The index of Pozzolanic Activity of the cements

Definition:

The pozzolanic activity index is a ratio between the value of the compressive strength of a mortar containing proportions of natural pozzolana of 28 days and a control mortar of the ordinary quality of the same age.

The purpose of the test:

this test consists in determining the activity index by the laboratory preparation both mortars in order to perform a real analysis of the results.

Methodology of work :

I-first part of the test:

Means necessary:

Standardized sand.
CPA artificial Portland cement.
Water mixing.
Calsinic vase.

Standard molds 4x4x16.
Mixer.
Ambient temperature of 20 ° C and relative humidity greater than or equal to 50%.
A shock device.

The mortar formulation N ° 01 (mortar witness):
Sand: 1350 g
Cement: 450 g
Water mixing: 225 g.

The formulation of the mortar N ° 02 (mortar with pouzolanic cement):

Cement: 337.5g
Calcinic Vase: 112.5g
Sand: 1350 g
Water: 225g
Fluidizing admixture: 0.2g

Mixing procedure:

operations Introduction of water Introduction of cement Introduction of sand Scraping of the tank
Duration of operation 30 sec 30sec 30 sec 15 sec 1min 15 sec 60 sec
Mixer Status Stop Speed Fast Stop Speed Fast

Filling of 3 test pieces for each type of mortar.
Shock molds to eliminate voids.
These test pieces must be kept for 28 days at a temperature of 20 ° C and a humidity level greater than or equal to 50%.

II-Second part of the test:
Means necessary:

A machine for the bending test.
A machine for the compression test.
The 06 specimens at 28 days old from the first part of this test.

II-a-Flexural procedure:
These 06 specimens will be subjected in the first place to bending forces to determine the bending strengths of mortars in a machine specialized in this type of test the results obtained are as follows:

II-b : Procédure de compression :
Apres soumettre les 6 éprouvettes à la flexion il vont être coupées en deux on obtient 12 demi éprouvettes ces dernier ms vont être soumises encor une fois à un effort de compression afin de déterminer leurs résistances à la compressions les résultats obtenues sont noté dans le trabeau ci-après.

Results of the tests:
Bending test:
Results of the 6 test pieces were subjected to flexion damage:
Witness mortar
EP1: F1 = 3.279 KN
EP2: F2 = 3.672 KN
EP3: F3 = 3.155 KN
Pouzolane mortar
EP4: F4 = 3.033 KN
EP5: F5 = 3.162 KN
EP6: F6 = 3.188 KN
Results of the 12 specimens subjected to the compressive force:
Witness mortar
F1 = 64,213
Ϭ1 = 40133
F2 = 61,783
Ϭ2 = 38614
F3 = 59816
Ϭ3 = 37385
F4 = 64,059
Ϭ4 = 40037
F5 = 55239
Ϭ5 = 34524
F6 = 66817
Ϭ6 = 41761
Pouzolane mortar
F7 = 51849
Ϭ7 = 32406
F8 = 49915
Ϭ8 = 31197
F9 = 52251
Ϭ9 = 32657
F10 = 47870
Ϭ10 = 29919
F11 = 47706
Ϭ11 = 29816
F12 = 43.386
Ϭ12 = 27116
Results analysis :
Flexion:
Mortar witnesses:
Ϭ = 1.5xFpxl / b3
Average Fp = 3.279 + 3.672 + 3.155 / 3 = 3.368KN
Ϭ = 1.5X3.368x1000x80 / 403 = 6.315 MPa
Mortar contains proportions of pozzolana:
Ϭ = 1.5xFpxl / b3
Average Fp = 3.033 + 3.162 + 3.118 / 3 = 3.104 KN
Ϭ = 1.5X3.104x1000x80 / 403 = 5.82 MPa
Compression:
Sample mortar:
Ϭmoy = (40,133 + 38,614 + 37,385 + 40,037 + 34,524 + 41,761) /6=38.742MPA
38.742-34.524 = 4.218 MPA
This value exceeds 10% of Ϭmoy so it must be removed and we resume the calculation with the other 5 values.
Ϭmoy = (40.133 + 38.614 + 37.385 + 40.03 + 41.761) / = 39.58 MPA
Mortar contains proportions of pozzolana:
Ϭmoy = (32.406 + 31.197 + 32.657 + 29.919 + 29.816 + 27.116) /6=30.52 MPA
30.52-27.116 = 3.404MPA
This value exceeds 10% of Ϭmoy so it must be removed and we resume the calculation with the other 5 values.
Ϭmoy = (32.406 + 31.197 + 32.657 + 29.919 + 29.816) /5=31.2 MPA
Caclul de I (puzolanic activity index)
I = 31.2 / 39.58 = 0.78 = 78%
Conclusion:
The pozzolanic activity index = 78%> 0.67 condition check for our case with pozzolanic proportions so our goal is reached at 100% and the theoretical conditions have been verified.

Nb: the photos were taken by myself.
PH01: Standardized sand
PH02 CPA cement
Ph03: calcine vase
ph04: Mixer
PH 05: Standard Mold 4x4x16
PH 06: Mortar in the molds
PH07: Bending and Compression Machine
PH08: pozzolanic mortar specimens
PH09: bending test
PH10: compression test

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