Abrasion, Cavitation, Corrossion and Decomposition-Caused by Water

1. ABRASION ,ABRASION ,CAVITATIONCAVITATION,,
CORROSIONCORROSION , AND, AND
DECOMPOSITIONDECOMPOSITION
CAUSEDCAUSED BY WATERBY WATER

2. Presented By:Presented By:
Ali Bux WassanAli Bux Wassan
Department of MiningDepartment of Mining
Engineering, MUET, JamshoroEngineering, MUET, Jamshoro

3. AbrasionAbrasion
wherever the running water carries the tools of
erosion such as sand, become the source of
wearing away of the bedrock with the help of
those tools.
Abrasion involves loosening, disintegration,
rubbing and grinding action on rocks

5. CavitationCavitation
It is particularly observed, where running water
suddenly falls with high velocity, such as at
location from high level to low level
It is known that when stream velocity exceeds
12 m/sec, the water pressure developed result
in vertical sucking out of the material and
thereby creating holes and depression that
continue deepening with passage of time such
holes are called “potholes”.

7. Corrosion:Corrosion:
The slow but steady chemical action of the
stream water on the rocks is expressed by the
term “corrosion”
This depends mostly on the composition of
rock and also the composition of flowing
water.
The rocks which are not soluble in stream
water may be corroded highly.

9. DecompositionDecomposition
Movements of water brings about the dissolution of
certain materials in rocks.
This water may washout soft clays and other
decomposed materials from joints and faults.
It is the chemical action by which chemical
weathering or chemical alteration takes place.

10. Under varying humidity and alternate drying
and wetting conditions, some rocks separate
on their bedding planes, or in time,
disintegrate completely.
Alternate wetting and drying cause some
rocks to expand (swelling) and contact
(squeezing), thus affecting their properties.

11. One to the dissolution of minerals, the
hardness of water is enhanced, for
example, chemical alteration due to water
are;
1. If water consists of carbonic acid, it
dissolves limestone and dolomite by
removing calcium and magnese from the
rock

12. Chemical action of magnesium solution on
rocks is more intensive than sodium
chloride solution.
Rock formations consisting of gypsum, rock
salt, anhydrite are highly soluble minerals
and subject to a rapid process of alteration

13. Hydrochloride is an aqueous solution and is
a strong corrosion liquid acid and very
much soluble in water

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