concrete deisgn

2. CONCRETE
 Concrete – is a common construction
materials, the properties of which may be
predetermined by design, selection of
constituent materials, and quality control.

3. •Strength
•Durability
•Modulus of Elasticity
•Shrinkage
•Creep
•Water tightness (impermeability)

4. • is the most important property of
hardened concrete.
• it is generally considered in the
design of most concrete mixes.
• it is affected by many variables,
including environmental factor and
curing conditions.

5. • The rate of hydration is not the same
for all types of cement.
•The strength of the concrete is also
dependent on the type, composition,
and fineness of cement.

6. • Several physical properties of
aggregates, and the amount used, affect
the properties of concrete both during
mixing and when hardened.
• The strength of concrete may also be
affected by the type and size of coarse
aggregate.

7. • Water-to-cement ratio is the ratio between the
weights of water and cement in a concrete mix.
• The compressive strength of concrete is
commonly estimated from the water-to-cement
ratio.

8. • Voids in concrete lower the durability, water
tightness, and compressive strength.
• Increase in the voids, diminishes the quality
of the concrete.

9. • Any excess in water in the mix – water
that does not participate in hydration hikes
the amount of voids.

10. • it should have a sufficient amount of cement,
well-graded aggregates, ample compaction and a
minimum mixing water.

11. The modulus of elasticity of concrete is a function
of the modulus of elasticity of the aggregates and
the cement matrix and their relative proportions.
The modulus of elasticity of concrete is relatively
constant at low stress levels but starts decreasing
at higher stress levels as matrix cracking develops.

12. •Shrinkage or volume reduction also called contraction is the
result of displacement of water from within to surface and the
loss of water to the surroundings.

13. •Plastic shrinkage or initial shrinkage is the decrease in
volume of the cement –water system while the
concrete is still plastic.
• Plastic shrinkage cracks, visible mostly in horizontal
surfaces, happen usually around the time when the
water sheen disappears from the surface.

14. FACTORS AFFECTING THE AMOUNT OF
PLASTIC SHRINKAGE AND RESULTANT
CRACKING IN CONCRETE:
•Type of cement
•w/c ratio
•Quantity and size of coarse aggregate
•Consistency of the mix

15. •Stiffer mixes have lower initial shrinkage than more
fluid concrete
•Reduction in the temperature of the fresh mix
lessens the amount of plastic shrinkage.
Techniques to minimize plastic shrinkage cracks:
•Spraying the coarse aggregate pile with cold water
or using cold water for mixing may offset their
development.
•Any procedure that minimizes or eliminates
evaporation loss decreases plastic shrinkage cracks.

16. •Erection of sunshades and windbreaks
•Applying curing compound or by covering the
freshly placed concrete with wet burlap or plastic
sheets.
•Water reducing and air-entraining admixtures are
also helpful in reducing plastic shrinkage cracks.

17. • is a hexagonal pattern of surface cracks
emerging at an early age in concrete is
primarily due to improper finishing or curing.

18. • Drying shrinkage is the reduction in volume
from drying of hardened concrete and is
attributed to the loss of water from the cement
gel.
• Drying shrinkage is gradual and the rate of
shrinkage decreases with time.

19. • Drying shrinkage depends on number of
factors such as type and amount of cement,
mix proportions, size and shape of structure,
curing, environmental conditions and
reinforcement.
• The most important factor that affects
shrinkage is the amount of aggregate

20. •Decrease in the maximum size or quantity of coarse
aggregate increases the amount of drying shrinkage.
• Over abundance of sand is found to significantly increase
the shrinkage
• As the cement content increases the shrinkage increases.

21. • Shrinkage of normal-weight concrete is less than that of
comparable lightweight concrete.
• Decrease in humidity causes rapid moisture loss and
increases the shrinkage
• Increase in the mass of aggregates or decrease in the
quantity of paste diminished the shrinkage.

22. •Keeping the water per unit volume of concrete as
low as possible or by keeping the aggregate content
as high as possible.
•Curing lowers the shrinkage
•Use of water reducing admixtures decreases the
amount of shrinkage; retarding admixtures may give
rise to more shrinkage.

23. •The restraint provided by reinforcement decreases
the magnitude of shrinkage, but instead induces
tensile stresses in concrete, causing it to crack.
•Reinforcement does not prevent cracks from
occurring, it merely controls the location and width of
cracks resulting from both shrinkage and
temperature effect.

