Ring Test Method Research Articles

Evaluation of Bitumen Modification Using a Fast-Reacting SBS Polymer at a Low Modifier Percentage.

The study presented in this paper investigates the application of asphalt bitumen modification using a fast-reacting SBS polymer at a low modifier percentage. The hypothesis is that a fast-reacting styrene-butadiene-styrene (SBS) polymer that composes only 2% to 3% of the weight of the bitumen modification could extend the life of the pavement surfacing and pavement performance at relatively low input costs, increasing the net present value produced by the pavement during its life cycle. To confirm or refute this hypothesis, two types of road bitumens CA 35/50 and 50/70 were modified with low amounts of fast-reacting SBS polymer with the expectation of attaining properties similar to a 10/40-65 modified bitumen. For each type of unmodified bitumen, bitumen modification and comparative 10/40-65 modified bitumen, the following tests were conducted: needle penetration, softening point-ring and ball test method, and ductility test. The second part of the article focuses on a comparison of asphalt mixtures with different compositions of coarse-grain curves. For each mixture, complex modulus with varying temperatures and fatigue resistances are represented by the Wöhler diagram and compared. Based on in labo testing, the impact of the modification on pavement performance is evaluated. Life cycle changes for each type of modified and unmodified mixtures are quantified as road user costs, and attained benefits are compared with increased construction costs.

Application of Cement-Based Carbon Fiber Material in Construction of Building Durability.

In order to solve the problem of drying shrinkage of cement-based carbon fiber materials in the early stage of hardening, the author proposes the application of cement-based carbon fiber materials in the construction of building durability. The author uses a self-designed fast ring test method to test and study the drying shrinkage performance of cement-based carbon fiber materials in the early stage of hardening. The results showed that the addition of MP-I and MP-II fibers, which can significantly reduce shrinkage cracking in plastic concrete, has little effect on preventing the shrinkage and cracking of concrete in the early stage of hardening. Mixed with a certain amount of steel fiber, carbon fiber, MH-I, and MPH-I hardened anticrack fiber, all have a better effect on preventing early water loss and drying shrinkage of hardening. The MH-I and MPH-I hardening anticracking fibers have an economical and feasible dosage, and the early water loss shrinkage and crack reduction rates of concrete hardening are 71.2% and 79.0%, respectively. MH-I fibers have no anticracking effect in the plastic stage and are only suitable for shrinkage and crack prevention of concrete in the early stage of hardening, while MPH-I hardened anticrack fibers have a 100% crack-reducing effect in the plastic stage, it is an engineering fiber material that can simultaneously prevent the plasticity and early hardening of concrete from shrinkage and cracking. The application of MPH-I hardened anticrack fiber is of great significance to improve the quality of structural engineering.

Effect of superabsorbent polymers on mechanical strength and cracking of mortar and concrete with water to cement ratios of 0.4 and 0.5

AbstractMost studies of adding superabsorbent polymers (SAP) into concrete focus on high‐strength concrete, while this paper aims to understand the influence of SAP on “ordinary concrete” at a w/c ratio being 0.4 or 0.5. The proposed experiments include the effect of particle size, mixing methods, and dosages on the restrained shrinkage and mechanical properties of mortar and concrete. Mortar with varying dosages of SAP (0.1, 0.2, and 0.3 wt.%) and two types of SAP (type‐a of 30–60 mesh and type‐d of 300–400 mesh) was studied to evaluate the effect of SAP on mortar's cracking and strength. Two mixing processes of SAP (dry and pre‐wetted) were used to examine the effect of SAP on the mortar's shrinkage and mechanical properties. Furthermore, concrete specimens with a w/c ratio of 0.5 were prepared to investigate the cracking performance of concrete using the restrained squared concentric ring test method, a new approach which can predict the cracks location and pattern to evaluate the restrained shrinkage of concrete. The result revealed that the addition of SAP in a prewetted state decreased the mechanical properties at early curing age. The addition of 0.3 wt.% SAP was found to have mitigated the restrained shrinkage while prolonging the time to cracking of cementitious composites. The major finding is that adding SAP to ordinary concrete reduces shrinkage and improves mechanical strength, which should be further looked into and explored in its application in engineering work.

