Plaster Composites Research Articles

Thermal regulating performance of gypsum/(C18–C24) composite phase change material (CPCM) for building energy storage applications

A new type of organic/inorganic form-stable composite phase change material (FSCPCM) was prepared via direct impregnation of eutectic mixture of octadecane (C18) and tetracosane (C24) into gypsum. The maximum mass percentage of C18–C24 absorbed in gypsum was determined as 18% without the leakage of C18–C24 in liquid state. The Fourier Transform Infrared (FT-IR) spectroscopy and Differential Scanning Calorimetry (DSC) techniques were used to characterize the FSCPCM. The FT-IR spectra confirmed that any chemical interaction did not occur among the components of the composite during the impregnation. Besides, DSC analysis showed that the FSCPCM had reversible melting and freezing behavior and quite satisfying thermal properties for building applications. The composite maintained its chemical structure and thermal energy storage characteristics after 1000 melting/freezing cycles. In addition, the gypsum plaster with FSCPCM exhibited excellent thermal regulating performance when compared to that of only gypsum plaster under the same conditions. From all results, it can be deduced that the obtained gypsum based composite plaster is a promising material to control room temperature and to conserve energy in buildings.

Laboratory Verification of Water Vapour Permeability of Plaster Compositions

There are many significant historic buildings of our national heritage in the Czech Republic that worth protecting. These astonishing buildings are most frequently damaged by water, precisely speaking by moisture. The moisture can come from several sources, for example from a flood. That is the reason we should know about the materials and their behaviour from the point of view of the moisture in the vapour form as much as possible. This paper summarizes properties important for material water vapour permeability represented by water vapour resistance factor. There are stated and tested three compositions of materials, commonly used in the praxis, in the paper. The compositions are: basic adhesive diffusion mortar with no finishing; basic adhesive diffusion mortar + silica penetration; basic adhesive diffusion mortar + silica penetration + silicate plaster. Not only diffusion parameters but also the border condition and their impact on the material behaviour have been tested and determined. We should know how to treat these buildings during a flood well. After previous floods that damaged many valuable buildings it seems to be a very priceless familiarity. Moreover the tested values help to find out if there is going to be condensation of water vapour on the surface of the tested material inside a building.

A Double-Sided In-Plane Lateral Comb-Drive Actuator Fabricated by a Plaster-Based 3D-Printer

In this paper, design, fabrication and characterization of a double-sided in-plane lateral comb-drive actuator fabricated by a plaster-based 3D-printer is described. The design is based on MEMS (Micro Electro-mechanical Systems) design concept. The movable part of the actuator consists of a (10x52.5) mm rectangular plate, and the end sides have depression areas in order to fit a (0.5x21.3) mm beam-shaped hinges. In the remaining sides of the plate, 18 comb fingers (0.5x10) mm are set at each opposite side. The stationary part of the actuator consists of 17 comb fingers with the same dimension to that of the stationary ones, and they are set at both sides of a frame and interdigitated with the movable comb fingers on the same plane. The gap between the movable and stationary comb fingers is 1.0mm. The structure thickness is 1.5mm. Such a structure, which both sides are provided with an in-plane interdigitated comb fingers, is called double-sided in-plane lateral comb-drive actuator. This actuator has been fabricated by using a plaster-based 3D-printer. Since plaster composite is an electrical insulating material, the structure has been suitably masked and the upper and lateral surfaces have been metallized thereafter by Au ion sputtering for the actuator electrodes formation. The hybrid fusion of 3D-printing manufacturing technology and MEMS-based design concept has been recently proposed by the authors and named as SMEMS (Sub-milli Electro-mechanical Systems), since the smallest possible fabrication size is in the order of sub-millimeters. The advantage of SMEMS technology is the quick and easy fabrication of 3D structures from 3D-CAD data. Furthermore, SMEMS is completely environment-clean since any hazardous chemicals or gases are used. The actuator has been driven by differential voltages, where both sides are biased at a voltage of 100V, and a 200 Vpp and its 180°shifted sinusoidal voltages are applied at each side. The actuator laterally moved by 96.8μm (full width) at a resonance frequency of 72Hz, and the mechanical quality factor has been estimated to be about 10.

