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1.
Correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from Turkey 总被引：3，自引：0，他引：3
Granitic rocks show a variety of engineering properties that may affect quarrying operations, tunneling, mining, slope stability and the use of rock as a construction material. The physical and mechanical properties are a function of the mineralogical and textural characteristics of the rock. The purpose of this study is to apply correlation analysis to investigate the relationships between petrographical and engineering properties of granitic rocks. A variety of granitic rock samples from different parts of Turkey were subjected to petrographic studies. The same samples were then tested to determine specific gravity, dry and saturated unit weight, water absorption, effective and total porosity, sonic velocity, Schmidt hardness, point load strength index, uniaxial compressive strength, tensile strength and modulus of elasticity. The relationships between these properties and the petrographical characteristics are described by simple regression analyses. The study revealed that the influence of the textural characteristics on the engineering properties appears to be more important than the mineralogy. It also determined that the types of contacts, grain (mineral) shape and size significantly influence the engineering properties of the granitic rocks. 相似文献
2.
The effect of weathering on pore geometry and compressive strength of selected rock types from Turkey 总被引：7，自引：0，他引：7
Atiye Tu
rul 《Engineering Geology》2004,75(3-4):215-227
Weathering processes cause important changes in rock porosity. Besides porosity, distribution of pore sizes is significant for the identification of changes due to rock weathering and its effects on fabric. The formation of secondary porosity in different types of rock taken from different parts of Turkey was examined and the results are presented in this paper. The aim of this study was to observe changes in porosity due to weathering. Effective porosity, mercury intrusion porosimetry, and optical and scanning electron microscopy were used to evaluate the changes in pore geometry of the rocks. Additionally, the dry density, water absorption and uniaxial compressive strength of the rocks at different weathering stages were determined. Analysis of experimental data showed that microstructure of the rocks in relation to weathering is the main feature, which controls their physical and mechanical properties. The study revealed that fabric characteristics, particularly the pore and fracture geometry are very important characteristics for assessment of the behaviour of weathered rock. 相似文献
3.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》1999,24(10):861-870
Weathering rates based on temporal changes in a variety of rock properties were examined for four dated lava domes made of porous rhyolite. The lava domes were erupted at 1.1, 2.6, 20 and 40 ka BP. The time from each eruptive event to the present provide elapsed weathering times. The lava domes have many cooling joints formed immediately after eruption. Joint-bounded blocks have a high porosity, resulting in deep weathering. The blocks have almost uniform characteristics from top to bottom in one outcrop. The mineralogical, chemical, physical and mechanical properties of the four rhyolites were analysed. These results show that the chemical properties and physical properties, including specific surface area, change slowly in the early stage of weathering (0–20,000 years) and quickly in the later stage (20,000–40,000 years), while mechanical strength and bulk density or porosity of the rhyolites change rapidly in the early stage and slowly in the later stage. Mechanical strength reduces by 70–90% relative to fresh rock in 40,000 years, although chemical and physical properties change by only 1023̄0 %. It is concluded that different weathering properties exhibit different rates and patterns of change over 40,000 years, and that mechanical strength is the property most susceptible to weathering. 相似文献
4.
Ten soils from Puerto Rico representing various states of weathering were subjected to engineering index tests, strength and density measurement, mineralogic analyses, and scanning electron microscopy.Engineering classification systems used for temperate soils tend to underestimate the engineering behavior of these undisturbed lateritic soils and in the undisturbed state the soils exhibit low densities and high strengths.The engineering properties of the undisturbed soils show systematic trends in relation to the degree of weathering and the parent rock. For a given rock, the void ratio is decreased and cohesion increased as weathering proceeds. This is the result of increasing crystallization and cementation by the sesquioxides.The specific gravity of the solid particles is a promising index property to characterize these lateritic soils insofar as it reflects iron oxide content. The decrease in void ratio and increase in cohesion with increasing specific gravity suggests a model for the engineering classification of tropical soils. 相似文献
5.
