Effect of Viscosity Modifying Agent on the Performance of Hybrid Bio-Based Concrete

An experimental investigation was conducted in order to study the water absorption, mechanical performance, thermal properties and durability of hybrid hemp-rapeseed composite materials. The hybrid composite material is made with 50% hemp shives and 50% rapeseed fibres. The purpose of this study is to investigate the influence of the incorporation of viscosity modifying agent (VMA) on hybrid concrete. Four mixes were made for: shuttered walls and roof insulation with and without VMA. The water absorption of the hybrid composite fibres was, first, measured. The compressive strengths of these mixes at 7 and 28 d were then determined in order to compare the mechanical behaviour of the hybrid composite materials made with VMA. In addition, the capillary absorption and coefficient of thermal conductivity were also measured. The results revealed that VMA improved the performance of the hybrid concrete.

Heat-insulating porous material based on glauconite-containing sands and aleurites of the Novodvorskoye deposit of the Republic of Belarus

The results on the research of heat-insulating porous ceramic materials produced using overburden rocks of the Novodvorsk deposit of Pinsk district of the Brest region as the main component of raw materials are presented in the study and the use of bulk rock consisting of glauconite sands and aleurites is recommended. Low-melting clay, basalt and a blowing agent are used as additional components, rational combination of which would ensure the forming ability of ceramic masses and the required set of the physicochemical properties of the material. The dependence of the bulk density, swelling coefficient, coefficient of thermal conductivity on the chemical and mineral composition of the used and raw materials is established, wich is the criteria for choosing composition with the maximum use of overburden and the necessary plasticity of the ceramic mass required for the molding process of raw granules. The obtained results can serve as a basis for the large-scale use of not only the minerals of the Novodvorsk deposit (basalts and tuffs), but also associated – glauconite-containing overburden. This will make a significant contribution to the expanding the mineral resource base of the Republic of Belarus.

Modeling the properties of lightweight polymer concrete produced from polyvinyl chloride and combined heat and power plant waste

Although concrete based on mineral binders is most commonly used in construction, polymer concrete is on the rise lately. This is due to the fact that polymer concrete allows to expand concrete usage in civil and industrial construction thanks to its properties. However, there is extensive research on including thermoplastic polymer. Construction polymer concrete materials have high compressive strength, as well as atmospheric, cold and chemical resistance, thus resulting in long term lifetime. This paper suggests a technological process of producing concrete based on polyvinyl chloride and lightweight porous aggregate, e. g. fly ash that comes from Vladimir combined heat and power plant (used to run on coal). There are up to 80 thousand tons of this aggregate in stock. It turns out that technological parameters of this process are strongly intertwined with compound. Research indicates that lightweight polymer concrete based on polyvinyl chloride and fly ash can be achieved under certain technological parameters. A new polymer concrete was created as a result of this research having the following properties: density - 800-830 kg/m3, compressive strength - 12-13 MPa, impact strength -16-18 kg/m2, coefficient of thermal conductivity - 0.16-0.18 Wt/m.K, frost resistance - at least a 100 cycles.

Calculation and experimental analysis of heat transfer of assemblies of ribbed heat exchange elements

The results of thermal-hydraulic and strength tests of finned tube assemblies welded from KP 20 elements of four sizes are presented. The elements are representing by steel plate 0.4 mm in thickness, covered with a copper film 0.025 mm in thickness. One or two conical necks 17 mm long are extended in the plates. A set of placed in each other cones form a welded finned tube 23/20 mm with a toothed inner surface. As a result of the tests: high strength characteristics of these assemblies were demonstrated (internal pressure of burst under normal conditions is 40 MPa, resistance to sudden changes in temperature and freezing of water in “pipes”); a high average coefficient of thermal conductivity in the thickness of the ribs was confirmed at the level of 75 W/(m×K); the increase in the intensity of the heat transfer process is 2.15 times with the help of technological protrusions on the inner surface of the “pipe” to a turbulent single-phase flow in comparison with the calculated values for “smooth” pipes with a moderate increase in hydraulic resistance; the method of heat-hydraulic calculation of heat exchangers consisting of such “pipes” is proposed. The method is based on the ratios set out in the regulatory document “RD 24.035.05-89”. Thermal and hydraulic calculation of NPP heat exchanging equipment”, with amendments considering the high degree of finning of the tested “pipes” and the asymmetry of the edges of the ribs relative to the axis of the “pipes” bearing pressure, as well as the change in the value of the correction for the smallness of the tube bundle — we also identified areas of effective use of assemblies tested sizes of elements KP 20.

