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1
High Strength Concrete
CVLE 519
Concrete Technology
Dr. Adel El Kordi
Professor
Civil and Environmental
Engineering Depa...
2
A concrete that meets special combinations of
performances and uniformity requirements that cannot
always be achieved us...
3
• High-strength concrete has a compressive
strength greater than 40 MPa. In the UK, BS EN
206-1 defines High strength co...
4
• High-strength concrete is typically used in high-rise
structures. It has been used in components such as,
shear walls,...
5
Generally 28 days–compressive. Strength
6
This ultra high strength concrete specimen suffered
from a shear failure, where one small section
completely separated f...
7
shear failure
8
Time-dependent probability of concrete cover spalling in a typical reinforced
concrete bridge deck. (NC=normal-strength ...
9
Temperature distribution at various depths during fire exposure
in normal-strength concrete (NSC) and high-strength conc...
10
Punching Shear Resistance of High-Strength
Concrete Slabs
11
Punching Shear Resistance of High-Strength
Concrete Slabs
12
types W/C Fc28,MPa notes
HSC with good
mobility
0.25~0.40 50.0~70.0
15~20cm slump
large amount of
cement
high-strength
...
13
High-Strength Concrete Materials
Cement
• Use cement yielding highest concrete strength at
extended ages (91-days)
• Ce...
14
It would be difficult to produce high-
strength concrete mixtures without
using chemical admixtures. A
common practice ...
15
Chemical admixtures
• All type of HRWR, Superplasticizers or PolyCarboxylates
can be used.
• Air-entraining admixtures ...
16
Aggregates
• Coarse aggregate: 9.5 - 12.5 mm (3/8 -
1/2 in.) nominal maximum size gives
optimum strength
• Combining si...
17
Supplementary Cementing Materials
• Finely divided mineral admixtures, consisting mainly of
fly ash, silica fume and sl...
18
Pozzolans, such as fly ash and silica fume, are
the most commonly used mineral admixtures in
high-strength concrete. Th...
19
Chemical Analysis of Fly Ash, Slag and Silica Fume
Class F
fly ash
Class C
fly ash
Ground
slag Silica fume
SiO2, % 52 3...
20
Properties of Fly Ash, Slag and Silica Fume
Class F
fly ash
Class C
fly ash
Ground
slag
Silica
fume
Loss on
ignition, %...
21
Quantity of
Fly ash, slag and Silica fume in Concrete
by Mass of Cementing Materials
Fly ash
15% to 40%Class C
15% to 2...
22
Silica fume slurry consists of approximately 50 percent silica
fume and 50 percent water, by mass. When first introduce...
23
Effects Of Supplementary Cementing Materials On
@Freshly Mixed Concrete
Reduced Increased No/Little Effect/Varies
Fly a...
24
Effects Of Supplementary Cementing Materials On
Hardened Concrete
Reduced Increased No/Little Effect/Varies
Fly ash Sla...
25
1- For high strength concrete, the indirect tensile
strength may be about 5 percent of the compressive
strength.
2- At ...
26
Mix Design Procedure:
Fig-1 :Relation between compressive strength and reference number
27
Fig-4: Relation between compressive strength and reference number
28
Fig-5: Relation between water-cement ratio and Reference Number
29
Table – 1: Aggregate cement ratio (by weight) required to give four degrees of
workability with different water –cement...
30
Example 1
Design a high strength concrete for use in the production of precast
prestressed concrete to suit the followi...
31
IS sieve size Percentage Passing
Coarse aggregate Fine aggregate
20mm 100 100
10mm 96 100
4.75mm 8 98
2.36mm - 80
1.18m...
32
Fig-6: Combining of Fine aggregates and Coarse aggregates
33
DESIGN OF MIX
Mean strength = (50 / 0.80) = 63 MPa
Reference number (fig.1)= 25
Water cement ratio (fig 5) = 0.35
For a...
34
F=50MPa
Control factor = 0.8
Workability = very low
N.M.S = 10mm
sand crusted stone
GS 2.6 2.5
Moisture 5% 1%
Mean stre...