Fatigue Performance Analysis of GRE Composite Pipes by Conducting Tension-Tension Tests on the Rings Cut from the Pipe

Abstract The main purpose of this study is to analyze the fatigue behavior of an industrial (±55°)9 filament-wound glass reinforced epoxy pipe. Fatigue tests are conducted in accordance with ASTM D2992, Standard Practice for Obtaining Hydrostatic or Pressure Design Basis for Fiberglass (Glass-Fiber-Reinforced Thermosetting-Resin) Pipe and Fittings, but instead of the entire pipe, rings cut from the pipe are used in the tests. This standard proposes a frequency of 0.42 Hz and stress ratio of R = 0.05. Tension-tension fatigue tests are performed on the rings at different load levels from 60 to 90 % of the ultimate hoop strength of the pipe. After the tests, the maximum pressure and maximum hoop stress curves versus the number of cycles to fatigue failure are presented. A comprehensive discussion about the importance of substituting the ring test method with ASTM D2992 standard test methods to determine the long-term performance of the composite pipes in the future is presented. The microscopic fatigue failure mechanisms of the rings are also characterized and interpreted using a scanning electron microscope.

A theoretically-based novel protocol for the analytic treatment of the glass failure stresses associated with coaxial double ring test method

With the aim of validating a new standardized Coaxial Double Ring testing procedure, without overpressure and with fixed geometry, an ad hoc theoretical approach has been proposed here to rearrange the laboratory outcomes accounting for the effects of the geometric non-linearities associated with such a testing configuration. By borrowing this idea, once the experimental values of the failure load have been determined, it has been possible to obtain an expression in closed form (fully defined by only two coefficients) of the maximum tensile stress (σmax) in the core of the specimen. Following this, in order to make the laboratory outcomes comparable and homogeneous, the σmax-values have been then re-scaled to a common reference condition (equibiaxial stress on a reference area, σeqbx), by means of the use of a correction coefficient (K) able to determine, under a condition of equal probability of failure, the effective area (Aeff) of the tested specimens. After being corrected to account for the effects of the stress corrosion cracking (static fatigue effect), all re-scaled data have been finally interpreted using a Weibull-type statistical distribution to determine the main fractile values of the glass strength. Doing so, despite some unavoidable approximations, this procedure furnished a highly effective means of determining the bending strength of float glass. Unlike the pure numerical approach proposed in codes and literature, which requires to correct the experimental data via FEM simulation, the rationale behind the proposed approach is in fact to elaborate the experimental data through an analytic treatment of the problem, which would greatly facilitate the interpretation of the data as well as the standardization of the testing procedure.

Mathematical modeling of AZ30 magnesium alloys at high temperature using the ring compression test and genetic algorithm method

Abstract In the present investigation, a new method is proposed to study the AZ30 flow curve at elevated temperatures and various strain rate. Experiments were carried out with the goal of obtaining flow curve of AZ30 at three different temperature and strain rates by using the ring test method. The presented work aims to develop a model using genetic algorithm for AZ30 flow stress prediction during different test conditions. The Santam machine was implicated that was able to perform experiments by controlling both the position and load modes. At each temperature and strain rate the isothermal test was performed respectively. In the present investigation for three varios temperatures and strain rates, 54 ring compression tests were carried out with different levels of reduction in height. Then each specimen was water cooled quickly to investigate the microstructure of AZ30 magnesium alloy by using optical microscope. The model used in the present study was able to predict the flow curve with an 2.3% accuracy. This model has excellent potential to be employed in various industry applications.

Effect of ultrasonic melt treatment on the tribological behavior of 7075 aluminum alloy

Abstract In this study, the tribological properties of 7075 aluminum alloy produced by ultrasonic melt treatment (UST) are investigated. Tribological properties of untreated and ultrasonically treated samples under dry and lubricated sliding conditions were analyzed experimentally by the block on ring test method. Worn surfaces of untreated and ultrasonically treated samples were scanned by 3D optical profilometer and analyzed to search out wear characteristics in the material. Furthermore, microstructural examinations were conducted to investigate the beneficial effects of UST on the microstructural properties of the alloy using optical and scanning electron microscopy. According to the results obtained, UST refines the α-Al phase of the alloy and disperses precipitates to grain boundaries more uniformly. Also, hardness and density of the alloy increased through the effect of UST. Due to these favorable effects, the wear resistance of the alloy increased and the worn surfaces of the ultrasonically treated samples exhibited lower surface roughness according to 3D surface roughness measurements.

