Prayer

Mission Impossible

ISSUE #32 - Causes of Distress and Deterioration of Concrete

Once the evaluation phase has been completed for a structure, the next step is to establish the cause or causes for the damage that has been detected. Since many of the symptoms may be caused by more than one mechanism acting upon the concrete, it is necessary to have an understanding of the basic underlying causes of damage and deterioration. This presents information on the common causes of problems in concrete. Deterioration of concrete is an extremely complex subject. It would be simplistic to suggest that it will be possible to identify a specific, single cause of deterioration for every symptom detected during an evaluation of a structure. In most cases, the damage detected will be the result of more than one mechanism. For example, corrosion of reinforcing steel may open cracks that allow moisture greater access to the interior of the concrete. This moisture could lead to additional damage by freezing and thawing. In spite of the complexity of several causes working simultaneously, given a basic understanding of the various damage causing mechanisms, it should be possible, in most cases, to determine the primary cause or causes of the damage seen on a particular structure and to make intelligent choices concerning selection of repair materials and methods.

Causes of Distress and Deterioration Accidental Loadings
Chemical Reactions
Acid attack
Aggressive-water attack
Alkali-carbonate rock reaction
Alkali-silica reaction
Miscellaneous chemical attack
Sulfate attack
Construction Errors
Corrosion of Embedded Metals
Design Errors
Inadequate structural design
Poor design details
Erosion
Abrasion
Cavitations
Freezing and Thawing
Settlement and Movement
Shrinkage
Plastic
Drying
Temperature Changes
Internally generated
Externally generated
Fire
weathering

a. Accidental loadings.

(1) Mechanism. Accidental loadings may be characterized as short-duration, one-time events such as the impact of a barge against a lock wall or an earthquake. These loadings can generate stresses higher than the strength of the concrete, resulting in localized or general failure. Determination of whether accidental loading caused damage to the concrete will require knowledge of the events preceding discovery of the damage. Usually, damage caused by accidental loading will be easy to diagnose.
(2) Symptoms. Visual examination will usually show spalling or cracking of concrete which has been subjected to accidental loadings. Laboratory analysis is generally not necessary.
(3) Prevention. Accidental loadings by their very nature cannot be prevented. Minimizing the effects of some occurrences by following proper design procedures (an example is the design for earthquakes) or by proper attention to detailing (wall armor in areas of likely impact) will reduce the impacts of accidental loadings.

Engineering and Design
EVALUATION AND REPAIR OF
CONCRETE STRUCTURES Department of the Army U.S. Army Corps of Engineers Washington , DC 20314-1000

A Smile

A Smile costs nothing, but gives much

It enriches those who receive, without making poorer those who give

It takes but a moment, but the memory of it sometimes lasts forever

None is so rich or mighty that he can get along without it,

and none is so poor, but that he can be made rich by it

A Smile creates happiness in the home, fosters good will in business,

and is the countersign of friendship

It brings rest to the weary, cheer to the discouraged,

sunshine to the sad,

and it is nature's best antidote for trouble.

Yet it cannot be bought, begged, borrowed, or stolen,

for it is something that is of no value to anyone, until

it is given away

Some people are too tired to give you a smile;

Give them one of yours, as none needs a smile so

much as he who has no more to give.

Grace

Grace is of music…and the wind, invisible to my eye.
Grace is of my heart and soul, my guardian, first and last friend.
~Celebrator of my spirit~

Grace is hard to understand when I demand to touch and see.
It is the answer in between…the lines…
Intuition opens the door to readiness ~
sometimes doesn’t a special coincidence…
…happen at just the right time?

When I am utterly exhausted
Grace keeps me in the game.

We say that we don’t deserve grace, or need any special favors.
Why is it so hard for us to accept a gift we didn’t “earn”?
That is EXACTLY WHY we are given Grace.
Because we believe that we aren’t “good”…enough.

Grace is my Higher Power’s visibly invisible proof…
…of love, protection, and knowledge…
…that we are loved by God.

Mt Matutom Mt Apo from Kapatagan