24. •Various parts of structure my shrink differently. The
differential shrinkage between various elements in a
building may lead to cracking.
•Differential drying shrinkage between the top and
bottom surface of a slab-on-grade may lead to curling or
warping.
•Finishing operation should be started only after the
bleed water has disappeared.
•Over sanded aggregates which required a high w/c
ratio to obtain a satisfactory workability, give rise to
more cracking.

25. •Contraction joints (dummy joints or control joints)
provide to accommodate movement from temperature
changes, drying shrinkage, and creep is meant to direct the
cracks to the location of the groove. Without these joints
the concrete member will crack in a random manner.

26. •Construction joints ( isolation joints or expansion joints)
are provided to separate a slab from other part of a
structure, such as beams and columns, to prevent bonding
and permit horizontal and vertical movement.

27. •Shrinkage-compensating or expansive cement concrete is
defined as expansive cement concrete that when properly
restrained by reinforcement will expand by an amount
equal to or slightly greater than the expected contraction
from the drying shrinkage.
• Type K cement is also in cement-based grouts, to offset
the volume changes resulting from shrinkage or to prevent
settlement in the bedding of machinery and in structural
underpinning applications. This special cement is prone to
aeration deterioration while in storage, reducing the
expansiveness.

28. •Creep is the term used to describe the
permanent movement or deformation of a
material in order to relieve stresses within the
material.
• Creep occurs under all types of loading:
compression, torsion, and tension.

29. • Concrete which is subjected to long-duration forces
is prone to creep.
• Creep increase with increase in w/c ratio or volume
of cement paste.
• The lower the amount of aggregate the higher the
creep.
• The lower the modulus of elasticity of the
aggregates, the lower the resistant offered to creep.

30. •Carbonation is the term for the reaction between the lime
in concrete and the carbon dioxide from air, yielding
calcium carbonate. This chemical reaction reduces
concrete quality and its ability to protect reinforcement
from corrosion, and results in additional shrinkage in the
carbonated region.
• Resistance to carbonation can be improved by using high
quality dense concrete.

31. •Is the capacity of concrete to resist deterioration from
weathering (environment).
•It normally refers to the duration or life span of trouble-free
performance.

32. •The cement paste structure is dense and of low
permeability
•Under exposed conditions it has entrained air resist free-
thaw cycles.
•It is made with graded aggregates that are strong and inert;
and
•The ingredients in the mix contain minimum impurities
such as alkalis, chloride, sulfate, and silt.

33. •Alkali-aggregate reaction
•Sulfate attack
•Freeze-thaw cycles
•Reinforcement corrosion

34. •Alkali-aggregate reaction happened because of the presence
of water certain compound, in some natural aggregates react
chemically with alkalis of Portland cement released during
hydration. This is followed by expansion or swelling of the
aggregate particles, causing cracks and promoting
disintegration of concrete.

35. •Existence of alkali-reactive components in aggregate
particles
•High alkali content in cement
•Presence of moisture

36. •The most direct solution to the problem of alkali-silica
reaction is the avoidance of aggregates containing
soluble silica.
The use of low-alkali cement whenever aggregates are
suspected of containing reactive silica can also prevent
this reaction
Mineral admixture which contains fair amount of finely
divide silica can minimize the reaction such as fly ash or
ground granulated blast-furnace slag.

37. •Sulfate in soil and seawater can react with free calcium
hydroxide and aluminates in cement gel to produce
compounds that have volume greater that initial volume.
This process is called sulfate attack that cause expansion
and cracking in concrete.

38. Sulfate attacks can be minimize by
•Using a cement that is low in tricalcium aluminate like Type V
and Type II cement.
•Using fly ash or other admixtures can react to lime liberated
during hydration and reduce the amount of calcium aluminate
hydrate.
•When there is a high temperature sulfate attack may not be a
major problem.
•.

39. •Is the process by which water that is stored in voids within
concrete expands from freezing temperature that causes cracks and
deterioration.
•Scaling is the process of deterioration that is form when water
was applied in the top surface of the concrete during floating or
trowelling, had bleed water worked into surface during finishing
operations and was floated too early or over-trowelled or is
exposed to deicers, the top thin mortar lay may flake off from
freeze-thaw effect.

