Plaster Mixtures Research Articles

ADHESIVE ABILITY OF GYPSUM-CONTAINING PLASTER COMPOSITIONS

The traditional material for the construction of buildings in the Northern Black Sea region is a cheap local stone ‒ limestone-shell rock. Most of the buildings in the central part of the city of Odesa, which are of historical and architectural value, are constructed of this material. With proper care and maintenance, these structures can perform their functions for hundreds of years, but as a result of shell rock moisture due to negligent operation and a number of other reasons, the supporting structures are damaged, followed by the collapse of the building. In many cases, the direct cause of the destruction of load-bearing walls is the damage or absence of the outer plaster layer. Repairing walls with cement compounds exacerbates the problem. The article discusses some aspects of the possible use of gypsum-based composite materials for repairing damaged walls of limestone-shell rock buildings. The requirements for the repair composition are formulated. The expediency of using gypsum as a binder for the repair plaster mixture for exterior repairs is substantiated. An ash-gypsum-cement composition was used to increase the water resistance of the plaster. Sufficient water resistance and vapor permeability of the proposed composition were confirmed. This paper presents the results of studying the adhesive strength of the contact of the developed composition with the surface of various materials. Methods and measuring equipment developed at the ODABA were used. The adhesion strength of the proposed mixture with the surface of shell rock is close to the standard strength. The use of the adhesive additive Ceresit CC 81 increases the adhesive strength of the joint of the proposed composition with shell rock by 1.5 ‒ 2 times. The optimal amount of the adhesive additive to be introduced will be determined by the results of a multifactorial experiment to study the effect of a complex of chemical additives of different functional purposes on the properties of the proposed repair composition.

Experimental study of the effect of the addition of Posidonia Oceanica fiber on the thermal and acoustic insulation properties of plaster

In this work, plaster and natural Posidonia Oceanica (PO) fibers are combined to create a composite material that was recently produced. This work’s primary objective is to assess the mechanical and thermophysical performance of the composite material in order to determine whether or not it may be used as a thermal and acoustic insulation material in buildings. For this end, prismatic and parallelepipedic specimens of different dimensions were made with fiber percentages ranging from 0% to 20%. In addition, parallelepiped panels (600 mm × 600 mm × 40 mm3) were also prepared containing 10% of PO fibers. Mechanical properties (flexual strength, compressive strength), thermal properties and sound absorption coefficient were investigated. For each test specimen, the density was calculated for a proportion of fibers ranging from 0% to 20%. The results indicated a marked improvement in the compressive and flexural strength of the fiber-reinforced mixtures. This improvement is respectively 14.5% and 33.8% for mixtures containing 10% of PO fibers. Additionally, the addition of PO fibers significantly decreases density (by 40.5%), thermal conductivity (by 68.5%) and thermal diffusivity (by 36.9%) of the different mixtures. The ideal mechanical characteristics are attained when 5%–10% of the volume is made up of Posidonia Oceanica fibers. The results of the sound absorption coefficient test show that the mixture of plaster with 10% fibers has a good sound absorption coefficient of 0.78 for high frequencies between 1000 Hz and 4000 Hz. This work has shown conclusively that the incorporation of PO fibers, up to a maximum of 10% with plaster, makes it possible to obtain a lightweight composite that can potentially be used as a new insulating construction material.

Optimizing the Compositions of Plaster Mixtures Based on Gypsum Binder Using REOLIN RA 120

Optimizing the Compositions of Plaster Mixtures Based on Gypsum Binder Using REOLIN RA 120

