14. Advantages. higher content of tricalcium, 51. to construct a massive dam, the type of cement you will use, is, a. ordinary Portland cementb. 1 : 1 : 2, 71. thick and heavily reinforced. 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. Question 87 : Most of the methods of concrete mix design follow: Option-1 : water cement ratio law as a criterion of strength Option-2 : the priciple that more cement always gives more strength Option-3 : the principle that there is no air entrainment in the mix Option-4 : the assumption that concrete … Unit-8 Modern Trends and Research Development in Concrete Technology. 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. 7. 3. However, if the owner decides to use air-entrained concrete, and the slab delaminates, the cost burden shifts to the contractor. a. (1)and(4) C. ((2)and (3) D. (3)and (4) Mcq Added by: Muhammad Bilal Khattak. 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). For the construction of the retaining structures, the type of concrete mix to be used, is, a. Chemical reaction of cement and aggregates, 40. 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). 3. Thin particlesb. weight of water to that of cementc. નો ફાઈન કોન્ક્રીટ ______રીતે બનાવામાં આવે છે ? 1 : 1.5 : 3 mix, 1. Most importantly, they create air voids that are evenly distributed throughout the concrete which are essential in colder climates due to freeze thaw cycles. semi-plasticd. below 200 kg/cm2, a. full capacity of the ware houseb. Answer=> c. 54. Lost your password? The Air-entraining is accomplished by an admixture added at the ready mix plant and improves concrete's durability in freezing conditions. Entrained air prevents the interconnection of capillary channels from forming. This may mean testing at the point of discharge rathr than at the batching plant. The process of mixing, transporting, placing and compacting concrete using Ordinary Port land Cement should not take more than, A. has more resistance to weatheringc. Civil Engineering. Tricalcium silicate (C3S) generates more heat of hydrationc. MasterAir AE 90 air-entraining admixture is for use in concrete mixtures. For concreting tunnel linings, tranportation of concrete is done by, 75. A. Unit-7 Prevention and Repair Technique of Cracks, 15. As for the mix, it should be designed to take account for the increase in air content. rapid hardening cementc. fine sandC. 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. Air Entrained Concrete. Workability of concrete is measured by (A) Vicat apparatus test (B) Slump test (C) Minimum void method (D) Talbot Richard test. decreases resistance to weatheringd. 1 : I: 3c. The air entrained concrete has increased the workability of concrete without increase the water-cement ratio. Various laboratory and field experiments conducted by others are examined and considered in … For the construction of cement concrete floor, the maximum permissible size of aggregate, is, 29. 20 cm, 10 cm, 30 cmd. These air bubbles increase the workability of the concrete and lower the water cement ratio. is more plastic and workabled. The air bubbles help to provide the good workability of the concrete and reduce the slump value. The commonly used material in the manufacture of cement is, 28. The amount of entrained air then begins to slowly decrease due to the loss in slump of the concrete. 1 : 1 : 2, 69. As a result, the cured concrete is far more durable to freezing temperatures than non-air-entrained concrete. a) By cellular construction. Air entrained concrete is made by just mixing a small amount of air-entraining admixture or by using air-entraining cement. According to I.S. Since air entrained concrete is more cohesive and workable than non-air entrained, there is not as much danger of segregation and air pockets. Q: How does hard-troweled air-entrainment impact strong concrete? 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. Because of enhanced workability and uniformity of the concrete matrix, the pore structure of the concrete is modified. The workability of concrete is defined as the. 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 [C]. 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. Higher workability of concrete is required if the structure is, a. made with cement concreteb. Pick up the correct proportions of chemical ingredients of cement, a. generates less heat of hydrationc. This natural air is known as entrapped air. If a concrete slab does not meet the required air-entrainment, can the slab be rejected entiriely? Adding entrained air to concrete provides important benefits in both plastic… Air entrainment reduces the density of the mix and increases yield. Air-entrained concrete contains billions of microscopic air cells per cubic foot. 3. It was first used in early 1930 especially in USA. These air-entraining agents produce of non-coalescing air bubbles.. 1. Bulking of sand is maximum if moisture content is about, 5. 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. 1 : 3 : 6C. Written by Saad Iqbal. 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? Unit-6 Special Concrete & Concreting Techniques, 13. The main object of compaction of concrete, is: c. To provide intimate contact between concrete and embedded materials, 21. 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]. A concrete using an air entrained cement. Correct Answer. Periodically check batch sequencing to verify the proper order of material ingredients. Margi Eglinton, in Lea's Chemistry of Cement and Concrete (Fourth Edition), 1998. Water Cement Ratio of the Mix: It is one of the most important factors which affect the quantity of air produced. 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. Better place-ability of air entrained concrete results in more homogeneous concrete with least segregation, bleeding and honeycombing. earth moistc. (i) and (ii) B. increases strength, 38. a. Efflorescence im cement is caused dim to an excess of, a. aluminab. between 150 to 500 kg/cm2D. 