40. Corrosion risk is higher for structure exposed to sea
water or deicing salts. Corrosion has emerged as the
single most prevalent factor causing deterioration of
reinforced and pre-stressed concrete structures all over
the world.
Corrosion affects the reinforcing steel by reducing
its effective cross-sectional area and also affects the
concrete. For the corrosion products occupy larger
volume than the original volume of steel, there by
generating enough the pressure to cause cracking and
spalling of concrete...

41. Mix proportioning refers to the method by which the
most economical combination of materials for the desired
quality- with respect to strength, durability and workability
or consistency is established.

42. The objective of concrete mix design is to determined the
proportion of ingredients to produce concrete that is workable
and durable, of required strength and of minimum cost. The
three parameters that form the basis of mix design are:
-workability
-strength and durability
-economy

43. The selection of ingredients is based on the
following principles:
• the mix should be workable
• as little cement as possible should be used
• coarse and fine aggregate should be proportioned to
achieve a dense mix
• as little water as possible to be used
• the nominal maximum size of aggregate should be as a
large as possible
• the water to cement ratio will determine the compressive
strength.

44. The trial mix design procedure is formulated to achieve the
mix that will satisfy the strength, durability, and workability
requirements of concrete as closely as possible. The
procedure can be summarize as follow:
1. Workability is determined for the type of work.
2. The maximum aggregate size is chosen based on the
requirements of the job.
3. Air content is determined from durability requirements.
4. The water cement ratio is selected to satisfy strength and
durability.
5. The amount of water and coarse aggregate are chosen based
on average workability.

45. •is a material other than water , aggregates cement
and fiber ,added to plastic concrete or mortar to
change one or more properties at the fresh or
hardened stages .
•Some admixture are added to modify the workability
characteristics hydration rate of fresh concrete ,
whereas others change the properties of concrete
both at the mixing and hardened stages.

47. • this admixtures are employed to successfully adjust the
properties of the concrete.

49. Type Description ASTM
standard
Application
A Water reducing admixtures C494 To improve the workability
of the concrete
B Retarding admixtures C494 To delay setting and
hardening
:hot weather concreting:
large structures
C Accelerating admixtures C494 To accelerate setting and
early strength development :
cold weather concreting
D Water reducing and
retarding admixtures
C494 Similar to those for type A
and B
E Water- reducing and
accelerating admixtures
C494 Similar to those for types A
and C
F Water – Reducing admixtures
C494 In high- strength concrete :
to improve water tightness
and workability
G Water – reducing , high –
range and retarding
admixtures
c494 Similar to those types B
and F
H Air – entraining admixtures
, Antifreeze admixtures
C260 To improve durability and
workability : to minimize
freezing of water in fresh
concrete

50. • are added to concrete either to increase the rate of early
strength development or to shorten the time of setting, or
both.
• Chemical compositions of accelerators include some of
inorganic compounds such as soluble chlorides,
carbonates, silicates, fluosilicates, and some organic
compounds such as triethanolamine

51. PROBLEM ON APPLYING ACCELERATING
ADMIXTURE:
• The heat of hydration rises
•Corrosion of reinforcing steel and pre-stressing steel
is aggravated
• Shrinkage and creep

52. •Retarding admixtures (retarders) are known to delay
hydration of cement without affecting the long-term
mechanical properties.
•They are used in concrete to offset the effect of high
temperatures, which decrease setting times, or to avoid
complications when unavoidable delays between mixing and
placing occur .

53. PROBLEM:
• The maximum strength of the concrete takes a long
time to achieve.
• Cracks

54. •A method and composition for making concrete
includes an antifreeze admixed which is added to the
concrete to prevent the freezing of water in the concrete
when the concrete is cured during the winter or other
cold conditions

55. are groups of products that are added to concrete to
achieve certain workability (slump) at a lower w/c than
that of control concrete . Water-reducing admixtures
are used to improve the quality of concrete and to
obtain specified strength at lower cement content.

56. •less compressive strength when mixed to
type V cement “ only in type V cement”

57. •are used to stabilize microscopic air bubbles in concrete.
•Proper air-entrainment, with appropriate volume and
spacing factor, will dramatically improve the durability of
concrete exposed to moisture during cycles of freezing and
thawing. Entrained air also improves concrete’s resistance
to surface scaling caused by chemical deicers.

