Method of constructing post tension RCC slab

In this construction video tutorial, you will learn how post tension RCC slabs are built up as well as how post tensioning is performed and benefits of post tensioning process.

POST TENSION SLAB: It refers to the slab that is tensioned as soon as the slab is developed. Reinforcement is arranged to avoid the compression.

In Post tension slab, cables or steel tendons are utilized to substitute the reinforcement. Post-tensioning offers a solution to get rid of the natural weakness of concrete in tension as well as optimize its strength in compression.

In concrete structures, this is obtained by arranging high-tensile steel tendons/cables in the element prior to start the casting. If the concrete attains the required strength, the tendons are pulled with special hydraulic jacks and retained in tension with specially designed anchorages which are attached at each end of the tendon.

It creates compression at the edge of the structural member that increases the strength of the concrete for resisting tension stresses.

If tendons are correctly curved to a specific profile, they will exert, other than compression at the perimeter, a useful ascendant set of forces (load balancing forces) that will neutralize applied loads, alleviating the structure from a portion of gravity effects.

In this type of concrete slab, cables are affixed in place of reinforcement. In Steel reinforcement the gapping among bars is 4inch to 6inch while in Post tension slab the gapping is in excess of 2m.

Go through the following video tutorial, to get more details on post tension slab.

Video Source: F&U-FORYOU

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Published By
Rajib Dey
www.constructioncost.co
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Details of tendering method in construction

Tendering: Tendering stands for the procedure of making an offer, bid or proposal, or revealing interest in providing respond to an invitation or request for tender. With tendering, interested contractors can send their bids to execute certain packages of construction work.

Organization will look for other businesses to make response to a specific requirement, like the supply of goods and services, and will opt for an offer or tender that fulfill their requirements and offers the best value for money.

Types of tendering:

a. Competitive tendering
Open - Selective

b. Negotiated tendering
Serial - Nominative

Open tender: Open tendering is the primary tendering procedures which are implemented by both the government and private sector. The client publishes the tender offer in the local newspaper as an advertisement. It provides the detail and essential information concerning the projected works as well as invite interested contractor to tender. In legal term such tender recognizes constitute invitation to treat, a simple request made by the employer for appropriate contractor to tender their bids or offers.

If the pre-requisite to tendering on the form of possession of the obligatory registration has been recognized in the tender notice, then the advertisement is conducted to only that specific class of the public with the stated qualifications. With the purpose of decreasing the number of enquirers, earnest money is paid in (for private project).

Unless the receipt of a bone fide tender is chosen then it will be refunded. The price is very crucial in taking the decision on which the tender or bid should be received. The benefits and drawbacks of open tender are described below:

a. It empowers any concerned contractor to submit tender. So, it provides scope for an unfamiliar contractor to bid for the work.
b. The tender list becomes lengthy because too many contractors submit their tender for one job.

c. It facilitates the tender list to be created neutrally. Client will acquire the bargain possible. No favor should be provided for choosing any contractor.
d. Wasteful application of source.
e. Make sure that there is good competition not obliged to accept any offers.
f. The interrogation can be made for public accountability may be questioned if the lowest offer is not accepted.
g. Conventional method of tendering, recognized to all segment of the engineering and construction industry.
h. The reputable and established contractor is not allowed unless they are compelled because of the shortage of water.

Selective tender: The objective of selective tendering is to deal with the constraints of the open tendering process. Under this method, a short list of contractor is made and they are invited to present tenders. The objective of the elective tendering is to make the quality of the received bids better, to make sure that contractors who have required experience and skill get the scope to present the required bids, owning to urgency work involved, for certain reasons of the employer, as for instance security reasons in government projects, Etc. and to make the tendering procedure more simplified and reduce the burden on the associated parties. Such list is made by the suggestions from the Client’s professional adviser having knowledge of the Contractors undertaking the work earlier or advertisement via the newspaper (pre-qualification).

To get more information, go through the following page basiccivilengineering.com

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Published By

Rajib Dey

www.constructioncost.co

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Vital factors to impact the design and construction of embankment dams

Numerous factors provide significant effect on the construction and design of embankment dam. Through the design phase, the designer should consider these factors to make the design better.

Given below, the detail information on these factors :-

a. Accessibility of materials for construction
b. Properties of embankment dam site
c. Shape and size of valley where the dam is developed
d. Atmosphere of the area
e. Diversion of river
f. Existing time for construction
g. Function of the reservoir
h. Feasible wave action
i. Earthquake activity in the area

Accessibility of Materials for Dam Construction: Generally, construction materials for embankment dams can be easily accessed and frequently available at or close to construction site at low cost. It will significantly impact the design of embankment dam.

