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Bharathi Portland pozzolana cement is a premium composite cement manufactured by inter grinding of high quality clinker, carefully selected High reactive Silica (HRS) obtained from electrostatic precipitators with right quality gypsum.
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Hydration of blended cement:
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Ordinary Portland Cement + water ----- C-S-H GEL+ Ca(OH)2 (Alkali)
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This alkali is a byproduct in any OPC hydration process amounting to 25% of total gel formation.
This is like a weak link in strong chain. Sulphates and chlorides present in water, soil or surrounding atmosphere attacks this alkali causing deterioration of concrete. |
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Secondary gel formation in blended cement:
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High reactive silica(HRS) + alkali ------ Secondary gel formation
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The reactive silica which is added to the cement would react with the alkali and secondary gel formation takes place. As a result of this secondary gel formation pore refinement takes place and the concrete becomes more impermeable to sulphate and chloride attacks leading to the durability of concrete structures.
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Properties
a) Physical |
Requirements of IS1489(part1):1991 |
Bharathi cement values |
Competitors values |
| Fineness (sqm/kg) |
300 (min) |
350 |
300 |
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Soundness (mm) |
| Lechatlier method |
10mm (max) |
1 |
1.5 |
| Autoclave (%) |
0.8 (max) |
0.03 |
0.05 |
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Setting time |
| Initial (min) |
30 minutes |
165 |
260 |
| Final (max) |
600 minutes |
260 |
340 |
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Compressive strength (MPa) |
| 3 days (min) |
16 |
33 |
28 |
| 7 days (min) |
22 |
43 |
38 |
| 28days (min) |
33 |
63 |
50 |
| b) Chemical |
| Loss on ignition (%) |
5 (max) |
0.8 |
1.5 |
| Sulphuric anhydrideSO3 (%) |
3 (max) |
1.5 |
2.3 |
| Insoluble residue (%) |
X+4(100-X)/100 |
17 |
25 |
| Magnesia (%) |
6 (max) |
1 |
1.4 |
| Chloride (%) |
0.1 (max) |
0.002 |
0.02 |
| Temperature during Testing |
27±2 |
27±2 |
27±2 |
| Humidity (%) |
65±5 |
65±5 |
65±5 |
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Advantages of PPC Cement
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Low heat of hydration
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Resistance to sulphate attack and chloride attack
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Resistance to alkali silica reaction
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Reduction in water demand
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Reduced bleeding due to high fineness of cement
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Pore refinement leading to improved density of concrete
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