Microencapsulated Phase Changing Materials for Gypsum Plasters: A Practical Approach

Several studies have shown the feasibility and thermal potential of gypsum plaster with microspheres of PCM, but very few of them investigated an approach with practical and standards concern. In this work, different characterizations are performed according to European standards on a standard gypsum plaster and two different gypsum plasters formulated with 20 wt.% of PCM microspheres. A material is experimentally made by mixing conventional gypsum and PCM microspheres, whereas the other is an already prepared commercial mix. For the laboratory material, the addition of PCM increases the consistency of the fresh paste of plaster. In order to reach a consistency in agreement with the standards more water is required. This higher amount of water causes further issues on the densification and cohesion properties. In contrary, the properties of the commercial mix are closer to a common plaster. It is therefore assumed that the commercial material incorporates thinner additives. In view of these results, it is assumed that most of the drawbacks due to the addition of PCM microspheres in gypsum plasters could effectively be encountered by adequate addition of additives in order to reduce the amount of water, and binding resins in order to improve the adhesion and mechanical properties.

Additives Effects on producing Gypsum plaster in Zurbatiyah area, Eastern Iraq

Gypsum deposits are wide spread in Zurbatiyah area, Eastern of Iraq, especially in Fatha Formation. Gypsum deposits have been known as a suitable materials for gypsum plaster industry. Sawdust and Palm fibers powders have been added in different ratios to gypsum plaster material mixture to improve their industrial properties. Addition of 0 %,1 %, 5%, 10% and 15 % pass of 4.75 mm size of sawdust and palm fibers powder and 0 %, 1 %, 5%, 10% and 15 % pass of 5.60 mm size of sawdust and palm fibers powder to gypsum plaster material mixture. This ratios showed results of consistency (35-75 ml/gm), setting time (11-20 min) and compressive strength (2.2-4.4 N/mm2) for sawdust powders size 4.75 mm, whereas the results of consistency (35-63 ml/gm),setting time (11-21 min) and compressive strength (2.0-4.2 N/mm2) for palm fibers powders size pass of 4.75 mm. The addition of 1% and 5% pass of 4.75 mm sawdust and palm fibers powder to gypsum plaster material mixture showed an improvements in consistency(37-41ml/gm), (36-40ml/gm) setting time (13-14 min), (12-13 min) and compressive strength (4.2-4.4 N/mm2), and (4.1-4.2 N/mm2) for sawdust and palm fibers respectively. Also the addition of 1 % and 5 % pass of 5.60 mm sawdust and palm fibers powder showed consistency (40-45 ml/gm), (39-44 ml/gm), (14-15 min.), (12-13min.), (3.5-4.2 N/mm2), and (3.0-4.1 N/mm2), for sawdust and palm fibers respectively. In general, the results of current study conform the requirements of the Iraqi standard specification No. 28 (1988) and ASTM C28, C472 (2010) for ordinary gypsum plaster industry.

Influence of the Heating Temperature and Fineness on the Hydration and Mechanical Property of Recycled Gypsum Plaster

Influence of the heating temperature and fineness on the hydration and mechanical property of recycled gypsum plaster was investigated to find the suitable heating temperature and fineness. According to the results, the setting time of recycled gypsum plaster increased with the increase of heating temperature, and the mechanical strength increased first and then decreased at a temperature of 165°C. Therefore, the suitable heating temperature was 165°C, and at this time, the initial setting time and final setting time were 8 min and 12.5 min, respectively, which met the requirements of the Chinese standard of GB/T 9776-2008. The strength of recycled gypsum plaster increased with the increase of specific surface area, and the low water to plaster ratio and high strength were achieved when the specific surface area was 1526 m2/kg. Therefore, it can be concluded that the suitable heating temperature was 165°C and the suitable specific surface area was 1526 m2/kg considering the properties and economics of recycled gypsum plaster.

Sustainable Management of Autoclaved Aerated Concrete Wastes in Gypsum Composites

Promoting the use of gypsum and gypsum-based materials in construction is a successful strategy from an environmental point of view; it allows a lower energy demand with a sensible reduction in carbon dioxide emissions. At the same time, the manufacturing of gypsum products can represent an interesting sector to redirect and manage the large amount of autoclaved aerated concrete (AAC) waste. In this paper a sustainable application of AAC granulate waste in gypsum-based building materials was proposed. The intrinsic compatibility derived their chemical composition and allowed it to partially substitute raw gypsum with the waste up to 30% without affecting the functional and structural properties of the final product. Physical characterization and sound absorption data confirmed that the addition of AAC waste does not significantly alter the typical porosity of the gypsum composite. Finally, all of the composites reached mechanical performances suitable for different building application as gypsum plaster.

Physico-Mechanical Properties of Plaster of Paris (Gypsum Plaster) Reinforced with Paper Pulp

The study was carried out on the physico-mechanical properties of plaster of Paris (Gypsum plaster) reinforced with paper pulp in order to improve the weight of plaster paste and to obtain materials of lighter weight that solve problems such as poor flexural strength, and crack propagation. To do this experiment, the considerable basis of a standard of 2 kg of plaster of Paris was taken as the test sample. Gradually plaster of Paris was substituted with paper pulp paste in a water basin in proportions K0, K1, K2, K3, K4, K5 and K6 representing the different percentages of 0%, 10%, 20%, 40%, 60%, 80%, 100% of mixture respectively. After the above observations, the following parameters on fresh and hardened samples were tested: the start time of reaction, and end time of hardening, consistency, the flexural and compressive strength, shrinkage, and apparent density. At the end of these tests, it was determined that, the incorporation of small amounts of paper pulp (2 kg samples) into the plaster paste improves its flexural properties. But from k0 to k6, properties related to bending and compression began to gradually fall which is a consequence of the augmentation of the amount of paper paste in the plaster paste. The presence of paper pulp in the plaster of Paris paste increases the time of hardening of the plaster cement from one proportion to another, reduces the workability of the mixed paste, significantly solves the problem of removal, the apparent density drops when waste paper paste is increased in the mixed plaster. Because of its light weight, low density, its acceptable Mechanical properties, these new materials are recommended for exploitation in the manufacturing of popular lightweight construction finishing like panels for ceiling or walls, staff works and other applications.