Too coarse aggregate results in hardness, segregation and bleeding and too fine aggregate requires too large w/c ratio for adequate workability.

Exploring Concrete Fundamentals: 

Aggregates, ASR, and Structural Case Studies

 

Too coarse aggregate results in hardness, segregation and bleeding and too fine aggregate requires too large w/c ratio for adequate work-ability.

 

The statement is highlighting the importance of the proper gradation of aggregates in concrete mixtures, specifically coarse and fine aggregates, and its impact on various properties of concrete. Let's break it down:

1. "Too coarse aggregate results in hardness, segregation, and bleeding":

   • Hardness: Excessively large coarse aggregates can make the concrete mixture difficult to work with, leading to a concrete mix that is harder to place and compact.
   • Segregation: Coarse aggregates that are too large may settle at the bottom during the mixing and transportation process, causing uneven distribution of aggregates and resulting in a non-uniform concrete mixture.
   • Bleeding: This refers to the separation of water from the concrete mix, where excess water tends to rise to the surface. Coarse aggregates that are too large can contribute to bleeding issues.

    

   Example: Imagine a construction project where the concrete mix contains very large pebbles as coarse aggregates. The resulting concrete might be difficult to pump, place, and finish due to the challenges posed by the excessively coarse aggregates.
    

2. "Too fine aggregate requires too large w/c ratio for adequate workability":

   • W/C ratio (Water-to-Cement ratio): The water-to-cement ratio is a critical factor in concrete mix design. Too much water is generally undesirable as it can affect the strength and durability of concrete.
   • Adequate workability: Workability refers to how easily the concrete can be mixed, placed, and finished. If the fine aggregate content is too high, it may require more water to maintain workability.

    

   Example: Consider a concrete mix with an excess of fine sand as the fine aggregate. To maintain workability, a higher water-to-cement ratio might be needed. This can lead to a weaker and less durable concrete, impacting the overall performance of the structure.
    
    

   Negligence in Considering aggregate properties

    

There have been instances where negligence in considering aggregate properties led to issues and damages in structures. One notable example is the case of the Alamillo Bridge in Seville, Spain.

 

 Example of Negligence - Alamillo Bridge in Seville, Spain

• The Alamillo Bridge, designed by architect Santiago Calatrava and completed in 1992, features a distinctive asymmetrical design with a single leaning pylon and cables supporting the bridge deck. The bridge experienced structural problems, including cracking, which were attributed to issues with the concrete mix.

 

Negligence and Consequences:

• Aggregate Issues: It was found that the concrete mix used for the bridge had a high percentage of reactive silica in the aggregates, leading to alkali-silica reaction (ASR).
• ASR Impact: ASR is a chemical reaction between alkaline cement and reactive silica in certain aggregates, resulting in the formation of a gel. This gel can cause expansion and cracking in concrete, compromising its structural integrity.
  

Consequences of Negligence:

• Cracking: The alkali-silica reaction caused significant cracking in the concrete elements of the bridge, affecting its structural stability.
• Structural Repairs: Extensive repairs were required to address the damages, leading to additional costs and efforts.

This example underscores the importance of carefully considering aggregate properties and potential reactivity in concrete mix designs. Neglecting such factors can lead to serious structural issues and the need for costly repairs. In this case, a more thorough evaluation of the aggregates' properties could have prevented or mitigated the alkali-silica reaction and the subsequent damage to the Alamillo Bridge.

 

Studying examples like the Alamillo Bridge provides invaluable lessons, emphasizing the critical importance of meticulously analyzing aggregate properties and avoiding potential issues such as the Alkali-Silica Reaction.

Alamillo Bridge and ASR: Case Study

1. Design and Construction:

   • The Alamillo Bridge in Seville, Spain, was designed by Santiago Calatrava and completed in 1992. Its distinctive design features a single leaning pylon and a cable-stayed bridge deck.
   • During construction, the concrete mix used for the bridge included aggregates with a high percentage of reactive silica.

    

2. Alkali-Silica Reaction (ASR):

   • Nature of ASR: ASR is a chemical reaction that occurs in concrete when certain types of reactive silica present in aggregates react with the alkaline substances in cement.
   • Formation of Gel: The reaction results in the formation of a gel-like substance within the concrete. This gel can absorb water and expand, leading to the development of internal pressure.

    

3. Consequences of ASR:

   • Cracking: The expansion caused by the ASR gel exerts pressure on the concrete, leading to the development of cracks. These cracks compromise the structural integrity of the concrete elements.
   • Reduced Durability: The continuous expansion and contraction due to ASR can result in a loss of durability and overall structural performance.

    

4. Identification of Issues:

   • Crack Formation: Over time, the Alamillo Bridge exhibited visible cracks in its concrete elements, signaling the presence of structural issues.
   • Investigation: Detailed investigations were conducted to determine the cause of the cracks, leading to the identification of the alkali-silica reaction as a primary factor.

    

5. Mitigation and Repairs:

   • Repairs Needed: To address the damages caused by ASR, extensive repairs were required. This involved repairing and reinforcing the affected concrete elements.
   • Costs and Delays: The repairs incurred significant additional costs and delays in the project timeline.

