Laboratory Tests on Construction materials

1
Laboratory Tests on Construction materials

• Dr.K.Lakshmipathi,
• Centre Head,
• Centre for Rural Infrastructure

2
Materials-

• . Bricks
• . Cement
• . Aggregates
• . Concrete
• . Steel

3
Tests on common building bricks

1. Dimensions and tolerances test.
2. Compressive strength test.
3. Water absorption test.
4. Efflorescence test.

C 303. 17 to 18
8
4
Testing of Bricks

• Before using the bricks for any important
  engineering work, they should be tested to know
  their suitability for the work.
• For testing the bricks, their samples should be
  taken.
• In general 50 bricks are selected for every
  consignment or stacking for 50,000 bricks.

C 303. 17 to 18
4
5
Methods for selection of brick samples

• Sampling in motion
• Some samples of bricks shall be taken when bricks
  are
• being moved as in the case of loading or
  unloading at
• regular intervals so as to get a true
  representation of the
• whole quantity.

C 303. 17 to 18
5
6
(2) Sampling from a stack

• Sample shall be taken out at random from a stack
• of bricks.
• The number of bricks required for the test shall
  be
• selected from the top, the sides accessible
  and
• interior of the stack.

C 303. 17 to 18
6
7
Contd

• The sample taken by either of the two methods,
  shall be
• stored in a dry place until the tests are
  completed.

C 303. 17 to 18
7
8
Compressive strength test

• Purpose
• This test is performed to know the crushing
  strength of
• bricks which should not be less than the
  specified limit.

C 303. 17 to 18
9
9
Method

• In this test, five bricks out of the samples
  already taken are
• selected at random.
• They are immersed in water at room temperature
  for 24
• hours.
• Then ,the bricks are taken out from water and
  wiped free
• from surplus moisture at room temperature.

C 303. 17 to 18
10
10
Contd

• After this, their frogs and all voids in the bed
  and face shall
• be filled with cement mortar 11 (1 cement
  ,1 clean
• course sand of grain size 3mm and down )

C 303. 17 to 18
11
11
Contd

• The bricks shall then be stored under damp sacks
  for 24 hours.
• After the expiry of this period, they shall be
  immersed in water for
• three days.

C 303. 17 to 18
12
12
Contd

• At the end of three days, the samples of bricks
  shall be
• taken out, wiped dry.
• Then, each brick shall be placed between two or
  three ply
• thin polywood sheets, each approximately 0.3
  cm thick, with
• flat surfaces horizontal and the mortar filled
  face upward.

C 303. 17 to 18
13
13
Contd

• This arrangements shall be carefully centered
  between the
• plates of compression testing machine.
• The load shall be applied at a uniform rate of
  140kg/sq.cm
• per minute until failure occurs.
• The maximum load at failure divided by the
  surface area of
• the brick on which load is acting is taken
  at its compressive
• strength.

C 303. 17 to 18
14
14
Result

• The arithmetic mean of the compressive strength
  of five such
• tests shall be taken as the compressive
  strength of the lot or
• stack where from the samples have been taken.

C 303. 17 to 18
15
15
Note

• The compressive strength of any individual brick
  shall not fall below
• average compressive strength specified for
  the corresponding class
• of brick by more than 20.

C 303. 17 to 18
15
16
Contd

• Common building brick shall have a minimum
  compressive
• strength of 35kg/cm2.

C 303. 17 to 18
17
17
Water absorption test

• Also known as 24hr, immersion cold water test.
• Purpose.
• This test is performed to know the water
  absorption capacity
• of bricks.

C 303. 17 to 18
18
18
Method

• In this test, five bricks shall be selected at
  random out of the
• sample of bricks already taken.
• They are then dried in a ventilated oven at 105o
  to 115oc till they
• attain almost constant weight.

C 303. 17 to 18
19
19
Contd

• The specimens shall then be cooled to room
  temperature and weighed.
• Let it be W1 un its.

• The dry and cooled specimens shall be
  completely immerse in
• clean water at 27o_ 2oc for 24 hours.

C 303. 17 to 18
20
20
Contd

• Each specimens shall then be removed, the surface
  water
• wiped off with a damp cloth and then weighed.
• Weighing shall be completed within three minutes
  after
• removing the specimen from water.
• Let it be W2 units.

C 303. 17 to 18
21
21
Contd

• Then the water absorption capacity of the
  specimen is found as given below.
• Let W1 Weight of dry specimen.
• W2 Weight after soaking in water
  i.e., weight of
• wet specimen.

