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The effectiveness study results related to "soft" multi-stage crushing mode of concrete scrap are presented. During the research it was found that the processing of concrete scrap using this technology can significantly improve the characteristics of the secondary concrete aggregate, namely crushability, water absorption and voids. It is achieved by reducing the content of cement bound stones in the secondary crushed stone. Significant volumes of the dispersed material formed as a result of such processing can be used as a fine filler part at production technology of the self-compacting concrete. An optimum organic-mineral additive based on nanoparticle with a superplasticizer, which allows to obtain a homogeneous concrete mixture with additional stabilization properties was used for self-compacting concrete. The stability of the rheological characteristics of the modified cement systems will be insured if an optimum amount of organic-mineral additive is used. It was revealed that 28 days strength of a self-compacting concrete with concrete scrap crushing products content reaches more than 55,6 MPa, hardened under normal conditions and more than 75 MPa after one year under air-dry conditions. [ABSTRACT FROM AUTHOR]

When used for sand casting, foundry sand is stressed in several ways. These stresses, thermal and mechanical, compromise the grain integrity, resulting in size reduction and the production of small particles to the point where the sand is no longer viable for sand casting. This study evaluates the crushability of chromite sand, a crucial characteristic for determining how resistant sand is to size reduction by crushing. To replicate the heat and mechanical strain that sand is subjected to during the industrial sand-casting process, a sinter furnace and rod mill were employed. After nine minutes of heat and mechanical stress application, the crushing ratio, which was used to gauge the crushability of chromite sand, ranged from 1.72 to 1.92 for all samples. There were differences in the rate at which fine particles were produced among the samples, with sample E producing the highest proportion of fine particles in the same length of time. Understanding the properties that control the crushability performance of chromite sand will enable foundries to buy chromite sand with higher recycling yield, reducing the environmental impact of waste foundry sand and eliminating the risk to the workforce's pulmonary health in line with the current industry standards. Foundries will also be able to optimize the current industrial process while continually pushing for innovative foundry technologies and materials.

Carbonated sands, also referred to as calcareous sediments, are a common type of soil in marine environments such as the West Australia Continental Platform, South China Sea, Persian Gulf and Oman sea and many parts of the world. During pile driving in such soils, imposed shear and volumetric strain to particles, crushing occurs which leads to change in the particle size distribution as well as interface properties of the soil-pile system. In this study, two types of sands (siliceous Firoozkooh-161 and carbonate Hormoz sand) and three types of materials (steel, wood and concrete) have been selected and were investigated using a direct shear and a tall oedometer apparatus for the prediction of the sand-pile interaction properties considering particle crushing. The smoothness and roughness of materials as well as soil relative density, and shearing rate on the interface properties were examined. Based on the results, smooth steel, wood at the direction of vessels, rough steel, smooth concrete, wood at the right angle to vessels, and rough concrete represent the lowest to the highest interface shear strength, respectively. Results revealed, increasing soil relative density leads to an increase in the interface friction angle. The results also emphasized that increasing the vertical stress leads to increasing in the breakage index both dense and loose states, however, the amount of particle increases with density. Particle crushing also decreases significantly when soil interact with smooth surfaces. Furthermore, increasing the shearing rate enhances the shear strength and reduces particle crushing. It also investigated that Hormoz sand compared to Firoozkooh sand exhibits a higher level of particle breakage due to the shape and texture of carbonated particles. Finally based on the achievements of this research, the limit values for skin friction bearing capacity of piles driven in carbonate and siliceous sands proposed in ARGEMA and API approach were examined. [ABSTRACT FROM AUTHOR]

When used for sand casting, foundry sand is stressed in several ways. These stresses, thermal and mechanical, compromise the grain integrity, resulting in size reduction and the production of small particles to the point where the sand is no longer viable for sand casting. This study evaluates the crushability of chromite sand, a crucial characteristic for determining how resistant sand is to size reduction by crushing. To replicate the heat and mechanical strain that sand is subjected to during the industrial sand-casting process, a sinter furnace and rod mill were employed. After nine minutes of heat and mechanical stress application, the crushing ratio, which was used to gauge the crushability of chromite sand, ranged from 1.72 to 1.92 for all samples. There were differences in the rate at which fine particles were produced among the samples, with sample E producing the highest proportion of fine particles in the same length of time. Understanding the properties that control the crushability performance of chromite sand will enable foundries to buy chromite sand with higher recycling yield, reducing the environmental impact of waste foundry sand and eliminating the risk to the workforce's pulmonary health in line with the current industry standards. Foundries will also be able to optimize the current industrial process while continually pushing for innovative foundry technologies and materials. [ABSTRACT FROM AUTHOR]