    

6. Lessons Learned:

   • Importance of Aggregate Selection: The Alamillo Bridge serves as a cautionary example of the critical role that aggregate selection plays in concrete mix design.
   • Avoidance of Reactive Aggregates: The experience emphasizes the importance of avoiding aggregates with high reactivity, especially reactive silica, to prevent detrimental effects like ASR.

    

In summary, the Alamillo Bridge case illustrates how neglecting the properties of aggregates, specifically the potential for alkali-silica reaction, can lead to structural issues, compromising the integrity of a concrete structure. The example underscores the need for meticulous consideration of aggregate properties in concrete mix design to ensure the long-term durability and performance of structures.

 

 

Understanding Alkali-Silica Reaction (ASR) is crucial for gaining comprehensive insights into the behavior of concrete, cement, and mortar, as well as the formation and long-term performance of structures.

The Alkali-Silica Reaction (ASR)

The Alkali-Silica Reaction (ASR) is a chemical reaction that can occur in concrete when certain types of reactive silica present in aggregates react with the alkaline substances in cement. Here's a more detailed explanation of ASR:

1. Ingredients Involved:

   • Silica in Aggregates: Aggregates, which are the inert granular materials (such as sand, gravel, or crushed stone) in concrete, may contain certain forms of silica minerals.
   • Alkali in Cement: Cement contains alkali compounds, such as sodium and potassium oxides.

2. Initiation of ASR:

   • Contact Between Silica and Alkali: When concrete is mixed, the alkaline cement comes into contact with the silica present in the aggregates.
   • Formation of ASR Gel: In the presence of moisture, a chemical reaction occurs between the reactive silica and the alkali. This reaction forms a gel-like substance, commonly referred to as ASR gel.

3. Characteristics of ASR Gel:

   • Hygroscopic Nature: The ASR gel is hygroscopic, meaning it can absorb and retain water.
   • Expansive Behavior: The gel expands as it absorbs water, creating internal pressure within the concrete.

4. Effects of ASR:

   • Crack Formation: The internal pressure generated by the expanding ASR gel can lead to the development of cracks in the affected concrete.
   • Loss of Strength and Durability: Continuous expansion and contraction due to ASR can result in a gradual loss of concrete strength and durability over time.

5. Visual Indicators:

   • Cracking Patterns: ASR-induced cracks typically exhibit distinctive map-like patterns on concrete surfaces.
   • Location of Cracks: Cracks often form in areas with high moisture exposure, as moisture is essential for the ASR reaction to occur.

6. Prevention and Mitigation:

   • Aggregate Selection: One of the primary methods to prevent ASR is to carefully select aggregates with low reactivity during the concrete mix design process.
   • Use of Supplementary Cementitious Materials: The addition of supplementary cementitious materials, such as fly ash or silica fume, can help mitigate the effects of ASR by reducing the availability of alkalis in the concrete.

Understanding ASR is crucial in the context of concrete durability and structural performance. Proper aggregate selection and mix design considerations play a pivotal role in preventing or mitigating the detrimental effects of ASR, ensuring the long-term stability of concrete structures.

 

Such case studies underscore the need for a thorough understanding of concrete behavior, aggregate selection, and mix design to ensure the structural integrity and durability of construction projects.

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Estimation, Costing and Construction Management - Civil Engineering

Estimation, Costing and Construction management 

Quick Revision Civil Engineering

 

1. Straight line method: 

• This assumes that the loss in the value of the property is same every year and at the end of its useful life it is equal to its scrap value.

2. Constant percentage method: 

• This assumes that thew property loses it value by a constant percentage of its value at the begining of each year. (n = life of machine)

Annual Depreciation=`[1−(Scrapvalue/originalcost)^n]`

The preparations of a detailed construction estimate consist of working out quantities of various items of work and then determine the cost of each item. This is prepared in two stages.

• 1. Details of measurements and calculation of quantities
• 2. Abstract of Estimated Cost
• In the first stage, the quantity, availability, and transportation of materials parameters is being analyzed.

The main function of an abstract of the estimate are as follows:

• i) The total estimated cost and the different items of works are required to complete a project can be known.
• ii) This is the basis on which percentage rate tenders are called after excluding the amounts for contingency and work-charged establishment.
• iii) This is a part of the tender document so as a contractor can arrive at his own rates from the schedule of work described in the description column.
• iv) This is the basis on which bills are prepared for payment.
• v) Comparative costs of different items of works can be known.

The capacity of doing work by an artesian or skilled labour in the form of quantity of work per day is known as out turn of the labour

Particulars of Item	Expected out-turn (m3)
Cement concrete (1 : 2 : 4)	5.0
Lime concrete in foundation	8.50
Reinforced Brick work	1.00
R.C.C work	3.00
Brickwork in lime or cement mortar in foundation and Plinth	1.25

Lead 

• The distance between the source of availability of material and the construction site is known as Lead and is measured in km.
• The cost of conveyance of material depends on lead.
• The environment lead on the metalled roads are arrived by multiplying by a factor as follows:
• a) For Sandy tracks – Lead × 1.4
• b) For metal tracks – Lead × 1.0
• c) For cartze tracks – Lead × 1.1

• Wet Qty. of concrete = Area × thickness
• Dry vol. of concrete = 1.54 × Wet volume of concrete
• No. of cement Bags = Cement Qty/0.035