Percentage water absorption ( by dry wt) W2-W1x
100
W1
C 303. 17 to 18
22
22
Result

• The average of the five specimens should be taken
  as the
• water absorption capacity of the lot or
  stack of bricks from
• where the samples have been taken.

C 303. 17 to 18
23
23
Note

• The average water absorption of common building
  bricks
• shall not be more than 20 up to class 1 2
  and 15 for
• higher class by weight after immersion in
  cold water for 24 hours.

C 303. 17 to 18
24
24

• Tests on Sand
• Definition
• Sand is an Inorganic Material which is Sharp,
  Angular
• and Rounded grains of Silica (SiO2).

25
FUNCTIONS OF SAND

• Reduce the shrinkage of binding material.
• Prevents development of cracks in the mortar
  after
• drying.
• Helps in hardening of fat lime.
• Making mortars of desired grade

26
Classifications of sand

• NATURAL SAND
• ARTIFICIAL SAND

27

• Natural sand is of 3 types
• 1.River sand
• 2. Pit Sand
• 3. Sea Sand

28
RIVER SAND PIT SAND SEA SAND
Obtained from beds and bank of rivers. Obtained from pits dug. Obtained from sea shore.
2) These particles are fine, round and polished. 2) These particles consists of sharp angular grains free from salts. 2) These particles consists of fine, round polish.
3) Colour is white globular shape smaller in size than pit sand and it is ready to use . 3) It should be screened washed before using it. 3) It attracts moisture from the atmosphere cause permanent dampness.
29
Artificial sand

• Artificial sand is obtained by crushing stones
  and
• gravels to powder.

30

• Bulking Of Sand
• Increase in volume of sand due to presence of
• surface moisture is called Bulking of sand.

C-05/C-303.25
31
Percentage of bulkage allowance to be made

• In preparing mortars and concrete, it is
  necessary to determine the percentage of bulking
  of sand. Accordingly, allowances should be made
  for the bulkage by adding extra amount of sand.

32
The volume of bulking of sand for various
moisture content are given below

• Bulking of sand various moisture contents

33
Table ( continued .)
34
(No Transcript)
35
Contd..

• When the sand is moistened ,every particle of
  it gets covered with a thin film of surface
  moisture . This moisture tends to keep the
  particles away from one another and cause bulking
  (increase in volume )of sand

36
Contd..

• It has been observed that with the additions
  of 5 to
• 6 of moisture content by weight , the
  volume of dry
• sand increases by 18 to 38.
• The bulking of fine sand is greater than that
  of the
• coarse sand

37
Contd..

• If the percentage of moisture content is
  increased beyond 10 the bulking of sand starts
  decreasing and when sand in completely saturated,
  its volume is equal to that of dry sand

38
Tests on Cement

• The cement is obtained by burning at a very high
  temperature of a mixture of calcareous and
  argillaceous materials.
• The mixture of ingredients should be intimate and
  they should be in correct proportion.
• The calcined product is known as clinker. A small
  quantity of gypsum is added to clinker and it is
  then pulverized into very fine powder which is
  known as cement.

39
Contd..

• Cement is a fine, soft, powdery-type substance.
  It is made from a mixture of elements that are
  found in natural materials such as limestone,
  clay, sand and/or shale. When cement is mixed
  with water, it can bind sand and gravel into a
  hard, solid mass called concrete.

40

• Cement History
• In 1824, Joseph Aspdin, a British stone mason,
  heated a mixture of finely ground limestone and
  clay in his kitchen stove and ground the mixture
  into a powder to create a hydraulic cementone
  that hardens with the addition of water.

41
continued..
Fig. 1 Construction with cement
42
Contd..

• He took a patent for this cement
• A variety of sandstone is found in abundance in
  Portland in England.
• Hence it called as ORDINARY PORTLAND CEMENT
• ( O P C )
• The first cement factory was installed at Tamil
  Nadu in India 1904 by South India Industry
  Limited.

43

• Do you know?
• Four essential elements are needed to make
  cement. They are Calcium, Silicon, Aluminum and
  Iron.
• Calcium (which is the main ingredient) can be
  obtained from limestone, whereas silicon can be
  obtained from sand
• Aluminum and iron can be extracted from bauxite
  and iron ore, and only small amounts are needed.

44
CHEMICAL COMPOSITION OF CEMENT

• The raw materials used for the manufacture of
  cement consist mainly of lime, silica, alumina
  and iron oxide.
• These oxides interact with one another in the
  kiln at high temperature to form more complex
  compounds.
• The relative proportions of these oxide
  compositions are responsible for influencing the
  various properties of cement, in addition to rate
  of cooling and fineness of grinding.

