quality performance of the neural network and its capability to identify the critical composition factors for the VCO nanoemulsion. The main factor controlling the particle size was found out to be xanthan gum (28.56%) followed by T80:PF68 (26.9%), VCO (22.8%) and water (21.74%). The formulation containing copper peptide was then successfully prepared using optimum conditions and particle sizes of 120.7 nm were obtained. The final formulation exhibited a zeta potential lower than -25 mV and showed good physical stability towards centrifugation test, freeze-thaw cycle test and storage at temperature 25°C and 45°C.

Dispersive liquid-liquid microextraction based on solidification of floating organic drop and high-performance liquid chromatography to the analysis of cocaine's major adulterants in human urine.

A simple method has been proposed for the determination of cocaine's major adulterants (caffeine, levamisole, lidocaine, phenacetin, diltiazem, and hydroxyzine) in human urine by dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) in combination with high-performance liquid chromatography - photodiode array detector (HPLC-PDA). The reversed-phase chromatographic separation was obtained with a column C18 extended (250×4.6mm; 5μm; 80Å) in gradient elution mode using acetonitrile-trifluoroacetic acid 0.026% (v,v) (pH=2.5) at 1mLmin-1 as mobile phase, at 25°C, and detection at 235nm. The analysis time was 25min. This condition had the best resolution factors (>1.15), retention factors (>0.68), number of plates (>2094.9), and separation factors (>1.05) for all targets, indicating a good separation. The kind of extraction and dispersive solvent were investigated for unifactorial design. The buffer pH, the volume of extraction and disperser solvent, and the amount of salt were optimized for full factorial design. Under optimum conditions, human urine samples were alkalized with 0.5M sodium phosphate buffer (pH 10) and added to sodium chloride (20%m/v). Acetonitrile (150μL) and 1-dodecanol (30μL) were used as dispersive and extraction solvent, respectively. The method presented linear range of 312.5-3125ngmL-1 to caffeine and levamisole and 187.5-1875ngmL-1 to lidocaine, phenacetin, diltiazem, and hydroxyzine. The limit of quantification was 187.5ngmL-1 to lidocaine, phenacetin, diltiazem, and hydroxyzine and 312.5ngmL-1 for caffeine and levamisole. The recovery mean values were between 6.0 and 42.6%. The method showed good precision and accuracy, with within- and between-run relative standard deviation and relative error less than 15%. The samples were stable after freeze-thaw cycle and short-term room temperature stability tests. Besides, this method was satisfactorily applied in urine of cocaine users. It is expected that this method, which was the first to combine the use of DLLME-SFO and HPLC-PDA for the determination of cocaine's major adulterants in human urine, will contribute to the accuracy in the diagnosis of acute intoxication, the proper planning of therapeutic measures, as well as to the favorable prognostic of cocaine intoxicated patients.

Experimental study on strength and durability of lightweight aggregate concrete containing silica fume

In this study, the mechanical property and durability performance of high strength lightweight aggregate concrete (LWAC) with silica fume for 91days were presented. LWACs were designed to have the design compressive strength of 60MPa at 28days and the oven-dry density below 1900kg/m3. Nine mixtures with three aggregate types and silica fume replacement ratio of 0%, 3.5% and 7.0% by cement weight were prepared. The splitting tensile strength, the compressive strength and the modulus of elasticity tests were conducted at 7days, 28days, 56days and 91days. The chloride penetration resistance tests were done at 28days, 56days and 91days. The chloride diffusion coefficient based on the measurement of chloride penetration depth was also measured at 7days, 14days, 28days, 56days and 91days. The rapid freeze-thaw cycling tests were conducted and the relative dynamic modulus was evaluated up to 300 cycles. The results indicate that the durability against chemical deterioration for LWAC incorporated to silica fume depends on the compositions of hardened cement pastes in concretes, while the durability against physical attack depends on the types of aggregates.

Graphene Oxide Impact on Hardened Cement Expressed in Enhanced Freeze–Thaw Resistance

AbstractGraphene oxide (GO) is a newly invented material with extraordinary properties. This paper presents the effect of graphene oxide addition on freeze–thaw resistance in hardened cement. GO is incorporated in the cementitious matrix in ratios of 0.01, 0.03, and 0.06% by weight of cement. Freeze–thaw cycle tests show a weight loss of approximately 0.8% after 540 cycles in the control mix compared to approximately 0.25% in 0.06% GO mix. Several tests were conducted to investigate the reasons behind this result. The tests included nitrogen and water adsorption, air content, and compressive strength. The results showed that GO mixes have finer pore structure than the control mix. Moreover, the results indicated that GO addition increases air content in the mix and shows high compressive strength compared to the control mix. The enhancement of freeze–thaw resistance due to GO addition can be because of the modification of pore structure where water hardly freezes in small pores. Also, the resistance of na...