High-resolution geomatic and geophysical techniques integrated with chemical analyses for the characterization of a Roman wall

Abstract The aim of this work is the characterization of an ancient Roman wall through high-resolution geomatic and geophysical methods. Chemical analyses were performed in order to better identify the constitutive material. The archaeological wall of pre-Trajan age, discovered in 2011, is decorated with mosaics and located in a subterranean gallery below the Trajan's Baths on the Oppian hill (Rome historical centre). The dataset was collected using a 3D high-resolution laser scanner for the reconstruction and analysis of the skin wall, a Ground Penetrating Radar (GPR) to investigate the inner core of the wall and chemical analyses to characterize the composition of plaster and mosaics. The joint interpretation of data collected with different methodologies demonstrates the capability of the proposed method to characterize the wall in terms of constructive materials and to detect fractures and discontinuities between materials. A classification of the intensity parameter was performed starting with a visual analysis of the textured model built from laser scanner data before comparing it with the georadar results and the chemical analyses of the constitutive elements of the wall. Fractures and discontinuities partially visible on the surface of the structure and present in the inner part were mapped combining laser scanner and georadar data. The obtained results show that the integrated interpretation of the proposed techniques can provide important information about composition, geometry of the wall, correlation between physical and mechanical parameters and an extensive mapping of fractures and anomalies embedded within the wall.

Application of Polymer Plaster Composites in Additive Manufacturing of High-Strength Components

Today, 3D-printing with polymer plaster composites is a common method in Additive Manufacturing. This technique has proven to be especially suitable for the production of presentation models, due to the low cost of materials and the possibility to produce color-models. But nowadays it requires refinishing through the manual application of a layer of resin. However, the strength of these printed components is very limited, as the applied resin only penetrates a thin edge layer on the surface. This paper develops a new infiltration technique that allows for a significant increase in the strength of the 3D-printed component. For this process, the components are first dehydrated in a controlled two-tier procedure, before they are then penetrated with high-strength resin. The infiltrate used in this process differs significantly from materials traditionally used for infiltration. The result is an almost complete penetration of the components with high-strength infiltrate. As the whole process is computer-integrated, the results are also easier to reproduce, compared to manual infiltration. On the basis of extensive material testing with different testing specimen and testing methods, it can be demonstrated that a significant increase in strength and hardness can be achieved. Finally, this paper also considers the cost and energy consumption of this new infiltration method. As a result of this new technology, the scope of applicability of 3D-printing can be extended to cases that require significantly more strength, like the production of tools for the shaping of metals or used for the molding of plastics. Furthermore, both the process itself and the parameters used are monitored and can be optimized to individual requirements and different fields of application.

The adhesive bonding with buckypaper–carbon nanotube/epoxy composite adhesives cured by Joule heating

Detrimental positive feedback effect due to the semi-conductive nature of carbon nanotube (CNT) was found in Joule heating of CNT/epoxy composite adhesives. In this work a process was developed to overcome the positive feedback effect by using a buckypaper–CNT/epoxy composite plaster patch. With this process, not only the positive feedback effect can be avoided but also more uniform curing of the CNT/epoxy adhesive can be obtained with a beneficial negative feedback effect. This process requires only simple equipment and is theoretically the most time and energy saving process for curing epoxy adhesive. The addition of CNTs in the epoxy can provide better heat transfer and strengthening of the epoxy adhesive. With the use of buckypaper/0.5% CNT/epoxy adhesive cured by Joule heating, the bonding strength increased significantly to be 67% higher compared to conventionally cured specimen with pure epoxy.

Seismic improvement of infilled nonductile RC frames with external mesh reinforcement and plaster composite

The objective of this paper is to report the result of an experimental program conducted on the strengthening of nonductile RC frames by using external mesh reinforcement and plaster application. The main objective was to test an alternative strengthening technique for reinforced concrete buildings, which could be applied with minimum disturbance to the occupants. Generic specimen is two floors and one bay RC frame in 1/2 scales. The basic aim of tested strengthening techniques is to upgrade strength, ductility and stiffness of the member and/or the structural system. Six specimens, two of which were reference specimens and the remaining four of which had deficient steel detailing and poor concrete quality were strengthened and tested in an experimental program under cyclic loading. The parameters of the experimental study are mesh reinforcement ratio and plaster thickness of the infilled wall. The effects of the mesh reinforced plaster application for strengthening on behavior, strength, stiffness, failure mode and ductility of the specimens were investigated. Premature and unexpected failure mode has been observed at first and second specimens failed due to inadequate plaster thickness. Also third strengthened specimen failed due to inadequate lap splice of the external mesh reinforcement. The last modified specimen behaved satisfactorily with higher ultimate load carrying capacity. Externally reinforced infill wall composites improve seismic behavior by increasing lateral strength, lateral stiffness, and energy dissipation capacity of reinforced concrete buildings, and limit both structural and nonstructural damages caused by earthquakes.

