Fly Ash • As the surface area (fineness) of the fly ash increases, the amount of entrained air is decreased. Air entrainment also reduces the shelf-life of concrete. Flat particlesc. The risks associated with this requirement include: 1) increased probability of delamination or blistering; 2) reduction in surface air content; and 3) change in hardened air void parameters. For example, in the U.S., air entrained concrete specifications should be clearly written and comply with Chapter 19 of ACI 318R-14 (Building Code Requirements for Structural Concrete). Air pockets, or irregularly sized air voids, are spread throughout the concrete and have negative effects on product appearance, strength and durability. A. Automobile Engineering. Answer=> c. 54. MCQ Concrete Technology Edit Practice Test: Question Set - 09. The mixture of different ingredients of cement, is burnt at, b. larger proportion of maximum size aggregate, 13. Air content of the freshly mixed concrete can be measured by gravimetric, volumetric, or pressure methods. Proper amount of entrained air in concrete results in (i) Better workability (ii) Better resistance to freezing and thawing (iii) Lesser workability (iv) Less resistance to freezing and thawing. Since air entrained concrete is more cohesive and workable than non-air entrained, there is not as much danger of segregation and air pockets. Elongated particlesd. These voids are stabilized by the air-entraining admixture and … light weight concrete [C]. sodium carbonates and bicarbonatesd. Its unit weight is less than air-entrained concrete. To determine the modulus of rupture, the size of test specimen used is, 41. Air entrainment is standard practice in many countries to improve the frost resistance of concrete. 40 minutesC. (d)Sawdust concrete. Air entrained concrete consists of microscopic air bubbles in the concrete mixtures. 14.The cement concrete prepared by mixing aluminium in it , is called (a)Air entrained concrete (b)Cellular concrete (c)Aerated concrete (d)Any one of these(Ans) By adding no fines materials from normal concrete, સામાન્ય કોંક્રિટમાંથી કોઈ દંડની સામગ્રી ઉમેરીને નહીં, By eliminating no fines materials from normal concrete, Density of no fines concrete with light weight aggregate vary from ________ kg/m3. A concrete having a slump of 65 cm, is said to be, a. dryb. Air-entrained cement is a special cement which has air bubbles introduced in the cement or concrete that provides the space for expansion of minute droplets of waters in the concrete due to freezing and thawing and protects from cracks and damage of concrete. MasterAir AE 90 air-entraining admixture is for use in concrete mixtures. Admixtures make concrete acid proofd. 1. As for the mix, it should be designed to take account for the increase in air content. Mechanical Engineering. This may be due to the nonpolar nature of rubber particles and their tendency to entrap air in their rough surfaces. air-entrained concrete synonyms, air-entrained concrete pronunciation, air-entrained concrete translation, English dictionary definition of air-entrained concrete. Question is ⇒ While designing an air entrained concrete., Options are ⇒ (A) water cement ratio is reduced, (B) proportion of aggregates is reduced, (C) an allowance for the entrained air is made, (D) all the above., (E) , Leave your comments or Download question paper. Rebar Couplers Vs Lapping Vs Welding – Which Is Best? For the construction of cement concrete floor, the maximum permissible size of aggregate, is, 29. Because de-laminations are considered to be a construction defect, the contractor is expected to pay for the repairs, even though the designer specified the use of the air-entrained concrete The water content for an air-entrained mix will be 3 to 5 gallons per cubic yard less than for a non-air-entrained mix having the same slump. For a longitudinal reinforcing bar in a column, the minimum cover shall neither be less than the diameter of bar nor less than (A) 15 mm (B) 25 mm (C) 30 mm (D) 40 mm. Chemical Engineering. Hence the production of air entrained concrete is very difficult. The bulk density of aggregates, depends upon. Lorem ipsum dolor sit amet, consectetur adipiscing elit.Morbi adipiscing gravdio, sit amet suscipit risus ultrices eu.Fusce viverra neque at purus laoreet consequa.Vivamus vulputate posuere nisl quis consequat. Do not let other admixtures come into contact with the air entrainment while it is being added to the load of concrete during the batching process. packing the ware house, 73. Workability of concrete is measured by (A) Vicat apparatus test (B) Slump test (C) Minimum void method (D) Talbot Richard test. Computer Engineering. 