Most studies dealing with material properties of sandstones are based on a small data set. The present study utilizes petrographical and petrophysical data from 22 selected sandstones and ~300 sandstones from the literature to estimate/predict the material and weathering behaviour of characteristic sandstones. Composition and fabric properties were determined from detailed thin section analyses. Statistical methods applied consist of data distributions with whisker plots and linear regression with confidence regions for the petrophysical and weathering properties. To identify similarities between individual sandstones and to define groups of specific sandstone types, principal component and cluster analyses were applied. The results confirm an interaction between the composition, depositional environment, stratigraphic association and diagenesis, which leads to a particular material behaviour of sandstones. Three different types of pore radii distributions are observed, whereby each is derived from different pore space modifications during diagenesis and is associated with specific sandstone types: (1) bimodal with a maximum in capillary and micropores, (2) unimodal unequal with a maximum in smaller capillary pores and (3) unimodal equable with a maximum in larger capillary pores. Each distribution shows specific dependencies to water absorption, salt loading and hygric dilatation. The strength–porosity relationship shows dependence on the content of unstable lithic fragments, grain contact and type of pore radii distribution, cementation and degree of alteration. Sandstones showing a maximum of capillary pores and micropores (bimodal) exhibit a distinct hygric dilatation and low salt resistance. These sandstones are highly immature sublitharenites–litharenites, characterized by altered unstable rock fragments, which show pointed-elongated grain contacts, and some pseudomatrix. Quartz arenites and sublitharenites–litharenites which are strongly compacted and cemented, show unimodal unequal pore radii distributions, low porosity, high strength and a high salt resistance. The presence of swellable clay minerals in sublitharenites–litharenites leads to a medium to high hygric dilatation, whereas quartz arenites show little hygric dilatation. Sandstones with unimodal equal pore radii distribution mostly belong to weakly compacted and cemented mature quartz arenites. These are characterized by high water absorption and high porosity, low to medium strength and a low salt resistance. The data compiled in this study are used to create a sandstone quality catalogue. Since material properties are dependent on many different parameters of influence, the transition between different lithotypes is fluent. 相似文献
6.
The influence of petrophysical properties on the salt weathering of porous building rocks 总被引：1，自引：0，他引：1
D. Benavente N. Cueto J. Martínez-Martínez M. A. García del Cura J. C. Cañaveras 《Environmental Geology》2007,52(2):215-224
The influence of pore structure, water transport properties and rock strength on salt weathering is evaluated by means of
a thorough rock characterisation and a statistical analysis. The pore structure was described in terms of its porosity, pore
size distribution (quantified by mean pore radius) and specific surface area, density and water transport was characterised
by means of water permeability (saturated flow) and capillary imbibition (unsaturated flow); whilst the rock strength test
was carried out using uniaxial compressive strength, compressional and shear wave velocities, dynamic elastic constants and
waveform energy and attenuation were obtained from the digital analysis of the transmitted signal. A principal component analysis
and a stepwise multiple regression model was carried out in order to examine the direct relationships between salt weathering
and petrophysical properties. From the principal component analysis, two main components were obtained and assigned a petrophysical
meaning. The first component is mostly linked to mechanical properties, porosity and density whereas the second component
is associated with the water transport and pore structure. Salt weathering, quantified by the percentage of weight loss after
salt crystallisation, was included in both principal components, showing its dependence on their petrophysical properties.
The stepwise multiple regression analysis found that rock strength has a predominant statistical weight in the prediction
of salt weathering, with a minor contribution of water transport and pore structure parameters. 相似文献
7.
Salt crystallization is the most significant factor in the degradation of the natural stones used in cultural and historical structures. Stones decay partially or fully as a result of this exposure. This study is the investigation of the degradation of historical monuments (underground cities and semi-underground settlements) carved in pyroclastic rocks in Cappadocian Region which takes part in World Cultural Heritage List. Samples of pyroclastic rocks were collected from six different quarries in Cappadocia, Turkey. To understand the contribution of salt crystallization to this weathering, dry weight loss (DWL) tests were performed on these samples. To investigate the correlations between salt crystallization and other rock properties, porosity, water absorption, ultrasonic velocity, uniaxial compressive strength, Brazilian tensile strength, and point load index were also measured. During the SC process of weathering, the results showed that porosity and water absorption increased for all the samples whereas ultrasonic velocity, uniaxial compressive strength, tensile strength, and point load index values decreased. Evaluation of the data obtained from these tests showed very high logarithmic correlations between the dry weight loss values and the mechanical properties. 相似文献
8.
