scholarly journals Suitability of modified low carbon Roman cements for architectural restoration

2021 ◽  
Vol 280 ◽  
pp. 07002
Author(s):  
Myroslav Sanytsky ◽  
Tetiana Kropyvnytska ◽  
Roman Kotiv ◽  
Mykola Bevz ◽  
Stanislav Fic
Keyword(s):  
Setting Time ◽  
High Surface ◽  
Weather Conditions ◽  
High Porosity ◽  
Low Carbon ◽  
Initial Strength ◽  
Building Facades ◽  
Hydraulic Binder ◽  
History Of ◽  
Architectural Restoration

Article is devoted to the investigation of suitability of low carbon Roman cement for restoration and finishing works. The history of the development of Roman cement as a natural hydraulic binder, which was commonly used to decorate building facades in the 19th and early 20th centuries, is presented. The properties of mortars based on Roman cement make it an excellent product for architectural restoration and conservation, as they are characterized by fast setting, high porosity typical for lime mortars, high resistance to weather conditions, high initial strength. At the same time, due to the high surface activity and increased water demand for cement, with the age of hardening, shrinkage deformations can develop, which leads to the formation of main cracks on the surface of the products. It is shown that the addition of gypsum is an effective regulator of the setting time of Roman cement and contributes to an increase in the strength of the cement paste. Analogs of Roman cement based on multicomponent cement binders modified with plasticizing and air-entraining additives are presented.

Mechanical Properties of Mortars Based on Roman Cement with the Addition of Power Plant Fly Ash

2020 ◽  
Vol 868 ◽  
pp. 39-44
Author(s):  
Jana Daňková ◽  
Tereza Majstríková ◽  
David Bujdoš ◽  
Pavel Mec
Keyword(s):  
Fly Ash ◽  
Power Plant ◽  
Raw Materials ◽  
Strength Increase ◽  
Low Carbon ◽  
Slow Increase ◽  
Initial Strength ◽  
Hydraulic Binder ◽  
Long Lifetime ◽  
Reference Mixture

Roman cement is a historic hydraulic binder, prepared by firing of limestone with high proportion of clay minerals, usually at temperatures below the sintering point. The firing temperatures of Roman cements range from 800 to 1200°C. At present, this binder is considered to be a promising material with a low carbon footprint and a long lifetime. The properties of Roman cement are influenced by many factors, especially raw materials composition and firing conditions. On the other hand, a disadvantage of mortars based on Roman cement is a slow increase of initial strength. In this paper, the influence of power fly ash admixture on the dynamics of initial strength increase was experimentally investigated. The characteristics of mortars with admixtures were compared with the properties of reference mortar without admixtures. The Roman cement Vicat Prompt TM Natural Cement (manufactured by Vicat SA, French company) was used as a binder. Based on the results of the experiment it can be stated that mortars with the admixture of power plant fly ash show higher dynamics of the increase of initial strengths than the reference mixture.

THE EFFECT OF COMPOSITION CHANGE IN SOL-GEL SYNTHESIZED PSC

2008 ◽  
Vol 20 (01) ◽  
pp. 53-59
Author(s):  
Wen-Hsi Wang ◽  
Yuan-Ling Lee ◽  
Chun-Pin Lin ◽  
Feng-Huei Lin
Keyword(s):  
Setting Time ◽  
Sol Gel ◽  
Hydration Product ◽  
Xrd Pattern ◽  
Ph Variation ◽  
Initial Strength ◽  
Filling Materials ◽  
Retrograde Filling ◽  
Significant Difference ◽  
Sol Gel Process

Modified calcium silicate cement had previously been developed as a dental retrograde filling. It had great sealing ability, good biocompatibility, and anti-bacterial properties. However, its clinical application was limited by a long setting time and poor handling property. In previous study,1, 2 the setting property of PSC was greatly improved due the sol-gel process, without the addition of transition metal element. In this study, different ratio of starting material of PSC was prepared. The composition of each group was also altered with the ratio of the starting materials according to the result of XRD pattern. There is no significant difference in pH variation profile between each group. Even though low C 3 S / C 4 AF ratio (DX631 and DX541 groups) possessed high initial strength at first 24 hours after hydration, there was no increase in strength ever since according to the result of microhardness. However, the groups with high C 3 S / C 4 AF ratio (DX811 and DX721 groups) possessed relatively low initial strength at 24 hours after hydration, but the strength increased rapidly and continuously at least for the next six days of hydration. Moreover, the peak intensity of hydration product (Portlandite) on XRD pattern in DX811 group was much higher than other three groups, and this was also in agreement with the result of microhardness. DX811 group is determined to be the optimal one for the further development in the application as root-end filling materials.