Determination of rock abrasivity using the LCPC test – Recommendation No. 24 of the Commission on Rock Testing of the Deutsche Gesellschaft für Geotechnik e. V. The Commission on Rock Testing of the Deutsche Gesellschaft für Geotechnik e. V. (German Geotechnical Society) is compiling instructions for rock testing in laboratory and in situ and for monitoring of rock masses and civil engineering structures. This recommendation No. 24 deals with the LCPC test for investigating hard rock samples in order to determine the abrasivity and the crushability of hard rock. The requirements for the test facility and sample preparation as well as the procedure for carrying out and evaluating LCPC tests are specified. The LCPC test was developed by the Laboratoire Central des Ponts et Chaussées and is used to classify the abrasivity and crushability of rock. This recommendation takes into account the French standard NF P 18‐579: 2013‐02 [1], but goes beyond it in terms of testing procedure and evaluation. The abrasivity index is determined by exposing a defined steel test plate to a granular sample at a defined speed of rotation for a defined amount of time. The material loss of the test plate is measured and applied for the calculation of an index value for the abrasivity of the original hard rock sample. In addition, an index value for the crushability can be determined from the change in grain size compared to the initial sample. [ABSTRACT FROM AUTHOR]

Understanding the effect of particle size on the shear strength of granular materials is important for geotechnical design and construction. However, previous studies show contradicting results on the relationship between particle size and shear strength. Additionally, the effect of particle breakage on this relationship has not been fully revealed. In this study, a series of biaxial tests have been simulated with the discrete element method to explore the particle-size effect of sand considering the role of particle breakage. The sand specimens have parallel particle-size distributions. The sequential breakage model has been used to simulate particle breakage, which is a combination of replacement and cluster methods. The main conclusions of this study are: (1) the relationship of peak shear strength and particle size depends on the crushability of particles and relative density of specimens; (2) the particle size and crushability have a very slight effect on the residual shear strength; and (3) at the microscale, the relationship between shear strength and particle size is positively related to the friction utilization ratio. [ABSTRACT FROM AUTHOR]

Carbonate sediments are originated from the skeletal remains of marine organisms, which are abundantly situated at the tropical and petrochemical reservoir in Australia, India, the North Sea coasts, and the Persian Gulf. The different behavior of carbonate remains in comparison to siliceous soils has attracted attention among researchers. Crushability is a significant feature of carbonate sands which leads to changes in particle size distribution at high pressures and causes enormous damage to structures. This study aims to evaluate the compressibility of Hormuz Island carbonate sand and compare it to the Chamkhaleh Beach siliceous sand through one-dimensional compression tests in a pneumatic oedometer apparatus. Experiments were subjected to overburden pressures up to 2 MPa, and grain crushing was measured after each experiment. Results illustrated that particle crushing in the Hormuz Island sand impacted its compressibility and led to an abrupt increase in strain and settlement. [ABSTRACT FROM AUTHOR]

Introduction. The use of the thermal power station’s (TPS) waste in the construction industry becomes the norm in world practice of recent decades. Basically, the researches use ash and slag in the construction of automobile roads as a material for filling the subgrade or in the form of a cement-bound material in industrial and civil construction as a material for planning work, when filling inconveniences and quarries. However, the potential of the ash and slag’s usage is much wider. Coarse-grained slag deposits that form in the zone of slag erosion have a greater potential for application than other ash and slag mixtures, however, these mixtures have been less studied by both domestic and foreign researchers. The paper discusses the use of the boiler slag formed at power plants with boilers involving liquid slag removal for the construction of road pavement bases with the position of its mechanical properties.Materials and methods. The author studied samples of boiler slag from Novosibirsk TPS-2, operating (Kuznetsk coal basin) and Novosibirsk TPS-3 (Kansko-Achinsk coal basin). Moreover, the author determined the crushing losses of individual fractions of the investigated materials in a dry and water-saturated state. The author determined the modulus of deformation of boiler slag.Results. The researcher found the difference in mechanical strength of the different genesis material. The crushing values of the investigated materials are determined.The author estimated the graphs obtained during testing and calculated the deformability characteristics of the material.Discussion and conclusions. The author determines possible directions of the studied materials’ usage in the road construction.The author has read and approved the final manuscript. Financial transparency: the author has no financial interest in the presented materials or methods. There is no conflict of interest.

