Details and Type of contracts

The contract is various types, for execution of civil engineering works. The contract are
» Lump Sum or Fixed Price Contract
» Measurement contract
» Turnkey Contract
» Design and BuildCost Plus Contracts
» Unit Price Contracts
» Time and Material ContractsItem rate contract
» Percentage rate contract
» Labour contract
» Piece-Work agreement
» Target Contract

1. Lump Sum or Fixed Price Contract :-

 The contractor agrees to perform the work specified and described in the contract for a fixed price. The price of a fixed contract can only be changed upon the execution of a change order, under which the owner and the contractor either

2. Measurement contract :-

A measurement contract might also be appropriate on projects where the design has not been completed in sufficient detail for bills of quantities to be produced.It should be possible to describe the works in sufficient detail to determine a programme and to  obtain rates from tenderers.  Generally tenderers rates will be based on drawings and approximate quantities.

3. Turnkey Contract :-

A turnkey contract is a business arrangement in which a project is delivered in a completed state. Rather than contracting with an owner to develop a project in stages. The developer is hired to finish the entire project without owner input.

4. Design and Build :-

Design and Build procurement works on the basis that the main contractor is responsible for undertaking both the design and construction work on a project, for an agreed lump-sum price. Design and build projects can vary depending on the extent of the contractor’s design responsibility and how much initial design is included in the employer’s requirements.

5. Cost Plus Contracts :-

The Cost Plus Contract is a type of a construction contract under which the owner agrees to pay the complete cost of the materials and labor needed to needed to build the project along with a fee for the contractor’s overhead and profit. This contract type is favored where the scope of work is highly uncertain or indeterminate and the type of labor, material, and equipment needed to build the project is also uncertain in nature.

6. Unit Price Contracts :-

Unit Price Contracts are based on anticipated quantities of items which are counted in the project in addition to their unit prices. The final price of the project depends upon the quantities required to carry out the work. Generally, these types of contracts are suitable only for construction and supplier projects which involve accurate identification of different types of items, but not their numbers, in the contract documents. These types of contracts are oftentimes used on excavation projects.

7. Time and Material Contracts :-

Time and Material Contracts are usually preferred if the project scope is not clear, or has not been defined. The owner and the contractor must establish an agreed hourly or daily rate, including additional expenses that could arise in the construction process. The costs must be classified as direct, indirect, mark-up, and overhead. Sometimes the owner might want to establish a cap or specific project duration to the contractor that must be met, in order to have the owner’s risk minimized.

8. Item rate contract :-

For this contract, contractors are required to quote rates for individual items of work on the basis of schedule of quantities furnished by the client’s department.

9. Percentage rate contract :-

In this form of contract, the client’s department draws up the schedule of items according to the description of items sanctioned in the estimate with quantities, rates, units and amounts shown therein.

10. Labour contract :-

This is a contract where the contractor quotes rates for the item work exclusive of the elements of materials which are supplied by the client’s Department.

11. Piece-Work agreement :-

This is that for which only a 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.

12.Target Contract :-

This is the type of contract where the contractor is paid on a cost-plus percentage work performed under this contract. 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 at prior agreed rates.

Types of Bricks and Details

Arrangement of bricks continuously in a row or horizontal way is known to be course. Depending on the arrangement of bricks there are some types of course.

Stretcher course – When the long and narrow faces of bricks are arranged in the direction of the length of wall, then that course is called as stretcher course. The narrow and lengthy faces of the bricks are seen from the front elevation of the course.

Header course – When the shorter faces of bricks are arranged in the direction of the length of wall, then that course is called as header course. The front elevation of header course resembles the shorter faces of the bricks.

Soldier course –When the long and thin faces of bricks are arranged in the direction of the length of wall, then that course is called as solider course. The front elevation of solider course resembles the long and thin faces of the bricks.

Sailor course – Same as soldier course but the difference is here, long and thick faces of bricks are visible from front elevation of this type course.

Rowlock course –When a 90 degree turn is applied to the header course front elevation, the rowlock course is achieved.

Shiner course – When a 90 degree turn is applied to the stretcher course front elevation, the shiner course is achieved.





Types of bricks

Types of bricks depending on their manufacturing method. The bricks are type Burnt bricks, Sundried bricks etc.

