scholarly journals Review of the relationship between aggregates geology and Los Angeles and micro-Deval tests

2021 ◽  
Vol 80 (3) ◽  
pp. 1963-1980
Author(s):  
Solomon Adomako ◽  
Christian John Engelsen ◽  
Rein Terje Thorstensen ◽  
Diego Maria Barbieri
Keyword(s):  
Los Angeles ◽  
Crystal Size ◽  
Grain Shape ◽  
Mechanical Performance ◽  
Pore Space ◽  
Construction Material ◽  
Engineering Properties ◽  
Coarse Grained ◽  
The Impact ◽  
The Relationship

AbstractRock 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.

scholarly journals The Impact of Secondary Phyllosilicate Minerals on the Engineering Properties of Various Igneous Aggregates from Greece

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 329 ◽  
Author(s):  
Petros Petrounias ◽  
Panagiota Giannakopoulou ◽  
Aikaterini Rogkala ◽  
Paraskevi Lampropoulou ◽  
Eleni Koutsopoulou ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Los Angeles ◽  
Moisture Content ◽  
Total Porosity ◽  
Physicomechanical Properties ◽  
Engineering Properties ◽  
Petrographic Analysis ◽  
Rock Samples ◽  
Los Angeles Abrasion ◽  
The Impact

This paper investigates the effect of alteration on the physicomechanical properties of igneous rocks used as aggregates, from various areas from Greece. The studied lithologies include serpentinized dunites, serpentinized harzburgites, serpentinized lherzolites, metamorphic gabbros, diabases, dacites and andesites. Quantitative petrographic analysis shows that the tested samples display various percentages of secondary phyllosilicate minerals. Mineral quantification of the studied rock samples was performed by using the Rietveld method on X-ray diffraction patterns. The samples were also tested to assign moisture content (w (%)), total porosity (nt (%)), uniaxial compressive strength (UCS (MPa)) and Los Angeles abrasion test (LA (%)). The influence of secondary phyllosilicate minerals on the physicomechanical behavior of the tested samples was determined using regression analysis and their derived equations. Regression analysis shows a positive relationship between the percentage of the phyllosilicate minerals of the rocks and the moisture content as well as with the total porosity values. In mafic and ultramafic rock samples, the relationships between the secondary phyllosilicate minerals and their physicomechanical properties have shown that the total amount of the secondary phyllosilicate minerals results negatively on their physicomechanical properties. On the other hand, the low percentage of phyllosilicate minerals in volcanic rocks can’t be able to define their engineering properties.

scholarly journals Development of Methods to Improve the Mechanical Performance of Coated Grid-Like Non-Crimp Fabrics for Construction Applications

2019 ◽  
Vol 27 (1(133)) ◽  
pp. 51-58 ◽  
Author(s):  
Lars Hahn ◽  
Steffen Rittner ◽  
Dominik Nuss ◽  
Moniruddoza Ashir ◽  
Chokri Cherif
Keyword(s):  
Tensile Strength ◽  
Mechanical Performance ◽  
Coating Process ◽  
Ultrasonic Vibrations ◽  
Coating Agent ◽  
Industry Standard ◽  
Machine Setting ◽  
The Impact ◽  
The Relationship ◽  
Setting Parameters

This paper presents investigations aiming to improve the impregnation of a coating agent and thus increase the mechanical performance of geogrids, especially grid-like non-crimp fabrics (NCF) consisting of carbon fiber heavy tows (CFHT). The squeezing process is industry standard, but the relationship between the machine setting parameters (squeezing pressure and hardness of squeeze roll surface) and the impact on the tensile strength of grid-like NCF is still unexplored. The setting parameters evaluated lead to an increase in tensile strength of up to 10% compared to grid-like NCF coated without the squeezing process. Additionally the first insights into the coating process supported by ultrasonic vibrations based on CFHT single yarns are provided. It is shown that the tensile strength of treated CFHT can be increased by up to 12%, in comparison to CFHT coated without ultrasonic vibrations.