58. When mixed to high cement content it became
more sticky and hard to apply

59. Mineral admixtures (fly ash, silica fume [SF], and slags)
are usually added to concrete in larger amounts to
enhance the workability of fresh concrete; to improve
resistance of concrete to thermal cracking, alkali-
aggregate expansion, and sulfate attack; and to enable
a reduction in cement content

60. Type / class Description ASTM
standard
Application
N Raw or calcined natural pozzolan
C618 To improve durability and impermeability in
low – heat :application in hydraulic
structures :to improve sulfate resistance
and alkali – aggregate reaction
F Fly ash, bituminous coal origin
C618 To have high later age strength : low heat
cement , mass concrete , to improve sulfate
resistance and alkali – aggregate reaction
C Fly ash ,lignite or subbituminous
coal origin C618 Same with F
Silica fume In high strength concrete , to improve
water tightness in shortcrete

61. The most commonly used pozzolan in concrete, is a
finely divided residue that results from the
combustion of pulverized coal and is carried from
the combustion chamber of the furnace by exhaust
gases. Commercially available fly ash is a by-
product of thermal power generating stations.

62. •Fly ash F – low calcium content
•Fly ash C – more than 10 to 30 percent calcium
content compare to F

63. •Increase in ultimate strength
•Reduced temperature rise
•Reduced alkali – aggregate reaction
•Improved resistance to sulfate attack
•Reduced permeability
•Improved workability and pumpability
•Economy

64. •Water demand increases
•More air entraining admixture
•Slower strength development
•The color of the concrete may be affected

65. also known as microsilica, is a byproduct of the
reduction of high-purity quartz with coal in electric
furnaces in the production of silicon and ferrosilicon
alloys. Silica Fume is also collected as a byproduct
in the production of other silicon alloys such as
ferrochromium, ferromanganese, ferromagnesium,
and calcium silicon

66. • It is the mixture of fine aggregate,
coarse aggregate, water , cement and
sometimes it also contains admixtures

67. • Most ordinary concrete exhibits weaker
characteristics when subjected to tensile ,
flexural or shear force.

68. • To impart ductility to structures, ordinary
concrete is often used to form a composite
along with material that possess high-tensile
or flexural strength such as steel.

69. •
• REINFORCED CONCRETE
•PRE-STRESS AND PRECAST CONCRETE
•FIBER-REINFORCE CONCRETE
• LIGHTWEIGHT CONCRETE
• HIGH-STRENGTH AMD HIGH-PERFORMANCE
CONCRETE

70. • is concrete which steel reinforcement bars ,
plates or fiber has been incorporated to
strengthen a material that would otherwise be
brittle.

71. • Concrete is reinforce to give it extra tensile
strength, without reinforcement , may
concrete building would not have been
possible
•Much of the focus in reinforcing concrete is
placed on floor system

72. • is a structural composite material made
with ordinary concrete and high-strength
steel subjected to a pre-tensile force.

74. PRE-TENSION CONCRETE
• members are produce by stretching the pre-
stressing steel held between external anchorages
before the concrete .
POST-TENSION CONCRETE
a. Bonded Post-tension Concrete
• is a method of applying tension after pouring of
concrete.
• The concrete is cast around a plastic, steel or
aluminum curved duct, to follow the area where
otherwise tension would occur in the concrete
element.

75. b. Unbonded Post-tension Concrete
• differs from bonded post-tensioning by providing
each individual cable permanent freedom of
movement relative to the concrete. To achieve this,
each individual tendon is coated with a grease and
covered by a plastic sheathing formed in an
extrusion process. The transfer of tension to the
concrete is achieved by the steel cable acting
against steel anchors embedded in the perimeter
of the slab.

76. •Pre-stressed concrete is the predominant material
for floors in high-rise buildings.
• Due to its ability to be stressed and then de-
stressed, it can be used to temporarily repair a
damage building by holding up a damage wall or
floor until permanent repairs can be made.
• Enable pipes to handle high internal pressure and
the effects of external earth and traffic loads

77. • Controls cracks
• Lower Construction cost
• Lower maintenance cost over the design life of the
building

78. •is a form of construction, where concrete is
cast in a reusable mould or "form" which is
then cured in a controlled environment,
transported to the construction site and lifted
into place.
• Precast concrete products can withstand
the most extreme weather conditions and will
hold up for many decades of constant usage.

79. • Agricultural Products
• Building and Site Amenities
• Cemetery Products
• Hazardous Materials Containment
• Marine Products
•Transportation and traffic related products
• Water and Wastewater Products

80. •is concrete containing fibrous material which
increases its structural integrity
•It contains short discrete fibers that are uniformly
distributed and randomly oriented.