INCREASING THE WATER RESISTANCE OF THE PLASTER MIXTURE BASED ON GYPSUM-CONTAINING BINDER

The article considers the prospects of using gypsum-based composite materials for repairing damaged walls of limestone-shell rock buildings. Repairing damaged shell rock structures with cement compositions intensifies destructive processes; the use of lime-sand mixtures for repair work on building facades is problematic due to their prolonged hardening. The article substantiates the use of gypsum as the basis of the repair composition. The use of gypsum composites for exterior works requires a significant increase in their water resistance. A plaster mixture based on an ash-cement binder with an addition of lime is proposed; a series of samples with different component contents were made in the planned experiment. Their water resistance was studied using two criteria: the conventional softening coefficient (Кр) and the new one - the water resistance index (Iw); a comparison of these criteria was performed. The significant dependence of these criteria on the measurement conditions, which are not currently standardized, is established. Mathematical models of water resistance characteristics have been built, with the help of which the influence of the content of components on the resistance of the plaster composition to water has been analyzed. To further improve the water resistance of the mixture, a hydrophobizing additive was selected in terms of surface wetting and water absorption. Further research is aimed at optimizing the repair composition using plasticizing, hydrophobizing, and adhesive additives.

Fuctional balancing in complete dentures- A case report revisiting the paterson’s technique

: A good occlusion is the key to the comfort and longevity of a prosthesis. : This case report presents a 63 year old male patient who reported with the complaint of difficulty in chewing since past 3 months.: On examination, the patient presented with completely edentulous upper and lower arch. A detailed case history was recorded followed by, primary and secondary impressions. The maxillo-mandibular relation was recorded conventionally on wax occlusal rims. A trough was then made in the wax and filled with a mixture of dental plaster and carborundum. The mix was kept 2mm above the plane. The rims were inserted and the patient was instructed to perform lateral and protrusive movements resulting in the incorporation of the compensating curves. The recorded plaster index served as a guide for the teeth arrangement. The denture was processed and delivered with very minimal need for post insertion corrections.: According to Paterson (1923), an articulator with lateral movements is not necessary to establish a balanced occlusion when using the functional technique. The teeth arrangement is entirely dependent on the established curves for obtaining balance.: Various techniques are cited throughout the literature to provide a successful prosthesis. With all the advances in the digital era, denture fabrication is not an automated procedure. It is pertinent that the clinicians master the fundamentals of prosthesis fabrication, without which any amount of technology and/or persistence might be in vain.

Dentinal Microcracks after Root Canal Preparation in Primary Root: An In Vitro Evaluation of ProTaper Gold and Kedo-S Rotary File Systems.

There is a possibility of dentinal crack formation in primary teeth after root canal preparation using rotary files. To evaluate and compare the effect of ProTaper-Gold and Kedo-S rotary files on crack formation after root canal preparation in primary molars. A total of 120 freshly extracted mandibular primary molars (6-9 years) were randomly divided into three groups of 40 each: ProTaper-Gold, Kedo-S, and Hand H-files, respectively. The roots were covered with a snuggly fitting surgical glove and stabilized in the teeth slot of a silicone mold of mandibular mixed dentition. Dental casts were obtained in a mixture of plaster of paris and sawdust. A screw system was incorporated in the cast for stabilization of the cast into the phantom head. All the root canals were instrumented in a standard operating position till 1 mm short of the radiographic apex. All roots were then stained and sectioned perpendicular to the long axis at the furcation level and 2 mm below the furcation to obtain one section per tooth. Sections were examined under a stereomicroscope at 25× magnification for any crack formations and recorded. Data were analyzed using Wilcoxon signed-rank and Kruskal-Wallis tests (p = 0.05). The total number of cracks in terms of percentage following the use of ProTaper Gold, Kedo-S, and H-files were 35, 10, and 0%, respectively, on the upper surface and 15, 5, and 0% on the lower surface. Within the group, there was a statistically significant difference in ProTaper-Gold (p = 0.001). The use of ProTaper-Gold resulted in a greater number of dentinal cracks compared to Kedo-S and H-files. Patil MB, Mandroli PS, Jalannavar P, et al. Dentinal Microcracks after Root Canal Preparation in Primary Root: An In Vitro Evaluation of ProTaper Gold and Kedo-S Rotary File Systems. Int J Clin Pediatr Dent 2023;16(5):692-697.

