scholarly journals Innovative ways of concrete water supply structures repair with composite materials

2021 ◽  
Author(s):  
O. A. Baev ◽  
◽  
Yu. M. Kosichenko ◽  
Keyword(s):  
Water Supply ◽  
Bearing Capacity ◽  
Water Permeability ◽  
Concrete Structures ◽  
Protective Layer ◽  
Bentonite Clay ◽  
Impregnation Method ◽  
Advantages And Disadvantages ◽  
Technical Developments ◽  
Technical Solutions

Purpose: modern scientific and technical developments for repairing concrete structures and lined water supply structures, including those for which patents for inventions have been obtained are considered. Some of the considered technical solutions can be attributed to innovative developments. Materials and Methods: the known methods of repairing concrete structures of water-supply structures and linings were studied as research materials, their advantages and disadvantages were noted. Particular attention is paid to technical solutions for which patents for inventions have been obtained. Results: damage repair of concrete linings of water-supply structures in the form of cracks and destruction of expansion joints is most common, since at the same time water permeability decreases, and the bearing capacity increases. Repair by surface impregnation method is carried out to strengthen the protective layer of reinforced concrete structures to a depth of 15–35 mm. Repair of local disturbances is carried out manually at a depth of destruction less than 0.1 m. Areal disturbances with an area of more than 1 m² and a destruction depth of more than 0.1 m are recommended to be repaired mechanically. Invention no. 1477877 proposes a method for repairing construction structures and facilities, which is carried out by the method of pressure injection of repair compounds, they increase the quality of repair due to the reliability of defective zones filling. Innovative methods of facing repairing include sealing damage by injecting bentonite mortar during data remote transmission from humidity sensors to a personal computer (patent no. 2612431), as well as a method of sealing the joints of facings, including an anti-filtration bundle in the form of a hollow cylinder filled with bentonite clay (patent no. 2598635). Conclusions: repair of damage to concrete water-supply linings is the most common, since the water permeability of the concrete structure decreases at the same time as the bearing capacity changes.

Fire Resistance Of Concrete Structures With Composite Rod Reinforcement

2019 ◽  
pp. 50-55 ◽  
Keyword(s):  
Bearing Capacity ◽  
Fire Resistance ◽  
Concrete Structures ◽  
Protective Layer ◽  
Maximum Temperature ◽  
Regulatory Requirements ◽  
Composite Rod ◽  
The Moment ◽  
Normative Value ◽  
Composite Reinforcement

The use of composite rod reinforcement makes it possible to ensure the durability of reinforced concrete structures, operated under aggressive conditions. The use of composite reinforcement in concrete structures requires solving the problem of fire resistance of this class of structures. The fire resistance of the composite rod reinforcement is determined by the moment of softening of the composite rod matrix as a result of heating under fire conditions. The maximum temperature for various composite materials is 150 °Ñ – 250 °C. When designing, it is necessary to ensure the normative value of the limit of fire resistance of structures. For the bearing structures of the frame, the fire resistance limit corresponds to the moment of loss of the bearing capacity, for the intermediate floors – the loss of bearing capacity, integrity and thermal insulation ability. The main factor that provides the fire resistance of concrete structures with rod composite reinforcement is the thickness of the protective layer of concrete which ensures the joint operation of composite rods with concrete. Diagrams of the temperature change over the thickness of a concrete structure are presented, on the basis of them the methodology for the assignment of the value of the protective layer of concrete for the core composite reinforcement for different designs with due regard for the duration of fire effect in case of fire is proposed. The nomenclature of structures in which it is possible to use the rod composite reinforcement with the provision of regulatory requirements for the limit of fire resistance is determined.

Investigating artificial groundwater recharge to ensure the water supply to the city of Graz

2008 ◽  
Vol 3 (3) ◽  
Author(s):  
Wilhelm Tischendorf ◽  
Hans Kupfersberger ◽  
Christian Schilling ◽  
Oliver Gabriel
Keyword(s):  
Water Supply ◽  
Groundwater Recharge ◽  
Water Demand ◽  
Bulk Water ◽  
Retention Rates ◽  
Subsurface Water ◽  
Artificial Groundwater Recharge ◽  
Advantages And Disadvantages ◽  
Water Recharge ◽  
Water Supply Company

