In India, majority of cement produced is of blended variety, with fly ash and blast furnace slag as the mineral admixtures used for blending. Blended cements production reduces clinker production thereby leading to conservation of natural resources and energy and also substantial reduction in the CO2 generation, which is a green house gas. The production of blended cements also leads to utilization of two major industrial wastes, coming from thermal power stations and the integrated steel plants. The application of blended cement in concrete imparts better strength and durability properties to the structure. Keeping these aspects in mind, the presentation illustrates the characteristics of two varieties of blended cements, new to Indian cement industry, namely Portland Limestone Cement (PLC) and Portland High Volume fly Ash Cement (PHFC).
This document provides information on the Benfield process for removing carbon dioxide from gas streams. It discusses key aspects of the process including:
- Absorption of CO2 into a potassium carbonate solution and regeneration of the solution by heating.
- Use of an activator like DEA to improve CO2 absorption.
- Comparison with other CO2 removal processes like Rectisol and considerations for process selection.
- Parameters that affect the absorption and regeneration steps like pressure, temperature, and flow rates.
- Causes and prevention of corrosion in the system through vanadium addition and factors that can cause foaming of the solution.
High volume fly ash concrete is a concrete where a replacement of about 35% or more of cement is made with the usage of fly ash.
Fly ash concrete is an eco-friendly construction material in which fly ash replaces a part of Portland cement.
This is a presentation made by Dr J D Bapat, during his talk on the "Durability of Concrete", on the Foundation Day of Indian Concrete Institute, Pune Centre, India. The presentation includes the role played by the mineral admixtures in imparting the strength and durability to concrete. It also mentions different mechanisms of the deterioration of concrete.
The document discusses high volume fly ash concrete (HVFAC), which uses a 50-60% replacement of cement with fly ash. Fly ash is a byproduct of coal combustion that exhibits pozzolanic behavior. HVFAC provides benefits like lower heat production, improved sulfate and sea water resistance, and higher strength properties compared to normal concrete. The document outlines the production and availability of fly ash, factors affecting fly ash concrete performance like fineness and calcium content, applications of HVFAC in dam and pavement construction, and longer curing requirements.
The document discusses aerodynamics concepts related to blast furnaces including:
- Higher blast rates can increase productivity but also risks irregularities like channeling if bed permeability is not uniform
- Pressure drop in a packed bed reactor is calculated using the Ergun equation and depends on factors like voidage, particle size, gas properties
- Pressure drop increases significantly with decreasing voidage or with mixed vs. layered beds, and is very sensitive to particle size differences
- Minimum gas velocities needed for fluidization depend on temperature, particle properties, and can limit maximum productivity
- Channeling occurs when gas flows through distinct channels due to non-uniform packing, and higher top pressure can help address this
Cement and Concrete: Promise of Fly AshDr J.D. Bapat
The presentation made by Dr J D Bapat illustrates the importance of fly ash utilisation. The slides depict how fly ash is used in cement and concrete to improve its strength and durability.
The document describes the process of fluidized catalytic cracking (FCC) used in petroleum refineries. It explains that FCC converts high-boiling petroleum fractions into high-value gasoline and heating oil using a zeolite catalyst. The key components of an FCC unit are the reactor, where the reaction occurs, and the regenerator, where the catalyst is regenerated by burning off coke deposits. It then provides details on the operation of each component and the flow of catalyst and feedstock through the system. It also discusses advantages and disadvantages of FCC and presents a case study analyzing catalyst selection for a refinery in Jiddah.
In India, majority of cement produced is of blended variety, with fly ash and blast furnace slag as the mineral admixtures used for blending. Blended cements production reduces clinker production thereby leading to conservation of natural resources and energy and also substantial reduction in the CO2 generation, which is a green house gas. The production of blended cements also leads to utilization of two major industrial wastes, coming from thermal power stations and the integrated steel plants. The application of blended cement in concrete imparts better strength and durability properties to the structure. Keeping these aspects in mind, the presentation illustrates the characteristics of two varieties of blended cements, new to Indian cement industry, namely Portland Limestone Cement (PLC) and Portland High Volume fly Ash Cement (PHFC).
This document provides information on the Benfield process for removing carbon dioxide from gas streams. It discusses key aspects of the process including:
- Absorption of CO2 into a potassium carbonate solution and regeneration of the solution by heating.
- Use of an activator like DEA to improve CO2 absorption.
- Comparison with other CO2 removal processes like Rectisol and considerations for process selection.
- Parameters that affect the absorption and regeneration steps like pressure, temperature, and flow rates.
- Causes and prevention of corrosion in the system through vanadium addition and factors that can cause foaming of the solution.
High volume fly ash concrete is a concrete where a replacement of about 35% or more of cement is made with the usage of fly ash.
Fly ash concrete is an eco-friendly construction material in which fly ash replaces a part of Portland cement.
This is a presentation made by Dr J D Bapat, during his talk on the "Durability of Concrete", on the Foundation Day of Indian Concrete Institute, Pune Centre, India. The presentation includes the role played by the mineral admixtures in imparting the strength and durability to concrete. It also mentions different mechanisms of the deterioration of concrete.
The document discusses high volume fly ash concrete (HVFAC), which uses a 50-60% replacement of cement with fly ash. Fly ash is a byproduct of coal combustion that exhibits pozzolanic behavior. HVFAC provides benefits like lower heat production, improved sulfate and sea water resistance, and higher strength properties compared to normal concrete. The document outlines the production and availability of fly ash, factors affecting fly ash concrete performance like fineness and calcium content, applications of HVFAC in dam and pavement construction, and longer curing requirements.
The document discusses aerodynamics concepts related to blast furnaces including:
- Higher blast rates can increase productivity but also risks irregularities like channeling if bed permeability is not uniform
- Pressure drop in a packed bed reactor is calculated using the Ergun equation and depends on factors like voidage, particle size, gas properties
- Pressure drop increases significantly with decreasing voidage or with mixed vs. layered beds, and is very sensitive to particle size differences
- Minimum gas velocities needed for fluidization depend on temperature, particle properties, and can limit maximum productivity
- Channeling occurs when gas flows through distinct channels due to non-uniform packing, and higher top pressure can help address this
Cement and Concrete: Promise of Fly AshDr J.D. Bapat
The presentation made by Dr J D Bapat illustrates the importance of fly ash utilisation. The slides depict how fly ash is used in cement and concrete to improve its strength and durability.
The document describes the process of fluidized catalytic cracking (FCC) used in petroleum refineries. It explains that FCC converts high-boiling petroleum fractions into high-value gasoline and heating oil using a zeolite catalyst. The key components of an FCC unit are the reactor, where the reaction occurs, and the regenerator, where the catalyst is regenerated by burning off coke deposits. It then provides details on the operation of each component and the flow of catalyst and feedstock through the system. It also discusses advantages and disadvantages of FCC and presents a case study analyzing catalyst selection for a refinery in Jiddah.
Four main low-carbon technologies for cement production are presented, namely (a) alternative fuels (AF) for kiln, (b) renewable energy alternatives, (c) increasing cement replacement by fly ash and blast furnace slag and (d) Portland limestone cement.
This document discusses considerations for firing petcoke in kilns. It notes that petcoke has higher sulfur content than coal which can increase build-ups in the kiln system. It also has lower volatiles and ash. The document provides rules for utilizing petcoke, including maintaining appropriate alkali to sulfur ratios and ensuring proper coal and petcoke preparation and feeding. It discusses grinding petcoke to a finer particle size. Combustion considerations include maintaining sufficient oxygen levels. Refractory failures can result from high temperatures or sulfur/alkali effects from burning petcoke. Denser or zircon-added refractories may improve resistance.
