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- What is the minimum grade of concrete, to be used, specified by IS: 456–2000? How surface
moisture of aggregates is accounted for in the mix design? - Discuss briefly the following with regards to mix design.
(a) Workability
(b) Strength
(c) Durability
Which one you consider to be of utmost importance? Give reasons. - What is the acceptance criteria of the concrete? Discuss briefly how the quality of concrete
is controlled. - Define following
(a) Target mean strength (b) Controlled concrete
(c) Compacting factor (d) Aggregate-cement ratio
(e) Water-cement ratio - Differentiate between
(a) Preliminary and trial mixes
(b) Medium and high strength concrete. - List the various methods of mix design. Briefly describe the IS code method.
- Design a mix for the following data
Characteristic compressive strength35 N/mm^2
Size of aggregate 20 mm, 10 mm
Shape of aggregate angular
Compacting factor 0.8
Degree of quality control good
Type of exposure mild
Sp. gr. of cement 3.15
Sp. gr. of coarse aggregate 2.70
Sp. gr. of fine aggregate 2.61
Water absorption in (per cent)
Coarse aggregate 0.6
Fine aggregate 1.0
Surface moisture (per cent)
Coarse aggregate nil
Fine aggregate 1
Cement 43 grade
Sand conforming to Zone III
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- To make one cubic meter of 1:2:4 by volume concrete, the volume of coarse aggregate
required is
(a) 0.94 m^3 (b) 0.85 m^3 (c) 0.75 m^3 (d) 0.65 m^3 - If in a concrete mix the fineness modulus of coarse aggregate is 7.6, the fineness modulus
of fine aggregate is 2.8 and the economical value of the fineness modulus of combined
aggregate is 6.4, then the proportion of fine aggregate is
(a) 25% (b) 33.33% (c) 50% (d) 66.67%