DISADVANTAGES IN

BRICK MASONRY CONSTRUCTION

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

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.

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.

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.

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.

DEFECTS IN SHAPESlumping• 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.

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.

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.

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.

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.

DEFECTS IN RAW MATERIALUnderfiring• 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.

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.

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.

DEFECTS IN APPEARANCESpalling• 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.

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.

Barmarks• Barmarks are the result of the firing process

where kiln gases do not reach the entire surface of a brick.

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.

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.

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

• 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

• 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.

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 wallParapet wallManhole 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

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.

• 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

• 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……..

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 laboursuniform 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

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