This document discusses considerations for firing petcoke in kilns. It notes that petcoke has higher sulfur content than coal which can increase build-ups in the kiln system. It also has lower volatiles and ash. The document provides rules for utilizing petcoke, including maintaining appropriate alkali to sulfur ratios and ensuring proper coal and petcoke preparation and feeding. It discusses grinding petcoke to a finer particle size. Combustion considerations include maintaining sufficient oxygen levels. Refractory failures can result from high temperatures or sulfur/alkali effects from burning petcoke. Denser refractories with additions like zircon or AZS castables can improve buildup resistance.
Coal Ashes In Geo-technical Engineering Practice-Beneficial AspectsSandeep Jaiswal
This document discusses the beneficial aspects of using coal ashes in geotechnical engineering. It begins by providing background on the large worldwide production of coal ashes as a byproduct of coal-burning power plants. It then outlines various applications of coal ashes from high to low value uses. The document focuses on the beneficial geotechnical properties of coal ashes, including their low specific gravity, good compaction characteristics, high shear strength and angle of internal friction, high California Bearing Ratio, low compressibility, and use in soil stabilization. It concludes that coal ashes have several properties making them useful as fill materials, construction fills, retaining wall backfill, foundations, and soil admixtures.
The document summarizes two experimental studies on improving the durability of concrete bridge decks. Phase I studied different concrete mix designs including ordinary Portland cement and mixes with admixtures like fly ash and blast furnace slag. Phase II focused on three mix designs: ordinary Portland cement and two high-performance concretes with different admixture combinations. Field application of the best performing mix from Phase II on an actual bridge deck is also described. Test results showed that high-performance concretes improved cracking resistance, chloride permeability, scaling resistance and freeze-thaw durability compared to ordinary Portland cement.
This document summarizes research on developing a phosphoric acid doped poly(2,5-benzimidazole) membrane for use in high temperature fuel cells. Key points:
- Undoped and phosphoric acid doped poly(2,5-benzimidazole) membranes were prepared using a solvent casting method. Phosphoric acid concentration was varied from 0-60% by volume to improve proton conductivity at high temperatures.
- The 60% phosphoric acid doped membrane with a doping level of 1.65 showed the highest proton conductivity of 2.2 x 10-2 S/cm. It exhibited a decrease in crystallinity and mechanical properties compared to the undoped membrane.
Unit lightup synchronisation & shutdownAshvani Shukla
India's first 660 MW supercritical unit was synchronized by Adani Power Ltd in Mundra in 2010 in just 36 months. This document outlines the startup and shutdown sequence for supercritical units, including boiler flushing, turbine lining up, rolling, loading procedures, and phase changes from wet to dry and wet to supercritical modes. Key steps include boiler flushing to reduce iron and silica levels, preheating the high pressure casing, turbine rolling to operating speed, and gradually increasing load while bringing systems online.
Competitive clean coal power utilizing pressurized fluidized bed combined cyc...aoopee
PFBC technology utilizes a pressurized fluidized bed combined-cycle process to cleanly and efficiently generate power from coal. This process results in higher thermal efficiencies than conventional steam plants, with future efficiencies forecast above 50%. It can utilize all coal types, including difficult coals, in an environmentally acceptable manner by reducing emissions. The modular design of the PFBC system makes it suitable for both new installations and repowering existing plants.
Far East Energy - Corporate Presentation January 2014Company Spotlight
Far East Energy Corporation is a leading developer of coalbed methane resources in China. The company's large block in Shouyang has high permeability and gas content, making it one of the few large CBM blocks in China with this important characteristic. The block has over 440 Bcf of net proved and probable reserves and a post-tax NPV of over $2 billion based on a long term gas sales contract with favorable pricing. The block benefits from excellent infrastructure including multiple pipelines and markets with over 325 MMcf/d of potential offtake capacity, positioning Far East Energy for strong production and cash flow growth.
This document discusses the use of carbon dioxide (CO2) as an alternative refrigerant to halogenated gases. It summarizes that CO2 offers unique design challenges, especially in selecting seal materials that can withstand the extreme temperature range of -40 to +160°C involved in the CO2 refrigeration cycle. The document evaluates different seal material options and notes that fluorocarbon, hydrogenated nitrile, and ethylene-propylene compounds have the best thermal stability. It also discusses challenges related to chemical compatibility between CO2, compressor oils and rubber seals, as well as high operating pressures of CO2 refrigeration cycles.
A resposta dos metais aos desafios do projeto automotivo 2Agencia G ABC
The document compares the properties of traditional gray iron, HPI alloy, and CGI alloy. HPI alloy has higher tensile strength (300-370 MPa) and thermal conductivity than gray iron, but lower vibration damping. Compared to CGI, HPI has similar tensile strength but lower thermal conductivity and vibration damping. HPI aims to optimize properties by controlling eutectic solidification and the ratios of manganese, sulfur, and silicon to achieve a stable eutectic temperature range.
The document discusses partial gasification of pre-dried pulverized coal through waste heat recovery as a future clean coal technology option. It notes that coal pulverizing is an energy intensive process dependent on coal properties. Improving pulverizer performance is limited by design and tied to drying low rank coals with high moisture content. The document proposes using waste heat from flue gases to partially dry coal prior to pulverizing, which could improve mill throughput and reduce boiler heat rate penalties from coal drying. Field studies showed this partial flue gas recirculation approach enabled higher mill capacity and steam generation compared to without waste heat recovery.
Fly ash is the residue from burning pulverized coal in power plants. There are two main types of fly ash: Type C contains more than 10% calcium oxide and has both pozzolanic and cementitious properties, while Type F contains less than 10% calcium oxide and only has pozzolanic properties. The addition of fly ash to concrete can affect its properties in several ways - it requires slightly more water, may decrease early strength, reduces permeability and heat of hydration, and increases setting time. Fly ash can also improve resistance to sulfate attack and reduce shrinkage, depending on the fineness and carbon content.
The document provides tips for improving energy efficiency in boilers, steam systems, chillers, insulation, motors, and compressed air. Some key points include: a 22 degree reduction in flue gas temperature or 5% reduction in excess air can increase boiler efficiency by 1%; a 3mm thick soot deposition can increase fuel consumption by 2.5%; and reducing compressed air leakage rates by 10% through a 1 kg/cm2 reduction in air pressure can result in 9% input power savings.
Effect of Annealing on Erosion Behavior of Atmospheric Plasma Spray and High ...IRJET Journal
This document summarizes a study on the effect of annealing on the erosion behavior of tungsten carbide-chromium carbide-nickel coatings applied via atmospheric plasma spray (APS) and high-velocity oxy-fuel spray (HVOF). Samples were annealed at 550 degrees Celsius and tested for erosion resistance at 450-575 degrees using alumina powder. Results showed that both coatings exhibited improved hardness after annealing, with HVOF showing greater hardness gains and wear resistance than APS. HVOF coatings also demonstrated superior erosion performance compared to APS coatings and uncoated steel substrates across all test conditions due to retaining a higher percentage of hard carbides at elevated temperatures.
Presented by Chris Saigbe at the 4th Annual East Africa Finance Summit
Africa and indeed Ethiopia have the potentials to grow their Life Insurance Industries.
