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• Transportation engineering deals with planning, designing, implementing and maintaining the various modes of transportation system and infrastructure that required for transporting people and goods from one place to another.
• Transportation contributes to the economic, industrial, social and cultural development of any country. So, transportation plays vital role for economic development of any region.
• The main objective of good transportation system is to provide safe, economical, efficient transportation facility for the travel of passenger and transportation of goods.

1.2 Modes of transportation

A. Primary modes

1. Land transportation

a. Highways (Road ways)

Merit:

• Wide geographical coverage.
• Door to door service.
• High employment potential.
• Low initial investment.
• Economic for short distance.

Demerit:

• Environmental pollution.
• Low safety.
• High cost for long travel.

b. Railway

Merit:

• Economic for large distance.
• Fixed route.
• No traffic conjunction.
• Can transport large number of passenger and large quality of goods.

Demerit:

• Not economic for short distance.
• High initial investment.
• No different route.
• Material cost for construction is high.

2. Air transportation

Merit:

• Fastest mode of transportation.
• Large distance covered.
• Safe and comfortable.
• Connection to remote place is possible.

Demerit:

• High initial investment.
• Affected by weather condition.

3. Waterways

Merit:

• Economic for heavy load.
• Operating cost is low.
• Low environmental effect.
• Safest mode.

Demerit:

• Slow moving of transportation.
• Affected by weather condition.
• Chances of water pollution due to oil leakage.

4. Pipeline transportation

Merit:

• Can be laid over difficult terrain as well as under water.
• Operation and maintenance cost is low.

Demerit:

• Security of pipeline is difficult.
• Initial cost is high.

B. Secondary modes

1. Ropeways

• Economic.
• Used in steep slope.
• Environmental friendly.

2. Belt conveyors

• Provide steady movement of material.
• Used in industries for transport of goods.

3. Canal

• Used in transportation for irrigation system in rural areas.

1.3 Comparison between various modes of transportation

1.4 Historical development of roads

• First mode of transportation was by foot which led to development of footprint.
• Use of animal and development of trackways.

Historical classification of roads:

1.  Roman road (7^th Centuries)

• Built regardless of gradient.
• Used heavy foundation at bottom.
• Concrete was a major roman road making innovation.
• Roads were very costly.

2. Tresaguet road (1764 AD – 1775 AD)

• Also known as French road.
• Side drainage was provided.
• Thickness of construction was only 30 cm.
• Pavement used 200 mm pieces of quarried stone.

3. Telford construction (1757 AD – 1834 AD)

• Also known as England road.
• Slopping surface on the top was provide by varying size of stones in foundation.
• Cross – drains at interval of 90 m was provided.

4. Macadam construction

• First scientific road construction method.
• Economical method.
• Instead of placing large foundation stone, small size broken stone are spread over the prepared subgrade and compacted.
• Proper drainage system was considered.

1.5 Road construction in Nepal

• Government of Nepal has been giving priority to development of roads since the beginning of planned development programmed established in 1956 AD.
• The first motorable road was constructed in the Kathmandu Valley.
• Nepal’s first paved road was built with aid from India in early 1950’s.
• Nepal’s first highway was Tribhuvan highway (25 Km) in 1956 AD.
• The government of China built Araniko highways (115 Km) in 1966 AD.
• Prithivi highway (200 Km) was built in 1974 AD.
• Roads construction in Nepal:
  
  

• Agencies involved in road development of Nepal are:
  • Ministry of Physical Planning and Works
  • DOLIDAR
  • Ministry of Finance
  • National Planning Commission
  • Nepal Army
  • JICA
  • Bilateral Agency (India, UK, Japan, China)
  • Multilateral Agency (AOB, JMF, WB)
  • Swiss Development Cooperation (SDC)

1.6. Transport planning including objective of road planning

• Transport planning is done to develop a reliable, cost effective, safe facility oriented and sustainable transport system that promotes and sustains the economic, social, cultural and tourism development of Nepal as a whole. (According to National Transport Policy 2058 BS)

Objective of transport planning:

• To determine existing road network.
• To collect the demand of road network.
• To mobilize the resource.
• To forecast future need of road in different part of country.
• To improve traffic capacity.

Different studies in project planning survey:

a. Economic Studies

• Population and its distribution pattern.
• Trend of population growth.
• Agricultural and industrial product of the area.
• Possibility of industrial and agricultural development.
• Existing facilities with regard to communication, education, health etc.

b. Financial Studies

• Source of income and estimated revenue.
• Living standard.
• Resources of local level, toll taxes, vehicle registration and fines.
• Future trends in financial aspects.

c. Traffic Studies

• Traffic volume, annual average daily traffic.
• Origin and destination studies.
• Traffic flow pattern.
• Accident, their cost analysis and causes.
• Future trend in traffic volume and pattern.

d. Engineering or Technical Studies

• Topographic survey.
• Soil survey.
• Location and classification of existing road.
• Estimation of possible development in all aspect.
• Road life studies.
• Traffic studies.

e. Long term planning

• Population model.
• Economic activity mode.
• Land use model.
• Traffic assignment model.
• Trip generation model.
• Trip distribution model.
• Model split model.

Types of road planning

a. National Road Network (NRN) planning

• Planning of main highway in Nepal connecting major parts of country, headquarter of regions and large industries and tourist centre including roads required for strategic movement for defense of country.
• Also includes feeder roads.
• East – West and North – South highways.

b. Urban Road Network (URN) planning

• The roads serving within the urban municipalities.
• Urban areas are communication centre for the exchange of goods, service and ideas.

1.7 Classification of roads

• According to Nepal Road Standard 2070 BS roads in Nepal are classified as follows:

A.  Administrative classification

1. National highway

• Main roads connecting east to west and north to south.
• Provide consistently higher level of service in terms of travel speeds.
• Designated by letter ‘H’ followed by a two digit number.
• For example: HO₁, HO₂ etc.

HO₁ – Mahendra Rajmarga

HO₂ – Tribhuvan Rajmarga

• Total national highway = 21

2. Feeder roads

• Connect district, headquarters major economic centre, tourism centre to national highway or other feeder roads.
• Important roads or localized nature.
• Wide community interest.
• Designated by letter ‘F’ followed by three digits.
• For example: FOO₁, FOO₂ etc.

FOO₁ – (Birtamod – Bhadrapur)

FOO₂ – (Balkhu – Dakchhinkali)

• Total feeder roads = 209

3. District roads

• Important roads within a district.
• Serves production areas and market.
• Connecting with each other or with the main highways are district roads.

4. Urban roads

• Roads serving within the urban municipalities are urban roads.

Classification of urban roads:

a. Expressway:

• They are provided for speedy and heavy traffic.
• Pedestrian not allowed.

b. Arterial:

• They are provided for heavy and important traffic inside the city.
• Pedestrians are allowed to cross only at intersections.

c. Sub – arterial:

• They are provided for less traffic than arterial streets.
• Pedestrians are allowed to cross only at intersection.

d. Collector:

• They are provided for indirect and direct access for land users within specific area.
• Full access allowed from properties alongside.

e. Local streets:

• They are provided for direct property access.
• Does not carry large volume of traffic.

Notes:

a. Strategic Road Network (SRN):

• National highway and feeder roads.
• DOR governs strategic road network.

b. Local Road Network (LRN):

• District roads and urban roads.
• DOLIDAR and Local government governs local road network.

B. Technical functional classification

1. Class I (Expressway)

2. Class II (Arterial roads)

3. Class III (Collector roads)

4. Class IV (Local roads)

Notes:

Average daily traffic: ADT

Passenger car unit: PCU

• Unit used for expressing highway capacity.

Road patterns in urban roads:

1. Grid iron pattern:

a. Rectangular or block

b. Hexagonal

Advantage:

• Low cost.
• Simple to plan.
• Efficient in providing drainage and sewerage network.

Disadvantage:

• Offers limited urban design options.
• Can be confusing and frustrating.

2. Radial pattern:

a. Star and block

b. Star and circular

c. Star and grid

Advantage:

• Reduce traffic.
• Less risky as compared to block patterns.
• If one road is blocked another can be used as alternative.

Disadvantage:

• Lack of safety.
• High construction cost.

3. Ring roads:

Advantage:

• Direct access to the town centre like business area, banks, shopping complexes, entertainment centre etc.
• Reduce traffic.

Disadvantage:

• High construction cost.
• Speed has to be limited approx. 100 Kph.