RESTORATION COMPOUNDS FOR TERRAZZITE PLASTER ON THE EXAMPLE OF CULTURAL HERITAGE SITES OF THE 20TH CENTURY (RUSSIA)

Inroduction: Gradual destruction of buildings or structures of historical significance is a natural process that cannot be stopped. Therefore, preservation of architectural monuments is one of the most important areas of restoration activity. Complete replacement of damaged building materials of architectural monuments changes the historical appearance, and thus cultural sites are stripped of their original look. Innovations in the re-creation of historical building materials and technologies help preserve historical continuity. The purpose of the study was to develop a number of compounds of terrazzite plaster mixtures for cultural heritage sites of the 20th century, which, from an aesthetic point of view, will not allow the loss of the natural and picturesque appearance of the monument, and will be able to preserve the “patina of time”. As a result of the research, the authors studied the compositions of the selected samples, proposed restoration compounds of terrazzite plaster, and determined the algorithm for applying an analogue of the historical plaster. In terms of technical and economic indicators, the developed restoration compounds are effective and make it possible to return architectural monuments to their original appearance with minimal costs. Based on the results obtained, conclusions were drawn about the feasibility of using the proposed new components in terrazzite plaster mixtures to increase strength and ensure high-quality adhesion of the old and new plaster layers. The proposed technology contributes to the return of architectural monuments to their original appearance without losing the historical authenticity of the buildings.

Low-temperature synthesis of binder with belite content

Sol-gel methods or hydrothermal treatment in combination with low-temperature burning are used for low-temperature syntheses of hydraulically active dicalcium silicate. The paper describes a two-stage preparation process without the use of an autoclave. In the first phase, the precursors of hydraulically active phases are prepared. In the second phase, burning up to 1000 °C takes place to form a C2S-based binder. Unlike commonly used procedures of the sol-gel method, solid raw materials and water are used. The main raw materials are quicklime and a source of SiO2 and then various activators. X-ray diffraction analysis and electron microscopy methods were used for the research. The resulting binders are similar to hydraulic lime, they achieve low initial strengths, the long-term strengths are satisfactory. It is suitable for the preparation of mortars and plaster mixtures.

Rancang Bangun Mesin Pengayak Pasir Sistem Rotary Dengan Tiga Grade Hasil Ayakan

Sand is the main ingredient in the construction process, so based on its function, size separation is needed. This size separation is done by sifting sand. Based on the survey, many construction or industrial workers use traditional methods of sifting sand, and the results obtained are less effective in terms of capacity and working time.The rotary system sand sieving machine is planned as a tool to make it easier to sift sand. The sifter tube is designed with 2 sieves. The first filter uses a mesh size 6 and the second filter uses a mesh size 8. This is done to produce 3 grades of sand.This rotary system sand sifter machine aims to sift sand with 3 different sieve results, namely fine sand, medium sand, and gravel. Fine sand is used as a mixture of plaster for concrete walls, medium sand is used as a mixture in bricklaying, and gravel is used as a mixture of foundation casts. In the mechanical movement system using a 1 Hp AC motor as a source of rotation, then the rotation of the motor is transmitted through a reducer with a ratio of 1:40 and then forwarded to the shaft. On the shaft there is a filter for sifting the rotary system sand.This research was conducted with 3 variations of the angle of the sieve which is 10°, 15°, 20°. In testing the maximum capacity in one test is 30 kilograms. The best sieve results were obtained from testing with a 10° sieve angle using dry river sand and dry land sand.

Physical-mechanical properties of new recycled materials with additions of padel-tennis ball waste

Around 320 million new padel and tennis balls are used worldwide each year, the game of padel also being known as padel or padel tennis. This level of use of padel-tennis balls is estimated to produce approximately 21,000 metric tons of waste from the balls, which are manufactured with a vulcanized natural rubber core covered with felt. Considering how plaster has been one of the most widely used materials in the construction sector, with excellent aesthetic and mechanical properties for indoor use, this research aims to assess the physical and mechanical properties of new recycled materials with the addition of padel-tennis waste. Several plaster mixtures were made using different residues from balls (felt and rubber), previously crushed, according to different ratios of water to gypsum and percentages. The statistical analysis indicates the representativeness and robustness of the results with a very high adjustment of the calculated models (coefficients of determination R2 greater than 98%). Also, it corroborates that density is a determining factor in the mechanical properties of plasters for the three types of residues studied and it is a key parameter in the design of those construction elements that require lightness properties. The results confirmed that the new recycled material complies with the minimum requirements established under the UNE-13279 building standard, and even the flexural strength increases by up to 20% when felt waste is used. Mechanical properties (flexure and compressive) increase more intensely when the surface hardness exceeds the value of 60 units. The water absorption and surface hardness also meet the standards, so the innovative material would be suitable for the manufacture of pre-cast panels, such as suspended ceiling plates or interior cladding walls, as well as any other construction element that is currently made from gypsum, thus optimising sustainability and the circular economy in the construction sector. The new innovative material includes the benefits of secondary raw materials and the problem of padel-tennis waste disposal.

