Durability studies on ready mix concrete using mineral admixtures and manufactured sand

To meet the intensifying demand of fine aggregate in construction sector, manufactured sand has become a viable alternative to the river sand. Ready mix concrete (RMC) is playing vital role in fast-track construction particularly in Tire-II cities in India. The strength and durability concerns about using 100% manufactured sand along with mineral admixtures in RMC plant needs to be addressed through suitable experimental demonstrations. This research gives the experimental results on strength and durability studies of concrete carried out on samples obtained from RMC Plant by making use of manufactured sand containing (50% of crushed sand and 50% of the crushed rock fines) as replacement for natural sand. Trials on partial replacing cement with fly ash content of 33% and GGBS of 40% has also been carried out. Compressive and split-tensile strength studies were conducted on cubes (150mmx150mmx150mm) and cylinders (150mmx300mm) at 7, 14 & 28 days of curing. Non-Destructive tests such as Ultra Sonic Pulse Velocity (UPV) and rebound hammer tests were conducted to assess the quality of these mixes. Durability tests were conducted and comparison of the % of loss in mass and % of loss in strength for concrete samples subjected to acid attack, sulphate attack, alkaline attack tests were also carried out. Rapid chloride permeability test (RCPT) was conducted to check the concrete resistance against chloride ions penetration. The experimental results revealed that the use of 100% manufactured sand along with mineral admixtures in producing ready mix concrete is a good choice in view of the non-availability of river sand to meet the demands of fast-track construction projects.