CE210IU Construction Materials 02

7/23/2019 CE210IU Construction Materials 02

1/7

1/22/2013

1

Department of Civil Engineering

International University - VNU HCMC

Mar. 15, 2012

CE214U-Constructions Materials

Concrete

Nguyen Dinh Hung Dr. Eng.

What is concrete? 1

Concrete is a composite construction material

composed primarily of aggregate, cement ,

waterand others (admixture) .

Aggregate: crushed stone, gravel, sand

Cement, water (bonding)

Admixture: Lime stone, fibers, fly ash, rice husk

slag, blast-furnace slag, gypsum, ice, silica

fume, glass,

Strong in compression

Week in tension

Easier in making shape

Introduction to the course 2

Cement and admixture

Portland Cement 3

A cement is a binder. (Portland) cement is

an instant glue (just add water) that bonds

aggregates together to make Portland cement

concrete.Particle size: Max. size: 0.09 mm

Min. size: 0.01mm

Size of smaller 0.045 (85-95%)

Properties of cement 4

The total surface area per unit weight: 2500 to 3000 cm2/g

Specific gravity of Portland cement : r c =3.05 to 3.15 g/cm3

Unit weight: g c =1.1 to 1.6 g/cm3 (measured by weight rather than volume)

Setting (time) refers to the stiffening of the cement paste or the change

from a plastic state to a solid state.

Initial set time and final set time determined by

Vicat apparatus

Initial set time: from the beginning until Vicat needle

penetrate in to cement past 25 mm (38-39 mm)

within 30 second (measure

every 15 minutes) : 45 minutes

Final set time: when the needledoes not penetrate visibly into

the paste (1 to 2 mm)

Strengths: compressive and

tensile strengths.

Diameter:50 mm, height: 100mm

Hydration of Portland cement 5

1: aggregate;2: Ca(OH)2

(20-25%);

3: C-S-H (50-60%);

4: Ettringite

(C-A-S-H)Spread heat


2/7

1/22/2013

2

Dimension of components 6 Types of cement 7

C3S (Belite):Main compound,

Determine higher strength and other properties,Hardens rapidly (4 weeks),Spread large amount of heat better for cold whether, treatment in hot whether

C2S (Alit):

Also main compound,Also determine medium strength and other properties,

Hardens slowly in beginning (after 1 weeks), after that quicker

Spread small amount of heat.

C3S and C2S: Contribute approximately equally to the ultimate strength.

C3A:

Hardens rapidly determine initial set

Contribute low strength,Spread small amount of heat

Easily be attacked by sulfate

Prevent by chloride attack,C4AF:

Reduce temperature in producing cement

Harden, contribute strength, spread

temperature and prevent chloride andsulfate moderate.

affect initial set and earlystrength

Types of cement 8 Strength development of cement types 9

Types of cement 10 Type of cement 11

Loss on ignitioninsoluble residue

Total alkali content Na2O+0.658K2O


3/7

1/22/2013

3

Blended hydraulic cement Portland cement 12

Blended cements are used in all aspects of concrete construction in the

same manner as Portland cements.

05 type of blended cements based on ASTM C 595

Type IS: Portland blast-furnace slag cement

Type IP and Type P : Portland-Pozzolancement

Type I(PM): Pozzoland-Modified Portland cement

Type S Slag cement

Type I(SM) Slag-modified Portland cement

Type IS: mixed by blast-furnace slag cement and Portland cement ingranulating or later from 25% to 75% (mass) for general concrete to

prevent:

Air-entrainment (added by suffixes A);

Moderate sulfate resistance (MS),

Moderate heat (good for large mass) (MH).

Blended hydraulic cement 13

Type IP and P: mixed by portlandcement and puzzoland (+blast-furnace

slag cement) in granulating or later from 15% to 45% :

Concrete with type IP cement is similar properties to type I portland

cement;

Type IP: air-entrainment (IP-A), moderate sulfate resistance (IP-

MS), moderate heat (IP-MH).

Type P: low heat (P-LH), moderate sulfate resi stance (P-MS), air-

entrainment (P-A),

Durability in water, it is used in water (wet) environment

High shrinkage and lower strength in air condition

Harden slower in normal condition, but quick in high temperature

Blended hydraulic cement 14

Type I(IM): mixed by portland cement, blast-furnace slag cement and

fine puzzoland of less than15% :

Air-entrainment (A),


moderate heat (MH).

Type S: mixed slag cement (large than 70%) to other cement types to

prevent air-entrainment

Type I(SM): mixed slag cement (less than 25%) to other cement types

to prevent:

Air-entrainment (A),


moderate heat (MH).

Hydraulic cement 15

ASTM C 1157 provides for six types of hydraulic cement as follows:

Type GU: General use

Type HE: High early strength (higher strengths at early age Type III)

Type MS: Moderate sulfate resistance (Type II)

Type HS: High sulfate resistance (Type V)

Type MH: Moderate heat of hydration (Type II)

Type LH: Low heat of hydration (Type IV)

Cementitious composite for self heal concrete

Admixtures Fly ash 16

Admixture: Lime stone, fibers, fly ash, rice husk slag, blast-furnace

slag, gypsum, ice, silica fume, glass:

Fly ash is a byproduct of the combustion of pulverized coal in thermal

power plants;

Compound: silicon, aluminum, iron, calcium, and magnesium;