Thermal properties of smart microencapsulated paraffin/plaster composites for the thermal regulation of buildings

Smart plaster composites were manufactured by mixing plaster with different amounts of Micronal® DS5001X microcapsules containing a paraffin mixture with a melting point of 26°C to develop new construction materials with high thermal energy storage capacity for use in high-comfort constructive systems. Thermal characterization of smart plaster composites was performed using two different experimental techniques: thermal energy storage properties, such as latent heat and heat capacities, were investigated using a Transient Guarded Hot Plate Technique (TGHPT), whereas thermal conductivities and diffusivities were measured using a periodic temperature method. The results revealed an improvement in the latent heat and the heat capacities of the composites with increasing paraffin content in the composite. Furthermore, thermal conductivities and diffusivities decreased with increasing microencapsulated paraffin concentration.

USING NANOFIBERS IN THE RESTORATION OF HISTORIC COATINGS – RESISTANCE TO SALT CRYSTALLIZATION

The paper presents partial results of research into the application of nanofibers in the stabilization, conservation, and strengthening of historic plasters. Nanotechnologies applied in all basic technical disciplines currently belong to the most popular fields of research. The restoration of historic and cultural heritage buildings must not in any way damage the preserved original coatings. The execution method and the choice of the suitability of used materials must respect the preserved condition based on the original plaster composition. The research addresses the above issues by applying nanofibers to textile carrier fabrics. The suitability of selected electrospun polymers and acrylates for the purposes of strengthening surface layers, and the application methods of nanotextiles on plasters, were investigated. The objective of this study is to verify whether the newly-designed methodology for the stabilization, conservation, and strengthening of historic plasters meets structural and technical demands, as well as the strict criteria set by cultural heritage conservation.

Influence of PCM Admixture on Thermal Behavior of Composite Plaster

Experimental investigation of the effect of phase change material (PCM) admixture on thermal properties of composite plaster is researched in the paper. Due to its latent heat storage, the applied PCM represents promising way for reduction of buildings energy consumption spent for heating and air conditioning. The investigated composite material is based on commercial dry plaster mixture modified by microencapsulated PCM admixture Micronal DS 5038 produced BASF. The particle size distribution of PCM admixture, original dry plaster mixture, and particular dry mixture with PCM addition are measured on laser diffraction principle. For characterization of the developed materials, measurement of their basic physical properties is done. Specific attention is paid to thermal properties of research materials, whereas the heat transport parameters are measured using transient impulse device, and the DSC (difference scanning calorimetry) analysis is applied for determination of temperatures of phase transitions, enthalpy of fusion and crystallization, and temperature dependent specific heat capacity. The obtained results show significant improvement of the heat storage capacity of PCM modified plasters in dependence on temperature, what can be beneficially used for regulation of the indoor climate.

Plaster Pigments in Traditional Folk Architecture - A Case Study from Moravia (Czech Republic)

The results of analyses of coloured plasters are given in the paper. The samples come from traditional folk earth houses from SE and Central Moravia and were chosen so as all of the most common colours of the Central European folk architecture are present among them: red, yellow, blue, green, and black. The analyses were conducted by the means of light microscopy, which is also a powerful tool for stratigraphical analyses, X-ray diffractometry, Raman spectrometry, end electron microanalysis. Hematite of industrial origin was identified as the red pigment, the yellow one was formed by yellow earth, which also may be a precursor for traditional production of red dye. The widest used blue pigment was ultramarine in the 19th and the first half of 20th century in Moravia. The analysed green pigments were formed by an organic dye of green earth and the black one consisted of soot. Based on the sort and composition of pigment and plaster, the age of the material is also discussed.

Effect of some waste additives on the physical and mechanical properties of gypsum plaster composites

Gypsum plaster composites were synthesized by blending plaster with 0.2–10% of unburnt rice husk, blast furnace slag, calcium carbonate or commercial poly vinyl alcohol polymer (PVA). The normal consistency (NC) and setting time (ST) in addition to apparent porosity (AP), bulk density (BD) and compressive strength (CS) of the composites were determined after 7 and 28days. Results indicated that rice husk, polymer and calcium carbonate increased while slag decreased NC. All additives delayed the setting time, increased the AP and decreased BD of their corresponding composites. The effect of their addition is exaggerated with increased added ratios of either of them. Their compressive strength, on the other hand, increased with slight addition of either of them then it decreased by further increased additions. Physicomechanical properties elucidated that the added wastes exist in the interstitial pores and spaces of the plaster matrix in the composites without any sign of interaction between either of them and set plaster. The formed composites although did not much improve their mechanical properties yet they consume in their formation either cheap available materials or some wastes. The synthesized plaster composites help to clean environment and can be used for low-economical cheap lightweight units suitable for load bearing non-concrete low-height walls of buildings.

