11.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 The correct answer is

12.Which of the following cements is suitable for use in massive concrete structures such as large dams ?

13.Minimum thickness of wall where single flemish bond can be used is

14.The ratio of the thickness of web to that of flange of steel rolled structural beams and channels is

15.The most commonly used retarder in cement is