22 VQto allow a close fit with adjacent stones. A cobblestone is oval in shape, and its face should
be larger in area than the bed. Size of cobblestones is the same as the of cut cobblestones.- Underground structures and bridges are built of slabs and stones form igneous and
sedimentary rocks, tunnels and above-water parts of bridges are built of granite, diorite,
gabbro, diabase and basalt with compressive strengths not less than 100 MPa. Facing
slabs from solid limestone or sandstone should feature a compressive strength of not less
than 60 MPa. Face stones and facing slabs for tunnels and bridges are given as “ rock”
face, grooved or fluted finishes. Sizes and shapes of slabs and stones are specified by
designs. - Hydraulic structures are generally built with natural stones or regular or irregular shape
(hewn, rolled, cut, sawn, and also crushed stone) from igneous, metamorphic or
sedimentary rocks. The stones should not be weathered or have any interlayers of soft
rocks (such as clay, gypsum and other readily soaking or soluble inclusions) or porous
shells and visible stratifications and cracks. - Crushed stone and sand is used for preparing mortars and concretes, for making road-
beds and drainage constructions.
iigsi
l. What are rock forming minerals? Give a brief account of the physical properties of the
felspar, pyroxene, mica and gypsum group of minerals.- What is a mineral? What are their physical properties?
- What is meant by ‘hardness of a mineral’? How can it be determined? What is Mohs scale
of hardness? - Give the physical properties of the following minerals: garnet, olivine, felspar, mica and
orthoclase. - Write short notes on the following:
(a) Lustre (b) Cleavage
(c) Hardness (d) Streak - Discuss the three important types of rocks and their formations.
- What is meant by rock-cycle? How does it represent the sequence of formation of the three
important types of rocks? - Give a brief account of the mode of origin and consolidation of igneous magma. How are
igneous rocks classified? - Discuss the formation, mode of occurrence and engineering utility of sedimentary rocks.
- Describe the important characteristic features and uses of the followings rocks:
Granite, Syenite, basalt, sandstone, marble, gneiss. - Write short notes on the following, giving their uses in the civil engineering works:
Granite, sand stone, marble, shale, dolerite. - State what do you know about formation, mode of occurrence and engineering utility of
sedimentary rocks. What types of them are most common? - Name the three geological classes into which rocks can be divided. Describe the process of
their formation. What are the important building stones which are derived from these
rocks?