Gypsum Matrix Research Articles

Enhancement of fresh properties and performances of the eco-friendly gypsum-cement composite (EGCC)

The area of application of gypsum materials is limited to low values of compressive strength, water resistance and durability. An urgent task is to increase the efficiency of the gypsum composite using Portland cement, as well as natural and industrial waste. In this work, complex studies were carried out, including scanning electron microscopy (SEM) images, differemtial-thermal analysis (DTA) and X-ray diffraction (XRD) patterns, small-angle X-ray diffraction, as well as mechanical and durability tests of hardened composites. The influence of gypsum building materials on the environment and humans throughout the life cycle have been determined. The features of the formation of the structure and hardening of the eco-friendly gypsum-cement composite (EGCC) have been studied taking into account the chemical, structural and morphological features of dihydrate gypsum, Portland cement, opoka, perlite and six different modifiers. The effect of various finenesses of grinding components on the performances of the EGCC has been investigated. It has been revealed that the maximum compressive strength of 18.1 MPa of hardened gypsum cement binder is achieved with a specific surface of 600 m2 / kg, a further increase in the specific surface leads to a decrease in compressive strength, which is explained by an increase in water demand. Comprehensive chemical additives have been developed that allow a wider range of setting time, from 35 to 72 min. With the introduction of a complex chemical additive, the volume of micropores decreases, which is due to small-sized new growths located in the pore space of the gypsum matrix. All this leads to improving fresh properties and performances of the EGCC.

Characterization of Gypsum Composites Containing Cigarette Butt Waste for Building Applications

Cigarette butts are one of the most common waste on the planet and are not biodegradable, so they remain on the landscape for many years. Cigarette butt composition makes it suitable to be added during the manufacture of construction materials, so it can be considered a waste recovery material, helping to reduce the ecological footprint of the construction sector. This article shows the characterization of gypsum composites containing cigarette butt waste. Several gypsum specimens were prepared incorporating different percentages of cigarette butt waste (0.5%, 1.0%, 1.5%, 2.0% and 2.5%). Samples without waste additions were also prepared in order to compare the results obtained. Samples were tested for density, superficial hardness, flexural and compressive strength, bonding strength and acoustic performance. Results show that it is possible to add cigarette butts in a gypsum matrix, resulting in better mechanical behavior than traditional gypsums.

Production of hemp-gypsum composites with enhanced flexural and impact resistance

This work aims at designing, manufacturing and testing of gypsum specimens reinforced with hemp fabrics, in order to improve some properties of traditional gypsum boards, above all the impact resistance.Two different stacking sequences with both un-impregnated and epoxy impregnated hemp fibres were considered and two different types of fabric, that mainly differ in the weight areal density (380 or 190 g/m2), were used. Three point bending and impact tests at different energy levels were carried out in order to understand how the presence, the relative position of the hemp fabrics within the gypsum matrix and the gypsum-reinforcement interphase affect the mechanical response, so accurate comparisons with the un-reinforced gypsum samples were reported.In the light of the obtained results, the present investigation indicates that hemp fabrics could be used as suitable reinforce in gypsum boards, in order to improve their flexural and impact resistance. Indeed, respect to the unreinforced gypsum the use of hemp reinforcement allowed to reach an improvement of around the 100% and 320% of flexural strength and adsorption energy respectively.

Properties of a new material based on a gypsum matrix incorporating waste brick

Many rehabilitation operations of historic buildings have not succeeded to utilize appropriate material for purpose of the project. Currently, the use of construction waste, especially the waste brick, is largely expanded in the world due to construction and rehabilitation of buildings. For efficient and sustainable use of such material in the rehabilitation of the architectural ornaments, an experimental study was conducted to examine the influence of the waste brick content on the physical and mechanical properties of the gypsum mortar. The materials used to prepare the gypsum mortar were gypsum, natural sand, waste brick, water and superplasticizer. The main variable in this study were the waste brick content (0% to 100%) and the type of the substrate (limestone and brick). The W/B ratio of all the mixtures was kept constant to maintain a similar level of the workability. Several tests were performed to assess the physical and the mechanical behaviour of the gypsum mortars including the adhesion test, XRD and the SEM analysis. The results found show that the adhesion strengths in the mortars are more important when the substrate is made from limestone with the regard to the substrate made with brick. However, excessive percentage of waste brick in the mortar can lead to adverse effects and reduce the adhesive strength. Gypsum mortars made with 75% of waste brick should be recommended for the rehabilitation of the architectural ornaments.

