2. īCement mortar is a material
used for masonry construction
to fill the gap between bricks or
blocks of rock
īMortar binds bricks and give
strength, stability and durability
of building structures
CEMENT MORTER
3. Motor is a mixture of binding material, sand and
water, it is similar to concrete but it does not contain
course aggregates
īLime mortar
īcement mortar
īSurkhi mortar
īMud mortar
īPozzolona mortar
Mortar becomes hard when sets resulting as hard
aggregate structure.
TYPES OF MORTERS USED
5. Various proportion used for
different purpose
Sl. No. Works Cement : sand
Proportion
1 Masonry work 1:6 to 1:8
2 Plastering work 1:3 to 1:4
3 Plastering
concrete
1:3
4 pointing 1:2 to 1:3
6. CONCRETE
HISTORY OF CONCRETE
ī 2000 B.C.: Egyptians used cement in
mortar when making Pyramids
ī 27 B.C.: Roman cement made of lime and
volcanic ash
ī 1756: Smeaton rebuilt Eddystone
Lighthouse
ī 1824: Joseph Aspdin discovered and
patented âPortlandâ cement
7. Ingredients' of CONCRETE
ī There are three basic ingredients in the
concrete mix:
ī Portland Cement.
ī Fine aggregates(sand and fine
particles)
ī Course aggregates (rock and stones)
ī Water
Aggregates may be course or fine
Aggregate consists of large chunks of material in a
concrete mix, generally a coarse gravel or crushed
rocks such as limestone, or granite, along with
finer materials such as sand. Cement, most
8. Specification of Concrete
Concrete are specified as follows :
ī Concrete are specified by mix ratio.
ī The strength of this concrete mix is determined by
the proportion on which these cement, sand, stones
or aggregates are mixed.
ī There are various grades of concrete available in the
market based on these ratios.
ī Some of them are: M10, M20, M30, M35, etc.
9. BEST PROPRTION OF
CONCRETE
ī A concrete mixture ratio of 1 part cement, 3
parts sand, and 3 parts aggregate will produce a
concrete mix of approximately 3000 psi.
ī Mixing water with the cement, sand, and stone
will form a paste that will bind the materials
together until the mix hardens.
11. COMMON WATER CEMENT
RATIO
ī A lower ratio leads to higher strength and
durability
ī But may make the mix difficult to work with and
form
ī Workability can be resolved with the use of
plasticizers or super-plasticizers
ī Water cement ratio of 0.45 to 0.6 is generally
used in nominal mix concrete such as M10, M15
and M20 concrete construction
13. Workability Of concrete
ī§ A concrete is said to be workable if it is easily
ī§ Transported,
ī§ Placed,
ī§ Compacted
ī§ And finished
ī Without any segregation.
Workability is a property of freshly mixed concrete,
and a concrete is a mixture of cement, aggregate,
water & admixture.
14. Factors affecting the workability of
concrete
īwater content
īcement concrete
ī Size of sand and aggregate, such
as
ī Size,
ī Ghape,
ī Grading,
ī Mix design ratio
ī And use of admixtures.
Each and every process and materials involved in
concrete mixing affects the workability of
concrete.
15. Slump test of concrete
Concrete slump test is carried out from batch to
batch to check the uniform quality
of concrete during construction. The slump test is
the most simple workability test of concrete,
involves low cost and provides immediate results
16. ī Concrete Slump Test Procedure
ī Firstly, the internal surface of the mould is cleaned
carefully. Oil can be applied on the surface.
ī The mould is then placed on a base plate. The base plate
should be clean, smooth, horizontal and non-porous.
ī The mould is filled with fresh concrete in three layers.
Each layer is tamped 25 times with a steel rod. The
diameter of this steel rod is 5â8 inch. The rod is rounded
at the ends. The tamping should be done uniformly.
ī After filling the mould, excess concrete should be
removed and the surface should be leveled. When the
mould is filled with fresh concrete, the base of the
mould is held firmly by handles.
ī Then the mould is lifted gently in the vertical direction
and then unsupported concrete will slump. The
decrease in height at the centre point is measured to
nearest 5mm or 0.25 inch and it is known as âslumpâ.
17. īCautions Required During
Concrete Slump Test
ī Inside of the mould and base should be
moistened before every test. It is necessary to
reduce surface friction.
ī Prior to lifting mould, the area around the base of
the cone should be cleaned from concrete which
may be dropped accidentally.
ī The mould and base-plate should be non-porous.
ī This test should be performed in a place free of
vibration or shocks.
ī The concrete sample should be very fresh, the
delay must be avoided and the test should be
done just after mixing.
18. Compression test of concrete
Compression testing M/C Concrete under test Concrete fails in
PressureThese specimens are tested by compression testing
machine
After 7 days curing or 28 days curing.
Load should be applied gradually at the rate of 140 kg/cm2
per minute till the Specimens fails.