Particulars of items	Units of measurements
Well sinking, pile driving, Dag-belling, Grouting of cracks or joints, Supply of pipes, Skirting, cornice	Meters
Plastering, pointing, Dado, White Washing, distempering, painting, polishing, coal tarring, removing of paint	Square meters
Tile roof, slate roofing, timber roofing, Ceiling, centering and shuttering, Damp proof course, Turfing or lining of canal, surface dressing or leveling, jail work or Jafri work, Woodwork indoors and shutters, sawing of timber, woodwork in partition and plywood.	Square meters
Boring holes in iron, painting letters, and figures, ornamental pillar caps, cleaning flues, cotton cords in skylight, Easing doors and windows, Fixing doors and windows	Numbers
Earthwork in excavation, puddling, Quarrying of stones, concreting, brickwork in the foundation, stone masonry	Cubic meters
Rolled steel joists, steel reinforcement bars, binding of steel reinforcement, fabrication and hoisting of steelwork	Quintals

Types of Estimage

Preliminary Estimate

It is an approximate estimate and prepared by owner itself before the actual award of work to any agency.

Cube Rate Estimate

It is an approximate estimate and prepared by calculating the cubical content of building by multiplying its length, breadth and height.

Detailed Estimate

It is the accurate estimate prepared by working out quantities of each items of work. 

It is prepared in two stages: 

• 1. Details of measurements and calculation of quantities and 
• 2. Abstract of Estimate.

Revised Estimate

It is prepared when original sanctioned estimate is likely to exceed more than 5%.

Supplementary Estimate

It is the fresh detailed estimate of the additional works in addition to the original estimate. It is required when further development is required during the progress of work.

Culverts

Culverts are usually included in the road estimate on the basis of cost per running meter of the span.

Earthwork

• Earthwork is measured in cubic meter for the estimation purposes. The length, breadth and depth shall be measured to get the cubic content.
• Measure of excavation or trenches or borrow pits shall be always taken for average dimensions.
• When the ground is fairly uniform “Deadman” or “Tell-Tales” shall be left at suitable intervals to determine the average depth of excavation.
• While for uneven or sloping ground, diagonal “Tell-Tales” shall be left.
• Note: 10% of the deduction shall be made in case of ordinary consolidated fills and in case of consolidation done by heavy machinery, a deduction of 5% shall be made. These deductions shall be adopted when it is not possible to make measurements from cutting and filling.

Cost Estimation

• Cost estimation may be defined as the process of forecasting the expenses that must be incurred to manufacture a product.
• These expenses take into consideration all expenditures involved in design and manufacture with all the related service facilities such as pattern making, tool making as well as a portion of the general administrative and selling costs.
• Cost estimates are the joint product of the engineer and the cost accountant.
• Estimating is the calculation of the costs which are expected to be incurred in manufacturing a component in advance before the component is actually manufactured.
• Costing may be defined as a system of accountants which systematically and accurately records every expenditure in order to determine the cost of a product after knowing the different expenses incurred in various departments.
  

Tendering 

• it is the process by which bids are invited from interested contractors to carry out specific packages of construction work.
•  It should adopt and observe the key values of fairness, clarity, simplicity and accountability, as well as reinforce the idea that the apportionment of risk to the party best placed to assess and manage it is fundamental to the success of a project.

Project scheduling

• it is a mechanism to communicate what tasks need to get done and which organizational resources will be allocated to complete those tasks in what timeframe. A project schedule is a document collecting all the work needed to deliver the project on time.

Project planning

• it refers to everything you do to set up your project for success. It’s the process you go through to establish the steps required to define your project objectives, clarify the scope of what needs to be done and develop the task list to do it.

Note: Scheduling is a part of project planning.

The various techniques used in project network analysis are:

• 1. Bar chart or Gantt chart
• 2. Linked bar chart
• 3. Mile stone chart
• 4. Work Breakdown structures
• 5. Critical Path Method (CPM)
• 6. PERT analysis - Program Evaluation and Review Techniques
• 7. Procedure Network analysis

Measurement Book (M.B.): 

• Measurement of all works and supplies are recorded in a special type of note book, called Measurement Book (MB). 
• It is used for making payments to the contractor. 
• The payment to the work done by contractor is made based on the Measurements of work done by contractor. 
• It basically consists of 3 main terms length, breadth and depth.

For example:

• Let a contractor has laid a slab for a building and he wants the payment.
• The length, breadth and depth of the slab will be recorded in MB and quantity will be calculated as some X cum. 
• The contractor will be paid according to the rate agreed in the agreement bond as so many Rs. per cum.

The construction manager can play the most vital lead role in achieving the project goals by performing the following functions effectively and efficiently:

• 1. Envisioning the task ahead
• 2. Enabling the individuals to perform the task systematically and efficiently.
• 3. Setting targets and monitoring performance.
• 4. Providing resources support.
• 5. Implementing a sound incentive scheme.
• 6. Communicating feedback.
• 7. Motivating the work force.
• 8. Building the line supervisors team.
• 9. Creating safe working environments.
• 10. Abiding by professional ethics.
• 11. Leadership 

Total float:

• The time span by which starting or finishing time of an activity can be delayed without delaying the completion of the project. It is the maximum available time in excess of the activity completion time.