IMPACT OF GRANULES FROM CRUSHED EXPANDED POLYSTYRENE PACKAGE ON PROPERTIES OF THERMO-INSULATING PLASTER

The paper deals with the use of lightweight porous aggregate, i.e. crushed expanded polystyrene package crumbs (EPSC) in the composition of thermo-insulating plaster. Its effectiveness is compared to that of spherical granules of expanded polystyrene – white coloured (EPS) and grey coloured (NEOPOR). The content of lightweight aggregate changed from 1.25 to 1.75 l/kg of dry mix. The investigation focused on properties of modified plaster, such as density, compressive strength, thermal conductivity and water vapour permeability. It was established that EPSC reduce density of plaster from 1350 to 530 kg/m3, improving such properties as thermal conductivity and water vapour permeability but decreasing compressive strength. In addition, the paper established the adhesion force of plaster (content of lightweight aggregate was 1.25 l/kg of dry mix) to ceramics, silicate and autoclaved aerated concrete masonry elements. The character of macrostructure of plaster was considered, as well as bonding with a coat of decorative paint. It was found that plaster with EPSC has similar properties to plasters with EPS and NEOPOR aggregates; however, in case of EPSC, the relative vapour resistance is better. The provided regression equations can be used for prediction of differently modified plasters.

A comparative study of wall painting materials and techniques used in fifteenth century Austria by Frederich of Villach and his followers

One of the most important artistic circles in the first half of the fifteenth-century in Austria was the so-called ‘Older Villach's workshop’, founded by Frederic of Villach, a painter who was considered a master of fresco technique. A technical study was made of a number of wall painting cycles by the workshop of Frederic of Villach, first, to gain a broader knowledge of the painting techniques employed, and second, to allow comparison with a further group of wall paintings in Slovenia, which are stylistically related to this workshop and have been studied previously. Of special interest were artworks attributed to Frederic's son Johannes of Ljubljana and a number of other anonymous painters that show important similarities to Frederic's works. Samples of plasters and pigments were analysed by optical microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. An important difference in the composition of plasters was discovered between the selected artistic groups. The palette used comprised predominantly earth and other mineral pigments. The construction of the paintings from incisions and preparatory drawings to the final modelling is basically similar and shows workshop connections. The principal painting technique was a fresco. The results contribute to a wider knowledge concerning the materials and techniques employed in gothic wall paintings in the Alpine region and offer new information that can be used to inform the future conservation of these selected wall paintings.

Exothermic properties of plaster–synthetic composite casts

PurposePlaster casts can cause burns. Synthetic casts do not. Composite plaster–synthetic casts have not been thoroughly evaluated. This study analyzed the temperature from plaster casts compared with composite casts in a variety of in vitro conditions that would simulate clinical practice.MethodsA Pyrex cylinder filled with constant body temperature circulating water simulated a human extremity. Circumferential casts, of either plaster or composite construction (plaster inner layer with outer synthetic layer), were applied to the model. Peak temperatures generated by the exothermic reactions were studied relative to the following variables: dip water temperature (24 °C versus 40 °C), cast thickness (16, 30, and 34 ply), and delayed (5-min) versus immediate application of the synthetic outer layers. Peak temperatures from the all-plaster casts were compared with the composite casts of the same thickness. Finally, the relative cast strength was determined.ResultsPotentially dangerous high temperatures were measured only when 40 °C dip water was used or when thick (30- or 34-ply) casts were made. Cast strength increased with increasing cast thickness. However, the presence of synthetics in the composite casts layers did not increase cast strength in every case.ConclusionWhen applying composite casts, the outer synthetic layers should be applied several minutes after the plaster to minimize temperature rise. Composite casts do not routinely generate peak temperatures higher than plaster casts of similar thickness. Because the skin of children and the elderly is more temperature-sensitive than average adult skin, extra care should be taken to limit the exothermic reaction when casting children and the elderly: clean, room temperature dip water, minimal required cast thickness, avoidance of insulating pillows/blankets while the cast is drying.