Effect of ultrasonic melt treatment on the tribological behavior of 7075 aluminum alloy

Abstract In this study, the tribological properties of 7075 aluminum alloy produced by ultrasonic melt treatment (UST) are investigated. Tribological properties of untreated and ultrasonically treated samples under dry and lubricated sliding conditions were analyzed experimentally by the block on ring test method. Worn surfaces of untreated and ultrasonically treated samples were scanned by 3D optical profilometer and analyzed to search out wear characteristics in the material. Furthermore, microstructural examinations were conducted to investigate the beneficial effects of UST on the microstructural properties of the alloy using optical and scanning electron microscopy. According to the results obtained, UST refines the α-Al phase of the alloy and disperses precipitates to grain boundaries more uniformly. Also, hardness and density of the alloy increased through the effect of UST. Due to these favorable effects, the wear resistance of the alloy increased and the worn surfaces of the ultrasonically treated samples exhibited lower surface roughness according to 3D surface roughness measurements.

Abrasive wear performance of multi-layer interwoven polyester fiber & PTFE particle reinforced polyester composite

This study aims to systematically investigate the abrasive wear performance of composite material with multi-layer polyester fiber interweaving and PTFE particle reinforced polyester matrix under dry friction conditions. Abrasive wear performance experimentally investigated by applying the block on ring test method depending on the direction of fiber weaving. The test material exposed to pure water, mineral oil, HNO3, and NH3 for 1, 2, 3, 4 weeks. The sliding distances and test durations were determined to be 2.26, 4.52, 6.78 and 9.04 km, 1, 2, 3 and 4 hours respectively. The best wear resistance was obtained in the perpendicular direction to the fiber reinforcement. While HNO3 and NH3 environments significantly decrease the wear resistance, oil and pure water environments increase the wear resistance by lubricant effect.

TOKAT İLİ ÇEVRE KÖYLERİNDEN ELDE EDİLEN SÜTLERDE BRUCELLA CİNSİ BAKTERİLERİN VARLIGININ ARAŞTIRILMASI

Brucellosis is one of the most common zoonotic diseases caused by Brucella. The disease is located genital organs in the females of mammals such as cattle, sheep, goats, dogs and pigs and cause to infertility, mastitis, preterm birth, placenta retention and metritis; in men it causes orchitis (gonorrhea inflammation). The bacteria can also spread from animals to humans and cause disease in humans. The aim of this study was to determine the prevalence of Brucellosis in milk collected from villages of Tokat province and districts. For this purpose, 161 cows, 58 sheep and 33 goat milk samples were investigated by Brucellosis agent with Milk Ring Test (MRT) and direct sowing method. At the end of the study, 24 of 161 cow's milk, 20 of 58 sheep's milk and 5 of 33 goat's milk were found to be positive by MRT. Of the 252 raw milk samples, 49 (n = 19.41%) were positive for MRT. Brucella melitensis biotype 3 were isolated from the 2 milk samples after the culturing from 49 samples with positive MRT. It was determined that 2 milk samples isolated from Brucea belong to 2 different sheep from the same herd. Thus, Brucella was isolated in 0.79% of all studied samples, 4.08% of MRT positive samples and 3.45% of sheep milk samples. As a result of our first study with milk collected from the villages and towns of Tokat province and districts, 19.41% of the samples were positive for MRT and 0.79% of the samples were isolated by direct planting method. Thus, in this study, it was determined that there is a certain amount of Bruceila agent in Tokat province and its districts and it shows that dairy products may pose a risk for Brucellosis.

Study of concrete shrinkage behaviour using the restrained squared eccentric ring test method

Four types of cement-based concrete specimens were analysed in this study – high-fluidity concrete, semi-dry concrete, high-fluidity crumb rubber concrete with a rubber content of 110 kg/m3 and semi-dry crumb rubber concrete with a rubber content of 110 kg/m3. The restrained squared eccentric ring test method was applied to measure the restrained shrinkage strains at early age (first 5 d) in the 0, 90 and 180° zone of the specimens, as well as the time when the specimens cracked. All 12 specimens cracked near the 0° zone, and the values of restrained shrinkage strains in the 0, 90 and 180° zones showed a decreasing sequence. Compared with the ordinary concretes without crumb rubber, the restrained shrinkage of the crumb rubber concretes was reduced and the cracking time was prolonged. The restrained shrinkage strains in the 0, 90 and 180° zone plotted against time showed a linear growth pattern. The ratio of shrinkage strain between the 0° zone and the 90° zone and that between the 0° zone and the 180° zone were practically invariable over time, suggesting that restrained shrinkage strains may be expressed mathematically by a product of a time-dependent function and a spatially dependent function, as postulated in a number of analytical studies.

