bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental study on dynamic nanoindentation on structural weld zone
Authors: Nguyen Ngoc-Vinh , Pham Thai-Hoan 
Published: July 2020

Abstract
In this study, dynamic spherical indentation and finite element analysis were used to assess the strain rate sensitivity behavior of the SS400 structural steel weld zone. The influences of the loading rate on both yield strength and hardness of the base metal, heat-affected zone, and weld metal are studied using dynamic spherical nanoindentation. The strain rate sensitivity (SRS) of three microstructural phases in the weld zone was also determined using the hardness model, as a result, the SRS behavior in the weld zone was investigated. The relationship of the SRS to the minimum yield stress of the investigated weld zone was constructed and compared with the general trend reported for several types of structural steel in the literature. To verify the SRS behavior in the weld zone, the tensile loading experiments on the weld specimen and finite element (FE) simulation of the tensile process considering the SRS behaviors of base metal, heat affected zone, and weld metal were conducted. The comparison of the engineering stress-engineering strain curves obtained from the tensile experiment and FE analysis is then constructed. Thus, the SRS behavior of the SS400 structural steel weld zone was validated through experimental verification. The present study provided a basic methodology to dynamic nanoindentation on the weld zone, and the experimental results of this study can be used in the practical designs and to understand the strain rate sensitivity behavior of microstructural phases in the weld zone.
Eco - concrete made with phosphogypsum-based super sulfated cement
Authors: Ngoc Lam Nguyen 
Published: July 2020

Abstract
Phosphogypsum is an important environmental issue for all countries with phosphate and phosphoric acid industries from phosphate rock. The problem mainly stems from the difficulty in storing phosphogypsum. Therefore, the reuse of phosphogypsum in producing construction materials plays an important role to protect human health, to decrease the environmental pollution and to reduce the building materials cost. This research aimed at developing an eco concrete using super sulfated cement (SSC) in which the phosphogypsum was recycled. The present paper deals with the experimental investigation on slump number of fresh concrete, 28-day compressive strength characteristics of concrete using only 10% cement, 30% - 60% phosphogypsum and granulated blast furnace slag in binders named super sulfated cement with 3 different water-binder ratios of 0.45, 0.50 and 0.55… It is shown that Portland cement can be replaced with super sulfated cement based on Vietnam phosphogypsum to develop a good and hardened concrete to achieve economy; The compressive strength of concrete can achieve 20-40MPa. This value is enough for the use of the eco-concrete in the construction industry. The results also indicate that the increase of replacement of phosphogypsum in concrete lead to reduction in the compressive strength but do not affect too much in the case of slump number.
Effects of some factors on compressive strength of structural polystyrene concrete
Authors: Minh Duc Hoang , Ly Le Phuong 
Published: July 2020

Abstract
Structural polystyrene concrete is a lightweight composite consisting of lightweight expanded polystyrene aggregates immersed in a cement matrix. Compressive strength of structural polystyrene concrete can be increased by increasing compressive strength of cement matrix. Increasing strength of lightweight expanded polystyrene aggregate or improving interfacial transition zone between them is inefficient because the strength of polystyrene beans and their bond with cement matrix are negligible. In this case, the characteristic of normal aggregate in cement matrix plays an important role. The research results in this paper show that increasing of maximum particle size of normal aggregate in cement matrix significantly decreases the compressive strength of polystyrene concrete with given density. Therefore, the coarse aggregate smaller than 10 mm is recommended for structural polystyrene concrete with density less than 1,600 kg/m3.
Internal relation between hydration kinetic and endogenous shrinkage in an ettringite-based compound
Authors: Nguyen Ngoc-Lam 
Published: July 2020

Abstract
Ettringite based compound is a new materials used in construction because of high early-age strength, good chemical resistance, low CO2 emission…etc. However, research on not only the microstructure characteristics but also macrostructural properties and their internal relation is very limited. The aim of this study is to evaluate the relation between the microstructure characteristics such as chemical shrinkage and ettringite development by the infrared spectroscopy method with endogenous volumetric shrinkage in case of an ettringite based compound without setting regulators. The results indicated the evolution of the ettringite measured continuously by the infrared spectroscopy method corresponds to the development curves of the endogenous and chemical shrinkage. The swelling phenomenon expressed by volumetric shrinkage measurement related to the ettringite formation is verified by infrared spectroscopy and DRX technic. The greater the amount of ettringite formation, the more swelling of the compound increases.
Influence of mortar matrix on properties of light weight concrete with foam glass granules
Authors: Hoang V L 
Published: July 2020

