BROAD CLASSIFICATION

Ai) MICRO CRACKSii) MACRO CRACKSBi) STRUCTURAL CRACKSii) NON-STRUCTURAL CRACKSCi) STABLE CRACKSii) UNSTABLE CRACKSDi) HARMFUL CRACKSii) HARMLESS CRACKS

ORIGIN OF CRACKS

CRACKS MIGHT DEVELOP DUE TO -

1.STRUCTURAL DEFICIENCY RESULTING FROM DESIGN DEFICIENCY OR CONSTRUCTION DEFICIENCY.

2.DETERIORATION OF CONCRETE OR CORROSION OF REBARS DUE TO POOR CONSTRUCTION OR INAPPROPRIATE SELECTION OF CONSTITUENT MATERIALS.

3.TEMPERATURE AND SHRINKAGE EFFECTS.

4.OVERLOADING OF MEMBERS

5. SETTLEMENT OF SUPPORTS.

6. NATURAL HAZARDS; ETC.

ORIGIN OF CRACKS (Contd)

CHARACTERSTICS

Occurs when there is flexural st. deficiency Occurs in maximum moment region Maximum width at bottom face Converges towards top Occurs either singly or in group

REPURCUSSIONS

Affects structural soundness Needs to be attended to as early as possible

CHARACTERSTICS

Occurs when there is flexural st. deficiency Occurs in maximum moment region Maximum width at top face Converges towards bottom Occurs either singly or in group

REPURCUSSIONS

Affects structural soundness Needs to be attended to as early as possible

CHARACTERSTICS

Occurs when there is shear st. deficiency Occurs in maximum shear region Maximum width at mid-depth Converges towards top/bottom Occurs either singly or in group

REPURCUSSIONS

Affects structural soundness Needs to be attended to as early as possible

CHARACTERSTICS

Occurs when there is torsional st. deficiency Uniform width throughout Occurs in the form of a spiral Occurs singly

REPURCUSSIONS

Affects structural soundness Needs to be attended to immediately

CHARACTERSTICS

Occurs when there is bond deficiency Occurs directly over internal rebars Uniform width Occurs at deficient locations

REPURCUSSIONS

Affects structural soundness Rebar corrosion triggered Needs to be attended to as early as possible

CHARACTERSTICS

Bulging of cross section significant Occurs when loaded beyond capacity Several cracks appear in bulged region

REPURCUSSIONS

Structurally dangerous situation Needs to be attended immediately

CHARACTERSTICS

Occurs in tension members when capacity is exceeded Uniform width throughout and parallel to each other Occurs over the whole length

REPURCUSSIONS

Affects structural soundness Needs to be attended to as early as possible

PLAN

DIRECTION OF CONCRETING

LIMITATION OF CRACK WIDTHSDEPENDING ON THE EXPOSURE CONDITIONS LIMITATIONS ON CRACK WIDTH ARE IMPOSED.

1. FOR MEMBERS IN WATER STORAGE UNITS, SEWAGE TREATMENT PLANTS, STRUCTURES IN CHEMICALLY HAZARDOUS ATMOSPHERE, ETC.CRACKS ARE NOT PERMITTED IN R.C. MEMBERS.

2. IN SEVERE ATMOSPHERES UPTO 0.1MM CRACK WIDTH PERMITTED.

3. IN MILD AND MODERATE ATMOSPHERE UPTO 0.2mm CRACK WIDTH PERMITTED.

Measuring Magnifier - Proceq

CRACKSCOPE - GERMANN INSTRUMENTS

DIGITAL CRACK GUAGE - ELE

LOMARO MICROSCOPE- ELE