Load at the failure divided by area of specimen gives the
19. ī curing: The concrete is flooded, ponded, or mist
sprayed.
ī This is the most effective curing method for
preventing mix water evaporation.
ī Make sure you allow proper time for water curing.
Water retaining methods
ī Use coverings such as sand, canvas, burlap, or
straw that are kept continuously wet.
ī Unless required for test at 24 hours,
the cube should be placed immediately after
demoulding in the curing tank or mist room
ī The curing temperature of the water in
the curing tank should be maintained at 27-30°C
ī If curing is in a mist room, the relative humidity
should be maintained at no less than 95%.
20. What is an Aggregate?
ī We should definitely know about the aggregates
because of the following
ī Aggregates are the important constituents of the
concrete
ī which give body to the concrete and also reduce
shrinkage
ī Aggregates occupy 70 to 80 % of total volume of
concrete
ī So, can say that one should know definitely about the
aggregates in depth to study more about concrete.
21. Classification of Aggregates as per Size and Shape
ī Aggregates are classified based on so many
considerations, but here we are going to discuss about
their shape and size classifications in detail.
Based on the shape
īRounded aggregates
īIrregular or partly rounded
aggregates
īAngular aggregates
īFlaky aggregates
īElongated aggregates
īFlaky and elongated aggregates
Based on the
shape
īFine aggregates
īCourse
aggregates
22. Fine Aggregate
ī When the aggregate is sieved through
4.75mm sieve
ī The aggregate passed through it called as
fine aggregate
ī Natural sand is generally used as fine
aggregate
ī Silt and clay are also come under this
category
ī The soft deposit consisting of sand, silt and
clay is termed as loam
ī The purpose of the fine aggregate is to fill
the voids in the coarse aggregate and to act
as a workability agent.
24. Coarse Aggregate
īWhen the aggregate is sieved
through 4.75mm sieve, the
aggregate retained is called coarse
aggregate
īGravel, cobble and boulders come
under this category
īThe maximum size aggregate used
may be dependent upon some
conditions
īIn general, 40mm size aggregate
used for normal strengths and
20mm size is used for high
26. Grading curve presented by sieve analysi
Coarse aggregates used in concrete making contain aggregates of various sizes.
This particle size distribution of the coarse aggregates is termed as âGradationâ.
The sieve analysis is conducted to determine this particle size distribution. It is
this matrix that is vulnerable to all ills of concrete.
27. WHY TO DETERMINE FINENESS MODULUS?
ī Fineness modulus is generally used to get an idea of how coarse
or fine the aggregate is
ī More fineness modulus value indicates that the aggregate is
coarser
ī And small value of fineness modulus indicates that the aggregate
is finer
ī Fineness modulus of different type of sand is as per given below
Type of Sand Fineness Modulus Range
ī Fine Sand 2.2 â 2.6
ī Medium Sand 2.6 â 2.9
ī Coarse Sand 2.9 â 3.2
ī Generally sand having fineness modulus more than 3.2 is not used for making good
concrete.
ī Fineness modulus can also be used to combine two aggregate to get the desirable
grading.
28. īAggregate comprises about 85 % volume of mass concreteâ
īâConcrete contains aggregate up to a maximum size of 150 mm
ī
īââWay particles of aggregate fit together in the mix, as influenced by the
gradation, shape, and surface textureâ
īâGrading effects workability and finishing characteristic of fresh
concrete, consequently the properties of hardened concrete
īâGood grading implies, sample of aggregates containing all standard
fractions of aggregate in required proportion such that the sample
contains minimum voids
īâWell graded aggregate containing minimum voids will require minimum
paste to fill up the voids in the aggregate
īâMinimum paste means less quantity of cement and less quantity of
water, hence increased economy, higher strength, lower-shrinkage and
greater durability
29. HOW TO DETERMINE FINENESS MODULUS?
Following procedure is adopted to calculate
fineness modulus of aggregate:
PROCEDURE
īSieve the aggregate using the appropriate sieves
(80 mm, 40 mm, 20 mm, 10 mm, 4.75 mm, 2.36 mm,
1.18 mm, 600 micron, 300 micron & 150 micron)
īRecord the weight of aggregate retained on each
sieve.
īCalculate the cumulative weight of aggregate
retained on each sieve
īCalculate the cumulative percentage of aggregate
retained.
īAdd the cumulative weight of aggregate retained
and divide the sum by 100.
30. Sieve Size
Weight of
sand
Retained (g)
Cumulative weight
of sand retained (g)
Cumulative
percentage of sand
retained (%)
80 mm â â â
40 mm â â â
20 mm â â â
10 mm 0 0 0
4.75 mm 10 10 2
2.36 mm 50 60 12
1.18 mm 50 110 22
600 micron 95 205 41
300 micron 175 380 76
150 micron 85 465 93
Pan 35 500
Total amount = 500
Total
= 246
So Fineness Modulus = 246/100 = 2.46
Calculation for So Fineness Modulus