Structure and properties of modified gypsum binder

PurposeThe purpose of the study is regarding the development of eco-oriented technologies for obtaining the building gypsum materials with the involvement of industrial by-products or waste.Design/methodology/approachThe scanning electron microscopy, X-ray microanalysis and IR spectral analysis were used to study the structure of gypsum matrix. The method of comparison of modified and unmodified gypsum matrix was used. Physical modeling of gypsum matrix crystallization is used to study changes in the morphology of hydration products.FindingsThe experimental results show that the addition of technical soot into a gypsum binder leads to a change in the morphology of crystalline hydrates of calcium sulfate dihydrate. Results of the scanning electron microscopy, X-ray microanalysis and IR spectral analysis confirm the change of physical and mechanical characteristics of the gypsum binder due to the structural modification of the gypsum matrix with ultrafine carbon soot. The achieved degree of the structural modification of the gypsum matrix is compatible with the results obtained when the gypsum binder was modified with dispersions of carbon nanotubes.Originality/valueThe morphology of the crystalline hydrates of the gypsum matrix with the addition of 0.04%, 0.06% and 1% of the carbon soot is characterized by the transition of the classical needle-like structure of gypsum dihydrate to the lamellar structure of increased density. One can observe the formation of intergrowths around ultrafine carbon soot particles. The studied carbon additive can improve strength characteristics of the gypsum matrix.

Use of Polycarbonate Waste as Aggregate in Recycled Gypsum Plasters.

The use of gypsum as an indoor coating material for buildings is very extensive. This means that huge amounts of gypsum waste are generated daily worldwide. Therefore, many researchers in the last years have been working on the generation of new gypsum-related materials and products that incorporate recycled gypsum waste as a replacement for the commercial one. On the other hand, trying to reduce the large amounts of plastic generated globally each year, several studies have used different types of plastic waste as aggregates for the development of new construction and building materials. However, up to now, no previous studies have been found in which any type of plastic waste has been used as an aggregate in a recycled gypsum matrix. This paper presents a study in which two different types of waste were mixed for the development of new gypsum plasters: unheated gypsum waste from industrial plasterboard production (GPW) and polycarbonate (PC) waste from rejected compact discs (CDs) and digital versatile discs (DVDs). In this sense, the mechanical and thermal performance of plasters was evaluated. Finally, in order to evaluate the changes in the microstructure of the composites, a scanning electron microscopy (SEM) analysis was conducted. The results showed a good performance of the new composites when both types of waste were combined in the mixes. New lightweight eco-efficient plasters, completely recycled, with enhanced flexural strength (by 14.8%), compressive strength (by 26.8%), and thermal conductivity (42.8% less), compared to the reference material, were achieved.

Gypsum composites with glass granules

The article explored the possibility of reducing the average density of self-reinforced gypsum composites. Gypsum matrix and glass hollow granules leads to the appearance of a synergistic effect. It manifests itself in the formation of a compacted gypsum reinforced matrix, which is filled with microspheres. This provides a modified gypsum stone with high technical indicators. The volume of use of glass hollow granules is increasing every year, including in the construction industry. This material, unique in its properties, provides very high compressive strength, low water absorption, low heat conductivity, high chemical resistance, and radio transparency for its composite materials. The method of obtaining this light filler is a combination of complex physicochemical and hydrodynamic processes that occur during the formation of hollow balls from microparticles of glass melt. Creating effective composites based on glass micro granules as a component in the molding of gypsum products opens up new possibilities for designers and technologists. This will significantly expand their scope.