Growth is continuous because there are new opportunities and
possibilities to build on the progress already made
Presented by Getahun Nana at the 4th Annual East Africa Finance Summit
Modernization of Ethiopian payment system needs disruptive changes
Digitization offers disruptive and a transformative solution to modernization of payment systems
Presented by Shaun Bennet at the 4th Annual East Africa Finance Summit
Single master data record of client
Unique client reference
Easy management of client references
Ability to match similar record on a continuous basis
Four main low-carbon technologies for cement production are presented, namely (a) alternative fuels (AF) for kiln, (b) renewable energy alternatives, (c) increasing cement replacement by fly ash and blast furnace slag and (d) Portland limestone cement.
This document discusses considerations for firing petcoke in kilns. It notes that petcoke has higher sulfur content than coal which can increase build-ups in the kiln system. It also has lower volatiles and ash. The document provides rules for utilizing petcoke, including maintaining appropriate alkali to sulfur ratios and ensuring proper coal and petcoke preparation and feeding. It discusses grinding petcoke to a finer particle size. Combustion considerations include maintaining sufficient oxygen levels. Refractory failures can result from high temperatures or sulfur/alkali effects from burning petcoke. Denser or zircon-added refractories may improve resistance.
This document discusses considerations for firing petcoke in kilns. It notes that petcoke has higher sulfur content than coal which can increase build-ups in the kiln system. It also has lower volatiles and ash. The document provides rules for utilizing petcoke, including maintaining appropriate alkali to sulfur ratios and ensuring proper coal and petcoke preparation and feeding. It discusses grinding petcoke to a finer particle size. Combustion considerations include maintaining sufficient oxygen levels. Refractory failures can result from high temperatures or sulfur/alkali effects from burning petcoke. Denser refractories with additions like zircon or AZS castables can improve buildup resistance.
Coal Ashes In Geo-technical Engineering Practice-Beneficial AspectsSandeep Jaiswal
This document discusses the beneficial aspects of using coal ashes in geotechnical engineering. It begins by providing background on the large worldwide production of coal ashes as a byproduct of coal-burning power plants. It then outlines various applications of coal ashes from high to low value uses. The document focuses on the beneficial geotechnical properties of coal ashes, including their low specific gravity, good compaction characteristics, high shear strength and angle of internal friction, high California Bearing Ratio, low compressibility, and use in soil stabilization. It concludes that coal ashes have several properties making them useful as fill materials, construction fills, retaining wall backfill, foundations, and soil admixtures.
The document summarizes two experimental studies on improving the durability of concrete bridge decks. Phase I studied different concrete mix designs including ordinary Portland cement and mixes with admixtures like fly ash and blast furnace slag. Phase II focused on three mix designs: ordinary Portland cement and two high-performance concretes with different admixture combinations. Field application of the best performing mix from Phase II on an actual bridge deck is also described. Test results showed that high-performance concretes improved cracking resistance, chloride permeability, scaling resistance and freeze-thaw durability compared to ordinary Portland cement.
This document summarizes research on developing a phosphoric acid doped poly(2,5-benzimidazole) membrane for use in high temperature fuel cells. Key points:
- Undoped and phosphoric acid doped poly(2,5-benzimidazole) membranes were prepared using a solvent casting method. Phosphoric acid concentration was varied from 0-60% by volume to improve proton conductivity at high temperatures.
- The 60% phosphoric acid doped membrane with a doping level of 1.65 showed the highest proton conductivity of 2.2 x 10-2 S/cm. It exhibited a decrease in crystallinity and mechanical properties compared to the undoped membrane.
Unit lightup synchronisation & shutdownAshvani Shukla
India's first 660 MW supercritical unit was synchronized by Adani Power Ltd in Mundra in 2010 in just 36 months. This document outlines the startup and shutdown sequence for supercritical units, including boiler flushing, turbine lining up, rolling, loading procedures, and phase changes from wet to dry and wet to supercritical modes. Key steps include boiler flushing to reduce iron and silica levels, preheating the high pressure casing, turbine rolling to operating speed, and gradually increasing load while bringing systems online.
Competitive clean coal power utilizing pressurized fluidized bed combined cyc...aoopee
PFBC technology utilizes a pressurized fluidized bed combined-cycle process to cleanly and efficiently generate power from coal. This process results in higher thermal efficiencies than conventional steam plants, with future efficiencies forecast above 50%. It can utilize all coal types, including difficult coals, in an environmentally acceptable manner by reducing emissions. The modular design of the PFBC system makes it suitable for both new installations and repowering existing plants.
Far East Energy - Corporate Presentation January 2014Company Spotlight
Far East Energy Corporation is a leading developer of coalbed methane resources in China. The company's large block in Shouyang has high permeability and gas content, making it one of the few large CBM blocks in China with this important characteristic. The block has over 440 Bcf of net proved and probable reserves and a post-tax NPV of over $2 billion based on a long term gas sales contract with favorable pricing. The block benefits from excellent infrastructure including multiple pipelines and markets with over 325 MMcf/d of potential offtake capacity, positioning Far East Energy for strong production and cash flow growth.
This document discusses the use of carbon dioxide (CO2) as an alternative refrigerant to halogenated gases. It summarizes that CO2 offers unique design challenges, especially in selecting seal materials that can withstand the extreme temperature range of -40 to +160°C involved in the CO2 refrigeration cycle. The document evaluates different seal material options and notes that fluorocarbon, hydrogenated nitrile, and ethylene-propylene compounds have the best thermal stability. It also discusses challenges related to chemical compatibility between CO2, compressor oils and rubber seals, as well as high operating pressures of CO2 refrigeration cycles.
A resposta dos metais aos desafios do projeto automotivo 2Agencia G ABC
The document compares the properties of traditional gray iron, HPI alloy, and CGI alloy. HPI alloy has higher tensile strength (300-370 MPa) and thermal conductivity than gray iron, but lower vibration damping. Compared to CGI, HPI has similar tensile strength but lower thermal conductivity and vibration damping. HPI aims to optimize properties by controlling eutectic solidification and the ratios of manganese, sulfur, and silicon to achieve a stable eutectic temperature range.
The document discusses partial gasification of pre-dried pulverized coal through waste heat recovery as a future clean coal technology option. It notes that coal pulverizing is an energy intensive process dependent on coal properties. Improving pulverizer performance is limited by design and tied to drying low rank coals with high moisture content. The document proposes using waste heat from flue gases to partially dry coal prior to pulverizing, which could improve mill throughput and reduce boiler heat rate penalties from coal drying. Field studies showed this partial flue gas recirculation approach enabled higher mill capacity and steam generation compared to without waste heat recovery.
Fly ash is the residue from burning pulverized coal in power plants. There are two main types of fly ash: Type C contains more than 10% calcium oxide and has both pozzolanic and cementitious properties, while Type F contains less than 10% calcium oxide and only has pozzolanic properties. The addition of fly ash to concrete can affect its properties in several ways - it requires slightly more water, may decrease early strength, reduces permeability and heat of hydration, and increases setting time. Fly ash can also improve resistance to sulfate attack and reduce shrinkage, depending on the fineness and carbon content.
The document provides tips for improving energy efficiency in boilers, steam systems, chillers, insulation, motors, and compressed air. Some key points include: a 22 degree reduction in flue gas temperature or 5% reduction in excess air can increase boiler efficiency by 1%; a 3mm thick soot deposition can increase fuel consumption by 2.5%; and reducing compressed air leakage rates by 10% through a 1 kg/cm2 reduction in air pressure can result in 9% input power savings.
