Concrete Materials CIVL 3137 1 Concrete Ingredients Portland - - PowerPoint PPT Presentation

▶
concrete materials
SMART_READER_LITE
LIVE PREVIEW

Concrete Materials CIVL 3137 1 Concrete Ingredients Portland - - PowerPoint PPT Presentation

Jan 25, 2024 200 likes •535 views

Concrete Materials CIVL 3137 1 Concrete Ingredients Portland Cement Water Fine Aggregate Coarse Aggregate Supplementary Cementitious Materials Chemical Admixtures CIVL 3137 2 Important Aggregate Properties Crushing strength Deleterious

slide-1
SLIDE 1

Concrete Materials

CIVL 3137 1

slide-2
SLIDE 2

CIVL 3137 2

Concrete Ingredients

Fine Aggregate Coarse Aggregate Supplementary Cementitious Materials Water Portland Cement Chemical Admixtures

slide-3
SLIDE 3

CIVL 3137 3

Important Aggregate Properties

Hardness Soundness Shape and texture Relative density and absorption Gradation / Fineness Modulus Deleterious substances Crushing strength Chemical stability Dry-rodded unit weight

slide-4
SLIDE 4

CIVL 3137 4

Important Aggregate Properties

Hardness Soundness Shape and texture Relative density and absorption Gradation / Fineness Modulus Deleterious substances Crushing strength Chemical stability Dry-rodded unit weight

slide-5
SLIDE 5

CIVL 3137 5

Important Aggregate Properties

Hardness Soundness Shape and texture Relative density and absorption Gradation / Fineness Modulus Deleterious substances Crushing strength Chemical stability Dry-rodded unit weight

slide-6
SLIDE 6

CIVL 3137 7

Important Aggregate Properties

Hardness Soundness Shape and texture Relative density and absorption Gradation / Fineness Modulus Deleterious substances Crushing strength Chemical stability Dry-rodded unit weight

slide-7
SLIDE 7

Reactive Aggregate (ASR)

CIVL 3137 8

Map Cracking

slide-8
SLIDE 8

Alkali-Silica Reaction

Alkali‐silica reaction occurs when aggregates containing non‐crystalline (amorphous) silica react with alkali hydroxide in cement paste to form a gel that swells as it adsorbs water from the surrounding cement paste or the

  • environment. These gels can induce enough

expansive pressure to damage the concrete.

CIVL 3137 9

https://www.cement.org/learn/concrete-technology/durability/alkali-aggregate-reaction

slide-9
SLIDE 9

What is ASR?

CIVL 3137 10

Na+ Na+ Na+ K+ K+ K+ Ca++ Ca++ OH– OH– OH–

slide-10
SLIDE 10

What is ASR?

CIVL 3137 11

Na+ Na+ Na+ K+ K+ K+ Ca++ Ca++ OH– OH– OH–

Hydroxyl ions are attracted to the reactive silica

slide-11
SLIDE 11

What is ASR?

CIVL 3137 12

Na+ Na+ Na+ K+ K+ K+ Ca++ Ca++

C-N-S-H and C-K-S-H gel forms from alkali in the cement

slide-12
SLIDE 12

What is ASR?

CIVL 3137 13

H2O H2O H2O Ca++ Ca++ H2O H2O

C-N-S-H and C-K-S-H gel attracts water

slide-13
SLIDE 13

Alkali-Silica Reaction

Alkali‐silica reaction can be controlled using certain supplementary cementitious materials. In the proper proportions, silica fume, fly ash, and ground granulated blast‐furnace slag can significantly reduce or eliminate expansion due to alkali‐silica reactivity. Lithium compounds have also been used to reduce ASR.

CIVL 3137 14

https://www.cement.org/learn/concrete-technology/durability/alkali-aggregate-reaction

slide-14
SLIDE 14

CIVL 3137 16

Important Aggregate Properties

Hardness Soundness Shape and texture Relative density and absorption Gradation / Fineness Modulus Deleterious substances Crushing strength Chemical stability Dry-rodded unit weight

slide-15
SLIDE 15

CIVL 3137 17

Coarse Aggregate

TDOT Specs for Concrete Coarse Aggregate

Application Size No. Concrete Pavement 467 Concrete Base Course 467 Cement Treated Base Course 57 Structural Concrete 57 Prestressed Concrete 57 or 67 Precast Concrete 57 or 67

slide-16
SLIDE 16

CIVL 3137 18

Coarse Aggregate

TDOT Specs for Concrete Coarse Aggregate

Application Size No. Concrete Pavement 467 Concrete Base Course 467 Cement Treated Base Course 57 Structural Concrete 57 Prestressed Concrete 57 or 67 Precast Concrete 57 or 67