References:

• Sharma, S.K Principles Practice and Design of Highway Engineering. New Delhi: S. Chand and Co. Publisher Ltd.
• Relevant Publication by Department of roads and department of local infrastructure development and agricultural roads (DOLIDAR).

The post The Science of Transportation: An Introduction to Planning and Engineering appeared first on OnlineEngineeringNotes.

Environmental Assessment (EA) is a process of identifying, predicting, evaluating and mitigating the potential environmental impacts of a proposed development project.

In developing countries like Nepal, EA is necessary to:

• Ensure sustainable development and reduce negative impacts on the environment.
• Prevent or minimize environmental degradation and protect natural resources.
• Involve the public in decision-making and increase transparency.
• Comply with international environmental standards and regulations.
• Promote social and economic development while protecting the environment.

2. Nepal is poor country and EIA increase the cost. Justify for or against the statement with examples.

The statement that “Environmental Impact Assessment (EIA) increases the cost in Nepal, a poor country” can be argued for or against, as discussed below:

Argument for the statement:

• Inadequate funding: Developing countries like Nepal may lack sufficient financial resources to conduct a comprehensive EIA, leading to increased costs. This is because the process requires the engagement of various experts, collection and analysis of data, public consultations, and monitoring of environmental impacts, which may be costly.

• Delayed implementation: The EIA process can cause delays in project implementation, which may also increase costs due to additional expenses incurred during the extended project timeline.

Example: The proposed construction of the Nijgadh International Airport in Nepal has faced opposition from environmentalists and local communities who cite concerns about deforestation, wildlife habitat loss, and air pollution. The EIA process for the project has been delayed due to lack of funding and technical expertise, which has caused project costs to increase.

Argument against the statement:

• Long-term benefits: EIA can help identify potential environmental risks and provide recommendations to minimize impacts, which can lead to long-term benefits, such as reduced cleanup costs, enhanced project sustainability, and improved environmental and public health outcomes.

• Attracting funding: EIA can also help attract funding from international donors or financial institutions by demonstrating that a project is environmentally sound, socially responsible, and economically viable.

Example: The construction of the Upper Trishuli-1 Hydroelectric Power Project in Nepal was supported by the Asian Development Bank, in part because of the thorough EIA conducted for the project, which identified and mitigated potential environmental impacts, and demonstrated the project’s sustainability and potential economic benefits.

Environmental Impact Assessment (EIA) is a process of identifying and evaluating the potential environmental impacts of a proposed development project. In Nepal, a developing country, there is a need for EIA to ensure sustainable development and protect the environment.

Regarding the statement that EIA increases the cost, it is true that conducting an EIA involves costs such as hiring experts, conducting studies, and gathering data. However, the benefits of EIA outweigh the costs in the long run. Here are some examples:

• EIA can help prevent costly environmental damages in the future, such as soil erosion, landslides, and water pollution, which can have significant economic and social impacts.
• EIA can identify cost-effective measures to mitigate negative impacts on the environment, such as reforestation or wastewater treatment, which can save costs in the long run.
• EIA can increase transparency and public participation, which can reduce project delays and conflicts, saving time and money in the long run.
• EIA can improve the project’s reputation, leading to increased investment and tourism opportunities, which can benefit the economy in the long term.

In conclusion, while it is true that EIA can increase costs in Nepal, it is also important to consider the long-term benefits and the potential to attract funding and support for environmentally sound and sustainable development projects.

3. If you are appointed as a contractor to conduct a EIA report of any one project how will you proceed describe with suitable flow chart?

The general steps that a contractor would take to conduct an Environmental Impact Assessment (EIA) report for a project.

Step 1: Project Screening

The first step is to determine whether the project requires an EIA report. The contractor will assess the scope, scale, and potential environmental impacts of the project to decide if it falls under the purview of EIA regulations.

Step 2: Scoping

If the project requires an EIA report, the next step is to identify the potential environmental impacts and establish the scope of the study. The contractor will consult with stakeholders, review available data, and conduct site visits to gather information.

Step 3: Impact Assessment

In this step, the contractor will analyze the potential environmental impacts of the project, considering both short-term and long-term effects. The contractor will assess the impact on various environmental components such as air quality, water quality, soil quality, and biodiversity, as well as social and economic impacts.

Step 4: Mitigation Measures

The contractor will recommend mitigation measures to avoid, reduce, or offset potential environmental impacts of the project. The measures may include alternative designs, best practices, and monitoring plans.

Step 5: Public Consultation

The contractor will conduct public consultation to inform and engage stakeholders in the EIA process. This may include holding meetings, presenting reports, and receiving feedback from the public.

Step 6: Report Preparation

Finally, the contractor will prepare a comprehensive EIA report that includes all the findings, recommendations, and mitigation measures. The report will be submitted to the regulatory authorities for approval.

In summary, the contractor will follow a systematic process to identify, assess, and mitigate the potential environmental impacts of a project while engaging stakeholders and complying with regulatory requirements.

4. Scoping is carried out to prioritize the issues for EIA? Describe how do you prioritize them?

Scoping is a critical step in the Environmental Impact Assessment (EIA) process that helps identify the potential environmental and social impacts of a proposed project. Here are the steps to prioritize issues during scoping:

• Identify the project’s purpose and need.
• Identify potential environmental and social impacts of the project.
• Determine the significance of the impacts by considering the scale, magnitude, and duration of the impacts.
• Identify potential mitigation measures to reduce or eliminate the impacts.
• Consult with stakeholders, including the public, affected communities, and relevant agencies, to prioritize issues and identify concerns.
• Develop a scoping report that outlines the prioritized issues and concerns, including any data gaps or uncertainties that require further investigation.

In summary, prioritizing issues during scoping involves identifying, assessing, and consulting with stakeholders to determine the potential environmental and social impacts of a proposed project, and developing mitigation measures to address those impacts.

5. How do you ensure public participation in EIA? Do you think it is necessary for the public to know about environmental Impacts?

Public participation is a crucial component of the Environmental Impact Assessment (EIA) process, as it allows for the engagement of stakeholders in the decision-making process and promotes transparency and accountability. Here are some ways to ensure public participation in EIA:

• Providing public notices: Contractors can publish notices in local newspapers, on websites, and social media to inform the public about the project and the EIA process.

• Conducting public meetings: Contractors can hold public meetings to inform the public about the project, the EIA process, and to receive feedback and comments from the public.

• Conducting public hearings: Contractors can conduct public hearings to provide a forum for the public to express their concerns and opinions about the project and the EIA report.

• Disseminating information: Contractors can distribute EIA reports, environmental impact statements, and other project documents to the public in various languages.

• Providing public comment periods: Contractors can provide a public comment period to allow interested parties to submit their feedback and concerns regarding the project.

Yes, it is necessary for the public to know about environmental impacts because they are the ones who will be directly or indirectly affected by the project. The public can provide valuable feedback on potential environmental and social impacts, and their concerns should be taken into consideration during the decision-making process.

In summary, ensuring public participation in the EIA process is crucial to promote transparency, accountability, and public awareness of the potential environmental impacts of a proposed project.

6. What do you mean by alternative analysis? If you are preparing a EIA report what alternatives you need to consider?

Alternative analysis is a process of identifying and evaluating alternative actions or options to a proposed project that may have fewer or different environmental and social impacts. In an Environmental Impact Assessment (EIA) report, alternative analysis typically involves identifying and assessing the potential impacts of a range of project alternatives, including a “no-action” alternative, which serves as a baseline against which to compare the proposed action.

When preparing an EIA report, some of the alternatives that should be considered during the alternative analysis include:

• No-Action Alternative: This alternative assumes that the proposed project will not be implemented, and no environmental impacts will result.

• Site Selection Alternatives: These alternatives involve identifying different project locations or sites that may have fewer environmental and social impacts than the proposed site.

• Design Alternatives: These alternatives involve modifying the project design to reduce environmental and social impacts.

• Technology Alternatives: These alternatives involve assessing different technologies that may be used to achieve the project’s goals while reducing environmental and social impacts.

• Operational Alternatives: These alternatives involve considering different operating scenarios that may have different environmental and social impacts, such as alternative routes, schedules, and methods of operation.

In summary, alternative analysis involves considering a range of project alternatives to identify the potential environmental and social impacts of each alternative, and to identify the alternative that best meets the project’s goals while minimizing environmental and social impacts.

