TYPES OF CRACKS AND THE ORIGIN OF CRACKS AT DIFFERENT AGES

The appearance of cracks often raises many questions. Cracks can appear in structures at an early stage or over time and it must be recognized that certain types of cracks are unavoidable in the home.

 

Cracks can be large or small, structurally or non-structurally, or indifferent shapes, different widths, and different shapes.

 

All can be a nuisance either by damaging the structure in appearance or bypassing air pollutants and moisture into the body of the concrete.

 

TYPES OF CRACKS AND THE ORIGIN OF CRACKS AT DIFFERENT AGES:

Since cracks are natural in concrete, what really matters is the type of structure and the nature of the cracks.

 

The following table generally indicates the types of cracks:

 

COMMON CLASSIFICATION OF CRACK
CAUSES	NATURE	DIRECTION	SHAPE	PATTERN/DESIGN	WIDTH
Separation (RCC & masonry)	Structural	Vertical	Straight	Uniform throughout	Thin
Corrosion	Non-structural	Horizontal	Toothed	Narrow at one end & gradually widening at the other	Medium
Absence of lintel/sill bands	-	Diagonal	Stepped	-	Wide
Poor workmanship	-	-	Map pattern	-	Crazing
Poor quality of material	-	-	Random	-
Thermal expansion or contraction	-	-	-	-	-
Design failure	-	-	-	-	-
Moisture change	-	-	-	-	-
Overloading	-	-	-	-	-
Settlement of foundation n	-	-	-	-	-

 

Plastic Shrinkage Cracks

·       This type of cracks appear appear within the first minutes to hours after the concrete is made.

·       Plastic shrinkage cracking occurs when new concrete is subjected to a very rapid loss of moisture. It is caused by a mix of factors such as air and concrete temperatures, relative humidity, and air velocity at the concrete surface. These factors can cause excessive evaporation in hot or cold climates.

Plastic Settlement Cracks

·       Plastic Settlement Cracks appear in first few minutes or hours after concreting.

·       This type of cracks appear in cement concrete just placed / placed in a reinforced structure, sometimes occurring on the surface even before the concrete is set, when there is a relatively large amount of bleed and some types of barriers settling by the solids.

Cracks due to Corrosion

·       Corrosive cracks usually, appear after a year or several years.

·       Corrosion cracks appear in the reinforcement line and expand over time.

·       It is mainly manifested by discolouration of paint or rust stains.

Cracks due to Loads

·       It occurs After the loads are imposed for the first time

Cracks due to Dead Weights

·       It occurs After the formwork supports are removed.

·       This type of crack will appear if there is insufficient size or reinforcement bars section that cannot carry own dead weight.

Cracks due to chemical changes in Hardened Concrete

Chemical reaction (sulfate) or internal (ASR) depending on the chemical attack from the outside after one or several years.