Being Austria's fourth largest water-supply company, the Grazer Stadtwerke AG., has ensured the successful water-supply of the Styrian capital with 250.000 inhabitants for many years. The average daily water demand of the area amounts to about 50,000 m3. Approximately 30 % of the total demand is covered by the bulk water supply from the Zentral Wasser Versorgung Hochschwab Süd. The waterworks Friesach and Andritz, which cover the additional 70 % of the water demand, operate by means of artificial groundwater recharge plants where horizontal filter wells serve as drawing shafts. The groundwater recharge systems serve to increase the productivity of the aquifer and to reduce the share of the infiltration from the Mur River. Protection areas have been identified to ensure that the water quality of the aquifer stay at optimal levels. The protection areas are divided into zones indicating various restrictions for usage and planning. Two respective streams serve as the source for the water recharge plants. Different infiltration systems are utilised. Each of the various artificial groundwater recharge systems displays specific advantages and disadvantages in terms of operation as well as maintenance. In order to secure a sustainable drinking water supply the recharge capacity will be increased. Within an experimental setting different mixtures of top soils are investigated with respect to infiltration and retention rates and compared to the characteristics of the existing basins. It can be shown that the current operating sand basin with more than 90% grains in the range between 0.063 and 6.3 mm represents the best combination of infiltration and retention rates. In future experiments the performance of alternative grain size distributions as well as planting the top soil will be tested. Additionally, in order to optimize the additional groundwater recharge structures the composition of the subsurface water regarding its origin is statistically analyzed.

Cassava Processing in Sub-Saharan Africa: the Implications for Expanding Cassava Production

1994 ◽  
Vol 23 (3) ◽  
pp. 197-205 ◽  
Author(s):  
Felix Izu Nweke
Keyword(s):  
Food Security ◽  
Water Supply ◽  
Sub Saharan Africa ◽  
Wide Range ◽  
Intensive Use ◽  
Cassava Production ◽  
Sub Saharan ◽  
Processing Techniques ◽  
Technical Solutions ◽  
Poor Soil

Cassava makes an important contribution to improving food security and rural incomes in sub-Saharan Africa, as it is tolerant of drought and poor soil and its cultivation does not require much labour. However, the fresh roots are bulky and perishable and need to be processed before they can be marketed; processing also removes the cyanogens which make many varieties poisonous in their raw form. Cassava roots are turned into granules, flours, pastes and chips, with a wide range of flavours and appearances for different areas and markets. Many different processing techniques are used, some of which make intensive use of fuelwood while others require a plentiful water supply. These requirements, as well as the need for a good transport and marketing infrastructure, limit the expansion of cassava production in sub-Saharan Africa, but technical solutions are being found.

Experimental Studies on Axially Loaded Concrete Columns Confined by Different Materials

2008 ◽  
Vol 400-402 ◽  
pp. 513-518 ◽  
Author(s):  
Yong Chang Guo ◽  
Pei Yan Huang ◽  
Yang Yang ◽  
Li Juan Li
Keyword(s):  
Bearing Capacity ◽  
Glass Fiber ◽  
Failure Modes ◽  
Experimental Studies ◽  
Concrete Columns ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Advantages And Disadvantages ◽  
Axially Loaded ◽  
Normal Strength

The improvement of the load carrying capacity of concrete columns under a triaxial compressive stress results from the strain restriction. Under a triaxial stress state, the capacity of the deformation of concrete is greatly decreased with the increase of the side compression. Therefore, confining the deformation in the lateral orientation is an effective way to improve the strength and ductility of concrete columns. This paper carried out an experimental investigation on axially loaded normal strength concrete columns confined by 10 different types of materials, including steel tube, glass fiber confined steel tube (GFRP), PVC tube, carbon fiber confined PVC tube (CFRP), glass fiber confined PVC tube (GFRP), CFRP, GFRP, polyethylene (PE), PE hybrid CFRP and PE hybrid GFRP. The deformation, macroscopical deformation characters, failure mechanism and failure modes are studied in this paper. The ultimate bearing capacity of these 10 types of confined concrete columns and the influences of the confining materials on the ultimate bearing capacity are obtained. The advantages and disadvantages of these 10 types of confining methods are compared.

A numerical approach to predict soil bearing potential for isolated footing

2021 ◽  
Author(s):  
Gilbert Hinge ◽  
Jayanta Kumar Das ◽  
Biswadeep Bharali
Keyword(s):  
Bearing Capacity ◽  
Shear Failure ◽  
Correlation Coefficients ◽  
Failure Criteria ◽  
Numerical Approach ◽  
Ultimate Bearing Capacity ◽  
Foundation Design ◽  
Advantages And Disadvantages ◽  
Local Shear ◽  
Failure Conditions

