a) 0.50
b) 0.45
c) 0.60
d) 0.55
As per Cl. 8.2.2, Table 2 of IS 456:2000, the maximum free water-cement ratio is specified based on the exposure condition and concrete grade. For an ordinary reinforced concrete of M20 grade under mild exposure condition, this ratio should not exceed 0.55.
Therefore, option d) 0.55 is the correct maximum free water to cement ratio allowed for M20 grade reinforced concrete under mild exposure as per IS 456-2000 specifications.