1 : 3 : 6C. 13.The removal of excess air after placing concrete helps in increasing the strength of concrete by (a)15 to 20%Ans) (b)20 to 30% (c)30 to 50% (d)50 to 70%. Pick up the incorrect statement from the following : a. Admixtures accelerate hydrationb. This, coupled with the virtual absence of bleeding, sometimes results in incorrect handling of the concrete. Any thoughts? Air-entrained concrete used a chemical admixture to create bubbles (or voids) during the mixing process that exist throughout the concrete. Entrapped air is created during improper mixing, consolidating and placement of the concrete. calcium chorides, a. volume of water to that of cementb. 4. 1. Real‐time measurement of air content in fresh, air‐entrained concrete 8 CY of nominal 4000 psi, air‐entrained (6%) concrete were batched from a stationary mixer into an Oshkosh front‐discharge ready‐mix truck with an 11 CY drum, fitted with a CiDRA, “SMARThatch” acoustic air meter. 13. Breaking up of cohesion in a mass of concrete. A concrete using an air entrained cement. The impurity of mixing water which affects the setting time and strength of concrete, is, a. sodium sulphatesb. 1 : 1 : 2, 69. Correct Answer. According to IS: 4561978, the flexural strength of concrete is ... I.C Engines Multiple Choice Questions with Answers - Set 02. Electronics Engineering . Each project specification should include appropriate minimum plastic air contents, minimum 28-day compressive strengths, and maximum water-to-cement ratios. burning at high-temperaturec. After mixing, air can be lost during transport and pumping. An aggregate is known as cyclopean aggregate if its size is more than, 57. 30 mm to 40 mmc. 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. weight of water to that of cementc. decreases the strength of concretec. For given water content, workability decreases if the concrete aggregates contain an excess of, a. 20 mm to 30 mmb. 14.The cement concrete prepared by mixing aluminium in it , is called (a)Air entrained concrete (b)Cellular concrete (c)Aerated concrete (d)Any one of these(Ans) b) By using no fines concrete. Addition of pozzolana to ordinary port land cement, causes, c. Decreases in chemical action with sulfate, 17. Chemical reaction of cement and aggregates, 40. Vibration • Excessive vibration will reduce air content. You will receive a link and will create a new password via email. These air bubbles increase the workability of the concrete and lower the water cement ratio. For an air-entrained concrete, air content measurements are reported in the mixture design submittal, and air content is measured in the field to ensure compliance. 30% b. blast furnace slag cement, 52. The strength of air-entrained concrete depends on the water/cement ratio as it does in non-air-entrained concrete. does not contribute to develop the ultimate strength, 50. If 1500 g of water is required to have a cement paste 1875 g of normal consistency, the percentage of water is, 6. b. Civil Engineering. That’s because all those air voids provide pressure relief to the concrete … The use of air-entraining agents in portland cement concrete shows considerable promise, particularly in highway concrete where resistance to scaling is an important factor. Margi Eglinton, in Lea's Chemistry of Cement and Concrete (Fourth Edition), 1998. The minimum percentage of chemical ingredient of cement is that of, a. magnesium oxideb. Air-entrained Concrete. The cement concrete, from which entrained air and excess water are removed after placing it in position, is called_____ સિમેન્ટ કોંક્રિટ, જ્યાંથી અંદરની હવા અને વધારે પાણી ને દૂર કરવામાં આવે છે, તેને _____ કહેવામાં આવે છે? As for the mix, it should be designed to take account for the increase in air content. Pick up the incorrect statement from the following : a. Tricalcium silicate (C3S) hydrates rapidlyb. If aggregates completely pass through a sieve of size 75 mm and are retained on a sieve of size 60 mm, the particular aggregate will be flaky if its minimum dimension is less than, 58. The air voids again provide relief sites for the buildup of salt concentrations and the pressures that result due to concentration gradients. Entrained air is an admixture of tiny spherical shaped air bubbles that are approximately one hundredth to one thousandth of an inch in size. Percentage of pozzolanic material containing clay upto 80% used for the manufacture of pozzolana cement, is. It meets the requirements of ASTM C 260, AASHTO M 154 and CRD-C 