Plasters in mediaeval mural paintings of Carinthia and their influence on Slovenia

The purpose of the present study was analysis of plasters used as supports for mural paintings carried out by what was known as ‘Older Villach's workshop’ and its followers, active in the first half of the fifteenth century in Carinthia (Southern Austria) and Slovenia. The composition of plasters, the number of layers, the application of giornatas and a possible use of lime-wash was of interest, as was the comparison of results obtained, in order to establish a possible technical characterization and connection among the selected wall cycles that show an important stylistic relationship. Small samples were analysed by OM, SEM-EDX and XRD. The results revealed significant differences in the composition of plasters that can roughly divide the murals into two groups. The first group, starting with works by ‘Older Villach's workshop’ and its founder Frederic of Villach, is characterized by plasters made of lime and sand, while the second, starting with Frederic's son, Johannes of Ljubljana, shows a composition of lime and crushed marble or lime-rock. Intonaco was applied everywhere by the system of giornatas, while lime-wash was rarely used. The analyses also made it possible to confirm/reject authorship hypotheses previously suggested by art historians.

Effect of different forms of silica on the physical and mechanical properties of gypsum plaster composites

Gypsum plaster/silica composites prepared by dry blending (0.2-10 %) natural sand, silica fume or silica gel and subsequently hydrated. Their physical and mechanical properties, including normal consistency, setting time, apparent porosity, bulk density and compressive strength, were determined after hydration for 7- and 28-days. The results indicated that adding different forms of silica lowered the bulk density and increased the normal consistency, setting time, apparent porosity and, to some limited extent, compressive strength of the composites. This improvement in properties can be attributed to the existence of silica in the interstitial pores in the hardened plaster matrices. While most of the composites revealed only scant rises in compressive strength, their composition was beneficial in so far as it included either a readily available low-cost constituent (sand) or industrial by-products. Consequently, the formed plaster-silica composites are of economic value, contribute to a cleaner environment by minimizing waste and can be used for applications where high porosity, lightweight units are required or recommended for low-cost buildings.

The hydrophobicity of renovation plaster in manufacturing technology optimized by statistical methods

In this paper, the influence of cement and some selected admixtures: redispersible polymer powder, air-entraining and hydrophobing agents, on the hydrophobicity of cured renovation plaster was analysed. The results were obtained experimentally. The result of capillary action (H) over a given period of time was used to evaluate the hydrophobicity of these materials. Statistical methods based on multiple regressions were employed to evaluate the influence of particular factors on this parameter. The analysis of the results showed that the suggested statistical models can be considered as very useful tools in optimizing the plaster composition thereby allowing for considerably shortening the time of preparation of production formulas for renovation plasters, thus lowering the costs of production. The analysis of the research results showed that the hydrophobicity of renovation plaster is mostly influenced by the weight amount of such ingredients as: cement, redispersible polymer powder, air-entraining and hydrophobing agents known also as water repellents. As expected, water repellent admixtures based on silicone show the greatest influence on the hydrophobicity of renovation plasters. An addition of only 0.6% of that admixture, at a relatively low content of cement in the mix design, accounted for a ca. 10% reduction in the capillary rise. Such a ratio ensures meeting the requirements of EN-998-1: 2012 [EN-998-1: 2012 Specification for mortar for masonry – Part 1: Rendering and plastering mortar] as for CS II resistance category.

Study on physical and chemical properties of external lime–sand plasters of some historical buildings

The article presents the results of laboratory tests of facade plasters from two selected sacred objects from the fourteenth and eighteenth centuries. In both buildings lime plaster was used, both internal and external facades. Plasters have different strength depending on the destination. In spite of the use of lime binders only, some of plasters, i.e. on plinths, are of considerable hardness and high resistance against weathering agents in comparison to other ones. In order to identify differences in the internal structure of different strengths plaster, samples were collected from different places and tests on physico-chemical characteristics were carried out. Due to the limited size and shape of the samples, physical properties such as absorbability, density and total porosity and granulometric analysis of the aggregate were marked. In addition, studies were made of mineral composition by differential thermal analysis and X-ray diffraction and chemical tests. The results obtained have allowed to clearly identify the nature of the binder and the mineral composition of the original plaster existing hikes, as well as reasons for the high hardness of some plaster. These results are of cognitive importance, as well as in the practical work of the revaluation of historical objects.

Infiltration Kinetics of Wetting in a Building Plaster and the Effect of Added Glass and Hemp Fibers

Capillary rise is an important cause of deterioration for plaster in building. This phenomenon has been studied by the tensiometric experimental technique. Structural and hydric characteristics of plaster have been determined. Decane, a perfectly impregnate fluid, has been used to calculate the porous constant characteristic called and other structural parameters like pore radius and specific surface. Evaluation of the sensibility of plaster for water has been evaluated in a second time. The angle constant and the capillary moisture content have been determined. A comparison between results for plaster and composite plaster with fiber has been done. The addition of glass and hemp fiber does not have important effect on hydric properties (angle constant), but we have observed influence on structural charecteristics (pore radius, porosity, and degree of heterogeneity).