Combined Effect of Photocatalyst, Superplasticizer, and Glass Fiber on the Photocatalytic Activity and Technical Parameters of Gypsum

In this study, gypsum plasters enriched with the modified photocatalyst TiO2/N and additive components were prepared and analyzed in detail. The aim of this work was to recognize the combined impact of a photocatalyst, polycarboxylic superplasticizer (SP), and glass fiber (F) on the properties of the composed building materials. The mutual compatibility was verified in relation to self-cleaning and air-purifying activity as well as to the technical parameters defined in standards for gypsum materials. The measurements revealed that photocatalytic gypsum material can have high mechanical strength and limited shrinkage as a result of superplasticizer contribution in form of a water-reducing and well-dispersive agent. Normal consistency was achieved by the addition of 0.01 wt % of SP to photocatalytic gypsum mortar or by the addition of 0.2 wt % of SP with a 12% reduction of water. This study also explains why glass fiber fulfills the role of inner reinforcement only if a superplasticizer is simultaneously added to the gypsum matrix. It is possible, by the combined effect of TiO2/N, a polycarboxylic superplasticizer, and glass fiber, to achieve NOx degradation at a high level. Moreover, the significantly improved self-cleaning properties of the complex gypsum plasters surfaces from dye pollutants in comparison to a gypsum plaster with solely a TiO2/N photocatalyst indicate the synergistic effect of the three considered additives.

Reuse of CD and DVD Wastes as Reinforcement in Gypsum Plaster Plates

The continuous and rapid evolution in the field of computing, and in particular in the field of storage devices, has led to the obsolescence of optical discs in favour of mass storage devices. In that sense, a large number of CDs and DVDs become obsolete each day in the world. In trying to create a recovery solution for those pieces, research in which polycarbonate (PC) waste from recycled discs have been used to develop new gypsum coating materials and products has been conducted. In a previous study, the physical and mechanical properties of new gypsum plasters, with PC waste as aggregate, were studied. Following that study, this article aims at creating new gypsum plaster false ceiling plates, using CD and DVD residues in different scenarios: as crushed aggregate in the gypsum matrix, as full reinforcement pieces of the plates and as a combination of both. The mechanical behaviour and the thermal conductivity of the new pieces have been analysed in this paper. The results showed an important improvement in the mechanical and thermal properties of the plates when the PC waste was used in many scenarios.

Mechanical Characterization of Gypsum Composites Containing Inert and Insulation Materials from Construction and Demolition Waste and Further Application as A Gypsum Block

This article analyzes the feasibility of using construction and demolition waste (expanded polystyrene, ceramic, and concrete waste) in a gypsum matrix to manufacture plaster for interior coatings or for prefabricated elements for interior partitions. To do this, several gypsum specimens were prepared (4 × 4 × 16 cm) incorporating different percentages of waste based on the weight of the gypsum (25%, 50%, and 75% of ceramic, concrete, and a mixture of both). Reference samples were also produced (without additions) to compare the results obtained. The compounds with the best performance were selected and lightened by preparing other samples in which 1/3 and 2/3 of the volume of ceramic, concrete, and mixed waste were replaced with expanded polystyrene (EPS). All samples were tested in the laboratory and the following physical and mechanical characteristics were determined: density, surface hardness, flexural strength, compressive strength, capillary water absorption, and thermal conductivity. Several applications were proposed for the selected compounds. A gypsum block with a sandwich configuration was obtained (40 × 20 × 10 cm) using the optimum compound. The block was further tested regarding its density and compression strength. A comparative analysis showed that it is possible to produce materials with a gypsum matrix by adding ceramic, concrete, and EPS waste, improving the behavior of the traditional gypsum and enabling them to be applied in various construction applications. These applications have a lower environmental impact than ordinary ones because they use less primary raw material, due to the reuse of waste.

