Krishna Udyog offers ‘Rapidex’ additive for manufacture of cement. Rapidex is very useful for achieving high early strength of cement and can be used as additive for manufacturing Portland slag cement, Portland pozollana cement, ordinary Portland cement and composite cement. Rapidex is a mineral admixture of amorphous, calcined silica and alumina which reacts aggressively with calcium hydroxide to form compounds with cementatious value that are blended or inter-ground with cement. It enhances the performance of cement characteristic properties and resistance under aggressive environment. The performance enhancing properties of Rapidex are achieved through two principal mechanisms. One is physical effects. The extremely fine particles of Rapidex are able to fill the microscopic voids between the cement particles, improving packing and creating a less permeable concrete structure. The second is in the curing process, the silica reacts with the free calcium hydroxide produced to form additional calcium silicate hydrate (CSH), and enhance cement to aggregate bond. The filler effect plays a major role in controlling bond by modifying the properties of fresh concrete to reduce internal bleeding, voids and transition zone. The Rheological properties of concrete play a major role in developing high early strength. The compressive strength of cement mortar cube of PSC & PPC with Rapidex (1.5 per cent) for 1, 3, 7 and 28 days are shown in enclosed sheet. The advantage of Rapidex include increases high early strength in 1, 3 and 7 days and continuous gain of strength till 28 days, reduces clinker consumption by 5 to 10 per cent (depends on the quality of clinker), water impermeability, enhance surface definition, bleeding prevention, resists from chemical attack and prevent from alkali silica reaction in concrete, no effect on LOI and IR, free from chloride, alkali and sulphate, reduces shrinkage in concrete, work as air entraining agent,etc. Krishna Udyog Kolkata, West Bengal Tel: 0342-256 8638, Fax: 0342-255 9855 Email : krishna_udyagbdn@yahoo.com