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.

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.

Factors Affects Air Content of Concrete

Concrete air entrainment is not an easy process since it is influence by several factors. These factors shall be properly investigated to be able to obtain designated air entrainment.

Factors Affecting Air Content of Concrete

» Water content
» Fine aggregates grading
» Coarse aggregates
» Temperature of concrete
» Mixing action of concrete
» Use of admixtures other than air entrained admixture
» Cement content of concrete
» Fly ash content
» Vibration or compaction of concrete

1. Water Content :-

Increase of water content in the mixture will lead to increase concrete air content and vice versa. This is because the increase of water content would increase fluid mixture into which air bubbles could be integrated easily through mixing operation. Hard water such as well or quarry water, which contain minerals, would reduce air content if they are used to dilute air entraining admixture.

2.  Fine Aggregate Grading :-

Air entrainment will be carried out easily as the percentage of fine aggregate is increased. Fine aggregate sizes ranges from sieve No. 30 to sieve No. 100 will create small voids that can contain air bubbles. However, other fine aggregate sizes will require greater quantity of air entraining admixture to reach the same air content.

3. Coarse Aggregate :-

Presence of dust on coarse aggregate surface decreases air content. Crushed aggregate would entrain lesser air compare with gravel aggregate.

4. Temperature :-

For constant amount of air entraining admixture, the increase of temperature will lead to decline concrete air content. So, if temperature varies considerably during mixture production, it would be required to adjust air entraining admixture to achieve designated air content. Temperature reduction from 21C to 5C will increase air content by 40% whereas increase of temperature from 21C to 38C will decline air content by 25%.

5. Mixing Action :-

Air content increase by mixing for up to 15 minutes and mixing beyond this time will decrease air content. Entrained air will vary with type, physical condition, speed of the mixer and quantity of concrete that is being mixed. Seriously worn mixer will increase difficulty of air entrainment operation. Similarly, mixer with significant amount of hardened concrete buildup on mixer blades or in a drum increase air entrainment operation.

6.  Admixtures other than Air Entrained Admixture on :-

There are number of admixtures that have air entraining capacity for example retarding admixture and water reducing admixture. So, smaller quantity of air entraining admixture will be needed when these admixtures are also provided in the mixture.

7. Cement :-

Air content of concrete reduces with the increase of cement fineness. For the same air content, concrete produced using Type I cement need considerably lesser quantity of air entrainment admixture compare with concrete made with Type III cement.

8. Fly Ash :-

Air content reduces as the fineness or surface area of fly as increases. Increase of fly ash per unit concrete reduces air content of concrete and increase in fly ash carbon content reduces concrete air content.

9. Vibration :-

Vibration reduces concrete air content. For example, half of air content will be lost if vibration is applied for more than three minutes.

Used of Drip Irrigation in civil engineering

                                                               

                                             Drip Irrigation

  INTRODUCTION

•  Also known as trickle irrigation or micro irrigation
• To apply sufficient moisture to the root of the crop - prevent water stress
•  A major difference between drip system and most other systems is that the balance between crop evapotranspiration and applied water

   What is Drip Irrigation?

•  In this system, water is delivered directly to the soil near the roots of the planet Through a special outlet device called an emitter or dripper
•  Water is supply drip by drip at very slow rate 2-10 ltr/hr
•  The water applied near the root zone spread laterally as well as vertically due to capillary action in the soil
  

   NEED OF DRIP IRRIGATION

•  To use water efficiently
•  No water to runoff or evaporation.
• It reduces water contact with crop leaves, stems, and fruits.
• Agricultural chemicals can be applied more efficiently

 DRIP IRRIGATION IS USEFUL FOR CROPS....

• FRUIT CROPS

          Banana, pomegranate, Grapes, Citrus, pineapple, watermelon,
          mango etc.

• VEGETABLE CROPS

         Cabbage, Cauliflower, Potato, Chillis, Radish, Brinjal, Capsicum,
         Bhindi, Beans, Baby corn, Carrots, Cucumber, Ashgourd,
         Gherkins, etc.

• COMMERCIAL CROP

          Cotton...


  MAIN COMPONENTS OF DRIP.       IRRIGATION

•  Water Source
•  Pumping System
•  Distribution System
•  Drip tape ( drip tube )
•  Injectors
•  Filtration System

                       Drip Irrigation

       Water Source

• Common water source for drip irrigation are surface water, ground water and potable water.
•  Use the water source that will provide the largest amount of water of greatest quality and lowest cost.

      PUMPING SYSTEM

•  The role of the pumping system is to move water from the water source to the field through the distribution system.
•  Pumping system may be classified as electric powered system, gas/diesel powered system and gravity system.

       DISTRIBUTION SYSTEM

•  The role of the distribution system is to convey the water from the source to the field.
• Distribution system may be above ground or underground.
•  Pipes are most commonly made of PVC or polyethylene plastics.
• Aluminium pipes are also available, but are more difficult to customize, cut, and repair.

     Drip tape

•  The drip irrigation system delivers water to each plant through a thin polyethylene tape ( or tube ) with regularly spaced small holes .
•  In the field, drip irrigation tape should be installed with emitters upward ( looking up ) to prevent clogging

     INJECTORS

•  Injectors allow the introduction of fertilizer, chemicals and maintenance products into the irrigation system.
•  The most common injectors used with small drip irrigation systems are the Venturi (or Mazzei) injector and the Dosatron.
•  Because Venturi injectors involve no moving parts and are less expensive, they are commonly used on small farms.

    Filtration system

•  The filtration system removes "large" solid particles in suspension in the water.
•  Usage of type of filter is based on the type of particles in the water.
• Rapid clogging may occur when no filter is used.
• A drip irrigation system should never be operated without a filter even if the filter requires clogged drip tape emitters, often resulting in poor uniformity and sometimes in crop loss.

     Advantages Over Surface Irrigation

• Maximum use of available water.
•  No water being available to weeds.
•  Maximum crop yield
•  High efficiency in the use of fertilizers.
•  Low labour and relatively low operation cost.
•  No soil erosion.
•  No runoff of fertilizers into ground water.
•  Less evaporation losses of water as compared to surface irrigation.
•  Improves seed germination.

       Application

• Drip irrigation is used by farms, commercial green houses and residential green houses.
•  For cultivation in roof gardens .
•  In shopping malls and embankments.
• In steep slopes

                                                                            Conclusion

• Drip irrigation is a latest sub - surface method of irrigation water with higher water demands in arid region .
• It may not be applicable to all farms .
• Drip irrigation increase yields .