45
Table 1 Chemical composition of cement
Oxide Percent content
CaO (Lime) SiO2 (Silica) Al2O3 (Alumina) Fe2O3 (Iron oxide) MgO (Magnesia) Alkalies(K2O,Na2O) SO3 (Sulphur trioxide) 60-67 17-25 5-8 0.5-6 0.1-4 0.2-1.0 1-3
46

• FUNCTIONS OF CEMENT INGRADIENTS
• LIME(CaO)
• Major ingredient of cement
• Excess quantity makes the cement unsound
• If it is less, it decreases the strength and
  allows the cement to set quickly

47
Contd..

• SILICA(SiO2)
• An important ingredient which gives strength to
  cement.
• If it is in excess allows the cement to set
  slowly.

48
Contd..

• ALUMINA(Al2O3)
• This imparts quick setting time to the cement.
• If it is in excess quantity weakens the cement.
• It also lowers the temperature of clinkers.

49
Contd..

• IRON OXIDE(Fe2O3)
• It helps the fusion of the raw materials during
  burning state.
• It gives colour, strength and hardness to cement.

50
Contd..

• MAGNESIUM OXIDE (MgO)
• If present in small quantity, imparts hardness
  and colour to cement.
• If in excess quantity, weakens the cement.

51
Contd..

• SULPHUR TRIOXIDE(SO3)
• A very small quantity is required in the
  manufacturing of cement.
• If it is in excess, it makes the cement unsound.

52
Contd..

• ALKALIES
• A small quantity is required.
• Alkalies and other impurities present in raw
  materials are carried by the flue gases during
  heating.
• If it is in excess quantity efflorescence is
  caused.

53
Laboratory Tests on Cement

• Fineness of cement
• Consistency of cement
• Setting times of cement
• 4. Soundness of cement
• Compressive Strength of cement
• Tensile strength of cement

54
Fineness of cement
The fineness of cement is a measure of the size
of cement. It is necessary to check the proper
grinding of cement, it has a influence on the
behavior of cement.
55
Procedure to find the fineness of cement

• Breakdown any air set lumps in the cement sample
  with finger and mix it uniformly.
• Weigh 100gm of the cement to the nearest 0.01g
  and place it on a clean and dry 90? IS sieve with
  pan attached.
• Continuously sieve the sample by holding the
  sieve in both hands for 15 minutes with a gentle
  motion.
• 4. While sieving it, ensure that there is no
  spilling of the cement.

56
Contd..

• Do not use washers, shots and slugs on the sieve.
• Slightly brush under side of the sieve after
  every 5 minutes of sieving.
• Find the weight of residue on the sieve after the
  value as a percent of the original sample taken.
• Fineness of cement in represented as the percent
  of material passing through the sieve

57
Specimen calculation
Weight of cement taken W1
g Weight of residue W2
g (Fineness of the cement should not more then
10)
Percentage of residue
Result
of passing of given sample 100 - of residue

58
Normal consistency of cement
59
Definition

• Normal consistency is defined as that
  percentage of water required to produce a
  cement paste of standard consistency.

60
VICAT APPARATUS
1
Fig 4
61
Procedure to find the normal consistency of
cement

1. Take 300gm of cement sample and place at on a
   non-absorbent plate.
2. Take 25 of water by weight of cement as first
   trial and mix it thoroughly with cement using
   gauging trowels. Ensure that the time of gauging
   shall be with in 3 to 5 minutes. The time of
   gauging shall be reckoned from the instant water
   is added to cement to that paste is filled in the
   mould.

62
Contd

• Keep mould on a non absorbent plate. Apply a thin
  coat of oil inside the mould.
• 4. Fill the vicats mould with cement paste at a
  stretch and tamp the mould so as to make the
  cement spread uniformly in the mould. Strike off
  the excess cement plate and level the surface of
  mould with spatula.
• 5. Fix the plunger of 10mm dia x 50mm long to the
  plunger holder of the apparatus. Gently lower the
  plunger to touch the moulds top surface and
  level it quickly. Due to the weight of header and
  holder the plunger settles to the cement paste.

63
Contd

• Note the plunger penetration reading on the scale
  of apparatus. The recorder penetration value is
  reckoned from the bottom of mould.
• Remove the plunger and cement paste from the
  mould.
• Take sample of cement and repeat the entire
  process with 27 of water and note down the
  plunger penetration.

