air entrainment meaning

), Eur. Das Substantiv (Hauptwort, Namenwort) dient zur Benennung von Menschen, Tieren, Sachen u. Ä. ‘The many sophisticated experiments to study its physiology, entrainment, and the molecular mechanisms of feedback loops that exist in bacteria, as well as the clock-controlled genes are explored in detail.’ ‘A cement mix consists of Portland cement, aggregates, water, and air entrainment.’ The total flow increases, but the proportion of gases and the ratio stay the same, meaning then that the FIO 2 also remains the same. The mean kinetic energy, turbulent kinetic energy, potential energy and total energy were quantified with and without the void fraction being accounted for. Some common questions about air-entrained concrete are: does air entrainment reduce strength; does it affect the proportions of a concrete mixture; and can it be used in mild climates. in avalanche dynamics] Schneeaufnahme {f}meteo. Eventually the concrete spalls - chunks break off. Air-entrained concrete definition at Dictionary.com, a free online dictionary with pronunciation, synonyms and translation. Air entrainment during mould filling is major source of oxide inclusions in metal castings. Ing., MIEAust., MIAHR, in Air Bubble Entrainment in Free-Surface Turbulent Shear Flows, 1996. Watch Queue Queue. the transfer of air from the surrounding atmosphere into an organized air current:During a hurricane the temperatures in the upper atmosphere depend partly on the entrainment of drier or cooler air from outside the vortex. Mean air content . These air bubbles are dispersed throughout the hardened cement paste but are not, by definition, part of the paste (Dolch 1984). Meteorology. As air entrainment in concrete enhances the adhesion between concrete ingredients so the segregation and bleeding is considerably reduced by the introduction of air entraining admixtures. Air Entrainment. Definition of Air Entrainment in Construction. Some common questions about air-entrained concrete are: does air entrainment reduce strength; does it affect the proportions of a concrete mixture; and can it be used in mild climates. False Claims Act meets air entrainment Additionally, the main sources of oil contamination in wind turbines include solid particles, moisture, and entrained air . The air entrainment model offers the option to include buoyancy and bulking in the output, meaning that areas of variable density flows can be accurately represented. Find out the difference between beneficial air entrainment and accidental, or detrimental, air entrapment.. By Claude Goguen, P.E., LEED AP. The sand content will also be less by about 90 to 125 pounds per cubic yard. power or ability to act or to influence people, events, decisions, etc. Entrain definition: to board or put aboard a train | Meaning, pronunciation, translations and examples As mentioned above, anytime an emissions source is located within the vicinity of structures there is the possibility of re-entrainment. Air-entrained concrete contains billions of microscopic air cells per cubic foot. These air pockets relieve internal pressure on the concrete by providing tiny chambers for water to expand into when it freezes. Air-entraining admixtures are one part of the solution that will prevent damage from freeze-thaw conditions. The air bubbles formed in the fresh concrete act as a fluid, increasing its workability and allowing them to slide better with less friction. There are literally billions of these air bubbles in a single cubic foot of air-entrained concrete, and their presence dramatically changes the nature of both the fresh and hardened concrete. Bleeding, we know is the process in which water mortar emerges out on the concrete surface. The small, entrained air bubbles serve as reservoirs or expansion chambers to relieve these pressures. Air entraining was introduced in the 1930s and most modern concrete, especially if subjected to freezing temperatures, is air-entrained. These air pockets relieve internal pressure on the concrete by providing tiny chambers for water to expand into when it freezes. The air bubbles typically have a diameter of 10 to 500 micrometres (0.0004 to 0.02 in) and are closely spaced. The air entrainment in a free surface mainly results from the development of small turbulent structures in the air-water free surface, which have the capacity to trap air carrying it to the core of the flow. This is especially important when designing infrastructure for municipal water and wastewater transport, such as … During freeze-thaw cycles, the water occupying those pores expands and creates stresses which lead to tiny cracks. It is claimed that, the place-ability of an air entrained concrete having 7.5 cm slump is better than a non-air entrained concrete with a slump of 12.5 cm. A. im Singular (Einzahl) und Plural (Mehrzahl) auftreten. From: Coal Combustion Products (CCP's), 2017. The failure of reinforced concrete is most often due to this cycle, which is accelerated by moisture reaching the reinforcing steel. A model is developed to predict the location and rate of air entrainment as part of a standard mould filling simulation. These cracks allow more water into the concrete and the cracks enlarge. It also helps improve the workability of concrete. Commonly available masks deliver 24, 28, 31, 35, or 40 per cent oxygen. Air-Entraining Agent. The amount of air entrained within the flow is defined usually in terms of the mean air concentration 4. Entrain definition is - to draw along with or after oneself. ; The entrapment of gas bubbles or solid particulates in a flowing liquid, as with aeration. These tiny air pockets relieve internal pressure on the concrete by creating chambers for … Air-entraining admixtures facilitate the development of a stable air-void system within concrete that increases the durability of the concrete. Related terms: Air Entrainment; Binders; Compressive Strength; Water/Cement Ratio Fluid or Air Entrainment. The