Lecture notes topic1 concrete_aug2015_part1

INTRODUCTION
TO
BUILDING MATERIALS
MAK/BLD62003/AUG2015
1

MATERIALS USED FOR BUILDING
CONSTRUCTION
CONCRETE
TIMBER
BRICKS &
BLOCKS
STONE
2
METAL
PLASTIC
GLASS

TOPIC 1:
CONCRETE
3

CONCRETE COMPOSITION
4
 Concrete is a heterogeneous material.
 Cement, sand gravel, rock aggregate and water.
 Ratio: 1:2:4 (cement: sand: aggregate).

CONCRETE RATIO
 REGULAR MIX
5

CONCRETE COMPOSITION
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 Materials are mixed &
poured into forms.
 Hardens as it sets.
 Naturally gray but may be
colored.
 Sometimes a 4th material is
added to the above mixture
for specific reasons:
Admixtures

DIFFERENCES BETWEEN
CONCRETE & CEMENT
7
 Concrete = signature material in
driveways, patios, basements & a
host of other household items.
 The world’s most widely used
building material.
 Produced from local resources,
with many grades of fine and
coarse aggregate to meet standard
& special mix needs.
 Products come in many forms and
applications each ~ when properly
formulated, handled, and placed,
can provided decades of service.
 Cement = an ultra-fine gray
powder, binds sand & rocks into
a mass or matrix of concrete.
 Cement is the key ingredient of
concrete.
 Made of: limestone, shale & clay
~ calcium oxide, silica, alumina,
& iron.
 Cement plants sit near quarries
with rocks bearing some or all of
these elements.
CONCRETE CEMENT

CONCRETE APPLICATIONS
 Residential & Non-Residential
 Structural element
 Finish material
 Subfloors, floors, walls, ceilings (cast or stamped into shapes)
8

CONCRETE
APPLICATIONS
9

CONCRETE APPEARANCE
Factors influencing:
 the composition of the concrete mix;
 the formwork used;
 any surface treatment after casting;
 the quality of workmanship.
10

CONCRETE FINISHES
SMOOTH FINISH TEXTURED FINISH
11

CONCRETE FINISHES
RIBBED & PROFILED
FINISHES
ABRADED/ POLISHED
FINISHES
12
• For exterior finishes i.e
concrete wall or flute
concrete unit.
• For internal
finishes i.e.
kitchen
area, hotel
lounge,
offices etc

EXPOSED AGGREGATE
FINISHES
13
• Suitable for
external finishes
i.e pedestrian
walkway, garden
pavement & etc.
CONCRETE FINISHES

CONCRETE PRODUCTION
Transport of sand, cement & aggregate to
batching plant
Concrete is directly casting on site or put
in silo batching plant before further
casting
Pour the concrete into formwork
Compact the concrete using vibrator
Permit curing
14

CEMENT MANUFACTURING
PROCESS
15

TYPES OF CONCRETE TEST
 SLUMP TEST (test for workability of fresh concrete)
 COMPACTING FACTOR TEST (test for workability
of fresh concrete)
 VEBE CONSISTOMETER TEST (test for workability
of fresh concrete)
 FLOW TEST (test for the flow value of fresh concrete)
16

(I) SLUMP TEST
 To measure the consistency or slump of fresh
concrete.
 To indicate the consistency and flowability of
fresh concrete
 To ensure that the concrete is suitable for that
particular reason.
 http://www.lmcc.com/concrete_news/0801/5-minute-classroom-slump.asp
17

SLUMP TEST : APPARATUS
18

SLUMP TEST PROCEDURE:
19
 VIDEO ON SLUMP TEST

SLUMP TEST PROCEDURE DIAGRAM
20

STEP 1: CLEAN INSTRUMENT
Make sure that all
instruments are
clean.
Put the cone on a
smooth and non-
absorbent surface.
21

STEP 2 : FILL THE CONE WITH CONCRETE FOR
3 LAYERS
Fill 1/3 of the cone with concrete.
Compact the layer evenly with the
rod.
22

Repeat. Fill 2/3 of the cone and then
the whole cone with concrete.
Compact the layer evenly with the
rod.
23

