ABSTRACT
Mass work of Civil structures like dams require large quantity of concrete. Incorporation of pozzolana in concrete effect economy in cement consumption without affecting the properties of concrete. Considering the economy and fast speed of construction, worldwide development took place in utilising flyash in concrete with the advent of new construction material called as Roller Compacted Concrete (RCC). It is a concrete with no consistency (zero slump) with large replacement of cement by flyash, spread by dozers and compaction being carried out by vibratory rollers. Pozzolanic properties of flyash mainly attribute to the active Silica and Alumina content which readily react with free lime of cement to form additional compound of cementing property. Besides, its fineness helps in increasing plasticity and workability with reduced water-cement ratio, which results in increase in unit weight with higher strength development and water tightness.
For the first time in India, construction of two storage dams in RCC – namely Upper Dam and Lower Dam – under Ghatghar Pumped Storage Scheme are being undertaken by Irrigation Department, Government of Maharashtra, contemplating generation of 250 MW Hydro Power.
Mix designs were conducted considering 40% to 70% cement replacement by flyash and having 180, 200, 220, 240 kg/m3 cementitious contents. Final mix design evolved contains 60% cement replacement by flyash from Eklahare Thermal Power Plant, Nashik for 220 kg/m3 cementitious content (40% cement + 60% flyash) and for 0.523 water/cement ratio, gaining
150 kg/cm2 compressive strength at 91 days,
Density more than 2500 kg/m3,
Desired impermeability,
Modulus of Elasticity comparable to conventional concrete.
