CVL245

Construction Management
Sahil Bansal, Ph.D.
Assistant Professor
Department of Civil Engineering
Indian Institute of Technology Delhi
sahil@iitd.ac.in
http://web.iitd.ac.in/~sahil
 General
✓ Credit: 2 (L:2 - T:0 - P:0)

✓ Schedule: 11:00 AM (Mon & Wed)

✓ Venue: LH-408

Dr. Sahil Bansal, IITD 2

 Course Content
The course revolves around the various activities encountered during the life cycle of a civil engineering
project.
1. Introduction to construction projects, phases in a project, stakeholders
2. Project cost estimation, rate analysis and specifications
3. Project selection using time value of money concept
Minor I
4. Tendering process and construction contract
5. Project planning and network analysis-PERT, CPM and Precedence Network
Minor II
6. Resource scheduling
7. Time cost trade off
8. Time cost monitoring and control using S-curve and earned value analysis
9. Construction claims and disputes
10. Introduction to construction quality
11. Introduction to construction safety
Most of the topics are introductory in nature.
Dr. Sahil Bansal, IITD 3
 Grading policy
• Minor-I (30%)
• Minor-II (30%)
• Major (40%)
• Attendance Policy: A minimum of 75% attendance is required for appearing Major
Examination.
• Timble system will used for attendance.

Dr. Sahil Bansal, IITD 4

Part 1:
▪ Introduction to construction projects
▪ Phases in a construction project
▪ Stakeholders in a construction project
 Construction Projects
• Construction, in one form or the other, has been practiced since the dawn of civilization.
• There are many types of construction projects, each one of which fulfils a particular objective.
Residential
Building
Commercial
Projects
Institutional

Transportation system
Heavy Hydraulic structure
Civil Engineering
Projects Engineering Water system
Project Power distribution
…..

Power plants
Refineries & chemical plants
Industrial
Steel plants
Projects
Manufacturing plant
…
Dr. Sahil Bansal, IITD 6
 Every construction project is unique in terms of ….
• One time activity
• Complexity
• Cost, method and time for execution
• Quality Standards
• Local conditions
• People involved in the construction process
• Design of the facility
• Involves commitment of huge amount of resources in terms of funds, manpower, materials, equipment and
time.

Dr. Sahil Bansal, IITD 7

 Phases in a construction project
• Initiation phase

Idea
Pre-project • Project concept
phase phase
• Feasibility phase

• Design phase
Project • Tendering phase
• Execution phase
phase • Commissioning

• Utilization phase
Post- • Decommissioning
project (Close-down
Reality

phase)
phase
Dr. Sahil Bansal, IITD 8
 Phases in a construction project
Conceptual and
Feasibility Studies

Engineering
Design

Contracting and
Procurement

Construction

Commissioning

Utilization and
Decommissioning

Dr. Sahil Bansal, IITD 9

 1. Conceptual and Feasibility Studies
In this stage, ideas generated by individuals / a group of people are studied. Following important points are
carried out to establish the viability of the project.
• Conceptual development
• Technical and economic feasibility studies
• Land and geological survey-location of the project
• Environmental impact assessment
• Social impact assessment
• Enumeration of major problems in translating the project to reality
Outcome of this stage: A report dealing with investigation and studies concerning the problems to be
encountered and its solution.

Dr. Sahil Bansal, IITD 10

 Example
Suppose a state highway is crossing the railway line situated in a small district level town. The idea is to
construct a fly over. In this phase, the following points are examined-
• Is it necessary to have a fly over now? This point is studied with regard to the level of traffic on the road
as well as on the railway line. If the traffic load is low, the project may be discarded based on cost-benefit
analysis.
• The cost of construction is roughly estimated and source of money is discussed.
• Based upon the level of traffic, the basic model of the fly over is prepared, with respect to width, length of
the approach road, etc.
• How to acquire land for widening of road.
• Preliminary soil investigation
• Environment/social impact assessment is not very important for this project.

