�PROJECT PRESENTATION ON�CAUSES AND PREVENTION OF CRACKS IN BUILDINGS�BY GROUP OF STUDENTS OF III SEMESTER DSE �2020-21��

By Civilthings.com

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CONTENTS

• Introduction
• Causes of cracks
• Detection of cracks
• Conclusion
• References

INTRODUCTION

• A crack is a complete or incomplete separation of concrete into two or more parts, produced by breaking or fracturing o
• An engineer should have a sound knowledge of all the facts of concrete technology i.e. of the behavior of construction material, construction techniques, and types of crack likely to occur, their causes and respective remedial measure
• Treatment of cracks involves detection, diagnosis and remedy

TYPES OF CRACKS

• Structural cracks -Arise due to various reasons such as incorrect design, overloading of the structural components, overloading of the soil on which the building is constructed or other similar factors
• Non structural cracks -Arise due to internal forces developed in the buildings on account of change in the size of building components, due to moisture variation, temperature variations, the effect of gases, liquid and solids on the building components.

INVESTIGATION RELATING TO CRACKS

The following information helps in diagnosing the cracks:

1. Whether the crack is old or new.
2. Pattern of the cracks.
3. Soil condition, type of foundation used, and movement of ground if any.
4. Observations on the similar structures in the same locality.
5. Climatic condition during which the structure has been constructed

CAUSES FOR THE OCCURANCE OF CRACKS

• Structural deficiency resulting from design deficiency or construction deficiency and overloading.
• Temperature and shrinkage effects. o Cracks due to faulty workmanship and poor construction practice.
• Cracks due to settlement.

CRACKS DUE TO STRUCTURAL DEFICIENCY

-Due to design deficiency o Cracks occur due to shear, flexural and torsional steel deficiency. o Improper anchorage.

o Cracks due to overloading of members.

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• Figure: Shows a long crack in new wallboard with a width of about an inch at the corner of the door frame

PREVENTIVE MEASURES:

• Adequate insulating or terracing treatment over roof slab and by introducing joint between the slab and the supporting wall.
• Painting top of roof with reflective finish such as white wash can also minimize cracks.
• Chances of cracking due to temperature variation can be minimized by introducing expansion, contraction joints at appropriate locations.

CRACKS DUE TO FAULTY WORKMAN SHIP AND POOR CONSTRUCTION PRACTICE

Every building process includes a sequence of necessary step-by-step operation-from conceptual plan to finished structure Improper column form placement. Causes:

o Improper bar detailing o Premature removal of forms

o Cold joints

o Segregation

o Plastic shrinkage cracking

o Improper reinforcing steel placement

PREVENTIVE MEASURES

• By providing proper water cement ratio.
• Proper curing.
• Proper support for forms.
• Following proper design codes and recommendations

CRACK DUE TO SETTLEMENT

o Uneven settlement can be a major structural problem in small residential building

o Loss of moisture o Soil consolidation under footing

o Water table level o Occurs early in life of building

INJECTION TECHNIQUE

1. Injections that are used to restore the structural stability of the structures.
2. Injections that are used to protect the reinforcement to avoid the moisture and air entering the concrete thereby lower the rate of corrosion.
3. The injections which are used to stop the water from entering the structure.

CONCLUSION

As for as possible cracks should not develop in building and care should be taken that for important and multistoried buildings ,design & execution of building , cracks should not develop in any circumstances as cracks affects aesthetics of building & cracks may cause leaking problems in building.

REFERENCES

• Kishor Kunal : “Study on control of cracks in a Structure 2through Visual Identification & Inspection” IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 11, Issue 5 Ver. VI (Sep-Oct. 2014
• Rajveer Singh Narwaria : “ Development of cracks in concrete, preventive measures and treatment methods” : International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 03 Issue: 09 | Sep -2016
• Jailakshmi G Karri et al “Prevention and repair of cracks in building” International Journal of Research In Science & Engineering Volume: 3 Issue: 2 March-April 2017
• M.A. Jayaram “ Decision Support System for Detecting, Diagnosing and Suggesting Remedial Measures for Building Cracks” International Journal of Computer Applications (0975 – 8887) Volume 137 – No.6, March 2016

THANK YOU