The present research investigates the undrained behavior of calcareous sand of Qeshm island in the south of Iran. The study was performed through undrained cyclic and monotonic stain-controlled triaxial tests on two relative densities (40 and 70%) and different effective confining pressures. Five different amplitudes of strains including 0.01 , 0.07 , 0.14 , 0.7 , and 1 % were applied for cyclic triaxial tests. Additionally, both loose and dense samples of Qeshm calcareous sand show rather a ductile behavior and clear failure plane under monotonic loading were not observed upon shearing of the samples. The increase in effective confining pressure led to higher excess pore water pressure under cyclic loading. This increment was especially clear in larger amplitudes of applied cyclic strain. The increase in relative density and over consolidation ratio (OCR) enhanced the shear modulus and reduced liquefaction potential. Moreover, particle breakage was increased by increasing shear strain and effective confining pressure. However, the increase in relative density decreased particle crushing of Qeshm calcareous sand. [ABSTRACT FROM AUTHOR]

This study investigates the small strain stiffness (Gmax) of six coal bottom ashes in South Korea. One-dimensional compression tests using an instrumented oedometer cell were performed to measure the shear wave velocity (Vs), and the compression indices (Cc) of the six different bottom ashes were also explored in this study. The results demonstrate that, at low confinement, the Cc of bottom ashes are comparable to that of sand under a similar void ratio. However, at high confinement, the bottom ash shows very high Cc compared to sand due to the crushability of the weak and porous bottom ash particles upon confinement. The variations of α and β, which are Vs parameters (i.e., Vs = α (σ′m/1 kPa)β), with different Cc values of the tested bottom ashes are consistent with the existing empirical relationship. The Gmax of tested bottom ashes can be adequately captured by the existing Gmax estimating formula for angular sand, indicating that the Gmax of bottom ash is highly comparable to that of sand with a similar void ratio and confining stress. [ABSTRACT FROM AUTHOR]

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Micaceous soil is believed to be detrimental for civil engineering constructions due to the effect of high compressibility, low compacted density and low shear strength. Individual mica particle has numerous intact mica flakes foliated over each other making it flexible upon loading and rebound upon unloading due to its low hardness and resilient nature. Hence, micaceous soils with mica content more than 10% are considered undesirable for highway pavements, embankments and railway track constructions. When platy mica particles are sufficiently numerous to interact with spherical sand particles, bridging and ordering phenomena are augmented within the soil mass creating unique sand-mica particle orientation (MS microstructure) unlike sand-sand particle orientation (PS microstructure). The current experimental research was conducted to evaluate the variation in stress–strain, pore pressure and effective stress path response of Sabarmati sand under the influence of mica (sand with 30% mica and pure sand) with MS and PS microstructure respectively. Effect of particle crushing on stress–strain and pore pressure response was also studied on Sabarmati sand with MS and PS microstructure. Distinctive macroscopic response was observed in Sabarmati sand with MS microstructure under the influence of mica as well as mica particle crushing. [ABSTRACT FROM AUTHOR]