Find out a project that has been or was delayed due to the object of environmental impact.
Find out a project that has been or was delayed due to the object of social impact.

Dr. Sahil Bansal, IITD 11

 2. Engineering Design
In this stage, project takes the definite shape. All the technical issues related to the project are carried out.
Design phase of project is carried out in two phases:
• Preliminary design This stage involves primarily the studies of various design alternative, their economic
comparative studies and architectural aspect. Also, in this stage, detailed field investigation such as soil
testing, geological, hydrological data collection, market survey, etc are carried out. (These steps are also a
part of feasibility study.)
• Detailed Design- In this stage, the project is broken down into its components and each of the elements
are analysed and designated, such that the engineer renders the explicit drawings and specifications which
is used for construction.
Outcome of this design phase: The following are the outcome of this phase -
• Drawing of the structures/facilities to be constructed
• Specifications of component to be employed which contain detailed description of the amenities to be
constructed.
Dr. Sahil Bansal, IITD 12
 Example
In the example of a flyover, this steps may involve:
Preliminary design
• Carrying out detailed soil investigation and site investigation to get the idea of method of construction.
• Selection of the bridge deck type, i.e. whether a steel or concrete, box grider bridge or prestress.
• Fixing exact dimension of the flyover, i.e. number of piers, width of foot path, architectural aspect, etc.
Detailed Design-
• Preparing Drawings: The detailed drawings of plan, elevation and section, drawn to a scale are necessary to
take the details of measurements of various items of work.
• Defining Specifications: The specifications gives the nature, quality and class of materials, their proportion,
method of execution and workmanship and the class of labour required. The cost of the work varies with its
specifications. The cement mortar with 1:3 is more costlier than cement mortar with 1:6.

Dr. Sahil Bansal, IITD 13

 3. Contracting and Procurement
In this stage, the bill of quantities are prepared, final cost estimate is worked out. Most of the agreements are
signed and relationships between different parties involved is defined following points are generally
addressed during this time. The project has to be executed according to the drawing and specification.
• Tender notices are advertised
• Qualification of contractor / suppliers is studied
• Contract is awarded to execute the work
• For many of the projects, such as industrial projects, industrial material and equipment to be installed is
purchased
Outcome of this stage: Contract document, which is a legal document describing the terms and conditions to
execute the project.

Dr. Sahil Bansal, IITD 14

 Example
In the example of a flyover, this steps may involve:
• Preparing bill of quantities: The BOQ is a document showing a list of everything needed to build something
and how much each item will cost
• Estimating the final cost (by the client/owner)
• Inviting bids
• Submission of bid by various contractors (contractors will prepare their own estimate of the final cost)
• Analysis and evaluation of bids by contractors
• Agreement/signing contract between the client and qualified contractor

A contractor in general is responsible for providing all the material, labor, equipment and services necessary for the
construction of the project. A contractor often hires specialized subcontractors to perform all or portions of the
construction work. When using subcontractors, the contractor is responsible for the quality of all work performed by
any and all the hires.

Dr. Sahil Bansal, IITD 15

 4. Construction
This is the most important phase of a civil engineering project, where the major portion of the money is invested. A lot of
issues of project management are involved during this phase. The main work involved during this phase are:
• How to do the particular construction (Construction Methods)
• How to manage materials for constructions (Material Management)
• How to organize labour & equipment (Labour and equipment Management)
• How to breakdown the overall work into activities (Construction Planning)
• How to calculate the time and resources required to complete the activity (Construction Scheduling)
• How to manage the money invested (Construction Finance)
• How to organize the different personals or companies involved (Constructional Organization management)
• How to conform the construction is according to specifications (Quality of conformance)
• How to check whether the project is according to construction schedule and quality (Construction supervision)
• How to implement the safety measure during construction (Construction safety)
• What to do if things are not moving according to plan (Disputes any arbitration, Labour laws, Penalty)
• How to avoid redundancy in the system (Value engineering)
Outcome of this stage : Facility or structures