Experimental investigation of the mechanical properties and large-volume laboratory test of a novel filling material in mining engineering

In this paper, a novel filling material was developed that consisted of a coal gangue and fly ash mixture as the main material and a ground slag, quicklime and plaster mixture as the cementing material. Moreover, an auxiliary agent was added as an activator. The test results showed that the optimum composition of the filling material included coal gangue and fly ash at a 2:1 ratio, accounting for 85% of the total mass, ground slag (G), quicklime (Q) and plaster (P) at a 5:3:2 ratio, accounting for 15% of the total mass, an expansive agent content of 0.01%, and a modifier additive content of 1.0%. A large-volume sample (1 m × 1 m × 1 m) was evaulated with this optimized material composition. The experimental temperature, mechanical performance, regeneration strength, and failure characteristics were determined. The results showed that the temperature of the middle part of the filling body was the highest and peaked at 40.2 °C. The filling material had a high compressive strength and exhibited ideal plastic deformation characteristics. The strength could be restored after damage had occurred and the fracture surface was destroyed along a certain angle.

Plaster and magnets: Modelling magnetic fabric development in magma intrusions using scaled analogue experiments

Understanding magma behaviour during emplacement within the crust is vital for understanding the dynamic processes occurring in volcanic systems. However, linking the static record of magma flow to its dynamic origin is challenging, particularly as macroscopic indicators of magma flow are often not observed, absent and/or have been modified after emplacement. Anisotropy of magnetic susceptibility (AMS) has been used as an important tool in field studies to infer magma flow direction, using the magnetic fabric as a record of the magma intrusion dynamics and to identify magma source regions. Here, we describe a new method to explore magnetic fabric development in magma intrusions and lava flows using scaled analogue laboratory experiments. Coloured mixtures of Plaster of Paris (the magma analogue) seeded with magnetite particles were loaded concentrically into a piston and injected through a central port in the base of a box filled with compacted fine-grained wheat flour (the crust analogue). This created a series of interconnected sheet and tube-like ‘magma’ intrusions which eventually breached the surface to feed a model ‘lava flow’. Once solidified, the intrusions were excavated and sampled for AMS, with the results showing that magnetic fabrics were preserved. A new dynamic scaling analysis shows the plaster mixture represents the intrusion of dacite magma into the shallow crust. These models provide proof-of-concept that this new methodology and scaling analysis can be used to explore AMS development in viscous (dacite) magma intrusions in nature, with the potential for direct comparison with field-based indicators of magma flow dynamics.

Properties Evaluation of Composite Materials Based on Gypsum Plaster and Posidonia Oceanica Fibers

Estimating the amount of material without significant losses at the end of hybrid casting is a problem addressed in this study. To minimize manufacturing costs and improve the accuracy of results, a correction factor (CF) was used in the formula to estimate the volume percent of the material in order to reduce material losses during the sample manufacturing stage, allowing for greater confidence between the approved blending plan and the results obtained. In this context, three material mixing schemes of different sizes and shapes (gypsum plaster, sand (0/2), gravel (2/4), and Posidonia oceanica fibers (PO)) were created to verify the efficiency of CF and more precisely study the physico-mechanical effects on the samples. The results show that the use of a CF can reduce mixing loss to almost 0%. The optimal compressive strength of the sample (S1B) with the lowest mixing loss was 7.50 MPa. Under optimal conditions, the addition of PO improves mix volume percent correction (negligible), flexural strength (5.45%), density (18%), and porosity (3.70%) compared with S1B. On the other hand, the addition of PO thermo-chemical treatment by NaOH increases the compressive strength (3.97%) compared with PO due to the removal of impurities on the fiber surface, as shown by scanning electron microscopy. We then determined the optimal mixture ratio (PO divided by a mixture of plaster, sand, and gravel), which equals 0.0321 because Tunisian gypsum contains small amounts of bassanite and calcite, as shown by the X-ray diffraction results.