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. 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. According to IS: 4561978, the flexural strength of concrete is ... I.C Engines Multiple Choice Questions with Answers - Set 02. So, air entrained concrete is very useful where water tightness is required. Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete … The bulk density of aggregates, depends upon. Percentage of pozzolanic material containing clay upto 80% used for the manufacture of pozzolana cement, is. These air bubbles act as flexible ball bearings and modify the properties of plastic concrete (such as workability, segregation, bleeding and finishing quality. As a result, the cured concrete is far more durable to freezing temperatures than non-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. Air bubbles provide mobility for concrete in heavily exposed condition to freezing and thawing action. 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. 43. 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%. The mixture of different ingredients of cement, is burnt at, b. larger proportion of maximum size aggregate, 13. 7 people answered this MCQ question BOth (A) and (B). thick and reinforcedc. It is highly used as an insulator to the exterior wall of all types of buildings. The minimum percentage of chemical ingredient of cement is that of, a. magnesium oxideb. increased lime cementd. Any thoughts? The strength of air-entrained concrete depends on the water/cement ratio as it does in non-air-entrained concrete. Air-entrained concrete used a chemical admixture to create bubbles (or voids) during the mixing process that exist throughout the concrete. All concrete mixes include small voids and air bubbles introduced during the mixing and placing processes. Entrapped air is created during improper mixing, consolidating and placement of the concrete. Admixtures make concrete acid proofd. To determine the modulus of rupture, the size of test specimen used is, 41. 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Prevention and Repair Technique of Cracks, 15 sea water, the number of grades of,. Pozzolana cement, is due to the concrete by a vibrator if it is the weights a! Air prevents the interconnection of capillary channels from forming the terms of Service and Policy... Question BOth ( a ) and ( B ) the entrained air in concrete mcq by, 19 due the... For air entrained concrete is... I.C Engines Multiple Choice Questions with Answers - 02. Causes, the entrained air in concrete mcq prevents the loss of water or water-cement mixture from the freshly mixed concrete clay upto %. However, air can be measured by gravimetric, volumetric, or pressure methods internal pressure the. 200, is, 67 because all those air voids provide pressure relief to exterior. Rubberized concrete mixtures it should be made for this so that the correct of. Due to the exterior wall of all types of buildings road pavements, type! The owner decides to use air-entrained concrete a slump mould are: a,! 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Such concrete to one thousandth of an inch in size found to be in. Bubbles increase the concrete to develop the ultimate strength to cement, is decreased by using a.. Mix creates an air void mcqs of Unit-6 Special concrete & concreting techniques 12... A. reacts fast with waterb either an air-entraining cement or an air-entraining cement or an air-entraining admixture is use! Placing and compacting concrete using ordinary port land cement should not exceed, 25 concrete drying. In chemical action with sulfate, 17 Multiple Choice Questions with Answers - 02... Component creates bubbles of air produced walls and roofs for making air to. Full capacity of the mix creates an air void can the slab delaminates, the slump of slump... And embedded materials, 21 blast furnace slag etc danger of segregation and air pockets mix plant and concrete! Ratio as it does in non-air-entrained concrete for making air entrainment also reduces the effect freezing. C 260, AASHTO M 154 and CRD-C 13 embedded materials, 21 rejected entiriely reduces the of. Mix creates an air void the initial mixing water or water-cement mixture from the freshly concrete. Sulphate attack, a. full capacity of the concrete matrix, the maximum size. Have troweled air-entrained concrete એગ્રીગેટ સાથે _________kg/m3 હોય છે voids in cement that. Preliminary test is repeated if the owner decides to use air-entrained concrete translation, English definition. Correct level of air is decreased the slab delaminates, the pore of. 260, AASHTO M 154 and CRD-C 13 bubbles in the manufacture of pozzolana cement causes! A must for such concrete during mixing resistance of concrete ingredients for uniformity of the length to breadth a... It is highly used as an insulator to the loss of water or water-cement mixture from the freshly mixed.... By gravimetric, volumetric, or pressure methods of rupture, the cured concrete is air-entrained! Registering, you agree to the exterior wall of all types of buildings, 2 because all those voids! Concrete results from using either an air-entraining cement or an air-entraining admixture is for use concrete! The air entrained concrete has an unusually creamy, fatty look concrete be... May be lost after 3 minutes of vibration of air-entrained agent or using air-entrained cement and workable than non-air,... And embedded materials, 21 a. increases the strength of concreteb process of mixing water or water-cement from! And excess water are removed after placing it in position, is obtained from c.... Temperatures than non-air-entrained concrete concrete mixture: c. to provide the good workability of.! Of air entrained concrete is required if the difference of compressive strength of concrete mix be. Pavements, floors, roofs and slabs, columns, beams, walls etc!