STEP 3 : REMOVE EXCESS CONCRETE
Remove excess concrete
from the top using the
tamping rod.
24

STEP 4 : RAISE THE CONE
Take out the cone vertically
without touching the
concrete.
25

STEP 5 : MEASURE THE CONCRETE
Lay a straight edge on
top of slump cone.
Measure the amount
of slump in inches
from the bottom of
the edge to the top of
slump.
26

SLUMP TEST RESULTS
27
True slump refers to general drop of the concrete mass evenly all
around without disintegration.
Shear slump indicates that the concrete lacks cohesion. It may
undergo segregation and bleeding and thus is undesirable for the
durability of concrete.
Collapse slump indicates that concrete mix is too wet and the mix
is regarded as harsh and lean.

COLLAPSE SLUMP
Water content of
concrete is too
high.
The concrete lacks
cohesion.
Thus, dose not
stick together very
well
28

SHEAR SLUMP
Top portion of the
concrete shears off and
slips sideways.
Water content in
concrete is too high
Regarded as harsh and
lean
29

TRUE SLUMP
1. 0-25mm slump
 Very dry
 Used for roadmaking
2. 10-40mm slump
 Medium workability mixes
 Used for foundations
3. 50-90mm slump
 High Workability mixes
 For normal reinforced concrete
30

(II) COMPACTING FACTOR TEST
 To determine the workability of freshly mixed
concrete.
31

METHOD OF CALCULATION
Consistency Compacting Factor
Very Dry 0.70
Very Hard 0.78
Hard 0.85
Plastic Hard 0.89
Plastic 0.92
Liquid 0.95
High Liquid 1.00
32

COMPACTING FACTOR: PROCEDURE
 HOW?
1. Concrete and water cement is mixed into upper hopper.
Concrete excess must be level accordingly.
2. The trap door of upper hopper is opened in order for the
concrete to fall into the lower hopper.
3. The trap door of lower hopper is opened for the concrete to
fall into the cylinder
4. The remaining concrete which remains above the top level
of cylinder is cut off by plane blades.
5. The concrete in the cylinder is weighed and labeled as
partially compacted concrete.
6. Fresh sample of concrete is filled into the cylinder and
vibrated until it is fully compacted.
7. It is then weighed and labeled as fully compacted
concrete.
33

COMPACTING FACTOR TEST:
APPARATUS
34

(III) VEBE TEST
 Measure the
consistency of stiff
to extremely dry
concrete.
 Consistency is the
duration needed for
a specific mass of
concrete to be
consolidated by
vibrating in any
shaped mould.
35

VEBE TEST
 VIDEO ON VEBE TEST
36

• A dynamic test and can be
used on concretes that are
too dry for the slump test.
• Test results are obtained
directly.
• Unsuitable for field use
due to the need to ensure
that all vibration is kept
within the test device.
• Only works for low slump
concretes.
• No analytical treatment
of the test method has
been developed.
BENEFITS OF VEBE TEST
37
ADVANTAGES DISADVANTAGES

 Also called flow table test
 To determine consistence and flow value
of fresh concrete
 Used for high workability concrete.
(IV) FLOW TEST
38

FLOW TEST
 VIDEO ON FLOW TEST
39

 Flow table with a grip and a hinge.
 Abrams cone, open at the top and at the bottom.
 Water bucket and broom for wetting the flow
table.
 Tamping rod.
FLOW TEST: APPARATUS
40

1. Wetted the flow table.
2. Place the cone in the centre of the flow table,
fill in with fresh concrete in two equal layer.
3. Tamping each layer for 10 times.
4. Wait for 30 seconds.
5. Lift up the cone to allow concrete to flow.
6. Lift up the flow table until it meets the stop,
drop down for 15 times.
7. Diameter of concrete is measured.
FLOW TEST: PROCEDURE
41

CONCRETE PROBLEMS
42

MAINTENANCE OF CONCRETE
43
 Raw concrete absorbs stains & generates dust.
 Painted & sealed concrete is impervious to stains
as long as the paint or finish remains intact.
 Sweep, damp mop or hose off where possible.
 Sealed countertops – use mild detergent, wipe
regularly.