Free float:

• The time span by which delay can be made without delaying the succeeding activities. It affects only preceding activity.

Independent float:

• It is the minimum excess available time which exists without affecting any of succeeding or preceding activities.

Interfering float:

• It is similar to head event slack.

Earnest money deposit

• It is the amount to be deposited by all the contractors when they submit their tender. EMD of the contractors whose tender is not accepted will be refunded
• Generally, 1%-2% of the estimated cost is submitted as the EMD.
• To ensure that a Bidder does not submit a Dummy Bid or back out at the time of tender opening, Government Department collects a small refundable fee from each bidder, which is called EMD. EMD is always in the form of a Demand Draft & cheques or cash are strictly not allowed.
• The success of a project largely depends on the capability of the contractor/vendor. Pre-qualification is a process to select competent contractors having technical and financial capability commensurate with the requirements of the particular procurement (Project / supply of goods/ hiring of services).
• So it is essential to call for the contractor’s credentials when a tender is invited.

Piece-work agreement

•  It is that for which only rate is agreed upon without reference to the total quantity of work to be done in a given period. In this type of agreement detailed specifications and the total cost of the whole work to be done are mentioned. It is terminable from either side at any time and cannot be called as a contract in true sense.
• It is suitable for urgent small work or if current contractor delays to execute the work or uses inferior quality of materials or leave the work partially complete, another contractor may be engaged at any time.

Item rate contract -

•  This contract is mostly followed by INDIAN Railway

Tender

It is a written offer submitted by the contractors in pursuance of the notification given, to execute certain work or supply of some specified articles or transport of materials at certain rates with the terms and conditions laid down in the tender documents.

Tender Form: 

• It is a printed standard form of contract giving standard conditions of a contract, general rules and directions for the guidance of contractors. There is also a memorandum for giving:
• i) General description of work, 
• ii) Estimated cost,
• iii) Earnest money, 
• iv) Security deposit,
• v) Time allowed for the work from date written order to commence and 
• vi) Columns for signature of contractor before submission of tender, signature of witness to contractor’s signature and signature of the officer by whom accepted.

• This is a part of tender document.

Item rate contract: 

• It is also known as unit-price contract or schedule contract. For such contracts, contractors are required to quote rates for individual items of work on the basis of schedule of quantities furnished by the department. This type of contract is followed by Central Public works and Railway departments.

Lump-Sum Contract:

•  In this form of contract, the contractors are required to quote a fixed sum for execution of a work complete in all respect i.e. according to the drawing, designs and specifications supplied to them with the tender within the specified time.
• The departmental schedule of rates for various items of work are also provided which regulates the payment to the contractor in respect of the items of works involved for any additions and alterations not covered by the original work.

Price Work Agreement:

•  It is type of contract in which the rate is agreed upon without reference to the total quantity of work to be done or the quantity of work to be done within a given period. But the detailed specifications and the total cost of the whole work to be done are mentioned.
• There is no security money and penalty clause and it is usually adopted for urgent small work and may be taken up for execution without inviting tender and a reasonable time is saved.

Target contract: 

• It is the type of contract where the contractor is paid on a cost-plus percentage basis for work performed under this contract, and in addition he receives a percentage plus or minus on savings or excess effected against either a prior agreed estimate of total cost or a target value arrived at by measuring the work on completion and valuing prior agreed rates.

Resources smoothing:

• It is the first approach of solving the resources allocation problem, in which the resources are considered to be unlimited. The original project duration (i.e. duration along the critical path) is however maintained.
• The start times of some of the activities are shifted within their available floats so that uniform demand is created for the resources.
• The smoothing or adjustment of resources resulting in least variation of resource demand is known as resource smoothing.

The statistical quality control

The statistical quality control evaluates the batch quality and controls the quality of process and products.

It uses following techniques

Sampling inspection:

•  A random sample is selected from a lot and inspection is done for that sample

Analysis of the data:

•  The results of sampling are analyzed by determining mean, range, standard deviation and the control limits.

Control charting:

•  Control limits are marked on a graph paper and the individual observations are marked on the graph, it takes the shape of control chart. If any observation is out of the limit it is clearly seen on the chart, and the corrective actions are taken to improve the product quality.

Which of the following are the sources of variation in quality control process in construction?

• 1. Material
• 2. Operator
• 3. Inspection activity

• Select the correct answer using the codes given below:
• Answer is 1 and 2.

Safety programs

Accident

• Accidents are an unplanned and unexpected occurrences that upsets the planned sequence of events and actions resulting in the loss of production injury to the person and damage to plants and equipment.
• Safety program generally does not talk anything about after-effects of accidents (compensation and medical payment). It always focuses on the prevention of accidents and how to develop a safe working procedure and environment.

Cost of an accident = Direct cost + Indirect cost

Direct costs

• These are the expenses incurred from and directly linked to an accident. Direct cost includes worker’s compensation payment, lost wages, medical expenses, and legal services.

Indirect cost

• It is real expenses associated with accidents. It may diffucult to assess these expenses for induvidual cases. 