64
Contd

• 9. Repeat the above process with varying of
  water and
• note the penetration of plunger till the
  penetration value is
• 5 to 7 mm. measured from the bottom of the
  mould
• Note The standard consistency of ordinary
  Portland
• cement is 30 to 35 by weight of cement

65
Specimen calculation
Weight of cement taken g Percentage of water
added Initial reading on vicat scale in
mm Final reading on vicat scale in
mm Penetration of plunger measured from
bottom of mould in mm
66
Result
The standard consistency of mould _____

67
Initial and Final setting time of cement
68
Theory

• When water is added to cement, the paste starts
  stiffening and gaining strength, simultaneously
  loosing its plasticity. Two stiffening states are
  identified as initial and final setting times
  respectively.
• Initial setting time is the interval between
  the addition
• of water to cement and the stage when needle
  
• ceases to penetrate completely.
• This time should be about 30 minutes for
  ordinary
• cement.

69
Procedure

• Preparation of test block
• Prepare a neat cement paste by mixing the cement
  with 0.85 times the water required to give a
  paste of standard consistency.
• 2. Start stop watch at the instant when water is
  added to cement. Thoroughly mix cement and water
  using gauging trowels till required uniformity is
  attained in mixing.

70
Contd

• Fill the mould completely and smoothen the
  surface of the paste by making it level with the
  top of the mould. The cement block thus prepared
  in the mould is the test block.
• Note
• Clean appliance shall be used for mixing.
• All apparatus shall be free from vibration during
  the test.
• Care shall be taken to keep the needle straight.

71

• (B) Initial setting time
• Place the test block with porous plate at bottom,
  under the rod bearing the needle (c) as shown in
  the fig. 1
• Lower the needle gently until it comes in contact
  with the surface of test block and quickly
  release, allowing it to penetration into test
  block.

72
Contd

• Repeat this procedure at regular intervals of
  time until the needle, when brought in contact
  with the test block and released as above fails
  to pierce the block for 5 to 7 mm measured from
  the bottom of the mould.
• 4. The period elapsed between the time when water
  is added to the cement and the time at which the
  needle fails to pierce the test block to a point
  5 to 7 mm measured from the bottom of the mould
  shall be reported as initial setting time.

Note The initial setting time of ordinary
Portland cement is 30 minutes
73

• (c) Final setting time
• Replace the needle c of the vicat apparatus
  attachment.
• Prepare the test block according to the procedure
  given above.
• The cement shall be considered as finally set
  when, upon applying the needle gently to the
  surface of the test block, the needle makes an
  impression there while the attachment fails to do
  so.

74
Contd

1. The period elapsing between the time when water
   is added to the cement and the time at which the
   needle makes an impression on the surface of the
   test block while the attachment fails to do so
   shall be the final setting time.

Note The final setting time of ordinary Portland
cement is 600 minutes
75
Specimen calculation Sample sample of
OPC Water required to prepare a cement paste of
standard consistency p Weight of cement
required for 1 mould 300 g
Weight of water added to cement (0.85p x
300g ml) 100
76
( A) Initial setting time Time elapsed since
the water is added to cement min Initial
reading on vicat apparatus in min (a)
Final reading on vicat apparatus in mm (b)
Penetration of vicat needle measured from The
bottom of mould in mm (b-a)
77
Result

1. Initial setting time for the given cement
   sample __________ min
2. Final setting time for the given cement
   sample __________ min

Note The result of initial and final setting
time shall be reported to nearest five minutes.
78
Compressive strength of cement
79

• Procedure
• preparation of test cubes
• As per I.S specification cement mortar of
  13 is used.
• The following quantities of materials
  required for each cube
• Cement 185g
• ii) Standard sand 555g185g each of
  grade-1(Size-2mm
• to 1 mm),
  grade-2(Size - 1 mm to
• 0.5mm),
  grade-3(Size-0.5 mm to 90
• microns)

80
Contd

• iii) Water (P/4)3.5 of combined weight
  of cement sand,
• where p is the percentage of water required
  to produce a paste of standard consistency.

81
Contd..

1. Weight the cement and standard sand of three
   grades in required proportion and place them on a
   non absorbent plate.
2. Mix the ingredients in dry condition with gauging
   trowels, add the measured quantity of water to
   the dry matrix and mix them thoroughly applying
   sufficient pressure till uniform consistency is
   achieved. Ensure the time taken for mixing shall
   not exceed 4 minutes.

