Concrete technology; MCQ’S; Contact; About; Search for: Tag: air entrainment in concrete increases. Ans: a . 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. This type of air entrained concrete mix can usually be found on Amazon or at most local hardware stores. 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) , … 23 Mar 2018 23 Mar 2018. Today air entrainment is recommended for most concretes, primarily to improve its resistance to cycles of freezing and thawing and deicing agents. Air entrainment in the concrete increases_____? But make sure that you are purchasing the right stuff, generally it will be a Crack Resistant Mix that has air entrainment. Facebook; Sign Up Continue with Facebook. or use. c) the effects of temperature variations. Air entrainment is the intentional creation of tiny air bubbles in concrete. The … At slumps above 150 mm (6 in. In addition to improving durability, air entraining in general reduces bleeding, improves workability, decreases water demand, improves sulfate resistance and slightly increases watertightness. Air-entrained concrete contains billions of microscopic air cells per cubic foot. (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. Comment * Related Questions on Concrete Technology and Design of Concrete Structures. And the concrete formed through this process is called air entrained concrete. Sign In Now. 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. If the workability of the concrete is increasing than compressive strength is automatically decrease … This may be due to the nonpolar nature of rubber particles and their tendency to entrap air in their rough surfaces. I Recommend QUIKRETE® Crack Resistant Concrete Mix . Sika® Air-260 is a unique, synthetically manufactured surfactant for the air entrainment of concrete. b) fcr>fcs>fc. 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. C) fcr d) fc5>fcr>fC. It is measured by galvanometric method, volumetric method and pressure method. Your email address will not be published. 10. a) workability. 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. 2) Effect on Workability: The air entrainment in fresh concrete by use of air entraining admixture agent improves workability. Air entrainment affects compressive strength of concrete and its workability. It increases the workability of concrete without much increase in water-cement ratio. … The air entrained concrete has increased the workability of concrete without increase the water-cement ratio. Compressive strength of concrete is inversely proportional to workability of concrete. Strength of concrete increases with________________? Fresh Concrete Fresh concrete is that stage of concrete in which concrete can be moulded and it is in plastic state. 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%. 9. 0. Concrete Technology And Design Of Concrete Structures MCQ question is the important chapter for a Civil Engineering and GATE students. A. workability. The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by_______________? - Spread the word. C) fcr d) fc5>fcr>fC. These air pockets relieve internal pressure on the concrete by providing tiny chambers for water to expand into when it freezes. This increases the resistance of the concrete to freeze-thaw damage in cold climates.… Explanation are given for understanding. However, air content measurements are rarely specified for non-air-entrained concrete. 0. The property of the ingredients to separate from each other while placing the concrete is called____________? The amount of air in such concrete is usually between four to seven percent of the volume of concrete. Civil Concrete tech mcq's July 08, 2019 Add Comment Civil MCQ'S Edit CONCRETE TECHNOLOGY. The process known as air entrainment allows contractors to achieve just this elusive goal. Air entrainment in the concrete increases? 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. Air entrainment in the concrete increases________________? Design of Concrete Structures Design of Concrete Structures. 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. A. compressive and tensile. A. workability Join The Discussion . B. strength. 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). Continue with Google. More Related Questions on Design of Concrete Structures Mcqs. A. workability B. strength C. the effects of temperature variations D. the unit weight. IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. 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. The effect of air entrainment on the compressive strength of high performance concrete is presented in this paper. It has been noticed that air entrainment in concrete increases the resistance by about three to seven times in such a situation. A. time of transit B. The air entrainment has been found to increase with mixing time upto a certain time and after prolonged mixing time it reduces sharply. 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. Approximate value of shrinkage strain in concrete, is________________? Effect on Strength of Concrete: Generally it can be said that air entrainment in concrete reduces the compressive strength of concrete. Required fields are marked *. C. the effects of temperature variations - (A) workability - (B) strength Ans: b 10. Air-entrainment of concrete dramatically improves its resistance to freeze/thaw deterioration. 1. Leave … Your email address will not be published. Another term used… Follow Blog via Email. It also depends on the aggregate gradation and nature of additional admixtures used. 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. IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. These air bubbles are dispersed throughout the hardened cement paste but are not, by definition, part of … PLEASE COMMENT BELOW WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION. Unfortunately, as concrete's water level increases, its strength rapidly drops off. A. workability B. strength C. the effects of temperature variations D. the unit weight. Workability of concrete is inversely pro¬portional to_____? ‘vater-cement ratio C. the air in the mix D. size of aggregate . ), air contentsmay decrease. 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. Air-entrainment of mortar, however, also has been associated with lower bond strength and higher water-penetration rates. PLEASE COMMENT BELOW WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION. D. the unit weight. Air entrainment in the concrete increases. 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. Share. Temperature • An increase in concrete temperature will decrease the air content. Air entrainment in the concrete increases________________? In symmetrically reinforced sections, shrinkage stresses in concrete and steel are respectively. Female. Air entrainment is standard practice in many countries to improve the frost resistance of concrete. Concrete Technology and Design MCQ with detailed explanation for interview, entrance and competitive exams. 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 a) tcr - rcs = tct. Continue with Google. b) strength. It is usual to aim at an air content of 5–6 per cent by volume in the concrete. Related Questions on Design of Concrete Structures Mcqs. The air entrained concrete due its increased advantages has various applications. 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. Username or email * Password * Remember … B. strength 3. Although no air entraining agent is used in RC mixtures, higher air contents are measured as compared to control mixtures. Concrete technology. Air entrained concrete increases … 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. C. the effects of temperature variations. This is also called "Green Concrete". The air bubbles relieve internal pressure on the concrete … Related Questions on Design of concrete without much increase in concrete and its DETAIL.. Water-Cement ratio increased advantages has various applications is measured by galvanometric method, volumetric method and pressure method Edit Technology... Resistant mix that has air entrainment is standard practice in many countries to improve its to... Is the intentional creation of tiny air bubbles in concrete entraining Portland cement or air entraining agent is used RC. Is inversely proportional to workability of concrete without much increase in concrete, is________________ and of... 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