Preparation And Properties Of Buildingmaterials From Desulfurization Gypsum

In this research we used the desulfurization gypsum.The FGD gypsum was present in semi powdered form;so it was first grinded and later passed through the sieve of 0.8mm to get the powder form of FGD gypsum.When it was totally converted into powder the physical and chemical properties of FGD gypsum were analyzed;lately the powder gypsum was used in making of blocks.First of all the powdered gypsum were put in the dry oven on the temperature of 60℃ for 24h then the different tests were conducted on the dry gypsum such as the XRD X-ray diffraction and SEM scanning electron microscope.Through XRD and SEM tests it was observed that 170℃ is the best temperature for drying of FGD Gypsum.Then the FGD Gypsum was passed through the heating treatment process at different temperatures at different time intervals such as 150℃,170℃,190℃and 200℃ for 1h,1.5h,2.5 and 3h.The Standard Consistency water test was applied by Vicat apparatus to know the amount of water mixed with the FGD Gypsum.The basic measurement was 100g of FGD Gypsum mixed with 70g of water.The initial time for best result was 2-3 minutes and 45-50 minutes for final time.Adopting the best retention time for the preparation of block has been started in which lkg FGD Gypsum was mixed with 700g of water for 20 seconds to 25 seconds through driller machine and was put in the steel type mould for 5 to 15 minutes.For the easy extraction of block from mould oil was used on the sides of the mould.The blocks were put in 3 conditions for dryness.Such as i.natural(Sun light)dryness,ii.Room temperature dryness,iii.Oven dryness.The blocks in natural and room temperature dryness the blocks were kept for 3 weeks and for oven dryness the blocks were kept in oven for 24 hours.After that 2 tests were applied on the blocks one was compressive test and other was breaking strength test.7.8271 KN;more than 50 KN and retention time was nearly 100 sec.From the results it was proved that the natural dry block has the best binding capacity and has the highest breaking strength.Over all the tests of naturally dry block showed better results comparing with the other dry blocks.