Abstract
Foam glass granule (FGG) is commonly used as an aggregate for light weight aggregate concrete (LWAC). Because bulk gravity of FGG is much less than that of mortar matrix, segregation is tended to occur in LWAC mixtures. Mortar plays an important role in properties of LWAC with FGG. Therefore, this paper presents research results of influence of mortar matrix to properties of this type of concrete. In the study, the raw materials were FGG, But Son PC40 cement, Pha Lai fly ash and Sikament plasticizer named R4. The experimental results showed that with FGG content of 40% by volume and flow of mortar at 21- 22 cm, the LWC mixture was homogeneous and its slump was at 3.5- 5.5 cm. Simultaneously, the LWAC’s density was 1400-1500 kg/m3 and its compressive strength at 28 days was over 11 MPa.
Effect of temperature on the physico-mechanical and microstructure properties of cement pastes containing fly ash and silica fume
Authors: Phuong Do Thi , Lam Nguyen , Duc Vu Minh 
Published: July 2020

Abstract
This study aimed to investigate the effect of heat treatment on the physico-mechanical and microstructure properties of cement pastes containing fly ash (FA) and silica fume (SF). Portland cement (OPC) has been partially replaced by 5% SF and 20, 30, 40 and 50 wt.% FA. After curing, the hardened cement pastes were dried at 100°C for 24 hours, subjected to thermal treatment at the rate of 5°C/min, and heated at temperature of 200, 400, 600, 800, 1000°C for 2 hours, then cooled to room temperature in air. Finally, their bulk density and compressive strength were determined. X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods and were used for identification of the changes in the microstructure of the cement matrices. The results showed that the cement pastes containing 80% OPC + 5% SF + 15% FA is the optimum mix which gives a higher compressive strength and lower bulk density loss. Moreover, this optimum binder has the formation of inner fibers and crystalline needle like Wollastonite, Gehlenite which is responsible for the reduction in compressive strength loss from 800 up to 1000°C.
Influence of AAC grains on some properties of permeable pavement utilizing of CDW and industrial by-product
Authors: Tuan Ngo Kim , Dung Nguyen Tien , Minh Phan Quang , Tuan Nguyen Van , Kawamoto Ken 
Published: July 2020

Abstract
Construction and Demolition Waste (CDW) has been being accounted for a large amount of waste in urban areas around the world, especially for developing countries like Vietnam due to rapid urbanization and economic growth. The recycling and reuse of CDW are not only significant in reducing the consumption of natural materials but also can be a solution to improve the urban environment. In recent years, several studies have shown that the use of recycled materials from CDW in permeable pavement systems has a good effect on hydrological aspects and soil absorption capacity, thereby minimizing the risk of flooding and ground water depletion, increasing heat island effect. In this study, two main types of aggregates used are recycled aggregate (RA) and autoclaved aerated concrete (AAC) grains recycled from industrial by-products. The workability and forming ability are greatly affected by the moisture of the material before mixing. The results show that increasing AAC grain size leads to a slight decrease in the porosity of pervious concrete with the same AAC content. On the other hand, increasing AAC content from 5 to 10% results in significant fall in void content from 18% to 14.5%, thereby decreasing drainage speed. The compressive strength values show that without AAC, pervious concrete has the highest mechanical strength while increasing content and size of AAC leads to the compressive strength decreases. The surface temperature of pervious concrete samples is 4 – 5°C lower than that of normal concrete surface due to the increased effective surface area. The use of AAC grains helps to reduce the sample surface temperature by another 4°C.
Lightweight Geopolymer Concrete Panels for a wall in high-rise buildings: Technical- Economical- Environmental efficiency
Authors: Tong Kien T. 
Published: July 2020

Abstract
Brick and cement are two of the most used materials for a building wall, but the traditional brick and clinker production causes several environmental and human health impacts. Besides the demand of light-weight materials for the high-rise buildings is increasing more and more, these have encouraged the development of the new efficient materials to alternative the conventional brick. The objective of this study is to comparative technical and cost analysis as well as an environmental assessment of the wall structure used Lightweight Geopolymer Concrete Panels (LGCP). The results have revealed that the LGCP exhibits some superior engineering properties like as very low density and heat transfer coefficient, high strength,… The utilization of industrial wastes (fly ash-FA, Ground Granulated Blast furnace Slag-GGBS) as raw materials in LGCP production leads to reduce over 48% CO2 emission, and up to 17 times energy consumption, but still cheaper 42% construction cost to conventional bricks. The LGCP application is an important step to contribute better environmentally-friendly in particular and reach a sustainable development of the construction industry in general.
Contribution of calcium aluminates to the water resistance of hydrated calcium sulfates
Authors: Dung Nguyen Tien , Ambroise Jean 
Published: July 2020

