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This porosity can range in size, from sub-micron to voids greater than 10 mm, depending on the casting. Casting defects caused by porosity can affect the part’s structural integrity, creating a failure point. Porosity can also prevent the part from being pressure tight. This will impact performance if the part is designed to hold gases or ...
Concrete sealers are applied to concrete to protect it from surface damage, corrosion, and staining. They either block the pores in the concrete to reduce absorption of water and salts or form an impermeable layer which prevents such materials from passing.
Porosity may take on several forms from interconnected micro-porosity, folds, and inclusions to macro porosity visible on the part surface. The end result of porosity is the creation of a leak path through the walls of a casting that prevents the part from holding pressure.
The concept of permeability is of importance in determining the flow characteristics of hydrocarbons in oil and gas reservoirs, [4] and of groundwater in aquifers. [5]For a rock to be considered as an exploitable hydrocarbon reservoir without stimulation, its permeability must be greater than approximately 100 md (depending on the nature of the hydrocarbon – gas reservoirs with lower ...
After an initial layer of calcite is formed on the crack walls and the surrounding concrete matrix becomes less rich in calcium ions, the transition to the so-called "diffusion-controlled crystal growth" occurs, which means that the Ca 2+ ions must diffuse through the concrete, and the CaCO 3 layer in order to reach the crack surface and ensure ...
where is the void ratio, is the porosity, V V is the volume of void-space (gases and liquids), V S is the volume of solids, and V T is the total (or bulk) volume. This figure is relevant in composites , in mining (particular with regard to the properties of tailings ), and in soil science .
Detail showing some of the causes of damp penetration. Structural dampness is the presence of unwanted moisture in the structure of a building, either the result of intrusion from outside or condensation from within the structure.
A slurry wall is a civil engineering technique used to build reinforced concrete walls in areas of soft earth close to open water, or with a high groundwater table. [1] This technique is typically used to build diaphragm (water-blocking) walls surrounding tunnels and open cuts, and to lay foundations .