35
C/3.15x1000 + W/1000 + F/2.6x1000 + Cs /2.5x1000 = 1
C/3.15X1000 + 0.35C/1000 + 0.25X3.2C/2.6X1000 +
0.75X3.2C/2.5X1000...
36
Dry aggregate Moist aggregate
Cement 520 520
Water 182 182-21-13 = 148
Fine 416 416x1.05 = 437
Coarse 1250 1250X1.01 = ...
A high strength concrete mix proportions for one cubic meter and the
materials properties are as follows:
Assume air entra...
38
Air = 2%
• Unit weight = 550 + 165 + 600 + 1085 = 2400 kg/m3
•Yield =
• 50 15 54.55 98.64
•Y = 50/1000x3.15 + 15/1000 +...
39
•For 500m3 concrete
Mi x proportion
C w fine coarse
529 159 577 1042
V= 529/3.15x1000 + 0.159 +577/2.57x1000 + 1042/2.4...
40
Design a high strength concrete mix using. The 28-day characteristic cylinder
compressive strength is 600kg/cm2. The re...
41
W/C = 0.3
A/C = 2.7 (Fine =0.32, coarse = 0.68 )
Fine coarse
Gs 2.55 2.51
1.70 1.65
C/3.15 x 1000 + 0.3C /1000 + 2.7x0....
42
Y = 50/3.15x1000 + 0.15 + 43.17/1000x2.55 + 91.821/1000x2.51
= 0.0159 + 0.015 + 0.0169 + 0.0366 = 0.0844
Cement factor ...
43
44
@HIGH-EARLY-STRENGTH CONCRETE
• The time period in which a specified strength should be
achieved may range from a few h...
45
46
Applications for Fly ash and Slag Cement.
47
Synthetic fibers improve toughness and Plastic
Shrinkage of High Strength Concrete.
Synthetic fibers
48
Placing, Consolidating and Curing
1. Delays in delivery and placing must be eliminated
2. Consolidation very important ...
49
Curing
•Curing is the process of maintaining a satisfactory moisture content
and a favorable temperature in concrete du...
50
Precast concrete
Prestressed concrete
Precast - Prestressed concrete
Advantages of high strength concrete
51
Advantages of high strength concrete
2- Reduced initial construction costs
52
3- Wider girder spacing and longer spans
53
4- Significant savings in concrete quantities
54
5- Reduced long-term costs due to fewer repairs
55
6- Significant savings in construction depth
56
Strength-Weight ratio becomes comparable to steel
0
5
10
15
20
25
30
35
40
45
Structural steel Concrete High strength
c...
57
Example 3
The photographs given in Figures from 1 to 6 show different things related
to high strength concrete construc...
58
Figure 5
Figure 6
Figure 4
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2 high strength concrete

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2 high strength concrete

  1. 1. 1 High Strength Concrete CVLE 519 Concrete Technology Dr. Adel El Kordi Professor Civil and Environmental Engineering Department Faculty of Engineering
  2. 2. 2 A concrete that meets special combinations of performances and uniformity requirements that cannot always be achieved using conventional and normal mixing, placing and curing. High-strength concrete by definition is:
  3. 3. 3 • High-strength concrete has a compressive strength greater than 40 MPa. In the UK, BS EN 206-1 defines High strength concrete as concrete with a compressive strength class higher than C50/60. • High-strength concrete is made by lowering the water-cement (W/C) ratio to 0.35 or lower. Often silica fume is added to prevent the formation of free calcium hydroxide crystals in the cement matrix, which might reduce the strength at the cement-aggregate bond. High-strength concrete
  4. 4. 4 • High-strength concrete is typically used in high-rise structures. It has been used in components such as, shear walls, and foundations. High strengths are also occasionally used in bridge applications as well. A high-rise structure suitable for high-strength concrete use is considered to be a structure over 30 stories. • High –strength concrete is occasionally used in the construction of highway bridges. High-strength concrete permits reinforced or prestressed concrete girders to span greater lengths than normal strength concrete girders. Also, the greater individual girder capacities may enable a decrease in the number of girders required. Thus, an economical advantage is created for concrete producers in that concrete is promoted for use in a particular bridge project as opposed to steel. Applications of High-Strength Concrete
  5. 5. 5 Generally 28 days–compressive. Strength
  6. 6. 6 This ultra high strength concrete specimen suffered from a shear failure, where one small section completely separated from the rest
  7. 7. 7 shear failure
  8. 8. 8 Time-dependent probability of concrete cover spalling in a typical reinforced concrete bridge deck. (NC=normal-strength concrete; HPC=typical high performance concrete; HPC-IC=high performance concrete with internal curing.
