Sunday, December 26, 2010

Thumbrules for Estimating Quantities in Residential Buildings

Expert estimators are able to work out the quantites of concrete, steel, brickwork, plaster and finishing material based on the total built-up area of a residential building without even looking at the building plans.

So here's a rough guide on working out the quantites for a residential building of approx 1 lakh square foot built-up area.

Concrete-  Approx 4500 cum of concrete would be required for the structural frame of the building. The thumrule to follow is 0.045 cum of concrete per square foot of built-up area. This quantity would increase slightly for a building having basements as extra concrete would go in the raft, retaining walls and to the ramps to the basement.

Rebar- Approx 540 tons of rebar would be required. The thumbrule to follow is 120 kg of rebar per cum of concrete. Highrise buildings require more steel in the colums and the amount of steel per cum of concrete would increase with the height of the building.

Brickwork - Approx 1.3 lakh sq feet of wall would be present in the building with 1 lakh square feet area. However, the total area of the walls would depend a lot on the size of rooms.

Plastering and Paint Area - is approximately 3 times of the brickwork area . Note that this also includes ceiling and staircase plastering.

These numbers only apply to large residential towers and not to small housed and bungalows. Please apply these numbers with caution as they may vary for your particular project.

Tuesday, December 14, 2010

Monthly Site Running Costs - Overheads

Salary of Staff Deployed at Site
Accomodation Expense for Staff
Staff Welfare Expense
Vehicle Running and Transportation Charge (local)
Head Office to Site Travel Expense
Water Charges
Electricity Charges
Telephone and Internet Expense
Office Stationary and Furniture Expenses

Wednesday, December 1, 2010

Various Types of Waters at Power Plants

Raw Water -  Water coming externally from a cross country pipeline into the plant and is stored in the raw water reservoir.

Clarified Water - Raw water after Primary Treatment becomes Clarified Water

DM Water - Part of the Clarified Water is sent to the DM Plant for removal of dissolved salts. This water is used for filling up the boiler is called Boiler DM Water. A part of DM water is also used for cooling the various pumps and equipments in the BTG area and is called DM Cooling Water.

Cooling Water - A part of the Clarified Water is sent to the cooling water forebay for cooling of the condensor. Steam exiting the turbine is condensed into water in the Condensor with the help of Cooling Water

Auxillary Cooling Water -A part of the Cooling Water is used to cool the DM Cooling water via Plate type Heat Excanger. The water used to cool the DM Cooling Water is called Auxillary Cooling Water

Potable Water - is used for drinking and cooking purposes

Service Water is used for generally cleaning, washing, firefighting etc is called Service Water

About Pipes - Part 1

Pipes are generally made of  metal, plastic or concrete.

Metallic pipes are of Cast Iron, Galvanized Iron, Carbon Steel, Mild Steel, Stainless Steel, etc
Plastic Pipes maybe of PVC, HDPE, FRP etc
Concrete Pipes are made of various concrete mixes

Mettalic pipes maybe manufactured by extrusion (also called seamless pipes), centrifugal casting and spinning or welding.

Pipes generally are classified by their Nominal Bore which is their Outer Diameter and by Pipe Schedule which is the thickness of the pipe shell.

Pipes may be joined together by Welding, Flanging or Threading.

If pipe is joined by welding ( either Butt Welding or Socket Welding) then radiographic inspection of the welded joint would be required by the client.

If a mettalic pipe is to laid underground then the pipe must be protected from corrosion by wrapping and coating and also by cathodic protection.

Sunday, October 24, 2010

Courses in Construction and Related Fields

Many Indian institutes offer courses related to construction beyond your normal Btech courses.
Some of the institues are

1. NICMAR - National Institute of Construction Management and Research in Pune.
Offers many courses in Project Management, Construction Management, Planning, etc
Check it out at

2. Indian Green Bulding Council conducts an exam for candidates wanting to certify themselves in Green Building Design.
Check it out at

3. Sahayadri Engineering Academy specializes in courses in Construction Technology.
    Check it out at

4. Project Management Institute is an internationally recogonozed body offering PMP certification which can help budding project managers.
Check it out at

5. National Power Training Institute is an highly accaimed institute offering courses and trainings to students wanting to make a career in the power industry.
Chek it out at

Saturday, October 16, 2010

Water and Sewage Treatment Process

Sewage is referred to waste from the bathrooms and kitchens of households.
Water is treated for making it fit to drink for human consumption.