7. What is sustainable development? Do you think EIA helps in attaining aims of sustainable development? Give examples.

Sustainable development is a concept of meeting the needs of the present generation without compromising the ability of future generations to meet their own needs. In other words, it involves balancing economic, social, and environmental factors to ensure that development is sustainable and does not deplete natural resources or harm the environment.

Environmental Impact Assessment (EIA) plays an important role in achieving the aims of sustainable development by identifying and assessing the potential environmental and social impacts of proposed development projects. By considering the potential impacts of a proposed project on the environment, ecosystems, and local communities, EIA helps decision-makers to make informed decisions about the project that take into account the long-term economic, social, and environmental implications.

Examples of how EIA helps to attain the aims of sustainable development include:

• Renewable Energy Projects: EIA helps in identifying the potential impacts of renewable energy projects on the environment and local communities, and in selecting the most sustainable and environmentally friendly technologies.

• Infrastructure Development: EIA helps in assessing the potential impacts of infrastructure projects on the environment and local communities, and in identifying alternative designs or locations that may have fewer environmental impacts.

• Sustainable Agriculture: EIA helps in identifying the potential impacts of agricultural projects on the environment and local communities, and in promoting sustainable agriculture practices that reduce the use of harmful chemicals, conserve natural resources, and promote biodiversity.

Overall, EIA plays a crucial role in promoting sustainable development by ensuring that development projects are designed, implemented, and managed in a way that minimizes their environmental and social impacts and supports the long-term well-being of local communities and ecosystems.

8. What are the differences between IEE and EIA?

Here are some key differences between Initial Environmental Examination (IEE) and Environmental Impact Assessment (EIA) presented in a simple table:

Overall, while both IEE and EIA are aimed at identifying and addressing potential environmental impacts of development projects, EIA is a more comprehensive and detailed process that is required for larger and more complex projects and involves public participation and approval from regulatory bodies.

9. What is the importance of terms of reference in EIA study?

The terms of reference (TOR) are a crucial aspect of an Environmental Impact Assessment (EIA) study as they provide a framework for the study and guide the assessment process. Here are some key reasons why the TOR is important:

• Clarifies the Scope of the Study: The TOR defines the boundaries of the study, including the project area, the type of impacts to be assessed, and the mitigation measures to be considered.

• Ensures Consistency: The TOR provides a consistent framework for the study, ensuring that all potential impacts are considered and assessed in a systematic manner.

• Provides Guidance for Stakeholders: The TOR outlines the requirements for stakeholder involvement, including public consultation and input from relevant government agencies.

• Ensures Compliance with Regulations: The TOR outlines the regulatory requirements for the study, ensuring that the assessment meets the standards set by the relevant regulatory bodies.

• Facilitates Communication: The TOR provides a common understanding between the project proponent, the environmental consultant, and the regulatory authorities on the requirements for the study, facilitating communication and ensuring that the study is completed efficiently.

Overall, the TOR plays a critical role in ensuring that the EIA study is conducted in a systematic and consistent manner, addressing all relevant environmental and social impacts and ensuring compliance with regulatory requirements.

10. What is the necessary of baseline survey in EIA study? What are the necessary investigations necessary in baseline information?

A baseline survey is a crucial component of an Environmental Impact Assessment (EIA) study as it provides a comprehensive understanding of the existing environmental and social conditions in the project area. Here are some reasons why a baseline survey is necessary:

• Establishes the current state of the environment: The baseline survey establishes the current environmental and social conditions in the project area, including information on land use, topography, soils, water resources, air quality, flora and fauna, cultural heritage, and socio-economic conditions.

• Identifies the potential impacts of the project: The baseline survey identifies the potential environmental and social impacts that may arise from the proposed project, providing a basis for the impact assessment.

• Provides a basis for comparison: The baseline survey provides a basis for comparison of the pre-project and post-project conditions, enabling the assessment of the effectiveness of mitigation measures.

• Facilitates stakeholder engagement: The baseline survey provides a basis for stakeholder engagement, enabling the identification of concerns and issues of local communities and other stakeholders.

Some of the necessary investigations in baseline information include:

• Geographical and topographical survey
• Hydrological and meteorological survey
• Ecological survey including flora and fauna assessment
• Soil and geology survey
• Socio-economic survey including demographic, livelihood and cultural aspects.

Overall, a baseline survey provides the necessary information to develop an accurate and comprehensive EIA report, and serves as a key basis for decision-making by project developers and regulatory authorities.

11. What is relevancy of monitoring in EIA? What are different types of monitoring used in Environmental Assessment?

Monitoring is a critical component of Environmental Impact Assessment (EIA) as it allows for the tracking of the predicted impacts of a project and the effectiveness of mitigation measures over time. Here are some reasons why monitoring is relevant in EIA:

• To ensure compliance: Monitoring ensures that project developers comply with the conditions set by regulatory authorities.

• To detect unforeseen impacts: Monitoring can detect any unforeseen impacts of the project that were not identified during the EIA study.

• To evaluate effectiveness of mitigation measures: Monitoring can evaluate the effectiveness of mitigation measures that were put in place to manage the predicted impacts.

• To inform adaptive management: Monitoring can provide information to inform adaptive management, enabling changes to be made to the project design or mitigation measures if required.

The different types of monitoring used in Environmental Assessment are:

• Compliance monitoring: This type of monitoring is conducted to ensure that the project is complying with the conditions set out in the environmental permit.

• Impact monitoring: This type of monitoring is conducted to measure the predicted impacts of the project on the environment and to evaluate the effectiveness of the mitigation measures.

• Programmatic monitoring: This type of monitoring is conducted over the lifetime of the project to track the effectiveness of the environmental management program.

• Surveillance monitoring: This type of monitoring is conducted to detect unforeseen impacts of the project that were not identified during the EIA study.

Overall, monitoring is essential in EIA as it provides information to improve project design and management, and ensures that the project is being developed in an environmentally and socially responsible manner.

12. What are beneficial and adverse impacts of a Project? Describe the likely beneficial impacts of a hydropower project. Also enlist different construction and operational stage adverse impacts of a road project.

Beneficial impacts of a project refer to the positive outcomes that a project can bring, such as economic development, job creation, or improved infrastructure. Adverse impacts, on the other hand, refer to negative outcomes that can result from a project, such as environmental degradation, social displacement, or health impacts.

For example, a hydropower project can bring several beneficial impacts, such as:

• Increased availability of electricity and reduced reliance on fossil fuels.
• Job creation and economic development in the local area.
• Improved irrigation and flood control downstream of the project.
• Improved water quality in the downstream river due to the management of water flows.

However, a hydropower project can also have adverse impacts such as:

• Displacement of local communities and loss of livelihoods.
• Impacts on fish populations and other aquatic life due to the alteration of water flows.
• Impacts on downstream water users, such as farmers or households, due to changes in the water flow.
• Alteration of natural river processes, such as sediment transport, that can have downstream impacts.

Similarly, a road project can have beneficial impacts such as:

• Improved access to markets, services, and employment opportunities.
• Reduced travel time and transportation costs.
• Improved emergency response and access to health care services.

However, a road project can also have adverse impacts such as:

• Destruction of natural habitats, loss of biodiversity, and fragmentation of wildlife habitats.
• Soil erosion and increased sedimentation in rivers due to construction activities.
• Displacement of communities, loss of homes, and impacts on cultural heritage sites.
• Increased traffic congestion, noise pollution, and air pollution due to increased traffic flows.

It is important for an Environmental Impact Assessment (EIA) study to identify and assess both the beneficial and adverse impacts of a project, and develop appropriate mitigation measures to minimize the adverse impacts and enhance the beneficial impacts.

13. What is the significance of screening in Environmental assessment? What do you understand by threshold in Environment Assessment?

• Screening is the initial step in Environmental Assessment (EA) process.
• Its significance lies in identifying whether a proposed project or activity is likely to have significant environmental impacts that require a full Environmental Impact Assessment (EIA) study or whether the impacts are minimal and require only an Initial Environmental Examination (IEE) study.
• Screening helps to identify projects that are likely to have significant environmental impacts early in the project development process, allowing project developers to consider alternatives or modifications to the project design that can avoid or minimize adverse environmental impacts.
• Thresholds are specific criteria or standards that are used to determine whether the environmental impacts of a proposed project or activity are significant enough to require a full EIA study.
• Thresholds can be based on various factors such as the size, nature, location, and potential impacts of the project.
• If the proposed project meets or exceeds the threshold, then it is deemed to have the potential for significant environmental impacts, and a full EIA study is required.
• If it falls below the threshold, then it may be eligible for an IEE study or may not require any further assessment at all.