Критерии эффективности при проектировании составов сухих санирующих смесей

The article considers the principles for designing the compositions of sanitizing plaster mixtures, which allow forming the required structure and properties of the material. Based on experiments carried out by the planning method, it has been found that the key parameters that determine the effectiveness of sanitizing properties are surface absorbency and capillary absorption. A method for direct evaluation of the functional effectiveness of sanitizing compositions is proposed.

Fabrication of 3D printed head phantom using plaster mixed with polylactic acid powder for patient-specific QA in intensity-modulated radiotherapy

This study aimed to fabricate a heterogeneous phantom replicating the commercial Rando phantom by mixing plaster powder and polylactic acid (PLA) powder. Producing a heterogeneous phantom using Plaster and PLA is cheaper because it can be easily obtained in the commercial market. Additionally, patient-specific Quality Assurance can be easily performed because the phantom can be produced based on the patient’s CT image. PLA has been well studied in the field of radiation therapy and was found to be safe and effective. To match the mean Hounsfield unit (HU) values of the Rando phantom, the bone tissue was changed using plaster and 0–35% PLA powder until an appropriate HU value was obtained, and soft tissue was changed using the PLA infill value until an appropriate HU value was obtained. Bone tissue (200 HU or higher), soft issue (− 500 to 200 HU), and air cavity (less than − 500 HU) were modeled based on the HU values on the computed tomography (CT) image. The bone tissue was modeled as a cavity, and after three-dimensional (3D) printing, a solution containing a mixture of plaster and PLA powder was poured. To evaluate the bone implementation of the phantom obtained by the mixture of plaster and PLA powder, the HU profile of the CT images of the 3D-printed phantom using only PLA and the Rando phantom printed using only PLA was evaluated. The mean HU value for soft tissue in the Rando phantom (− 22.5 HU) showed the greatest similarity to the result obtained with an infill value of 82% (− 20 HU). The mean HU value for bone tissue (669 HU) showed the greatest similarity to the value obtained with 15% PLA powder (680 HU). Thus, for the phantom composed of plaster mixed with PLA powder, soft tissue was fabricated using a 3D printer with an infill value of 82%, and bone tissue was fabricated with a mixture containing 15% PLA powder. In the HU profile, this phantom showed a mean difference of 61 HU for soft tissue and 109 HU for bone tissue in comparison with the Rando phantom. The ratio of PLA powder and plaster can be adjusted to achieve an HU value similar to bone tissue. A simple combination of PLA powder and plaster enabled the creation of a custom phantom that showed similarities to the Rando phantom in both soft tissue and bone tissue.

Experimental Investigation of a New Design of Insulation Gypsum Plaster Blocks

Green building materials are an alternative to ordinary materialsoffering multiple environmental benefits. This study consists of an experimental investigation of a new design of gypsum plaster blocks. First, a mix design of gypsum plaster and water mixture was prepared. The optimal mix composition was determined according to the mechanical and physical properties, such as the water absorption, the temperature of hydration, the density, and the compressive strength of different gypsum plaster and water mixtures made by varying the water dosage. The second part of this investigation aims to study a new design of green blocks prepared from the optimal water and gypsum plaster mixture. The new blocks are perforated to lighten them and to reduce their thermal conductivity in order to make them moreinsulate. Experimental tests were conducted on the block prototype, such as the measurement of dimensional tolerances, compressive strength, density, flatness, water absorption, residual moisture, surface hardness, and thermal conductivity. Experimental test results show that the new blocks have very low density, and their compressive strength is sufficient for wall construction. In addition, the manufacturing process of the new blocks is very easy and very fast. Finally, the obtained physical and mechanical properties of the new gypsum plaster blocks give it the opportunity to be used for interior walls for building constructions.

