Defects in brick masonry

2. MAIN OBJECTIVES
• Defects during manufacturing process
 Defects in size
 Defects in shape
 Defects in raw materials
• Defects in appearance
• Other defects
• Defects in constituents of bricks
• Defects during construction process
• Defects in post-construction process
• General defects in brick masonry
• Environmental issues and effects
• Remedies

3. DEFECTS DURING MANUFACTURING PROCESS
DEFECTS IN SIZE
Oversize in all 3 dimensions
• The brick may be underfired.
• The presence of too much sand will decrease the
amount of drying.
• The brick will be lighter than normal, and there will
be a dull "ring "when knocked with another brick
instead of a metallic sound.

4. Oversize in width and length
• The brick may have been squashed while still
wet.
• This may have happened when the brick was set
down on the ground or drying rack after being
molded or if a slop molded brick was pressed to
flatten out a distortion.

5. Oversize in thickness
• This is a common fault with wire cut bricks.
• In the process of wire cutting, the block of clay is forced
through a row of wires.
• The force on the wire may cause movement that
changes the dimension of the opening which the clay
passes through.

6. Undersize in all dimensions
• The brick may have been made with an undersized
mod, but another cause could be a problem of too high
of clay content in the batch, or using too much water
during the mixing stage.
• Another cause could be over firing, common to bricks
around the tunnels in a field kiln.

7. DEFECTS IN SHAPE
Slumping
• The clay mix was too wet and
the brick slumped under its
own weight.
Rounded corners
• When molding, the worker may
not have pressed enough clay
into the mold, or it may have
broken between drying in firing.

8. Raised corner
• The brick may have stuck
to the mold when being
removed from the mold.
Lip on bed face
• The excess clay may not
have been removed with
the bow cutter and a small
"flashing" is left around
borders the top edge.

9. Flashing on top face
Distorted or contaminated
under-surface
• The drying surface may be
uneven or dirty. This happens
more often with slop molding,
because the wetter mixture can
pick up more particles.

10. Stacking marks
• If bricks are moved too soon
to drying stacks from
individual drying, they may
distort.
• Also, fingerprints or other
marks may get on the surface.
Banana shapes
• If the bricks are not turned over
during the initial drying stage
before the top gets hard, this
defect is more likely to occur.

11. Multiple distortions
• Some bricks may inevitably become distorted in
multiple ways. This may have happened in the forming
stage, and the brick should have been rejected before
being fired.
• Bricks may also distort if over burnt at the base of the
clamp.

12. DEFECTS IN RAW
MATERIAL
Underfiring
• The clay will be a lighter color,
and when knocked together, the
bricks will not have the expected
metallic sound, but rather a dull
clunk.
Straight cracks at right angles
from one of the long surfaces
• These cracks form if the drying
process is too fast, and the brick
may break even if fired correctly.

13. Multiple surface cracks in
random directions
• Differential drying can
cause shrinkage, and lumps
of drier material will shrink
differently than the rest of
the brick.
Lamination crack
• This defect may occur in the
sand-molded process if a
piece of clay covered with
sand is mixed into another
piece.
• The film of sand may separate
the two pieces of clay if
stresses occur during drying
or firing.

14. Extrusion Laminations
• The defect occurs where the turning effect of the
equipment pushes the clay out of the machine:
the center of the brick is turning faster than the
outside clay.
• These defects are weak spots because they can
be harmed by frost damage or spalling.

15. DEFECTS IN APPEARANCE
Spalling
• The process of water
heating and exploding
inside the brick is called
spalling.
Dog-eared corners
• This happens in extruded
bricks when the brick
leaves the machine.

16. Ragged arises
• If the long face of the
brick from a wire cut is
deformed, the wires may
not be tightened
properly.
Drag marks
• These can appear from residue on the wire, bow
cutter or smoothing stick.

17. Barmarks
• Barmarks are the result of the firing process where kiln
gases do not reach the entire surface of a brick.

18. OTHER DEFECTS
SHRINKAGE ON DRYING
• creates cracks in brick masonry joints.
• can be prevented by using good quality of brick and
mortar and protecting from moisture.
OVERBURNING OF BRICKS
• If the bricks over burnt, a soft molten mass is produced
and the bricks lose their shape.
UNDERBURNING OF BRICKS
• result in higher degree of water absorption and less
compressive strength.

19. BLACK CORE
• This results because of improper burning.
SPOTS
• Iron sulphide, if present in the brick clay results in
dark surface spots on the brick surface.
BLOATING
• Cause due to the presence of excess carbonaceous
matter and sulphur in brick clay.
CHUFFS
• The deformation of the shape of bricks caused by the
rain water falling on hot bricks.
POROSITY
• Having pores inside the brick.