Burnt Bricks

By burning the brick mould with the mixture in the kiln, the burnt bricks are produced. These are the commonly used bricks in the construction field as they possess some good qualities or properties. These burnt bricks further classified into 4 different types namely, 1st class, 2nd class, 3rd class and 4th class.


Sun-dried bricks or unburnt bricks

Sun-dried or unburned/unburnt bricks are moulded/molded and let-to dry in sunlight instead of burning them in a kiln or clamp. These types of bricks are not enough strength, less fire & water resistance. Widely these types of bricks are not used in construction but sometimes this type used to construct cheap & temporary structures.

Types of Linear measurement & instruments and common errors

Linear measurement :-

 In civil engineering survey, the linear horizontal distance is to be measured to complete a survey. The measurement of this linear horizontal distance between two points on the earth surface is known as linear measurement. The measurement type can be divided as, direct measurement method, optical measurement method and electronic measurement method.

Direct measurement method :-

Direct measurement is obtaining the measurement directly which means measuring the length directly using simple equipment. The distance is actually measured during field work using a chain or a tape, arrows, ranging rods and offset rods, pegs, plumb-bob.

» Chain :-

The chain is composed of 100 or 150 pieces of galvanized mild steel wire called links, joined together with oval rings and handles at both ends. The length of chain is measured from one handle to other handle.

» Arrows or chain pins :-

They are also called as marking or chaining pins and are used to mark the end of chain during the process of chaining. They are made up of good quality hardened and tempered steel wire of 4mm in diameter. The arrows are made 400 mm in length. The one pointed part of an arrow is inserted into ground and the other is attached with ring.

» Ranging rods or Offset rods :-

Ranging rods or offset rods are round poles made up of wood or metal. These rods are used to range intermediate points of a survey. The only difference between ranging rods and poles is the length. Ranging rods and offset rods are commonly occurs in 3m length but the ranging poles are available up to 8m length.

» Pegs :-

The pegs are made up with wood and they used to mark the survey positions or terminals.

» Plumb-bob :-

A string suspended with a weight at the bottom will be both vertical and perpendicular to any level plane through which it passes.

» Tapes :-

Tapes are used for more accurate measurements.

Common instrumental errors in linear measurement :-

» Length other than standard :-

Tape manufacturers do not guarantee 100 ft steel tapes to be exactly 100.00 ft. An error due to the incorrect length occurs every time the tape is used.

» Temperature other than standard :-

Steel tapes are standardized at 68° F (20° C).
A temperature higher or lower will change the length of the tape. Temperature of the tape can be quite different from the air temperature measured.

» Tension :-

If tension is greater than standard the tape will stretch. If less than standard tension is applied the tape will be shorter than standard.

» Sag :-

A tape not supported along its entire length will sag. By applying correct tension the sag can be reduced.

» Poor alignment :-

This error occurs when one end of the tape is off-line or there is an obstruction in-line. The actual distance will be less than the measured dis. 

» Faulty marking :-

This error is random as the result of incorrect placement of chaining pins. Careful placement of chaining pins and then checking the measurement will reduce errors.

» Incorrect reading or interpolation :-

The error occurs when reading or noting the measurement clearly or in a hurry. Careful reading and using a small scale to determine the last figure will reduce errors.

»optical measurement method and electronic measurement method depending on the type of instrument that is used to measure the distance.

Timber Construction Good quality, useds

The woods that is available for construction is called as timber. the timber as a construction material is less demanded in civil engineering field.

» Uses of Timber in Construction:-

Timber is used as sleepers, coaches in railway construction.Timber used in making furniture.Timber used in the formwork construction.Timber used in making trusses, rafters, piles, arches , partition walls, poles, beams etc

Qualities of good timber in construction :-

1. Colour and Appearance of good timber: A good timber material must possess dark colour. Low strength of the timber can be understood from its light colour. For this the wood taken must be from the hard wood. This hard wood has to be free from the sap. Uniformity in colour has to be possessed by the wood.

In appearance, the wood must have a hard and shiny surface. Once the timber is planed, the surface must be smooth and bright in colour. Having a dull appearance shows all signs of defects in it.

2. Defects: The timber used for the construction has to be free from defects like blemishes, flaws, shakes, knots etc.

3. Timber Resistance and durability:The timber has to be resistant towards the action of fungi, insects, alkalies, physical agencies and mechanical agencies.