If excavated material like earth excavated for spillway construction is utilized in the construction, the economy of construction is enhanced.

Embankment dam designed and constructed on the basis of existing construction material.

Type of material obtainable at project site Designed embankment dam on the basis of existing construction material.

a. Impervious soil material Consistent embankment dam
b. Rock and impenetrable material Rock fill dam
c. Previous and Impervious material Zoned earth dam,

Properties of Embankment Dam Site: Normally, embankment dams are built up on nearly all types of soil. The design is significantly impacted by the characteristics of soil upon which the dam is built up. One of the significant impact is managing the type of treatment applied for the foundation.

Besides, soil properties affect the dimension of the dam as for example if the soil contains low bearing strength, then it is essential to trim down slopes and employ superior cross section and freeboard.

These measures are essential to deal with deferential settlement of the embankment dam.

For more information, visit the following site aitech.ac.jp

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Published By
Rajib Dey
www.constructioncost.co
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The Basic Requirements of Formwork

Formwork is a concrete construction that is used as either short or permanent molds into which fresh concrete or similar kind of materials are gushed to make it harden. The different types of concrete formwork construction depend on the material and the kind of structural element. They are given various names as per the type of structural member construction like slab framework, beam framework, column framework etc. to use in beams and columns.

The harden process requires time and includes an expenditure up to 20 to 25% of the cost of the structure or more than that; the temporary design structures are made of economic expenditure.

While the removing process of the framework is known as stripping that can also be used later; the unusable are called panel forms and the non-useable are called stationary forms. The most commonly used material for formwork is Timber.

This article is a short knowledge for people about formwork, the different types of formwork and the basic needs to complete a formwork properly. Formwork comes in several types such as:

1. Traditional timber framework
2. Engineering Formwork System
3. Re-usable plastic formwork
4. Permanent Insulated Formwork systems
5. Stay-In-Place structural formwork systems
6. Flexible formwork

Requirements of Formwork: It is stated above that framework varies as per material and material is the main ingredient for every framework, but for any kind of chosen material the three common principles of quality, safety and economy should be the same. While the quality of material ensures safety and also considerably helps to achieve the economy; any kind of failure in framework can cause of the loss of life and tragic financial loss. To avoid the loss the following guidelines should be followed from start to framing materials and for the associated components:

1. Strength: The strength of material must be sufficient to strong the forces expected and this is the important for both the structural design and safety aspect.
2. Stiffness: the structural movement under load should be small and sure; these deformities and separations are the necessary part of the whole deviations in the formed concrete surface. While planning the formwork system, a designer must take decisions upon the total acceptable variations and the extend workmanship errors and structural deformity. The material stiffness and the workmanship accuracy must be stable to ensure the stability of the total deviations to keep the tolerances.
3. Impact Resistance: The forms are made to make sure that the damaged form that is useless does not make falling debris and to make sure this important safety quality, materials displaying ductile failure are far above than those fail in a hasty and brittle manner.
4. Durability: The framework must be durable either it will affect the economy and the achievement quality concrete product at every reuse of the formwork; formwork is always pre made and used out in the open. When the matter of re-uses came the thing is dependable on its reaction of materials and components with weather and the framing, components and formface materials should be strong in any environment. Material durability is important for both the achievement of good quality concrete surface finishes and safe formwork structures.
5. Weight: While the assembling process in formwork, both the members and components are shifted into position by hand that will be applicable after the complete framework which are heavy and need a crane to do the shifting work. So the framing members, formwork components and formface materials must be keep in size so that they must be carried and lifted by the worker or the crane etc.
6. Accuracy: Every construction process is dependable on a lot of money so the work of lifting and cutting of materials must be done within a minimum amount of money and consistency of size of materials, plywood sheets and framing members is very important.
7. Compatibility: The framework materials should be fitted with either the fluid concrete or the strong concrete and at the formface, the elements of the form materials must not react with the wet cement or concrete.
8. Insulation: Some materials react with the environment if it’s become extra hot or cold, so the protection for the materials is must; if the mix becomes frozen and the chemical bondage damages then the concrete has to be placed at low temperatures, heat the mixing water etc. The placing of the fluid concrete for all forms can cause some damage with the crushed rock aggregate and the proper steps has to be taken to stop it.




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Published By
Rajib Dey
www.constructioncost.co
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