14. What do you mean by mitigation measures? Describe the necessity of avoidance minimization and compensation in Environment Assessment? Give examples.

Mitigation measures are actions taken to avoid, minimize or compensate for adverse environmental impacts of a proposed project.

• Avoidance: Avoidance measures aim to eliminate or prevent environmental impacts by altering the project design or locating the project in a less sensitive area. For example, avoiding construction in areas of high biodiversity, or avoiding sensitive cultural or historical sites.

• Minimization: Minimization measures aim to reduce the severity or magnitude of environmental impacts through the project design or operation. For example, using noise barriers to reduce noise impacts or using low-emission vehicles to reduce air pollution.

• Compensation: Compensation measures aim to offset the residual environmental impacts that cannot be avoided or minimized by restoring or enhancing the environment elsewhere. For example, compensating for the loss of wetlands by creating new wetlands in another area.

The necessity of avoidance, minimization and compensation measures in Environmental Assessment (EA) is to ensure that the proposed project does not cause irreversible harm to the environment and communities.

• Avoidance measures can help to prevent significant environmental impacts from occurring in the first place.

• Minimization measures can help to reduce the severity or magnitude of impacts that cannot be avoided, reducing the overall environmental damage.

• Compensation measures can help to offset the residual impacts that cannot be avoided or minimized by restoring or enhancing the environment elsewhere, ensuring that the project has a net positive impact on the environment.

Examples of mitigation measures include:

• Avoiding sensitive areas like wetlands, cultural heritage sites or habitats of endangered species.
• Installing noise barriers or designing sound-proof buildings to reduce noise pollution.
• Using low-emission vehicles or designing energy-efficient buildings to reduce air pollution and greenhouse gas emissions.
• Creating new habitats or restoring degraded ecosystems to compensate for habitat loss.
• Providing financial compensation or alternative livelihoods to communities affected by the project.

15. EIA report is backbone of the project development. Justify the requirement and necessity of good EIA report.

The Environmental Impact Assessment (EIA) report is a crucial component in the project development process, as it provides critical information regarding the potential environmental impacts of a proposed project. A well-prepared EIA report is necessary to ensure that the project is designed and implemented in an environmentally sound manner.

The requirement for a good EIA report is justified based on the following reasons:

• A good EIA report provides a comprehensive assessment of potential environmental impacts of a proposed project.
• It helps in identifying and evaluating various alternatives to the project.
• It provides a platform for public participation and ensures transparency in the decision-making process.
• It helps in obtaining regulatory approvals and permits for the project.
• A well-prepared EIA report can help in reducing project risks and avoiding potential environmental liabilities.
• It can also provide important information to investors and lenders, improving project credibility and financial viability.
• A good EIA report can help in achieving sustainable development goals by balancing economic, social, and environmental considerations.

Overall, a good EIA report is essential for ensuring that a proposed project is designed and implemented in an environmentally sustainable manner that benefits both the project developers and the surrounding communities.

16. What is environmental Auditing? Describe the role of different players in EIA study in Environmental Auditing

Environmental auditing is a systematic process of evaluating the performance of an organization or a project against environmental standards and regulations. It is a tool for assessing the effectiveness of environmental management systems and identifying areas for improvement.

In an EIA study, the different players involved in the environmental auditing process include:

• Project proponent – responsible for implementing environmental management measures and ensuring compliance with environmental standards.
• Regulatory agencies – responsible for enforcing environmental regulations and conducting inspections to ensure compliance.
• Independent auditors – hired by the project proponent or regulatory agencies to assess the environmental performance of the project and identify areas for improvement.
• Stakeholders – including the public, NGOs, and other interested parties, who can provide feedback and input on the environmental performance of the project.

The role of these players in environmental auditing is to ensure that the project is being developed and operated in an environmentally responsible manner, and to identify any areas where improvements can be made to minimize environmental impacts.

The post A Beginner’s Guide to Understanding Environmental Impact Assessments appeared first on OnlineEngineeringNotes.

Soil investigation:

The process of collecting information about subsurface and taking sample to determine profile of natural soil deposits and engineering properties of soil.

Soil exploration:

The field and laboratory studies carried out for obtaining necessary information about sub soil characteristics including the position of ground water table.

Objective of soil exploration:

• To determine ground water condition in the site.
• To select suitable construction technique.
• To predict and solve potential foundation problem.
• To investigate safety of existing structure.
• To conduct in-situ test to asses appropriate soil characteristics.

Method of soil exploration:

1. Direct method

• It helps to conduct visual inspection of the site locating different strata of the soil and its boundaries.
• It helps to obtain undisturbed sample.

Types of direct method:

a. Test pit

• Depth up to 3 m.
• Uneconomical at greater depth.
• Open type exploration.

b. Trial pits

• Used to recover large bulk sample of soil.

c. Trench

• Used for searching and excavating ancient ruins.

2. Semi-direct method

• Drilling a hole into the soil strata to specified depth is known as boring.

Types of boring:

a. Auger boring

• Trenchless technology used to install steel casing pipe in a variety of soil condition.

b. Auger and shell  boring

• Useful in obtaining sample of sand and gravel from below the water table.

c. Wash boring

• Simple and fast method of soil exploration for cohesive soil and sand or gravel without boulders.

d. Rotary drilling

• Used to form a deep observation.

e. Percussion drilling

• Used for making holes in rocks, boulder and hard strata.

3. Indirect method

• It is also known as geophysical method.
• It helps to measure physical properties of soil such as electrical resistive, vibration and gravitational field.

1.2 Soil sampling, types of sample, soil samplers and its basic requirement for cohesive soil

Soil sampling

• Process of extracting soil sample from drilling tools and sampling equipment.

Types of sample:

1. Disturbed sample

• Natural structure of soil gets modified partly or fully during sampling.

a. Non-representative sample

• Sample obtained from auger boring and wash boring.
• Provides information of major change in sub-surface strata.
• Gives rough idea about soil and its stratification.

b. Representative sample

• Suitable for identification and determination of certain physical properties such as Atterberg limit, specific gravity of soil.

2. Undisturbed sample

• Original soil structure is preserved without modification.
• Practically impossible to get undisturbed sample.
• Tube and chunk sample are considered as undisturbed sample.

Types of samplers:

1. Open driven sampler

• Thin walled tube which can be pushed or driven into soil at the bottom of the hole and then rotated to detached the lower end of the sample from the soil.

2. Split spoon sampler

• Used in standard penetration test (SPT).
• It is tube split into two equal halves length wise.

3. Thin wall sampler

• A sampler introduce very less disturbance to the soil sample.
• Used for collecting undisturbed soil sample.

4. Piston sampler

• Special type of thin walled sampler with piston inside.
• Sampling is pushed into the soil hydraulically by keeping the piston stationary.
• Excellent tool for obtaining very fine undisturbed sample.

5. Rotary sampler

• It is a double walled tube sampler with an inner linear removable.
• Sample is collected in inner liner.

Basic requirement of sampler for cohesive soil:

Let,

D₁ = Inner diameter of cutting edge

D₂ = Outer diameter of cutting edge

D₃ = Inner diameter of sampler tube

D₄ = Outer diameter of sampler tube

Basic requirement of sampler for cohesive soil are as follows

1. Area ratio (A_r)

• A_r = (D₂² – D₁²) * 100% / D₁²
• For obtaining good quality undisturbed sample, the area ratio should be less than 10%.

2. Inside clearance ratio (C_i)

• C_i = (D₃ – D₁)* 100% / D₁
• Reduce the friction between the soil sample and the sampler when soil enters the tube allowing elastic expansion of soil.
• For undisturbed sample: C_i = (0.5 to 3)%

3. Outside clearance ratio (C_o)

• C_o = (D₂ – D₄) * 100% / D₄
• Lies between (0 to 2)%
• For reducing driving force it must be minimum.

4. Recovery length ratio (L_r)

• L_r = L/H [where, L = Length of sampler & H = Depth of penetration of sampling tube]
• Condition:
• L_r = 1; Indicates a good recovery.
• L_r  < 1; Soil in sample is compressed.
• L_r > 1; Soil has swelled.
• It lies between (96 to 98)%

5. Inside wall friction

• Wall of sampler should be smooth and properly oiled.

6. Non – return value

• It should permit easy and quick escape of water and air when sample is driven.