4. Weight of Timber: The weight and the density of timber have to be more. This will reflect a sound timber material.

5. Fibres in Timber: The timber is made of fibres in thousands. These fibres have to be straight and compact in nature. All the fibres within have to be firm and adhesive to each other.

6. Elasticity of Timber: Elasticity property of the timber material is essential for the construction of goods, trusses, shafts etc.

7. Mechanical Wear of Timber: The mechanical wear or abrasion resistance of the timber will help it to stay long when used in high traffic areas, as pavements or wooden floors.

8. Hardness of Timber: The resistance against penetration of any other material into the timber is gained by the hardness property. The chemicals that are present in the heart wood will impart hardness to the material. The density of the wood also defines the hardness of the timber material.

9. Shock Resistance of Timber: The timbers have to be resistant towards undesirable shocks. This is gained by shock resistance property.

10. Shape of Timber: All the preparation process of the timber must not bring any change in shape of the material. It must not undergo any change in shape even after it is subjected to structural use. Change in shape means either warping, expanding, splitting or swelling of the timber wood.

11. Timber with Good Finish and Polish:The timber is finally subjected to final finish and polish. The material must have the ability to take good polish when used in the application of window doors, furniture items. The surface of the timber must have the ability to receive the paint properly.

12. Odour and Sound: The freshly cut wood will have a sweet smell and an unpleasant smell shows the timber have started to decay. A ringing sound made by two pieces of wood will show that it is sound wood.

13. Strength of Timber: A good quality wood must possess strength to carry all types of loads. It must carry all the direct, shear and bending stress in order to behave as a sound beam, column, post, joist and a rafter.

14. Permeability of Timber: The permeability in case of timber, is the possibilities of penetration of water. Good quality timber must be impermeable in nature. The permeability is more along the direction of fibre orientation than on perpendicular direction.

15. Structure of Timber: The timber structure has to be uniform in nature. The timber cross sections consist of annular rings and medullary rays. The annular rings must be regular for good quality wood. This will have hard and compact medullary rays

16. Workability of Timber: Good timber must be able to cut easily, planed and smoothened easily. During the process of sawing, the teeth must not undergo clogging.

Technical specifications of a Civil Construction Project

Technical specifications are written requirements and instruction which is used with construction drawings to complete heavy civil construction projects. So, information provided in technical specifications and construction drawings are different.

If the information provided in technical specification conflicts with those provided in construction drawing, the provisions of the former will precede those of construction drawings.

Provisions of Technical Specifications of Civil Construction Projects

Technical specifications provide information about civil projects which is not provided in construction drawing. Information provided in technical specifications of heavy civil projects are as follows:

» Testing requirements for quality assurance and quality control.
» Steps for equipment and material placement
Detailed material requirements
» List of materials and equipments which are not provided or shown in construction drawings
» Construction sequence and restrictions
» Submittal and schedule requirements
» Measurement and payment provisions for all work items
» Coordination with other contractor at work
Permits achieved by owner
» Responsibilities
Safety issues
» Reference data for instance field and laboratory test data, records of existing site and facilities, stream flow records, and climatic data

Miscellaneous general requirements for example environmental abatement, temporary facilities, and waste disposal which cannot be shown in the drawings.

Types of Artificial stones

 Artificial stone, which is also called casted stone, is constructed from cement, sand , and natural aggregate such as crushed stone. it is possible to provide certain surface textures to artificial stones. Artificial stone or cast stone will be used for construction when cost effective and durable natural stone cannot be achieved.

Different types of artificial stone

Ransom stone

It is also called chemical stone which its compression strength is at least 32 MPa. Ransom stone is manufactured by blending silica soda with cement to provide fancy and ornamental flooring.

Concrete block

Concrete blocks are used for the construction of steps, window, sills, and piers. It is cased in the construction site.

Artificial marble

It is constructed from Portland gypsum cement and sand using either precast or cast in situ technique.

Bituminous stone

It is produced by impregnation of granite and diorite with refined tar. Functions of bituminous stone includes the provide wear, noise, and dust resistance stone surface.

Victoria stone

It is a granite piece which its surface is hardened by submerged the stone in silica soda for two months.

 Garlic stone

Garlic stone, which is employed as a surface drains and flag stones, is produced by mixing and casting Portland cement and iron slag.

Imperial stoner

The procedure used to produce imperial artificial stone includes careful washing of finely crushed granite, mixing granite with Portland cement, cast the mixture into a favored form, and finally steam cure the casted imperial stone for twenty-four hours.