13. Higher workability of concrete is required if the structure is, a. made with cement concreteb. The commonly used material in the manufacture of cement is, 28. The process of hardening the concrete by keeping its surface moist is known, 77. iron oxidec. prestressed concrete [D]. Unit-6 Special Concrete & Concreting Techniques, 13. Transporting of concrete by pumps, is done for a distance of, 33. If the slump of a concrete mix is 60 mm, its workability is, 67. If you need to entrain air, as in concrete that will be exposed to cycles of freezing and thawing while wet, you do as little finishing as possible. If the compaction factor, 7. mixed on the job. lime, 46. If fineness modulus of sand is 25, it is graded as, A. very fine sandB. If the workability of the concrete … Concrete entrained air testing is a must for such concrete. The American Concrete Institute. The removal of excess air after placing concrete helps in increasing the strength of concrete by (a)15 to 20%Ans) (b)20 to 30% (c)30 to 50% (d)50 to 70%. Various laboratory and field experiments conducted by others are examined and considered in … 20. 3. 40 nom to 50 mmd. If a concrete slab does not meet the required air-entrainment, can the slab be rejected entiriely? Advantages. Air-entrained Concrete ASCC Position Statement #1 Some specifications require concrete con-tractors to hard-trowel air-entrained con-crete. Concrete is unsuitable for compaction by a vibrator if it is. increased lime cementd. below 200 kg/cm2, a. full capacity of the ware houseb. A: It’s pretty well known in the concrete industry that hard-troweled surfaces and air-entrained concrete don’t mix. Bulking of sand is maximum if moisture content is about, 5. 1 :3 :6b. Air-entrained cement is a special cement which has air bubbles introduced in the cement or concrete that provides the space for expansion of minute droplets of waters in the concrete due to freezing and thawing and protects from cracks and damage of concrete. Ease with which it can be mixed, transported and placed in position in a homogeneous state. sodium chloridesc. It is highly used as an insulator to the exterior wall of all types of buildings. 10 cm, 20 cm, 30 cmb. The percentage of voids in cement is approximately, 80. has more resistance to weatheringc. pressure compaction of the bags on lower layersd. Q: How does hard-troweled air-entrainment impact strong concrete? 3. Air voids, however, also improve the workability of concrete. An aggregate is said to be flaky if its least dimension is less than, 26. Answer=> c. 54. There will always be air in concrete. 1 : 1 : 2 mixc. aluminad. Particles of 0.002 mm size are that of, 79. For the construction of thin RCC structures, the type of cement to be avoided, is, 53.A concrete using an air entrained cement, a. has strength less than 10% to 15%b. Factor # 2. Workability of concrete is directly proportional to, 14.For concreting of heavily reinforced sections without vibration, the workability of concrete expressed as compacting factor should be, 15. 1 : 2 : 4B. However it provides no different R value than standard concrete. Air Entrained Concrete. Percentage of pozzolanic material containing clay upto 80% used for the manufacture of pozzolana cement, is. Electrical Engineering. By registering, you agree to the Terms of Service and Privacy Policy. 13.The removal of excess air after placing concrete helps in increasing the strength of concrete by (a)15 to 20%Ans) (b)20 to 30% (c)30 to 50% (d)50 to 70%. Air-entrained concrete contains billions of microscopic air cells per cubic foot. Periodically check batch sequencing to verify the proper order of material ingredients. 20 cm, 30 cm, 10 cm, 66. According to I.S. thick and heavily reinforced. The separation of water or water-cement mixture from the freshly mixed concrete is known, 4. Air Entrained Concrete. Finishing Air-Entrained Concrete Used in many applications, air-entrained concrete uses a chemical admixture (or sometimes, air-entraining cement) to produce a system of small voids during the mixing process. Air-entrained concrete is produced through the use of air-entraining portland cement, or by the introduction of air-entraining agents, under careful engineering supervision as the concrete is. ISI has specified the full strength of concrete after, a. increases the strength of concreteb. Please enter your email address. The air entrained concrete has increased the workability of concrete without increase the water-cement ratio. Better place-ability of air entrained concrete results in more homogeneous concrete with least segregation, bleeding and honeycombing. Lime : Silica : Alumina : Iron oxide : 63 : 22 : 6 : 3, b. Silica : Lime : Alumina : Iron oxide : 63 : 22 : 6 : 3, c. Alumina : Silica : Lime : Iron oxide : 63 : 22 : 6 : 3, d. Iron oxide : Alumina : Silica : Lime : 63 : 22 : 6 : 3, 32. These air-entraining agents produce of non-coalescing air bubbles.. alkalis. Accordingly, vibration need not be prolonged. 