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সর্ব-শেষ হাল-নাগাদ: ২০ ফেব্রুয়ারি ২০১৯

পাথর সম্পর্কে

1
Introduction:
 

In recent time, considerable amount of construction activities are taking place in Bangladesh both in public and private sectors. Government is taking initiative to implement megaproject like Bridge, Metrorail, Sea Port, Tunnel under River, Nuclear Power Plant, upgradation of National Highway into four lanes etc. Aggregates are the major construction materials of these construction projects. Major part of the aggregates drive from igneous and metamorphic rock both local and foreign sources. Maddhapara Granite Mine, a govt. owner underground mine, is only source of igneous rock i.e granite aggregates in the country having production capacity 1.65 million Metric Tons per annum.

2 Igneous and Sedimentary Rock:
 

Rock is a natural substance composed of solid crystals of different minerals that have been fused together into a solid lump.  Igneous and Sedimentary Rock are the main source rock of aggregates.

 

 ‍a. Igneous Rock:
Igneous rocks are formed when magma (molten rock deep within the earth) cools and hardens. Sometimes the magma cools inside the earth, and other times it erupts onto the surface from volcanoes (in this case, it is called lava). About 64.7% of the Earth's crust by volume consists of igneous rocks; making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, and 17% granodiorites and diorites. Among the igneous rock, good properties of granite make it the most popular building material. It is the best aggregate for high-grade concrete.

 

b. Sedimentary Rock:
Sedimentary rocks are formed from particles of sand, shells, pebbles, and other fragments of material. Together, all these particles are called sediment. Gradually, the sediment transported through river/ stream and accumulates in layers and over a long period of time hardens into rock. Generally, sedimentary rock is fairly soft and may break apart or crumble easily. You can often see sand, pebbles, or stones in the rock, and it is usually the only type that contains fossils.

3 Sources of construction aggregates in Bangladesh:
 

Bangladesh is occupying most part of the Bengal Delta having very thick sedimentary cover. Main source of construction aggregates is sedimentary rock but government developed an underground mine (Maddhapara Granite Mine) for high quality aggregates from igneous rock. Unfortunately, the country fulfill their most demand from imported rock both igneous and sedimentary rock.    

     
                Local Source:    a. Maddhapara Granite Mine (Igneous Rock)
                                       b. Sylhet (Sedimentary Rock)
                                       c. Panchagar (Sedimentary Rock)


             Foreign Source :  a. India
                                       b. Bhutan
                                       c. Indonesia
                                       d. China

   

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