Gypsum Composites Research Articles

Growth-zoned gypsum stalactite from the Kawah Ijen volcanic lake, Indonesia, records a >40-year record of volcanic activity

Volcanic crater lakes represent both a significant hazard and an opportunity to monitor the activity of their host volcano. Unfortunately monitoring efforts, especially of lake water composition, are commonly limited by the lack of a historical record. Here we report the results of a study on the Kawah Ijen crater lake in eastern Java, Indonesia that uses growth-zoned gypsum precipitated from lake water seepage as a proxy record of lake water chemistry. Absolute ages for gypsum growth zones were determined from 210Pb radionuclide dating with a newly developed Ar-Kr-Xe correction for variations in the volcanic flux. The resulting 40-year time series of gypsum composition shows that periods of unrest are recorded by large compositional variance, whereas quiescence is characterized by low concentrations and low variance. Gypsum associated with the 1817 phreato-magmatic eruption of Kawah Ijen is similar in most elements, but it has markedly higher ratios of Cu over Sb, As and Tl, which is interpreted to represent a volcanic gas signal. These results show that gypsum holds great promise to provide the missing historical record of lake chemistry and unrest at Kawah Ijen volcano, and this approach can be extended to other volcanoes hosting crater lakes where gypsum is present.

Improving the Properties of Filled Gypsum Composites by Carbonization

Carbonization of modified composites based on gypsum binder has been proposed as a promising method for producing gypsum materials with high technical properties. To reduce costs and improve manufacturability, mineral modifiers are used in gypsum composites. Together with gypsum and lime the waste of basalt production is used. In contrast to other methods, the proposed carbonization during the formation of gypsum forms a gypsum stone, which has a reduced porosity. Of particular interest is the clogging of external pores, which communicate with the external environment. It is these pores that reduce the water resistance of gypsum composites. The formation of carbonate phases in the structure of gypsum stone will help improve the performance of the material. At the same time, the problem of preserving the natural environment for future generations is being solved. It also increases the economic and environmental attractiveness of the project

Improvement of Arbolit Concrete Bio-Resistance with Additives by Nanomodificators

Arbolit concrete, as one of the types of light modern concretes, is a complex composite of a combination of different materials: a binder component, additives and cellulose aggregate. Wall blocks, panels, slabs, etc. are manufactured from arbolit concrete for the construction of low-rise residential, public, industrial and agricultural buildings. According to the properties, arbolit concrete is closest to the tree (organic aggregate is more than 85% of the volume). Arbolit concrete combines the best qualities of wood and concrete: environmental friendliness and durability of concrete, strength of wood and its vapor resistance. However, cellulosic aggregate has its own specific features that negatively affect the structure formation processes, in particular, the strength and durability of the composition “ organic aggregate - astringent "to moisture-variable effects. Selection of a binder for arbolit concrete is also a difficult task that requires a separate research. Basically, for the manufacture of products made of arbolit concrete portland cement is used, abroad - lime binder. The disadvantage of cement concrete on cement, lime and lime containing a binder is a relatively long period of gain of brand strength. A promising direction for solving this problem is the use of composite gypsum binder for the production of concrete. Based on the above, we can conclude that the design of low-density arbolitbeton formulations on a composite gypsum binder is an urgent task [1].

Research of toxicological safety of production and operation of products from sulfur gypsum composite