  9. 9. 9 Temperature distribution at various depths during fire exposure in normal-strength concrete (NSC) and high-strength concrete (HSC) columns
  10. 10. 10 Punching Shear Resistance of High-Strength Concrete Slabs
  11. 11. 11 Punching Shear Resistance of High-Strength Concrete Slabs
  12. 12. 12 types W/C Fc28,MPa notes HSC with good mobility 0.25~0.40 50.0~70.0 15~20cm slump large amount of cement high-strength with normal consistency 0.35~0.45 55.0~80.0 5~10cm slump large amount of cement high-strength without slump 0.30~0.40 55.0~80.0 < 25mm slump normal amount of cement high-strength with low W/C 0.20~0.35 100.0~170.0 admixture RPC 0.05~0.20 70.0~240.0 70.0Mpa or above Classifications of High Strength Concrete
  13. 13. 13 High-Strength Concrete Materials Cement • Use cement yielding highest concrete strength at extended ages (91-days) • Cement should have min. 7-day mortar cube strength of 30 MPa • Cement contents between 400 and 550 kg/m3 • All types of cement are applicable. • To maintain a uniform high strength conrete: 1- Tricalcium silicate content varies by< 4% 2- Ignition loss varies by < 0.5% 3- Fineness varies by < 375 cm2/g (Blaine) 4- Sulphate (SO2) level should be maintained at optimum with variations limited to ± 0.20%.
  14. 14. 14 It would be difficult to produce high- strength concrete mixtures without using chemical admixtures. A common practice is to use a superplasticizer in combination with a water-reducing retarder. The superplasticizer gives the concrete adequate workability at low water- cement ratios, leading to concrete with greater strength. The water- reducing retarder slows the hydration of the cement and allows workers more time to place the concrete. Chemical admixtures
  15. 15. 15 Chemical admixtures • All type of HRWR, Superplasticizers or PolyCarboxylates can be used. • Air-entraining admixtures are not necessary or desirable in high-strength concrete as it decreases the value of the required compressive strength.
  16. 16. 16 Aggregates • Coarse aggregate: 9.5 - 12.5 mm (3/8 - 1/2 in.) nominal maximum size gives optimum strength • Combining single sizes for required grading allows for closer control and reduced variability in concrete • For 70 MPa and greater, the FM of the sand should be 2.8 – 3.2. (Lower may give lower strengths and sticky mixes)
  17. 17. 17 Supplementary Cementing Materials • Finely divided mineral admixtures, consisting mainly of fly ash, silica fume and slag cement have been widely used in high-strength concrete. • Dosage rate varies from 5% to 30% or higher by mass of cementing material depending on the type of mineral used . Fly ash (Class C ) - Metakaolin (calcined clay) - Silica fume - Fly ash (Class F) – Slag - Calcined shale (from left)
  18. 18. 18 Pozzolans, such as fly ash and silica fume, are the most commonly used mineral admixtures in high-strength concrete. These materials impart additional strength to the concrete by reacting with portland cement hydration products to create additional C-S-H gel, the part of the paste responsible for concrete strength. Pozzolans
  19. 19. 19 Chemical Analysis of Fly Ash, Slag and Silica Fume Class F fly ash Class C fly ash Ground slag Silica fume SiO2, % 52 35 35 90 Al2O3, % 23 18 12 0.4 Fe2O3, % 11 6 1 0.4 CaO, % 5 21 40 1.6 SO3, % 0.8 4.1 9 0.4 Na2O, % 1.0 5.8 0.3 0.5 K2O, % 2.0 0.7 0.4 2.2
  20. 20. 20 Properties of Fly Ash, Slag and Silica Fume Class F fly ash Class C fly ash Ground slag Silica fume Loss on ignition, % 2.8 0.5 1.0 3.0 Blaine fineness, m2/kg 420 420 400 20,000 Relative density 2.38 2.65 2.94 2.40 ASTM C 150 → L.O.I. ≤ 3% for O.P.C. Typical value = 1.4
  21. 21. 21 Quantity of Fly ash, slag and Silica fume in Concrete by Mass of Cementing Materials Fly ash 15% to 40%Class C 15% to 20%Class F 30% to 45%Slag 5% to 10%Silica fume
  22. 22. 22 Silica fume slurry consists of approximately 50 percent silica fume and 50 percent water, by mass. When first introduced to the market, slurried silica-fume products often contained water reducers or high-range water reducers. Today, slurry is available without any such additions.