Radiochemistry of Bangladeshi Phosphogypsum and Leachate Study

Phosphogypsum is a high volume by-product from Phosphate fertilizer factory, named the Triple Superphosphate complex of Bangladesh containing naturally occurring radionuclide. Distribution of 226Ra, 210Pb and 210Po in the fertilizer factory byproduct, phosphogypsum, has been determined using alpha and gamma-spectrometry. Both nuclides (226Ra and 210Po) were found to be concentrated in the finest-grained materials of phosphogypsum. The investigated radionuclide concentration values in PG obtained were comparable with data reported in the phosphogypsum literature, while lower values were found for these radionuclides. Moreover, laboratory radium and polonium leaching experiments of phosphogypsum by deionized water and selective extraction solution have been performed. Radium leaching results showed that fresh phosphogypsum produced the highest concentration of Ra in solution and old phosphogypsum showed a very low transfer to the water. Polonium leaching experiments have shown that only a small amount of polonium is dissolved in filtrated fresh water, this amount is increased when the pH is decreased. It was observed that some extraction solution is more effective at releasing polonium to water from the gypsum matrix. Approximately 32% of 210Po is present on the gypsum surface and not inside the lattice; this position is easily exchangeable with contact of external media (i.e., MgCl2 extraction solution) and 95% of PG was soluble with concentrated cocktail acid solution and a value of 14% 210Po was released with contact of 0.02M sulfuric acid solution. The results obtained in this study can be utilized to verify the environmentally safe use of phosphogypsum as an amendment to agricultural soils.

Compression strength properties of gypsum matrix composites with recovered fibrous scrap materials from post-consumer tyres

Gypsum-based experimental cylindrical samples were prepared using three fractions of recycling tyre 'fluff' material ('as received', fractions >4 mm and <4 mm) in three proportions (10%, 20%, 30%) by weight. The density values of the samples were found to decrease with increasing the proportion of 'fluff' material incorporated in gypsum. Compressive strength and density of cylindrical samples were positively correlated for all combinations, and their relationships were found statistically significant. Compressive strength values ranged between 1.00-7.64 N/mm2 for the 'fluff' fraction <4 mm, where they were the highest, 0.37-1.59 N/mm2 for the 'fluff' fraction >4 mm, where they were the lowest, and between 0.39-4.22 N/mm2 for the 'fluff' fraction 'as received' during recycling, where they were intermediate. Calculations of the required compressive strength in the case of using 'gypsum-fluff' building bricks in interior walls showed that all 'gypsum-fluff' combinations exhibited the adequate strength to perform successfully.

Compression strength properties of gypsum matrix composites with recovered fibrous scrap materials from post-consumer tyres

Gypsum-based experimental cylindrical samples were prepared using three fractions of recycling tyre 'fluff' material ('as received', fractions >4 mm and 4 mm, where they were the lowest, and between 0.39-4.22 N/mm2 for the 'fluff' fraction 'as received' during recycling, where they were intermediate. Calculations of the required compressive strength in the case of using 'gypsum-fluff' building bricks in interior walls showed that all 'gypsum-fluff' combinations exhibited the adequate strength to perform successfully.

Analysis of thermal properties of gypsum materials incorporated with microencapsulated phase change materials based on silica

Microencapsulated phase change materials (MePCMs) were prepared in this study through sol-gel synthesis; these materials consisted of SiO2 as shell and paraffin as core materials, and were subsequently incorporated in gypsum. Further, this study examined the thermal regulation performance of gypsum materials. Fourier transform infrared spectra confirmed the encapsulation of the paraffin with SiO2 shell. Scanning electron microscope (SEM) results showed that the microcapsules obtained at a pH of 2.5 exhibit a regular spherical structure, excellent dispersibility, and compact surface structure. The MePCMs were found to reveal high thermal performance and encapsulation efficiency even in this synthetic condition. This is because the SiO2 shell with its high compactness imparts high thermal stability and a good anti-osmosis performance to the microcapsules. Further, gypsum materials achieved high mechanical strength, compactness, thermal conductivity, and a good thermal regulation performance with the weight ratio of MePCMs at 10 wt%. The results showed that the MePCMs in the gypsum matrix exhibited advantageous application prospects for the thermal regulation in buildings.