82
Contd

• 3. place the entire quantity of mortar into
  the mould and tamp the mould using 12mm dia.
  tamping rod by 25 times. place the mould on the
  mould housing unit of the cement mortar vibrator
  as shown in fig.2 and clamp all the check nuts
  and spring washers tightly.

83
Contd..
4. Vibrate the cube for a period of 2 minutes.
Remove the mould from the vibrator and keep it
on a dry area. Repeat the process for casting
nine cubes.
Fig 2 Mortar vibrator
84
Contd..

• 5. Demould the cubes after 24 hours and transfer
  them to curing tank. keep the cubes in curing
  tank for 28 days and find the compressive
  strength of cement as per the standard procedure
  at the age of 3,7and 28days.

85
Fig. 3
86
Specimen calculation Area of the
cubes (A) 7.07cmx7.07cm 5000sq.mm
Crushing load (W)
Compressive strength (W / A)
N/sq. mm
87
Result compressive strength of cement at
the age of 3days

7days
28 days
88
Soundness test
89
4
90
Contd..

• The apparatus is shown in fig . 4, it consists
  of a small split cylinder of spring brass or
  other suitable metal.
• 2. It is 30mm in dia and 30mm high.
• 3. On either side of the split are attached two
  indicator arms 165mm long with pointed ends.

91
Contd..

• 4. Cement Is gauged with 0.78 times the water
  required
• for standard consistency(0.78p) in a
  standard manner
• and filled into the mould and kept on a
  glass plate.
• 5. The mould is covered on the top with another
  glass
• plate.
• 6. The whole assembly is immersed in water at a
• temperature of 270C - 320C and kept there for
  24 hrs.

92
Contd..

• Measure the distance between the indicator
  points.
• Submerge the mould again in water. heat the water
  and bring to boiling point in about 25-30 minutes
  and keep it boiling for 3hours.
• 9. Remove the mould from the water, allow it to
  cool and measure the distance between the
  indicator points.

93
Contd..

• 10.The difference between these two measurements
  
• represents the expansion of cement. This
  must not
• exceed 10mm for ordinary, rapid hardening
  and low
• heat Portland cements.
• 11.If in case , the expansion is more than 10mm
  as tested
• above, the cement is said to be unsound.

94
Workability

• The strength and quality of concrete depends on
  w/c ratio
• Excess w/c ratio improves workability , but
  reduces strength and durability
• Workability is the ease with which concrete is
  handled , transported and placed in forms with
  minimum loss of homogeneity

95
Hydration of cement

• When water is added to cement, chemical
  reaction takes
• place between water and cement . This reaction
  is known as
• hydration of cement
• Exothermic in nature and releases heat

96

• Process of hydration is faster in early stages
• During curing period of 28 days , 90 of
  hydration takes place
• Approximately 50 of water by mass of cement
  is required for complete hydration

97
Factors influencing rate of hydration

• Type of cement
• Fineness of cement
• Temperature at the time of mixing

98
Water Cement ratio

• The ratio of amount of water to the amount of
  cement by weight is known as water cement ratio
  .

99
Effects of W/C ratio

• The strength and quality of concrete depends on
  w/c ratio
• Excess w/c ratio improves workability , but
  reduces strength and durability
• Addition of extra one lit of water per bag of
  cement reduces strength of concrete by 1.5 N/mm2

100
Contd

• W/C ratio for structures exposed to weather
  should be carefully decided
• For structures which are regularly subjected to
  wetting and drying , w/c ratio by weight should
  be 0.45 to 0.55
• For structures which are continuously under water
  , w/c ratio by weight should be 0.55 to 0.65

101

• Advantages of low water/cement ratio
• Increased strength
• Lower permeability
• Increased resistance to weathering
• Better bond between concrete and reinforcement
• Reduced drying shrinkage and cracking
• Less volume change from wetting and drying

102
Fig.1 Relation between the compressive strength
to water cement ratio
103
Workability

• Ease with which concrete is handled , transported
  and placed in forms with minimum loss of
  homogeneity
• If more water is added , it improves workability
  but reduces strength and durability

104
Contd.

• Can be improved by changing the proportions of
  fine coarse aggregate
• Can be improved by adding certain admixtures
• Can be measured by slump test, compaction factor
  test

105
Fig.2 Measurements of workability Slump
106
Slump
(d)
Fig.3 Measurements of workability Slump
107
Tests on Aggregates

• Types of Aggregates
• Fine aggregate
• Coarse aggregate

108
Coarse aggregate

• Retains on IS sieve 4.75 mm
• Stone chips are commonly used

109
Characteristics of coarse aggregate

• Angular, dense, free from flaky surface and
  impurities
• Should have high strength against crushing
• Nominal size is 20 mm for RCC works
• Nominal size is 40 mm for mass concrete

