Annual Report,2009 - Directorate General of Mines Safety
Annual Report,2009 - Directorate General of Mines Safety
Annual Report,2009 - Directorate General of Mines Safety
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DGMS <strong>Annual</strong> <strong>Report</strong>, <strong>2009</strong><br />
upto 35 days. If shrinkage is allowed than bolt with<br />
grouted material will release the surface <strong>of</strong> the hole<br />
and will fall out from the hole.<br />
4 Calcium Oxide<br />
Calcium Oxide exchange the cementing properties <strong>of</strong><br />
the grouting material and present in the quick set<br />
cement and other cements used in the manufacturing<br />
<strong>of</strong> the cement capsules. The optimum quantity <strong>of</strong> CaO<br />
is essential for getting the proper setting time as well<br />
as strength in the grouting material. Optimum quantity<br />
<strong>of</strong> CaO is 35%. Below the optimum it will affect the<br />
setting time and strength <strong>of</strong> the grouting material and<br />
above the optimum percentage brittle nature will<br />
develop in the grouting material. Cracks develops in<br />
the grouted material will release the bolt and become<br />
unsafe to mine environment.<br />
5. Alumina<br />
Alumina plays an important and crucial role in the<br />
initial setting, final setting and getting proper strength<br />
in the cement capsules. The quantity <strong>of</strong> alumina in the<br />
cement capsule is depends upon the quantity <strong>of</strong> high<br />
alumina cement added in the composition. <strong>General</strong>ly<br />
high alumina cement contain 35-45% alumina content<br />
and for manufacturing cement capsule <strong>of</strong> good quality<br />
and for manufacturing cement capsule <strong>of</strong> good quality<br />
about 30% high alumina cement should be added in<br />
the composition. Therefore, percentage <strong>of</strong> alumina<br />
percentage should not be less than 10% to get proper<br />
setting time as well as strength and shelf life <strong>of</strong> the<br />
grouting material. It was observed that above 25%<br />
alumina content in the cement capsules, the brittle<br />
nature <strong>of</strong> the grouted material is increased and cracks<br />
were developed in the material due to exothermic<br />
reacition.<br />
6. Iron Oxide<br />
Proper quantity <strong>of</strong> iron oxide in the cement capsules is<br />
required for getting proper performance and it should<br />
be not more than 5%. Above the optimum percentage<br />
iron oxide will enhance the brittle nature <strong>of</strong> the<br />
grouting material.<br />
7. Magnesium Oxide<br />
Optimum quantity <strong>of</strong> magnesium will give the better<br />
result but increase in percentage will decrease the<br />
setting time but increase the brittle nature <strong>of</strong> the<br />
material which may lead to decrease in the strength <strong>of</strong><br />
the material. MgO content.<br />
8. Loss on Ignition<br />
Organic and other combustible material should not be<br />
more than 2% <strong>of</strong> the total mass. It is observed that<br />
30 to 35%<br />
10 0 15%<br />
5% (Max.)<br />
2% (Max.)<br />
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