Role Of Chemicals In Segmental Bridge Construction

 

A  bridge is a structure built across an obstacle such as a body of water, valley, or road, for the purpose of providing passage over the obstacle. Designs of bridges depending on the function of the bridge, length of the bridge, span of the bridge, the nature of the terrain, and the material used to make it.

Construction Methods For Bridge

Cast-In-Situ Method

    This method is preferred for Short Bridges. Time consuming is large in cast-in-situ construction as it involves following steps.

Erection on ground supported staging

Casting of concrete

Dismantling of staging

Precast Segmental Method

This method is used for long bridges. It is economical when there is large no of span. This method involves the following steps.

Casting of Precast segments in casting yard

Transporting the precast segments at the site

Erection of the precast segment using launcher or crane

External Prestressing

Grouting

A Segmental Bridge is a bridge built in short sections (called segments), that is one piece at a time. And then segments are erected to make the bridge. The bridge is either cast-in-place or precast.

 

Advantage Of Segmental Bridge Construction

Very economical for long spans

Prefabricated segments provide better quality control

The structure can be fully loaded immediately after being prestressed

The pre-stressed cables can always be inspected and replaced

Low weight due to thin bridge sections

Low maintenance costs

Speed of construction, time taken is less

Because of the above-mentioned reasons segmental bridges are now increasing gradually in India. In most urban habitats, it becomes inevitable to go for long elevated viaducts, as effective means of transport. These elevated viaducts easily clear the congested roads and other inhabitations, at ground level leaving them unhindered. Needless to mention that they create additional movement area, without jeopardizing the existing ground level network

It is understood and agreed by masses that Metro Rail is the best means of transporting large set of commuters, especially in mega cities. Basic attributes of planning were speed of construction for a larger size project and yet economical.

Similarly, many long-elevated viaducts are in various phases of construction

Construction Of Segmental Bridges

The following steps are used for the construction of Segmental bridges.

Casting Of Segments

Two methods are used for casting of segments

Short Line Method:  In this rate of segment production is slow. Three or four segments cast at a time

Long Line Method: In this rate of segment production is fast. Segments equal to one span cast at a time. After casting the segments are stored at staking yard and curing of segments will be done

Transfer The Segment At Erection Site

After casting or curing of segments are transferred at erection site with the help of traveller or crane

Erection of the Segments

The precast segments are erected on the sites by following erection methods

Balanced Cantilever erection

Progressive Placement erection

Span by Span erection

Incremental Launching erection

Epoxy Gluing

In between the two segments epoxy gluing is used to prevent the leakage of grout during grouting

 

External Prestressing

Used for giving the final strength to bridge.

Pre-tension method

Post-tension method

Grouting

The main purpose of grouting is to protect the all strands against corrosion and develop the bond between prestressing steel and surrounding concrete

Two methods used for casting of segments

Short Line Method:  In this rate of segment production is slow. Three or four segments cast at a time.

Long Line Method: In this rate of segment production is fast. Segments equal to one span cast at a time. After casting the segments are stored at staking yard and curing of segments will be done

Precast segmental box girder has been found to be the best structural solution, the world over. This way the pre-casting, transportation, erections and launching lead to an overall reduction of construction time.

For epoxy based segmental glue Fairmate has the product named FAIRBOND CS (W), which is working between the temperature range of 10°C to 35°C and FAIRBOND CS(S), which is working between the temperature range of 25°C to 45°C. Those products are being used extensively in various prestigious projects of India. This product conforms to FIP, AASHTO & ASTM.

Besides the Epoxy Glue, Fairmate has all ranges of Admixtures, Curing Compounds, Grouts, Sealants as well as Repair Mortars for the bridges.

For more information, visit: www.fairmate.com