The three stages of treatment are:

1. Primary Treatment
a. Screen Filtration
       Large and visible impurities are removed from water/sewage by passing it through mettalic screens of
       decreasing sizes. Items such as small gravel, pieces of leaves, etc are filtered through this method.

 b. Sand Filter
    Water/sewage is then passed though a sand filter to remove particles of very small sizes. The sand is generally compacted very tightly in the filter and does not allow any undissolved particles to get through it.

2. Secondary Treatment
    Generally water contains dissolved salts (inorganic impurities) and also fats and oils (organic impurities)
To get rid of dissolved salts, Reverse Osmosis (R.O.) technoloy is used. Chorides and carbonates of soduim, calcium and magnesium are removed through the R.O technology. Incase water with almost zero dissolved salts is desired then a De-Mineralization plant would have to used. This plant is generally used for boiler water but not for human consumption.
 To get rid of dissolved fats and organic matter, water is allowed to stand still and bacterial growth is allowed which eats away the organic matter and then settles at the bottom of tank as sludge.
Infact alum is added to the tank which encourages the sludge particles to stick together by a process called flocculation and settle at the bottom of tank.
Clarified water is then obtained from top of the tank.

3. Tertiary treatment
     Clarified water still contains bacteria and viruses which can make humans sick. Hence the clarified water is then chlorinated or treated with ozone to get rid of the pathogens.
At homes we use UV rays in the Aquagaurd to achieve the same effect.

Technolgies are being developed to convert sludge into bio-gas as sludge is rich in organic matter.

Tuesday, September 14, 2010

Removal of Shuttering from Structural Elements

Many times, I have been asked what is the ideal time for maintaining formwork after casting of a structural element such as column, wall, beam and slab.

Below is only a general guideline for removal of formwork and not to be followed without the approval of your structural consultant.

a) Removal of formwork from walls, columns and vertical surfaces - 24 hours

b) Removal of formwork from slabs while keeping the props - 4 days

c) Removal of formwork from beams while keeping the props - 7 days

d) Removal of props under slabs
1) Slab span upto 4.5m - 7days
2) Slab span above 4.5m - 14 days

e)Removal of props under beams
1) For beams upto 4.5 m - 14 days
2) For beams above 4.5m - 21 days

Please remember after removal of formwork, proper curing of concrete is really important.

Power Sector Outook

Currently the installed capacity of India is 160,000 MW of which nearly 80 percent is with PSU's and govt bodies and 20 percent is with private sector.

In 2009, India was able to add about 10,000 MW to its capacity.
The good news is that the ministries are taking a very active role in fast tracking projects and its likely that another 10,000 MW would be added by end of 2010. More then 40 private projects have been cleared and would be under construction soon. Typically it takes 3-5 years for a thermal power plant to be operational once the construction starts.

Major players in Power Sector:
NTPC is the largest player with installed capacity of 32,000MW
Tata Power and Reliance Infra are the major private players.
NHPC is the largest player in hydropower space.

For the first time Ultra Mega Power Projects (UMPP) ie power plants with 4000MW capacity have been sanctioned and four of the UMPP's are expected to be commissioned by 2015.

The future of power sector looks very positive.

Friday, September 10, 2010

Top EPC Contractors in India

1. Larsen and Toubro
2. Punj Lloyd
3. Jaypee Associates
4. Lanco Infratech
5. Nagarjuna Constructions
7. Simplex Infrastructure
8. GMR
9. Gammon India
10. HCC
11. Tata Projects
12. Shapoorji Pallonji
13. GVK
14 Shobha Developers
15. IRB
16. Tata Projects
17. Siemens

Quality checks to be kept in mind while casting of concrete

The following points must be kept in mind before casting of any structural member

1. Rebar details must be correctly followed as per drawings.

2. Rings/stirrups provide strength to columns and beams and prevent the concrete from spreading out and cracking. Hence rings should not be missed out as it could cause structural failure . Its a good idea to get rings pre-fabricated from contractor who specializes in this kind of a job

3.Ring spacing along the column or beam rebar must be correctly followed.

4.Cover blocks must be placed all around the rebar to prevent the rebar from touching the shuttering

5. Ensure that the shuttering alignment is correct and shuttering is vertical.

6. Make sure to take atleast 2 samples of concrete before casting for 7 day and 28 day testing. Fill the moulds with concrete and cure them before sending them to the quality lab.

