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 />
28 Days 16.0<br />
5 Anchorage Strength Minimum in Tonnes<br />
after<br />
30 Minutes 3.0<br />
2.8<br />
2 Hrs<br />
5.0<br />
3.5 Failed<br />
28 Hrs<br />
8.0<br />
(b) Chemical Properties<br />
Sl.<br />
No<br />
Parameters Acceptable Limit Result Conclusio<br />
n<br />
1 Thicksotropic/Viscosity Minimum – 35,000 39000 cps Passed<br />
cps & Maximum –<br />
50,000 cps<br />
2 Chloride Free Test No Chloride Chloride Failed<br />
Present<br />
3 Shrinkage Test @ 27 ± 20 0<br />
C & 65% Humidity<br />
24 Hrs<br />
Maximum 0.01%<br />
7 Days<br />
Maximum 0.01% No Failed<br />
35 Days<br />
Maximum 0.01% Shrinkage<br />
4 Chemical Constituents<br />
Loss on Ignition Maximum – 2% 7.0<br />
Calcium Oxide (CaO) Maximum – 35% 23.77<br />
Magnesium Oxide<br />
(MgO)<br />
Ferrous Oxide (Fe 2 O 3 ) Maximum – 2% 5.19<br />
Alumina (Al 2 O 3 )<br />
Silicon Dia Oxide<br />
(SiO 2 )<br />
Maximum – 5% 2.46<br />
10 to 25%<br />
Maximum 20%<br />
2.34<br />
32.00<br />
Failed<br />
Note :- It was also observed that the compressive strength had reduced by 25% when<br />
the casted cement blocks were immersed in water before subjecting compressive<br />
strength testing. Thus the above composition was found unsuitable for wet or watery<br />
strata conditions.<br />
On examination <strong>of</strong> the above information, it was found that the bare minimum<br />
anchorage load <strong>of</strong> 3 and 5 Tonnes required after 30 minutes and 2 hours could not be<br />
achieved. Even the required compressive strength <strong>of</strong> 16 MPa could not be achieved<br />
after 24 hours and also after 7 days. In addition, the composition had failed in other<br />
tests. Therefore the approvals granted to such manufactured were withdrawn.<br />
4.0 STANDARD PARAMETERS & CHEMICAL COMPOITION<br />
Based on the above observations, it was decided in this <strong>Directorate</strong> to have detailed<br />
discussions on this matter with the scientist from CIMFR who are dealing with this<br />
subject and also from the Expert on Strata Control and Rock Mechanics from Indian<br />
School <strong>of</strong> <strong>Mines</strong> University. After detailed deliberation on various issues and<br />
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