flow of 100 per cent oxygen through the mask draws in a controlled amount of room air (21 per cent oxygen). Air-entrained concrete is ordinary concrete that contains controlled amounts of air in the form of microscopic bubbles. Air can be entrained in concre t e by either of two methods: the use of air entraining agents or of air en-t r aining cements. A concrete maker introduces the bubbles by adding to the mix an air entraining agent, a surfactant(surface-active substance, a type of chemical that includes detergents). The air bubbles are created during mixing of the plastic (easy flowing, not hardened) concrete, and most of them survive to be part of the hardened concrete. In engineering, entrainment is the entrapment of one substance by another substance. Research has shown that the spacing and size of air bubbles are important in assuring their proper action. In regions where temperatures can frequently fluctuate near freezing, freeze-and-thaw cycles pose one of the greatest challenges to concrete durability. The air entrainment model is implemented in a casting simulation software validated by comparing its predictionsand to experimental air entrainment measurements for a circular water jet plunging into a quiescent liquid pool. Air entrainment is the intentional creation of tiny air bubbles in concrete. The mixing of air currents. The entrainment ratio represents a proportional relationship. Entrapped air is considered to not make a positive contribution to durability and is undesirable though not entirely avoidable. All air voids in concrete are not created equal. They range in size from a few thousandths of an inch in diameter to a few hundredths. Air entrainment, or free-surface aeration, is defined as the entrainment/entrapment of un-dissolved air bubbles and air pockets that are carried away within the flowing fluid. entrainment noun [U] (CARRYING) the process of making something part of a liquid or flow of something and carrying it along: Increased areas of open water are expected to improve aeration of lake water … As for the mix, it should be designed to take account for the increase in air content. Look it up now! How to use entrain in a sentence. Entrainment is a phenomenon of the atmosphere which occurs when a turbulent flow captures a non-turbulent flow. They range in size from a few thousandths of an inch in diameter to a few hundredths. Air entrainment is responsible for conferring extra plasticity to concrete mixtures. The bubbles contribute to workability by acting as a sort of lubricant for all the aggregates and large particles in a concrete mix. Air-entrained concrete contains billions of microscopic air cells per cubic foot. Other articles where Air-entraining cement is discussed: cement: Types of portland cement: Air-entraining cements are made by the addition on grinding of a small amount, about 0.05 percent, of an organic agent that causes the entrainment of very fine air bubbles in a concrete. Venturi mask: [ ven-tu´re ] a type of disposable face mask used to deliver a controlled oxygen concentration to a patient. It also is applied in the process of delivering aerosol treatments with medications. Air entrainment reduces the density of the mix and increases yield. For every 1% of additional air entrained, concrete strength will fall by around 5%. Commonly available masks deliver 24, 28, 31, 35, or 40 per cent oxygen. The importance of entrained air was first noticed during the 1930s, when certain highway sections were found to be more immune to the effects of freezing and thawing than others. The method of forming a small tiny bubble in the concrete is known as Air entrainment. (verb) Water beyond that is surplus and is used to make the plastic concrete more workable or easily flowing or less viscous . Using today's methods of entraining air, it is not difficult to obtain this bubble spacing. What does entrainment mean? For example: The entrapment of liquid droplets or solid particulates in a flowing gas, as with smoke. To be effective, bubbles must be spaced not more then .01 inches apart throughout the cement paste. The air bubbles are created during mixing of the plastic (easy flowing, not hardened) concrete, and most of them survive to be part of the hardened concrete. These intentionally entrained air bubbles are extremely small. This needs to be taken into account when batching and mixing. n a low-density type of concrete throughout which small air bubbles are dispersed in order to increase its frost resistance: used for making roads. Meaning of entrainment. The primary purpose of air entrainment is to increase the durability of the hardened concrete, especially in climates subject to freeze-thaw; the secondary purpose is to increase workability of the concrete while in a plastic state in concrete. Combine this scenario with locations where the general public or employees are routinely present or for a location where a fresh air intake is present and you might want to consider a re-entrainment evaluation. Without room for this expansion, large forces develop that can rupture the surface causing what is commonly called surface scaling. The strength of air-entrained concrete depends on the water/cement ratio as it does in non-air-entrained concrete. Air-entrained concrete is ordinary concrete that contains controlled amounts of air in the form of microscopic bubbles. The flow of 100 per cent oxygen through the mask draws in a controlled amount of room air (21 per cent oxygen). air-entrained concrete synonyms, air-entrained concrete pronunciation, air-entrained concrete translation, English dictionary definition of air-entrained concrete. Though hardened concrete appears solid, it is actually highly porous, having small capillaries resulting from the evaporation of water beyond that required for the hydration reaction. It is reported that, maximum flexural strength can be achieved even with air contant of 4%. 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