Indirect cost includes:

• 1. Training replacement employees
• 2. Accident investigations
• 3. Implementation of corrective measure
• 4. Lost productivity
• 5. Injury reserve costs
• 6. Repairs of damaged equipment and property
• 7. Cost of absenteeism

Cost types

Operating cost 

• It incurred when the equipment is operated. The operating cost of equipment is influenced by various parameter namely no. of operating hours, location of job site, operating condition, category of equipment etc.

The operating cost consist of following.

• (a) Repair and maintenance cost
• (b) Fuel cost
• (c) Cost of lubricating oil
• (d) Tire cost
• (e) Equipment operator wages
• (f) Cost of replacing higher wear item.

Occupation safety and health (OSH):

• It is referred to as occupational health, workplace health and safety (WHS) is a multidisciplinary field concerned with the safety, health, and welfare of people at work. It applied on mining, factories, ports and construction.
• Occupational Safety and Health (OSH) is an area concerned with protecting the safety, health, and welfare of people engaged in co-workers, family members, employees, customers, and many others who might be affected by the workspace environment. 

Importance of safety:

• 1. Humanitarian reasons
• 2. Economic reasons
• 3. Organizational image
• 4. Laws and regulations

Important aspects of safety programmes:

• 1. Using a qualified safety person.
• 2. Develop safe working conditions.
• 3. Promote participation of workers for safety.
• 2. Assigning a competent person.
• 3. Making regular job site safety inspections.
• 4. Following safety procedures and rules.
• 5. Following safety procedures and rules.
• 6. Providing on-going safety training.
• 7. Enforcing safety rules and using appropriate discipline.

Quality and Quality Control

There are three types of quality:

i) Quality of Design: 

• Based on the market survey, the concept of the product is developed and then the specifications are finalized. It involves the sharing of ideas between marketing, manufacturing, and R&D units.

ii) Quality of Conformance:

•  It means the extent to which a company can develop products based on the customer requirements as per the specifications defined in the quality of design.

iii) Quality of Performance:

•  It includes the after-sale service and logistical support from the organization.

Quality of conformance in construction is affected by the following:

• 1. Construction methods adopted, skill of workers, quality of the materials used.
• 2. Supervision to conform to the plans and specifications and control to act immediately if anything goes out of the way to avoid any wastages.
• 3. Inspection through NDT and other sampling methods to assess the quality and plan control measures.

Inspection process is carried out after completing all the machining, without removing the job from the work holding fixtures.
we can say that inspection process should be carried out after completing the job

Key reasons for encouraging startup entrepreneurship:

• Innovations
• New jobs and economic growth
• Bringing new competitive dynamics into the economic system
• Promoting the research-innovation system
• Bringing the values of pro-activity into the society

Some Schemes related to Entrepreneurs are

Atal Incubation Centre (AIC)

• Started by Niti Aayog in 2016
• It is an innovative funding scheme to promote entrepreneurs by covering their capital operational costs.

NewGen IEDC

• Department of Science & Technology (DST) introduced the New Generation Innovation and Entrepreneurship Development Centre (NewGen IEDC) Programme in 2017.
• It promotes “knowledge-based and technology-driven start-ups” through mentor-ship, guidance and support. 

FAR - Floor Area Ratio

The quotient obtained by dividing the combined covered area (plinth area) of all floors, excepting areas specifically exempted under these regulations, by the total area of the plot.

FAR - Floor Area Ratio

The aspects that govern in specifying FAR, some of them being:

• 1. Occupancy class
• 2. Types of construction
• 3. Width of street fronting the building and the traffic load
• 4. Locality where the building is proposed and the density
• 5. Parking facilities
• 6. Local fire fighting facilities
• 7. Water supply and drainage facilities

Floor Area Ratio = Total covered Area/Plot Area

Particulars of items	Units of measurements
Well sinking, pile driving, Dag-belling, Grouting of cracks or joints, Supply of pipes, Skirting, cornice	Meters
Plastering, pointing, Dado, White Washing, distempering, painting, polishing, coal tarring, removing of paint	Square meters
Tile roof, slate roofing, timber roofing, Ceiling, centring and shuttering, Damp proof course, Turfing or lining of canal, surface dressing or levelling, jail work or Jafri work, Wood work in doors and shutters, sawing of timber, wood work in partition and ply wood.	Square meters
Boring holes in iron, painting letters and figures, ornamental pillar caps, cleaning flues, cotton cords in sky light, Easing doors and windows, Fixing doors and windows	Numbers
Earthwork in excavation, puddling, Quarrying of stones, concreting, brickwork in foundation, stone masonry	Cubic meters
Rolled steel joists, steel reinforcement bars, binding of steel reinforcement, fabrication and hoisting of steel work	Quintals

The expected outturn for different types of work per workman per day are:

:

S.No	Particulars of items	Expected out turn (per mason per day
1.	Earthwork in the excavation in ordinary soil	3.00 cu m
2.	Brickwork in lime or cement mortar in foundation and plinth	1.25 cu m
3.	Random rubble stone masonry in lime or cement mortar	1.00 cu m
4.	Earthwork in the excavation in hard soil	2.00 cu m

The rate of particular item of work depends on the following:

• 1. Specifications of works and material about their quality, proportion and construction methods.
• 2. Quantity of materials and their costs.
• 3. Cost of labours and their wages.
• 4. Location of work
• 5. Conveyance charges.
• 6. Overhead charges
• 7. Profits of contractor, consultant and other parties involved.