  23. 23. 23 Effects Of Supplementary Cementing Materials On @Freshly Mixed Concrete Reduced Increased No/Little Effect/Varies Fly ash Slag Silica Fume Nat. Pozzolans Water Requirements Workability Bleeding & Segregation Air Content Heat Of Hydration Setting time Finishing Pump ability Plastic Shrinkage Cracking
  24. 24. 24 Effects Of Supplementary Cementing Materials On Hardened Concrete Reduced Increased No/Little Effect/Varies Fly ash Slag Silica Fume Nat. Pozzolans Strength Gain Abrasion Resistance Drying Shrinkage & Creep Permeability Alkali-Silica Reactivity Chemical Resistance Carbonation Concrete Color
  25. 25. 25 1- For high strength concrete, the indirect tensile strength may be about 5 percent of the compressive strength. 2- At low strengths, the indirect tensile strength may be as high as 10 percent of the compressive strength. Tensile splitting strength 3-The tensile splitting strength was about 8 percent higher for crushed-rock-aggregate concrete than for gravel- aggregate concrete. 4- The indirect tensile strength was about 70 percent of the flexural strength at 28 days.
  26. 26. 26 Mix Design Procedure: Fig-1 :Relation between compressive strength and reference number
  27. 27. 27 Fig-4: Relation between compressive strength and reference number
  28. 28. 28 Fig-5: Relation between water-cement ratio and Reference Number
  29. 29. 29 Table – 1: Aggregate cement ratio (by weight) required to give four degrees of workability with different water –cement ratios using ordinary Portland cement
  30. 30. 30 Example 1 Design a high strength concrete for use in the production of precast prestressed concrete to suit the following requirements: Specified 28-day works cube strength = 50 MPa Very good degree of control; control factor = 0.80 Degree of workability = very low Type of cement = ordinary Portland cement Type of coarse aggregate = crushed granite (angular) of maximum size 10mm. Type of fine aggregate = natural sand Specific gravity of sand = 2.60 Specific gravity of cement = 3.15 Specific gravity of coarse aggregates = 2.50 Fine and coarse aggregates contain 5 and 1 percent moisture respectively and have grading characteristics as detailed as follows:
  31. 31. 31 IS sieve size Percentage Passing Coarse aggregate Fine aggregate 20mm 100 100 10mm 96 100 4.75mm 8 98 2.36mm - 80 1.18mm - 65 600 micron - 50 300 micron 10 150 micron - 0
  32. 32. 32 Fig-6: Combining of Fine aggregates and Coarse aggregates
  33. 33. 33 DESIGN OF MIX Mean strength = (50 / 0.80) = 63 MPa Reference number (fig.1)= 25 Water cement ratio (fig 5) = 0.35 For a 10mm maximum size aggregate and very low workability, the aggregate- cement ratio for the desired workability (table-1) =3.2 The aggregates are combined by the graphical method as shown in figure 6, so that 30 percent of the material passes through the 4.75 mm IS sieve. Ratio of fine to total aggregate = 25% Required proportions by weight of dry materials: Cement – 1 Fine aggregates – [(25/100)x3.2] = 0.8 Coarse aggregates – [(75/100)x3.2)] = 2.4 Water = 0.35 If C = weight of cement required per cubic meter of concrete, then
