Compressive strength of concrete is inversely proportional to workability of concrete. More Related Questions on Design of Concrete Structures Mcqs. But make sure that you are purchasing the right stuff, generally it will be a Crack Resistant Mix that has air entrainment. I Recommend QUIKRETE® Crack Resistant Concrete Mix . 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. The amount of air in such concrete is usually between four to seven percent of the volume of concrete. ‘vater-cement ratio C. the air in the mix D. size of aggregate . Air entrainment is the process where many small air bubbles are distibuted into concrete and become part of the matrix that binds the aggregate together in the hardened concrete. www.gtu-mcq.com is an online portal for the preparation of the MCQ test of Degree and Diploma Engineering Students of the Gujarat Technological University Exam. Air entrainment in the concrete increases________________? 2) Effect on Workability: The air entrainment in fresh concrete by use of air entraining admixture agent improves workability. The fine air bubbles entrained in the concrete are very difficult to fill with water, thus reducing the degree of saturation, and their intimate distribution ensures that the distance between neighbouring air spaces is so small that pressures created by the growth of ice crystals are reduced. Air entrainment in the concrete increases________________? 1. The amount of air entrainment increases with mixing time but prolonging the mixing time too long will result in escape of the entrained air. A. compressive and tensile. Share the link on social media. On the basis of experiments carried out at Road Research Laboratory U.K., ‘WRIGHT’ has … 9. Comment * Related Questions on Concrete Technology and Design of Concrete Structures. ASWDC (App, Software & Website Development Center) Darshan Institute of Engineering & Technology (DIET) Air entrainment in the concrete increases? 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 is … - (A) workability - (B) strength The air entrainment has been found to increase with mixing time upto a certain time and after prolonged mixing time it reduces sharply. Road research Laboratory U.K, it is found that 5% air entrainment increases the compacting factor by 0.07, which would be equal to an increase in slump from 1.2 cm to 5.0 cms. The … Share. A very fast rotation of the mixer increases the amount of air entrained. Generally, an increase in the total air content of one percent decreases the compressive strength of concrete two to five percent. Air-entrainment of concrete dramatically improves its resistance to freeze/thaw deterioration. D. the unit weight. Therefore, those in the concrete industry have long been on the hunt for ways of increasing workability without sacrificing the strength of the finished product. or use. Ans: a . 0. Learn Concrete Technology And Design Of Concrete Structures MCQ questions & answers are available for a Civil Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Ans: b . Air entrainment is standard practice in many countries to improve the frost resistance of concrete. C) fcr d) fc5>fcr>fC. Air entrained concrete increases … - Spread the word. Although no air entraining agent is used in RC mixtures, higher air contents are measured as compared to control mixtures. Username or email * Password * Remember … Entrained air content increases in concrete mixtures with addition of waste tire rubber particles. These air pockets relieve internal pressure on the concrete by providing tiny chambers for water to expand into when it freezes. If the workability of the concrete is increasing than compressive strength is automatically decrease … Hpwever, entrained air is a trade-off with strength, as each one percent of air may result in five percent decrease in the compressivs strength. A. workability These air bubbles are dispersed throughout the hardened cement paste but are not, by definition, part of … A. workability B. strength C. the effects of temperature variations D. the unit weight. b) strength. Question is ⇒ Air entrainment in the concrete increases., Options are ⇒ (A) workability, (B) strength, (C) the effects of temperature variations, (D) the unit weight, (E) , … Your email address will not be published. Sign In Continue with Facebook. Concrete Technology And Design Of Concrete Structures MCQ question is the important chapter for a Civil Engineering and GATE students. Explanation are given for understanding. Air entrainment affects compressive strength of concrete and its workability. It is best suited in places of very low temperature since it is good at resisting freezing and thawing … Another term used… Follow Blog via Email. Join The Discussion . 23 Mar 2018 23 Mar 2018. Approximate value of shrinkage strain in concrete, is________________? … Design of Concrete Structures Design of Concrete Structures. It increases the workability of concrete without much increase in water-cement ratio. D. the unit weight. Answer: Option A . Required fields are marked *. In symmetrically reinforced sections, shrinkage stresses in concrete and steel are respectively. The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by_______________? At slumps above 150 mm (6 in. It is measured by galvanometric method, volumetric method and pressure method. Air-entrained concrete contains billions of microscopic air cells per cubic foot. The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by. Effect on Strength of Concrete: Generally it can be said that air entrainment in concrete reduces the compressive strength of concrete. C) fcr d) fc5>fcr>fC. A. workability B. strength C. the effects of temperature variations D. the unit weight. 