Dr. Sahil Bansal, IITD 16

 5. Commissioning of a project
Aim of this phase is to check that the project has been carried out according to the contract document.
Following activities are carried out during this stage:
• Check if each component is functioning according to design and specification
• Check if the entire system is functioning accordingly as desired
• To remove the defect if any during construction work
• Perform safety audit
• Preparation of operational and maintenance manuals

Dr. Sahil Bansal, IITD Picture source: www.axiomlandbase.in 17

 6. Utilization and Decommissioning
Utilization
• Basic infrastructure facilities created should be utilized to its fullest capacity
• Regular maintenance
• Regular repair of the part getting damaged

Decommissioning
One the project has lived its intended life, it is dismantled and disposed of.

Dr. Sahil Bansal, IITD 18

 Phases in a construction project
Conceptual and Bar Chart • Depending upon the
Feasibility Studies contractual relations
and way of project
management, phases
Engineering can overlap to the
Design various degrees.
• Each phase require
Contracting and different skills and
Procurement hence should be
carried out by
different people.
Construction
• Pre-project phase
requires creativity,
while a project phase
Commissioning require rigour.
• Relatively, a large
number of people are
Utilization and involved in project
Decommissioning … phase.
Dr. Sahil Bansal, IITD 19
 Stakeholders of a Construction Project
Project stakeholders are individuals/organisations who are actively involved in the project, or whose
interests may be positively/negatively affected by the project

Client Consultants
Investors Users
(Owner) (Designer)

Architect Contractor Regulators

* This list is not exhaustive

The challenge of project manager
and there are other people
is to have coordination among the
who could be also
stake holders. stakeholders in a project.
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 Challenges of Construction
• There are three components of project
• Cost of the project (Budget)
• Time of completion of the project (Schedule)
• Quality of construction facilities (Scope)
• The job of a project manage is to establish the balance between the aforementioned three components of
the project (construction management is one of the most difficult disciplines).

Time

Quality Cost

Dr. Sahil Bansal, IITD 21

 Importance of construction and construction industry
• Developing country —> Labour intensive style of construction —> Provides employment on large scale
(engineers, managers, skilled workers, unskilled workers / male & female / urban & rural)
• Forward movement of construction industry is an indicator of growth of the country.
• If construction project schedules are not maintained, the cost increases by leaps and bounds.
• Use of machine and equipment in construction industry increases the quality of construction.
• The art of construction has slowly developed as a science through ages. In our country, building
construction in rural and semi-urban areas is more or less an art.

Dr. Sahil Bansal, IITD 22

Part 2:
▪ Cost estimation
▪ Specifications
▪ Rate analysis
 Estimate
• During construction project planning and implementation, one needs to know the quantities and costs of
various items required to meet the objective of the project.
• The purpose of cost estimating is to forecast the cost of a project prior to its actual construction.
• Estimate gives an idea of the cost of the work and hence its feasibility can be determined i.e. whether
the project could be taken up with in the funds available or not.
• Estimate is required to invite the tenders and quotations and to arrange contract.
• Estimate is also required to control the expenditure during the execution of work.
• Estimate gives an idea of time required for the completion of the work.
• During the life cycle of a project, different parties for various reasons require an estimate. The details and
method of estimations depend upon the needs and level of management decisions.

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 Estimating Cost
• Estimating is not an exact science. Knowledge of construction, common sense and judgment are required.

• Estimating material costs can be accomplished with a relatively high degree of accuracy. The quantity of
materials for a particular job can be accurately calculated from the dimensions on the drawings for that
particular job. After the quantity of material is calculated and knowing the unit prices, the cost could be
estimated by multiplying the quantity by the unit prices.