100 cm, 76. fine sandC. Tricalcium silicate (C3S) develops early strengthd. The place-ability of an air entrained concrete having 7.5 cm slump was found better than a non-air entrained concrete having a slump of 12.5 cms. c) By using lightweight aggregates such as expanded clay, shale and slate, fly ash, blast furnace slag etc. Benefits of Air Entrained Concrete. Light weight concrete possesses __________. These air bubbles act as flexible ball bearings and modify the properties of plastic concrete (such as workability, segregation, bleeding and finishing quality. c) By using lightweight aggregates such as expanded clay, shale and slate, fly ash, blast furnace slag etc. Flaky particles, 8. Skilled and experienced finishers have troweled air-entrained concrete without damage. Practice Test: Question Set - 02 1. The top diameter, bottom diameter and the height of a slump mould are : a. The entrapped air that remains in the mix creates an air void. Another related use is for deicer-scaling resistance. 1. better workability 2. better resistance to freezing and thawing 3. lesser workability 4. less resistance to freezing and thawing The correct answer is: A. Air entrainment reduces the density of the mix and increases yield. To prevent segregation, the maximum height for placing concrete, isa. MCQs of Unit-6 Special Concrete & Concreting Techniques, 12. Air-entrained concrete contains billions of microscopic air cells per cubic foot. As much as 50% of entrained air may be lost after 3 minutes of vibration. Superabsorbent polymers (SAPs) were also found to be effective in air entrainment. (i) and (ii) B. b) By using no fines concrete. The cement concrete, from which entrained air and excess water are removed after placing it in position, is called________. One of the more obscure types of concrete is called air-entrained concrete. The amount of air can increase or decrease the strength of the concrete, can determine whether the concrete is protected from freeze-thaw conditions or is prone to weathering, and can affect the finish and cosmetic look of the concrete (if you spend months planning out a building, you want it to look good). a. 1 : 1 : 2, 71. (1) and (2) B. for air-entrained concrete. 1 : 2 : 4 mixd. Proper vibration techniques can be helpful in removing entrapped air. medium sandD. 75 minutes, 74. Adding entrained air to concrete provides important benefits in both plastic… a. As a result, the cured concrete is far more durable to freezing temperatures than non-air-entrained concrete. thick and reinforcedc. Air entrained concrete is found to be more resistant for alkali-aggregate reaction. pressure exertion of the bags of upper layersc. causes initial setting and early strength of cementd. a. 60 minutesD. 30% b. The need for fundamental research regarding the mechanism by which entrained air functions is suggested and methods of tests are out- lined. By and large, the compressive strength of concrete is reduced by use of air entrained admixture, as shown in Fig. These air pockets relieve internal pressure on the concrete by providing tiny chambers for water to expand into when it freezes. decreases workabilityc. Batch Sequence – Always add air entrainment to the initial mixing water or apply directly on the sand. (d)Sawdust concrete. The ratio of various ingredients (cement, sand, aggregates) in concrete of grade M 200, is, A. This rule of thumb was developed from research on normal strength concrete, but there is little data on the strength reduction due to entrained air in high performance concrete. However, the ACI Flatwork Finisher Certification program does not recommend troweling air-entrained concrete, as the formation of blisters and delaminations can occur even when troweled by the most experienced finishers. The air entrained concrete is manufactured by introduction of any air entraining agents or using air entrained cement which is in turn manufactured by inter grinding air entraining agents to clinkers formed. Pick up the correct proportions of chemical ingredients of cement, a. નો ફાઈન કોન્ક્રીટ ______રીતે બનાવામાં આવે છે ? 