Effect of additives SiC on the hydration and the crystallization processes of gypsum

The properties of gypsum materials are largely determined by the structure of the matrix. Additives introduced into the gypsum matrix affect the hydration, size, and morphology of the crystals, the state of the interface and overall porosity. As a result, gypsum binders with increased water resistance and strength are possible to make.This work presents one part of the study of the additives’ influence on hydration and crystal formation processes. The adding of micro and nanoadditives SiC accelerates the hydration and crystallization of gypsum and increases the length of crystals. Dispersed additives act as crystallization centers, and due to the increased specific surface area, they introduce excess energy into the crystallizing system. More significant changes are observed with the joint introduction of micro and nanoadditives and plasticizer. The crystal growth rate along all axes is more balanced, the length and thickness of the crystal increase by 3–5 times, and the crystals grow stronger. The results obtained in the study are useful for understanding the concept of the action of micro and nanoadditives, separately and together with a plasticizer on the processes of crystal formation.

Development of a new eco-friendly composite material based on gypsum reinforced with a mixture of cork fibre and cardboard waste for building thermal insulation

Abstract The aim of this work is to evaluate the thermal and hygrometric characteristics of an eco-friendly composite material made of a mixture of two natural fibres , cork and cardboard waste reinforcing gypsum matrix. For this purpose, mechanical tests, kinetics of moisture adsorption, thermal conductivity and sound propagation speed are carried out. Results show that the composite material formed by fibres is suitable for applications in several structures.

Preparation of microencapsulated phase change materials used graphene oxide to improve thermal stability and its incorporation in gypsum materials

Graphene oxide (GO) was used as emulsifier to prepare the microencapsulated phase change materials (MePCMs) with high thermal stability and impermeability, the chemical structure, particle size distribution, micro-morphology and thermal performance of the microcapsules were investigated by Fourier transform infrared spectrometer (FTIR), laser particle analyzer, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results showed that when GO was used as emulsifier with Span80 and Tween 80, the MePCMs prepared with a higher thermal performance, the particle size are concentrated, the decomposition temperature of the MePCMs are improved, the MePCMs are prepared with a high latent heat with the paraffin content of about 49.9%, the impermeability performance of the MePCMs are obviously improved compared with the samples prepared with other emulsifiers. The gypsum materials that incorporated with different contents of the MePCMs were prepared, the compressive and flexural strength of the gypsum materials are decreased with the increase of the content of the MePCMs, when the content of the MePCMs exceeds 30%, the microcapsules begins to agglomerate in the gypsum, which results in a low compatibility of the MePCMs and gypsum matrix; the incorporation of MePCMs endow the temperature regulation performance of the gypsum building materials, the thermal conductivity of the gypsum materials are decreased as the incorporation of the MePCMs.

Mechanical Properties of a Composite of Gypsum Reinforced with Caroá Fiber and PVAc

The Development of new materials for building industry is a necessary issue to promote sustainability. Gypsum is an important low cost material very abundant in the northeast region of Brazil. Its physical properties make it an interesting material to form composite materials. This work presents a study of gypsum reinforced with Caroá (neoglasiovia variegate) natural fibers, where different amounts of fibers (1, 2, and 3%) were added into gypsum matrix. Three different fiber sizes (5, 10, and 20mm) were used to evaluate the effect of fiber size on the properties. PVAc was added in order to enhance the interactions between matrix and fibers. Mechanical strength was characterized by compression and bending tests. The addition of 1% mass Caroá fibers leads to a slightly increase on the mechanical strength independently of fiber size.

Sound absorption of recycled gypsum matrix composites with residual cellulosic pulp and expanded polystyrene

This work aimed to study the technical feasibility of using industrial gypsum, expanded polystyrene (EPS), and cellulose solid wastes in the production of acoustic insulation panels for buildings. Five traces of acrylic gypsum matrix were produced with variations in the proportions of cellulosic pulp and EPS and always maintaining the same proportion of recycled gypsum and water. The composites produced were tested according to the ISO 10534-2 (2015) standard for the determination of the coefficient of sound absorption and ABNT NBR 14715-2 (2010) for bending tests. The results didn’t show statistically significant differences in the coefficient of sound absorption with variations in the quantities of each material. However, the sonic frequency of the tests directly influenced the results, presenting a better performance at a low frequency (250 Hz). The results qualify the composite produced for use as acoustic insulation and can be used in plates for sound reflection in buildings in places where it doesn’t require resistance to great stresses.

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.