7. Do an onsite slump test of concrete by using a slump cone

8. Make sure that the inner sides of shuttering material are smooth and smeared with shuttering oil

Tuesday, September 7, 2010

Concrete vibration is important

Vibrating concrete is a must so that concrete can achieve its design properties

Vibrating concrete makes it more fluid and hence it flows into the corners of the formwork

Air-gaps in concrete are significantly reduced and results in a more consistent density of concrete both at top and bottom

However over-vibrating the concrete will result in seggregation of aggregates.

One must be careful that vibrator does not disturb the rebar arrangements especially in areas where rebars are very dense.

For optimum compaction the frequency of the vibrator should be between 10,000 to 12,000 vibrations per minute.

What is BIM and 3D, 4D and 5D ?

Building Information Modeling is the process of converting the 2D drawings into a 3D model on the computer. The structural, architectural and mep drawings are used as inputs to create an very accurate 3D model.

Archicad and Revit are the most popular softwares used for BIM modeling.

This model can be used for:

1. For spatial visualization of the building

2. For doing constructiblity analysis
eg if the slab level shown in architecural drawings and structural drawings are different or if a pipe if going through a lift shaft, then BIM would be able to identify that.

3. For generating sections from anywhere in the building. Time is saved as the BIM software does this automatically.

4. Preparing Bill of Quantities from the BIM model is fast. Take-off sheets can also be prepared. This is infact called the 4D or the cost.

5. The items in the Bill of Quantities can be exported to a scheduling software such as Primavera, MS Project or Vico Control to sequence the construction activities. The tasks have location data and quantity data already built into them, so scheduling is faster and more accurate. This is called 5D.

6. Future add-ons to BIM sofware would include structural analysis, energy analysis for calculating tonnage of air-conditioning required, preparing BBS for pre-fabrication, etc.

I have used BIM softwares on a few project and feel that a big change is underway in the construction industry.

Sunday, September 5, 2010

Types of Paints

Paints can be mainly classified as

1. Distempers
Dry Distempers are dry powder like paints and are mixed with water.
Also referred to as white-wash.
Oil Bound Distempers comes in liquid form and will last for 3 to 4 years
at the most. Its much cheaper than a emulsion.

2. Emulsions
Emulsions come as Matt, Semi-Glossy and Glossy and are also referred
to as plastic paints. Some paint companies refer to the finish as
Regular, Eggshell/Satin and Silk. Emulsions come pre-mixed with water from the paint company

3. Oil or Enamel Paints
Are very thick paints to be used on metals or woods. They cannot be
be mixed with water. They have a very strong paint like smell and have
Volatile Organic Compounds.

Boiler Milestones for Thermal Power Plants

1. Completion of boiler foundation
2. Steel structure for boiler support
3. Boiler drum lifting
4. Hydro-test for leakages
5. Boiler light-up
6. Acid Cleaning
7. Steam blowing
8. Safety valve floating
9. Synchronization with oil
10. Synchronization with coal

Saturday, September 4, 2010

Important Balance of Plant Packages for Thermal Power Plants

1. Coal Handling System
Coal is the fuel used to heat up the water in the boiler to produce steam. The coal delivered to the site is stored in bunkers and delivered to the pulverizer by conveyor belts. The pulverized coal is further transferred to the ball mill where its is converted into a powder form. This entire system is called the coal handling system of the power plant.

2. Ash Handling System
Burnt coal produces bottom ash and fly ash. The bottom ash is falls through the grate of the furnace into a silo where it is mixed with water to produce ash slurry. This slurry is then pumped out of the boiler furnace into an ash pond. The fly ash moves along with the flue gases and is trapped by an electrostatic precipitator. The trapped ash is then pnuematically sent to the ash storage area.

3. Cross Country Pipeline
Water for the power plant generally comes from a river, sea, lake reservoir or an STP plant of a city. The distance of water source to the power plant may be quite large and hence a cross-country pipe line is required along with a pumping station.

4. Water Treatment Plant
Water required by the power plant needs to be free of any suspened particles as well as dissolved salts. Hence the water is generally passed through a pre-treatment plant, RO plant and a De-mineralisation plant before being used in the boiler, turbine, etc.

5. Cooling Tower
Cooling water is required to convert the exhausted steam from the turbine back into water to create back pressure and improve thermal efficieny of the plant.Hence cooling tower is required to cool the heated water passing through the condensor.