Spatial spillover effects of crime on private investment at nearby micro-places

Urban Studies ◽  
2021 ◽  
pp. 004209802110297
Author(s):  
Arthur Acolin ◽  
Rebecca J. Walter ◽  
Marie Skubak Tilyer ◽  
Johanna Lacoe ◽  
Raphael Bostic
Keyword(s):  
New York ◽  
Los Angeles ◽  
San Antonio ◽  
Criminal Activity ◽  
Private Investment ◽  
Spillover Effects ◽  
Building Permit ◽  
Crime Trend ◽  
The Impact ◽  
The Relationship

Criminal activity may influence the decisions of existing property owners or prospective investors to invest in a property, given the potential elevated expenses and increased uncertainty that often accompany crime. This study investigates the relationship between crime and private investment at nearby micro-places using location-specific crime incident and building permit data from 2008 to 2018 in the cities of Chicago, Los Angeles, New York, Philadelphia, San Antonio and Seattle. Data were aggregated to the blockface-level to examine how changes in investment on a blockface are influenced by changes in crime on that blockface and adjacent blockfaces in the subsequent year. Results indicate that an increase in total crime on a blockface was associated with a significant decrease in building permit activity the following year in all six cities, but the relationship is less strong when aggregating crime from adjacent blockfaces. When looking at spillover effects, higher crime on adjacent blockfaces was significantly associated with lower levels of investment beyond the effect of the crime trend on that blockface in Los Angeles and San Antonio. Though the relationship between adjacent blockface crime and investment was negative across the other four cities, it was not statistically significant. Taken together, these findings suggest that effective targeted crime prevention policies may have the added benefit of spurring local economic investment and that the impact of crime is very localised.

The Impact of Structural Disadvantage on the Gender-Gap and Sex-Specific Rates of Nonlethal Violent Victimization

2017 ◽  
Vol 64 (2) ◽  
pp. 201-226 ◽  
Author(s):  
Ráchael A. Powers ◽  
Alyssa W. Chamberlain ◽  
Lyndsay N. Boggess
Keyword(s):  
Los Angeles ◽  
Gender Gap ◽  
Economic Inequality ◽  
Differential Susceptibility ◽  
Violent Victimization ◽  
Structural Disadvantage ◽  
Crime Type ◽  
The Impact ◽  
The Relationship ◽  
The City

This study examined the gendered impact of structural disadvantage and economic inequality on two forms of nonlethal victimization (assault and robbery). Compared with research on the gendered impact of structural disadvantage on perpetration, few studies have examined the differential susceptibility of men and women’s risk of victimization. We use data from the City of Los Angeles (2001-2007) to examine the relative influence of neighborhood characteristics on both the gender gap in victimization as well as sex-specific measures of assault and robbery victimization. In general, we largely find that neighborhood disadvantage and economic inequality do little to explain the gender gap in victimization; however, structure plays a more significant role in understanding sex-specific victimization rates, but the relationship varies by crime type.

Calculation of ceramic pot filter hydraulic conductivity using falling-head data

2011 ◽  
Vol 11 (3) ◽  
pp. 358-363 ◽  
Author(s):  
A. C. Elmore ◽  
W. G. Fahrenholtz ◽  
L. G. Glauber ◽  
A. N. Sperber
Keyword(s):  
Hydraulic Conductivity ◽  
Open Porosity ◽  
Production Efficiency ◽  
Lower Cost ◽  
Pore Space ◽  
Porous Media Equations ◽  
Side Walls ◽  
Flow Through ◽  
The Impact ◽  
The Relationship

Flowrate is used as a predictor of ceramic pot filter (CPF) disinfection effectiveness, and the relationship between flowrate and porosity has been examined in several studies. However, hydraulic conductivity, not porosity, is the constant of proportionality that describes flow through porous media. Equations have been developed to estimate the hydraulic conductivity of CPF side walls and bottom as well an effective overall hydraulic conductivity. The equations are intended to be used with falling head data that may be collected in the field. The results of flowrate testing and open porosity testing using experimental CPFs provide preliminary indication that hydraulic conductivity is a better predictor of flowrate relative to open porosity. The results of the preliminary testing suggest that the shape and orientation of open pore space may have significant impact on filter flowrates, and that filter researchers and producers may want to evaluate the material used to form the pores as well as the impact of the filter formation process on any spatial orientation of open pore space. A better understanding of hydraulic conductivity may improve the production efficiency of filter factories which could make lower cost filters available to a greater number of households in developing areas.

scholarly journals From System Modeling to System Analysis: The Impact of Resolution Level and Resolution Distribution in the Computer-Aided Investigation of Biomolecules

2021 ◽  
Vol 8 ◽  
Author(s):  
Marco Giulini ◽  
Marta Rigoli ◽  
Giovanni Mattiotti ◽  
Roberto Menichetti ◽  
Thomas Tarenzi ◽  
...  
Keyword(s):  
System Analysis ◽  
System Modeling ◽  
Coarse Grained ◽  
Detailed Model ◽  
Computer Aided ◽  
Resolution Level ◽  
The One ◽  
Improved Accuracy ◽  
The Impact ◽  
The Relationship