Introduction. Production waste is used in the construction industry worldwide as it helps to cover a considerable portion of the industry's demand for building materials. Coarse-grained slag deposits (slag crushed stone and sand), formed in the slag washout zone, have more potential for application than other ash and slag mixtures (coarse ASM), but they need more research. Mechanical properties of the slag crushed stone (coarse-grained ASM), formed in the course of coal combustion at Kansk-Achinsk, Kuznetsk coal deposits (in boilers equipped with liquid and dry slag removal facilities) and the application of the slag crushed stone in roadbuilding are considered. Materials and methods. In the course of the research, the crushability and the deformation modulus of particular fractions of slag crushed stone samples (in dry and water-saturated conditions) taken from the dumps of Novosibirsk TPP-3 (that consumes the coal of the Kansk-Achinsk coal mining field) and from Novosibirsk TPP-2 and Seversk TPP (that consume the coal of the Kuznetsk coal mining fi eld) were identified. To assess the factors influencing the mechanical strength of the slag crushed stone, ignition losses, the content of flaky and acicular particles, dust and clay particles and clay lumps was made. Results. The diff erence in the mechanical strength of samples having diff erent genesis was identified. The graphs obtained in the course of testing were assessed and deformability characteristics were calculated (for materials having different fineness values). The factors influencing the mechanical strength of slag crushed stone were determined. Dependencies between deformation parameters and crushability of the slag crushed stone were obtained. Conclusions. Some mechanical and physical parameters of the slag crushed stone were identified; th ey were applied to outline potential areas of the slag crushed stone application in road building. The mathematical relationship needed to project the deformation modulus of the slag crushed stone was identified. This relationship will be used to design structures to be made of this material. [ABSTRACT FROM AUTHOR]

In this paper, crushability of foundry sand particles was studied. Three kinds of in-service silica sands in foundry enterprises selected as the study object, and foundry sand particles were subjected to mechanical load and thermal load during service were analyzed. A set of methods for simulating mechanical load and thermal load by milling and thermal-cold cycling were designed and researched, which were used to characterize the crushability for silica sand particles, the microstructure was observed by SEM. According to the user’s experience in actual application, the crushability of Sand C was the best and then Sand B, the last Sand A. The results indicated that mechanical load, thermal load and thermal-mechanical load can all be used to characterize the crushability of foundry sand particles. Microscopic appearances can qualitatively characterize the crushability of foundry sand particles to a certain extent, combining with the additions and cracks which are observed on the surface.

Abstract The surface layer of the northern coastal line in Egypt is mainly comprised of calcareous sand, resulting from erosion of limestone and calcarenite ridges. These calcareous sand formations, are considered problematic due to their possible crushability and high compressibility. Reconstituted calcareous sand is mixed with different ratios of broken shells to investigate the effect of particle crushability on the strength behavior. The strength and crushability are evaluated using laboratory direct shear, triaxial compression and one-dimensional consolidation. Crushability of medium to fine uniform calcareous sand is found to be insignificant. Reconstituted sand-shell samples that contain 30% or more by weight of broken shells have exhibited a reduction of about 20% in the peak angle of shearing resistance. Sand-shell mixtures, with broken shells content of 30% or more, show significantly higher compressibility and consequently lower soil modulus. Simplified equations are proposed to express the degradation of the constrained modulus due to crushability. [ABSTRACT FROM AUTHOR]

Crushing is a size reduction process that plays a key role in both mineral processing and crushing-screening plant design. Investigations on rock crushability have become an important issue in mining operations and the manufacture of industrial crusher equipment. The main objective of this research is to quantify the crushability of hard rocks based on their mineralogical and mechanical properties. For this purpose, the mineralogical, physical, and mechanical properties of various hard rocks were determined. A new compressive crushing value (CCV) testing methodology was proposed. The results obtained from CCV tests were compared with those from mineralogical inspections, rock strength as well as mechanical aggregate tests. Strong correlations were found between CCV and several rock and aggregate properties such as uniaxial compressive strength (UCS), the brittleness index (S20), and aggregate impact value (AIV). Furthermore, the relationship between the mineralogical properties of the rocks and their CCVs were established. It is concluded that the proposed testing methodology is simple and highly repeatable and could be utilized as a pre-design tool in the design stage of the crushing process for rock quarries. [ABSTRACT FROM AUTHOR]