<p>The success of any civil engineering structure's foundation design depends upon the accuracy of estimation of soil’s ultimate bearing capacity. Numerous numerical approaches have been proposed to estimate the foundation's bearing capacity value to avoid repetitive and expensive experimental work. All these models have their advantages and disadvantages. In this study, we compiled all the governing equations mentioned in Bureau of Indian standard IS:6403-1981 and modify the equation for Ultimate Bearing Capacity. The equation was modified by considering two new parameters, K1(for general shear) and K2 (for local shear) so that a common governing equation can be used for both general and local shear failure criteria. The program used for running the model was written in MATLAB language code and verified with the observed field data. Results indicate that the proposed model accurately characterized the ultimate, safe, and allowable bearing capacity of a shallow footing at different depths. The correlation coefficients between the observed and model-predicted bearing capacity values for a 2m foundation depth with footing size of 1.5 ×1.5, 2.0 × 2.0, and 2.5 × 2.5 m are 0.95, 0.94, and 0.96. A similar result was noted for the other foundation depth and footing size. Findings show that the model can be used as a reliable tool for predicting the bearing capacity of shallow foundations at any given depth.  Moreover, the formulated model can also be used for the transition zone between general and local shear failure conditions.</p>

scholarly journals TECHNICAL CONDITION OF CORRUGATED METAL TRANSPORT STRUCTURES

2021 ◽  
pp. 38-50
Author(s):  
J. J. LUCHKO ◽  
V. V. KOVALCHUK
Keyword(s):  
Bearing Capacity ◽  
Technical Condition ◽  
The Body ◽  
Soil Environment ◽  
Metal Structures ◽  
Advantages And Disadvantages ◽  
Methods Of Calculation ◽  
Analysis And Synthesis ◽  
The Impact ◽  
Corrugated Metal

Purpose. The purpose of the work is to establish the real technical condition of transport structures made of corrugated metal structures on the basis of the analysis of scientific and technical sources.And to analyze the experience of operation of metal corrugated structures in the soil environment and to form and generalize the problems of ensuring the reliability and durability of structures made of metal corrugated structures in the conditions of operation on railways and highways of Ukraine. Methodology. To achieve this goal, a review of scientific and technical sources and regulations of different countries on the technical condition of transport facilities in Ukraine was conducted. In particular, data on the distribution of bridges and pipes made of corrugated metal structures by mode of transport are given. It is shown that the development and implementation of new technologies for the repair of existing defective pipes and small bridges, both on the railways and highways of Ukraine is a very important issue. A thorough analysis of the experience of operation of corrugated metal structures in the soil environment in different countries was conducted. Data on the main inadmissible defects of pipes and the reasons of their development are given. CMS' (corrugated metal structures) corrosion and other defects are given. A number of examples of overpass defects, collapse of bridges and structures with MCS in operation are presented. The qualitative indicators of metal corrugated structures, their advantages and disadvantages are also considered, the problems and the analysis of ensuring the reliability and durability of the structures with CMS in the conditions of operation on the railways and highways of Ukraine are formulated. Findings. An analysis of domestic and foreign scientific and technical sources on the technical condition of transport facilities in Ukraine was conducted. In particular, the experience of operation of corrugated metal structures in different countries of the world is studied and generalized. The analysis and synthesis of problems of ensuring the reliability and durability of buildings with CMS in the conditions of operation on the railways and highways of Ukraine. Originality. As a result of the analysis of the technical condition of transport facilities operated on railways and highways of Ukraine, it was found that about 15 % of transport facilities – small and medium bridges and culverts on Ukrainian railways and about 45 % of transport facilities on Ukrainian roads have unacceptable defects and require immediate repair and replacement. Also, it was established on the basis of research that there are no methods for assessing the load-bearing capacity of transport facilities with CMS in the presence in the body of the embankment of the railway or highway metal corrugated structures with a diameter greater than 6 m. It was determined that standards don't include regulations on design and monitoring of CMS on railway tracks. Practical value. On the basis of these data it was possible to offer directions of theoretical and experimental research and methods of calculation, tests of CMS and diagnostics of a technical condition of transport structures with CMS. In particular, the measurement of the impact of the environment on the bearing capacity of the CMS and the measurement of residual deformations of the corrugated metal pipe on the railway track. Execution of the analysis and synthesis of methods of calculation of transport constructions with CMS will lead to improvement of methods of calculation of CMS.

scholarly journals Designs of new operating copper processing plants: process types, equipment selection, industry trends

2021 ◽  
pp. 44-52
Author(s):  
V. F. Baranov
Keyword(s):  
Large Scale ◽  
High Capacity ◽  
Process Intensification ◽  
Processing Plant ◽  
Advantages And Disadvantages ◽  
Sulphide Ores ◽  
Flotation Cells ◽  
Ore Preparation ◽  
Processing Plants ◽  
Technical Solutions

