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Calcite cement in an ooid-rich limestone; Carmel Formation, Jurassic of Utah. Minerals bond grains of sediment together by growing around them. This process is called cementation and is a part of the rock cycle. Cementation involves ions carried in groundwater chemically precipitating to form new crystalline material between sedimentary grains ...
Microbial induced calcium carbonate precipitation has been proposed as an alternative cementation technique to improve the properties of potentially liquefiable sand. [ 1 ] [ 18 ] [ 20 ] [ 21 ] [ 22 ] The increase in shear strength, confined compressive strength, stiffness and liquefaction resistance was reported due to calcium carbonate ...
Whether the initial cementation was concentric or pervasive, there is considerable evidence that it occurred quickly and at shallow depth of burial. [45] [46] [47] [38] In many cases, there is clear evidence that the initial concretion formed around some kind of organic nucleus. [48] The origin of the carbonate-rich septaria is still debated.
The exponent has been observed near 1.3 for unconsolidated sands, and is believed to increase with cementation. Common values for this cementation exponent for consolidated sandstones are 1.8 < < 2.0. In carbonate rocks, the cementation exponent shows higher variance due to strong diagenetic affinity and complex pore structures.
Compactions and cementation generally lead to permeability reduction by losing porosity. [1] When a large region, which consist a fault zone, experience compaction and cementation, porosity loss in host rock (undeformed rock surrounding the fault zone) can be greater than that of fault zone rock. Hence, fluids are forced to flow through a fault ...
Beachrock along Réunion island seashore Detail showing fragments of coral and shells. Beachrock is a friable to well-cemented sedimentary rock that consists of a variable mixture of gravel-, sand-, and silt-sized sediment that is cemented with carbonate minerals and has formed along a shoreline.
Soil sieve nests with dry soil aggregates after removal from a laboratory drying oven. Soil aggregate stability is a measure of the ability of soil aggregates—soil particles that bind together—to resist breaking apart when exposed to external forces such as water erosion and wind erosion, shrinking and swelling processes, and tillage.
In the presence of anionic groups such as sulfate, carbonate or chloride, AFm phases and AFt or ettringite phases can form. Pozzolanic reaction is a long term reaction, which involves dissolved silicic acid, water and CaO or Ca(OH) 2 or other pozzolans to form a strong cementation matrix. This process is often irreversible.