Structural retrofitting in Bangladesh: column jacketing, micro-concrete and DEA

Since the RMG safety programmes, thousands of factory buildings in Bangladesh have been assessed and strengthened. Retrofitting is now a mainstream civil engineering activity — and an estimating challenge.

Assessment first

A Detailed Engineering Assessment (DEA) establishes the as-built structure: concrete strength (cores, rebound hammer), reinforcement (scanning, cover), foundation and loads. The structural engineer then designs the strengthening.

Common strengthening methods

• RC jacketing of columns and beams — new reinforcement cage, dowels into the existing member, and a jacket of micro-concrete or self-compacting concrete.
• Steel jacketing — angles and battens or plates bonded and bolted.
• FRP wrapping — carbon or glass fibre sheets bonded with epoxy, for confinement and flexural strength.
• Crack injection — low-viscosity epoxy injected through ports.
• Additional members — shear walls, braces, new footings.

Sequence of works for a jacketed column

1. Prop and relieve the load where the design requires it.
2. Surface preparation — remove plaster, chip the concrete surface, expose corners.
3. Drill and fix dowels with chemical anchors.
4. Fix the jacket reinforcement.
5. Apply the bonding agent.
6. Shutter and pour micro-concrete while the bonding coat is tacky.
7. Cure and finish.

Measuring it in a BOQ

In EstiMatrix, link the bonding-agent and curing measurements to surface preparation so the areas always match, and use the rebar take-off for the cages. The PWD Retrofitting SoR covers many of these items; EstiMatrix also includes master templates for column jacketing, epoxy anchors and dowels.

Quality on site

• Surface preparation decides bond — check roughness and cleanliness before the bonding agent.
• Use the specified micro-concrete; site-mixed substitutes rarely flow into thin jackets.
• Pull-out test a sample of anchors.
• Keep a curing log.

Get expert help

Retrofitting needs calibrated equipment, specialised chemicals and experienced crews. Prime Base Engineering provides assessment, design vetting and turnkey execution — request a consultation.