Sketches/Maps of Concrete Cracks Observed in Visual Inspections

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Sketches or maps or patterns of different types of cracks commonly developed in concrete structures are crucial to determine the type and cause of cracks during visual inspection.

This would also reduce the time and effort needed to specify the reason for crack initiation. In this article, sketches of the common type of cracks observed in visual inspections are presented.

Sketches/Maps of Concrete Cracks Observed in Visual Inspections

1. Cracks Due to Earthquake

Fig. 1 shows cracks in both beams and columns due to seismic forces.

2. Cracks Due to Bending and Shear Forces

Fig. 2 shows cracks in a beam due to bending moment (vertical cracks at the middle of the beam) and inclined or diagonal cracks near beam supports due to shear forces. Fig. 3 also shows diagonal cracks.

3. Cracks due to Column Settlement

Fig. 4 shows cracks due to differential settlement of columns at the top of the column that has been settled and at the top side of the slab close to the column that has not suffered from settlement.

4. Cracks due to Ground Condition Changes

Two patterns of cracks are presented in Fig.5. Cracks due to low temperature are shown above (a), whereas crack maps due to dryness are presented below (b).

5. Cracks Due to Concrete Settling

The horizontal cracks shown in Fig. 5 is observed in visual inspection of concrete structures, and it is caused by concrete settling.

6. Cracks Due to Sinking of Timbering

Crack pattern shown in the figure below is caused by the sinking of timbering. So, improper formwork has led to such type of cracks in reinforced concrete element.

7. Cracks Due to Bowing of Formwork

Fig. 8 shows cracks along the span of formwork that have bowed or deflected excessively.

8. Map of Cracks Caused by Abnormal Set of Cement

Fig. 9 presents pattern of cracks that is developed due to uncommon set of cement.

9. Cracks Due to Insufficient Reinforcements

Fig. 10 shows sketches of cracks that have developed due to inadequate reinforcement ratio. The cracks developed along the span of the beam.

10. Cracks due to Atmospheric Conditions

Pattern of cracks developed in structural wall due to atmospheric condition variations such as high temperature or moisture.

11. Crack Pattern of Fire Effect

Fig. 12 shows maps of cracks in reinforced concrete beams and columns that have developed due to fire exposure.

12. Cracks Due to Freezing and Thawing Cycles

Sketches of cracks that developed due to freezing and thawing cycles are shown in Fig. 13.

13. Cracks Due to Aggregate Exposure

13. Cracks Due to Non-unifomirty of Admixture

The crack pattern shown in Fig. 14 is observed in visual inspection and found to be caused by non-uniformity of admixture in concrete.

14. Pop-out Due to Reactive Aggregate and High Humidity

The presence of reactive aggregate in concrete and high humidity have led to concrete pop-out as shown in Fig. 15.

15. Cracks Due to Steel Rusting

Pattern of cracks developed in reinforced concrete beams and columns shown in Fig. 16. Rusting of steel bars is common cause of structural deterioration which is caused by chloride ions and carbonation. Fig. 17 shows crack pattern of walls due to severe rusting of embedded steel bars.

16. Cracks Due to Concrete Sinking

Pattern of cracks presented in Fig. 18 is caused by concrete sinking. The cracks started and developed from area around steel bars.

17. Cracks Due to Loss of Workability

The crack pattern shown in Fig. 19 resulted from mixing concrete for too long or too long time of concrete transportation.

18. Cracks Due to Unsuitable Process at Construction Joint