Revised Estimte 

• The revised estimate is a detailed estimate for revised quantities and the rate of items of works originally provided in the estimate without material deviation of a structural nature from the design originally approved for a project.

It is required to be prepared for the following reasons:

• i) When a sanctioned estimate is likely to exceed by more than 5% either from the rates being found insufficient or from cause whatsoever except important structural alteration.
• ii) When the expenditure of works exceeds or is likely to exceed by more than 10% of the administrative approval (for work more than ₹5 lakhs/-)
• iii) When there are material deviations from the original proposal but not due to the material deviation of structural nature.
• iv) When it is found that the sanctioned estimate is more than the actual requirement.

Capitalized value of property

• The capitalized value of a property is the amount of money whose annual interest at the highest prevailing rate of interest will be equal to the net income from the property. To determine the capitalized value of a property, it is required to know the net income from the property and the highest prevailing rate of interest.

Detailed estimate:

• A detailed estimate should have documents such as report, specifications, drawings/plans, design charts and schedule of rates.

• Factors such as, material quantity, transportation of materials, location of site, labour charges, cost of equipment (commonly allowed: - 2% of the estimated cost), overhead charges (commonly allowed: - 2% of the estimated cost), contingencies & unforeseen (commonly allowed:- 4% of the estimated cost) items are needed to consider well while preparing the detailed estimate.

Plinth Area Estimate:

• Plinth area estimate can be achieved by multiplying the values of plinth length, plinth width & plinth area rate. Here the plinth area is referred as, external plinth area of the building at floor level.

• Simply it can be also stated as the roof covered area of a building. Plinth area rate is derived by dividing the total cost of a previously constructed building by plinth area of the previously constructed building.

Cube rate estimate:

• This type of estimate done by multiplying the volume of the building by the unit cubic rate achieved from the previously (also recent) estimate.

•  This type of estimate is a little bit more accurate than above mentioned methods and mostly suitable for multi storied buildings.

Preliminary estimate:

• It is also called budget, approximate estimate. This type of estimate is prepared in the initial stage of a project.
• To give a clear idea to the owner (client) about the amount of cost needed for the project and to get the approval from necessary sanctioning bodies.

Scrap Value: 

• Scrap Value is the sell value of dismantled materials of an asset at the end of it’s useful life. Scrap Value is counted in the calculation of depreciation of a property, generally @10% of the cost of the Structure.

Salvage value: 

• Salvage Value is the Estimated Value of an asset without dismantling it at the end of it’s useful life.

Book Value: 

• Book value is the amount shown in the account book after allowing necessary depreciations. The book value of a property at a particular year is the original cost minus the amount of depreciation allowed per year and will be gradually reduced year to year and at the end of the utility period of the property, the book value will be only scrap value.

Market Value: 

• The market value of a property is the amount which can be obtained at any particular time from the open market if the property is put for sale. The market value will differ from time to time according to demand and supply.

Rateable value: 

• It is the net annual letting value of a property, which is obtained after deducting the amount of yearly repairs from the gross income.

Annuity: 

• It is the annual periodic payments for repayments of the capital amount invested by a party.

Capitalised value: 

• It is the amount of a money whose annual interest at the highest prevailing rate of interest will be equal to the net income from the property.

Estimation of wet volume of concrete

• The yield of concrete per bag means we have to find a wet volume of concrete
• For M20, 1 : 1.5 : 3
• In the above ratios, 1 represents cement, 1.5 represents sand, 3 represents aggregate.
• ∴ Sum of ratio = 1 + 1.5 + 3 = 5.5
• Volume of cement =1 / sumofratio × volume of concrete
• The volume of one bag of cement = 35 litres = 35 × 10power3 m3
• The volume of wet concrete = (2/3) × volume of dry concrete

 

 The long wall and short wall method

• In long wall and short wall method, the wall along the length of the room is considered to be long wall and the wall perpendicular to the length of the room is considered to be short wall.
• To get the measurement of materials and work, length of long wall or short wall, centre line lengths of individual walls is calculated first. Then the length of long wall, (out to out) may be calculated after adding half breadth at each end to its centre line length.
• Thus the length of short wall measured into in and may be found by deducting half breadth from its centre line length at each end. These lengths are multiplied by breadth and depth to get quantities.
• The length of long wall usually decreases from earth work to brick work in super structure while the short wall increases.

Administrative approval:

For any project by the department, an approval or sanction of the competent authority with respect to the cost and work is necessary at the first instance. Thus administrative approval denotes the formal acceptance of the proposals for incurring expenditure by the concerned administrative department.

Technical sanction:

It means the sanction and order by the competent authority of the department to the detailed estimate design calculations, quantities of work rates and cost of work. After the technical sanction of the estimate is received the work is then taken up for construction.

Expenditure sanction:

It means the concurrence of the Government to the expenditure proposed in cases where this is necessary. In all other cases the act of appropriation or re-appropriation will operate as sanction to the expenditure concerned.

• Generally, 0.6 m is taken as the distance from the external walls and 0.8 m is the gap between piles.