By spent researches is established, that the products from a composite material on a basis gypsum and sulfur do not include in the structure potentially dangerous for organism of the person and environment of connections of mercury, thallium, selenium, arsenic; are chemically stable and do not allocate in inducing air, water and acid of environment unstable of inorganic connections. By manufacture of products on air environment of a working zone can be allocated hydrogen sulphide and sulphureous anhydride, that requires the appropriate organization of labour of the workers with maintenance of a premise by compulsory ventilation and measures of fire-prevention safety.
 Toxicological and hygienic studies of powdered sulfur gypsum material in case of cutaneous admission (50% vaseline emulsion) allowed to establish the following: after the first application of the paste, no visible changes were observed on the skin of animals. After ten applications in 2/3 of the experimental animals, pale pink erythema was observed throughout the paste application area. With further applications, the intensity of skin hyperemia did not increase. The resulting changes can be classified as a moderately pronounced skin irritating effect of powdered sulfur gypsum material.
 Analysis of the information obtained during the formulation of basophil degranulation reactions and specific agglomeration of blood leukocytes of guinea pigs sensitized with powdered sulfur gypsum material indicates the absence of statistically significant changes in the parameters of the studied reactions in animals of the experimental and control groups. This gives grounds for concluding that sulfur gypsum materials do not possess allergenic activity.
 Based on the conclusion of the Chief Sanitary Doctor of Ukraine, a composite material based on gypsum and sulfur is recommended for the manufacture of tiles that can be used in the construction of buildings of “B” and “V” groups (industrial and public buildings).

MANUFACTURE OF MODIFIED ARBOLIT FROM LOCAL RAW MATERIALS: OPTIMIZATION OF COMPOSITION AND PROPERTIES OF RAW MATERIAL COMPONENTS

Introduction. The creation of energy-saving materials involves the use of local raw materials for products with improved physic-mechanical properties. The author carries optimization of the rational composition and properties of modified arbolite from plant-gypsum composition (PGC). In addition, the author uses modifiers on new ways of preparing the aggregate according to the method of experimental and statistical modeling.Materials and methods. The author used the cereal straw grown in the Kyrgyz Republic (CS), G-5 and G-7 construction gypsum based on local raw materials, ash from the Bishkek Heat and Power Plant (BHPP), portland cement clinker PCC, natural clay (ganch). Moreover, the clay component of the Toloykonsky deposit was used as the clay component. The author also added the liquid glass, latex SCS, the low-concentration resin LCR-3066 + catalyst of ionic type (CIT) as modifiers for the formation of the porous polymer-silicate systems. The paper marked the plasticizing additives in the manufacture of arbolite as SCS, LCR and CIT components. As a retarder the setting of gypsum was added a partial salt 1-hydroxyethylidene-1, 1-diphosphonic acid with triethanolamine and flame retardants. The tests were carried out according to standard methods. To optimize the composition and properties of the polymersilicate-gypsum composition (PSGC), the author carried out a three-factor experiment according to the B3 plan, where three prescription factors varied: X1 – straw content,%; X2 – content of polymer silicate additives (PSA) + plasticizer,%; X3 – gypsum content + portland cement clinker as a nitroperimethyl phosphoric acid (NPA) and flame gypsum retarder.Results. The research showed that at 28 days of age for cement-free gypsum compositions as the content of straw increased, the strength was almost unchanged. When comparing the strength of the same samples of 2 and 28 days strength with the maximum filling of gypsum, the author defined that the PSA content should not exceed 12% when the straw additive was 26% and further PSA increasing did not increase the strength.Discussion and conclusions. As a result, the author achieves maximum strength of the arbolit, when the content of G-7 gypsum is 28-32%, ash is 18-22% and PSC is 8-10%. The maximum value of strength and water resistance of the material is achieved with a rational ratio of components: straw – 24–28%, G-7 gypsum – 30–32% + NSPL – 0,05%; ash – 18–22%; resin – 3066-8-12% + catalyst – 0,3% (87% sulfuric acid, 13% phosphoric acid); PCC – 3–5%; clay-gypsum (ganch) – 2%; liquid sodium glass – 12%; plasticizers CIT – 0,15%, SCS – 0,2%, LCR – 0,15%; modified hardener – 0,5% and water.

Performance of ternary gypsum-based mortars in wet environment

Gypsum is one of the most environmentally friendly materials, but it could be used only in the dry environment. When gypsum is wet, its mechanical properties worsen substantially and namely its strength decreases significantly. Ternary gypsum-based binders, composed from gypsum, lime and pozzolan evince better resistance against the moisture, because water-resistant phases are created as products of pozzolanic reaction. The behaviour and properties of several gypsum composites with different types of pozzolans, exposed to the moisture, were investigated. Samples of ternary composites were stored in the water for 360 days and their properties were tested during the period and compared with the properties of gypsum mortar. While gypsum mortar degraded significantly, the ternary mortars retained its properties and the strength of some of them even increased.