  34. 34. 34 F=50MPa Control factor = 0.8 Workability = very low N.M.S = 10mm sand crusted stone GS 2.6 2.5 Moisture 5% 1% Mean strength = 50/0.8 =63 MPA R.N (fig1) = 25 W/c = 0.35 A/C = 3.2 (fine =0.25, coarse =0.75)
  35. 35. 35 C/3.15x1000 + W/1000 + F/2.6x1000 + Cs /2.5x1000 = 1 C/3.15X1000 + 0.35C/1000 + 0.25X3.2C/2.6X1000 + 0.75X3.2C/2.5X1000 = 1 (3.17 + 3.50 + 3.08 + 9.6) X 10-4C = 1 C = 104/19.35 = 520 KG W = 0.35 X 520 = 182 L Fine = 0.25 x 3.2 x 520 = 416 kg Coarse = 0.75 x 3.2 x 520 = 1250 Unit weight = 2368 kg
  36. 36. 36 Dry aggregate Moist aggregate Cement 520 520 Water 182 182-21-13 = 148 Fine 416 416x1.05 = 437 Coarse 1250 1250X1.01 = 1263 2368 2368 Batch Quantities per cubic meter of concrete
  37. 37. A high strength concrete mix proportions for one cubic meter and the materials properties are as follows: Assume air entrained = 2% Calculate: 1. The mix proportion as ratios to cement weight. 2. The unit weight of concrete. 3. The concrete yield. 4. The cement factor. 5. The amount of cement, sand and gravel required to produced 500 m3 of concrete. Coarse aggregateFine aggregateWaterCement 1085 2.43 1.59 600 2.57 1.65 165 1 -- 550 3.15 -- Weight by kg Specific gravity Unit weight t/m3 Example 2
  38. 38. 38 Air = 2% • Unit weight = 550 + 165 + 600 + 1085 = 2400 kg/m3 •Yield = • 50 15 54.55 98.64 •Y = 50/1000x3.15 + 15/1000 + 54.55/2.57x1000 + 98.64/2.43x1000 • = 0.0159 + 0.0150 +0.0212 + 0.0406 = 0.0927 •Y = 1.02 x y = 0.0946 m3 •Cement factor = 1/y = 10.57 bag. *c= 529kg Cement Water Fine Coarse kg 550 165 600 1085 Ratio 1 0.30 1.09 1.97 Bag of cement 50 15 54.55 98.64 ɣ kg/m3 1.65 1.59 Gs 3.15 1 2.57 2.43
  39. 39. 39 •For 500m3 concrete Mi x proportion C w fine coarse 529 159 577 1042 V= 529/3.15x1000 + 0.159 +577/2.57x1000 + 1042/2.43x1000 + 0.02 = 0.1679 + 0.1590 + 0.2245 + 0.4288 + 0.02 V= 1.002 m3 For 500 m3 of concrete C= 500x 529 = 264500 kg Fine = 500x 577 = 288500 kg/1.65 = 174.9 m3 Coarse = 500 x 1042 = 521000 kg/1.59 = 327.7 m3
  40. 40. 40 Design a high strength concrete mix using. The 28-day characteristic cylinder compressive strength is 600kg/cm2. The required slump is 200mm. The water/ cement ratio = 0.30 and the total aggregate /cement ratio = 2.70. The ratio of sand to all in aggregate = 0.32. The properties of aggregates are given in table below (N.M.S of coarse aggregate is 20 mm.). Calculate: 1. The concrete mix proportions. 2. The unit weight of concrete. 3. The concrete yield. 4. The cement factor. 5. Calculate the indirect tensile strength, and the flexure strength of concrete. 6. Adjust mix proportions, if the coarse aggregate can absorb 1.5% of its weight, and the fine aggregate has moisture of 0.50%. Coarse aggregateFine aggregate 2.51 1.65 2.55 1.70 Specific gravity Unit weight t/m3 Example 3
  41. 41. 41 W/C = 0.3 A/C = 2.7 (Fine =0.32, coarse = 0.68 ) Fine coarse Gs 2.55 2.51 1.70 1.65 C/3.15 x 1000 + 0.3C /1000 + 2.7x0.32c/1000x2.55 + 2.7x0.68 c/1000x2.51 =1 (3.175 + 3 + 3.388 + 7.315) x 10-4 c = 1 Concrete mix proportion : C = 1000/16.878 = 593 kg W = 0.30 x 593 = 178 kg Fine = 0.32 x 2.7 x 593 = 512 kg Coarse = 0.68 x 2.7 x 593 = 1089 kg Unit weight of concrete = 2372 kg/ m3 C W fine coarse 593 178 512 1089 50 15 43.17 91.82