Effect of Annealing on Erosion Behavior of Atmospheric Plasma Spray and High ...IRJET Journal
This document summarizes a study on the effect of annealing on the erosion behavior of tungsten carbide-chromium carbide-nickel coatings applied via atmospheric plasma spray (APS) and high-velocity oxy-fuel spray (HVOF). Samples were annealed at 550 degrees Celsius and tested for erosion resistance at 450-575 degrees using alumina powder. Results showed that both coatings exhibited improved hardness after annealing, with HVOF showing greater hardness gains and wear resistance than APS. HVOF coatings also demonstrated superior erosion performance compared to APS coatings and uncoated steel substrates across all test conditions due to retaining a higher percentage of hard carbides at elevated temperatures.
Similar to Dr. Jayant D. Bapat - Durable and Sustainable Concrete with Mineral Admixtures, 3rd EACCES (18)
Presented by Chris Saigbe at the 4th Annual East Africa Finance Summit
Africa and indeed Ethiopia have the potentials to grow their Life Insurance Industries.
Growth is continuous because there are new opportunities and
possibilities to build on the progress already made
Presented by Getahun Nana at the 4th Annual East Africa Finance Summit
Modernization of Ethiopian payment system needs disruptive changes
Digitization offers disruptive and a transformative solution to modernization of payment systems
Presented by Shaun Bennet at the 4th Annual East Africa Finance Summit
Single master data record of client
Unique client reference
Easy management of client references
Ability to match similar record on a continuous basis
1) The ECX operates as a marketplace that brings together buyers and sellers of commodities in Ethiopia. It provides services like grading, warehousing, trading, clearing and settlement, and market information.
2) The ECX has an institutional arrangement as a non-profit company established by law to operate autonomously. It is jointly governed by the government and private members through a board of directors.
3) The ECX has various market infrastructures to facilitate trading, including an electronic trading platform, clearing house, central depository system, and tools to disseminate market data and information.
Presented by Dr. Nissar Ahmed Yatoo at the 4th Annual East Africa Finance Summit
1.Interest Free Transactions
2.Sharing of associated risks and profits
3.No scope for uncertainty
4.Emphasis on Ethical Investment
5.Tangible and identifiable underlying assets to back-up financial transactions
Presented by Jerry Sogoli at the 4th Annual East Africa Finance Summit
A comparative analysis of the independent regulatory agency approach vis-à-vis direct government oversight and the appropriateness of the former in regulating today’s insurance sector
Present by Caesar Baulona at the 4th Annual East Africa Finance Summit
How do we effectively sort incoming claims so that we most efficiently allocate resources to obtain additional information at a cost?
Presented by Melesse Minale at the 4th Annual East Africa Finance Summit.
Access to finance is one of the main bottlenecks to business and financial inclusion is very low
Presentation by Boniface Mungania at the 4th Annual East Africa Finance Summit
How digital platforms can catalyze access and more inclusive communities in Ethiopia and beyond
The document discusses capital market development in East Africa under the Homegrown Economic Reform Program (HERP). It outlines two phases of reform: developing a competitive treasury bills market and establishing a stock exchange. For phase one, the necessary legal and regulatory frameworks for treasury bill auctions are in place and the first competitive auction was conducted. For phase two, preliminary assessments show the need to develop legal/regulatory frameworks and market infrastructure like a registry before establishing a stock exchange. Capacity building efforts are ongoing for both the central bank and private sector.
This document contains summaries of various training seminars offered in 2019. The seminars cover topics such as social media engagement strategies, competency management, customer centricity, presentation skills, change management, and performance management. The target groups for the seminars include executives, directors, managers, experts, and staff.
This is a presentation by Yodahe A. Zemichael, Principal Technical Advisor, Office of the Ethiopian Prime Minister, at the 3rd Annual East Africa FInance Summit
This is a presentation by Paschal Anosike, Director, Centre for African Entrepreneurship and Leadership (CAEL), University of Wolverhampton, UK, at the 3rd Annual East Africa Finance Summit
The document discusses the insurance sector in Ethiopia, including its history and current state. It analyzes the prospects and challenges of liberalizing the insurance sector in Ethiopia. Some key points:
- Ethiopia's insurance sector has historically been closed to foreign participation and remains less developed than neighboring countries. The sector is highly concentrated among a few large insurers.
- Liberalizing the sector could boost competition but faces challenges like weak insurers, low public awareness, and lack of data. Comparisons show Ethiopia's insurance penetration and density are much lower than global and regional averages.
- The performance of private insurers is generally better than the state-owned insurer. However, insurers remain focused on traditional
1) Ethiopia has high potential for e-commerce growth given its large population and rapid infrastructure development, but card-not-present transactions present security risks.
2) 3D Secure is a global standard that adds an extra authentication layer for online payments, reducing fraud liability for merchants. It works by requesting additional identity verification from the cardholder during checkout.
3) While 3D Secure reduces fraud, some countries still experience high costs of billions from card-not-present fraud each year, showing the ongoing need to implement secure online payment solutions.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