NMAS 2" 2" 1½" 1½" 1½" or 1" 1½" or 1"

slide-17
SLIDE 17

CIVL 3137 19

Coarse Aggregate

 narrowest dimension NMAS 5  depth of slab NMAS 3   3 NMAS clear space 4

slide-18
SLIDE 18

CIVL 3137 20

Coarse Aggregate

 depth of slab NMAS 3

d d d

slide-19
SLIDE 19

CIVL 3137 21

Coarse Aggregate

 narrowest dimension NMAS 5

d d d d d

slide-20
SLIDE 20

CIVL 3137 22

Coarse Aggregate

  3 NMAS clear space 4

clear space between rebars clear space (concrete cover)

rebar

slide-21
SLIDE 21

Source: Design and Control of Concrete Mixtures (PCA, 2007)

Fine Aggregate

slide-22
SLIDE 22

CIVL 3137 27

ASTM C-33 Sand

20 40 60 80 100 0.01 0.1 1 10 100 Opening Size (mm) Percent Passing .

1½" ¾"

3/ 8"

4 8 16 30 50 100 200

Coarse Sand Fine Sand

slide-23
SLIDE 23

CIVL 3137 28

Fineness Modulus

Fineness modulus (n.) an index of the coarseness or fineness of an aggregate; it is computed as the sum of the fraction retained on each full series sieve starting from the No. 100 sieve.

slide-24
SLIDE 24

CIVL 3137 30

Sieve Designation Cumulative Weight Retained (g) Cumulative Percent Retained (%) Cumulative Percent Passing (%) 1/2 in. 100 3/8 in. 100

  • No. 4

100

  • No. 8

99.0 10 90

  • No. 16

317.4 32 68

  • No. 30

575.4 58 42

  • No. 50

793.6 80 20

  • No. 100

932.5 94 6

  • No. 200

972.2 98 2 Pan 992.5 100

Fineness Modulus Example

= 274%  FM = 2.74

slide-25
SLIDE 25

Fineness Modulus

So what is the fineness modulus trying to tell us? If you plot the gradation curve, the percent retained is the length of a line drawn from the curve to the top

  • f the plot. Since we only use full series sieves, the

data points are equally spaced along the opening size

  • axis. If you assign a relative width of one to each

line, the fineness modulus is really an approximation

  • f the area above the gradation curve. The greater

the area, the coarser the sand.

CIVL 3137 31

slide-26
SLIDE 26

CIVL 3137 32

Fineness Modulus

20 40 60 80 100 0.01 0.1 1 10 100 Opening Size (mm) Percent Passing .

1½" ¾"

3/ 8"

4 8 16 30 50 100 200

      

94 80 58 32 10 FM

  • 2. 74

100

slide-27
SLIDE 27

CIVL 3137 33

Fineness Modulus

20 40 60 80 100 0.01 0.1 1 10 100 Opening Size (mm) Percent Passing .

1½" ¾"

3/ 8"

4 8 16 30 50 100 200

      

94 80 58 32 10 FM

  • 2. 74

100

slide-28
SLIDE 28

CIVL 3137 34

Fineness Modulus

20 40 60 80 100 0.01 0.1 1 10 100 Opening Size (mm) Percent Passing .

1½" ¾"

3/ 8"

4 8 16 30 50 100 200

FM

FM

  • 2. 74
slide-29
SLIDE 29

Fineness Modulus

If we examine the ASTM specification for concrete sand, the lower bound of the gradation specification represents the coarsest possible sand you could use and the upper bound of the specification represents the finest possible sand. The fineness moduli of those two gradations are 3.45 and 2.15, respectively. So, despite the name, fineness modulus is an index measurement of the coarseness

  • f the sand!

CIVL 3137 35

slide-30
SLIDE 30

CIVL 3137 36

ASTM C-33 Sand

20 40 60 80 100 0.01 0.1 1 10 100 Opening Size (mm) Percent Passing .

1½" ¾"

3/ 8"

4 8 16 30 50 100 200

Coarse Sand Fine Sand

slide-31
SLIDE 31

CIVL 3137 37

ASTM C-33 Coarse Sand

20 40 60 80 100 0.01 0.1 1 10 100 Opening Size (mm) Percent Passing .

1½" ¾"

3/ 8"

4 8 16 30 50 100 200

FM

  • 3. 45

Coarse Sand

slide-32
SLIDE 32

CIVL 3137 38

ASTM C-33 Fine Sand

20 40 60 80 100 0.01 0.1 1 10 100 Opening Size (mm) Percent Passing .

1½" ¾"

3/ 8"

4 8 16 30 50 100 200

Fine Sand

FM

  • 2. 15