Fly-ash particles: spherical and diameter from


4/7

1/22/2013

4

Admixtures Blast furnace slag 18

Blast-furnace slag is a byproduct of iron manufacture

Slow cooling of slag melts: unreactive crystalline material;

Rapidly cooled or quenched below 800 C: reactivity or hydraulicity slag as

cement,

Compound: CaO (30-50%), SiO2 (28-38%), Al2O3 (8-24%), and MgO (1-18%);

Admixtures Silica fume 19

Silica fume is a byproduct of iron manufacture of silicon or of various

silicon alloys produced in submerged electric-arc furnaces;

Silica fume particle: spherical and average diameter of 0.1 mm (cement 10mm)

Compound:

Types of fibers 20

Type PolypropylenePolyvinyl alcohol

(PVA)Steel Fiber

Shape 0.71.2, L30 0.66, L30 0.6, L30

Density (t/m3) 0.91 1.3 7.85

Price (yen/kg) 1290 1210 230

Tensile strength (MPa) 465 861 1000

Elastic modulus (GPa) 15 23 210

30mmPolypropylene 30mmSteel Fiber30mmPVA

Improve ductile of concrete

Reduce compressive strength

Admixtures affect on fresh cement 21

Admixture: Fly ash, blast-furnace slag, silica fume, fibers, lime stone, rice

husk slag, gypsum, ice, glass,

Admixtures affect harden cement 22

Fly ash, ground granulated blast-furnace slag, calcined clay, calcined

shale, and silica fume on the drying shrinkage and creep of concrete is

generally small and of little practical significance

Introduction to the course 23

Concrete


5/7

1/22/2013

5

Types of concrete 24

Based on unit weight:

L ight weight concrete:


6/7

1/22/2013

6

Properties of hardened concrete strengths 30

Compressive strength (fc) Young Modulus (Ec)

Sample casted by mould:

Diameter =10cm,

Height = 20cm

Tensile strength (ft)

Sample casted by mould:

Diameter =15cm,

Height = 30cm


Compressive strength (fc) Young Modulus (Ec)

Data logger

Young Modulus is

measured by Elastic

Modulus testing

apparatus with accuracy

of mm (10-6mm)

Or measured by

electric strain gauge


Compressive strength and Young Modulus (by elastic Modulusapparatus)

Step 1:Applied load until sample is totally crushed to determine peak load

Step 2:Applied elastic modulus apparatus and measure strain and load

from 0 (zero) up to larger 1/3 peak load ( a little) , then stop

Step 3: Take elastic

modulus apparatus out

Step 4: Test sample

until getting peak load

0.00

20.00

40.00

60.00

80.00

100.00

120.00

0 1000 2000 3000 4000 5000 6000 700050

1/3 P

Ec= P/d=tan

fc= P/A

P


Split tensile test

DL

Pft

p

2=

P: Peak load (N)

D,A, L: Diameter (mm), area (mm2)

and length (mm) of sample

d : displacement (mm)

0

s t

ft

e t

EcHordijks model (Hordijk, 1991)

Ec : Modulus of elasticity

ft

: Tensile strength

Tensile softening

curve

Properties of hardened concrete 34

2bd

Pl

I

McfR r ===

'63.0 cr ffR == (AASHTO)

Modulus of rupture (Flexural strength)

0 e0 ep ec

Ec

sc

fc Compressionsoftening curve

Secant modulus

Compression model for concrete

Calculating mix proportion of 1m3 concrete 35

Mix proportion of concrete: determine amount of compounds for concrete

such asAggregate, Sand; Cement; Water, admixtures to get harden

concrete with required properties.

Sep 1:

Sieve analysis of fine and coarse aggregate; fineness modulus

Dry unit weight of coarse aggregate (kg/m3)

Absorption capacity or free moisture in the aggregate (%)

Bulk specific gravity of materials ( kg/m3)

Step 2:

Slump and maximum size

of aggregate to select

water volume (W);

Recommendation slump for various type of construction

Type of constructionSlump (mm)

Max. Min.

Reinforced foundation and footing, plain

footing caissons and substructure walls76.2 25.4

Beams and reinforced walls 101.6 25.4

Building columns 101.6 25.4

Pavement and slabs 76.2 25.4

Mass concrete 50.8 25.4


7/7

1/22/2013

7

Calculating mix proportion of concrete 36 Calculating mix proportion of concrete 37

Sep 3:

Determine required compressive strength, (f

c normally specified strengthat 28 days) in order to determine water cement ratio (W/C)

Compressive strength of normal concrete depends mainly on W/C

From Step 2 and Step 3: Volume weight of water (W - in litter) and

cement (C in kg) can be determined

Calculating mix proportion of concrete 38

AA VA *r=

)( AWCBS ++-=Step 5:

Determine amount of sand (S)

Sep 4:

Determine amount of

aggregate (A)


)1()1()100(10 ---+-= aveC

ave

ave NCKB rr

r

r

Determine B based on below table or below equation

Where:

ave: average volume weight of aggregate and sand

C: volume weight of cement (3150 kg/m3)

K: air content in concrete (%)


Note:

Aggregate and sand are normally in wet condition, therefore weight of

aggregate and sand is weight larger and amount of water should be

reduced.

Volume of compound is normally not accuracy, therefore all compoundshould be added from 0.55 to 0.75 time.

After determining amount of compound, test samples will be

conducted, amount of compound will be control for concrete of realstructure.

Thank you for your kind attention!

Department of Civl Engineering

International University VNU HCMC

Documents

CE210IU Construction Materials 02