MAINTENANCE FOR CONCRETE FLOORS:
 Avoid floor designs with sawcut patterns, since the narrow cuts in the
surface can trap dirt.
 Unless the floor is polished, always keep it protected with a good floor
sealer. This top layer of protection not only prolongs the life of your floor,
it can also enhance its appearance.
 For further protection against stains, dirt and abrasion, apply a good
commercial-grade floor wax designed for concrete floors. This sacrificial
finish will help to preserve the sealer and is easy to reapply if it begins
to wear. In areas of heavy traffic, such as entrances and foyers, reduce
maintenance and wear and tear by using floor mats, both inside and
outside of the entryways.
 Concrete floors are a good choice for pet owners because they won’t trap
pet dander and allow easy cleanup of muddy paws and pet accidents.
Just give the floor a few swipes with a broom, towel or mop.
 Follow the maintenance schedule recommended by the concrete
contractor to keep the floor looking its best.
 Only use cleaning solutions recommended by your contractor or the
manufacturer of the floor sealer or finishing wax. Avoid harsh cleaning
products.
44

MAINTENANCE FOR CONCRETE PATIOS:
 Daily preventive maintenance involves
cleaning and a good broom.
 Any large corn broom works well for the
outdoor areas and makes quick work of
sweeping away errant leaves, dirt left by shoes,
and the dust and dirt kicked up by wind or
rain.
 Sweeping the patio daily keeps this buildup of
dirt and dust at a minimum and makes giving
the patio a more thorough cleaning easier.
 A light buildup of dirt is easily scrubbed away
with a scrub brush and a hose with a high-
pressure nozzle.
 If dirt or mildew builds up in corners or where
water collects, use an environmentally-friendly
bleach or soap to scrub the concrete. Rinse it
with a jet nozzle and the concrete will look
nearly new. 45

MAINTENANCE FOR CONCRETE COUNTERTOPS:
Step 1 - Sealing and Coating
 Small holes that have a sponge like
appearance. This is because concrete is
porous - Need to fill these holes with the
penetrating sealer to help seal the
concrete surface. Concrete countertops
can be stained with both acid and grease
and sealing them will help prevent this.
 After they are sealed, use a concrete
coating sealer for shine. These come in
liquid and paste varieties and are applied
just like car wax and then buffed to a
shine.
 It will also protect from stains and
scratches but not make the countertops
impervious.
46

MAINTENANCE FOR CONCRETE COUNTERTOPS:
Step 2 - Regular Cleaning
 As with any household surface, regular cleaning
is the key to a long life.
 Dishwashing liquid on a sponge with warm water
is generally all you will need to clean them.
 While cleaning always watch for hairline cracks
that can allow water to penetrate.
 Use the penetrating sealer to seal them.
47

ADVANTAGES OF CONCRETE
 Can be molded
 Durable (long-lasting, sturdy)
 On-site or pre-fabrication
 Economical
 Fire-resistant
 Energy efficient
 Aesthetic
48

DISADVANTAGES OF CONCRETE
 Low tensile strength
 Brittle
 Volume instability
 Low strength/weight ratio
 Variable
49

FACTS ABOUT CONCRETE
 What is the purpose of cement in concrete?
It acts as a primary binder to join the aggregate into a solid
mass.
 What role does water play in producing concrete?
Water is required for the cement to hydrate and solidify.
 Why does concrete harden?
The chemical process called cement hydration produces
crystals that interlock and bind together.
 Why does concrete set (harden) slowly?
It takes time for the hydrated cement crystals to form
 How can you make concrete set:
faster? add calcium chloride or accelerator
slower? add sugar or "set retarder"
 Is concrete stronger in compression, tension, or the same in either?
It is stronger in compression.
50

CONCRETE STRENGTH & WORKABILITY
51

TUTORIAL QUESTION
 Choose three factors affecting the concrete
strength and workability & explain each factor.
 In a group of 5-6, present your findings to the
whole class.
52

Lecture notes topic1 concrete_aug2015_part1

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Lecture notes topic1 concrete_aug2015_part1