110
Functions of coarse aggregate

• Makes solid and hard mass of concrete
• Increases strength of concrete
• Occupies major space and makes concrete
  economical

111
Water absorption

• Minute voids are formed in rocks during formation
  and also due to atmospheric action
• The pores vary in size and distributed throughout
  the body of rock
• Porosity of commonly used rocks varies from 0 to
  20
• Percentage of water absorbed by the aggregate
  when immersed in water is known as Water
  absorption of aggregate

112
Importance of water absorption

• Quantity of porosity and water absorption of
  aggregate will affect water cement ratio
• Affects workability of concrete
• When aggregate is dry , hydration will not be
  complete , lowers the workability and reduces
  the strength of concrete

113
Contd.
Contd.

• If the aggregate is fully saturated , water
  content in concrete will be more and concrete
  will become honey combed, reduces strength and
  density of concrete
• The knowledge of Water absorption of aggregate
  is important for concrete mix design calculation

114
Bulking of fine aggregate

• Increase in volume of fine aggregate caused by
  presence of water is known as bulking
• Bulking depends on percentage of moisture and
  fineness of sand
• Bulking increases gradually with increase in
  moisture content up to certain point and
  decreases to its original volume with further
  increase in moisture content

115
Contd.

• For ordinary sand bulking varies from 15 to 30
• Finer sand bulks considerably
• If sand is measured by volume and no allowance is
  made for bulking, the mix will be richer

116
Sieve analysis

• Is an operation of dividing a sample of aggregate
  into fractions , each consisting of particles of
  same size
• I.S Sieves of aperture size used for sieve
  analysis are 80mm, 40mm, 20 mm, 10mm, 4.75 mm,
  2.36 mm , 1.18mm , 0.6mm, 0.3mm, 0.15mm .

117
Contd.

• From sieve analysis , the particle size
  distribution is found
• Grading pattern of aggregate is assessed
• Useful in the design of concrete mixes

118
TESTS ON AGGREGATE
119
1. SIEVE ANALYSIS OF AGGREGATES

• Each type of aggregate test requires a
• specified aggregate size (E.g. 10-12.5 mm for
  
• crushing test)
• Each bituminous mix type has a recommended
• aggregate gradation ( passing 26.5 mm in
• 55-90 for GSB1)
• So aggregate is passed through a set of sieves
• to get material of various sizes

• Procedure
• Bring the sample to an air dry condition
• either by drying at room temperature or in
• oven at a temperature of 100oC to
• 110oC.Take the weight of the sample.
• Clean all the sieves and sieve the sample
• successively on the appropriate sieves
• starting with the largest.
• Shake each sieve separately over a clean
• tray.
• On completion of sieving note down the
• weight of material retained on each sieve.
• Report the results as cumulative percentage
• by weight of sample passing each of the
• sieves.

Sieves and Sieve-shaker
120
Observation Sheet
121

• Significance
• Aggregate crushing value provides a relative
  measure of resistance to crushing under a
  gradually applied compressive load
• Aggregates subjected to high stresses during
  rolling and severe abrasion under traffic
• Also in India very severe stresses come on
  pavements due to rigid tyre rims of heavily
  loaded animal drawn vehicles

Test Set-up
122

• Procedure
• Surface dry aggregates passing 12.5 mm and
  retained on 10 mm selected
• 3.25 kg aggregate required for one test sample
• Cylindrical measure filled with aggregates in 3
  layers, tamping each layer 25 times
• After leveling the aggregates at the top surface
  the test sample is weighed
• The cylinder is now placed on the base plate
• The cylinder with the test sample and plunger in
  position is placed on compression machine
• Load is applied at a rate of 4 tonnes per minute
  upto 40 tonnes
• The crushed aggregate is taken out, sieved
  through 2.36 mm IS sieve and weighed to get
  material passing
• Aggregate crushing value W2100/W1 W2
  Weight of crushed material,
• W1Total weight of sample

• Load Application
• Sample being loaded in the compression machine at
  4 T per minute for 10 minutes (upto 40 T)

123
Observation Sheet

• Discussion
• Indirect measure of crushing strength
• Low value indicate strong aggregates
• Surface course need more strength than base
  course
• Should not exceed 30 for cement concrete
  surface , and 45 for others