Low power architecture of logic gates using adiabatic techniquesnooriasukmaningtyas
The growing significance of portable systems to limit power consumption in ultra-large-scale-integration chips of very high density, has recently led to rapid and inventive progresses in low-power design. The most effective technique is adiabatic logic circuit design in energy-efficient hardware. This paper presents two adiabatic approaches for the design of low power circuits, modified positive feedback adiabatic logic (modified PFAL) and the other is direct current diode based positive feedback adiabatic logic (DC-DB PFAL). Logic gates are the preliminary components in any digital circuit design. By improving the performance of basic gates, one can improvise the whole system performance. In this paper proposed circuit design of the low power architecture of OR/NOR, AND/NAND, and XOR/XNOR gates are presented using the said approaches and their results are analyzed for powerdissipation, delay, power-delay-product and rise time and compared with the other adiabatic techniques along with the conventional complementary metal oxide semiconductor (CMOS) designs reported in the literature. It has been found that the designs with DC-DB PFAL technique outperform with the percentage improvement of 65% for NOR gate and 7% for NAND gate and 34% for XNOR gate over the modified PFAL techniques at 10 MHz respectively.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Dr. Jayant D. Bapat - Durable and Sustainable Concrete with Mineral Admixtures, 3rd EACCES
1. DURABLE & SUSTAINABLE CONCRETE
WITH
MINERAL ADMIXTURES
by
Dr J D Bapat
http://www.drjdbapat.com
3rd EAST AFRICA CEMENT, CONCRETE
AND ENERGY SUMMIT
ADDIS ABABA
1-2 AUGUST 2018
2. ACKNOWLEDGEMENT
• WITH SINCERE THANKS TO THE PUBLISHER:
• I ACKNOWLEDGE THAT WHILE PREPARING THIS
PRESENTATION I HAVE USED INFORMATION GIVEN IN MY
BOOK:
“MINERAL ADMIXTURES IN CEMENT AND CONCRETE”
CRC PRESS – TAYLOR & FRANCIS GROUP
5. PULVERISED FUEL ASH
ENERGY & GHG
CEMENT TYPE THERMAL ENERGY ELECTRICAL ENERGY
PC 100 100
PPC (15%) 84 89
PSC (50%) 47 79
• IDEAL ENERGY CONSUMPTION FOR A NEW LARGE CAPACITY PLANT:
THERMAL: 680–720 kcal/kg & ELECTRICAL: 72–74 kwh/t
• CEMENT INDUSTRY CONTRIBUTES 5% OF TOTAL ANTHROPOGENIC CO2
EMISSIONS GLOBALLY
• WBCSD TARGET: REDUCTION IN CO2 EMISSION BY A FACTOR OF 2 BY 2050
FROM THEIR 1990 LEVELS
• TECHNOLOGICAL SHIFT: CHANGES IN CONCRETE RAW MATERIALS, MIX
DESIGN, NEW BUILDING TECHNIQUES & USING LESS MATERIALS
6. PULVERISED FUEL ASH (PFA)
PULVERISED FUEL ASH OR FLY ASH IS
INORGANIC MATTER LEFT AFTER COAL
COMBUSTION, WHICH GETS COLLECTED, IN FINE
FORM, IN ELECTROSTATIC PRECIPITATORS (ESP)
OF THERMAL POWER STATIONS
ADDITION OF PFA TO CEMENT OR CONCRETE
REDUCES CLINKER PRODUCTION & CONTRIBUTES
TO LONG TERM STRENGTH & DURABILITY OF
CONCRETE
7. PULVERISED FUEL ASH
PHYSICAL
ASTM C618 CLASSIFICATION:
CLASS F: OBTAINED BY BURNING ANTHRACITE COAL: POZZOLANIC
CLASS C: OBTAINED BY BURNING LIGNITE COAL: POZZOLANIC &
CEMENTITIOUS
PHYSICAL CHARACTERISTICS: NAMELY, SHAPE, SPECIFIC GRAVITY,
SIZE AND FINENESS, & UNBURNED CARBON CONTENT, AFFECT PFA
PERFORMANCE IN CONCRETE
POZZOLANIC REACTIVITY: AFFECTED BY FINENESS THAN GLASS
CONTENT (.) GRINDING OR SIZE REDUCTION OPERATION IMPROVES
POZZOLANIC ACTIVITY OF PFA
12. PULVERISED FUEL ASH
PHYSICAL
PARTICLE SIZE RANGE: 1 TO 100 MICRON
UNDER 10 MICRON: EARLY, 7 & 28 D, STRENGTH
10 TO 45 MICRON: REACT SLOWLY & CONTRIBUTE TOWARD LATE
STRENGTH , UP TO 1 YEAR
ABOVE 45 MICRON: INERT & ACT AS FINE SAND OR FILLER
UNBURNED CARBON (UBC) PARTICLES:
CONTRIBUTE MAX TO LOSS ON IGNITION
INFLUENCE CEMENT WATER DEMAND FOR STANDARD
CONSISTENCY
STRONG AFFINITY TOWARD ORGANIC CHEMICAL ADMIXTURES,
SUCH AS AIR-ENTRAINING AGENTS (AEA)
PFA WITH LESS THAN 3%–4% CARBON: SAFE TO USE
13. PULVERISED FUEL ASH
CHEMICAL & MINERALOGICAL
HETEROGENEOUS MIXTURE OF COMPLEX
ALUMINOSILICATE GLASSES & SOME CRYSTALLINE
CONSTITUENTS
OXIDE COMPOSITION OF PFA EXHIBITS SUBSTANTIAL
REGIONAL VARIATION
PFA COMING FROM SAME SOURCE (NAMELY, THERMAL
POWER STATION) MAY ALSO SHOW VARIATION IN
COMPOSITION
14. PULVERISED FUEL ASH
CHEMICAL & MINERALOGICAL
IN PORTLAND CEMENT THERE IS CLOSE RELATIONSHIP
BETWEEN CHEMICAL & MINERALOGICAL COMPOSITION
IN MINERAL ADMIXTURE THERE IS NO RELATIONSHIP
BETWEEN CHEMICAL & MINERALOGICAL COMPOSITION
15. PULVERISED FUEL ASH
FLUIDISED BED
LOW TEMP: IN COMPARISON TO CONVENTIONAL
PULVERIZED COAL FIRED SYSTEM, FLUIDISED BED SYSTEM
HAS A RELATIVELY LOW COMBUSTION TEMPERATURE,
TYPICALLY IN RANGE 800°C–900°C
NON-ASTM: PFA FROM FLUIDISED BED CANNOT BE
CLASSIFIED AS ASTM CLASS F OR C, IN MANY CASES,
BECAUSE OF LOW FAS (FERRIC OXIDE + ALUMINA + SILICA
CONTENT) & HIGH SO3 CONTENT
16. PULVERISED FUEL ASH
CO-COMBUSTION
PFA FROM CO-COMBUSTION OF BITUMINOUS COAL &
PETCOKE
ADDS MORE UBC & COARSENESS TO PFA
NO LEACHING OF NICKEL & VANADIUM IN ENVIRONMENT
USE OF PETCOKE PFA HAS NO DETRIMENTAL EFFECTS ON
EITHER STRENGTH DEVELOPMENT OR AIR ENTRAINMENT
COMPARED TO BITUMINOUS COAL PFA
17. PULVERISED FUEL ASH
ULTRA FINE FA OR UFFA
ULTRA-FINE FA
MEAN PARTICLE DIA OF CONVENTIONAL FA: 5-30 MICRONS
MEAN PARTICLE DIA OF ULTRA-FINE FA : 1-5 MICRONS
LOW UNBURNED CARBON
18. PULVERISED FUEL ASH
UFFA REMOVES FA LIMITATIONS
HIGHER EARLY STRENGTH & HIGHER HEAT OF HYDARTION
DUE TO FASTER & COMPLETE REACTION
LOW REPLACEMENT: 5-15% REPLACEMENT UFFA MAKES
SUBSTANTIAL CONTRIBUTION TO CONCRETE STRENGTH &
PERMEABILITY REDUCTION
BETTER DURABILITY: WITH LESS CARBON & FINER
PARTICLES REACTING COMPLETELY
CONCRETE DURABILITY PROPERTIES LIKE RESISTANCE TO
ALKALI-AGGREGATE REACTION, SULFATE ATTACK,
CORROSION ARE ENHANCED BY UFFA
19. PULVERISED FUEL ASH
SPECIFYING FOR CONCRETE
LARGER QUANTITIES OF FA (>25) DELAY SETTING & EARLY
STRENGTH, BUT CAN BE TACKLED EFFECTIVELY WITH SP
LOI: 2-4% DOES NOT ALWAYS ELIMINATE PROBLEM OF AIR
ENTRAINING AGENT, WHEN CARBON PARTICLES ARE FINE
WHERE POSSIBLE, SPECIFYING 56 DAY STRENGTH INSTEAD OF
28 DAY, CAN RESULT IN BETTER OPTIMISED MIXTURE
FOR REACTIVE AGGREGATES, BETTER TO PERFORM STANDARD
EXPANSION TESTS TO DETERMINE LIMIT OF FA ADDITION
TO CONTROL ASR, BETTER TO KEEP FA ALKALI < 5% Na2O eq.