81. •Fibers are usually used in concrete to
control plastic shrinkage cracking and drying
shrinkage cracking.
• They also lower the permeability of
concrete and thus reduce bleeding of water.
•Improve resistance to explosive spalling in
case of a severe fire
•Improve impact resistance

82. •it is commonly used in tunnel lining, rock-slope
stabilization, pavement, slab-on-grade, wall
panels and floor slab.

83. • Light weight concrete is concrete with an air-
dried unit weight not exceeding 1850 kg/m³.
• All-lightweight Concrete- when both fine and
coarse aggregates are of lightweight type.
• Sand-lightweight Concrete- when regular
sand is used with lightweight coarse
aggregates.

84. • solves weight and durability problems in
buildings and exposed structures.
• offers design flexibility and substantial cost
savings.
• better thermal properties, better fire ratings,
reduced autogeneous shrinkage, excellent
freezing and thawing durability

85. • Floors in steel frame buildings.
• Concrete frame buildings & parking structures
• Bridge decks, piers & AASHTO girders
• Specified density concrete
• Lightweight concrete precast & prestressed
elements
• Marine structures, floating docks, ships, &
offshore oil platforms
• Fill concrete and insulating concrete

86. Pumice- is a light-colored glassy rock of finely
vesicular froth filled with elongated bubbles.
Scoria- is a coarsely vesicular glassy rock
containing more-or-less spherical bubbles

87. • Since they are very porous, absorb mixing
water, and may continue to absorb for several
weeks after construction.
• These aggregates tend to segregate and float
to the surface.

88. •
•it is necessary to wet these aggregates
before adding them to the mix.
•to prevent segregation , it may often be
necessary to limit the maximum slump or limit
the water content in the mix.

89. •A high-performance concrete is something more than is
achieved on a routine basis and involves a specification
that often requires the concrete to meet several criteria.
• High-strength concrete as concrete that has a specified
compressive strength for design of 6,000 psi (41 MPa) or
greater.
• A high-strength concrete is always a high-performance
concrete, but a high-performance concrete is not always
a high-strength concrete.

90. •Reduction in cross-sectional area of structural
elements, primarily columns in building and
bridge piers.
•Lower amount of reinforcing steel.
•Increased usable floor space.
•Low permeability and excellent durability.
•Decrease in dead loads on foundation.

91. •Low shear strength.
•Large amounts of creep and shrinkage due to higher
amounts of cement and lower amounts of aggregates
(in comparison to ordinary concrete)
•Low ductility or small failure strain, and brittle failure.
•Increased cost.

93. •is a fluid mixture of cement, lime, and
sand, used as a finishing material. It
should have the ability to adhere to a
substrate such as concrete, masonry, or
lath, and to itself.
• It is two primary functions are:
Appearance and Protection

94. •is a common type of plaster, used on wood or
masonry walls, which can be placed and
formed in variety of shapes , designs, and
textures.
THREE TYPES OF STUCCO
• Scratch coat
•Brown coat
•Finish coat

95. •Mortar is mixture of cement, lime, fine aggregate and
water
TWO TYPES OF MORTAR (MASONRY MORTAR)
• Lime mortar - mixture of sand, hydrated lime and
water
• Portland cement - lime mortar-is a mixture of
Portland cement, lime sand, and water

96. •Grout is a mixture of cement (or cement plus
lime), fine aggregate, pea gravel (or fine coarse
aggregate, generally 10mm. Maximum), and
water, with a consistency that allows for pouring
without segregation.
•The term “grout” is derive d from the Swedish
word groot , which means porridge.

97. •Shotcrete (also called gunite,
pneumatically applied mortar or concrete)
relates to mortar or concrete) relates to
mortar or concrete shot into placed using
compressed air.
TWO TYPES OF SHOTCRETE
• Dry mix process
• Wet mix process

98. •Cement-stabilized soil (also called soil
stabilization, cement-treated aggregates,
rammed earth, and soil cement) is produced
by mixing and compacting water, soil and
Portland cement.
•Soil cement can be described as a hardened
material formed by compacting soil, cement,
and water.

99. •This types of concrete, which is made with
little or no fine aggregates, is used for a type
of pavement that allows rainwater penetration.
•Cement bond particleboard is a panel material
manufactured with cement, wood fibers, and
very little water.