20.  Excess alumina
-raw bricks will shrink and warp.
 Excess lime
-bricks will melt and the shape will not uniform.
 Excess oxide of iron
-bricks get dark blue blackish color.
 Excess Manganese
-since it decreases the shrinkage, although shrink
leads to decay bricks.
DEFECTS IN CONSTITUENT OF BRICKS

21. • Thermal Expansion and contraction
• Mortar Shrinkage
• Leveling
• Erratic supplies = Erratic delivery
(unfixed destination for supply and delivery)
• Waste
• Rework
• Slow delivery
• Inconsistent quality
• Color deterioration- due to frost damage
• Needs heavy foundation- to avoid cracking
DEFECTS DURING CONSTRUCTION

22. • BRICK CONSTRUCTIONS CAN’T TAKE PLACE IN
SEVERE WEATHER
-This is because, it’s a wet form of construction and needs to
dry adequately. If it freezes, certain parts of the construction
could expand and need replacing.
-This is why in some parts of the world where the climate is
very cold or moist, you’ll notice more timber construction
than brick.
• THE PROGRESS AND THE PROGRAMME CAN BE
AFFECTED BY ADVERSE (ACTION AGAINST) WEATHER
CONDITIONS.
• MATERIALS NEED TO BE STORED ON SITE AND
PROTECTED FROM THE WEATHER BEFORE THEY ARE
INCORPORATED INTO THE BUILDING STRUCTURE.
• LABOUR INTENSIVE.

23. o SULPHATE ATTACK
 This reaction causes increase in the volume of mortar and
consequently leads to cracks, chipping and spalling of brickwork.
 Commonly found in; Exposed boundary wall
Parapet wall
Manhole and retaining walls
 Can be prevented by adopting suitable construction detail and good
quality materials that prohibits entry of moisture into the body of brick
work.
o CRYSTALLIZATION OF SALT FROM BRICKS
(EFFLORESCENCE OF BRICK)
 Due to this defect the wall looks dull and loses it aesthetic look.
 Can be prevented by brushing and washing the wall surface.
DEFECTS IN POST CONSTRUCTION PROCESS

24. o IRON STAINING
o WHITE SCUM (SILICATE DEPOSITS)
o LIME BLOW IN BRICKS
 Stains from external sources such as pollution,
organic growth or runoff. (Organic stains like algae,
mold or other organisms.
 Certain materials such as
copper,bronze,alliminium,synthetic succo or paint can
stain brickwork.

25. • COMPRESSIVE CAPACITY ONLY
• REQUIRED SKILLED LABOUR INVOLVEMENT
• INCREASED COST
• UNPREDICTABLE CASH FLOW
• EXPENSIVE FOR MASONRY WALLS
• HIGH MOISTURE ABSORBER
• LESS DURABILITY
• HIGH MAINTENANCE COST
• HIGH POSSIBILITY OF DAMPNESS
• A SLOW AND TEDIOUS PROCESS
• LOW TENSILE STRENGTH,CAN FAIL DURING
EARTHQUAKES
• POOR THERMAL INSULATION
GENERAL DEFECTS

26. • Emission of huge quantity of toxic elements such as
fumes containing suspend particulate matters rich in
carbon particles and high concentration of carbon
monoxides and oxides of sulphur that are harmful
to eye, lungs and throat.
• Surface mining instead for deep mining for brick making
resulting in large surface area being affected due to
excavation of soil.
• Deforestation also occurs in search of soil source for
clay brick manufacturing.
• Continuing use of clay bricks in construction industry
will lead to extensive loss of fertile top soil.
ENVIRONMENTAL POLLUTION FROM BRICK MAKING
OPERATIONS AND THEIR EFFECT ON WORKERS……..

27. 1.FLY ASH BRICKS
(raw materials:-dry ash, coarse sand, lime, gypsum,
cement)
-Manufactured using high end pre-programmed hydraulic machines.
-High and uniform compressive strength than traditional brick.
-Saving electricity.
-Eco-friendly .
-Low energy consumption (no need of fire operation)
-no need of skilled labours
uniform strength can obtain through the brick.
-High Affinity to cement mortar than traditional brick.
-dimensional accuracy through uniform shape
-Low water absorption
-High strength to weight ratio
-zero efflorescence
-consume less mortar in construction
REMEDIES

28. 2. COMPRESSED CEMENT SOIL EARTH
BLOCKS
(raw materials:-sandy soil, gravel soil)
River sand is not necessary
-cost effective
-low energy consumption(burning is not necessary)
-low environmental pollution
-reduction of transportation, time, cost
-less waste
-Non toxic
-fire proof
-high durability
-high strength
-especially designed for low income people