Study on the Shrinkage Behavior of the Cement Mortar with the Additives of the Nano-Kaolinite Clay

The effect of nano-kaolinite clay (NKC) on the early age cracking behavior of cement mortar was investigated. The restrained ring-test method was used to detect shrinkage crack tendency of cement mortar specimen. The cracking and strain on the surface of mortar ring for the ordinary and NKC mortar were monitored. The development of crack width and strain during the drying process were obtained. Finite element analysis is carried out to simulate the evolution of the crack in restrained concrete rings subject to circumferential drying. The results demonstrate that the addition of NKC increases the shrinkage cracking tendency of mortar at early age. It is found that the crack width is significantly increased in the mortar specimen added with 3% NKC replacement.

Fracture strength prediction of float glass: The Coaxial Double Ring test method

The fracture strength of float glass (FG) is generally difficult to predict, since it is governed by a number of different factors. To bypass the influence of the above-mentioned variables, ruling out any possible source of uncertainty, a reliable testing procedure should be able to produce an equibiaxial stress state in the central part of the specimen. The Coaxial Double Ring (CDR) test configuration is able to achieve such an ideal condition, but only if geometric nonlinearities are of lesser importance. A number of alternative test set-ups have been investigated in recent years, but none of these offers such advantages as to be preferred a priori. To this end, this study aims at finding out, through experimental investigations, an alternative CDR configuration to predict the failure strength of glass plates as a starting point for the development of a design-by testing procedure. A total of 393 FG square-shaped specimens, with different edge lengths (100 or 400 mm) and thicknesses (4, 5, 6, 8 or 10 mm), were tested using four different types of CDR test set-ups (obtained by varying the dimensions of the loading area). Laboratory outcomes, after being corrected via FEM simulations, were then interpolated using a Weibull-type statistical distribution to derive the best-fit parameters of probability density functions, which were finally used to provide the characteristic values of the glass failure strength.

Influence of specimen geometries and drying conditions on concrete cracking in restrained elliptical ring tests

Abstract The restrained shrinkage elliptical ring test has been established as an efficient method for assessing the cracking potential of concrete at early ages because an elliptical ring can provide a higher degree of restraint compared with a circular one. In this study, a series of circular and elliptical concrete rings restrained by steel rings with various thicknesses were tested under top & bottom surfaces drying or outer circumferential surface drying. By comparing concrete cracking age under different geometrical and drying conditions, the effects of ring geometry, restraining steel ring thickness and drying condition on the cracking process in concrete rings were revealed. Furthermore, numerical analyses were conducted to investigate the fracture mechanism for circular and elliptical rings by applying a fictitious temperature field to simulate the shrinkage effect of concrete. It is found that the increase of steel ring thickness can enhance the degree of restraint, therefore shorten the cracking age for both circular and elliptical rings. However, the improvement is more significant for circular rings. The fracture processes under the two drying conditions, i.e. top & bottom surfaces drying and outer circumferential surface drying are completely different: for drying from outer circumferential surface, the crack initiates at the outer surface and propagates towards the inner surface; for drying from top & bottom surfaces, the crack initiates partially along the height direction at the inner circumference of a concrete ring, and propagates along the radial direction, step by step, until the crack propagates throughout the whole ring wall. In both cases, the self-restraint caused by the non-uniform shrinkage of concrete and the external restraint from the inner steel ring contribute the driving effects for crack propagation. In general, compared with circular rings, the elliptical rings demonstrate the advantage of providing a higher degree of restraint. The elliptical ring test method can, therefore, supplement the traditional circular ring test method for assessing cracking tendency of concrete with higher cracking resistance.

Assessment of behaviour and cracking susceptibility of cementitious systems under restrained conditions through ring tests: A critical review

Cracking occurrence due to shrinkage related effects is a widely recognised issue which is frequently evaluated with the shrinkage restraining ring test. This paper provides a state-of-the-art review of the ring test method, which has been used for the last four decades. The last review on such matter was conducted only in early 2000s; however, a significant amount of studies has been conducted since then and considerable advancements or modifications in this testing method have taken place over the last decade. Studies on the traditional ring test, i.e. a circular concrete ring cast around a steel ring, are identified and the history, tendencies, practices and quantitative methods are analysed thoroughly. Furthermore, any modifications/advancements in the testing method with respect to their purpose, applications and capabilities based on current knowledge, are addressed. Finally, an insight on the challenges that the developers of testing methods for restrained shrinkage are faced with is given together with perspectives for their future potential improvement.