• Accurate estimating of labour and equipment costs is considerably more difficult to accomplish. The cost of
labour and material depends on productivity rates, which can vary substantially from one job to another.
The skill of the labour, job conditions and many other factors affect the productivity of labour.

• At the beginning of a project, the estimate cannot be expected to carry a high degree of accuracy since little
information is known. As the design progresses more information is known and accuracy should improve.

Dr. Sahil Bansal, IITD 25

 Data required to prepare an estimate
• Drawings : The detailed drawings of plan, elevation and section, drawn to a scale are necessary to take the
details of measurements of various items of work.

• Specifications : The specifications gives the nature, quality and class of materials, their proportion, method
of execution and workmanship and the class of labour required. The cost of the work varies with its
specifications. The cement mortar with 1:3 is more costlier than cement mortar with 1:6.

• Rates : The rates for various items of work, the rates of various materials to be used in construction, the
wages of different categories of labour should be available for preparing an estimate. The location of the
work and its distance of source of materials and cost of transport should be known. These rates may be
obtained from the Standard Schedule of Rates prepared by the engineering departments.

List of rates of various items

Dr. Sahil Bansal, IITD 26

 Estimation Methods
• Approximate methods : estimate is made with limited information on project scope, and is usually made
without detailed design and engineering data.

• Functional unit estimate

• Plinth area estimate

• Cube rate estimate

• Approximate quantity method estimate

• Detailed estimate: Detailed estimates are prepared once the design has been completed and all construction
documents prepared. The estimator divides the project into individual elements of work and estimates the
quantities of work for each element. Next, the individual elements of work are priced to determine an
estimated cost for each one.

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 Functional Unit Estimate
• This method involves the use of a single functional unit that serves as a multiplier.

Function Unit
Hospital Per bed
House Per sq-meter
Hotel Per room
Factory Per bay
Garage Per car
Store Per ton/m3 storage
School Per student/per class room

Total Estimated Cost of Building Project = Number of Units × Cost per Unit

Dr. Sahil Bansal, IITD 28

 Example - Functional Unit Estimate
• This method is the simplest and quickest method of estimating the cost of a proposed construction project. In this
method, the quantity surveyor counts the number of units which are going to be accommodated in a building, for
example the number of beds in a hospital or number of class rooms in a school. The number is then multiplied by the
cost per unit to get the total estimated cost of the project.
• Before using this method the estimator has to collect information from previous similar contracts which were
completed in the same area or in neighbouring areas.

• Example:-
Let us assume that a 150 bed hospital has to be constructed and the client has requested to calculate the approximate
cost of this project. The quantity surveyor finds there is a 200 bed hospital situated nearby which has been constructed
two years ago and the sum of money that had been spent was Rs. 2,00,00,000.
Cost per bed of the previously constructed Project = 2,000,000 / 200
= 1,00,000
Total Estimated Cost of the Project = 150 x 1,00,000 = 1,50,00,000

Dr. Sahil Bansal, IITD 29

 Functional Unit Estimate
Advantages
• It can be done quickly where a ballpark figure is required instantly
• The estimate can be done even if there are no drawings or specifications
• No take-off or measurements needed
• Useful for buildings where standard-sized units occupy most of the space
• Little information is required from client (i.e. number of units)
Disadvantages
• It’s not a reliable method
• Large deviation from the accurate value
Material take off (MTO) is a term
• It is not based on drawings or specifications used in engineering and construction
• Cost escalation not taken in to account and refers to a list of materials with
quantities and types (such as specific
grades of steel) that are required to
build a designed structure or item.

Dr. Sahil Bansal, IITD 30

 Plinth Area
Def:
• Plinth area: Plinth area is the covered built-up area measured at the floor level of any storey or at the floor level of the
basement. Plinth area is also called as built-up area and is the entire area occupied by the building including internal
and external walls. (also called built up area)
• Carpet area: Carpet Area is the area enclosed within the walls, actual area to lay the carpet. This area does not include
the thickness of the inner walls.
• Plinth area is generally 10-20% more than carpet area.

