Cement composition containing dune sand and limestone powder, concrete products and method for making concrete products

A method for producing a cast concrete product in which the steps consists of:

• a) providing red dune sand and limestone;
• b) grinding said red dune sand and said limestone to produce particle sizes of less than 45 microns;
• c) mixing the dune sand and limestone with cement, aggregate other than red dune sand, water and superplasticizer to produce a cement mix with about 40% dune sand powder and a range of Portland cement from 15 wgt. % to 45 wgt. % and limestone powder from 15 wgt. % to 45 wgt. %;
• d) casting the concrete mix in a predetermined shape by placing the concrete mix in a mold to produce a molded article;
• e) within 24 hours of casting, steam curing the molded article for 12 hours under atmospheric pressure;
• f) de-molding the molded article and placing the molded article inside a curing chamber and maintaining 100% humidity in the curing chamber;
• g) raising the temperature in the curing chamber to between 160° C. and 200° C. within two hours to thereby raise the pressure to 10 bars and maintaining the 180° C. temperature at 100% humidity within the curing chamber for 4 to 5 hours;
• h) releasing the pressure to reach atmospheric pressure within 20-30 minutes and the temperature is reduced gradually.