The results of the geological characterization of an old stone building in southern Italy, are presented here. The Mondragone marble is a slightly metamorphosed carbonate rock, which was widely employed as monumental stone in the 18th century Royal Palaces of Naples and Caserta. In this paper, for the first time, this rock has been investigated with a thorough laboratory testing program, aimed at defining its mineralogical, physical and mechanical parameters. The two most important varieties of Mondragone marble were separately tested: the yellow and grey marbles (hereafter, YM and GM, respectively). The results obtained from physical tests (open porosity, dry density, specific gravity, water absorption coefficients, ultrasonic velocity) did not show marked differences between the two materials; in contrast, the mechanical strength tests (uniaxial compressive strength, point load strength, flexural strength) showed better behaviour of YM than for GM. After a tentative comparison with other well known carbonate rocks from Italy, some considerations on the response of Mondragone marble to local weathering were conducted. In particular, the weathering typologies were related to the particular texture of the brecciated marble and the different strength resistances displayed by the various constituents of the rock. 相似文献
9.
A Moisture Index Classification System for Rocks (MiC System) 总被引：1，自引：0，他引：1
Summary. Interaction of rocks with water is leading to a reduction in physical and mechanical properties, and quantifying this effect
has always been a problem for design purposes in rock engineering projects. Despite the fact that a number of considerable
works have been carried out in this field, they are not thorough and general. In this paper, a new rock classification system
is presented in order to evaluate wet rock properties.
Laboratory studies showed that six parameters may be recognized as major controlling parameters for wet rocks, including:
water absorption, porosity, weathering degree, swelling index, number of microfissures, and average grain size. Many tests
were performed and a sensitivity analysis was carried out on the data obtained. This analysis characterized the rock sensitivity
when changing each parameter and consequently, a rating value was assigned to each parameter.
By adding these rating values, a rating between zero and 100 is allocated to each rock as Moisture index (Mi). The closer
this index is to 100, the more sensitive rock will be to moisture. On the basis of this index, rocks are divided into five
classes including: very good, good, fair, weak and very weak. 相似文献
10.
M. Ahmad M. K. Ansari Rajesh Singh L. K. Sharma T. N. Singh 《Geotechnical and Geological Engineering》2017,35(2):827-842
Weathering and durability are the key factors of the rock in the suitability and usefulness of different construction materials, building materials and engineering structures. A single test never predicts the entire factor for suitability of rock stone and aggregate in different uses. Thus, variety of physical, mechanical and chemical tests and indices of rocks are widely used to estimate and evaluate the rocks for the suitability of the required purpose. In all the cases, knowledge of durability and weathering properties are the most important along with the strength of the rock. Micropetrographic index and rock durability indicators (dynamic and static) are the one of the best methods to evaluate the rock for weathering and durability. To estimate these indices, variety of tests are performed such as petrographic examination test, point load index, sulfate soundness test, water absorption test, modified aggregate impact value test and test for specific gravity. Slake durability index and impact strength index tests were also performed for correlation with static and dynamic rock durability indicators due to its application and usefulness in the durability and strength of the rock materials. Micropetrographic index was obtained by petrographic examination test and correlated with all the physical and mechanical properties used for find out the durability indicators. The present study is to express the usefulness of these three indices in the classification of weathering and durability classes and estimation of durability indices by slake durability index, impact strength index and micropetrographic index. 相似文献
11.
The behaviour of consolidated volcanic tuffs: weathering mechanisms under simulated laboratory conditions 总被引：1，自引：0，他引：1
Five volcanic tuffs ranging from dacitic tuffs of Hungary to rhyolite, phonolite and basaltic tuffs of Germany were consolidated under laboratory conditions. Prior to consolidation an anti-hygro, a hydrous consolidant, which reduces the swelling ability of clay minerals, was applied. The three consolidants, a silicic acid ester (SAE), an elastic silicic acid ester (eSAE) and an acrylate resin (PMMA) were applied on test specimens under vacuum. Petrographic characterisation (polarizing microscopy, XRD, SEM) provided data for fabric analyses and the mineral composition of the tuffs. Changes in fabric, effective porosity, density, tensile strength, ultrasonic wave velocity were evaluated after the treatment. Weathering simulation tests such as hygric dilatation and thermal dilatation aimed to prove the effectiveness of consolidation and the durability of consolidated tuff samples. More than 500 samples were analysed. The tests showed that SAE caused the highest increase in indirect tensile strength. The water absorption and the pore size distribution of the tuffs were modified by consolidation. The PMMA reduced the water absorption the most, whereas SAE modified it the least. All the tested consolidants increased the thermal dilatation of the tuffs. The changes in hygric dilatation were not uniform: for most tuffs SAE increased and PMMA decreased the hygric dilatation, although the clay-rich Habichtswald tuff showed the opposite trend. The changes in hygric and thermal behaviour of consolidated tuff require special care when specific consolidants are chosen. These products modify the physical properties of consolidated tuffs and change the behaviour of weathering. 相似文献
12.