The ever increasing computer power, together with the improved accuracy of atomistic force fields, enables researchers to investigate biological systems at the molecular level with remarkable detail. However, the relevant length and time scales of many processes of interest are still hardly within reach even for state-of-the-art hardware, thus leaving important questions often unanswered. The computer-aided investigation of many biological physics problems thus largely benefits from the usage of coarse-grained models, that is, simplified representations of a molecule at a level of resolution that is lower than atomistic. A plethora of coarse-grained models have been developed, which differ most notably in their granularity; this latter aspect determines one of the crucial open issues in the field, i.e. the identification of an optimal degree of coarsening, which enables the greatest simplification at the expenses of the smallest information loss. In this review, we present the problem of coarse-grained modeling in biophysics from the viewpoint of system representation and information content. In particular, we discuss two distinct yet complementary aspects of protein modeling: on the one hand, the relationship between the resolution of a model and its capacity of accurately reproducing the properties of interest; on the other hand, the possibility of employing a lower resolution description of a detailed model to extract simple, useful, and intelligible information from the latter.

scholarly journals Some observations considering undrained shear strength, liquidity index, and fluid/solid ratio of mono-mineralic clays with water–ethanol mixtures

2018 ◽  
Vol 55 (7) ◽  
pp. 1048-1053 ◽  
Author(s):  
Giovanni Spagnoli ◽  
Helge Stanjek ◽  
Asuri Sridharan
Keyword(s):  
Pore Space ◽  
Regression Line ◽  
Liquid Limit ◽  
Particle Interactions ◽  
Solid Ratio ◽  
Liquidity Index ◽  
The Impact ◽  
First Time ◽  
The Relationship ◽  
Undrained Shear

The mechanical properties of clays are influenced by the characteristics of the fluid in the pore space. The liquid limit reacts differently to the permittivity, ε, of the fluid: for smectites the slopes are positive, for kaolinite and illite they are negative and smaller. This dissimilarity can be explained by the structural differences between swelling smectites with solvated interlayer cations and nonswelling clay minerals such as kaolinite and illite. Undrained shear strengths, cu, of Ca–smectite, but not Na–smectite, correlate with the actual fluid ratio. Regressing cu against the liquidity index, IL, yields two different regression lines for Na–smectite and Ca–smectite. For the first time it is shown that normalizing cu to the ε of the pore fluid results in a single regression line for both smectitic clay types. As kaolinites and illites possess significantly less exchangeable cations than smectites, this yields significantly smaller ranges for Atterberg limits and reduces the impact of ε on almost pure particle–particle interactions. In addition, the much larger particle sizes of the kaolinite and illite may dominate the undrained shear strengths, as normalization of cu to ε did not change the relationship to either the actual water content or the liquidity index.

scholarly journals The Impact of Secondary Phyllosilicate Minerals on the Engineering Properties of Various Igneous Aggregates from Greece

2018 ◽  
Author(s):  
Petros Petrounias ◽  
Panagiota P. Giannakopoulou ◽  
Aikaterini Rogkala ◽  
Paraskevi Lampropoulou ◽  
Eleni Koutsopoulou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Regression Analysis ◽  
Los Angeles ◽  
Moisture Content ◽  
Rietveld Method ◽  
Total Porosity ◽  
Engineering Properties ◽  
Petrographic Analysis ◽  
Los Angeles Abrasion ◽  
The Impact

This paper investigates the effect of alteration on the physicomechanical properties of igneous rocks from various areas from Greece used as aggregates. The studied lithologies include dunites, harzburgites, lherzolites, gabbros, diabases, dacites and andesites. Quantitative petrographic analysis shows that the tested samples display various percentages of secondary phyllosilicate minerals. Mineral quantification of studied rock samples was performed by using a Rietveld method on X-Ray diffraction patterns of the studied aggregates. The aggregates are also tested to assign moisture content [w (%)], total porosity [nt (%)], uniaxial compressive strength [UCS (MPa)] and Los Angeles abrasion test [LA (%)]. The influence of secondary phyllosilicate minerals on physicomechanical behavior of tested samples determined using regression analysis and their derived equations. Regression analysis shows positive relationship between the percentage of phyllosilicate minerals of rocks and moisture content as well as with the total porosity values. The relationships between phyllosilicate minerals in the ultramafic and mafic samples and their mechanical properties show that the total rates of phyllosilicate mineral products result negatively in their mechanical properties, while the low percentage of phyllosilicate minerals in volcanic rocks are not able to define set of their engineering parameters.

