Testing long-term properties of aggregates requires time consuming laboratory tests. Alternatively, mathematical models can also be used to describe the abrasion process of aggregates. The paper uses ...another approach it links long-term abrasion to rock mechanical properties to facilitate a quick assessment of long term behavior of aggregates. It explores the long-term durability of aggregates through the application of long-term micro-Deval tests, extending the validity range of the relevant European standard (EN 1097-1:2012), that only requires 12,000 rotations for quality testing. Seven andesite lithotypes obtained from four Hungarian quarries were analyzed. The long-term micro-Deval coefficients were determined by increasing the number of rotations from the standardized 12,000 until the material loss reached the value of 99 m%. With some andesites, only 240,000 rotations were needed, while other ones required 2,000,000 rotations to a material loss of 80 m%. Regression analyses were used to find suitable models that describe the behaviour of the aggregates subjected to abrasion. The test results and the regression analyses supported previous studies suggesting that exponential functions are suitable to model abrasion. The abrasion model parameters introduced here were compared with the rock mechanical parameters of andesites and other lithotypes. It was found, that the newly introduced abrasion parameter A, which is a material-dependent empirical parameter, correlates with the ratio of the uniaxial compressive strength and water absorption. The introduction of the abrasion parameter provides an easy-to-use tool for the description of the behavior of aggregates exposed to natural or artificial abrasive effects. The knowledge of the abrasion process is essential for the lifetime analyses of crushed stones used as construction material or for the investigation of mass change of the grains in sedimentary systems such as riverbeds or coastal zones.
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•Extremely long-term durability tests; micro-Deval tests with hundreds of thousands/millions of rotations•Abrasion model of aggregates and wear of grains based on laboratory tests•A new abrasion parameter is introduced that describes the long-term durability of aggregates•Correlation between uniaxial compressive strength and aggregate durability of various rock types
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Particle density and water absorption may not always be sufficient to characterize the quality of RA.•Micro-Deval coefficient and Los Angeles coefficient of RA correlate well with mechanical ...properties of RAC.•Salt scaling, capillary absorption and bulk mortar’s porosity tended to be independent of RA quality.
Two physical properties of recycled aggregate (RA), namely oven-dried particle density (ρrd) and water absorption (WA24), are commonly used to characterize the quality of RA and to model the properties of recycled aggregate concrete (RAC). This approach suffers from several drawbacks, including high variability in WA24, overestimation of absorbed water due to the decomposition of hydrates during drying at (110 ± 5) °C, neglect of absorption kinetics, and insufficient consideration of old interfacial transition zone in RA. As an alternative, this study evaluates whether two mechanical properties of RA, namely micro-Deval coefficient (MDE) and Los Angeles coefficient (LA), can realistically describe the relationship between the properties of RA and RAC. Correlation analysis was conducted using data from this study and the literature. Results showed that the compressive strength, tensile splitting strength, modulus of elasticity and surface electrical resistivity of RAC varied in proportion to those four properties of RA, whilst the freeze-thaw resistance with de-icing salts, capillary absorption and bulk mortar’s porosity tended to be independent of RA quality. When estimating the mechanical properties of RAC, LA and MDE are valid indicators as alternatives to or simultaneously with ρrd and WA24.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
En canteras de la provincia de Buenos Aires, desarrolladas en el Sistema de Tandilia, grandes cantidades de rocas denominadas genéricamente como cuarcitas son removidas y acumuladas como pasivos ...ambientales, con el fin de explotar los estratos de arcillas infrayacentes. Considerando que la actividad minera de arcillas continúa en crecimiento, es necesario abordar debidamente esta problemática. La presente contribución expone los primeros estudios enfocados a caracterizar estas rocas cuarcíticas con el fin de incentivar su utilización como agregado grueso en obras viales. Los estudios petrográficos junto con los resultados obtenidos a partir del ensayo de desgaste Micro Deval (MD) permitieron definir cuatro variedades de cuarcitas. Las cuarcitas con mayor proporción de matriz (C1) tienen valores de desgaste mayores (coeficientes MD 24,6) que aquellas con mayor proporción de clastos de cuarzo (C2 y C3, coeficientes MD de 15,5 y 18,2, respectivamente). Por otro lado, el accionar de procesos de recristalización también podría haber influido en la mejor respuesta de estas rocas (C4). Si bien los coeficientes MD son aceptables a levemente por encima de los sugeridos para agregados gruesos de uso vial, se recomienda realizar mezclas que incluyan las diferentes variedades de cuarcitas con el fin de alcanzar valores admisibles en estos materiales.