6. Switchyard
The electrical network where the power is transferred along different routes.

7. Railway Siding
Coal needs to transferred from the coal mine to the power plant by means of a train. The train enters the power plants and dumps the coal into a underground bunker. Power plant owner needs to erect the railway tracks for the train to reach the power plant.

8. Transmission Line
The power needs to be evacuated by means of high voltage transmission line to the purchaser of power such as State Electricity Board.

Friday, September 3, 2010

Plant and Machinary Required at Construction Site for Civil Works

1. Diesel Generator for electricity of site office, area lighting, water pump,machinary, etc
2. Water Pump for drawing water from the boring well
3. Excavator
4. Rebar Cutting Machine
5. Rebar Bending Machine
6. Dewatering Pump
7. Hydra Crane of 12 T
8. Tractor with Trolley for moving shuttering material
9. Vibration Plate Compactor for back-filling of soil
10. Total Station for determining levels and aligning columns with each other
11. Tower Crane for height work
12. Batching Plant for making concrete
13. Concrete Pump
14. Field Junction Boxes and lots of cables for lighting

Management Structure of Construction Site

The typical management structure of a project at site would be:

1. Project Manger
2. Civil Engineer
3. Mechanical Engineer
4. Electrical Engineer
5. Plumbing Engineer
6. Store Manager
7. Quality Manager
8. Safety Manger
9. Time-office Manager
10. Admin and Accounts

Sunday, August 22, 2010

Footing Rebars

The process for tying rebar for the isolated footings is:

1. Lay the bottom mat on the PCC
2. Tie the vertical rebars to the bottom mat
3. Place the stirrups around the vertical rebars
4. Tie the top mat of the footing

Monday, August 16, 2010

Top 10 Real Estate Companies in India

1. DLF
2. Unitech
3. Raheja Developers
4. Ansals
5 Hiranandani Constructions
6. Mantri Constructions
7. Jaypee Housing
8. Kalpatru
9. Kumar Builders
10. Omaxe

Monday, August 2, 2010

Types of Valves

lvelvvBasically there are 4 types of mechanical valves:

1. Flow Regulating Valve - The purpose is to control the amount of flow in the pipe. Eg Butterfly or Globe Valve

Butterfly Valve
Globe Valve

2. Stop Valve - To completely stop or start the flow of fluid. These valves are good for "On" and "Off" application but poor in controlling the amount of flow. Eg Ball Valve or Gate Valve

3. Check Valve - Allows the fluid to flow in only one direction and prevents backflow of fluid

4. Pressure Regulating Valve - If the pressure in the piping system exceeds a certain amount, then the valve opens to relieve the pressure in the sytem. Eg Steam bypass valve

Generally the valves are color coded as per the fluid they are carrying
White Color - Steam
Blue Color - Water
Yellow - Fuel/oil
Dark brown- Sewage

Sunday, July 25, 2010

Classification of Power Plants

Thermal Power Plants
1. Coal Based Power Plants
2. Gas Based Power Plants
3. Oil Based Power Plants

Hyrobased Power Plants

Nuclear Power Plants

Windbased Power Plants

Solar Power Plants

Monday, July 5, 2010

Oil and Gas Sector Classification

The Oil and Gas Sector can be classified as:
1. Exploration
Companies which explore the depths of earth to locate oil and gas
deposits. This also involves looking under the sea bed.

2. Drilling Oil Wells
Wells of depth of upto 10km below the surface of the earth may have
to be dug for pumping the oil to the surface of the earth. Offshore
wells are called oil rigs.

3. Piping
Oil and Gas may have to piped for long distances from the oil well to
the refinaries. Also post refining, oil and gas may have to pumped
further via pipelines for distribution via road, rail and sea.

4. Refinary
Converts the crude oil and gas into fractions such as petrol,
diesel, naptha, bitumen, etc.

Wednesday, June 30, 2010

Land Measurement Units Followed in India

Land measurement units vary a great deal across India from region to region.
The following traditional units are used most frequently in land transactions.

Katha  = 80 square yards
Nalli    = 240 square yards
Bhigha = 1600 square yards
Acre    = 4800 square yards

Monday, June 28, 2010

Highway Construction

Highways are divided into National Highways, State Highways and District Highways.

Major types of work involved are:
1. Constructing a new highway
2. Expansion of a highway eg 4 laning of an existing 2 lane highway
3. Repairing of a highway

The major items of work are:
1. Topographical Survey of the area
2. Road Alignment and Grading to minimize cut and fill
3. Earthwork in Mass Excavation
4. Earthwork in preparation of Embankment
5. Preparation of Subgrade
6. Laying of base course
7. Laying of wearing course
8. Laying of dense bitumen macadam
9. Laying of premix carpeting.

