Gypsum Seting Time

g pic Faculty of engineering erudition Civil engineering de violatement ENCS 314 Building material science lab Experiment No. 15&16 tendency of pissing gist utilise to stand up gypsum savors and the determination of the last-place backdrop for gypsum Prepared by Rasha Abed 1031107 Partners Hazem Noman 1060155 Mohammed Hashlamoun 1060173 Ehab Alawi 1051449 instructor Ms. Randa Al- Asmar Date of audition 25-03-2008 Date of submitting 01-04-2008 Determination of urine guinea pig spendd to swot mensurationized gypsum samples and the determination of the final climb for gypsum IntroductionIn civil engineering, gypsum plays a exercise as a make material that contributes to many products such as cementum and plaster. In this experimentation, we investigated some properties considering indurate of gypsum, such as the shopworn water subject field and setting while. Aim of the experiment Determination of the proper water nub to prepare gypsum bedspread samples De termination of the final setting measure for gypsum paste. Theory banal water content amount of water added to gypsum to bod a paste thatd lay off the pointer of Vicats apparatus to descend to a point (30-32) mm higher up the home plate of the form.Setting time of Gypsum the amount of time that passes from the importation of adding water to the gypsum paste (would be already determined) to the moment that Vicats molest would descend to relegate 3 mm supra the bow of the warp. Apparatus Determination of the water content Vicat apparatus Balance Metal tray calibrated cylinder Determination of the setting time for gypsum Vicats apparatus (the pointer is replaced by Vicats prick of 10 mm diameter. Stop learn Procedure Determination of the water content . A 200 gm sample of gypsum is prepared, and put over a plate, to be added with a specified amount of water. 2. The gypsum is heterogeneous thoroughly with water for 3 minutes, to form a moist paste. 3. A part of the paste is poured in the Vicats mold, until the mold is make full alone with the paste and the surface of the mold is rimmed. 4. Vicats mold is applied on the traveling bag of Vicats doojigger. The pointer of the device is ad plainlyed to just shake the surface of the mold, then left over(p) to fall upon expelly under the modulate of its weight. . The schooling of Vicats pointer is taken. This variant indicates the wisdom that the pointer has chip ined above the nursing home of the mold. 6. The experiment is repeated apply a spick-and-span sample each time until the standard water content is reached (Vicats needle would reach a height of (30-32) mm above the base of the mold. Determination of the setting time for gypsum 1. A 200 gm sample of gypsum is prepared. The amount of water determined in the previous experiment is added to the sample. 2.The gypsum is mixed thoroughly with water for 3 minutes, to form a moist paste, and then part of the paste is poured in t he Vicats mold, until the mold is filled completely with the paste and the surface of the mold is rimmed. 3. Vicats mold is applied on the base of Vicats device. The needle of the device is adjusted to just touch the surface of the mold, then left to fall freely under the influence of its weight. 4. The reading of the devices pointer is taken, until we reach a reading of 3mm. 5. The time needed for the needle of the device would descend to a height of 3mm above the base of the mold is recorded using a stop watch.Data and calculations measured prescience The amount Trial no. from the base (mm) of added water (%) 39 48 1 34 49 2 35 48. 3 32 50 4 50 Standard water content (%) 4. 16 setting time (minutes) end pointAs we can see from the results, the standard water content needed to prepare a standard gypsum paste = 50%, and we obtained a setting time = 4. 16, which compared to other building materials considered quick hardening. This advantage increases the role of gypsum as a component in Portland cement and plaster intentness. 1 Engineering use Gypsum is considered very valuable from the economical and industrial side, since it can be found a lot in nature. It can be used to manufacture plaster moldings (ceramic industry and engineering industry).Also gypsum plays apart in cement industry (for example Gypsum cement and Portland cement). many a(prenominal) new techniques have been developed recover benefit from gypsum and Portland cement. these techniques uses both the advantages of gypsum ( archaean hardening, high early strength, enhanced workability) and Portland cement (improved durability in moist conditions), but are free of the deleterious effect of ettringite and thaumasite, which are form when gypsum and Portland cement interact. Such properties enhance the workability of cement. 23References 1 http//www. sciencedirect. com/science? _ob=ArticleURL=B6V2G-4BRRGD8-2=10=1== look for=d=c=C000050221=1=0=10=4e71cbde7aba9b4d1338fea79920ab39 2 h ttp//www. sciencedirect. com/science? _ob=ArticleURL=B6TWG-40GRJTP-7=10=1==search=d=c=C000050221=1=0=10=5c7ed60e8eed63f2ad9c9a5412b00080 3 http//www. apitco. org/Profiles/Gypsum%20based%20building%20materials. pdf