En canteras de la provincia de Buenos Aires, desarrolladas en el Sistema de Tandilia, grandes cantidades de rocas denominadas genéricamente como cuarcitas son removidas y acumuladas como pasivos ...ambientales, con el fin de explotar los estratos de arcillas infrayacentes. Considerando que la actividad minera de arcillas continúa en crecimiento, es necesario abordar debidamente esta problemática. La presente contribución expone los primeros estudios enfocados a caracterizar estas rocas cuarcíticas con el fin de incentivar su utilización como agregado grueso en obras viales. Los estudios petrográficos junto con los resultados obtenidos a partir del ensayo de desgaste Micro Deval (MD) permitieron definir cuatro variedades de cuarcitas. Las cuarcitas con mayor proporción de matriz (C1) tienen valores de desgaste mayores (coeficientes MD 24,6) que aquellas con mayor proporción de clastos de cuarzo (C2 y C3, coeficientes MD de 15,5 y 18,2, respectivamente). Por otro lado, el accionar de procesos de recristalización también podría haber influido en la mejor respuesta de estas rocas (C4). Si bien los coeficientes MD son aceptables a levemente por encima de los sugeridos para agregados gruesos de uso vial, se recomienda realizar mezclas que incluyan las diferentes variedades de cuarcitas con el fin de alcanzar valores admisibles en estos materiales.
En canteras de la provincia de Buenos Aires, desarrolladas en el Sistema de Tandilia, grandes cantidades de rocas denominadas genéricamente como cuarcitas son removidas y acumuladas como pasivos ...ambientales, con el fin de explotar los estratos de arcillas infrayacentes. Considerando que la actividad minera de arcillas continúa en crecimiento, es necesario abordar debidamente esta problemática. La presente contribución expone los primeros estudios enfocados a caracterizar estas rocas cuarcíticas con el fin de incentivar su utilización como agregado grueso en obras viales. Los estudios petrográficos junto con los resultados obtenidos a partir del ensayo de desgaste Micro Deval (MD) permitieron definir cuatro variedades de cuarcitas. Las cuarcitas con mayor proporción de matriz (C1) tienen valores de desgaste mayores (coeficientes MD 24,6) que aquellas con mayor proporción de clastos de cuarzo (C2 y C3, coeficientes MD de 15,5 y 18,2, respectivamente). Por otro lado, el accionar de procesos de recristalización también podría haber influido en la mejor respuesta de estas rocas (C4). Si bien los coeficientes MD son aceptables a levemente por encima de los sugeridos para agregados gruesos de uso vial, se recomienda realizar mezclas que incluyan las diferentes variedades de cuarcitas con el fin de alcanzar valores admisibles en estos materiales.
Hydrophobized sands can be used to control infiltration as barriers in ground infrastructure. As coated granular materials, the interaction between particles is assumed to damage the coatings leading ...to a reduction in hydrophobicity. This study provides an insight into the physical degradation of hydrophobized sands treated with Tung oil, heated Tung oil and dimethyldichlorosilane. The Micro-Deval test is proposed and used for the first time to assess the degradation of the hydrophobized sands. The testing programme investigates the effect of the Micro-Deval testing conditions (number of revolutions and pore fluid or medium – dry/wet) and hydrophobicity (concentration and type of hydrophobic compounds) on the particle degradation and hydrophobicity degradation. Overall, this study demonstrated the effectiveness of the new methodology to investigate the physical degradation of hydrophobized sands, with the Micro-Deval test able to provide a rapid assessment of various hydrophobized sands under a range of conditions.
•Sands can be hydrophobized by dimethyldichlorosilane and (heated) Tung oil.•Abrasion of the sands performed with a Micro-Deval apparatus.•Results revealed a decreased particle size and hydrophobicity due to abrasion.•Size and hydrophobicity changes depend on hydrophobizing treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The objective of this study was to evaluate, comparatively, the evolution of this degradation of three rock types, two granitoids and a microgabbro which, eventually, could be used as ballast, due to ...the proximity of the quarries to the design route of a railroad to be built between São Paulo and around Campinas, State of São Paulo, southeastern Brazil. They were tested for alterability in sodium sulfate and ethylene glycol solutions. Based on detailed petrographic analysis, Micro-Deval and Slake Durability Index tests were performed with and without conjugation to the referred alterability tests. The results obtained are punctual, valid and positive for the samples of the rock masses carefully selected and described, considering the different characteristics of the granitoids belonging to the Morungaba and Cantareira Complexes. In the case of basic rock, the microgabbro, should not be used as ballast in the studied tropical climate area, since the exposed fragments that make up the ballast are intensely affected by chemical weathering (notably reactions accelerated by water and temperature), which culminate in the decomposition of primary minerals and, consequently, in the faster physical-mechanical degradation of this rock. In practice, more frequent periodic maintenance and higher costs.