There are various types of cement used in concrete construction.

There are various types of cement used in concrete construction.

1. Ordinary Portland Cement (OPC)

Ordinary Portland cement is the most widely used type of cement which is suitable for all general concrete construction. It is most widely produced and used type of cement around the world with annual global production of around 3.8 million cubic meters per year.  This cement is suitable for all type of concrete construction.

2. Portland Pozzolana Cement (PPC)

Portland pozzolana cement is prepared by grinding pozzolanic clinker with Portland cement. It is also produced by adding pozzolana with the addition of gypsum or calcium sulfate or by intimately and uniformly blending portland cement and fine pozzolana.

This cement has high resistance to various chemical attacks on concrete compared with ordinary portland cement and thus it is widely used. It is used in marine structures, sewage works, sewage works and for laying concrete under water such as bridges, piers, dams and mass concrete works etc.

3. Rapid Hardening Cement

Rapid hardening cement attains high strength in early days it is used in concrete where formworks are removed at an early stage and is similar to ordinary portland cement (OPC). This cement has increased lime content and contains higher c3s content and finer grinding which gives greater strength development than OPC at an early stage.

The strength of rapid hardening cement at the 3 days is similar to 7 days strength of OPC with the same water-cement ratio. Thus, advantage of this cement is that formwork can be removed earlier which increases the rate of construction and decreases cost of construction by saving formwork cost.

Rapid hardening cement is used in prefabricated concrete construction, road works, etc.

4. Quick setting cement

The difference between the quick setting cement and rapid hardening cement is that quick setting cement sets earlier while rate of gain of strength is similar to Ordinary Portland Cement, while rapid hardening cement gains strength quickly. Formworks in both cases can be removed earlier.

Quick setting cement is used where works is to be completed in very short period and for concreting in static or running water.

5. Low Heat Cement

Low heat cement is prepared by maintaining the percentage of tricalcium aluminate below 6% by increasing the proportion of C2S. This makes the concrete to produce low heat of hydration and thus is used in mass concrete construction like gravity dams, as the low heat of hydration prevents the cracking of concrete due to heat.

This cement has increased power against sulphates and is less reactive and initial setting time is greater than OPC.

6. Sulphates Resisting Cement

Sulfate resisting cement is used to reduce the risk of sulphate attack on concrete and thus is used in construction of foundations where soil has high sulphate content. This cement has reduced contents of C3A and C4AF.

Sulfate resisting cement is used in construction exposed to severe sulphate action by water and soil in places like canals linings, culverts, retaining walls, siphons etc.

7. Blast Furnace Slag Cement

Blast furnace slag cement is obtained by grinding the clinkers with about 60% slag and resembles more or less in properties of Portland cement. It can be used for works economic considerations is predominant.

8. High Alumina Cement

High alumina cement is obtained by melting mixture of bauxite and lime and grinding with the clinker. It is a rapid hardening cement with initial and final setting time of about 3.5 and 5 hours respectively.

The compressive strength of this cement is very high and more workable than ordinary portland cement and is used in works where concrete is subjected to high temperatures, frost, and acidic action.

9. White Cement

It is prepared from raw materials free from Iron oxide and is a type of ordinary portland cement which is white in color. It is costlier and is used for architectural purposes such as precast curtain wall and facing panels, terrazzo surface etc. and for interior and exterior decorative work like external renderings of buildings, facing slabs, floorings, ornamental concrete products, paths of gardens, swimming pools etc.

10. Colored cement

It is produced by mixing 5- 10% mineral pigments with ordinary cement. They are widely used for decorative works in floors.

11. Air Entraining Cement

Air entraining cement is produced by adding indigenous air entraining agents such as resins, glues, sodium salts of sulphates etc. during the grinding of clinker.

This type of cement is especially suited to improve the workability with smaller water cement ratio and to improve frost resistance of concrete.

12. Expansive Cement

Expansive cement expands slightly with time and does not shrink during and after the time of hardening . This  cement is mainly used for grouting anchor bolts and prestressed concrete ducts.

13. Hydrographic cement

Hydrographic cement is prepared by mixing water repelling chemicals and has high workability and strength. It has the property of repelling water and is unaffected during monsoon or rains. Hydrophobic cement is mainly used for the construction of water structures such dams, water tanks, spillways, water retaining structures etc.