scholarly journals Textural Implications in Assessment of Physico-Mechanical behaviour of Metavolcanic Rocks from Dir Upper, north western Pakistan

2020 ◽  
Vol 11 (3) ◽  
pp. 1-10
Author(s):  
Muhammad Sajid ◽  
Muhammad Yaseen ◽  
Muhammad Zeeshan Ullah ◽  
Ghulam Murtaza
Keyword(s):  
Mechanical Properties ◽  
Los Angeles ◽  
Coarse Grained ◽  
Fine Grained ◽  
Rock Fragments ◽  
Metavolcanic Rocks ◽  
Permissible Range ◽  
Mineral Alteration ◽  
The Relationship ◽  
Western Portion

The Dir-Utror meta-volcanics from the south western portion of the Kohistan arc in northern Pakistan areanalyzed in term of their petrography, physico-mechanical properties. Field observations and petrography show thecollected representative samples to be fine-grained meta-andesites (FMA), coarse-grained meta-andesites (CMA) andagglomerate (AG). The relationship between petrography and physico-mechanical properties has been investigatedwhich inferred the grain size to be the major factor, alongside grains’ shape, arrangement and size distribution as wellas degree of mineral alteration significantly affecting the mechanical behavior of rocks. The CMA yield more strength(98 MPa) than FMA (93 MPa) due to its lesser degree of mineral alteration, inequigranular texture, lack of preferredmineral alignment, relatively low porosity and water absorption. The lower strength of agglomerate (57 MPa)corresponds to abundance of soft minerals (calcite), exotic rock fragments and coarse-grained texture. Based onphysico-mechanical properties including specific gravity, bulk density, aggregate impact value, Los Angeles abrasionvalue and unconfined compressive strength (UCS), these rocks fall within permissible range to be utilized for multipleengineering purposes including dimension stones and foundation materials for other civil structures. However,petrographic investigations reveal excessive amount of reactive silica in these rocks making them prone to alkali-silicareactivity in concrete works with ordinary Portland cement (OPC). Hence these rocks are not recommended for use assole aggregate material or low-alkali cement is recommended, if used.

scholarly journals The impact of diagenesis on the reservoir quality of the early Cretaceous Lower Goru sandstones in the Lower Indus Basin, Pakistan

2021 ◽  
Author(s):  
Qamar UZ Zaman Dar ◽  
Renhai Pu ◽  
Christopher Baiyegunhi ◽  
Ghulam Shabeer ◽  
Rana Imran Ali ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Pore Space ◽  
Hydrocarbon Exploration ◽  
Indus Basin ◽  
Coarse Grained ◽  
Rock Properties ◽  
Reservoir Properties ◽  
Diagenetic Processes ◽  
Lower Indus Basin ◽  
The Impact

AbstractThe sandstone units of the Early Cretaceous Lower Goru Formation are significant reservoir for gas, oil, and condensates in the Lower Indus Basin of Pakistan. Even though these sandstones are significant reservoir rocks for hydrocarbon exploration, the diagenetic controls on the reservoir properties of the sandstones are poorly documented. For effective exploration, production, and appraisal of a promising reservoir, the diagenesis and reservoir properties must be comprehensively analyzed first. For this study, core samples from depths of more than 3100 m from the KD-01 well within the central division of the basin have been studied. These sandstones were analyzed using petrographic, X-ray diffraction, and scanning electron microscopic analyses to unravel diagenetic impacts on reservoir properties of the sandstone. Medium to coarse-grained and well-sorted sandstone have been identified during petrographic study. The sandstone are categorized as arkose and lithic arkose. Principal diagenetic events which have resulted in changing the primary characters of the sandstones are compaction, cementation, dissolution, and mineral replacement. The observed diagenetic processes can be grouped into early, burial, and late diagenesis. Chlorite is the dominant diagenetic constituent that occurs as rims, coatings, and replacing grains. The early phase of coating of authigenic chlorite has preserved the primary porosity. The recrystallization of chlorite into chamosite has massively reduced the original pore space because of its bridging structure. The current study reveals that diagenetic processes have altered the original rock properties and reservoir characteristics of the Lower Goru sandstone. These preliminary outcomes of this study have great potential to improve the understanding of diagenetic process and their impact on reservoir properties of the Lower Goru sandstone in the Lower Indus Basin and adjoining areas.

Sign in / Sign up

Export Citation Format

Share Document