Topic: – Introduction of rocks || construction materials | Civil Engineering Hindi tutorials
By: – Munesh Sir
Email ID: – Wahthu.email@example.com
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The term ‘construction minerals’ is used to describe all minerals used by the construction industry, for example in road making, in concrete, in house construction and as railway ballast. The largest component of construction minerals and the most voluminous materials extracted from the UK landmass are ‘aggregates’ – a term used to describe granular or particulate material which is suitable for use on its own, or with a binder such as cement, lime or bitumen (in construction). Aggregates are used in concrete, mortar, roadstone or asphalt (drainage courses), or for constructional fill and railway ballast. The two principal types of natural aggregate are crushed rock (limestone, igneous rock and sandstone) and sand and gravel. In addition to land–won sand and gravel, significant quantities are produced by marine dredging. Other minerals used in the construction industry are clay, chalk, limestone, dolomite, brick clay, gypsum, slate and building stone.
Types of Rocks
Rocks are not all the same!
The three main types, or classes, of rock are sedimentary, metamorphic, and igneous and the differences among them have to do with how they are formed.
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 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.
Examples of this rock type include conglomerate and limestone.
Metamorphic rocks are formed under the surface of the earth from the metamorphosis (change) that occurs due to intense heat and pressure (squeezing). The rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by minerals growing slowly over time, on their surface.
Examples of this rock type include gneiss and marble.
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). When lava cools very quickly, no crystals form and the rock looks shiny and glasslike. Sometimes gas bubbles are trapped in the rock during the cooling process, leaving tiny holes and spaces in the rock.