Highly stable metal-organic framework UiO-66-NH2 for high-performance triboelectric nanogenerators

2021 ◽  
Author(s):  
Yong-Mei Wang ◽  
Xinxin Zhang ◽  
Dingyi Yang ◽  
Liting Wu ◽  
Jiaojiao Zhang ◽  
...  
Keyword(s):  
High Performance ◽  
Metal Organic Framework ◽  
High Surface ◽  
High Surface Area ◽  
Triboelectric Nanogenerator ◽  
High Porosity ◽  
Chemically Modified ◽  
Metal Organic ◽  
Triboelectric Nanogenerators ◽  
Organic Framework

Abstract The high porosity, controllable size, high surface area, and chemical versatility of a metal-organic framework (MOF) enable it a good material for a triboelectric nanogenerator (TENG), and some MOFs have been incorporated in the fabrication of TENGs. However, the understanding of effects of MOFs on the energy conversion of a TENG is still lacking, which inhibits the improvement of the performance of MOF-based TENGs. Here, UiO-66-NH2 MOFs were found to significantly increase the power of a TENG and the mechanism was carefully examined. The electron-withdrawing ability of Zr-based UiO-66-family MOFs was enhanced by designing the amino functionalized 1,4-terephthalic acid (1,4-BDC) as ligand. The chemically modified UiO-66-NH2 was found to increase the surface roughness and surface potential of a composite film with MOFs embedded in polydimethylsiloxane (PDMS) matrix. Thus the total charges due to the contact electrification increased significantly. The composite-based TENG was found to be very durable and its output voltage and current were 4 times and 60 times higher than that of a PDMS-based TENG. This work revealed an effective strategy to design MOFs with excellent electron-withdrawing abilities for high-performance TENGs.

Thermal and mechanical characterization of a new material based on two gypsums from different localities : High Atlas of Marrakech and Safi Basin, Morocco

2021 ◽  
Author(s):  
imane baba ◽  
Mounsif Ibnoussina ◽  
Omar Witam ◽  
Latifa Saadi
Keyword(s):  
Setting Time ◽  
Density Measurement ◽  
Mechanical Resistance ◽  
Mechanical And Thermal Properties ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
High Atlas ◽  
New Material ◽  
Indoor Comfort

<p>Over the last few decades, the construction industry has become interested in materials that are durable, environmentally friendly and easily recyclable. This interest is due to the advantages these materials offer, among others local availability, low carbon footprint, energy efficiency and indoor comfort. The objective of this work is to study the properties of plasters prepared from a mixture of two types of gypsum. We were interested in the evolution of thermal conductivity, mechanical resistance and setting time as a function of the percentage of addition.</p><p>Two types of gypsum were studied, the first one belongs to the Safi basin and the second one comes from the High Atlas of Marrakech.</p><p>The characterization of the gypsums was necessary to determine its physical and geotechnical properties, its mineralogy, its thermal behavior and its microscopic structure. Several analyses were developed such as density measurement by pycnometer, X-ray diffraction, infrared spectroscopy and scanning electron microscopy.</p><p>We have made samples, of standardized dimensions, of mixtures based on both types of plaster. The water/gypsum mass ratio was set at 0.75.</p><p>The results revealed that the properties of gypsum as well as the percentage of addition affect the mechanical and thermal properties and the setting time of the composite material. The addition of the High Atlas gypsum of Marrakech allowed improving the material in terms of thermal insulation. The results of the other tests will be communicated later.</p>

Increasing Hardness of Surface Layer of Low-Carbon Steel by Account of Plasma Treatment of Coating Modification

2021 ◽  
Vol 316 ◽  
pp. 794-802
Author(s):  
Andrey E. Balanovsky ◽  
Van Trieu Nguyen
Keyword(s):  
Surface Layer ◽  
Thermal Treatment ◽  
Plasma Treatment ◽  
Plasma Heating ◽  
High Surface ◽  
Surface Hardness ◽  
High Hardness ◽  
Diffusion Region ◽  
Low Carbon ◽  
Wide Range

The Purpose of paper is to conduct studies to assess the possibility of increasing the hardness of the surface layer of steel St3 grade by plasma heating of the applied surface coating containing powder alloy PR-N80X13S2R. Mixtures of pasta were divided into 2 groups: for furnace chemical-thermal treatment and plasma surface melting. The study of the microstructure showed a difference in the depth of the saturated layer, depending on the processing method, during chemical-thermal treatment-1 mm, plasma fusion - 2 mm. The results of measuring the surface micro-hardness showed that, the obtained coating from a mixture of PR-N80X13S2R + Cr2O3 + NH4Cl has a uniform high surface hardness (31-64 HRC), from a mixture of only PR-N80X13S2R - the surface hardness varies in a wide range (15-60 HRC). The study of the microhardness of the cross section of the surface layer showed that, the diffusion region: from a mixture of powder PR-N80X13S2R + Cr2O3 + NH4Cl has uniform hardness (450-490 HV); from a mixture of PR-N80X13S2R - hardness increases in the depth of the molten region (from 300 to 600 HV), and sharply decreases in the heat affected zone (210-170 HV). The use of PR-N80X13S2R alloy powder as the main component in the composition of the paste deposited on the St3 surface during plasma treatment leads to the formation of a doped surface layer with high hardness.