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 Plinth Area Estimate
• Plinth area estimates are made by determining the plinth area of a building and multiplying it by the plinth area rate.
• Plinth area rate (PAR) is deduced from the cost of a similar building having similar specifications, height and type of
construction in the same locality.

Total Estimated Cost of Building Project = Plinth area × PAR

Dr. Sahil Bansal, IITD 32

 Example - Plinth Area Estimate
Prepare an approximate estimate of building project with total plinth area of all building is 800 sqm. and from following
data.
i. Plinth area rate Rs. 4500 per sqm
• Items other than civil
ii. Cost of water supply @7½% of building cost engineering such items
iii. Cost of Sanitary and Electrical installations each @ 7½% of building cost are called lump sum
iv. Cost of architectural features @1% of building cost items.
• In general, certain
v. Cost of roads and lawns @5% of building cost
percentage on the cost
vi. Cost of P.S. and contingencies @4% of building cost of estimation is
Determine the total cost of building project. allotted for the above
lump sum items.

Dr. Sahil Bansal, IITD 33

 Cube Rate Estimate
• The cube rate estimates are made by determining the overall volume of the enclosed space of a building
and multiplying it by the cube rate.
• Cube rate is deduced from the cost of a similar building having similar specifications and type of
construction in the same locality

Total Estimated Cost of Building Project = Overall volume ×

cube rate

Dr. Sahil Bansal, IITD 34

 Example - Cube Rate Estimate
Prepare the rough estimate for a proposed commercial complex for a municipal corporation for the following data.
i. Plinth Area = 500 m2 /floor
ii. Height of each storey = 3.5 m
iii. No. of storey’s = G+2
iv. Cubical content rate = Rs. 1000/m3
v. Provided for a following as a percentage of structured cost
a. water supply & Sanitary arrangement -8%
b. Electrification -6%
c. Fluctuation of rates - 5%
d. Contractors profit - 10%
e. Petty supervision & contingencies - 3%

Dr. Sahil Bansal, IITD 35

 Approximate Quantity Method Estimate
• This method is based on the total length of the wall in a building, which is found from the drawings and
then using per meter rate the total cost is estimated.
• For this method the building is considered to be divided into two parts:
• The foundation including the plinth
• Excavation
• Brickwork
• Damp-proof course
• Super structure
• Brickwork
• Woodwork
• Flooring
• Roof
• Finishing …

Dr. Sahil Bansal, IITD 36

 Detailed Estimate
Estimating involves the following operations:
a. Different items of work involved
b. Quantities of different items of work
c. Unit rate of different items of work

Unit measures Area

E.g. no of doors windows Area of flooring/paint
Linear Volume
Length of pipe Concreting/brickwork/excavation

Dr. Sahil Bansal, IITD 37

 Quantity take-offs
• Quantity take-offs (QTO) are a detailed measurement of materials and labor needed to complete a construction
project.
• The quantities like earth work, foundation concrete, brickwork in plinth and super structure etc., can be workout
by any of following two methods:
A. Long wall - short wall method
B. Centre line method
Calculate the volume of excavation for the trench shown
500 500

500 Section AA
GL
800
A A 2000 500

500

5000 All units are in mm

Dr. Sahil Bansal, IITD 38
 Long wall - short wall method Centre Line Method
• Measure Long walls ‘out to out’ GL • Calculate the total centre line length
• Measure short walls ‘in to in’ 800 • Multiply by breadth to get area
• Multiply by breadth to get area 500

500 500 500 500

500 500

2000 2000

500 500

5000 5000

• Long Wall = 5+5 =10 m • Centre line length = 2×(5-0.5)+2× (2-0.5)

• Short wall = 1+1 = 2 m = 12m
• Total length = 12 m • Volume = 12×0.80×0.50 = 480 cum
• Volume of excavation = 12×0.80×0.50 = 480 cum