(IS 3812 SPECIFIES < 1.5%)
20. PULVERISED FUEL ASH
SPECIFYING FOR CONCRETE
CLORIDE RESISTANCE: PERFORM RCPT AS PER ASTM C1202 TO
FIND FA CONTENT FOR RCPT VALUE OF 1500-2000 COULOMBS (.) 56
DAY STRENGTH ADVISABLE
IS 456-2000: MAX ACID SOLUBLE Cl IN RCC = 0.6 Kg/M3
CONCRETE
SULPHATE RESISTANCE: IS 456 SPECIFIES MAX 4% BY MASS OF
CEMENT IN CONCRETE MIX
PERFORM TEST AS PER ASTM C1012 TO FIND OPTIMUM FA FOR
SULPHATE RESISTANCE (.) ONLY DISADVANTAGE IS TEST TAKES
LONG TIME: 6 MONTHS TO 1 YEAR
21. PULVERISED FUEL ASH
ADDITION TO CEMENT & CONCRETE
PFA IS ADDED DIRECTLY TO RMC AT BATCHING UNIT,
INTER-GROUND WITH CEMENT CLINKER, OR BLENDED WITH
PC AT CEMENT PLANT TO PRODUCE BLENDED CEMENT
BLENDED CEMENT: MOST NATIONAL STANDARDS ALLOW
ADDITION OF PFA TO CEMENT UP TO THE EXTENT OF 35%–
40%, TO MANUFACTURE BLENDED CEMENT
23. BLAST FURNACE SLAG (BFS)
GGBS
GROUND GRANULATED BFS OR GGBS
PRODUCED BY QUENCHING OF MOLTEN SLAG COMING FROM
BLAST FURNACE IN PARTICLE SIZE MOSTLY PASSING 4.75 mm
SIEVE & MAX UP TO 10 mm
1 t OF PIG IRON GENERATES 250–350 kg OF SLAG
BRITISH STANDARD SPECIFICATION FOR GGBS (BS 6699), FOR
USE WITH PORTLAND CEMENT, REQUIRES GLASS CONTENT >
67%
GRINDING OF GRANULATED BFS, LEADS TO PRODUCTION OF
GROUND GRANULATED BLAST FURNACE SLAG OR GGBS
24. BLAST FURNACE SLAG (BFS)
GGBS
LOWER SPECIFIC GRAVITY: IN RANGE OF 2.9–3.0, LOWER
IN COMPARISON WITH PC (3.0 - 3.2)
FINENESS & STRENGTH CHARACTERISTICS OF GGBS ARE
CONVENTIONALLY CORRELATED
ACTIVITY OF GGBS IS PROPORTIONAL TO THE GLASS
CONTENT
26. BLAST FURNACE SLAG (BFS)
QUALITY CONTROL
ASTM C-989-09: SPECIFIES THREE GRADES OF GGBS BY
STRENGTH: GRADE 80, 100 & 120
GRADE 120: REPRESENTS HIGHEST STRENGTH
GRADE IS DETERMINED BY STRENGTH OF MORTAR, WHEN GGBS
IS MIXED WITH EQUAL MASS OF PC
THREE GRADES: 80, 100 & 120 CLASSIFIED ACCORDING TO SLAG
ACTIVITY INDEX, BASED ON STRENGTH
SLAG ACTIVITY INDEX (%) = (STRENGTH OF
SLAG+CEMENT)/(STRENGTH OF CEMENT)X100 = (SP/P)100
27. BLAST FURNACE SLAG (BFS)
SPECIFYING FOR CONCRETE
TEMP INFLUENCES SETTING OF GGBS CONCRETE
MASS CONCRETING: TEMP RISE REDUCES WITH INCREASING
GGBS
CARBONISATION: INCREASES WITH GGBS CONTENT BUT
DEPENDS UPON TEMP & RH (.) EFFECTIVELY CONTROLLED
WITH CURING
HIGH RESISTANCE TOWARDS Cl ION PENETRATION DUE TO
ION BINDING CAPACITY
SULPHATE RESISTANCE: INCREASES WITH GGBS > 50%
BETTER RESISTANCE TOWARDS ACID ATTACK
28. BLAST FURNACE SLAG (BFS)
ADDITION TO CEMENT & CONCRETE
PARTIAL REPLACEMENT FOR CEMENT IN FOLLOWING TWO WAYS:
CEMENT MANUFACTURING UNIT:
SEPARATE GRINDING OF BFS & CLINKER & MIXING ALONG
WITH GYPSUM IN A MECHANICAL BLENDING UNIT
INTERGRINDING OF BFS, CLINKER & GYPSUM
CONCRETE MAKING SITE: GGBS OF DESIRED FINENESS
ADDED TO CONCRETE, TO REPLACE CEMENT PARTIALLY
MOST WORLD STANDARDS LIMIT THE ADDITION OF BFS IN SLAG
CEMENT UP TO 70%
HIGHER REPLACEMENTS ADVANTAGEOUS FOR CERTAIN
APPLICATIONS
30. HYDRATION
HYDRATION: COMBINATION OF ALL CHEMICAL & PHYSICAL PROCESSES
OCCURING, AFTER CONTACT OF ANHYDROUS SOLID WITH WATER
HYDRATION PERIODS:
WORKABILITY PERIOD: 1–3 h: VERY LOW RATE (DORMANT) HYDRATION:
WETTING, MIXING, TRANSPORTING, AGITATING, PLACING & FINISHING OF
CONCRETE
SETTING PERIOD: MIN IST > 60 min & MAX. FST RANGE 3–5 h: ACTIVE
REACTION: CUIRING CAN START AFTER FST
HARDENING PERIOD: ABOUT 28 DAY: DECELERATION & SLOW REACTION:
CURING TO CONTINUE FOR 7 TO 14 DAYS
31. HYDRATION
WITH MINERAL ADMIXTURES
FIVE PRINCIPAL MINERAL ADMIXTURES: PFA, BFS, SF, RHA, & MK,
ARE EITHER POZZOLANIC OR CEMENTITIOUS
CH REACTS WITH BOTH POZZOLANIC & CEMENTITIOUS
ADMIXTURES TO FORM ADDITIONAL CEMENTITIOUS PRODUCTS
ADMIXTURE HYDRATION PRODUCES MORE C-S-H, WHICH LEADS
TO HIGHER STRENGTH
HYDRATION DOES NOT BEGIN UNTIL AMORPHOUS MINERALS
(GLASS) DISSOLVES & REACTS WITH CH
PFA ADDITION: WORKABILITY IMPROVES OR WATER
REQUIREMENT DECREASES, FOR GIVEN WORKABILITY
IST & FST INCREASE: WITH REPLACEMENT BUT STRENGTH
DEVELOPMENT REMAINS APPROPRIATE
CURING: PROVIDE PROPER CURING TEMPERATURE & MOISTURE
FOR UP TO A WEEK
32. STRENGTH & DURABILITY
DURABILITY: ABILITY OF STRUCTURE TO RESIST WEATHERING
ACTION, CHEMICAL ATTACK & ABRASION, MAINTAINING MIN
STRENGTH & OTHER DESIRED ENGINEERING PROPERTIES