Aggregate is one of the most widely used construction material. The quality of the aggregate is determined using some testing methods. Among these methods, the Micro Deval Abrasion Loss (MDAL) test ...is commonly used for the determination of the quality and the abrasion resistance of aggregate. The main objective of this study is to develop models for the prediction of MDAL from rock properties, including uniaxial compressive strength, Brazilian tensile strength, point load index, Schmidt rebound hardness, apparent porosity, void ratio Cerchar abrasivity index and Bohme abrasion test are examined. Additionally, the MDAL is modeled using simple regression analysis and multiple linear regression analysis based on the rock properties. The study shows that the MDAL decreases with the increase of uniaxial compressive strength, Brazilian tensile strength, point load index, Schmidt rebound hardness and Cerchar abrasivity index. It is also concluded that the MDAL increases with the increase of apparent porosity, void ratio and Bohme abrasion test. The modeling results show that the models based on Bohme abrasion test and L type Schmidt rebound hardness give the better forecasting performances for the MDAL. More models, including the uniaxial compressive strength, the apparent porosity and Cerchar abrasivity index, are developed for the rapid estimation of the MDAL of the rocks. The developed models were verified by statistical tests. Additionally, it can be stated that the proposed models can be used as a forecasting for aggregate quality.
•Effects of rock properties on the Micro Deval abrasion loss are studied.•The Micro Deval abrasion loss was modeled using regression analysis.•The prediction models of Micro Deval abrasion loss are proposed.•This study indicated that Bohme abrasion test is recommended for better prediction of the Micro Deval abrasion loss.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Rock aggregates constitute the enormous volume of inert construction material used around the globe. The petrologic description as igneous, sedimentary, and metamorphic types establishes the ...intrinsic formation pattern of the parent rock. The engineering properties of these rocks vary due to the differences in the transformation process (e.g. hydrothermal deposits) and weathering effect. The two most common mechanical tests used to investigate the performance of aggregates are the Los Angeles (LA) and micro-Deval (MD) tests. This study reviewed the geological parameters (including mineralogy, grain and crystal size, grain shape, and porosity) and the relationship to Los Angeles and micro-Deval tests. It was found that high content of primary minerals in rocks (e.g. quartz and feldspar) is a significant parameter for performance evaluation. Traces of secondary and accessory minerals also affect the performance of rocks, although in many cases it is based on the percentage. Furthermore, some studies showed that the effect of mineralogic composition on mechanical strength is not sufficient to draw final conclusions of mechanical performance; therefore, the impact of other textural characteristics should be considered. The disposition of grain size and crystal size (e.g. as result of lithification) showed that rocks composed of fine-grain textural composition of ≤ 1 mm enhanced fragmentation and wear resistance than medium and coarse grained (≥ 1 mm). The effect of grain shape was based on convex and concave shapes and flat and elongated apexes of tested samples. The equidimensional form descriptor of rocks somehow improved resistance to impact from LA than highly flat and elongated particles. Lastly, the distribution of pore space investigated by means of the saturation method mostly showed moderate (
R
= 0.50) to strong (
R
= 0.90) and positive correlations to LA and MD tests.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Micro-deval test provides a measure of resistance and durability of aggregates submerged in water through the actions of aggregate particles and abrasion from steel balls. The presence of water in ...the test chamber provides a more realistic assessment of field conditions when compared with Los Angeles (LA) abrasion test. Currently there is only one testing procedure in the United States (U.S.) to evaluate the coarse aggregates using micro-deval tests. Previous studies indicate that there has been significant interest in utilizing micro-deval test to assess the suitability coarse aggregates to be used in asphalt concrete and their field performance. However the studies related to evaluating coarse aggregates with micro-deval test for base course applications are very limited. This study attempts to address how the micro-deval testing procedure may be revised to better assess the performance of aggregates considered for the base course. Aggregates with seven different geological compositions were used in the study. Total of 250 micro-deval tests were performed and the results confirmed the repeatability and the suitability of the proposed method to all of the tested aggregates. As part of this study, a threshold is determined for the optimum amount of abrasive charge that should be used in the tests to obtain maximum material loss regardless of the geological make-up of the aggregate. If this approach is followed, a strong relationship between the number of revolutions and percent material loss is achieved. This relationship provides an opportunity to shorten the micro-deval tests and also an approach to assess durability of aggregates at number of revolutions significantly larger than what is prescribed in the existing micro-deval testing procedure. This ability may be used in the future to more realistically relate the long-term durability prediction of aggregates as it relates to field performance of base course.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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