Properties of Gypsum Composites with Straw Fillers

Results of tests of physical and mechanical properties of gypsum composites with organic fillers, in the form of cut straw are presented at the paper. The conducted tests aimed at determining the influence of gypsum mixtures composition and the manner of filler’s preparation on the quality of composites. Strength and thermal properties, natural radioactivity and susceptibility to biological corrosion have been examined. The results were interesting. Moreover using straw as a component of gypsum mixtures is particularly friendly for natural environment.

Impact of Wetting-Drying Cycles on the Mechanical Properties and Microstructure of Wood Waste-Gypsum Composites.

Large amounts of wood waste are generated each year in the world. In an attempt to identify a good recovery option for those residues, wood waste from construction and demolition works were used as raw materials in gypsum plasters. However, wood is a biodegradable material which implies that the products or materials that contain it are susceptible to suffering an important deterioration, due to exposure in certain environments. For that reason, the aim of this work was to simulate the effects that, in the long term, the atmospheric exposure of wood waste–gypsum composites would have. To do that, the plasters were subjected to 5, 10, and 15 wetting–drying cycles in a climatic chamber. In this study, the density, flexural and compressive strength, and ultrasonic velocity of these composites were determined by the influence of the aging process on their mechanical properties. Furthermore, in order to detect changes on their internal structure, scanning electron microscopy tests (SEM) were used. The results showed that they were suitable to be used as indoor coverings of buildings. However, a treatment to reduce the moisture absorption of the wood waste must be studied if mixtures with high percentages of wood shavings (WS20) are used in wet rooms.

Ignitability small attack flame fire test of gypsum composite reinforced with natural fibres

Ignitability is one of the parameters that characterize the behaviour of building materials on flame action. The Ignitability Small Attack Flame fire test is used for the classification of building products by their reaction to fire. On the basis of the Ignitability fire test it can be determined that the tested material will be classified into the class E by reaction to fire. The Ignitability Small Attack Flame fire test precede the Single Burning Item fire test, that is used for classification of building products to class D, C, B, A2. The results of the Ignitability fire test were carried out as part of the research on the properties of gypsum composite with natural fiber reinforcement. As part of the research series of ignitability tests on two types of gypsum composite were carried out. The first type was a gypsum composite reinforced with straw fibres. The second type was composite reinforced with wooden fibres. Developed composite materials could be used in the future as board materials and therefore the determination of their fire parameters is a very important part of research. The results of the fire tests have shown that the developed material has a very good flame resistance.

Mechanical properties of the gypsum composite reinforcement with wooden fibers

The gypsum is one of the most often used materials in the civil engineering. Very often it is applied in the form of plasterboards without any reinforcement, for example, cladding boards are unusable as supporting construction. To improve the mechanical properties of plasterboards, fibrous materials such as cellulose or glass fiber are added. Reinforcement of gypsum with fibers improves in particular the flexural and shear strength. The main purpose of the research is to clarify whether natural wooden fibers could be used as the reinforced of composite gypsum building materials. Wooden fibers are used as a blown or board thermal insulation. This article presents the results of tests aimed at determining the mechanical and physical properties of gypsum composite reinforced with wooden fibers. The effect of the reinforcement on the strength properties as a compressive strength, flexural strength was verified on a series of test specimens. The results of the tests have shown that the reinforcing of gypsum composite has an impact on the mechanical-physical parameters.