It has been recognized that there exists a serious need for recovery and reuse of industrial wastes. Agglomeration by pelletization method can alleviate the problems associated with fly ash. The objective of this study was to evaluate the material properties of manufactured aggregates produced from fly ash and cement mixing by pelletization method. Engineering properties of the manufactured aggregates were evaluated experimentally. Crushing strength, specific gravity, water absorption, particle size distribution, surface characteristics and shear strength properties of the manufactured aggregates were evaluated. For all practical purposes, the study showed that the manufactured aggregates are a good alternative for wide range civil engineering applications. 相似文献
13.
D. Benavente J. Martinez-Martinez N. Cueto S. Ordoñez M. A. Garcia-del-Cura 《Environmental Earth Sciences》2018,77(4):147
This study aims to understand the effect of salt and frost crystallisation on the petrophysical and durability properties of representative types of travertine and carbonate tufas. Results demonstrate that the studied travertines and tufas exhibit a very high durability against salt and ice crystallisation cycles, compared to carbonates rocks with similar porosity values. The variation of the loss of mass, effective porosity, capillary absorption coefficient, ultrasonic wave velocity and attenuation, and compressive strength was scarce during weathering tests. The evolution of petrophysical properties was slightly more intense after 30 cycles of salt crystallisation than 100 cycles of freeze–thaw. Petrophysical and durability properties of the travertines and carbonate tufas depend on porosity fraction and on the manner in which the vuggy porosity is connected. In the travertine facies, vuggy macropores show little connection and can be considered as separate-vug porosity. Their addition to interparticle porosity increases effective porosity and reduces their mechanical strength but does not significantly increase capillary transport and the effectiveness of salt and ice action over the stone. On the contrary, in the carbonate tufas, vugs act as touching-vug pores, as capillary imbibition coefficients reveal. However, scanning electron microscopy displays that they underwent microcracking processes related mainly to both thermal stresses and/or ice and salt pressures. These microcracks present little connection, and they do not enhance noticeably the water flow or decrease the mechanical properties. These results are finally discussed in terms of a nonlinear decay pattern, which with long periods of apparent stability might be followed by rapid and catastrophic decay. 相似文献
14.
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16.
I˙stanbul, the capital of the east Roman, Byzantine and Ottoman Empires embraces two continents, one arm reaching out to
Asia, the other to Europe. It is therefore, a rich city in terms of monuments and historical cites. Shell limestones of Upper
Miocene age are used as building stone in the majority of the monuments in I˙stanbul because of their attractiveness, availability
and workability. The durability characteristics of the limestones are examined, and those factors that are responsible for
atmospheric weathering are discussed, in a humid and marine environment with important problems of urban pollution, specifically
due to traffic. In the present study weathering of the building stones were first examined in situ by macroscopic observations.
The weathering that developed as a result of environmental effects since this limestone was first used in historical monuments
has been affected 0.1–1.5 cm deep from the surface. The weathered facing stone of Şehzade Mehmed Mosque in I˙stanbul is undergoing
a program of progressive replacement. During this study, samples were taken from this monument where the shell limestone was
used. The stone surface was principally examined by means of Scanning Electron Microscopy (SEM). Petrographical and mineralogical
analyses were made by using optical microscopy and X-ray diffraction method. The physico-chemical properties of these rocks
control their weathering behaviour and reactivity. Major and trace element analyses and the effect of deterioration on the
physical properties of the limestones (unit weight, porosity and water absorption) have also been investigated. Studies on
the samples implies that weathering on the stone surface caused important variations on the physical characteristics of the
rock.
Received: 11 February 1998 · Accepted: 18 August 1998 相似文献
17.