Preparation of Superhydrophobic Surfaces Based on Rod-Shaped Micro-Structure Induced by Nanosecond Laser

Solid–liquid frictional resistance is mainly attributed to the adhesion caused by the boundary layer effect. Superhydrophobic surfaces are expected to be an effective method to reduce frictional resistance. In this paper, a rod-shaped micro-structure was prepared on surfaces of Al alloy (5083) and Ti alloy (TC4) by line-by-line scanning with nanosecond laser. The inherent properties of the metal materials—such as their coefficient of thermal conductivity (CTC) and specific heat capacity (SHC)—had a major influence on the surface morphology and shape size of the rod-shaped micro-structure. Both two metals showed apparent oxidation on their surfaces during laser ablation, however, the degree of surface oxidation of the Al alloy was greater than that of the Ti alloy due to its more fragmentary rod-shaped micro-structure. The laser-treated surfaces could turn from hydrophilic to hydrophobic or even superhydrophobic after being left in the air for 20 days, which might be caused by the adsorption of low-surface energy matter in the air. In addition, the contact angle of the Al alloy was larger than that of the Ti alloy, which is due to the larger ratio of height to width of the micro–nano composite rod-shaped micro-structure on the surface of the Al alloy.

Thermal Properties of Manganese Chloride Salt Reinforced [PVA: PVP] Blend Films

The casting process was used to make pure [PVA: PVP] polymer blend film and MnCl2.4H2O salt augmented polymer blend film at varied weight ratios ((10, 20, 30, 40, 50) wt. percent). The influence of salt weight ratio on the thermal characteristics of [PVA: PVP] polymer blend films augmented with MnCl2.4H2O salt was also investigated. The coefficient of thermal conductivity of the [PVA: PVP] polymer blend films reinforced by MnCl2.4H2O was found to be higher in the experimental results. As the weight ratio of MnCl2. 4H2O grows and then falls, the MnCl2.4H2O salt increases and then reduces erratically. As the concentration of MnCl2.4H2O salt rises, it is discovered that the thermal conductivity coefficient of whole polymer mix films is extremely low. As a result, such films could be utilized as heat-insulation shields. The temperature of glass transition and crystal melting temperature of [PVA: PVP] polymer blend films reinforced by MnCl2.4H2O salt change as the weight ratio of MnCl2.4H2O salt increases.

THE EFFECT OF CRYSTALLINITY ON THE THERMAL CONDUCTIVITY OF POLYMERS

The aim of this research is investigating the direct effect of crystallinity of thermoplastic polymers on their thermal conductivity values. The study has included many materials, namely: polyoxymethylene (POM), high-density polyethylene (HDPE), low-density polypropylene (LDPE), polypropylene (PP), polyamide (PA) and polyethylene terephthalate (PET). The degrees of crystallinity ranged from high-values (60-70%), mid-values (30-40%) and low-values (10-20%). The work has done theoretically and experimentally. Theoretical work has used mathematical function extracted from reliable empirical relationships. The experimental work has included: manufacturing the specimens; specifying the cooling procedure in order to get the required degree of crystallinity; measuring the coefficient of thermal conductivity for different polymers at various conditions; and finally analyze the data and introduce the experiences obtained from the investigation. In general, theoretical values as well as experimental data were both behave similarly with respect to the variation of thermal conductivity with the degree of crystallinity. The results show that by increasing the degree of crystallinity the thermal conductivity of the polymer has increased by 10-20%.

Comparison of Thermal Insulation Concrete Panel Yield Based on Natural Fibres: A Review

Over time, many researchers have conducted studies to investigate the construction sector by assessing those related to energy, environmental and economic problems to find ways to improve global sustainability. The studies on the use of natural fibers: wheat, date palm and hemp as an insulating material in concrete panel yields have been conducted through ten previous research studies. In the market, there are various types of thermal insulation materials but these materials are sold at high prices and even worse some of them contain harmful chemicals that can threaten the health of consumers. This study is intended to identify ten previous research studies on the use of natural fibers in concrete panel yield as thermal insulation materials. Also, to analyse the data of density and coefficient of thermal conductivity accumulated through Microsoft Excel and propose the best concrete panels yield between these three types of natural fibers. The research was based on the value of density and coefficient of thermal conductivity of concrete panel yield. The results reveal that the presence of natural fibers in concrete panels can insulate heat well. The lowest thermal conductivity coefficient obtained from concrete of Hemp Fibre Gypsum (HG) with 0.051 W/mK. The composition of 35g of hemp fiber, 200g of gypsum and 130ml of water has shown that the amount of fibre and binder used plays an important role in determining the value of density and thermal conductivity. Finally, based on the analysis that has been conducted, found that density and thermal conductivity are inversely proportional when there is a change in the composition of fibers and binders in the concrete panel yields.

Improving Indoor Air Quality by Using Sheep Wool Thermal Insulation

Currently, the need to ensure adequate quality of air inside the living space but also the thermal efficiency of buildings is pressing. This paper presents the capacity of sheep wool heat-insulating mattresses to simultaneously provide these needs, cumulatively analyzing efficiency indicators for thermal insulation and indicators of improving air quality. Thus, the values obtained for the coefficient of thermal conductivity, and its resistance to heat transfer, demonstrate the suitability of their use for thermal insulation. The results of the permeability to water vapor characteristics on the sorption/desorption of water, air, demonstrate the ability to control the humidity of the indoor air and the results on the reduction of the concentration of formaldehyde, demonstrating their contribution to the growth of the quality of the air, and to reduce the risk of disease in the population.