INVESTIGATION INTO THE CAUSES, EFFECT AND PREVENTION OF CRACKS IN BUILDING

ABSTRACT
Investigation into the causes, effects and prevention of crack in building, cracks this is a kind of defects that occur into building structure which rendered building unsightly and reduces building stabilities. Cracks may be of structural failure or non-structural problem which may act slightly, moderate or several.

They are save or dangerous depending on the size and characteristics of each i.e. 0-3-1.00, 1-2, 2-5,5-15 and 15-25 (mm) respectively survey of building were made in some selected area in Ilorin west L.G.A Ilorin, were aerial photographs were taken, site investigation were made in some selected areas.

Cracks in building could be as a result of use of poor materials, inappropriate mix ratio, poor workmanship, lack of soil test, foundation settlement, poor supervision, environmental problems faulty construction, faulty design and overloading, non-structural crack are mostly due to internally induced stresses in building but may look unsightly or may create an impression of instability or faulty work in some situation due to penetration of moisture through them, non structural cracks may spoil the internal finishing which thus adding to the cost of maintenance or corrode the reinforcement thereby adversely affecting the stability of the structure in long run e.g vertical crack in a long compound wall due to shrinkage or thermal movement.

Crack may appreciably vary in width from thin hair crack barely visible to naked eye to gaping crack depending upon the crack width, a crack are classified.

Research shows that some of the problem of crack in Ilorin west here are due to lack of maintenance and negligence i.e allowing vegetative growth near structures which will be treating the structure, allowing unnecessary water to lodge at the base of structure.

All these problem could be control by adequate maintenance professional advise and involvement in all project, been it new construction or renovation and vegetation should be control not only for constructional problem but heath wise, security conscious and social befitting.

CHAPTER ONE
10 INTRODUCTION
Occurrence of various cracks patterns in the building during construction, and after completion when it is subjected to super imposed load or during the service life, is a common phenomena’s. A building component develops cracks whenever the stress in the component exceeds it’s strength. Stress in the building component could be caused by externally applied forces, such as dead, live, wind and seismic loads, foundation settlement e.t.c or it could be induced internally due to thermal movement, moisture changes elastic deformation, chemical reaction e.t.c
Cracks in building could be broadly classified into two, as structural and non-structural cracks.
Structural Cracks: These occur due to incorrect design, faulty construction or overloading and these may endanger the safety of the building eg extensive cracking of an RCC beam (rein force concrete course)
Non-Structural Cracks: These are mostly due to internally induced stresses in building but may look unsightly, or may create an impression of faulty work or may give a feeling of instability in some situation due to penetration of moisture through them, non-structural cracks may spoil the internal finishes thus adding to the cost of maintenance, or corrode the reinforcement, thereby adversely affecting the stability of the structure in long run e.g vertical crack in a long compound wall due to shrinkage or thermal movement.
Cracks may appreciably vary in width from thin hair crack barely visible to naked eye to gaping crack. Depending upon the crack width crack are classified as.
(a) Thin Crack — less than 1 mm in width
(b) Medium Crack — 1 to 2mm in width
(c) Wide Crack — more than 2mm in width
(d) Crazing — Occurrence of closely fine cracks at the surface of a material these is called crazing.
Cracks may be of uniform width through out or may be narrow at one end gradually widening at the other end.

Cracks may be straight, toothed, stepped, map pattern or random type and may be vertical, horizontal or diagonal.
Cracks may be only surface and extend to more than one layer of materials.

Cracks due to different causes have varying characteristics and by the careful observations of these characteristics, one can diagnose the causes of cracking for adopting the appropriate reduced measures.

Small magnitude causing tension and shear stresses can lead to cracking. Internal stress are induced in the building component on account of thermal movements, moisture change, elastic deformation, chemical reaction etc.
All these phenomenon causes dimensional changes in the building components, and whenever this movement is restraint due to interconnectivity of various member, resistance between the different layers of the components etc.

stresses are induced and whenever these stresses (tensile or shear) exceed the strength of material cracks occurs.
Depending upon the cause and certain physical properties of building materials, these cracks may be wide, but further apart or may be thin but more closely space.

As a general rule, thin cracks even though closely spaced and greater in number, are 1ess damaging to the structures and are not so objectionable from aesthetic to the structure and other consideration as fewer number of wider cracks.
 
2.0 STATEMENT OF THE PROBLEM
The statement of the problem can as well be the causes of crack in building. Which are as stated below
For the structural cracks
• Incorrect design
• Faulty construction
• Overloading
Cracking of an RCC beam which can lead to extensive cracking of RCC beam which may endanger the building safety.
Non-structural cracks involved
• Moisture change
• Thermal movement
• Elastic deformation
• Creep
• Chemical reaction
• Foundation movement and settlement of soil
• Growth of vegetation
Those element are mostly due to internally induced stresses in building materials and do not endanger safety of a building but may look unsightly, or may create an impression of faulty work or may give a feeling of instability in some situation due to penetration of moisture through them.

Non-structural cracks may spoil the internal finishes thus adding to the cost of maintenance, or corrode the reinforcement thereby adversely affecting the stability of the structure in the long run e.g vertical crack in a long compound wall due to shrinkage or thermal movement.
AIM The aim of this project research is to investigate into the causes, effects and prevention of cracks in building.
OBJECTIVES OF THE STUDY
1. To determine the various type of cracks that occur in building.
2. To know the behaviors and effect of each types of cracks in building.
3. To be able to prevent each types of cracks in building.
4. To be able to know forms of cracks that occurs in building.
5. To create a solution or remedies to an existing cracks in building.
6. To know the behaviors of some constructional materials which could lead to crack in building and suggestion of preventive measure.
7. To know the preparation measure to put in place in construction site so as to prevent the effect of moisture changes, thermal movement, chemical reaction, foundation movement, settlement of soil and growth of vegetation around the site.
JUSTIFICATION
This project will assist building industry in solving the problems of cracks in building both structurally and non-structurally and know how to classified and control each crack into their respective forms and types. i.e structural and non structural, thin, medium, wide or crazing.
 
SCOPE OF THE STUDY
This project is base on crack in building and due to time constraints, this study is limited to causes, effect and prevention of crack in building so as to prevent the occurrence of cracks and solution to the existing difference, types, and forms of cracks in building.
METHODOLOGY
So as to investigate into the causes. effect, and preventions of cracks in building the proposed methodology to be use in this research are a follows.
1. Reviewing of literatures, and other related articles materials in line with this research.
2. Pictures and photograph of section where cracks occur in building will be taken for examination and correction.
DEFINITION OF TERMS AND FULL MEANINGS
1. RCC-reinforce concrete course