Specifications
124
3. Aggregate Impact Test

• Significance
• This test assesses the suitability of aggregate
  as regards the toughness for use in
• pavement construction
• Road aggregates subjected to pounding action
  due to traffic loads so possibility of
• breaking
• Should be tough enough- so proper aggregates to
  be used Suitability to be checked
• by laboratory tests

• Procedure
• 1. Aggregate passing through 12.5 mm IS sieve
  and retained on 10 mm sieve is filled in the
  cylindrical measure in 3 layers by tamping each
  layer by 25 blows. Determine the net weight of
  aggregate in the measure(W1)
• 2. Sample is transferred from the measure to
  the cup of aggregate impact testing machine and
  compacted by tamping 25 times
• The hammer is raised to height of 38 cm above the
  upper surface of the aggregates in the cup and is
  allowed to fall freely on the specimen.
• After subjecting the test specimen to 15 blows,
  the crushed
• aggregate is sieved through IS 2.36 mm
  sieve
• 5. Weigh the fraction passing through IS 2.36
  mm sieve(w2)
• Aggregate impact value w2/w1100
• w2 Weight of fines passing 2.36 mm
• w1 Weight of sample
  
• 7. Mean of the two values reported.

Test Set-up
125
(No Transcript)
126
(No Transcript)
127
4. Los Angeles Abrasion Test

• Significance
• It is resistance to wear or hardness of
  aggregates
• Road aggregates at the top subjected to wearing
  action
• Under traffic loads abrasion/attrition action
  within the layers as well
• To determine suitability, tests have to be
  carried out

• Procedure
• 1. Aggregates dried in oven at 105 -110C to
  constant weight conforming to any one of the
  gradings
• E.g. 1250 gm of 40-25 mm, 1250 gm of 25-20
  mm, 1250 gm of 20-12.5 mm, 1250 gm of 12.5-10 mm,
  with 12 steel balls
• 2. Aggregate weighing 5 kg or 10 kg is placed
  in cylinder of the machine(W1gms)
• Machine is rotated at 30-33 rpm for 500
  revolutions
• Machine is stopped and complete material is taken
  
• out including dust.
• 5. Sieved through 1.7 mm sieve
• 6. Weight passing is determined by washing the
  portion retained, oven drying and weighing (W2
  gms)
• 7. Aggregate abrasion value is determined
• A.A.V. W2/W1100
• W2 Weight of fines passing 1.7 mm, W1
  Weight of the sample

Test Set-up
128

• Discussion
• Select a grading close to the project for
  testing
• Simulate both abrasion and impact due to wheel
  loads
• It determines the hardness of the stone

129
5. Shape Tests on Aggregates
a. Flakiness Index b. Elongation Index c.
Angularity Number

• Significance
• Shape of crushed aggregates determined by the
  percentage of flaky and elongated particles
• Shape of gravel determined by its angularity
  number
• Flaky and elongated aggregate particles tend to
  break under heavy traffic loads
• Rounded aggregates preferred in cement concrete
  pavements as more workability at less water
  cement ratio
• Angular shape preferred for granular
  courses/flexible pavement layers due to better
  interlocking and hence more stability

130
Procedure (Flakiness Index) Flakiness Index The
flakiness index of aggregates is the percentage
by weight of particles whose least dimension is
less than three-fifths (0.6) of their mean
dimension. Applicable to sizesgt 6.3 mm.
1.The sample is sieved through IS sieve sizes 63,
50, 40, 31.5, 25, 20, 16, 12.5, 10 and
6.3 mm 2. Minimum 200 pieces of each fraction
to be tested are taken and weighed (W1 gm) 3.
Separate the flaky material by using the standard
thickness gauge. 4. The amount of flaky
material is weighed to an accuracy of 0.1 percent
of the test sample
5. If W1,W2,W3,. are the total weights of
each size of aggregates taken and
w1,w2,w3,.. are the weights of material
passing the different thickness gauges
then Flakiness Index
(w1w2w3.)100/(W1W2W3.) 100w/W
Where, W Total wt of material taken
in gms, w Total wt of material passing in gms
131
(No Transcript)
132
Elongation Index Elongation Index The
percentage by weight of particles whose greatest
dimension is greater than one and four fifth
times (1.8 times) their mean dimension.
Applicable to sizes gt6.3 mm. Procedure 1.
The sample is sieved through sieve sizes, 50, 40,
25, 20, 16, 12.5, 10 and 6.3 2. Minimum 200
pieces of each fraction to be tested are taken
and weighed (W1gm) 3. Separate the elongated
material by using the standard length gauge
4. The amount of elongated material is weighed to
an accuracy of 0.1 percent of the test
sample 5. If W1,W2,W3,. are the total weights
of each size of aggregates taken and
w1,w2,w3,.. are the weights of material
retained on the different length gauge slots
then Elongation Index (w1w2w3.)100/
(W1W2W3.) 100w/W percent
Where, W Total wt of material taken in
gms w Total wt of material retained in gms
133
(No Transcript)
134
(No Transcript)
135
Angularity number
The angularity number measures the percent voids
in excess of 33 percent which is obtained in the
case of the most rounded gravel particles. Ranges
from 0-11 (rounded gravel-crushed angular).