A Review of the Diamond Retention Capacity of Metal Bond Matrices

This article presents a review of the current research into the diamond retention capacity of metal matrices, which largely determines the service life and working performance of diamond tools. The constitution of diamond retention capacity, including physical adsorption force, mechanical inlaying force, and chemical bonding force, are described. Improved techniques are summarized as three major types: (1) surface treatment of the diamond: metallization and roughening of the diamond surface; (2) modification of metal matrix: the addition of strong carbide forming elements, rare earth elements and some non-metallic elements, and pre-alloying or refining of matrix powders; (3) change in preparation technology: the adjustment of the sintering process and the application of new technologies. Additionally, the methods used in the evaluation of diamond retention strength are introduced, including three categories: (1) instrument detection methods: scanning electron microscopy, X-ray diffractometry, energy dispersive spectrometry and Raman spectroscopy; (2) mechanical test methods: bending strength analytical method, tension ring test method, and other test methods for chemical bonding strength; (3) mechanical calculation methods: theoretical calculation and numerical computation. Finally, future research directions are discussed.

Evaluation of early age cracking in rendering mortars with polypropylene fibers

Abstract The incorporation of fibers in concrete produces an improvement in the characteristics of the material as observed in different studies. In order to obtain the same good results, fibers are added to rendering mortars to reduce some of their drawbacks. However, this type of mortar has some specific characteristics, such as hydrated-lime utilization or higher air, which is not usual in concrete. Thus, this study aims to evaluate the potential of polypropylene fibers to reduce early age cracking caused by restrained shrinkage in rendering mortars. Two types of mortars were used to verify possible differences in the way they responded to the introduction of fiber. The influence of the fiber content was also investigated. Mortars were evaluated in fresh state, and mechanical behaviors were measured at several ages. The restrained shrinkage cracking was followed for 21 days using the ring test method. The use of polypropylene fibers leads a smaller value of total crack width and a delay of the first crack. Also, the elastic modulus shows a higher correlation with the mortars crack width. Both parameters were successfully used to predict the mortars crack width. The ring test method may be a suitable test method to evaluate the capacity of fibers to control the crack formation in rendering mortars.

Quantifying the influence of elliptical ring geometry on the degree of restraint in a ring test

A novel elliptical ring test method has been proposed to replace the traditional circular ring test method for the purpose of shortening test duration for assessing cracking tendency of concrete and more conveniently examining crack evolution in concrete rings. To further explore the mechanism of this new test method, a numerical model was established to analyse stress development and crack initiation in concrete rings in which a fictitious temperature field simulated the externally applied mechanical effects of concrete shrinkage on concrete causing the same strain as shrinkage does. The proposed numerical model was validated against experimental results and was then used to evaluate the effects of ring geometry on the degree of restraint to concrete. Moreover, a series of numerical experiments were conducted to derive the expression of the degree of restraint to elliptical rings. Through the error analysis of the degree of restraint on concrete properties and ring geometry, the expression was verified so that it can be used to calculate the degree of restraint provided by the internal steel ring. According to the derived expression, the restrained elliptical ring test can be designed to quantitatively simulate the service condition of concrete in an engineering structure more accurately.

Influence of magnetic water on early-age shrinkage cracking of concrete

This research investigates the shrinkage cracking of concrete, which were mixed with magnetic water. Magnetic water was obtained by the independent designed magnetizing equipment. Ring-test method and flat-test method were used to test early-age shrinkage cracking of concrete. Results show that the strain rate factor (α) and the total cracking area of unit area (c) of concrete were decreased when used magnetic water, which means the early-age shrinkage cracking resistance of concrete mixed with magnetic water is improved than those mixed with tap water. The best increase in early-age shrinkage cracking resistance of concrete is achieved when the magnetic strength is 260mT and the length of magnetic field is 280mm. Additionally, the compressive and split strength of concrete mixed with magnetic water increased greatly. It is also found that the length of magnetic field have direct effect on the growth of concrete strength.

Effects of specimen size on assessment of shrinkage cracking of concrete via elliptical rings: Thin vs. thick

An elliptical ring test method is proposed to replace the circular ring test recommended by ASTM and AASHTO for faster and more reliable assessment of cracking tendency of concrete. Numerical models are also established to simulate stress development and crack initiation/propagation in restrained concrete rings. Cracking age, position and propagation in various rings are obtained from numerical analyses that agree well with experimental results. Elliptical thin rings of certain geometry can shorten the ring test duration as desirable. In thin rings, crack initiation is caused by external restraint effect so that a crack occurs at the inner circumference and propagates towards the outer one. In thick rings, crack initiation is mainly due to the self-restraint effect so that a crack occurs at the outer circumference and propagates towards their inner one. Therefore, thick elliptical concrete rings do not necessarily crack earlier than circular ones as observed from experiment.