Area of one cement bag = 0.3 m2

Height of one cement bag = 0.15 m

No. of bags = Space for cement/Volume of one cement bag

Different methods to calculate depreciation are as follows :

• a) Straight-line method
• b) Constant percentage method
• c) Sinking fund method
• d) Quantity survey method

Quantity survey method: 

• In this method, the property is studied in details and extent of physical deterioration worked out in endeavor to calculate the depreciation.

Sinking fund method: 

• In this metho, the depreciation is assumed to be annual sinking fund plus interest of the accumulated sinking fund till that year.

Constant percentage method: 

• In this method, the property is assumed to lose value annually at a constant percentage of its value.

Straight-line method: 

• In this method, the property is assumed to lose value by a constant amount every year.

Plinth area is also called as built-up area and is the entire area occupied by the building including internal and external walls. It does not include courtyard area.

Plinth area = Builtup area - Courtyard area

The approximate cost of the complete labor as a percentage of the total cost of the building is 25 % or 0.25.

The percentage breakup of total cost of building is as follows:

:

Type	Material cost (in % of total cost)	Labour cost (in % of total cost)
Residential Building	60 – 70	25 – 35
Industrial Building	65 – 75	20 – 30

The total cost of building also involves cost of casualty, material hike, environmental conditions, delays, insurance etc. which constitutes 5 - 10 % of the total cost.

Approximate construction cost estimates

• Plinth area method, 
• Cubical contents method and 
• Unit base method are approximate construction cost estimates:

Plinth area method:

• Cost of Construction = Plinth Area * Plinth area rate
• Here, area is measured using outer dimensions of the buildings.

Cubical Contents Method:

• 1. Relevant for multi-storeyed buildings.
• 2. Cost of Construction = Volume of Buildings * Local Cube Rate
• 3. It is more accurate than plinth area or unit base method.

Unit Base Method:

• 1. Cost of Construction = Total no of units * unit rate of each item
• 2. For schools and colleges, the unit is ‘one student’ and for hospital, th e unit is ‘one bed’.

For 1 m3 volume of brick work, the bricks required are 500.

Mortar needed = 1 – 500 × 0.19 × 0.09 × 0.09 = 0.23 m3

Add 15% extra for frog filling and wastage

Volume of wet mortar = 0.23 × 1.15 = 0.265 m3

1 m3 of wet mortar = 1.25 m3 of dry mortar

 0.265 m3 of wet mortar = 0.33 m3 of dry mortar

Dry mortar as a percentage of brick work = 33%

Materials for different item work:

:

1	Bricks used for brickwork (20 cm × 21 cm × 10 cm)	500 Nos. for 1 cu.m
2	Dry mortar for brickwork	33% of the volume of brickwork
3	Dry mortar for rubble stone masonry	42% of the volume of stone masonry
4	Volume of dry concrete	1.54 times the volume of wet concrete
5	Volume of dry mortar	1.25 times the volume of wet mortar
6	Dry mortar for 12 mm plastering	2 cu.m for 100 sq.m

• The yield of concrete per bag means we have to find a wet volume of concrete
• For M20, 1 : 1.5 : 3
  • In the above ratios, 1 represents cement, 1.5 represents sand, 3 represents aggregate.
• ∴ Sum of ratio = 1 + 1.5 + 3 = 5.5
• Volume of cement  volume of concrete
• The volume of one bag of cement = 35 litres = 35 × 10-3 m3
• The volume of wet concrete = (2/3) × volume of dry concrete

Lease and Lease Holder

• The leaseholder is known as the lessee and holds the physical possession of the property for a definite period under terms and condition specified in the lease document.

Other forms of the lease are as follows:

Building Lease: 

• In this type of lease, the owner of a freehold open plot of land let out his land to the lessee on an agreed amount of premium or ground rent or a combination of both.

• The leaseholder may then erect a building over there up to a specified amount and within a specified time and he maintains the property and can reside or earn income through such property.

Occupational Lease: 

• In this type, the lease is granted against premium or rent or a combination of the two by an owner of property consisting of land and building or other structures for occupancy for a fixed period to another person.

Sublease – 

• A leaseholder may render sub-lease of his leasehold property to other persons subject to the terms and conditions in the original lease and be allowed by Local regulations or Court of Law.

Perpetual Lease – 

• When the lease of a property is given for a number of years providing a condition that lease is renewable time to time, even for endless time according to the desire of the leaseholder.

Long Term Lease

When a lease is granted for a period of 99 years, it is known as long term lease and when it is for 999 years it is said to be perpetuity or for an endless duration.

Short Term Lease

• A short-term lease generally refers to a lease with a duration of fewer than six months. Often, they are based on a month-to-month rental agreement, which may or may not is renewed at the end of each month.

 the annual sinking fund

Annual sinking fund (I) is given by:

I=Si(1+i)n−1

Where,

S = total amount of sinking fund to be accumulated

i = rate of interest

n = number of years required to accumulate the sinking fund

Materials for different item work:

1 Bricks used for brickwork (20 cm × 21 cm × 10 cm)500 Nos. for

• 1 cu.m

2 Dry mortar for brickwork

• 33% of the volume of brickwork

3 Dry mortar for rubble stone masonry

• 42% of the volume of stone masonry

4 Volume of dry concrete

• 1.54 times the volume of wet concrete

5 Volume of dry mortar

• 1.25 times the volume of wet mortar

6 Dry mortar for 12 mm plastering

• 2 cu.m for 100 sq.m

Different method for approximate estimation

of construction projects are as follows:

Plinth area method: 

• The cost of construction is determined by the multiplying plinth area with the plinth area rate. The area is obtained by multiplying length and breadth (outer dimensions of the building).