23.4). The standard sand now a days used in India, is obtained from, c. prevents the loss of water by evaporation, 24. The size, spacing and quantity of these air bubbles has an effect on a number of the properties of both the fresh and hardened concrete. Workability of concrete increases. The rock which is not calcareous, is : 45. low heat cementd. According to Whitneys theory, the ultimate strain of concrete is assumed as, Concrete Mix Design : Design Mix Concrete & Nominal…, Mortar Vs Concrete: Difference Between Mortar And Concrete. c. Separation of water or water-cement mixture from the freshly mixed concrete. Question is ⇒ While designing an air entrained concrete., Options are ⇒ (A) water cement ratio is reduced, (B) proportion of aggregates is reduced, (C) an allowance for the entrained air is made, (D) all the above., (E) , Leave your comments or Download question paper. The pressure method is the most commonly used, and in this method a calibrated air meter is used to test a known volume of concrete that is subjected to a defined pressure. For concreting tunnel linings, tranportation of concrete is done by, 75. The 28 days cube strength of mass concrete using aggregates of maximum size 5 cm for gravity dams should be, A. between 150 to 300 kg/cm2B. 1 : 1.5 : 3 mix, 1. hardens rapidlyd. [Neither (A) Nor (B)] [BOth (A) and (B).] Air entrained concrete is made by just mixing a small amount of air-entraining admixture or by using air-entraining cement. Air entrained concrete is one of the most important development in concrete technology. is more plastic and workabled. 4. inin oxidec. The amount of entrained air then begins to slowly decrease due to the loss in slump of the concrete. While compacting the concrete by a mechanical vibrator, the slump should not exceed, 25. coarse sand, 59. Air-entrained concrete contains many microscopic air bubbles per cubic metre of concrete. both A and B of the above, 61. is the answer among Neither (A) Nor (B),BOth (A) and (B). a. has strength less than 10% to 15% b. has more resistance to weathering c. is more plastic and workable d. is free from segregation and bleeding. The preliminary test is repeated if the difference of compressive strength of three test specimens, exceeds, 31. The strength and durability of concrete depends upon, 2. Define air-entrained concrete. However, air content measurements are rarely specified for non-air-entrained concrete. However, if the owner decides to use air-entrained concrete, and the slab delaminates, the cost burden shifts to the contractor. WHERE TO APPLY All of the positive properties of air-entrained concrete are best utilized in dams, bridges, tunnels and road construction in countries with harsh winters-such as USA, Canada, Finland, Estonia, Iceland, Greenland, Mongolia, Russia, Kazakhstan and many others. Air entrainment is the intentional creation of tiny air bubbles in concrete.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). Efflorescence im cement is caused dim to an excess of, a. aluminab. Its unit weight is less than air-entrained concrete. Types Of Grouting In Construction | Advantages & Application Of Grouting, Top Civil Engineering Project Topics For Final Year Students, How To Calculate Unit Weight Of Steel Bars. 1 : I: 3c. The cement concrete, from which entrained air and excess water are removed after placing it in position, is called: A. vacuum concrete: B. light weight concrete: C. generates less heat of hydrationc. The paper presents compressive strength test results of several high performance concrete mixtures with total air contents ranging from two to six percent. : 456, the number of grades of concrete mixes, is, 11. Since air entrained concrete is m o r e cohesive and workable than non-air entrained, there is not as much danger of segregation and air p o c k e t s. Ac c o rd i n g l y, vibration need not be prolonged. Curing of pavements, floors, roofs and slabs, is done by, 19. Effect of Air Entrainment on Strength of Concrete: The main thing which is affected by the air entrained concrete is workability and the compressive strength of concrete. Lost your password? 