Methodology ( Mohd Alzaki )
Corrosion of Steel in Reinforced Concrete Structures .1
:Definition and Description
Reinforcement corrosion in concrete occurs when moisture, oxygen,
chlorides or even carbonation are present. The reaction causes rust to
form which expands in volume resulting in cracks and eventually spalling
the concrete encasing it. In reinforced concrete structures Corrosion in
comparison with other damage mechanisms is often the most prominent
.in its impact on durability
:Causes of the Problem
Chloride exposure (from de-icing salts, sea water, etc)
Carbonation
Improper mix design due to Penetration Depth cover options, weak
concrete, low workability, or voids
Concrete of low strength and control.
:Impact on Concrete
Excessive cracking and spalling of concrete cover
Reduction in cross-section of steel member (loss of load bearing
capacity)
Reduced performance and service life of structure
Increased cost shutdown, maintenance or repair work
:Materials and Tools (General Overview)
RC components for visual inspection & analysis
Standards (for instance ACI318)
Reinforcement layouts for diagrams and reference models
Graphs depicting rate of reinforcement corrosion against conditions
of exposure
Step-by-Step Procedure to Fix or Avoid the Issue:
Specify type of environmental exposure (marine, industrial, etc.)
Verify concrete cover thickness and quality of compaction.
Examine concrete permeability alongside water-cement ratio.
Evaluate possible protective measures (coating, inhibitors).
Connect results with appropriate codes and standards.
Placing, Finishing, and Curing of Concrete in Civil Engineering .2
Projects
:Definition and Description
This problem stems from improper control with freshly mixed concrete
from the pouring (placing), surface finishing, and curing stages within the
construction sequence. These activities when not well executed can cause
a host of issues ranging from surface peeling to strength degradation.
:Causes of the Problem
Inadequate execution or poor supervision at site
Postponed setting or excessive waiting after casting under high
temperature
Skinning over of bleed water in hot weather or overzealous finishing
at the wrong time
Inappropriately timed or inadequate curing of concrete in hot
weather
Lack of skilled labor or supervision on site
:Impact on Concrete
Surface blemishes (cracks, rough)
Cavitation and hollow spaces
Less resistance to damage and lower strength at an early age
Aesthetic and functional efficiency drop
:Materials and Tools (General Overview)
Compactors(vibrators)
Finishing tools
Curing equipment (water spray, plastic wrap, curing agents)
Diagrams of site layout or procedures for placement sequential
order
Step-by-Step Procedure to Fix or Avoid the Issue:
Results clarify the precise installation method for placement,
finishing, and curing.
Monitor local methods and note typical errors.
Examine the impact of temperature and time on every phase.
Identify the correct… tools and schedule for each action.
Arrange data according to ACI or on-site criteria.
Durability of Concrete .3
:Definition and Description
The concrete's durability is the ability to resist the effect of weather
exceptionally, the action of chemicals, friction, or any degradation while
retaining its desired engineering characteristics. Concrete should be built
to endure a long projected life with intelligent placement minimizing
.maintenance
:Causes of the Problem
Concrete mix fails due to excessive permeability, or poor mix
design.
Deterioration from aggressive environments such as chlorides and
sulfates or freeze-thaw cycles.
Misdirected attention to curing processes and quality control results
in failure.
Use of low quality materials, in incorrect proportions adds to failure.
Impact on Concrete:
Service life caveats
Structural performance degradation
Increased expenditure alongside maintenance and premature
repairs.
:Materials and Tools (General Overview)
Concrete mix designs featuring different w/c ratios.
Standards set for durability associated with ACI201 or BS EN 206.
Schematics demonstrating deterioration trends.
Exposure classification reference tables.
Step-by-Step Procedure to Fix or Avoid the Issue:
Assess impact of mix design and w/c ratio on durability.
Specify and classify environment exposure conditions.
Examine curing techniques and their effect on surface finish quality.
Conduct an analysis of SCM (fly ash, slag, etc).
Draft concise recommendations for achieving sustained long-term
performance.