Research and Design of Energy-Saving and Environmental-Protection Full Evaporative Air Cooler

2013 ◽  
Vol 368-370 ◽  
pp. 400-410
Author(s):  
Li Xin Shang ◽  
Chuan Yi Zhou ◽  
Yun Tao Jing
Keyword(s):  
Energy Conservation ◽  
Automatic Control ◽  
Environmental Protection ◽  
Main Body ◽  
Low Carbon ◽  
Low Carbon Economy ◽  
Air Cooler ◽  
History Of ◽  
Research And Design ◽  
Carbon Economy

Our country is in a low carbon economy development period, this paper described the whole evaporative air cooler is based on energy conservation and environmental protection thinking of development, this paper described the development history of air cooler in energy conservation and environmental protection, the main body of the thinking of equipment design and each index assessment, in a large number of experimental data are put forward on the basis of the concept of "full evaporation", according to the requirements of the indicators and process requirements of equipment parts for detailed design of equipment, automatic control design, form the mechanical and electrical integration, energy conservation and environmental protection, automatic control, full evaporative air cooler and heat exchange equipment.

scholarly journals Sizing and implementation of Photovoltaic Water Pumping System for Irrigation

2018 ◽  
Vol 7 (1) ◽  
pp. 54
Author(s):  
Santosh S. Raghuwanshi ◽  
Vikas Khare
Keyword(s):  
Fuzzy Logic Controller ◽  
Setting Time ◽  
Weather Conditions ◽  
Pi Controller ◽  
Voltage Source ◽  
Solar Photovoltaic ◽  
Pump System ◽  
Pumping System ◽  
Water Pumping ◽  
Perturb And Observe

<p>Solar photovoltaic systems convert energy of light directly into electrical<br />energy. This work presents, a process to compute the required size of the<br />stand-alone solar photovoltaic generator based water pumping system<br />for an existing area. In addition solar photovoltaic generator is<br />connecting voltage source inverter fed vector controlled induction<br />motor-pump system. Perturb and observe are used for harvesting<br />maximum power of PV generator in between buck-boost DC converter<br />and inverter system. In this paper system result is validated by fuzzy<br />logic system and compare with variable frequency drives based PI<br />controllers, driving motor-pump system. The operational performance<br />at 60 m head, VFD based controllers in terms overshoot and setting time<br />and also analysis performance of motor-pump set under different<br />weather conditions. By assessment of system we find that speed and<br />torque variation, overshoot and settling time is more with PI controller,<br />Fuzzy logic controller (FLC) performance have dominance to VFD<br />based PI controller.</p>

scholarly journals Performance Assessment of Motorized Solar Photovoltaic Louvers System Using PVSYST Software

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Hussein Safwat Hasan ◽  
Humor Hwang
Keyword(s):  
Solar Energy ◽  
Weather Conditions ◽  
Photovoltaic System ◽  
Solar Photovoltaic ◽  
Market Penetration ◽  
Simulation Tools ◽  
Building Facades ◽  
Internal Network ◽  
Potential Benefits ◽  
Solar Photovoltaic System

In the realm of technological market penetration of solar photovoltaiclouvers (PVL) addressing environmental difficulties and the industrialrevolution, a new avenue of renewable energy is introduced. Moreover,solar energy exploitation through building façades was addressedthrough motorized solar photovoltaic louvers (MPVL). On the otherhand, proponents exalted the benefits of MPVL overlooking the typicalanalyses. In this communication, we attempted to perform a thoroughindustrial system evaluation of the MPVL. This communication presentsa methodology to validate the industrial claims about MPVL devices andtheir economic efficiency and the insight on how geographical locationinfluences their utilization and augment their potential benefits. This taskis carried out by evaluating the extent of solar energy that can be harvestedusing solar photovoltaic system (PVSYST) software and investigatingwhether existing product claims are associated with MPVL are feasible indifferent locations. The performance and operational losses (temperature,internal network, power electronics) were evaluated. To design and assessthe performance of different configurations based on the geographicalanalogy, simulation tools were successfully carried out based on differenttopographical locations. Based on these findings, various factors affect theemployment of MPVL such as geographical and weather conditions, solarirradiation, and installation efficiency. tt is assumed that we successfullyshed light and provided insights into the complexity associated withMPVL.

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