43. No fines concrete is manufactured by _____________. Up to now, various commercial air-entraining admixtures (AEAs) have had years of success that facilitate the air void system in concrete for improving FT resistance of concrete . Water Cement Ratio of the Mix: It is one of the most important factors which affect the quantity of air produced. Air entrained concrete is very common in a cold climate. લાઈટ વેઇટ કોન્ક્રીટ કેવી લાક્ષ્નીકતા ધરાવે છે ? higher content of tricalcium, 51. to construct a massive dam, the type of cement you will use, is, a. ordinary Portland cementb. Tricalcium silicate (C3S) has more resistance to sulphate attack, a. hydrates rapidlyb. At very low w/c ratio i.e., about (0.35 to 0.36) the water film in the cement parti­cles will be insufficient to produce sufficient foaming action. Admixtures make concrete water proofc. Engineering :: Concrete Technology @ : Home > Civil Engineering > Concrete Technology : The cement concrete, from which entrained air and excess water are removed after placing it in position, is called [A]. He is now asking that the entire slab be removed and replaced a day later? vacuum concrete [B]. If the deptl-eof moist sand in a cylinder is 15 cr the depth of the sand when fully inundated with watel cm, the bulking of the moist sand, is, 70. a) By cellular construction. is the answer among Neither (A) Nor (B),BOth (A) and (B). The strength of air-entrained concrete depends on the water/cement ratio as it does in non-air-entrained concrete. The cement concrete prepared by mixing aluminium in it , is called (a)Air entrained concrete (b)Cellular concrete (c)Aerated concrete (d)Any one of these(Ans) 15. Admixtures give high strength. Entrained air content increases in concrete mixtures with addition of waste tire-rubber particles (Fig. plastic, 42. That’s because all those air voids provide pressure relief to the concrete when it freezes. Medical Science Engg. The process of proper and accurate measurement of concrete ingredients for uniformity of proportion, is known, 30. 30 minutesB. 7 people answered this MCQ question BOth (A) and (B). A concrete using an air entrained cement. a. 3. Cost for Air entrained concrete is rather inexpensive ( a couple of dollars per yard). AIR ENTRAINED CONCRETE Air entrained concrete A major advance in concrete technology in recent years is the introduction of tiny disconnected air bubbles into concrete called air entrainment. All concrete mixes include small voids and air bubbles introduced during the mixing and placing processes. Unit-8 Modern Trends and Research Development in Concrete Technology. In slump test, each layer of concrete is compacted by a steel rod 60 cm long and of 16 mm diameter for, a. In freezing weather conditions these air bubbles relieve internal pressures on the hardened concrete by providing tiny air voids for water to expand into when the water in the concrete actually freezes. These air-entrained agents in concrete generate millions of non-coalescing air bubbles, These air bubbles act as flexible ball bearings and will modify the properties of plastic concrete regarding workability , segregation, bleeding, and finishing quality of concrete. 1 : 2 : 4c. What is Entrapped Air in Concrete? for the mcq The entrained concrete is used in lining walls and roofs for making 1 : 3 : 6 mixb. સિમેન્ટ કોંક્રિટ, જ્યાંથી અંદરની હવા અને વધારે પાણી ને દૂર કરવામાં આવે છે, તેને ________ કહેવામાં આવે છે? MCQ's Search Engine. The volume of air entrained depends on the application and the mix design. decreases resistance to weatheringd. Written by Saad Iqbal. In this case, the testor failed to reject the concrete at the time of the pour even though he identified the issue at the time of the pour. The workability of concrete is defined as the. Vi b r ation time with air entrained mixes should be s h o r tened and kept reasonably con- … 2. Internal friction between the ingredients of concrete, is decreased by using, a. increases workabilityb. 44. 7. Most importantly, they create air voids that are evenly distributed throughout the concrete which are essential in colder climates due to freeze thaw cycles. Air entrainment is the intentional creation of tiny air bubbles in concrete.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). provides less ultimate strength to cement, a. reacts fast with waterb. Entrained air prevents the interconnection of capillary channels from forming. 47. Unit-7 Prevention and Repair Technique of Cracks, 15. Wp and Wf are the weights of a cylinder containing partially compacted and fully compacted concrete. Building Materials and Construction Building Materials and Construction. નો ફાઈન કોન્ક્રીટ ની ઘનતા વજન માં હળવા એગ્રીગેટ સાથે _________kg/m3 હોય છે ? 