  42. 42. 42 Y = 50/3.15x1000 + 0.15 + 43.17/1000x2.55 + 91.821/1000x2.51 = 0.0159 + 0.015 + 0.0169 + 0.0366 = 0.0844 Cement factor = 1/y = 11.85 bag Fc = 600 kg/ cm2 Ft = 5/100 x 600 = 30kg/ cm2 Ff = 30/0.7 = 43kg/cm2 Fine = 512 + 0.005 x 512 =512 + 3 = 515 kg (moisture ) Coarse = 1089 - 0.015 x 1089 = 1089 - 16 = 1073 kg W = 178 – 3 + 16 = 191 kg C W fine coarse 593 191 515 1073 Unit weight = 593 + 191 + 515 + 1073 = 2372 kg/ m3
  43. 43. 43
  44. 44. 44 @HIGH-EARLY-STRENGTH CONCRETE • The time period in which a specified strength should be achieved may range from a few hours to several days. • High-early-strength can be obtained by using one or a combination of the following: 1. Type III or HE high-early-strength cement. 2. High cement content 400 to 600 kg/m3. 3. Low water-cementing materials ratio (0.20 to 0.45). 4. Higher freshly mixed concrete temperature. 5. Higher curing temperature. 6. Chemical admixtures. 7. Silica fume (or other supplementary cementing materials). 8. Steam or autoclave curing. 9. Insulation to retain heat of hydration. 10. Special rapid hardening cements.
  45. 45. 45
  46. 46. 46 Applications for Fly ash and Slag Cement.
  47. 47. 47 Synthetic fibers improve toughness and Plastic Shrinkage of High Strength Concrete. Synthetic fibers
  48. 48. 48 Placing, Consolidating and Curing 1. Delays in delivery and placing must be eliminated 2. Consolidation very important to achieve strength 3. Slump generally 180 to 220 mm (7 to 9 in.) 4. Little if any bleeding—fog or curing agent have to be applied immediately after strike off to minimize plastic shrinkage and 7 days moist curing.
  49. 49. 49 Curing •Curing is the process of maintaining a satisfactory moisture content and a favorable temperature in concrete during the hydration period so that desired properties of the concrete can be developed. •Curing is essential in the production of quality concrete; it is critical to the production of high-strength concrete. •The potential strength and durability of concrete will be fully developed only if it is properly cured .
  50. 50. 50 Precast concrete Prestressed concrete Precast - Prestressed concrete Advantages of high strength concrete
  51. 51. 51 Advantages of high strength concrete 2- Reduced initial construction costs
  52. 52. 52 3- Wider girder spacing and longer spans
  53. 53. 53 4- Significant savings in concrete quantities
  54. 54. 54 5- Reduced long-term costs due to fewer repairs
  55. 55. 55 6- Significant savings in construction depth
  56. 56. 56 Strength-Weight ratio becomes comparable to steel 0 5 10 15 20 25 30 35 40 45 Structural steel Concrete High strength concrete Lightweight HSC Strength-Weight Ratio 7- Cost Saving %
  57. 57. 57 Example 3 The photographs given in Figures from 1 to 6 show different things related to high strength concrete construction. Discuss what you understand from each photograph. Figure2 Figure1 Figure3
  58. 58. 58 Figure 5 Figure 6 Figure 4

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