Cement is a basic material, which plays an important role in ensuring national economic construction. Cement grinding roller press plays an important role in cement production and grinding process. The grinding roller is the key component on the grinding roller press and the abrasion loss is quite large. Therefore, increasing the wear resistance and reducing abrasion loss of the grinding roller press will bring huge economic benefits to cement production. Organisms have evolved a large number of non-smooth surface structures in the process of natural selection. Such as the scale structure on the surface of the pangolin, the fringe structure on the shell surface, the blocky protuberance structure on the surface of the lizard, etc. These non-smooth structures play an important role in improving wear resistance and reducing abrasion of biological surfaces. In order to improve the wear resistance and fragmentation of cement grinding roller press. Based on the excellent wear resistance and drag reduction characteristics of the non-surface structure. Guided by bionics non-smooth theory. According to the working principle and actual size of the grinding roller press. The bionic pit shape structure with different depth, different diameter, different axial spacing and different circumferential angle designed on the surface of grinding roll. Each factor selected at two levels. The factors of the pits arranged according to the orthogonal experimental design method. The grinding roller machined according to orthogonal experimental design. To do the wear test of the grinding roller after processing carried out. The composition and structure of the test bench are basic the same as the actual roller press. Two relatively rotating grinding rollers driven by an electric motor. The grinding rollers extruded the abrasive quartz sand in the middle of them. The wear condition judged by measuring the quality loss. The test results showed that the reasonable bionic pit structure could significantly improve the wear resistance of the grinding roller. The wear resistance of the grinding roller improved by 29.06% compared with the standard grinding roller. In order to explore the wear mechanism of bionic grinding roller, the force analysis of the grinding roller analyzed by finite element software. The reasonable bionic pit shape structure could effectively reduce the stress in the inner surface and the stress distribution of grinding roller surface. It can also reduce the stress gradient and optimize the force on the grinding roller surface, reduce abrasion and improve wear resistance. The crushing test of the grinding roller carried out according to the orthogonal experimental design. The fragmentation rate of quartz sand used as a criterion for evaluating crushability. The bionic pit structure can effectively improve the crushability of the grinding roller according to the test results. Its crushability increased by 18.7% compared with the standard grinding roll. Combined with the explicit dynamic finite element method to explore the crushing process of grinding roller. It found that the maximum extrusion pressure was an important factor affecting the crushability of grinding roller. It found that the maximum extrusion pressure was an important factor affecting the crushability of grinding roller. It was the best grinding roller with both wear resistance and breakage when the diameter of the pit is 8 mm, the depth of the pit is 2 mm, the distance of the axial pit is 16 mm and the number of circumferential pit is 12. The single particle crush test of the bionic grinding roller carried out and the whole process of quartz sand breakage recorded by high-speed camera. Compared with the standard grinding roll, the bionic pit shape grinding roller can seize quartz sand quickly, form transient stability structure, reduce the sliding probability of quartz sand on the grinding roller surface. Reduced the probability of scratch on the grinding roll surface by the quartz sand. The bionic pit shape structure makes the single point support become multi-point support in the process of extruding quartz sand by grinding roller. The extrusion force dispersed which was the important reason to improve the abrasion resistance and crushability of the grinding roller press. [ABSTRACT FROM AUTHOR]

In this paper, crushability of foundry sand particles was studied. Three kinds of in-service silica sands in foundry enterprises selected as the study object, and foundry sand particles were subjected to mechanical load and thermal load during service were analyzed. A set of methods for simulating mechanical load and thermal load by milling and thermal-cold cycling were designed and researched, which were used to characterize the crushability for silica sand particles, the microstructure was observed by SEM. According to the user's experience in actual application, the crushability of Sand C was the best and then Sand B, the last Sand A. The results indicated that mechanical load, thermal load and thermal-mechanical load can all be used to characterize the crushability of foundry sand particles. Microscopic appearances can qualitatively characterize the crushability of foundry sand particles to a certain extent, combining with the additions and cracks which are observed on the surface. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to discretely model rockfill materials considering the irregular shape of the particles and their crushability. The scientific goal was to investigate the influence of particle crushability and shape on the mechanical behavior of rockfill materials. Design/methodology/approach – The method of generating irregular-shaped particles was based on the observation that most rockfill grains can be approximately circumscribed by an ellipsoid. Two shape descriptors were used to make the virtual particles closely replicate the geometric features of natural rockfill grains. The combined finite-discrete element method (FDEM) was used to numerically simulate a drained, tri-axial compression test. The particle assemblies were subjected to tri-axial compression under strain controlled conditions while a constant confining pressure was maintained. Findings – The non-breakable particles showed a remarkable ability to dilate as a result of a higher inter-particle locking effect. Dilation forces the particles to move from a lower potential energy state to a higher potential energy state, which causes the micro-structure to become less stable, resulting in a dramatic decline in the angle of friction from the peak state to the residual state. In addition, the elongated particles enhance the interlocking effect, but breakage is also more likely to occur. The net effect of those two mechanisms controls the overall shearing resistance of rockfill materials. Originality/value – After calibration using a few micro-parameters, the combined FDEM was able to reproduce the typical behavior of rockfill materials without requiring a description of the complex relationship that exists between constituents; this relationship must be described in continuum mechanics. The simulation results showed that this approach is predictive. The combined FDEM also provides an opportunity for a quantitative study of the micro-structure of granular materials, and this study will help us to better understand the mechanical characteristics of rockfill materials. [ABSTRACT FROM AUTHOR]