There are number of other activities such as laying of curbstones, road siding for protection, painting of road, road signage, medians, etc.

Monday, June 7, 2010


Galvanizing is process of depositing a layer of zinc coating on top of steel or iron to prevent rusting and improve the lifespan.
The thickness of zinc coating is measured in microns.

The two basic methods of achieving galvanizing are:
1. Electroplating
2. Hot-dip Galvanizing

Hot-dip galvanizing is preferred as it gives better quality of coating.
Ducts, pipes, fixtures, etc are some of the common items which are galvanized.

Thursday, June 3, 2010

Softwares Used in Construction Industry

2D Drafting Software: Autocad , ZW Cad

Rendering Software: Photoshop, Artlantis, 3D Max

BIM Softwares: Archicad, Revit

Structural Analysis Software: STAAD Pro, Etabs

Piping Software: Ceasar

Project Scheduling Software: Primavera P6, Microsoft Project

ERP Software: SAP modules of Project Systems and Material Management

The most useful software of all: MS Excel :)

To puchase these softwares in India, contact

Adroitec Information Sytems Pvt Ltd
D-194 (2nd Floor)
Okhla Industrial Area, Phase - 1,
New Delhi 110020

Tel: +91 11 47666444 , 41609231-33
Fax: +91 11 41609230

Wednesday, June 2, 2010

Reducing Costs in Construction

1. Freezing the architectural and structural drawing set by a certain date before start of construction. Starting the construction process without freezing the architectural and structural drawings could almost double the cost of the construction. Any design change in the middle of the project is very very expensive.
2. Minimizing discrepancies between the structural set and architectural set of drawings.
   Avoids rework and change orders. Use a BIM tool such as Archicad or Revit to create a 3D model of the building

3. Decisions needs to be taken on
   a) RMC or Batch Plant
   b) Shuttering - Wooden or metal
   c) Floor Plate should be divided in how many zones for optimal scheduling of rebar, shuttering and  concreting
   d) How many sets of shuttering will be required.
   e) Capacity of Batch Plant and location of Batch Plant w.r.t plate
   f) Tower Crane Height and Capacity.
      After how much time will extra tower crane be required.
      Location of tower cranes

4. Scope and Liablities of Owner and Contractor must be clearly defined and battery limit for the project must be eastablished at the earliest.

5. Siginificant savings maybe achieved in procurement of materials from local suppliers

6. Using precast walls in combination with frame structure

7. Use-fly ash bricks and fly ash concrete

Saturday, May 22, 2010

Waterproofing Basics

Waterproofing between Raft and PCC - membrane protection

Waterproofing in Toilets and Kitchens - liquid compound mixed with concrete (Sikka)

Waterproofing in Roof - mud fuska, bitumen coating, membrane protection ( EPDM sheet)

Waterproofing in concrete Water Tanks or Swimming pools - crystalline coatings

Waterproofing of External Walls from rain - make cavity walls, water-proof plaster

Thursday, May 20, 2010

Plastering Deductions as per IS Code 1200

For small opening up to 0.5 m2 area, no deduction in plastering is made

For opening of size 0.5m2 to 3m2 area, deduction is made on one face of the wall.

For openings of size above 3m2, 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

For such cases, its best to follow actuals then following IS code while preparing R.A bills.

Ceramic and Vitrified Tiles

Tile can be classified as Ceramic and Vitrified.

Vitrified tiles are of much better quality then Ceramic Tiles.

Ceramic tiles are glazed only on top and if top is destroyed, then the tile would lose its color.

Vitrified tiles are uniform throughout and much more durable, less porous and scratch-proof.

Generally for the wall, ceramic tiles maybe used, but for floors vitrified tiles are prefferable.

Ceramic tiles can be manufactured locally, however vitrified tiles require high budget industrial equipment

Steel Bars in India

2 comon types of steel bars used are
  • Mild steel bars conforming to IS: 432
  • Cold-worked steel high strength deformed bars conforming to IS: 1786 (grade Fe 415 and grade Fe 500)
The numbers 415 and 500 indicate yield stresses 415 N/mm2 and 500 N/mm2 respectively

Grade Fe 415 and Fe 500 is being used most commonly nowadays because of higher yield stress and bond strength resulting in saving of steel quantity.This has limited the use of mild steel bars

Some companies have produced the thermo mechanically treated (TMT) and corrosion resistant steel (CRS) bars with added features.