The article describes the largest operating processing plants for lowgrade copper sulphide ores of our time: 10 plants using the semi-autogenous grinding (SAG) technology and 10 plants using high-pressure grinding rolls (HPGR), with the output of 18 to 100 Mtpa. The unfavorable natural and economic factors are balanced by improved ore preparation and concentration technologies and high-capacity equipment units, combined with cost-saving layout solutions. The ore preparation sector is currently divided between the competing technologies of semi-autogenous grinding and HPGR. The article contains an overview of their advantages and disadvantages. The world’s largest monosection with the capacity of 55.5 Mtpa, that uses the SAG technology, is described. The role of the Drop Weght Test JKSimMet (A×b) parameter in the selection of the ore preparation method and the trend for using HPGR in the processing of strong ores are shown. Examples are provided for the consequences of an inadequate assessment of the feed strength in SAG-based plant designs. Examples of ore preparation process intensification through the use of HPGR in semi-autogenous grinding circuits are also given. The volume of impeller flotation cells installed has reached 600 m3. An overview of the two largest processing plants of our time with the output of 88 and 100 Mtpa of ore is presented. The innovative technical solutions of a newest low-capacity copper plant are highlighted. Based on the results of the overview, a future processing plant is predicted to use ∅12.8–13 m SAG mills, HPGRs with the roll diameter of 3 m, vertical VTM-7000 mills in ore grinding cycles, large fine screens, large-scale impeller flotation cells, and staged SFR and DFR flotation reactors.

scholarly journals Corrosion protection of reinforcing steel reinforced concrete structures of transport structures

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Alexander Bulkov ◽  
Michail Baev ◽  
Igor Ovchinnikov
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Protection ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
High Strength ◽  
Curing Temperature ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Steel Reinforced Concrete ◽  
Advantages And Disadvantages

The influence of reinforcing steel corrosion on the durability of reinforced concrete structures of transport structures and the degree of knowledge of this problem is considered. It is specified that the protection of reinforcing steel from corrosion is not able to completely replace the correct design and use of high-strength concrete. But it is able to extend the life of reinforced concrete structures. It is noted that corrosion of the reinforcement leads to a decrease in the structural strength due to wear and tear and by a third of the period of operation of reinforced concrete structures, as a result of which transport structures collapse. As an example of the detrimental effect of corrosion of reinforcing steel on the durability of transport structures, examples of accidents of bridges and overpasses caused by this type of corrosion are given. As a result, a conclusion is drawn on the advisability of ensuring a sufficient level of corrosion protection of reinforcing steel to achieve the required durability of reinforced concrete structures of transport structures. The types and causes of corrosion processes in reinforcing steel reinforced concrete structures are described. The compositions and technologies of anticorrosive protection are examined and analyzed. Comparison of the compositions of anticorrosive protection of reinforced concrete structures is carried out according to the following criteria: consumption, density, viability, curing temperature and the number of components of the composition. A comparison of anti-corrosion protection technologies is carried out on the basis of the following indicators: line dimensions, productivity and consumption of energy resources. A comparison is also made of the cost of using various anti-corrosion protection technologies. Based on the data obtained, the advantages and disadvantages of the considered compositions and technologies of corrosion protection are determined. As a result, the most effective and technologically advanced method of corrosion protection of steel reinforcement of reinforced concrete structures of transport structures is selected.

The Eskimo Point water supply program

1979 ◽  
Vol 6 (3) ◽  
pp. 413-422
Author(s):  
R. R. Foster ◽  
T. J. Parent ◽  
R. A. Sorokowski
Keyword(s):  
Water Supply ◽  
Labour Force ◽  
Protective Layer ◽  
Alternative Methods ◽  
Hudson Bay ◽  
Field Investigations ◽  
Local Labour ◽  
Term Delivery ◽  
Cutting Operation ◽  
Earth Fill

Eskimo Point, Northwest Territories, is a predominantly Inuit community of about 900 people, located on the west shore of Hudson Bay. Formerly, its water supply was obtained from nearby small, sometimes polluted, shallow lakes, which freeze to the bottom in winter, necessitating an ice-cutting operation. In 1973, a study was undertaken to investigate alternative methods of improving Eskimo Point's water supply. The recommended solution was the construction of a 6 500 000 gal (29 548 350 L) earth fill reservoir, lined with a hypalon membrane.Further field investigations and detailed design of the facility were carried out in 1974. All long-term delivery items were pre-ordered, and a general contractor was selected through public tender. Utilization of local manpower and equipment was specified.Construction commenced in mid-June of 1975 with the contractor providing on-the-job training to local Inuit, who adapted quickly to the equipment. Within 2 weeks, an all-local labour force was working around the clock constructing the reservoir embankments. Placement of a membrane liner of approximately 3.5 acres (1.4 ha) took 1 week, and was followed by placement of a protective layer of fill over the liner. Through good cooperation among owner, supplier, contractor, and engineer, the reservoir was completed in the fall of 1975 in time to be filled with water from a lake approximately 1 mi (1.6 km) away.

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