The Effect of Gamma Value Alterations for Detecting Vertical Root Fracture in Indirect Digital Radiograph (an In-vitro Study)

Background and Objectives Most digital imaging systems offer a variety of image processing techniques. Due to the importance of the accuracy of these images and their widespread application, this study aims to evaluate the detection of vertical root fracture (VRF) in indirect digital images by changing their gamma values. Subjects and Methods In this study, 23 extracted teeth were prepared as samples from dental clinics in Ahvaz, Iran. The radiographs were obtained from the samples before and after VRF induction. After root canal preparation, a very thin disc was used to divide the teeth into two halves in the buccal-lingual direction to create a VRF. The two halves were re-attached to each other and mounted in in molds filled with a mixture of plaster and sawdust. After processing the images by adjusting their gamma values using low, medium and high settings, the images were viewed by two radiologists for the presence or absence of VRF. Results In all three modes of gamma adjustment, the sensitivity, specificity and overall accuracy of images were high and there was no significant difference between the three modes. Conclusion The high gamma for digital images can used to as a filter to detect VRF. The images with medium and low gamma values are less helpful for detecting VRF

Evaluating the individual, dual usage of (TGP) and (SF) additives on improving gypsum characteristics

The purpose of this study is to determine the impact of adding Tree Glue Powder (TGP) and Silica Fume (SF) powders (by weight) alone and in combination on the characteristics of gypsum plaster. The study will focus on two critical gypsum properties: compressive strength and setting time. According to the study plan, a total of twelve specimens will be utilized. The twelve specimens were divided into four groups according to their TGP and SF contents (by weight), which were (0.0 percent), (1.0 percent) for (TGP) and (0.0 percent), (1.2 percent) for (SF) respectively. Three cubic (5 × 5 × 5 cm.) specimens were used to determine the average outcome for each blend. The ratio of water to gypsum plaster (W/P) was set at (0.5) for various mixtures. It was discovered that by adding just (SF) to Gypsum plaster mixtures, compressive strength is increased while setting time is decreased. On the other hand, adding merely (TGP) to the mixtures reduces compressive strength while significantly increasing setting time. Additionally, it was discovered that when both additives (SF) and (TGP) were used, two benefits were acquired, namely an increase in compressive strength and a minor increase in setting time(as compared to the no additives reference case).

Effect of Chopped Carbon Fibre (CCF) on enhancing the compressive strength and density of gypsum plaster

A present study investigates the influence of employing Chopped Carbon Fibre (CCF) on the characteristics of gypsum plaster (compressive strength and Density). The study plan consists of four gypsum plaster mixtures; these mixtures are classified into two categories based on their (Water/Gypsum Plaster) ratios (0.6 & 0.7). Every set subdivided by two categories based on 0.0 and 0.3 percent of CCF volume fraction (Vf). For each admixture, three samples (50 * 50 * 50) mm adopted. It was discovered that utilaized CCF to gypsum plaster mixes enhance and improve density and compressive strength for two W/GP ratios. The rate of improving compressive strength when use CCF increase by rising ratio of W/GP. furthermore, increasing the (W/GP) ratio results in a drop compressive strength and density for Volume ratios; while the CCF behavior may reduce drop rate of compressive strength and density.

Reuse of waste tire textile fibers from tires in plaster mixtures

The waste tire textile fibers from tires are generated as a by-product and are classified as special waste. To avoid landfilling and incineration of this waste, it is necessary to focus on its further use. This article describes an experimental study of the use of waste tire textile fibers for plaster mixtures. Waste fibers were added in different amounts of 2.9%, 3.6%, and 4.3% related to the weight of cement, the effect of fibers on selected properties was monitored. The results of the experimental work show that the lower addition of waste fibers (2.9% and 3.6%) had a predominantly positive effect on mechanical properties. By exceeding of the optimal dose of fibers, the tested properties of the plasters got worse.