Abstract
The water sensitivity of calcium sulphate materials has been known for a long time. In a humid atmosphere, plaster elements can become veiled under the action of their own weight because a low water uptake of 3% by mass can cause a drop in compressive strength of 50%. The low water resistance of calcium sulfates limits the applications of these materials to decorative elements or interior coatings despite their strengths compared to other construction materials: good fire resistance, low CO2 emission and low production cost. The objective of our research work is to evaluate the insensitivity of calcium sulfates to water by ettringitic binders containing calcium aluminate cement (CAC). Four types of calcium sulfates have been studied: natural gypsum, hemihydrate-α, hemihydrate-β, and synthetic anhydrite. In this research, only the majority binders of calcium sulfates will be studied: [70%, 80% of Calcium sultates with 30%, 20% of CAC]. The experiments results have shown that in high-calcium sulphate binders (≥ 70%), CAC helps reduce the water sensitivity of binders regardless of the nature of calcium sulphate by decreasing the total porosity, which leads to an increase in mechanical strengths; and reducing the connectivity of the pores, which contributes to reducing the entry of water and its movements into the material and consequently, reducing the degradation of the test pieces during immersion tests in the water.
Assessment of the compressive strength and strength activity index of cement incorporating fly ash
Authors: Trong Lam Nguyen 
Published: July 2020

Abstract
In recent years, the utilizations of industrial by-product as substitute for non-renewable material in cement and concrete production has received significant attention for sustainable development goals. In this study, fly ash blended cement was produced by replacing 5%, 10%, 15%, 20%, 25%, 30% and 35% by weight of Portland Cement with fly ash. In addition, the loss on ignition (LOI) content of fly ash, which used for the 20% replacement ratio, varies from 5 to 20% to assess the effect of unburnt carbon content in fly ash on the strength activity index of fly ash blended cement. The experimental results show that the addition of fly ash reduces the compressive strength of the mortar and strength activity index of fly ash blended cement at early ages. However, the presence of fly ash increases the strength of the mortar and the strength activity index of fly ash blended cement at longer ages when the fly ash replacement ratio is lower than 25%. The unburnt carbon in fly ash does not reduce the strength of the mortar and strength activity index of fly ash blended cement when its content does not exceed 20%.
Using iron alum in surface water treatment
Authors: Tuan Vo Anh , Tuan Pham Ngoc , Huy Huynh Quang , Thuy Duong Nguyen Phan , Xuan Vinh Phan Dinh , Duong Hoang Canh 
Published: July 2020

Abstract
Surface water contains clay, bacteria, dissolved metals, organic matter, color, other suspended solids. The purpose of coagulation and flocculation is to remove these suspended particles which ensure proper operation in treatment plant. Improper use of coagulant dosage affects water quality after treatment, cause operation problems and production costs. A study is being conducted at a surface water treatment plant at Dong Nai River with the capacity of 300,000 m3/day. The treatment process uses iron alum for coagulation and flocculation. Due to the high corrosion property of iron alum and the residue effects of the quality of treated water, it requires strict control in the treatment process as well as the chemical dosage. The main aim of this study is to determine appropriate amount of alum used for the coagulation-flocculation process. Research method is data collection including: turbidity, pH, flow rate of raw water, dosage of iron alum, lime, polymer used in current treatment process. Then, find the model using iron alum by linear regression analysis and BMA methods on R tool platform. Next, verify the appropriate linear regression model of iron alum by Jar test experiment. Results revealed that the BMA model is not suitable for the application because one Jar test results has a mean turbidity value greater than 4 NTU, which does not meet the water quality requirements after sedimentation tank according to the water treatment regulation. The linear regression analysis showed that raw water turbidity and season are two independent factors related to the alum dosage, of which these two factors explain about 78% of the differences that affect the coagulation-flocculation process. This study was successful in determining the appropriate iron alum dosage for the water treatment plant, which can be applied similarly to build appropriate chemical model for water surface water plants and raw water resources.
Modeling of water and air operation mode of sewer pipelines
Authors: Orlov Vladimir , Zotkin Sergey 
Published: July 2020

Abstract
An approach to complex accounting of hydraulic and aerodynamic parameters of a gravity sewage pipeline for the purpose of solution of its designing and effective operation problems has been presented herein. Consideration has been made of the variants which provide the subsurface space ventilation of a gravity pipeline in presence of aggressive and fetidly smelling gases by a mechanical air exchange system. Taking into account the complexity of manual processing of mathematical dependencies that describe the operation of a gravity pipeline and the processes that take place in it, the implementation of the problem has been achieved by developing and applying a special automated calculation program. At the corresponding values of air exchange, the dynamics of harmful gaseous substances released into the subsurface space of the gravity pipeline per unit of time, as well as the duration of their removal to the maximum permissible concentrations in the surrounding air space of populated areas, have been revealed.
Influence of ultrasound on the concentration of hydrogen ions in water
Authors: Vikulin Pavel , Vikulina Vera 
Published: July 2020

