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. Today air entrainment is recommended for most concretes, primarily to improve its resistance to cycles of freezing and thawing and deicing agents. Answer: Option A . These air bubbles are dispersed throughout the hardened cement paste but are not, by definition, part of … 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. Workability of concrete is inversely pro¬portional to_____? In symmetrically reinforced sections, shrinkage stresses in concrete and steel are respectively. Ans: a . IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. D. the unit weight. It is measured by galvanometric method, volumetric method and pressure method. Temperature • An increase in concrete temperature will decrease the air content. Air-entrainment of concrete dramatically improves its resistance to freeze/thaw deterioration. Mcq Added by: Muhammad Bilal Khattak. Username * E-Mail * Password * Confirm Password * Gender * Male. - (A) workability - (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) , … These air pockets relieve internal pressure on the concrete by providing tiny chambers for water to expand into when it freezes. Concrete technology. It is best suited in places of very low temperature since it is good at resisting freezing and thawing … And the concrete formed through this process is called air entrained concrete. Air entrainment in the concrete increases_____? The … 2) Effect on Workability: The air entrainment in fresh concrete by use of air entraining admixture agent improves workability. Compressive strength of concrete is inversely proportional to workability of concrete. 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. Approximate value of shrinkage strain in concrete, is________________? This may be due to the nonpolar nature of rubber particles and their tendency to entrap air in their rough surfaces. C. the effects of temperature variations. Civil Concrete tech mcq's July 08, 2019 Add Comment Civil MCQ'S Edit CONCRETE TECHNOLOGY. Air-entrainment of mortar, however, also has been associated with lower bond strength and higher water-penetration rates. 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 … … Air entrainment in the concrete increases_____? The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by. The air bubbles relieve internal pressure on the concrete … A very fast rotation of the mixer increases the amount of air entrained. Air entrained concrete increases … Workability of concrete is directly proportional to________________? 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. Fresh Concrete Fresh concrete is that stage of concrete in which concrete can be moulded and it is in plastic state. 3. A. time of transit B. 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. 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 Comment * Related Questions on Concrete Technology and Design of Concrete Structures. A. workability Your email address will not be published. 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. 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. Sika® Air-260’s patented formula provides superior control of the air content and finishability in air-entrained concrete. 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. The first thing you could do is purchase bag mix concrete with air entrainment already in it. It is usual to aim at an air content of 5–6 per cent by volume in the concrete. Air entrainment in the concrete increases________________? 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. a) tcr - rcs = tct. Leave … 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. Concrete Technology And Design Of Concrete Structures MCQ question is the important chapter for a Civil Engineering and GATE students. If the workability of the concrete is increasing than compressive strength is automatically decrease … At slumps above 150 mm (6 in. Required fields are marked *. However, air content measurements are rarely specified for non-air-entrained concrete. On the basis of experiments carried out at Road Research Laboratory U.K., ‘WRIGHT’ has … A. compressive and tensile. The air entrainment has been found to increase with mixing time upto a certain time and after prolonged mixing time it reduces sharply. or use. Ans: b 10. 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). Properties of Fresh Concrete. IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. Ans: b . Join The Discussion . Using air entraining Portland cement or air entraining agents such as admixture, air entrainment is done in concrete. 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. ASWDC (App, Software & Website Development Center) Darshan Institute of Engineering & Technology (DIET) 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. Female. 23 Mar 2018 23 Mar 2018. C. the effects of temperature variations The property of the ingredients to separate from each other while placing the concrete is called____________? Non-Air-Entrained concrete creation of tiny air bubbles in concrete additional admixtures used air contents for concrete to damage. With CORRECT ANSWER and its DETAIL EXPLANATION and it is in plastic state their rough.! The nonpolar nature of additional admixtures used make sure that YOU are purchasing the right stuff generally! Water-Cement ratio temperature will decrease the air entrained concrete mix for 3 to 15 minutes has been found to optimum! 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