1.3 Planning of exploration, number of bore holes, depth of exploration

Planning of exploration:

• A detailed study of the geographical condition of the area which includes collection of topographical and geographical maps.
• Collection of hydraulic condition such as water table fluctuation, flooding of site.
• Preparation of layout plan of project.
• Preparation of borehole layout plan.
• Marking on the layout plan for addition soil investigation if required.
• Preparation of specification and guideline for field execution.
• Preparation of specification and guideline for testing and collecting sample.

Number of bore holes:

• More number of borehole sunk more we will know about site condition and greater economy is achieved in foundation design.
• For small structure at least 2 or 3 bore holes should be shank.

Depth of exploration:

• Depth of boring depends upon the depth of soil affected by the load transmitted by foundation.
• Guideline regarding depth of boring are :

1.4 Field penetration test and their suitability

1. Standard penetration test

• Most commonly used for cohesion less soil.
• Split spoon sampler is used.
• This test is done to determine relative density.
• The sampler is driven into the soil by dropping hammer into the soil falling vertically through a height of 750 mm at the rate of 30 blows per minute.
• The number of hammer blows required to driven 150 mm of the sampler is counted. Again, the sampler is driven by 150 mm and the number of blows is recorded. Further the sampler is driven by 150 mm and the number blows is recorded.
• The number of blows is recorded for the last two 150 mm interval are added to give the SPT value.

Merit:

• Quick and simple to perform.
• Able to penetrate dense layer, gravel and fill.

Demerit:

• Not continuous.
• Sample obtained is disturbed.

SPT value correction:

a. Dilatancy correction

• Applied when the test is performed in fine or silty saturated sand.
• To reduce over estimate value of SPT.

The correction penetration number;

N^|_c = 15 + (N_R – 15)/2

If N_R ≤ 15, N_c = N_R

Where,

N_R = Recorded N- value

N_c = Corrected N-value

b. Overburden pressure correction

• Penetration resistance  of soil depends on over burden pressure.
• In deeper depth overburden pressure is high and its response to SPT test will better compare to the same soil at shallow depth.

Correction SPT- N value is

N_c = C_N * N^|_c

Where,

N_c = Corrected N value of overburden pressure

N^|_c = Observed N value

C_N = Correction factor = 0.77 log₁₀ (2000/ σ_o)

2. Static cone penetration test (SCPT)

• Widely used in place of SPT test for soft clay and silt.
• Standard cone is pushed into soil by applying force. For obtaining cone resistance cone is pushed downward at a steady rate. Now, both cone and sleeve are pushed into soil and combined resistance is determined.

∴ Resistance of sleeve = Combined resistance – Cone resistance

Merit:

• Simple and quick.
• Economical to perform.
• Help in identifying problem in soil.

Demerit:

• Soil sample is not obtained.
• Requires special equipment and skill manpower.

3. Dynamic cone penetration test (DCPT)

• If hard layer is found DCPT is done.
• The sampler is driven into the soil by dropping hammer into the soil falling vertically through a height of 750 mm at the rate of 30 blows per minute.
• The number of hammer blows required to driven 150 mm of the sampler is counted. Again, the sampler is driven by 150 mm and the number of blows is recorded. Further the sampler is driven by 150 mm and the number blows is recorded.
• The number of blows is recorded for the last two 150 mm interval are added to give the SPT value.

Merit:

• Doesn’t need borehole.
• Economical.

Demerit:

• Cannot be performed in cohesive soil.
• Not possible to determine mechanical properties of soil.

1.5 Ground – water observation

• The variation of ground water affect the soil characteristics such as shear strength.
• Important to find maximum and minimum water level for proper design of structure.
• In highly permeable soil depth of water table is measure by chalk coated tape.
• In low permeable soil depth of water table is measured by Casagrande piezometer.

1.6 Borehole logs

• Detailed record of boring operation and other tests carried out in the field.
• Provided information in bore log is useful to give information of soil type, consistency of soil and water table.

1.7 Site investigation report

• Result/ conclusion of the investigation, exploration and testing program.
• Report should be comprehensive, clear and to the point.
• Typical report includes following point:
• Introduction
• Borehole log
• Field and laboratory test result
• Analysis of data
• Recommendation
• Reference

References:

• Terzaghi, Karl and peck, R.B. John Wiley.(1967). Soil mechanics in engineering practice, New York.
• Arora K.R. (1997). Soil Mechanics and foundation engineering, India: Standard Publisher Distribution.

The post Site investigation and Soil exploration: Field penetration tests and their suitability appeared first on OnlineEngineeringNotes.

Purpose / Importance:

• To determine the type of foundation.
• To determine design parameter for the foundation such bearing capacity and allowable soil bearing pressure.
• To calculate potential settlement of foundation.
• To determine expansion potential at the site.
• To investigate the stability of slope and their effect on adjacent structure.
• To investigate possible way of improving the soil to increase the foundation bearing capacity.

Types of foundation:

A. Shallow foundation

• Width greater than its depth.
• Located just below the lower part of wall or column which it support.

Types of shallow foundation:

1. Strip / Continuous footing

• Provided for load bearing wall.
• L>B.

2. Spread / Isolated footing

• Circular, square or rectangular slab of uniform thickness.

3. Combined footing

• Supports two or more columns in row.
• Preferred in limited space.

4. Strap / Cantilever footing

• Two or more footing connected by beam.

5. Mat / Raft foundation

• Consist of large slab supporting number of column and walls.

B. Deep foundation

• Depth is greater than width.
• Distributes load from super-structure vertically rather than laterally.

Types of deep foundation:

1. Pile foundation

• Column made of wood, steel, concrete of RCC.
• Embedded into the ground to transmit the load of the structure to a hard stratum or compressed soil.

2. Pier foundation

• A cast insitu pile greater than 0.6 m diameter is termed as pier.
• Consists of cylindrical column of large diameter to support and transfer load.

3. Well foundation

• Well is a type of cassion.
• Suitable for soil containing large boulders.

1.2 Factors affecting choice of foundation

• Function of structure.
• Cost of foundation.
• Sub-surface condition of soil.
• Boundry criteria.
• Bearing capacity of soil.
• Types of load of super structure and other load acting on foundation.

1.3 Introduction to machine foundation

• Foundation provided below the super strucutre of a vibrating and rotating machine for installation is called machine foundation.
• Includes the studies of vibration of foundation soil system transmitted by wave energy.
• Used for supporting turbines, large electric motor and generator.
• Wave energy transmitted through the underlined soil from the foundation should not cause harmful effects to machine, structure of people.

1.4 Types of machine foundation

1. Block foundation

• Consists of a pedestal resting on a footing.
• It has large mass and smaller natural frequency.
• Provided for compressor and reciprocating engine.

2. Box or caisson’s foundation

• Use for lighter foundation.
• It has smaller mass and higher natural frequency.

3. Wall type foundation

• Consist of well-column and beam slab.
• Steam turbines are provided with wall type foundation.

1.5 Types of machine

1. High speed machine

• Turbo generator and rotary compressor fall in this category.
• Speed ranging from 3000 to 10000 rpm.

2. Low speed machine

• Compressor and reciprocating engine comes in this category.
• Speed is smaller than 600 rpm.

3. Impact type machine

• Produce impact loading.
• Speed is usually 60 to 150 blows per minute.

References:

• Terzaghi, Karl and peck, R.B. John Wiley.(1967). Soil mechanics in engineering practice, New York.
• Arora K.R. (1997). Soil Mechanics and foundation engineering, India: Standard Publisher Distribution.

The post Introduction to Foundation and Machine Foundation appeared first on OnlineEngineeringNotes.

Elements of lateral load resisting masonry system are:

• Shear wall: A structural panel that can resist lateral force acting on it.
• Gable band: Building having slopped roof i.e. truss construction.
• Roof band: Used in building with roof made of flat timber or CGI sheet.
• Lintel band: Horizontal member placed at top of the opening like door and window to support unsupported wall above it.
• Sill band: Horizontal member placed at bottom of the opening to support load of opening frame.
• Tie beam: Horizontal beam that ties two structural member from separating.

1.2 In – plane and out of plane behavior of masonry wall

• Inplane and out of plane behavior of masonry wall are also called the failure mechanism of walls.

In – plane failure:

• Occurs when masonry element get pushed in the direction of the plane of wall.

Modes:

a. Sliding shear:

• Occurs when structure has low shear resistance than flexural strength.

b. Shear failure:

• An internal splitting force caused by two force acting in opposite direction.

c. Bending failure:

• Occur when tensile strength is equal or greater than ultimate strength of structure.