• The cylinder is calibrated by determining the
  weight of
• water at 27oC required to fill it
• 2. Aggregate is sieved through 20, 16, 12.5,
  10,6.3 and 4.75 mm IS sieves
• 3. About 10 kg of the predominant size should be
  available.
• 4. The sample of single-size aggregate is dried
  in an oven at 100oC to 110oC for 24 hours and
  then cooled
• 5. The scoop is filled with aggregate which is
  allowed to slide gently into the cylinder from
  the lowest possible height
• 6. The aggregate is filled in three layers,
  tamping each layer evenly 100 times with a
  tamping rod
• 7. After the third layer is tamped, the
  aggregates are struck off level with the help of
  tamping rod and surface finished
• 8. The aggregate with cylinder is now weighed to
  the nearest 5 g. The mean weight of aggregate is
  found.

136
Calculations and Observation Sheet Angularity
number 67-100W/CG where, W mean weight of
aggregates in the cylinder, C Weight of water
required to fill the cylinder, G Specific
gravity of aggregate

• Discussion
• Elongated, flaky and angular materials
  decreases the workability of the mix, and
• not preferred in cement concrete.
• Angular aggregates are preferred in flexible
  pavement at WBM/WMM
• Angularity number ranges from zero for
  perfectly rounded aggregate (rounded
• pebbles) to about 11 percent for freshly
  crushed aggregates
• But for DBM BC mix design may be modified to
  incorporate high angularity
• number.

137
(No Transcript)
138
THANK YOU
139
Flakiness Index Test IS 2386 part 1 Thickness
of flaky material is less than 0.6 times mean
size
IS sieves 63,50,40,31.5,25,20,16,12.5,10 and
6.3mm
140
Elongation gauge
141
Aggregate Impact test IS 2386 part 4 material
passing 12.5 mm sieve and retained on 10 mm sieve
is placed in mould in 3 layers by tamping 25
times for each layer. After 15 blows, material
passing 2.36 mm sieve is weighed and compared
with sample weight in .
142
200ml
In a 250 ml cylinder pour damp sand duly shaking
upto 200 ml mark. Fill cylinder with water
sufficient to submerge sand fully and stir the
sand well It can be seen that sand surface is
below original level
y
Bulkage of sand100(200-y)/y


143
Silt content test Fill 200 ml jar up to 100 ml
level with sand. Pour water up to 150 ml level
and shake vigorously . Allow it for 3 hours Silt
content h/H ? 100
144
Vicat Apparatus Plunger for consistency If
penetration is 5 to 7 mm from bottom of mould
(40mm), water added is of correct quantity for
standard consistency. 1 mm square needle for IST
Initial setting time is time between addition of
water to cement and when the needle ceases to
penetrate completely (about 5 mm from bottom of
mould). Needle with annular collar Final setting
time after water is added to cement and when
needle makes an impression but not the collar on
cement mould.
145
Strength test on 70.6mm 13 cement mortar
cubes to determine the grade of cement sand
shall be as per IS650
Grade number is 28 days compressive strength
in Mpa or N/mm2 1Mpa10.21 Kg/cm2
146
3 specimens of 150 mm cubes from the same
concrete are to be tested for compressive
strength
Average value of 3 specimens represent a sample
result. If the results of 3 specimens show more
than 15 variation with average value, it be
ignored
147
(No Transcript)
148
Bricks Size, shape, free from cracks and sharp
square edges. Bricks shall not break when dropped
from 1m height, shall give ringing sound when
struck with each other and leave no impression
with finger nails Water absorption lt 20 Dry
bricks for 4 hours at 100 to 110º C, weigh,(W1)
immerse in water for 24 hours at 27 2º C and
weigh again(W2) WA (W1-W2) W1 ? 100
149
Compressive strength Grind the 2 long
faces, apply cement mortar, wrap with gunny bag
for 24 hours, immerse in water for 3days. Measure
the brick and place it in testing machine with
3mm plywood planks on top bottom