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. Related Questions on Design of Concrete Structures Mcqs. And the concrete formed through this process is called air entrained concrete. The air entrained concrete has increased the workability of concrete without increase the water-cement ratio. Properties of Fresh Concrete. To determine the modulus of rupture, the size of test specimen used is a) 150 x150 x500 mm b) 100 x100 x700 mm c) 150 x150 x700 mm d) 100 x100 x500 mm 2. Strength of concrete increases with________________? This may be due to the nonpolar nature of rubber particles and their tendency to entrap air in their rough surfaces. Sign In Now. A. workability. Concrete technology; MCQ’S; Contact; About; Search for: Tag: air entrainment in concrete increases. Username * E-Mail * Password * Confirm Password * Gender * Male. (adsbygoogle = window.adsbygoogle || []).push({}); PakMcqs.com is the Pakistani Top Mcqs website, where you can find Mcqs of all Subjects, You can also Submit Mcqs of your recent test and Take online Mcqs Quiz test. Continue with Google. The air bubbles relieve internal pressure on the concrete … Air entrainment is the intentional creation of tiny air bubbles in concrete. Have an account? Facebook; Sign Up Continue with Facebook. B. strength Concrete Technology and Design MCQ with detailed explanation for interview, entrance and competitive exams. It also depends on the aggregate gradation and nature of additional admixtures used. Although the degree of these problems is in question, most studies show that at least some reduction in bond strength and increase in water penetration will occur. ), air contentsmay decrease. c) the effects of temperature variations. Some research suggests that chloride penetration is slowed by air entrainment up to 6%; some research suggests increased air content is neutral on Cl- penetration. Air entrainment will reduce damage during freeze- thaw cycles thereby increasing the concrete’s durability. The air bubbles are created during mixing of the plastic (easy flowing) concrete, and most of them survive to be part of the hardened concrete. Unfortunately, as concrete's water level increases, its strength rapidly drops off. Continue with Google. PLEASE COMMENT BELOW WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION. C. the effects of temperature variations. The process known as air entrainment allows contractors to achieve just this elusive goal. Increases in temperature from 21°C (70°F) to 38°C (100°F) may reduce air content by 25% while reductions from 21°C (70°F) to 5°C (40°F) may increase air content by as much as 40%. PLEASE COMMENT BELOW WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION. a) workability. Today air entrainment is recommended for most concretes, primarily to improve its resistance to cycles of freezing and thawing and deicing agents. Your email address will not be published. This increases the resistance of the concrete to freeze-thaw damage in cold climates.… Sika® Air-260’s patented formula provides superior control of the air content and finishability in air-entrained concrete. Workability of concrete is directly proportional to________________? The air entrained concrete due its increased advantages has various applications. Concrete technology. 3. or use. IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. This is also called "Green Concrete". A. time of transit B. 0. The property of the ingredients to separate from each other while placing the concrete is called____________? Air entrainment in the concrete increases. This type of air entrained concrete mix can usually be found on Amazon or at most local hardware stores. The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by a) tcr - rcs = tct b) fcr>fcs>fc. Air entrainment in the concrete increases a) workability b) strength c) the effects of temperature variations d) the unit weight Ans: a 9. 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). It has been noticed that air entrainment in concrete increases the resistance by about three to seven times in such a situation. C. the effects of temperature variations In addition to improving durability, air entraining in general reduces bleeding, improves workability, decreases water demand, improves sulfate resistance and slightly increases watertightness. Air entrainment in the concrete increases_____? Mixing the concrete mix for 3 to 15 minutes has been found to produce optimum air content. Mcq Added by: Muhammad Bilal Khattak. Female. Fresh Concrete Fresh concrete is that stage of concrete in which concrete can be moulded and it is in plastic state. DBMS MCQ Alphabetical Series MCQ Classification MCQ Chemistry in Service of Man MCQ Phylum - Mammalia MCQ Indian Polity & Economy MCQ Viruses MCQ Urinary Calculus Disease MCQ H.C.F and L.C.M MCQ Phylum - Porifera MCQ Boats and Streams MCQ Machine Input Mi-set 2 MCQ The effect of air entrainment on the compressive strength of high performance concrete is presented in this paper. It is usual to aim at an air content of 5–6 per cent by volume in the concrete. Air-entrainment of mortar, however, also has been associated with lower bond strength and higher water-penetration rates. Using air entraining Portland cement or air entraining agents such as admixture, air entrainment is done in concrete. However, air content measurements are rarely specified for non-air-entrained concrete. Air entrainment in the concrete increases. IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. You are in the ACI 318 C2 severe chloride exposure zone; Table 4.3.1 requires the concrete to have w/cm of 0.40 or less, and 5000 psi minimum strength. b) fcr>fcs>fc. Air entrainment in the concrete increases_____? MCQs: Air entrainment in the concrete increases? 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. d) the unit weight. The first thing you could do is purchase bag mix concrete with air entrainment already in it. Ans: b 10. 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. 10. Leave … B. strength. air contents for concrete to resist damage from cycles of freezing and thawing. Civil Concrete tech mcq's July 08, 2019 Add Comment Civil MCQ'S Edit CONCRETE TECHNOLOGY. Sika® Air-260 is a unique, synthetically manufactured surfactant for the air entrainment of concrete. Workability of concrete is inversely pro¬portional to_____? Temperature • An increase in concrete temperature will decrease the air content. a) tcr - rcs = tct. Air-260 ’ s patented formula provides superior control of the air in such concrete is called____________ proportional workability... Are rarely specified for non-air-entrained concrete mix that has air entrainment is done in concrete mixtures addition... 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