Dr. Sahil Bansal, IITD 39

 Example

Dr. Sahil Bansal, IITD 40

 Example - Detailed Estimate (Boundary wall of a plot)
Brickwork
3000
(1:3 mortar)
3000 230 DPC

Plinth Level

200 Ground Level

7000 200

400 500

200 700

1000 mm opening
PCC (1:4:8)
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 Example - Detailed Estimate (Quantity take-offs)

Item Item No. L (m) B (m) H (m) Quantity Unit Remarks

No.
1 Earthwork in excavation 1
2 PCC 1
3 Brickwork in foundation
First footing 1
Plinth wall 1
4 DPC 1
5 Brickwork in superstructure 1
6 Backfill 1

Note:
• Excavation to be calculated allowing 200 mm on both sides beyond minimum width requirement.
• Original and final ground levels on both sides are same.

Dr. Sahil Bansal, IITD 42

 Example - Detailed Estimate – (Bill of quantities, BOQ)
The BOQ is a document showing a list of everything needed to build something and how much each item will cost.

Item No. Item Quantity Unit Unit Rate (Rs) Amount

1 Earthwork in excavation m3 5
2 PCC m3 700
3 Brickwork in foundation m3 650
4 DPC m2 980
5 Brickwork in superstructure m3 625
6 Backfill m3 6
Total

What is the construction cost in per meter length of 1m deep foundation (up to plinth level) ?

What is the construction cost in per meter length of 3m high wall?

Dr. Sahil Bansal, IITD 43

 Damp proof course (DPC)
A damp-proof course (DPC) is a barrier through the structure
designed to prevent moisture rising by capillary action

Dr. Sahil Bansal, IITD www.efflock.com.au https://www.youtube.com/watch?v=sIrXUY9TscE 44

 Rate Analysis - Fixing of rate per unit of an item
The rate per unit of an item includes the following:
1. Quantity of materials & cost: The requirement of
materials is taken strictly in accordance with
standard data book (S.D.B). The cost of these Quantity
includes first cost, freight, insurance and Take offs

transportation charges.
2. Cost of labour: The exact number of labourers
Skill,
required for unit of work and the multiplied by the Productivity
wages/ day to get of labour for unit item work.
3. Cost of equipment: Some works need special type Method,
of equipment, tools and plant. Productivity
4. Other charges: Overheads, Profits, Margins: To
meet expenses of office rent, depreciation of Percentage
equipment salaries of staff postage, lighting ...

Schedule of rates provide a useful set of guidelines

Dr. Sahil Bansal, IITD 45
 Estimation- Labour Cost
Types of Labour
• Salaried Employees
• Base Salary and Wages
• “Payroll Burden Items”
• Insurance
• PPF contributions
• Allowances for transportation etc
• Area premium pay
• Overtime (Time and a half)
• These costs are usually included in job overheads
• Hired Contract Workers
• Hourly or daily wage rate
• “Payroll Burden Items”
• Insurance
• Overtime (Time and a half)
• Travel Time costs
• These costs are usually included directly in job costs

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 Example- Labour Cost
• A steelworker works 10 hr/day, 6 days/week
• A base wage of Rs. 100 per hour is paid for all straight time work, 8 hours/day, 5 days/week
• An overtime @ rate one-half is paid for all hours over 8 hours/day, Monday through Friday, and @ rate
double time is paid for all Saturday work.
• The insurance rate to be paid by the employer is Rs 12.5 per Rs.100 of base wage.
• The employer also must pay a tax of 10.65% of actual wage
• Fringe benefits of Rs. 12 per hour are also to be paid.
• Calculate the average hourly cost to hire the steelworker , if weekend work is and is not considered.

• Next suppose there are five steelworkers in a crew and the crew can place 3000 kg per 10 hour day of
reinforcing steel, what is the cost of labour per kg of steel in place, if weekend work is and is not
considered.