Wednesday, May 19, 2010

Rebar Weight Formula

Rebar weight is defined in kg/m

Formula for measuring weight of steel bar = Square of Diameter / 164

Eg for 12mm rod

(12*12)/164 = 144/164 = .888 Kg/M

Tuesday, May 18, 2010

Article on Virtual Construction by Mr Suresh Gupta

An interesting article on Virtual Construction or BIM technology being used by a lot of Construction firms today.

Storage of Cement at Site:

Its very important to have proper storage for cement at site. The following points should be
kept in mind
  • The plinth of the store shold be about 450mm above from the NGL.
  • The cement bags should be placed on the wooden planks 200mm above the plinth.  
  • The store should be air tight.
  • The stack of cement should be coverd with Polythene.
  • FIFO system of inventory should be followed.

Monday, May 17, 2010

Some ways to judge the quality of Cement

1. Bag should have BIS mark.
2. Cement should be smooth and silky when rubbed
     between thumb and forefinger. (Fineness)
3. No lump should be visible
5. Check manufacturing date for freshness of cement
6. Packing should be done in polythene bags
7. Cement should not feel warm when hand is inserted in bag

Saturday, May 15, 2010

About Sand in Construction

  • Sand is required for making concrete, mortar and plaster.
  • Fine Sand is also referred to Jamuna sand in Delhi
  • Sieve Analysis is used for testing the Sand for Grading
  • Silt Content Test is important. Sand should have minimum silt content. This must be done at the Initial Stage itself.
  • If any Chemical impurities may possibly present, it should be tested for that also.

Some Important Terms in Contracting for Construction

Earnest Money: Is the money paid by the Contractor to the Owner at the time of submission of bid to show that the Contractor is serious about executing the works if the contract is awarded to him. For those contractors which are not successful at securing the bid, the earnest money paid by them is refunded.

Security Deposit or Performance Gaurantee: Money payable by the Contractor to the Owner in the form of a Secured Bank Gaurantee to protect the owner in the case of Contractor either abandoning the works or not executing the works as per the specifications of the contract. Performance Gaurantee may be in the range of 2 to 4 percent of the total contract value.

Retention Money: Money held back by owner(say about 5%) from the monthly bill of the Contractor to protect himself against any defects. This money is paid back at the end of defects liablity period

Defects Liability Period: is the amount of time from completion date that the contractor is liable for defective construction

Depreciation: is the decrease in value of any asset.

Depreciation has a major impact on the taxation. Depreciation is accepted as an expense in the balance sheet by the tax authorities. Depreciation increases operating expenses thereby reduces profit and income tax. However, depreciation is not an actual cash outflow from the company.

Depreciation on construction machinery helps a construction company save tax.

Liquidated Damages: is the penalty charged by the owner if the contractor does not finish the works by the approved schedule. Generally its upto 5% of the contract value.

Friday, May 14, 2010

Construction Cycle

  • Land Acquisition
  • Feasibility Study for a Particular End Use in Mind
  • Land Usage Approval for Residential, Commercial construction i.e. N.A (Non Agriculture Land) and N.O.C
  • Design - Approved by PWD office at Vikas Sadan, New Delhi
  • Environmental Clearance ( Environmental Impact Assessment Report) And Clearance by Fire Officer
  • BOQ Preparation or Costing of Project (must include overheads)
  • Tender Preparation and Inviting Tenders
  • Contract Awarding and Signing of MOU's
  • Approval of Construction Schedule
  • Construction Start and Monitoring
  • Construction Completion and Decommissioning

Types of Construction

Construction Industry can be broadly classified as:
  1. Residential Construction
  2. Commercial Construction: This includes malls, hotels, offices, etc
  3. Infrastructure Construction : This includes roads, dams. bridges, flyovers etc
  4. Industrial Construction: This includes power plants, steel mills, chemical plants, etc

Thursday, May 13, 2010

Types of Contracts

  • Fixed Fee or Lump sum Contracts (with provision for change orders)
  • Item Rate Contracts
  • Cost Plus Contracts with GMP
  • Percentage Rate Contracts with Guaranteed Maximum Price (GMP) 
  • Contract between a Govt body and a private organizations is called PPP or Public Private Partnership.
  • Supply and Erection Contracts