A new process was developed to prepare a ceramic core with reasonable strength, and without shrinkage and shape deformation. In this work, a mixture of inorganic precursor composed of silicate and metal alkoxide was used to increase the strength of the core during the wax injection under about 50°C and the casting processes under about 1300–1350°C. In the case of the core prepared through the new process, the nominal fracture strength is 12MPa because of the glass phase synthesized by the inorganic precursor. However, in the conventional process, the core shows the strength of about 6MPa, as manifested by the sintering effect between starting particles occurring during heat treatment. In addition, the core sample prepared using the inorganic precursor is completely eluted in a sodium hydroxide solution, indicating that the new core process is reasonable for the fabrication of a ceramic core having high strength and crushability. [ABSTRACT FROM AUTHOR]

Mechanical characteristics (i.e., stiffness, internal friction angle, peak strength) and crushability of a soft granular material were evaluated by performing a comprehensive series of laboratory tests using the following devices: standard and non-standard triaxial apparatus, direct and annular shear box, oedometer and hydrostatic devices. The initial tested specimens differ by initial void ratio, grading characteristics and particle hardness. The air-dried specimen of soft particles were then subjected to monotonic loadings for various stress paths (direct and annular shear stress paths, oedometer stress paths until different upper normal pressures, triaxial stress paths including different confining pressures). After each homogeneous test, sieving has been performed in order to characterize the evolution of grading characteristics of the granular packing. Experimental results on mechanical properties show that maximum internal friction angle is rather independent of the particle stiffness even though small differences may exist before peak stress-state. As highlighted by recent studies (Arslan in Granul Matter 11(2): 87-97, ), the volumetric response of the specimen indicates that classical critical state is no more a relevant framework when particle crushability is too high compared with the applied stress-state. Crushability related to loading paths has been evaluated through the relative breakage ratio (B). The first results pointed out the effects of initial geometrical configuration (i.e., void ratio, grading) and particle stiffness. Analysis of the stress paths effects on the amount of breakage revealed that stress-state is not sufficient to describe properly breakage undergone by the material which is confirmed by an obvious link between volumetric strain and total breakage. Finally, the present study showed that the percentage of fine particles content during breakage may be seen as a function of the 'level' of deviatoric loading paths. [ABSTRACT FROM AUTHOR]

Abstract: An approach was developed for investigating the crushability behavior of epoxy-based, low-density structural polymeric foam (initial bulk density 0.81g/cm3 was used for test illustration) under quasistatic and high strain rate conditions in rigid confinement. Quasistatic crushability tests were conducted in a steel confinement cell using an MTS material testing system and the high strain rate (dynamic) crushability behavior was investigated by placing a foam specimen in a steel confinement tube and then loading the specimen using two different split Hopkinson pressure bar systems, namely, a magnesium bar and steel bar. The dynamic deformation characteristics were obtained using a multi-step incremental loading procedure. It was found that these foams exhibited large uniform inelastic deformation during the confined loading. It is verified that multi-step incremental loading can be used to construct the complete stress–strain response curve for the specimens under both quasistatic and dynamic loading conditions. A phenomenological constitutive model was then applied to parametrically describe the crushability response and to determine the rate sensitivity of the foams. The rate sensitivity of yield stress was found to be around three under rigid confinement. [Copyright &y& Elsevier]