Synergistic effect of mineral admixture and bio-carbonate fillers on the physico-mechanical properties of gypsum plaster

The present study proposes a new strategy to develop a composite gypsum binder with enhanced strength and stability using mineral admixture (zeolite) and bio-carbonate fillers (waste shell powders). The produced gypsum composites were experimentally investigated to study the synergistic effect of zeolite (natural and calcined) and shell powders (egg, conch, cuttlebone and scallop) on the physical and mechanical properties of gypsum composites. The mechanical strength evaluation showed desirable results due to the filling ability as well as reinforcing property of the shell powders when used in combination with zeolite. In addition the natural zeolite acted as internal curing agent and enhanced the gypsum hydration due to their water imbibing quality thus providing high water of crystallization for gypsum formation. The calcined zeolite acted as densifying agent and improved the water stability and reduced the total porosity of the gypsum matrix. The X-ray diffraction studies and IR spectroscopic results showed well hydrated crystalline gypsum dihydrate phases and the SEM images showed significant improvement in the morphology of the plaster leading to enhanced water and thermal stability. Thus the proposed design strategy proves to be a technical solution for the production of high performance gypsum composites utilising the binding capacity of zeolite and filling ability of waste shell powders.

The Development of Composite Nanostructured Gypsum Binder with Enhanced Heat Resistance Performance

The subject of this study was an experimental confirmation of stability of composite nanostructured gypsum silicate binder (CNGSB) system under high-temperature exposure (up to 1000 °C). The hypothesis of the heat-resistance performance of gypsum-based binder was crystallization process in CNGSB system involving a silicate constituent as a reactive component in NB. XRD and DTA analyses demonstrated that thermal exposure of CNGSB to wide range of temperatures of 20–1000 °C leads to α-quartz to β-quartz phase transformation in the binder; amorphous alkali-aluminosilicate (gel) changes to crystal phase of Са-albite. The calculation of cell volumes characteristics for low-temperature (before thermal exposure) and high-temperature (after thermal exposure) phases was performed. The calculated ratios of unit cell volumes were close to 1 which ensures a structural stability of the GNB under thermal exposure and confirms its heat-resistant performance.

Properties of Composite Gypsum Binders Depending on Multicomponent Mineral Additives

This article considers the possibility of increasing the effectiveness of composite gypsum binders (CGB) by controlling the processes of structure formation as a result of using new types of multicomponent mineral additives that are significantly different from the traditionally used quartz raw materials:- waste of wet magnetic separation of ferrous quartzites (WMS waste,) of polymineral composition with quartzy of varying degrees of crystallinity, nanodispersed silica and chalk powder. We have studied the cause-effect relationship between the change in the ratio of binding and mineral additives of various compositions, which determines the conditions for the formation of technological and strength characteristics of the projected composite materials with specified performance properties. We have established the presence of regularities in the changes in the properties of CGB, the composition of the hardening products and the microstructure depending on the type and content of gypsum binders of β-and α-modifications, portland cement, multicomponent finely-dispersed mineral additives, the regularity consists in the binding of portlandite, which is released upon portland cement hydration, by the amorphous phase of earth siliconas a part ofnanodispersed powder and chalcedony variety of quartz waste of wet magnetic separation of ferruginous quartzites. This provides a reduction in the basicity of the solidifying system, the intensification of crystal formation, and the formation of newgrowths with a high content of tobormorite-low-basic calcium hydrosilicates that compact the microstructure of the hardening matrix and, as a result, increase the water resistance and stability. It is noted that this mechanism of hydration of CGB minimizes inner stresses and volume deformations, therefore the number of microcracks decreases, which leads to an increase in its efficiency in comparison with the traditionally used gypsum binder and that differs from the traditional portland cement by a fast strength generation.

Cost optimization of Colored Gypsum Composites

Gypsum composites as decorative and construction elements have been widely used for many building types due to their certain architectonic styles. Decorative gypsum composites are not very durable and stable when compared to the other composites; therefore, they need to be rehabilitated in short periods. To meet the increasing demand in the sustainability of these types of composite, many researches have been conducted for improving its properties with the minimum cost. The aim of this study was to obtain the optimum cost of the colored gypsum composites with the improved mechanical properties. Glass fiber reinforced, silica and expanded perlite reinforced gypsum composites were colored with the addition of brown, yellow, black and red pigments. The mechanical properties such as compressive strength and freeze thaw (F-T) resistance of the mixes were also examined. A cost optimization analyze were performed based on the experimental test results. Results revealed that the usage and the cost of the color pigment added gypsum composites can be primarily optimized.