Out plane failure:

• Occurs when masonry element get pushed in the direction perpendicular to the wall.

Mode:

a. Topping failure:

• Forward rotation or movement of mass of structure due to vertical cracks.

b. Over turning failure:

• Occurs when movement equilibrium is not satisfied.

1.3 Failure behavior of masonry wall in lateral loads

• During lateral loading some portion of masonry walls undergo in tension and ultimately fails at tension zone.
• The failure modes depends upon the type of construction, amount and size of opening.
• The failure in unreinforced masonry building is due to structural defects such as lack of proper joint and large unsupported wall length.

The various failure in masonry structure:

1. Diagonal shear cracks.
2. Horizontal shear cracks.
3. Bending cracks at lintels and feet.
4. Bending cracks at corners.
5. Bending crack at gable.
6. Peeling of plaster.

1.4 Analysis for stresses on masonry wall under lateral loads

• When wall is subjected to lateral load such as wind, earthquake etc. bending will occur depending on support condition.

Consider a wall subjected to uniformly distributed vertical load P at centre line in one axis as shown in figure. The force is caused by self weight of wall, other external loading and applied uniform compressive stress across the section.

Compressive stress due to load P = P/A ———(i)

Again,

Consider lateral load ‘w’ KN/m² applied to the section of wall and corresponding stress is given by

     σ_b / y = M / I

or,  σ_b = M*y / I

or,  σ_b = M / Z [∴ I/y = Z]

where,

σ_b = Bending stress

M = Maximum bending moment

I = M.O.I about length of wall

Z = Section modulus

y = Distance of considered layer from NA

1.5 Ductile behavior of reinforced and unreinforced masonry structure

• Capacity of an element of structure to undergo large deformation without failure.
• Masonry is brittle in nature.
• Unreinforced masonry cannot withstand tension so cracks develops.
• Inplane and out plane failure is also due to ductility of masonry.
• To improve ductility reinforcing bars are embedded in the masonry to resist seismic force.

1.6 Compressive strength of masonry unit and masonry walls

Compressive strength of masonry units:

Apparatus required: Universal testing machine

Specimen: At least three number of masonry unit

Procedure:

• Place the specimen in flat face between the plates of testing machine.
• Applying axial load at a uniform rate of 140 kg/cm² per minute till failure occurs.
• Maximum failure is noted.

σ_c = Maximum load of failure/ Average contact area

Compressive strength of masonry walls:

Apparatus required: Universal testing machine

Specimen: At least three number of brick with certain bond type

Procedure:

• Place the specimen in flat face between the plates of testing machine.
• Applying axial load at a uniform rate of 140 kg/cm² per minute till failure occurs.
• Maximum failure is noted.

σ_c = Maximum load of failure/ Average contact area

1.7 Diagonal shear test

• In load bearing masonry wall shear wall carry vertical load and resist lateral load when combined loading creates tensile stress the tensile strength of masonry is exceeded leading tensile cracking.
• To evaluate masonry shear strength and shear elastic modulus diagonal test is performed on rectangular masonry specimen.
• In diagonal shear test a 1.2 * 1.2 m square section of wall is placed between the compressor to determine shear strength and shear modulus.
• Diagonal shear stress can be calculated by

τ = P / A * 2^1/2

where,

P = Applied load

A = Average cross section area of specimen

1.8 Non – destructive test

1. Elastic wave tomography:

• Used for locating shallow cracks and voids.
• Based on the principle of heat transfer i.e. conduction and radiation.
• Allows rapid mapping of internal condition.
• Material with no voids, gaps or cracks are more thermally conductive than material with moisture content.

2. Flat – jack test:

• Used to analyze and evaluate existing masonry structure.
• Uses small thin hydraulic jack to apply a force to a section of an existing masonry wall and measuring device determine the resulting displacement of masonry.
• Measure shear strength of structure.
• Measure compressive strength.

Types of flat jack test:

a. Single flat test or insitu shear test

b. Double flat jack test or insitu deformability test

3. Push shear test:

• Firstly, the brick, mortar are removed from test location. Also joint on opposite side also removed.
• Mortar joint above and below are not disturbed.
• Now, hydraulic ram is inserted along with pressure gauge to measure actual strength.
• A block is placed in order to distribute load uniformly and loading is done till cracking or movement is observed.
• Force at cracking or movement is noted to develop force deflection plot.

References:

• Dayaratnam, P. Brick and reinforced brick structure.
• Neville, A.M. Properties of Concrete. England: Pearson Education Limited.
• Hendry, A.W., Sinha, B.P. & Davies, S.R. Design of Masonry Structure. London: E & FN Spon.

The post Masonry Walls Under Lateral Loads and Testing of Masonry Elements appeared first on OnlineEngineeringNotes.

• A masonry structure is one made by joining (bonding) multiple number of building blocks like brick, stone, block etc. usually with cohesive material called mortar. The mortar may be mud mortar, lime mortar, cement mortar etc.

Merits:

• They are non – combustible so improves fine protective of building.
• Environment friendly.
• Economic.
• Use of locally available material.
• Most of the wall does not require painting.

Demerits:

• Extreme weather causes degradation of masonry wall.
• Low tensile strength.
• Problem in large opening.
• Due to heavy weight large foundation is required. Also cracking and settlement may occur.

Types of masonry unit:

1. Brick masonry:

• Highly durable form of construction.
• Build by placing bricks in mortar in a systematic manner to construct solid mass which can withstand external load.

2. Stone masonry:

• Use of stone and mortar.
• Used for building foundation, floor and retaining wall etc.

3. Concrete block:

• Hollow building unit of concrete.

4. Glass block:

• Fixed together to form complete wall by several method.

5. AAC (Autoclaved aerated concrete) block:

• Light weight building block ensure better durability and improves sound and heat insulation.

Types of brick wall:

a. Stretcher bond:

• Formed when stretcher of bricks are laid along the face of wall.
• Used in partion wall.

b. Header bond:

• Formed when head of bricks are laid along the face of wall.
• ¾ bat is provided in each alternative course in corner.
• Unsuitable for load bearing structure.

c. English bond:

• Consists of alternative course of headers and stretchers.
• Queen closer after first header in each heading course.

d. Flemish bond:

• Each course is comprised of alternative headers and stretchers.
• Every alternative course starts with header at corner.

e. Zigzag  bond:

• Laid in zigzag fashion.
• Used in brick flooring.

1.2 Types of masonry structure

1. Load bearing and non – load bearing masonry.

Load bearing masonry:

• Oldest and mostly used technique.
• Every wall elements carries load to the foundation which is transferred to the ground.
• Mainly used to construct residential building.

Merits:

• High fire resistant.
• Fabrication is not required.
• Aesthetically attractive.

Demerits:

• Performs bad during earthquake.
• More manpower required during construction.
• Construction is slow.

Types of load bearing masonry:

• Precast concrete wall
• Retaining wall
• Brick wall
• Stone wall

Non – load bearing masonry:

• Walls carry only their own weight.
• Used for partion wall.
• Built lighter to reduce the dead  load of structure.
• Can easily be removed without endangering the safety of the building.

Types of non – load bearing masonry:

• Hollow concrete brick wall
• Façade brick wall
• Hollow brick wall
• Brick wall

2. Reinforced and unreinforced masonry

Reinforced masonry:

• A construction system where steel bars, reinforced concrete bands, bamboo, timber etc are embedded in the mortar or placed in the holes and filled with concrete.
• Increases tensile as well as compressive strength.

Classification:

a. Reinforced hollow unit masonry:

• Vertical reinforcement is inserted inside brick or block and filled with concrete or grout.

b. Reinforced grouted cavity masonry:

• Consist of two leaves of masonry units separated by the cavity into which the vertical and horizontal reinforcement is placed and grouted with either concrete infill or grout.

c. Reinforced packet type wall:

• Pockets containing vertical bars are filled with grout.

Unreinforced masonry:

• Reinforcing bars is not placed.
• Likely to be damaged during earthquake.
• Mortar holding masonry is weak.

1.3 Properties and strength of cement mortar

• Cement mortar is a homogenous mixture of sand, cement and water in suitable proportion.

Properties:

• Should be easily workable.
• Should be durable.
• Should not affect durability of other materials.
• Should retain mixed water for longer period of time.
• Should have sufficient strength to handle the load of structure.

Strength:

• Compressive strength of cement mortar after curing 28 days is 33 N/mm² to 53 N/mm².