DESIGNING FOR STRENGTH & DURABILITY SYNONYMOUS TO
DESIGNING FOR SUSTAINABILITY
NATIONAL STANDARDS MOSTLY PRESCRIPTIVE , DEFINING
EXPOSURE CONDITIONS, DESIGN PROCEDURE, BUILDING
MATERIALS & THEIR APPLICATION, NOT ASSURING MIN SERVICE
LIFE OF STRUCTURE, WHEN SPECIFICATIONS ARE FOLLOWED
DURABILITY DEPENDS UPON BOTH EXPOSURE ENVIRONMENT &
QUALITY OF CONCRETE
33. STRENGTH & DURABILITY
DESIGNING FOR DURABILITY
PERMEABILITY IS THE SINGLE MOST IMPORTANT CRITERION FOR
DURABILITY
TWO MAJOR FAULTS IN CONCRETE CONSTRUCTION THAT CAN
LEAD TO THE LOSS OF DURABILITY: INADEQUATE COVER TO
REINFORCEMENT & INADEQUATE COMPACTION OF COVER
CONCRETE
QUALITY CONTROL NORMS FOR CONSTRUCTION MATERIALS
WELL ESTABLISHED, BUT PRACTICALLY NONEXISTENT FOR
CONSTRUCTION PROCESS
34. STRENGTH & DURABILITY
CONCRETE STRENGTH
STRENGTH OF CONCRETE CONTAINING MINERAL ADMIXTURES,
f(ADMIXTURE)
f(ADMIXTURE) = f(DILUTION) + f(PHYSICAL) + f(CHEMICAL)
f(DILUTION) = REDUCED STRENGTH PROPORTIONAL TO
AMOUNT OF CEMENT IN MIXTURE
f(PHYSICAL) = INCREASE IN STRENGTH DUE TO PHYSICAL
EFFECT OR HETEROGENEOUS NUCLEATION & FILLER EFFECT
DUE TO MINERAL ADMIXTURE
f(CHEMICAL): INCREASE IN STRENGTH RELATED TO
POZZOLANIC REACTION
35. STRENGTH & DURABILITY
INTERFACIAL TRANSITION ZONE
(ITZ)
0% SF 10% SF
SEM IMAGES OF CONCRETE ITZ MICROSTRUCTURE AT 28 DAYS WITH 0%
& 10% BY MASS OF SF. 7.6
38. STRENGTH & DURABILITY
IMPORTANCE OF CURING
CURING: IS A PROCESS OF PREVENTING LOSS OF MOISTURE FROM
CONCRETE, WHILE MAINTAINING SATISFACTORY TEMPERATURE REGIME
EARLY & LONG TERM CURING IS BENEFICIAL FOR DEVELOPMENT OF
CONCRETE PROPERTIES
MOISTURE LOSS PREVENTION IMPORTANT WHEN w/c RATIO IS LOW,
WHEN CEMENT HAS A HIGH RATE OF STRENGTH DEVELOPMENT & WHEN
CONCRETE CONTAINS MINERAL ADMIXTURES
ADEQUATE & CONTINUOUS SUPPLY OF WATER IS NECESSARY FOR
LONG-TERM STRENGTH DEVELOPMENT & IMPROVED DURABILITY
PERFORMANCE OF CONCRETE WITH MINERAL ADMIXTURES
40. STRENGTH & DURABILITY
ROLE OF MINERAL ADMIXTURE
REDUCE CONCRETE DETERIORATION BY: (A) CARBONATION, (B) ASR, (C)
CORROSION OF REINFORCEMENT, (D) SULFATE ACTION, (E) DECALCIFICATION OR
LEACHING & (F) FROST ACTION
WHEN MINERAL ADMIXTURE IS USED:
(A) FIXES ALKALI: ABOUT 95% ALKALIS FIXED THROUGH ADSORPTION OR SOLID
SOLUTION
(B) SECONDARY C-S-H: FORMED BY SECONDARY HYDRATION, FILLS UP PORES
IN HARDENED CEMENT PASTE, MAKING PORE STRUCTURE FINER & DENSER
(C) REDUCES C3A: PREVENTS SULFATE ATTACK
(D) CH REDUCTION: LEADS TO REDUCTION IN CaSO4 GENERATION & HELPS
MITIGATE SULFATE ATTACK
(E) PERMEABILITY REDUCTION THRU PACKING EFFECT OF UNREACTED
PARTICLES
(F) CHLORIDE BINDING: SOME MINERAL ADMIXTURES HAVE GREATER CHLORIDE-
BINDING CAPACITY IN COMPARISON TO PC
41. STRENGTH & DURABILITY
CARBONATION
CARBONATION: PRECIPITATION OF CALCITE (CaCO3) & OTHER
CO2-BASED SOLID COMPUNDS, THROUGH REACTION OF
PENETRATING ATMOSPHERIC CO2 WITH Ca IONS IN PORE
SOLUTION
pH DROP: DROP OF pH OF PORE SOLUTION OF CONCRETE
FROM 12.5–13.5 TO ABOUT 8.3, SO THAT PASSIVE IRON OXIDE
LAYER THAT USUALLY COVERS & PROTECTS REINFORCING STEEL
AGAINST CORROSION, BECOMES UNSTABLE
C-S-H LOSS: WITH CONSTANT CO2 DIFFUSION, CH GETS
FURTHER DEPLETED & CALCIUM FROM C-S-H ALSO REACTS,
LEADING TO LOSS OF STRENGTH, VOLUMETRIC DECREASE
(SHRINKAGE) & CRACKING & INCREASE IN CONCRETE POROSITY
43. STRENGTH & DURABILITY
CARBONATION
INCREASES WITH CO2 CONCENTRATION IN SURROUNDINGS
NORMAL ATMOSPHERIC CONDITIONS & RH OF 50%–80%
OPTIMUM
JAN BIJEN et.al.: LARGE SCALE STUDY ON DURABILITY OF
STRUCTURES BUILT ALONG DUTCH COAST, WITH BFS CONCRETE (.)
STRUCTURES INCLUDED SLUICES, PIERS & QUAYS, RANGING IN
AGE FROM 3 TO 63 YRS (.) IN 48 OUT OF 51 STRUCTURES,
CARBONATION DEPTH WAS < 5 mm
EARLY & LONGER CURING GIVES BETTER CARBONATION
RESISTANCE, ESPECIALLY IN CONCRETE WITH MINERAL
ADMIXTURES
44. STRENGTH & DURABILITY
ALKALI-AGGREGATE REACTIONS
(AAR)
AAR: WHEN AGGREGATES CONTAINING CERTAIN DOLOMITIC (Ca +
Mg) OR SILICEOUS MINERALS REACT WITH SOLUBLE ALKALIES IN
CONCRETE
SOMETIMES RESULT IN DETRIMENTAL EXPANSION, CRACKING &
PREMATURE LOSS OF SERVICEABILITY OF CONCRETE
STRUCTURES AFFECTED
ALL KINDS OF CONCRETE STRUCTURES MAY BE AFFECTED (.)
