Evaluation of Durability Indices for High

Performance Concrete

Mix Design as per ACI 211-1

Characteristic Compressive strength: 70 MPa

Design compressive Strength = 70 +10 = 80MPa

Due to the absence of test data for standard deviation, a marginal value of 10 MPa is added to obtain the design compressive strength

Sl. No. Material Specific gravity1. Cement 3.102. Fine aggregate 2.653. Coarse Aggregate 2.70

Super plasticizer: Conplast SP 430Specific gravity, Gsup Solids Dosage, s (%)1.18 40M sol=C X

d100

4.7 kg

V liq=M sol

G ¿X s9.95

l

m3

V w=V liqX G¿X100−s100

7.045l

m3

V sol=V liq−V w 3.0l

m3

1. Determination of water cement ratio

From the graph the average water cement ratio for 80 MPa concrete is chosen as 0.3.

2. Determination of water content

For a saturation point of 1.0 per cent the water dosage lies between 135 to 145 l/m3. Let us take as 140 l/m3.

3. Cement content

wc=0.3

c=1400.3

=466.66kg

Let us take cement content, c as 470 kg

4. Determination of coarse aggregate content

Since particle shape is not exactly known, to start with the coarse aggregate content is taken as 1075 kg/m3

5. Dosage of super plasticizer

A trail dosage of 1% is chosen to start with.

6. Volume of entrapped air

A volume of 1.5% is assumed for the entrapped air.

7. Calculations

M sol=C Xd100

=470 X 1100

=4.7 kg

V liq=M sol

G ¿X s= 4.7

1.18 X40100

=9.95 lm3

V w=V liqX G¿X100−s100

=9.95 X 1.18 X 100−40100

=7.045 l

m3

V sol=V liq−V w=9.95−7.045=2.905=3.0l

m3

Volumeof cement= 4703.10

=151.61=152 l

m3

Volumeof Coarse aggregate=10752.70

=398.14=400 l

m3

Volumeof entrapped air 1.5 X 10=15 l

m3

Total volume of ingridients excluding fineaggregates=volumeof water+volume of cement+volume of coarse aggregate+volumeof entrapped air+volume of superplasticizer=140+152+400+15+3=710 l

m3

Volumeof fineaggregate=total volume−toatal volume of ingridientsexcluding fineaggregate

VolumeofFine aggregate=1000−710=290 l

m3

SSDmassof sand=290 X 2.65=768.5 l

m3

Addingall the quantities∈col .3gives the density of concrete as2458.2 kgm3

8. Corrections

As the coarse aggregate is in dry condition, it will absorb certain amount of water from the mix.

Coarse aggregates absorb 1 % of water

M c=1075(1−1100

)=1064 kg

11 kg of water is to be added extra

Fine aggregates free surface moisture is 2%

M f=768.5(1+ 2100 )=783.4kg

14.9 kg of water is to be deducted

Super plasticizer adds 7.045 l of water

Net water correction = 11-14.9-7.045 = -13.945 = 11 l

Materials Cement (kg/m3)

1

Volume (l/m3)

2

Dosage SSD conditions (kg/m3)3

Water correction (l/m3)4

Composition 1 m3

5Water 140 140 140 - 129Cement@ w/c = 0.3

470 152 470 - 470

Coarse aggregate

1000 400 1075 +11.0 1064

Fine aggregate - 290 768.5 -14.9 783.4Air 1.5% 15 0Super Plasticizer 1.0% 3 4.7 -7.045 9.95

Total 710 2458.2 -11

Mix ratio is 470 : 784 : 1064 = 1: 1.66 : 2.26