1.4 Introduction to codal provision (NBC 109) and guideline (NBC 202)

• In the past there was no code for designing masonry construction and at that time design was based on thumb rule. The thickness of wall were found to be very big and uneconomical.

Code design of masonry are:

• IS 1905: Code for practice for structural use of unreinforced masonry.
• NBC 202:2015: Guideline on load bearing masonry.
• NBC 109:1994: Code for use of unreinforced masonry.

1.5 Bonding elements in masonry

• Bonding is the systematic arrangement of bricks or other building units composing a wall or structure in such a way as to ensure stability and strength.

Types of bonding elements in masonry are:

a. Bond – stone:

• Large stone which passes through a wall from one side to the other to lock the layers of the wall together and reinforce the structure.

b. Bands:

• Provided to hold a masonry building as a single unit by typing all the wall together.

c. Dowels:

• Provided to transfer load without restricting horizontal joint movement due to temperature and moisture expansion and contraction in the concrete slab.

References:

• Dayaratnam, P. Brick and reinforced brick structure.
• Neville, A.M. Properties of Concrete. England: Pearson Education Limited.
• Hendry, A.W., Sinha, B.P. & Davies, S.R. Design of Masonry Structure. London: E & FN Spon.

The post Introduction to Masonry Structure and Design of Masonry Walls for Gravity Loads appeared first on OnlineEngineeringNotes.

1. Tensile strength:

• Due to brittle nature of concrete it is very weak in tension.
• Concrete develops cracks when subjected to tensile force. So it important to determine the tensile strength of concrete.

Tensile strength (F_ct) = 0.35 (F_ck)^1/2

Where,

F_ck = Characteristics compressive strength

2. Compressive strength:

• Concrete has high compressive strength.
• Most of the concrete structure are designed by adopting the value of compressive strength.

3. Shear strength:

• Occurs to the combination of tensile and compressive stress or due to the application of torsion.
• Shear strength of concrete is about 12% of compressive strength of concrete.

4. Bond strength:

• The resistance to slip of the steel reinforcement bars which are embedded in concrete.
• Higher the grade of concrete higher the bond strength.

1.2 Compressive, tensile and bond strength tests

Compressive strength tests:

1. Cube test:

• Specimen of 150 mm * 150 mm * 150 mm cube is used.
• The cube filled in three layers and well compacted.
• The top is made smooth and the finished surface is left undisturbed for 24 hours at room temperature.
• Then the mould is removed and the specimen is stored in water for curing usually up to 28 days.
• The testing of specimen is taken at 1,3,7,14,28,90 and 365 days.
• The test is performed by standard uniaxial compression test and at each time, minimum three sample are tested.

Compressive strength of concrete = Force at failure / Area

2. Cylinder test:

• The test is carried out using concrete cylinder of diameter 150 mm and 300mm height.
• The cylinder is filled in three layer and well compacted.
• Cube strength is higher than cylinder strength.

Tensile strength test:

• It is very complex to apply uniaxial tension to a concrete specimen so the tensile strength of concrete is determined by two test.

The test which are performed for tensile strength test are as follows:

1. Flexural test:

• Evaluates the tensile strength of concrete indirectly.
• Test the ability of unreinforced concrete beam or slab to withstand failure in bending.

2. Splitting test:

• Method of determining tensile strength of concrete using a cylinder which splits across vertical diameter.
• Concrete cylinder is placed horizontally.

Horizontal tensile strength (F_st) = 2P/ πLD

Where,

P = Applied load

D = Diameter of cylinder

L = Length of cylinder

Bond strength test:

• Bond test can be done by pullout test.

Pullout test:

• Destructive technique that involves drilling a hole into the hardened concrete and inserting oversized screw into that hole.

1.3 Non – destructive tests

• Test which are performed without destruction of the sample are known as non – destructive test.

Objective:

• To determine the strength of concrete.
• To determine cracks in concrete.
• To determine permeability of concrete.
• To determine the thickness of concrete layer.

Merits:

• Less wastage of material.
• Accident prevention.

Demerits:

• Expensive.
• Dangerous (Radiation hazards)

Method of non – destructive test are:

1. Rebound hammer test:

• Done to estimate the compressive strength of concrete.
• Also known as Schmidt hammer test.
• It is a device used to measure the elastic properties or strength of concrete.

Merits:

• Easy to carry out.
• Cheap.
• Skilled manpower not required.

Demerits:

• Interpretation of data is difficult.
• Only measure strength of concrete close to the surface.

2. Ultrasonic pulse velocity method:

• Used to determine the integrity and quality of concrete by measuring the speed and attenuation of ultrasonic wave passing through the element being tested.
• There are three ways of measuring pulse velocity through concrete. They are as follows:

a. Direct transmission

b. Indirect transmission

c. Surface transmission

1.4 Variability of concrete strength and acceptance criteria.

Variability of concrete strength:

• Strength concrete varies from batch to batch over a period of time.

Factors affecting variation of concrete strength:

• Quality of raw material.
• W/C ratio.
• Age of concrete.
• Compaction of concrete.
• Curing.

Acceptance criteria:

a. Compressive strength:

• The mean strength determined from any group of four non – overlapping consecutive test results, complied with the appropriate limits col 2 of table.
• Any individual test results complies with the appropriate limits in col 3 of table.

b. Flexural strength:

• Mean compressive strength of four consecutive test results must be more than equal to characteristic strength of concrete +3 N/mm².
• Any test results is not less than specified characteristic strength -0.3 N/mm².

1.5 Quality control and quality assurance

Quality control:

• Quality means degree of excellence.
• Good design is not sufficient but its actual implementation is required for fully quality work and good performance of structure.

Quality can be controlled by:

• Appropriate mixing.
• Proper compaction.
• Correct placing.
• Adequate curing.

Quality assurance:

• Systematic process of determining whether the concrete structure meets specified requirement is called quality assurance.

References:

• Dayaratnam, P. Brick and reinforced brick structure.
• Neville, A.M. Properties of Concrete. England: Pearson Education Limited.
• Hendry, A.W., Sinha, B.P. & Davies, S.R. Design of Masonry Structure. London: E & FN Spon.

The post Testing of concrete and quality control: Variability of concrete strength and acceptance criteria and Non – destructive tests appeared first on OnlineEngineeringNotes.

• Mixture made with light weight coarse aggregate such as shale, clay or silt giving low density.
• The density of light weight aggregate is less than 1200 kg/m³.

Merits:

• Minimize the dead load of the building.
• Simple to handle which decrease the cost of transportation.
• Enhances workability.
• Thermal conductivity decreases.
• Stronger and more durable.

Demerits:

• Sensitive to amount of water used in mix.
• Due to porosity and angular aggregate placing and finishing is difficult.

1.2 Aerated concrete

• Light weight concrete prepared by introducing large volume of air into the slurry of cement (with or without lime), fine sand and water.
• No coarse aggregate is used.
• Also known as gas/foam/ cellular concrete.

Merits:

• Low density of 800 kg/m³.
• Low thermal conductivity.
• Ensure sound proofing ten times better brick thickness.
• Fire resistant.
• Environmentally friendly.

Demerits:

• Production cost is high.
• Extra care during manufacture.
• Strength reduce in wet condition.

1.3 No – fines concrete

• Obtained by eliminating fine aggregate in mix concrete.
• There is no voids in coarse aggregate during making of no fines concrete.

Merits:

• Density is low.
• No seggregation is found.
• Shrinkage is lower than normal concrete.
• Formwork can be removed earlier.
• Gives better and attractive appearance.

Demerits:

• Low strength.
• Cannot be used in reinforced concrete structure.
• Consistency cannot be measured.

1.4 High density concrete

• Concrete with high density greater than 3360 kg/m³.
• Used for radiation shielding.

Merits:

• Easy to construct.
• Good chemical resistance.
• Cheap.
• Offers more strength.

Demerits:

• More space required.
• Weight of concrete is high.

1.5 Fiber reinforced concrete

• Produce by uniformly dispersing suitable type of discontinous and discrete fibre in mixture of concrete.

Merits:

• Improves impact strength of concrete.
• Resistance to plastic shrinkage.
• Reduce seggregation.

Demerits:

• Lack of tensile strength.
• Not environmentally friendly.

1.6 Self compacting concrete

• Ability to flow under its own weight to fill the required space or formwork completely and produce dense and homogenous material without need of vibrating compaction.

Merits:

• Faster construction and requires less manpower.
• No need to use vibrator.
• Economic.
• No seggregation and bleeding.

