Gypsum Seting Time

g pic Faculty of engine room Civil engineering de disseverment ENCS 314 Building material lab prove No. 15&16 function of body of water supply nitty-gritty employ to effect gypsum samples and the determination of the final aspect for gypsum Prepargond by Rasha abed 1031107 Partners Hazem Noman 1060155 Mohammed Hashlamoun 1060173 Ehab Alawi 1051449 Instructor Ms. Randa Al- Asmar Date of experiment 25-03-2008 Date of submitting 01-04-2008 finish of water guinea pig used to throw standardized gypsum samples and the determination of the final setting for gypsum understructureIn civil engineering, gypsum plays a role as a twist material that contributes to many products such as cement and smear. In this experiment, we investigated close to properties considering hardening of gypsum, such as the standard water content and setting sequence. Aim of the experiment Determination of the proper water content to prepare gypsum facing pages samples Determination of the final setting time for gypsum paste. Theory normal water content make out of water added to gypsum to form a paste thatd allow the pointer of Vicats apparatus to descend to a point (30-32) mm above the groundwork of the decide.Setting time of Gypsum the amount of time that passes from the moment of adding water to the gypsum paste (would be already determined) to the moment that Vicats goad would descend to filtrate 3 mm above the base of the mold. Apparatus Determination of the water content Vicat apparatus Balance Metal tray Graduated cylinder Determination of the setting time for gypsum Vicats apparatus (the pointer is replaced by Vicats needle of 10 mm diameter. Stop watch 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 mixed 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 filled completely with the paste and the come forth of the mold is rimmed. 4. Vicats mold is applied on the base of Vicats gizmo. The pointer of the device is adjust to just touch the surface of the mold, then left to give freely under the influence of its weight. . The reading of Vicats pointer is taken. This reading indicates the depth that the pointer has reached above the base of the mold. 6. The experiment is repeated using a newborn 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 the 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 depth The amount Trial no. from the base (mm) of added water (%) 39 48 1 34 49 2 35 48. 3 32 50 4 50 sample water content (%) 4. 16 setting time (minutes) ConclusionAs 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 industry. 1 Engineering use Gypsum is considered real valuable from t he 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 new techniques have been developed get returns from gypsum and Portland cement. these techniques uses both the advantages of gypsum (early 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 formed when gypsum and Portland cement interact. Such properties enhance the workability of cement. 23References 1 http//www. knowledgedirect. com/science? _ob=ArticleURL=B6V2G-4BRRGD8-2=10=1==search=d=c=C000050221=1=0=10=4e71cbde7aba9b4d1338fea79920ab39 2 http//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