Fly ash concrete-a step forward in sustainable construction of nuclear power plant S. B. Kulkarni, S. N. Bhat, A. Ragupathy, K. Kiran

The recent growth in the construction industry puts India at risk of increasing carbon emission and depletion of natural resources. Additional industrial by-products such as fly ash which is generated in thermal power plants increasing the greenhouse gas (GHG). The utilisation of such industrial byproducts supports the sustainable development of the construction industry and fly ash found to be the best partial replacement for ordinary portland cement (OPC). This paper presents a case study on the development and use of fly ash concrete at Kakrapar Atomic Power Plant-Unit 3 and 4 (KAPP 3 and 4). This manuscript enumerates the various aspects of testing and use of fly ash to produce fly ash concrete, which includes characterisation, source qualification, material testing methods, proportioning of concrete mix, direct blending and determination of hardened concrete properties at 40 and 50 % of cement replacement level. Benefits of fly ash concrete were experienced in both fresh and hardened states of concrete during the construction process, which include reduction in water requirement and fine aggregate content, improved workability, cohesiveness, pumping over long distance/heights, and concrete-ability at congested rebars and embedded parts. Though the rate of strength gain is low at early ages, there is considerable increase in strength at 56 days. The split tensile strength and modulus of elasticity follows the same trend as that of the compressive strength. Also, the rapid chlorideion penetration test (RCPT) values indicate the reduction in permeability of concrete leading to enhanced durability of fly ash concrete.