STRUCTURES IN DIRECT CONTACT WITH WATER, SUCH AS DAMS &
BRIDGES, ARE PARTICULARLY SUSCEPTIBLE TO AAR
TWO TYPES OF AAR: (A) ALKALI–CARBONATE REACTION (ACR) &
(B) ALKALI–SILICA REACTION (ASR)
45. STRENGTH & DURABILITY
ALKALI-AGGREGATE REACTIONS
(ACR & ASR)
ALKALI-CARBONATE REACTION (ACR)
PROCESS OF DEGRADATION OF CONCRETE CONTAINING
DOLOMITIC (DOLOMITE: CaCO3.MgCO3 ) AGGREGATE
SEPARATION OF CALCIUM & MAGNESIUM COMPOUNDS TAKES
PLACE
ALKALI-SILICA REACTION (ASR)
INCREASED REACTIVITY OR INSTABILITY OF AMORPHOUS,
SILICA FOUND IN AGGREGATE ROCKS
ASR MAY BE OBSERVED AFTER 5–25 YEARS OF CONSTRUCTION &
MAY AFFECT ANY CONCRETE STRUCTURE
47. STRENGTH & DURABILITY
ALKALI-AGGREGATE REACTIONS
INITIATION & PROPAGATION: THREE NECESSARY CONDITION: (A)
CRITICAL QUANTITY OF REACTIVE AGGREGATE, (B) SUFFICIENT ALKALI IN
CONCRETE & (C) SUFFICIENT MOISTURE
ALKALI CONTENT IN CEMENT EXPRESSED AS “SODIUM OXIDE
EQUIVALENT”
(MASS PERCENT) Na2Oeq = Na2O + 0.658 K2O
HARMLESS ALKALI CONTENT: < 0.6% Na2Oeq IN CEMENT OR < 1.8 Kg/m3
IN CONCRETE
ASTM C1260, ACCELERATED MORTAR BAR TEST (AMBT), IS MOST WIDELY
USED TEST METHOD
MINERAL ADMIXTURES REPLACING CEMENT, SUCH AS BFS, PFA &
NATURAL POZZOLANS, MITIGATE OR ELIMINATE AAR IN CONCRETE
HIGHER REPLACEMENTS GOOD: SIGNIFICANT REDUCTION IN AAR
EXPANSION ACHIEVED FOR PFA (>25%) OR BFS (>40%) OR COMBINATION OF
BOTH
49. STRENGTH & DURABILITY
CORROSION
CHLORIDE ATTACK & CORROSION OF REINFORCEMENT
WHEN CHLORIDE IONS PENETRATE THROUGH POROUS
CONCRETE & BUILD UP AROUND REINFORCEMENT & ALKALINITY
(pH) OF SURROUNDING PORE SOLUTION FALLS SUBSTANTIALLY,
PROTECTIVE IRON OXIDE FILM DEPASSIVATES & CRACKS,
EXPOSING STEEL
EXPOSED STEEL GETS CORRODED IN PRESENCE OF WATER &
OXYGEN, RESULTING IN FORMATION OF EXPANSIVE CORROSION
PRODUCTS (RUST) THAT OCCUPY SEVERAL TIMES VOLUME OF
ORIGINAL STEEL CONSUMED
EXPANSIVE CORROSION PRODUCTS CREATE TENSILE STRESS IN
CONCRETE SURROUNDING CORRODING STEEL REBAR, LEADING
TO CRACKING & SPALLING OF CONCRETE COVER
50. STRENGTH & DURABILITY
CORROSION
AASHTO T259: 90-DAY SALT-PONDING TEST TO EVALUATE CHLORIDE
DIFFUSION COEFFICIENT, REQUIRES LONG-TERM PONDING (IN YEARS) TO
OBTAIN RELIABLE ESTIMATES OF CHLORIDE DIFFUSION COEFFICIENT
RAPID CHLORIDE PERMEABILITY TEST (RCPT), ASTM C1202: DEVELOPED
TO NON-DESTRUCTIVELY OBTAIN INDICATION ON CHLORIDE PERMEABILITY
OF CONCRETE, IN A SHORT TIME PERIOD
RCPT CORRELATES CONCRETE RESISTIVITY WITH PERMEABILITY
MINERAL ADMIXTURES IMPART ENHANCED RESISTANCE TO DIFFUSION
OF CHLORIDE IONS & OTHER DETERIORATING AGENTS, ON ACCOUNT OF
REFINEMENT OF PORE STRUCTURE
CORROSION INITIATION DELAYED & PROPAGATION EXTENDED
AASHTO: American Association of State Highway and Transport Officials
52. STRENGTH & DURABILITY
CORROSION
FLY ASH CONCRETE IS USED UNDER SEVERE EXPOSURE CONDITION SUCH AS
IN DECKS & PIERS OF SUNSHINE SKYWAY BRIDGE, TAMPA BAY, FLORIDA
53. STRENGTH & DURABILITY
CORROSION
HUNGRY HORSE DAM, ON MONTANA’S FLATHEAD RIVER (.) ONE
OF THE LARGEST CONCRETE-ARCH DAMS IN USA,
COMPLETED IN 1953, WAS BUILT WITH 120,000 T OF FLY ASH
54. STRENGTH & DURABILITY
EXTERNAL SULFATE ATTACK
HIGH C3S & C3A CONTENT IN PC REDUCES RESISTANCE TO
SULFATE ATTACK
PARTIAL REPLACEMENT OF PC WITH MINERAL ADMIXTURES
REDUCES C3S & C3A IN BLEND
Na2SO4: CONCRETE WITH MINERAL ADMIXTURES SHOWS
LOWER EXPANSION
MgSO4: CONCRETE WITH MINERAL ADMIXTURES SHOWS HIGHER
STRENGTH REDUCTION, IN COMPARISON TO THAT WITH PC
NEGATIVE EFFECT OF MINERAL ADMIXTURES, DURING MgSO4
ATTACK OFTEN OFFSET BY REDUCED PERMEABILITY &
DENSIFICATION CAUSED BY THEIR USE
APPLICATION OF PROTECTIVE COATING LIKE EPOXY
RECOMMENDED ON CONCRETE SURFACE EXPOSED TO MgSO4
ENVIRONMENT
7.29
55. STRENGTH & DURABILITY
EXTERNAL SULFATE ATTACK
Al2O3 (ALUMINA) CONTENT OF BFS IS SAID TO LOWER ITS
SULFATE RESISTANCE (.) HOWEVER THERE IS NO DIRECT
RELATIONSHIP, AS A PART OF Al2O3 IS TAKEN UP IN C-S-H
STRUCTURE, WHERE IT IS LESS PRONE TO SULFATE ATTACK
BLENDED CEMENT WITH > 60% BFS, SHOWS MODERATE
TO GOOD SULFATE RESISTANCE, IRRESPECTIVE OF Al2O3
CONTENT OF SLAG
WITH REGARD TO PFA, REPLACEMENT LEVEL OF 25%–30%
OF CEMENT INCREASES SULFATE RESISTANCE OF
CONCRETE
56. STRENGTH & DURABILITY
FREEZE-THAW ACTION
DETERIORATION OF CRITICALLY SATURATED CONCRETE DUE TO FREEZING OF
WATER
TYPICAL SIGNS OF FREEZE–THAW DETERIORATION: SPALLING & SCALING, LARGE
CHUNKS OF CONCRETE (cm SIZE) BREAKING OFF, EXPOSED AGGREGATE & SURFACE
PARALLEL CRACKING
AIR VOIDS WITHIN CONCRETE PROVIDE GOOD FROST RESISTANCE
PORE SYSTEM IN SOME AGGREGATES SHOW SUSCEPTIBILITY TO DAMAGE FROM
FREEZE–THAW (.) HENCE EFFORTS ARE ALSO FOCUSED ON IDENTIFYING DAMAGE-
RESISTANT AGGREGATES
CONCRETE WITH HIGH WATER CONTENT & HIGH W/C RATIO IS LESS FROST
RESISTANT THAN CONCRETE WITH LOWER WATER CONTENT
FREEZE–THAW RESISTANCE OF CONCRETE CONTAINING 30%–50% PFA REPLACING
CEMENT, SHOWED EXCELLENT RESULTS
D-CRACKING: CRACKING OF CONCRETE, MOSTLY IN PAVEMENTS, CAUSED BY
FREEZE–THAW DETERIORATION OF COARSE AGGREGATE WITHIN CONCRETE
TO PREVENT D-CRACKING: SELECT DURABLE MATERIALS
58. DISCUSSION
DISCUSSION MAY CONTINUE ON THE FOLLOWING
WHATSAPP GROUP:
MODERN CONCRETE
SEND: YOUR NAME, DESIGNATION, COMPANY
TO Dr J D BAPAT MOBILE: 9422517402
60. DISCUSSION
DISCUSSION MAY CONTINUE ON THE FOLLOWING
WHATSAPP GROUP:
MODERN CONCRETE
SEND: YOUR NAME, DESIGNATION, COMPANY
TO Dr J D BAPAT MOBILE: 9422517402