Influence of polycarbonate waste on gypsum composites: Mechanical and environmental study

This work analyzes the influence of added plastic polycarbonate waste from recycled compact discs (CDs) and digital optical disc (DVDs) on the mechanical and environmental properties of composites with a gypsum matrix. Fifteen mixtures were produced including different percentages by weight of plastic aggregate with two different granulometries. In each case, the strength properties (flexural and compressive) and density of the new composites were tested. In addition, scanning electron microscopy (SEM) and X-ray computed tomography (XCT) were performed in order to know the internal structure and porosity of the new composites. Finally, a simplified environmental study was conducted using the Life Cycle Assessment (LCA) method. The results show that lighter and more eco-efficient materials can be obtained that have, in some cases, better mechanical properties than the reference material (gypsum). A density reduction of a 9.89% was achieved for mixtures with 60% of plastic waste, having also an environmental improvement of 35% compared to the reference sample. In all the cases, the minimum values for mechanical properties required by the standard were obtained. These properties make the composites suitable for use in new products and in construction works.

Influence of the heating process on the use of gypsum wastes in plasters: Mechanical, thermal and environmental analysis

Gypsum is widely used in the construction sector in internal coatings. The fact that the chemical composition of gypsum does not change makes the material fully and eternally recyclable, potentially solving the important problem of the large amounts of gypsum waste that each year go to landfills. Up to now, most of the works that use gypsum wastes subjected the material to a previous heating process. This implies a significant energy consumption, reducing the environmental benefits of the recycling process. This paper shows the second part of a research on which two different types of gypsum waste were used as a substitute of commercial gypsum: gypsum waste from industrial plasterboard production and flue gas desulphurization gypsum from a thermal central plant. In this research, the influence of the heating process on the development of new gypsum plaster composites containing different types and contents of waste was studied. Their mechanical properties and thermal conductivity were determined and a brief environmental analysis, using the Life Cycle Assessment method, was carried out.Based on the findings of this paper, it is confirmed that it is possible to substitute 100% of commercial gypsum with gypsum waste from industrial plasterboard production without any heating treatment, but maintaining a good performance. With this action, apart from the benefits in terms of environmental impacts, a slight improvement in the density, mechanical properties and thermal conductivity of the plaster was obtained.

Composition and rheological characteristics of plaster mixtures

The applying of local building materials is an effective contribution to the savings of mineral resources, which are used for the production of basic building materials. Clay and gypsum compositions are the local raw materials in many regions of the country and some neighboring countries. The article discusses the method for determining the clay fraction in the clay and gypsum composition, as well as the method for assessing the rheological characteristics of the plaster mixtures for interior work based on clay and gypsum binder. It was established that the content of the clay fraction in the studied clay and gypsum composition is in the range of 30–32%. Plaster mixtures based on clay and gypsum binder can be considered as optimal compositions under the following conditions. The grade of mobility is not less than PK3 (8–12 cm) in cone penetration test, the ultimate shear stresses in the first seconds of the thixotropic hardening ensure no runoff for the adjusted thickness of the applied layer. With the mentioned mobility, the “creeping” on the concrete surface is 10% and less, and the “creeping” on the brick surface is no more than 5%. The allowable water-solid ratio is 0,46–0,50.

Properties of gypsum composites with sawdust

Gypsum composites have been gaining increasing interest within last decades. Nowadays, the environment-supporting options are regaining more advocates. Thus, organic fillers are back in game. The physical and mechanical properties of gypsum composites with sawdust were tested and are described in the paper. The influence of gypsum mixture composition, the water/gypsum ratio and appropriate mineralization on the composite properties were examined. Present study focuses on the durability, thermal properties, natural radioactivity and susceptibility to biological corrosion of the tested materials.

Sulfur (34S/32S) isotope composition of gypsum and implications for deep cave formation on the Nullarbor Plain, Australia

Sulfur (34S/32S) isotope composition of gypsum and implications for deep cave formation on the Nullarbor Plain, Australia

Activation of Metallurgical Dust to Modify the Properties of Gypsum Compositions

Activation of Metallurgical Dust to Modify the Properties of Gypsum Compositions