• ∴ The estimate prepared on the basis of the built-up covered area at the floor level of any storey of a building is known as plinth area estimate.

Cubical Contents Method: 

• This method is generally used for multi-storeyed buildings. It is more accurate than the plinth area method and unit base method.
• The cost of a structure is calculated approximately as the total cubical contents (Volume of buildings) multiplied by Local Cubic Rate.

Unit Base Method: 

• According to this method the cost of the structure is determined by multiplying the total number of units with a unit rate of each item. In case schools and colleges, the unit considered to be as 'one student' and in case of a hospital, the unit is 'one bed', the unit rate is calculated by dividing the actual expenditure incurred or cost of a similar building in the nearby locality by the number of units.

Lintel

A lintel is a beam placed across the openings like doors, windows etc. in buildings to support the load from the structure above. The width of lintel beam is equal to the width of wall, and the ends of it is built into the wall.

The bearing provided should be the minimum of following 3 cases.

• • 10 cm
• • Height of beam
• • 1/10th to 1/12th of span of the lintel

The lintel based on material may be classified as following:

Timber Linter, Steel Lintel, Stone Lintel, Brick Lintel, Reinforced Lintel, etc.

Center line method

• In this method of estimation, the total centerline length of walls in a building is first calculated, then the center line length is multiplied with the breadth and depth of the respective items to get the total quantity at a time.

Deductions

• L Junction - There is no need to deduct from total centreline length.
• T Junction - Half (1/2) breadth wall measurement should be deducted for a T junction.

Valuation

• The technique of finding the fair price of an existing building or property is known as valuation.
• Valuation of property is done to work out the amount of fair rent of a building, buying or selling of the property, etc., especially when it is requisitioned by the government or semi-government organization.
• Future value of the property cannot be determined by valuation.

There are generally six methods of valuation:

• Rental Method of Valuation
• Direct Comparisons of the capital value
• Valuation based on the profit
• Valuation based on the cost
• Development method of Valuation
• Depreciation method of Valuation

Valuation of a property may be prepared by different methods as follows:

• a) Rental method of valuation ⇒ Suitable for a property with the new building

• b) Land and building method of valuation ⇒ Suitable for special purpose properties such as schools, police stations, etc

• c) Capital value method ⇒ Suitable for open land, clubs, out homes, etc
• d) Profit-based valuation ⇒ Suitable for shops, hotels, cinemas, etc
• e) Development method of valuation ⇒ Suitable for an underdeveloped property
• f) Amortisation method ⇒ it is based on dynamic allocation table.

 

Floor live load and Roof live load

• The nature of roof live load is different from that of floor live load so the approach to reducing roof live load is different from that used for floor live load.
• The requirement is presented in ASCE 7-05 4.9. 
• The commentary in ASCE 7-05 C4 about roof live load reductions explains the anticipated difference in the use of roof areas vs. floor areas.
• The reduction formula has two reduction terms: One for the tributary area supported by the structural element (R1) and the other for the slope of the roof surface (R2).
• R1 is formulated in such a way that there is no reduction for tributary areas less than 200 sqft and is maximum when the tributary area reaches 600 sqft, varying linearly in between.
• Formula can be written as: R1 = max[min(1.2 - 0.001 × At, 1), 0.6]
• R2 is formulated in such a way that there is no reduction for the roof with slopes that have a slope ratio of 4:12 or less. It is maximum for slope ratios of 12:12 or greater.
• Formula can be written as: R2 = max[min(1.2-0.05F, 1), 0.6]
• Where "F" is the rise in the slope ratio F:12.
• This slope reduction method for roofs assumes a normal roof that is not expected to have any significant occupancy. If the roof has such an occupancy, then the area reduction for roof live loads may not be taken.

FAR - Floor Area Ratio

The aspects that govern in specifying FAR, some of them being:

• 1. Occupancy class
• 2. Types of construction
• 3. Width of street fronting the building and the traffic load
• 4. Locality where the building is proposed and the density
• 5. Parking facilities
• 6. Local fire fighting facilities
• 7. Water supply and drainage facilities

∴ Floor Area Ratio = Total covered Area/Plot Area

Note:

• Grouting refers to the injection of pump able materials into a soil to change its physical characteristics.
• It is generally a mixture of water, cement and sand.

• Grouting of cracks, joints, etc. is measured in meter whereas bituminous grouting of road metal cement grouting of concrete is done in a square meter.

• Bituminous road surfacing is done in square meter.

• Pitching of brick is done in cubic meter.

Deductions 

related to plastering are as follows:

• For small opening up to 0.5 m2 area, no deduction in plastering is made.
• For opening of size 0.5 m2 to 3 m2 area, deduction is made on one face of the wall.
• For openings of size above 3 m2, deduction is made on both faces of the wall, but the area of sill, jamb and soffits of the opening is added.

There are many other clauses in IS Code such as:

• 1. If both sides of wall are plastered with a different mix
• 2. If only one side of the wall is plastered and other side is not

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