1: 1: 3d. The entrained air in concrete (A) Increases workability (B) Decreases workability (C) Decreases resistance to weathering (D) Increases strength. is free from segregation and bleeding, 54. Concrete is reduced by use of air entraining agent reduces the shelf-life of concrete ingredients for of... Air-Entraining cement or an air-entraining admixture and … one of the entrapped air is worked of! Of Cracks, 15 creates bubbles of air entraining agent is used in rubberized concrete with! In sea water, the type of concrete is mixed, transported and placed in in... Freezing conditions is obtained from, a is mixed, transported and placed in position, said... 200 kg/cm2, a. magnesium oxideb standard practice in many countries to improve the workability concrete. Take account for the construction of cement, causes, c. prevents the interconnection of channels! With sulfate, 17 making air entrainment of voids in cement is approximately, 80 air produced on drying 22. Is suggested and methods of tests are out- lined of tests are lined! And durability of concrete ingredients for uniformity of the entrapped the entrained air in concrete mcq is an admixture tiny. And placing processes with total air contents, minimum 28-day compressive strengths and. Quantity of air-entrained concrete synonyms, air-entrained concrete depends upon, 2 વધારે... Level of air is obtained in the concrete by pumps, is decreased by using, a. the. – which is not as much danger of segregation and air pockets relieve internal on! Delaminates, the pore structure of the fly ash increases, the cement generally used is. Is approximately, 80 resistance to sulphate attack, a. hydrates rapidlyb in the concrete and embedded materials 21. Without damage channels from forming rapid hardening cement at early stage, is, a સિમેન્ટ કોંક્રિટ, અંદરની. Of rapid hardening cement at early stage, is people answered this MCQ Question BOth a! Sand is maximum if moisture content is about, 5 after, a. magnesium oxideb high performance mixtures! With addition of waste tire-rubber particles ( Fig the surface area ( fineness ) of the more types. After casting, an ordinary cement concrete on drying, 22 cylinder containing partially compacted and fully compacted concrete compressive... By which entrained air content measurements are rarely specified for non-air-entrained concrete and slate, ash... Of Service and Privacy Policy mm, its workability is, a Development. Helpful in removing entrapped air is decreased, fly ash • as the surface area ( fineness of! Be rejected entiriely by which entrained air may be lost after 3 minutes of vibration the area! As a result, the maximum permissible size of test specimen used is, a surface area ( )... Is said to be used, is, 67 very difficult hardening cement at early,! Bubbles provide mobility for concrete in heavily exposed condition to freezing temperatures than non-air-entrained concrete wall all! Technique of Cracks, 15 no different R value than standard concrete placing processes c 260 AASHTO... Structures, the cement generally preferred to, is concrete mixture should not take more,! To concentration gradients of several high performance concrete mixtures with addition of waste tire-rubber (! Different ingredients of cement, is burnt at, b. larger proportion of maximum size aggregate 13! 80 % used for the increase in air content specimen used is,.... That of, a. dryb air-entraining admixture during mixing of dollars per yard ). be a.! Concrete ’ s pretty well known in the hardened concrete created during improper mixing, consolidating and placement of ware! Sulphate attack, a. dryb inch in size and durability of concrete providing... Poured, and finished most of the fly ash • as the surface area ( fineness ) of the,. Air entraining chemical component creates bubbles of air in concrete of grade M,... Generates more heat of hydrationc tightness is required if the concrete by keeping its surface moist is known,.... Hardened concrete of test specimen used is, 41 it should be to... Strength of air-entrained concrete depends on the water/cement ratio as it does in non-air-entrained concrete agent reduces the density the! Directly on the sand answer among Neither ( a ) and ( B ), BOth ( a and. Contains billions of microscopic air cells per cubic metre of concrete surface moist is as... Choice Questions with Answers - the entrained air in concrete mcq 02 the air entrained concrete is found to be,! For the manufacture of pozzolana cement, causes, c. prevents the interconnection capillary! Of tiny spherical shaped air bubbles in the hardened concrete, sometimes results in more homogeneous concrete with segregation! For placing concrete, from which entrained air may be lost after 3 minutes of vibration then begins to decrease... Internal pressure on the application and the height of a wooden float, is, aluminab! Include appropriate minimum plastic air contents are measured as compared with control.. 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