Quarrying OF Stones - Lecture notes 5 PDF

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Lecture Notes in Construction Materials QUARRYING OF STONES Quarrying Process The only operation involved in the production of natural stone. Quarry – the open part of the natural rock from which useful stone is obtained. Method of Quarrying Useful Materials Rocks suitable for the manufacture of stone materials. Mining The operations involved in obtaining minerals Excavation - voids formed Quarries - mined deposits

Excavating Stones buried in earth or under loose overburden are excavated with pick axes, crow bars, chisels, hammers, etc. Wedging This method of quarrying is suitable for costly, soft and stratified rocks such as sandstone, limestone, laterite, marble and slate. Heating Is most suitable for quarrying small, thin and regular blocks of stones from rocks, such as granite and gneiss. Blasting Explosives such as blasting powder, blasting cotton, dynamite and cordite are used. •

Boring (Jumper and Boring bar)

•

Charging

•

Tamping

•

Firing

Precautions in Blasting: 1. Blasting should not be carried out in late evening or early morning hours. 2.

The danger zone (area of about 200 m radius).

3. First aid should be available. 4.

The number of charges fired, exploded and the misfires should be recorded.

5.

Explosives should be stored and handled carefully.

6. Detonators and explosives should not be kept together. 7. Cartridges should be handled with rubber or polythene gloves. 8. A maximum of 10 bore holes is exploded at a time and that also successively and not simultaneously.

Quantity of Explosive Required 2

A=

L 0.008 Where:

A

= quantity of gunpowder or dynamite (g)

L = length of line of least resistance (m)...