The Role of Microstructure in the Physical Properties of Rock

McWilliams, J.R.

doi:10.1520/stp45141s

Cited by 5 publications

(6 citation statements)

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“…1. Location of the granites contemplated in this study (adapted from Serviços Geoló gicos de Portugal, 1992). properties and is responsible for the anisotropy found in many granites (McWilliams, 1966;Engelder and Plumb, 1984;Almeida et al, 1998). Furthermore, for certain studies (e.g., radionuclide migration through the brock matrixQ), the location of the cracks is of the utmost importance, since some minerals are capable of binding certain ions.…”

Section: Introductionmentioning

confidence: 99%

Influence of microfractures and porosity on the physico-mechanical properties and weathering of ornamental granites

Sousa

Río

Calleja

et al. 2005

Engineering Geology

304

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The purpose of this paper is to demonstrate the influence porosity and fissuration exert on the physico-mechanical properties and durability of nine Portuguese ornamental granites with different petrographical and physical characteristics. Scanning electron microscopy (SEM) allows the type of cracks (intergranular, intragranular and transgranular) to be identified. A microfracture index was calculated based on the collected data. This index is called linear crack density (LCD) and is defined by the number of cracks per length unit. The results reveal that intragranular cracks are the most frequent and represent between 62.9% and 82.3% of all the cracks observed. A physical weathering classification system based on linear crack density values of the studied granites is presented. The voids included in these types of rocks are predominantly microfractures and correlate closely with open porosity and linear crack density. Uniaxial compressive strength and P-wave velocity (V P ) appear to decrease as linear crack density increases, albeit with low correlation coefficients. This may be due to the fact that linear crack density does not take into account possible preferential crack orientation and both properties are strongly dependent on this preferential orientation. Other textural characteristics, such as grain size and preferential orientation of certain minerals, may contribute to these low correlation coefficients. In ageing tests, the salt crystallization test demonstrated greater material loss in granites with higher linear crack densities and thermal shock testing proved that thermal cracks have a greater influence on V P in rocks with lower linear crack densities. In light of the ageing tests results, precaution is recommended when using granites with effective porosities greater than 3% as dimension stone out-of-doors in polluted continental or marine areas. D

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Section: Introductionmentioning

confidence: 99%

Influence of microfractures and porosity on the physico-mechanical properties and weathering of ornamental granites

Sousa

Río

Calleja

et al. 2005

Engineering Geology

304

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“…In this rock, grains are arranged in interlocking pattern which results low porosity. Therefore, porosity in granite can be negligible except the presence of few micro-cracks and fractures in it (McWilliams, 1996;Tuğrul and Zarif, 1999;Sousa et al, 2005).…”

Section: Distribution Of Radium Content Radon Flux Rate and Radon Emmentioning

confidence: 99%

Importance of radon studies in rural areas and correlation of indoor radon level with radon inventory

Banerjee

Sengupta

2015

IJLR

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The measurement of indoor radon in villages is very important as 50% of the world populations live in villages, and rural houses normally have very low air exchange rates. This study has estimated the possible indoor radon level from five types of rocks, which are readily available to build houses in Eastern Singhbhum district of India. In the process to calculate this radon inventory, radium content and radon flux rate were measured in the selected rocks. Then calculated radon emanation factor was compared with the possible indoor radon concentration computed from the available air ventilation rate of typical Indian houses. It was found that granite generated low radon level and it can be a good alternative choice as building material instead of other regionally used rocks. This study also suggests that important geological parameters, which develop and increase porosity, can effectively increase radon inventory.

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“…Moreover, planes of weakness and subcrystal boundaries (e.g. K-feldspar albitization), as well as cleavage planes in feldspar, are all responsible for incipient microfractures which trigger mineral breakdown (Moss, 1966;McWilliams, 1966;Blatt, 1967;Lidstrom, 1968;Moss and Green, 1975;Lorimer, 1976;White, 1976;Irfan and Dearman, 1978;Baynes and Dearman, 1978;Sprunt and Nur, 1979;Slatt and Eyles, 1981;Heins, 1995). Stress fields depend on a complex web of factors, such as the bedrock (rigid in case of glacial environments and deformable in case of sediment beds) and strain types (shear, tensile etc.).…”

Section: Mechanical Disaggregation and Sediment Generationmentioning

confidence: 99%

“…Stress fields depend on a complex web of factors, such as the bedrock (rigid in case of glacial environments and deformable in case of sediment beds) and strain types (shear, tensile etc.). Simple shear produces abrasion (Boulton, 1978) whereas tensile stresses trigger mineral breakdown (McWilliams, 1966;Slatt and Eyles, 1981). Thus, in glacial environments, rock disaggregation may occur during grain collision, when the stress field is concentrated at the point of impact (breakdown), or when sand grains become trapped between gravel clasts (abrasion and grinding) (Harrell and Blatt, 1978).…”

Section: Mechanical Disaggregation and Sediment Generationmentioning

confidence: 99%

Influence of granitoid textural parameters on sediment composition: Implications for sediment generation

Caracciolo

Tolosana‐Delgado

Pera

et al. 2012

Sedimentary Geology

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The aim of this study is to determine and characterise the control exerted by parent rock texture on sand composition as a function of grain size. The sands investigated were generated from granitoid parent rocks by the Rhone, Damma and Sidelen glaciers, which drain the Aar Massif in the Central Alps (Switzerland), and were deposited in glacial and fluvio-glacial settings. Mechanical erosion, comminution (crystal breakdown and abrasion) and hydraulic sorting are the most important processes controlling the generation of sediments in this environment, whereas chemical and/or biochemical weathering plays a negligible role. By using a GIS-based Microscopic Information System (MIS), five samples from the glacier-drained portions of the Aar basement have been analysed to determine textural parameters such as modal composition, crystal size distribution and mineral interfaces (types and lengths). Petrographic data of analysed sands include traditional point counts (Gazzi-Dickinson method, minimum of 300 points) as well as textural counts to determine interface types, frequency, and polycrystallinity in phaneritic rock fragments. According to Pettijohn's classification, grain-size dependent compositions vary from feldspathic litharenite (0φ fraction) via lithic arkose (1φ and 2φ) to arkose (3φ and 4φ). Compositional differences among our data set were compared to modern plutoniclastic sands from the Iberian Massif (Spain) and the St. Gabriel Mts. (California, USA), which allowed us to assess the role exerted by glaciers in generating sediments. By combining data from the MIS with those from petrographic analysis, we outlined the evolution of mineral interfaces from the parent rocks to the sediments.

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The Role of Microstructure in the Physical Properties of Rock

Cited by 5 publications

References 0 publications

Influence of microfractures and porosity on the physico-mechanical properties and weathering of ornamental granites

Influence of microfractures and porosity on the physico-mechanical properties and weathering of ornamental granites

Importance of radon studies in rural areas and correlation of indoor radon level with radon inventory

Influence of granitoid textural parameters on sediment composition: Implications for sediment generation

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