Components of a Centralized Air Conditioning System:

  1. Chillers

  2. AHU
  3. Ducts

  4. Water Pipes

  5. Pumps

  6. Cooling Towers

  7. Diffusers, Grills, Registers etc

  8. Mechanical Dampers, Fire Dampers, Smoke Dampers, Thermostats

Tendering Cycle Sequence

   1) Notice Inviting Tender Date

   2) Date of Bid Submission

   3) Date of Bid Opening

   4) Award of Contract

   5) Date of Notice to Proceed

   6) Date of Onsite Construction Presence

About Bricks

Indian Standards in Brickwork
  • Nominal Size of Brick (in mm) = 230 x 115 x 75
  • Nominal Size of Brick (in inches) = 9 x 4.5 x 3
  • Number of bricks per cum of brickwork = 1/(0.230 x 0.115 x 0.075) = 504 bricks
  • Number of bricks per sqm of half-brick thick wall = 1/( 0.230 x 0.075) = 58 bricks 
  • Mortar required per cum of brickwork = 0.25 cum
Brick Types:
  • Normal Bricks
  • Fly-ash Bricks 
  • Cement Hollow Blocks ( 400mm x 200mm x 200mm) (These blocks are generally hollow, else they would be very heavy to lift)

Basics of Concrete

Concrete Mix Ratios - Cement : Fine Aggregate : Coarse Aggregate
  • M10 =1:3:6
  • M15= 1:2:4
  • M20 = 1:1.5:3
  • M25 = 1:1:2
The numbering denotes strength of the concrete. The higher the number the higher the strength.
For M30 and above, only design mixes are used.

  • These mixes are based on OPC 43 cement. If OPC 53 or any other grade of cement were to be used then these ratios would change.

  • M10 means that the concrete mix should have a compressive strength of 10N/mm2 and so on

  • These ratios are based on a volumetric mix and not a mix based on weights of the ingredients

  • IS Code 456 deals with the various grades of concrete

  • RMC is Ready Mix Concrete supplied by the RMC plants to the construction site in transit mixer trucks

  • Cost of Ready-Mix-Concrete including transportation is Rs 3000 per cum

  • As the water to cement ratio increases, the strength and durability of concrete decreases. However adequate water to cement ratio must be used for workability of concrete.
Concrete is tested by:
  1. Cube Test for strength
  2. Slump Test for workability

Tuesday, May 11, 2010

Types of Cements available in India

Ordinary Portland Cement (OPC): Also referred to as grey cement or OPC, it is of much use in ordinary concrete construction. In the production of this type of cement in India, Iron (Fe2O3), Magnesium (MgO), Silica (SiO2), Alumina (AL2O3), and Sulphur trioxide (SO3) components are used.

Portland Pozolona Cement (PPC): As it prevents cracks, it is useful in the casting work of huge volumes of concrete. The rate of hydration heat is lower in this cement type. Fly ash, coal waste or burnt clay is used in the production of this category of cement. It can be availed at low cost in comparison to OPC.

Sulphate Resisting Portland Cement: This cement is beneficial in the areas where concrete has an exposure to seacoast or sea water or soil or ground water. Under any such instances, the concrete is vulnerable to sulphates attack in large amounts and can cause damage to the structure. Hence, by using this cement one can reduce the impact of damage to the structure. This cement has high demand in India.

Portland Blast Furnace slag cement (PBFSC): The rate of hydration heat is found lower in this cement type in comparison to PPC. It is most useful in massive construction projects, for example - dams

White cement: It is a kind of Ordinary Portland Cement. The content of iron oxide is maintained below 0.4% to secure whiteness. White cement is largely used to increase the aesthetic value of a construction. It is preferred for tiles and flooring works. This cement costs more than grey cement.

Important Books and Codes applicable in India for Architects and Civil Engineers

  • National Building Code 2005 - specifies minimum standard of design for buildings
  • Schedule of Rates 2007 by CPWD - Specifies the format of BOQ and Item Rate
      This book can be downloaded free of cost from the CPWD website from
      The book is listed under the 'Publications' tab on the navigation bar.
  • Analysis of Rates 2007 by CPWD - Specifies how the Item Rate has bee calculated
  • Delhi Master Plan 2021 - Species the use of land and per capita information
  • MCD Bye-Laws - Specifies construction restrictions for individual plots
  • Contracts - FIDIC and AIA (for international projects)