Wanja Wedekind Joerg Ruedrich Siegfried Siegesmund 《Environmental Earth Sciences》2011,63(7-8):1787-1798
In the Aztec period and in colonial times different natural stones originating in the Valley of Mexico were used for building construction. Stone weathering was investigated onsite at various historical buildings within the old quarter of Mexico City. In this study, different aspects of weathering and deterioration at three significant historical buildings will be presented, the Aztec excavation site Templo Mayor, the Metropolitan Cathedral, and the colonial palace of the dukes of Heras Soto. Petrophysical properties of the main building stones of these structures were investigated like density, porosity, pore radii distribution, water uptake rate and coefficient, thermal and hygric expansion, and the mechanical properties of uniaxial compressive strength. A relationship between single critical property values, according to anisotropy fabric characteristics, and specific weathering forms could be deduced. 相似文献
18.
Engineering classifications which are useful for “temperate” zone soils usually fail to predict the field performance of lateritic soils, because the index tests upon which the classifications are based are not always reproducible for lateritic soils. Undisturbed and disturbed samples of twelve lateritic soils from Hawaii and Puerto Rico, all derived from basalt but representing various stages of weathering were subjected to engineering and mineralogic tests. The specific gravity of the solids increases as the degree of weathering increases; and both strength and void ratio exhibit systematic trends with increased weathering. These results suggest a classification based upon specific gravity and void ratio. Soils with specific gravities less than 3.05 and void ratios greater than 1.25 have low cohesion (less than 20 psi) and low internal friction angles (less than 35°); whereas soils with void ratios between 1.25 and 0.9 have higher cohesions. Still greater values for cohesion and friction angles are noted in soils with void ratios lower than 0.9. Soils with specific gravities greater than 3.05 and void ratios greater than 1.25 have low cohesion but high friction angles. Thus by measuring the void ratio and specific gravity of these soils one can estimate their strength. 相似文献
19.
水与温度变化是工程岩石物理力学性能劣化的典型风化因素。对不同含水状态及经受不同次数冻融循环损伤后的红砂岩岩样进行了单轴压缩、劈裂拉伸及变角剪切试验。结果表明,红砂岩抗压强度、弹性模量、劈拉强度、黏聚力及内摩擦角等主要力学指标随含水率和冻融循环次数的增大均有不同程度的降低,但降低规律有所不同。水对岩石有明显的软化作用,冻融循环累积损伤显著。利用微观电镜扫描分析了不同含水率及冻融损伤后岩样微观结构的变化规律,认为吸水及冻融循环过程中水对红砂岩的软化表现为溶蚀作用与介质作用,温度变化的作用表现在热变形不协调和相变作用。提出了冻融循环作用下红砂岩力学特性衰减模型,并据此分析了各力学指标的衰减速率和半衰期。该研究结果对涉水岩石工程及寒区岩石工程具有一定的意义。 相似文献
20.
E. Molina Ballesteros J. García Talegón A. C. I?igo I?igo M. González Sánchez H. Herrero Fernández 《Environmental Earth Sciences》2011,64(7):1741-1754
Some physical properties (bulk and free porosity, pore size distribution), and the chemical composition and mass balance of
two deeply weathered profiles one developed on Hercynian granodiorite and the other on pre-Cambrian slates were studied. Hydric
and mercury porosimetry, nitrogen adsorption techniques, chemical analyses and XRD techniques were used. On granodiorite,
weathering has created increased porosity with a pore diameter <5 μm, whereas on slates the weathering has produced of ca.
1 μm in diameter. These pore sizes have played an important role in the weathering processes. Assuming that weathering preserves
volumes, except in the uppermost part of the profiles, it brought about a loss of matter of more than 12% (~300 kg/m3) on granodiorite and ca. 30% (~800 kg/m3) on slates. These changes are related to shifts in the mineralogical evolution, with the appearance of new 2:1 and 1:1 phyllosilicates
and Fe oxy-hydroxides as the main authigenic minerals. The release of matter, at least since the upper Neogene until the present,
has led to the lowering of relief in a more or less homogeneous way, giving rise to gentle hillsides and flat surfaces below
which the current river networks are incised. Porosity studies have the potential to explain several specific landforms as
well as affecting landscape development in general. 相似文献