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Fractal pores and particles of rocks and soils
Published in Xie Heping, Fractals in Rock Mechanics, 2020
It should be pointed out that the pore volume of some rocks is not a fractal. For example, the L2 value for some rocks is less than the average pore size (Krohn, 1988a). Fractal pores of rocks are associated with diagenesis. The structures including euhedral quartz overgrowths, druse quartz, calcite, dolomite, and clays which give rise to fractal properties are shown to be diagenetic in the number of the samples. Uniform authigenic minerals, such as calcite cement or quartz which are irregularly arranged are shown to have fractal distributions, whereas uniform crystals which are uniformly arranged do not generate a fractal (Krohn, 1988b). The fractal structures can be regarded as inhomogeneous distributions within the rock, particularly for sandstones. Sandstone formation involves burial of the sand grains, and compaction and alteration of the pore structure by the flow of fluids through the pore space. Such alteration involves crystal growth and nucleation on the pore surface. Recent studies show that the flow rate of fluid through the rock strongly influences the extent of mineral formation: a slow flow rate leads to a greatly reduced porosity and permeability. The rate of diagenesis, therefore, is a function of time (Thompson, et al., 1987).
Minerals, rocks, discontinuities and rock mass
Published in Ömer Aydan, Rock Mechanics and Rock Engineering, 2019
Sandstone is a sedimentary rock composed mainly of mineral or rock grains of sand size (0.062–2 mm). Most sandstone is composed of quartz and/or feldspar. Some sandstones are resistant to weathering, and they are porous. When sandstone contains roughly 60% quartz sand and 25% feldspar, it is called Arkose. If the percentage of quartz is greater than 95%, it is called either quartzite or quartzarenite.
Sediments and Sedimentary Rocks
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Sandstones are common and form in many different settings. In terrestrial (continental) environments, sand, which later becomes sandstone, can accumulate in river or lake bottoms, glacial outwash or alluvial fans, and deserts. In marine environments, sand typically accumulates in beaches, deltas, or offshore bars. Common sandstones are dominated by medium-sized grains of quartz, because quartz is the most common and stable product of weathering. But the definition of sandstone is based only on grain size, and there are different kinds of sandstones distinguished by their mineralogical compositions.
Predicting mechanical properties and ultimate shear strength of gypsum, limestone and sandstone rocks using Vipulanandan models
Published in Geomechanics and Geoengineering, 2020
Wael Mahmood, Ahmed Mohammed, Saman HamaHussein
Sandstone is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains (Vipulanandan and Mohammed 2018). Most sandstone is composed of quartz or feldspar because these are the most common minerals in the Earth’s crust. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite (Bucksch 2013).
Pavement smoothness of asphalt concrete overlays
Published in International Journal of Pavement Engineering, 2019
Yetkin Yildirim, Gökhan Saygili
Three types of course aggregates including siliceous gravel, sandstone and quartzite were used in the surface mixture design. Siliceous gravel is made mostly of quartz-rich sand and sandstone. It shows high thermal expansion. Sandstone is a sedimentary rock that has quartz-rich varieties and is cemented by silica or iron oxides (feldspar, calcite, or clay). Sandstone is mostly porous and permeable. Pore water pressure plays a significant role in the compressive strength and deformation characteristics. It can reduce the unconfined compressive strength by 30–60%. Sandstone is resistant to surface wearing. It shows variable toughness, hardness and durability, good crushed shape, and excellent chemical stability and surface characteristics. It has relatively low density of 2.54 g/cm3.
Sandstone Conservation of Polish Tomb Chapel and Its Effect on Microbial Diversity
Published in International Journal of Architectural Heritage, 2023
Joanna Świątczak, Agnieszka Kalwasińska, Piotr Niemcewicz, Marta Chylińska, Agata Ogińska, Maria Swiontek Brzezinska
Water promotes the development of microflora. The destructive effect of the water on historical objects made of the sandstone is mainly due to its high porosity. Sandstone is one of the most commonly used building materials in architecture. Sandstones were formed as a result of cementing sand grains. Depending on the type of binder, it is more or less sensitive to water. Sandstone from Szydłowice is a more sensitive to water sandstone type (water absorption at the level of 7%). The reason for it is its high porosity and the mixed binder presence, which includes the clay fraction. This promotes the accumulation of moisture in the stone, and thus the washing out of the binder and degradation of the stone (Szambelan 2021). Furthermore, water promotes microflora development.