This set of Prestressed Concrete Structures Multiple Choice Questions & Answers (MCQs) focuses on “High Strength Concrete”.
1. The developments in the field of concrete mix design, gave compressive strength ranging between:
Explanation: Recent developments in the field of concrete mix design have indicated that it is now possible to produce even ultra high strength concrete, of any desired 28 day cube compressive strength ranging from 70-100n/mm2 without taking resource to unusual materials.
2. High strength concrete resists:
c) Tangent moments
d) Trapezoidal moments
Explanation: The concrete in a prestressed concrete member is subjected to high bearing stresses due to anchoring at its ends and hence, high strength concrete is required to safely resist the bursting stresses at the end of the beam.
3. In high strength concrete, high modulus of elasticity in the beam is due to:
a) Elastic and creep strains
b) Principle tensile stresses
c) Reinforced beams
Explanation: Low shrinkage, minimum creep characteristics and a high value of young’s modulus are generally deemed necessary for concrete used for prestressed members and the loss of prestress in steel reinforcement is minimum because the elastic and creep strain are very small due to high modulus of elasticity.
4. Which of the following is one of the standard codes used for designing high strength concrete mixes?
a) BS 8110-1985
b) BS 883-1974
c) BS 8113-1986
d) BS 886-1976
Explanation: The various methods adopted for designing high strength concrete mixes are Erntroy and Shack lock’s empirical method, American concrete institute method, British DOE method, Indian standard code and British code BS 8110-1985 stipulates that not more than 5 percent of the test results should fall below 28 days characteristic strength.
5. Which of the following is the Indian code used for high strength concrete mixes?
a) IS 1343-1980
b) IS 10263-1982
c) IS 384-1980
d) IS 457-1979
Explanation: Indian standard code IS 1343-1980 and IS 456-1978 stipulates that only controlled concrete should be used for prestressed concrete construction and the exact specifications with regard to the acceptance criteria for concrete generally vary from one code to another.
6. The cube strength of concrete required for both pre tensioning and post tensioning according to Indian standard codes are:
a) 30 and 20
b) 15 and 25
c) 40 and 30
d) 45 and 35
Explanation: The minimum 28 day cube compressive strength prescribed in the Indian standard code IS 1343-1980 is 45n/mm2 for pretensioned members and 35n/mm2 for post tensioned members with the development of vibration techniques in 1930, it became possible to produce without much difficult, high strength concrete having 28 day compression strength in the range of 30-70n/mm2.
7. The full form of ACI method for mix design proportion is:
a) American committee institute
b) American council institute
c) American concrete institute
d) American cement institute
Explanation: American concrete institute’s mix design procedure for no slump is one of the methods used for high strength concrete mix design and the American concrete institute in a non profit technical society and standards developing organization, ACI was founded in January 1905.
8. In which method, high strength concrete mixes are designed by relating compressive strength to reference number?
a) Erntroy and Shack locks
b) American concrete institute method
c) British DOE method
d) Indian standard code method
Explanation: In Erntroy and Shack lock’s empirical method high strength concrete mixes are designed by using empirical graphs relating the compressive strength to reference number for concrete made with crushed Granite, coarse aggregates and irregular gravel and the range of the degrees of workability varying from externally low to high corresponds to the compacting factor values of 0.65 and 0.95.
9. The water cement ratio used for British DOE method is:
Explanation: In British DOE method based on the type of cement and coarse aggregate provided evaluate the compressive strength of concrete mix made with water cement ratio of 0.5 and the durability requirements of mix design. Doe is design of experiments is a methodology that can be effective for general problem solving as well as for improving or optimizing product design and manufacturing and production process.
10. The degree of workability of Indian standard method is:
Explanation: The degree of workability relating to compaction factor value is 0.80 for Indian standard method design for high strength concrete mix, the steps involved in Indian standard method is target mean strength, water cement ratio, maximum size of aggregates, degree of workability, considering all the factors the cement content is obtained.
Sanfoundry Global Education & Learning Series – Prestressed Concrete Structures.
To practice all areas of Prestressed Concrete Structures, here is complete set of 1000+ Multiple Choice Questions and Answers.