Abstract
The paper deals with the physical and chemical effects arising in water under the action of the energy of elastic vibrations of ultrasonic frequency in the cavitation mode. Cavitation state is characterized by the formation of the gas and air cavities - bubbles in the aquatic environment. The theory of occurrence of high temperatures at the moment of collapse of a cavitation bubble in water is given. It is noted that there is a dissimilation of the substance of free active radicals, dissociated and ionized molecules. The kinetics of chemical reactions in the ultrasonic field under the cavitation regime is described. Methods for obtaining ultrasonic cavitation in a liquid medium with a description of the generation of ultrasonic vibrations and a list of transducers and types of emitters are given. A relatively wide spectrum of radiated frequencies and instability of frequency and amplitude of oscillations are considered. The choice of ultrasonic generator is justified due to the necessary frequencies and intensities for the excitation of cavitation in water (f = 18-22 kHz, I = 2.0 W/cm2), technological considerations about the possibility of mounting the transducer in an existing production line, as well as safety and efficiency issues. The relevance, purpose and objectives of the work are formulated. The equipment and methods of experimental research are presented. Laboratory experimental studies on the effect of ultrasonic vibrations in the cavitation mode on the change of water pH were carried out. It is shown that bubbles formed in the ultrasonic field in the studied water collapse and create micro-explosions, shock waves and micro-flows. The results of studies on the change of pH in water are shown and the analysis of experimental data is performed. The experimental studies made it possible to substantiate the conclusions of this work and to formulate a conclusion about the influence of the ultrasonic field in the cavitation mode on the pH of the aqueous medium and its further application in water treatment processes.
Spread waves in a viscoelastic cylindrical body of a sector cross section with cutouts
Authors: Mirsaidov Mirziyod , Safarov Ismoil , Boltayev Zafar , Teshaev Mukhsin 
Published: July 2020

Abstract
In this article an analysis of well-known works related to wave propagation and dispersion dependences in a cylindrical waveguide are presented. A mathematical model, methodology and algorithm for solving the problem of wave propagation in a cylindrical waveguide, having a sector cut are developed. The obtained equations are solved by the orthogonal sweep method in combination with the Mueller and Gauss methods. The dispersion relation for a viscoelastic cylindrical waveguide, having a sector cut in cross section at an arbitrary angle is obtained. Based on the obtained results, it was found that, there are no waves in the elastic cylinder of a sector section with real parts of the phase velocity. It has been established that, in the case of a wedge-shaped viscoelastic cylindrical panel, for each mode, there are limiting wave propagation velocities and they change with a change in the radius of curvature. The spectral sets of normal waves with an increase in the angular parameter of the sector cut-out, corresponding to lower non-zero frequencies of wave locking, slowly decrease.
Centralization of gas supply systems based on butane-air mixture
Authors: Osipova Nataliya , Kultyaev Svyatoslav 
Published: July 2020

Abstract
The expansion of the construction of cottage villages, isolated settlements in ecologically clean areas, away from large cities, as well as the provision of gas to the settlements of the eastern part of the Russian Federation, sets the task of developing autonomous gas supply systems. A significant deterrent to the development of autonomous gas supply systems based on butane mixtures with air is their high cost and the absence of scientifically sound recommendations for choosing system parameters. To develop scientifically sound recommendations for the design of systems, considering all the factors of influence that ensure the optimal cost of gasification and subsequent maintenance by the consumer, additional studies are necessary. The article considers the choice of optimal centralization of gas supply systems based on a mixture of butane with air to determine the minimum cost of construction and operation for consumers. the systems analysis, mathematic model methods with calculation of optimal values in the presence of corresponding limits and the methods of material correlation processing are used. The data have been obtained for effective centralization of gas supply systems based on butane-air mixture. The criteria are set which influence the optimum number of houses connected to a tank installation, such as population density in a gas supplied area, climatic features of an area, a type of consumer’s gas-using equipment and a form of settlement development. As a result of the research, the optimum number of apartments has been determined for gas supply to a settlement connected to a tank installation. These recommendations will make it possible to increase efficiency of gas supply source selection and consumer connecting to a gas sup-ply network at minimum cost for consumers
Natural ventilation and aerodynamics of orthodox churches
Authors: Kochev Alexey , Sokolov Mikhail , Lushin Kirill 
Published: July 2020

Abstract
The paper devoted to introducing of theory and practice results of natural ventilation and properties of external aerodynamics of orthodox churches research. The features of the movement of air flows inside the temple are considered. On the example of the Transfiguration Cathedral, the analysis of the fields of aerodynamic coefficients is introduced.