148. Mix Design Performance of M 12.5 Grade Mass Concrete for 92 m High Wangkha Dam in Bhutan

This paper deals with the strength and cement requirement in mass concrete of M 12.5 grade being used for the construction of 92 m high concrete gravity Wangkha dam for 1020 MW Tala Hydroelectric Project in Bhutan. The cement content in the mass concrete has been optimised based on laboratory trials of various mix designs, field performance of mass concrete and the management of quality control at site. Portland Slag Cement (PSC) is being used for the construction of dam due to alkali reactive nature of aggregates. Based on the cubes/cores compressive strength of concrete and the degree of quality control exercised, long-term required strength has been achieved even after reducing the cement content by 60 kg/m³ from 210 kg/m³ to 150 kg/m³ in M 12.5 A150 grade of mass concrete. The cement content of more than 180 kg/m³ in M 12.5 grade mass concrete showed some decrease in strength.