Demerits:

• Highly skilled worker required.
• More costly than other conventional concrete.

1.7 Shotcrete

• Concrete with small sized coarse aggregate is conveyed through a nose and pneumatically projected at high velocity onto a surface as a construction technique.
• Used in curved surface.
• Best for construction of tunnel, domes etc.

Merits:

• Reduce manpower.
• Economical.
• Easily control w/c ratio.
• Maintence cost is less.

Demerits:

• Material wastage high in compare to conventional concrete method.
• High skill manpower required.

1.8 Introduction to nominal mix and design mix

Nominal  mix:

• Nominal mix specifies the fix proportion of cement, sand and aggregate.
• Ingredient of concrete are mixed on the basis of volume.
• Used for M20 or less strength of concrete.
• Nominal mix, proportion and use are given below:

Design mix:

• Process to prepare concrete by testing all necessary properties.
• Used for M25 & above grade of cement.

1.9 Probabilistic concept in mix design approach

• The strength of concrete depends upon the quality of material and the constructional methods being used.
• Variability in quality or construction method cause variation in strength.
• The strength of concrete is determined through cube specimen varies with the size of the cube.
• The strength of specimen increases with decrease in size.
• If large number of cube strength test result are plotted on histrogram the result are found to follow bell shaped curve known as normal distribution curve.

From the curve,

Mean strength (F_m) = ΣX/N

Standard deviation (S) = [Σ(x – x̄)² / (n  – 1)]^1/2

Where,

N or n = Number of test of specimen

Characteristics strength:

• Defined as the level of strength below which a specified proportion of all valid test results is expected to fail.

Characteristics strength (F_ck)

F_ck = F_m – 1.65S

Coefficeint of variation (V):

V = (S/F_m) * 100

References:

• Dayaratnam, P. Brick and reinforced brick structure.
• Neville, A.M. Properties of Concrete. England: Pearson Education Limited.
• Hendry, A.W., Sinha, B.P. & Davies, S.R. Design of Masonry Structure. London: E & FN Spon.

The post Introduction to Special Type of Concretes and Mix Design of Concrete: Probabilistic concept in mix design approach appeared first on OnlineEngineeringNotes.

 Deformation of hardened concrete:

Following strains are responsible for the deformation of concrete:

a. Elastic strain:

• Instantaneous deformation that occurs when an external stress is first applied.

b. Shrinkage strain:

• Deformation that occurs due to the loss of moisture from concrete.

c. Creep strain:

• Deformation that occurs in the direction of force applied.

d. Thermal strain:

• Deformation due to change in temperature.

Modulus of elasticity:

• Defined as the slope of the relationship between stress and strain.
• It is a measure of stiffness or resistance to deformation of a material.
• Higher modulus indicates stiffer concrete with lesser deformation.

Types of modulus of elasticity:

1. Static modulus of elasticity:

• It is the value of modulus of elasticity determined by actual loading of concrete.

Types of static modulus of elasticity:

a. Initial tangent modulus:

• Given by the slope of a line drawn tangent to the stress- strain curve at the origin.

       b. Tangent modulus:

• Given by the slope of a line drawn tangent to the stress – strain curve at the origin.

       c. Secant modulus:

• Given by the slope of a secant joining origin and a fixed point on curve.

d. Chord modulus:

• Given by the slope of a line drawn between two point on the stress strain curve.

2. Dynamic modulus of elasticity:

• Elasticity of concrete under dynamic loads such as longitudinal and flexural vibration.

3. Flexural modulus of elasticity:

• Ability of a material to bend.

1.2 Creep, shrinkage and thermal expansion

Creep:

• Defined as gradual increase in strain (deformation) under sustained stress (or loads).
• Dependent on quality of cement paste and age of concrete.
• The amount of creep is expressed in terms of creep coefficient.

Creep coefficient (C_c) = Creep strain / Elastic strain

Factors affecting creep:

• Higher w/c ratio higher the creep.
• The stiffer the aggregate the smaller the creep.
• More aggregate fraction less is the creep.
• Increase in temperature leads to increase in creep.

Shrinkage:

• Reduction in the volume of a freshly hardened concrete under the condition of ambient temperature and humidity.
• It is caused by loss of water through evaporation or by hydration of cement.

Types:

1. Plastic shrinkage:

• Occurs due to the loss of water by evaporation from freshly prepared concrete while cement paste is plastic.
• At larger cement content of mix, plastic shrinkage of concrete is higher.

2. Drying shrinkage:

• Occurs due to the loss of water by evaporation from freshly hardened concrete exposed to air.

3. Autogenous shrinkage:

• Occurs due to loss of water by self –  desiccation of concrete during hydration.

4. Carbonate shrinkage:

• Occurs when the concrete is exposed to air containing carbon dioxide.

5. Thermal shrinkage:

• Occurs due to excessive fall in temperature.

Factors affecting shrinkage:

• Higher the w/c ratio larger the shrinkage.
• Low relative humidity more the shrinkage.
• The lighter the aggregate more the shrinkage.

Thermal expansion:

• Concrete expands on increasing the temperature.
• The coefficient of thermal expansion depends upon nature of cement, aggregate, relative humidity and size of concrete. In normal condition the expansion mainly depends upon aggregate.

1.3 Fatigue, impact and cyclic loading

Fatigue:

• Failure of a material by fracture when it is subjected to a cyclic stress.
• Fatigue is the result of repeated application of stress to the concrete.

Two types of failure in fatigue takes place in concrete are:

a. Failure occurs in sustained load (slowly increasing load)

b. Failure occurs under cyclic or repeated loading.

• For constant load of alternating stress, the fatigue strength decreases as the number of cycle increases.

Log N = (1 – F_max/F_c)/ β(1 – F_min/F_c)

Where,

F_max = Maximum stress in a cycle

F_min =  Minimum stress in a cycle

F_c = Strength under static loading

Β = 0.085

Impact and cyclic loading:

• The load that is applied suddenly at short time interval is called impact load. The strength that shows impact load is called impact strength.
• Impact strength increases with:

a. Increase in rate of loading.

b. Increase in tensile strength.

c. Decrease in aggregate strength.

• The CEB – FIP mode code (1990) recommends following relation for impact strength.

 F_c,_imp = f_c * (σ_s / σ_o) ^α
where,

F_c,_imp = Impact compressive strength

f_c = Compressive strength of concrete

σ_s = Impact strength rate

σ_o = 1 MPa

α = 1 / [5 + 9 * (f_c / f_co)]

1.4 Effect of porosity, water – cement ratio and aggregate size

Effect of porosity:

• Primary factor that governs the strength of concrete.
• Strength of concrete decreases with the increase in porosity.
• Permeability of concrete increase with increase in porosity of concrete.
• Factors like w/c ratio, degree of hydration, air content, mineral admixture, aggregates affects concrete porosity.
• Increase in w/c ratio increase the porosity.

Effect of water content cement ratio:

• W/C ratio is an index of strength of concrete. The strength of cement paste increases with increase in cement concrete and decrease in water content and air content.
• High w/c ratio increase the porosity and permeability of concrete and reduce its durability.
• From Abram’s law it is found that the cement requires about 1/5 to 1/4  of its weight of water to hydrate completely.

Mathematically,

C = A /B^x

Where,

C = Compressive strength of concrete

A, B = Empirical constant

x = w/c ratio

Effects of aggregate size:

• Aggregate is an important factor affecting the concrete strength. The most important properties of concrete are shape, texture and size of aggregate.
• Large size aggregate reduce specific surface area of aggregate which leads to reduction in bond.
• If constant workability is maintained, strength will increase with cement content.
• High strength or rich mix concrete is adversely affected by the use of large size aggregate. When large aggregate are used due to internal bleeding in transion zone it will become much weak by developing micro cracks with lower compressive strength.

1.5 Durability of concrete

• The ability of concrete to resist weathering action, chemical attack and abrasion while maintaing its desired engineering properties.

Factors that affect durability of concrete:

• W/C ratio
• Compaction
• Permeability
• Temperature
• Aggregate
• Porosity

References:

• Dayaratnam, P. Brick and reinforced brick structure.
• Neville, A.M. Properties of Concrete. England: Pearson Education Limited.
• Hendry, A.W., Sinha, B.P. & Davies, S.R. Design of Masonry Structure. London: E & FN Spon.

The post Properties of Hardened Concrete: Deformation of hardened concrete, moduli of elasticity & Fatigue, impact and cyclic loading appeared first on OnlineEngineeringNotes.