Dr. Sahil Bansal, IITD 47

 Actual hours worked = 60
Wage hours = (5  8)+(5  2 1.5+1)  (10  2) = 75
Total pay per week = 7500
Average hourly Wage = 7500/60 = 125
Tax paid @ 10.65% on actual wage = 125  0.1065 = 13.3
Insurance @ 12.5% on base wage = 100  0.125 = 12.5
Fringe Benefits = 12
Average Hourly cost = 162.8

Dr. Sahil Bansal, IITD 48

 Estimation- Equipment Cost
Equipment Costs are of two types:
• Ownership Costs
• Depreciation
• Interest Charges
• Insurance Charges
• Taxes/Licenses/Permit Fees
• Rental/Lease Fee
• Operations Costs
• Maintenance and Repair
• Fuel, Oil, and Lubrication

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 Example - Equipment Cost
What is the output of this equipment.
• A backhoe with 1 cum bucket is capable of handling 3 bucket-loads per minute under ideal conditions.
However, on a given job, the average volume per bucket may be only 0.8 cum and the backhoe may be
operating only for 45 min/hr.
• For these operating conditions, what is the hourly average ideal output and average effective output?

What is the per hour rate that shall be charged for this equipment?
• The initial cost of a piece of a backhoe is Rs.25 lakhs. The estimated salvage value of the equipment is Rs.9
lakhs. The useful life of the equipment is 10 years. The equipment will operate 2000 hours per year. The
cost of one set of tires is Rs.4 lakhs.
• A new set of tires will be replaced at the end of every 3 years of operation. In addition a repair work of cost
Rs.4.5 lakhs is expected at the end of year 6. The interest rate is 8% per year. Find out the total cost per
hour for the construction equipment considering time value of money.

Dr. Sahil Bansal, IITD 50

 Example: Rate Analysis of Concrete
What is the rate per cu.m for providing and laying in position cement concrete nominal M15 mix, that is, 1:2:4 mix (one
volume cement: two volume fine aggregate: four volume graded stone aggregate 20 mm nominal size).
• Absolute Volume Method: volume of fully compacted concrete is equal to the absolute volume of all the materials of
concrete, namely, cement, sand, coarse aggregate and water.
• Approximate Methods: dry volume of materials is equal to 1.54 times the wet volume of concrete due to voids present
in sand and aggregate in dry state

SG of cement = 3.15 Unit rate of cement at site = Rs 300 / bag

SG of FA = 2.6 Unit rate of FA at site = Rs. 140/ cu.m
SG of CA = 2.6 Unit rate of CA at site = Rs. 160 / cu.m
Bulk Density of cement = 1500 kg/m3 Unit rate of water at site = --
Bulk Density of FA = 1700 kg/m3 Vibrator Hire Charges = Rs. 12 / cu.m
Bulk Density of CA = 1650 kg/m3 Mixer Machine Hire Charges = Rs. 220 / cu.m
Weight of 1 bag of cement = 50 kg
Volume of 1 bag of cement = Labour for 10 cum of concrete (preparing and laying)
2 Nos. Mason II Class Rs. 225.00 each/day
Overhead @ 10% 3 Nos. Mazdoor I Class Rs. 150.00 each/day
Profit @ 10% 5 Nos. Mazdoor II Class Rs. 120.00 each/day

Dr. Sahil Bansal, IITD 51

 Material ratio by vol (dry) = 1: 2 : 4
Material ratio by mass (dry) = 11500 : 2 1700 : 4 1650 = 1: 2.67 : 4.4
masscement massFA massCA masswater
Vconcrete = + + +
cement  FA CA  water
masswater = w / c ratio  masscement

