Papers by Keyword: Gypsum Plaster

Abstract: In view of the climate emergency and the need for energy transition, the use of materials with low environmental impact based on plant co-products or from recycling is strongly encouraged. Biobased materials have been developed in recent years and have shown interesting performances, particularly for the thermal insulation of buildings. Nevertheless, their use is still hampered by the lack of rules for their use and control of their behaviour in normal or accidental conditions of use such as excess water or fire. In this work, the behaviour of biocomposites based on cereal straw exposed to high temperatures was studied. The objective is to evaluate the effect of this temperature increase on the mechanical strength of the material and its thermal properties using different heating scenarios. The biocomposites considered for this study were developed as part of the PEPITE project funded by the “Region Centre Val de Loire”. They are materials composed of two different binders: lime, and plaster, straw aggregates and additives (air entraining agent, casein protein and biopolymer). In order to simulate fire, two temperatures were chosen for the study 200°C and 210°C, using four different heating rates to study their impact on the behaviour of dry and wet conditions of biocomposites. The purpose of this tests is to examine whether the material retains its insulating properties and its buildability. The results showed that the use of additives had negative effects on the behaviour of the materials with respect to temperature increase. Their use accelerates the degradation and burning of biocomposites faster than for samples without additives. Plaster based composites show a better behavior to high temperature than lime-based composites. Nevertheless, lime composites have a higher strength than plasters. Furthermore, the thermal conductivity of plaster is lower than that of lime. It should be noted that the heating rate has a significant impact on the behaviour of the material, the slower the rate, the more the material is degraded.

Abstract: In this article the self-hardening structure of stone based on calcium sulfate formation is described. Increase of strength of gypsum is possible by additional reinforcing of a stone ettringite crystals. The form and character of the formed crystals is defined by size рН. Dependence рН from the maintenance of additives was investigated in work. The limiting factor of formation of crystals of an ettringite of a necessary look is the maintenance of an additive. In work gypsum composites with the improved physical-mechanical properties on the basis of the modifying complex are received and investigated.

Abstract: Fire resistance of building structures is important not only in terms of prevention of hazards to human health, but also from the economic point of view. The choice of method of fire protection of steel structures depends on the responsible choice of finish or cladding material and suitable technology implementation. Although the assessment of fire risk is a priority, when selecting the decisive criteria we must not also forget the cost of fire protection measures. This article aims at economic comparison of the two fire protection measures for the steel column of rolled profiles.

Abstract: This study investigates the influence of limestone powder and silica flour used as fine mineral fillers on the main characteristics of gypsum plaster. Fine mineral fillers were added in various dosages from 2.5% to 20.0%.

Abstract: Gypsum waste from building constructions is a material which can contaminate the soil and groundwater if is disposed directly in the soil or landfill without any control. In Brazil, these wastes are considered a recycle and/or recovery material, but the research of gypsum plaster recycling are very few at this moment. In this way, this work presents the microstructural characterization of two types of recycled plaster. The recycled plaster was produced by a grinding and calcination the building construction waste. Microstructural characteristics were evaluated by SEM observations. The results show similarities between crystals of recycled and commercial plasters.

Abstract: People in the developed world require comfortable indoor climatic conditions. In the summer time there is often risk of the overheating of buildings, especially buildings with lightweight envelope. Requirements for interior temperature are not summarized in one piece of legislation, but parameters of indoor environment are set according to the type of using of internal space by various laws, regulations, standards and other regulations. Passive cooling can maintain a state of indoor environment in the required temperature range in accordance with legislative framework. Presented system uses phase change materials as a latent heat storage medium for better absorption of heat. The tested system combines the latent heat storage material in the form of micro pellets, which are dispersed in the gypsum plaster, and capillary cooling for their activation so that the secondary effect is possibility of a direct radiant cooling of the room.

Abstract: This article addresses the design of a new photocatalytically active gypsum plaster. A hemihydrate in beta type is used as binder to design this material and a carbon modified TiO₂ that can be activated by visible light is used as photocatalyst. An own developed test setup to assess the indoor air purification capacity of the developed material is presented. The new product possesses the indoor air pollutants removal capacity. The air pollutants removal ability is related with not only the dosage of the applied photocatalyst but also strongly with the physical property of the resulting matrix such as the porosity.

Abstract: Construction and demolition waste has in its composition gypsum plaster which is a soil and groundwater contaminating material. Some works have been developed to recyle this gypsum waste. The aim of this work is to show a thermal analysis of recycled plaster. The recycled plaster was produced through a recycling process consisting of grinding and burnig the gypsum waste. Physical and thermal properties (TGA/DTA) from both commercial and recycled gypsum plaster were analysed. The results show a recycled plaster with similarities with commercial plaster, showing the possibility to reuse this waste in construction works.

Abstract: To understand the water transport properties and generally the mass and heat transfer performance, the sorptivity of different building gypsum plasters are investigated by experiments. The sorptivity of five kinds of gypsum materials are measured and compared with that of fired clay brick. The effects of water/plaster ratio, wet/dry cycles and lightweight additives on the absorbing properties are investigated. The “square root of t” law and the validity of sharp water front (SWF) model are also analysed. It is concluded that the absorption properties of gypsum plasters are sensitive to premixed lightweight aggregates, water/plaster ration and wet-dry cycles

Abstract: Flue gas desulphurization (FGD) gypsum and fly ash are two kinds of solid waste in coal-fired power plant. The possible displacement content of fly ash in gypsum plaster was investigated in this paper. The effect of various chemicals retarders, such as Citric acid, sodium citrate and SC gypsum retarder, and water retention agent on the setting time, flexural strength and compressive strength of gypsum plaster was also studied. The results demonstrate that gypsum plaster has maximum mechanical properties and enough setting time at the rate of 20% fly ash replacing calcined gypsum; SC gypsum retarder effectively delays the setting time and has lower strength loss; The optimum level of water-retention agent for effective utilization of gypsum plaster is 0.2%.