Dr. Sahil Bansal, IITD 52

 For 10 cu.m
SNo. Item Quantity Units Rate Units Rate Amount
1. Cement Nos. 300 Bags(50kg)
2. FA cu.m 140 cu.m
3. CA cu.m 160 cu.m
4. Vibrator 10 cu.m 12 cu.m
5. Mixer 10 cu.m 220 cu.m
6. Labour
Mason II Class 2 No 225 Day
Mazdoor I Class 3 No 150 Day
Mazdoor II Class 5 No 120 Day
Total Amount (10 cu.m)

Total Amount 1 cu.m, a =

10
Cost 1 cu.m = a 1.10 1.10 =

Dr. Sahil Bansal, IITD 53

 Wastes in Estimation
• Due to industrial standards bricks, wood, steel etc come in standard dimensions. Need to
be cut, resulting in some wastage
• Due to material handling and installation
• Site management and congestion
• Quality of equipment and tools
• Worker skills
• Storage and theft

Dr. Sahil Bansal, IITD 54

 Accuracy of Estimates

• As the project progresses, the amount of unknowns and uncertainties decreases, while the level of details
and the project information increases.
• In this way, the accuracy of the estimate improves as it moves from conceptual to detailed estimate.

Dr. Sahil Bansal, IITD 55

Accuracy of Estimates

Estimate Type Remarks Methods of Estimation Accuracy

Rough order of Used for go/no-go with a • Past experience, historical values, ±60%
magnitude estimate project, little or no design rules of thumb, …
(Client’s) information available
Conceptual/Preliminary Final go/no-go • Functional Unit Estimate ±40%
Estimates (Client’s) • Plinth Area Method
• Cubic Meter Method
Engineers/ Detailed Here, complete structural • Unit costs for bill of quantities -15%
Estimate drawing, specifications and rate +30%
(Client’s)
of the items are necessary
Detailed Estimate -5%
(Contractor’s) +10%
Project closure estimate • Final Cost ±0%

Murphy’s Law: Things will go wrong in any given situation.

 Project Cost
Estimation

Client / Owners Contractors

Perspective Perspective

Owner’s Purpose of Cost Contractor’s Purpose of Cost

Estimation Estimate
• Making investment decision • Determine project cost for
in the conceptual stage. bidding purpose and profit.
• Negotiate and finalize the • To implement cost control
contract at the implementation measure.
phase. • To develop data base for that
• To implement cost control can be used for future project.
measures.

Dr. Sahil Bansal, IITD 57

 Client’s Detailed Estimate
• The Client’s Detailed Estimate reflect the amount that the client considers fair and reasonable and is willing
to pay for performance of the contemplated work.

• Client’s Detailed Estimate serves as the benchmark for analysing bids and is an essential element in the
project approval process.

• Estimating the work done for issuing the contractor payments.

• Under-estimating causes project delay while additional funding has to be arranged to meet the contract
costs.

• On the other hand, over-estimating causes inefficient use of funds that could be used for other projects.

Dr. Sahil Bansal, IITD 58

 Contractors Perspective
• The decision of a contractor is based on its Detailed Estimate.

• Estimating the work done for demanding the work completion payments.

• Under-estimating can lead to monetary losses at the time of execution.

• On the other hand, in case of over-estimating the likelihood of winning the bids is very less.

Dr. Sahil Bansal, IITD 59

 Some insights on Construction Estimates
• A very important part of a construction project

• Mistakes in estimation can ruin a project/company

• Not rocket science, however it requires discipline and care

• Some of the most experienced people are in the estimating department “building the project in your head”

• When costs are overestimated, the owner ends up paying more than necessary or may decide not to proceed
with the project.

• Contractors can also face negative consequences if they overestimate project costs: they are likely to lose in
competitive bidding or they may be regarded as scammers, hurting their reputation.

• When costs are underestimated, there are many unforeseen expenses during the construction phase. Based
on how the contract is structured, these costs may affect the owner, the contractor, or both. There have been
cases where developers or contractors end up bankrupt due to drastic underestimation in a large project.

Dr. Sahil Bansal, IITD 60