Friday, January 25, 2013

HPTSB- Diploma -2012- Civil Engineering materials -Question Paper

Hello there,
How you doing?

This  question paper was set by the Himachal Pradesh Takniki Shiksha Board, for the end semester examination Dec 2012 for the Subject of Civil Engg. -3rd semester.

I hope it helps you to prepare for your end semester examinations. Keep looking for the solution of the questions below the list of question paper.

Sub: Civil Engg. Materials                                         Semester : 3rd
Max Marks: 100                                                        Time: 3hrs.

Note: Attempt any five questions

Q.1 (a)Give the classification of the rocks. Give two numbers of examples of each.                  -10marks.
       (b) What are the requirements of a good brick earth.                                                        - -10marks.


Q.2  With a neat and clean sketch, explain the hoffman's kiln.                                                   -20marks.

Q.3 (a)Describe in brief the method of manufacturing of Portland cement.                                -10marks
        (b) Explain the burning of limestone.                                                                                  -10marks

Q.4 (a)Explain the decay of timber and its various causes.                                                        -10marks.
       (b) Explain the structure of the tree.                                                                                   -10marks.

Q.5 (a) Explain the varnishes, its composition and qualities.                                                       - 10 marks
       (b) What are the properties of asbestos?                                                                           -10 marks

Q.6 Explain any two of the following:
       (a) Low heat portland Cement.  (b) POP (c) Oilpaint (d) Plywood                                     -20marks

Q.7 (a) Explain the testing of the cement.                                                                                 -10marks.
        (b) Explain the defects of the timber.                                                                                -10marks.




  • Solutions:
  • Q.1

(a) 
The rocks are solid masses formed of the various minerals. The rocks form a large part of earth surface and crust. The rocks can be classified in three ways:
   (i) Geological classification
   (ii) Physical classification
    (iii) Chemical classification.

(i) Geological classification is based on the geology of the rock, their way of formation. According to the geology of the formation of the rocks they are classified in the three classes:
  (1) Igneous rocks   (2) Sedimentary rocks   (3) Metamorphic rocks.

(1) Igneous Rocks: Igneous rocks are formed by the solidification of the molten lava present in the crust of the earth. The rock minerals in the earth crust are in molten state due to very high temperature and whenever it gets the opportunity it erupts along a way to the earth surface.

 When it gets the low temperature on the earth surface or below the earth surface it solidifies to different rocks.
 Such rocks are known as the igneous rock. Some rocks are formed on the surface of the earth some are formed at a shallow depth from the earth and some at greater depth and accordingly they are classified into different categories i.e. Volcanic, Hypabyssal and Plutonic rocks.

The rocks formed below the surface of earth have crystalline structure and those formed on the surface of the earth are non crystalline. The example of plutonic rock is Granite, and example of a volcanic rock is Basalt.

(2) Sedimentary Rocks: Sedimentary rocks are formed due to the consolidation of the weathered rock particles. They are formed in the different layers of different matter. The heavier particle sediments settle early,and lighter are settled later, so these kind of rock are generally stratified. The example are the limestone and sandstone.

(3) Metamorphic Rocks: Metamorphic rocks are formed after the metamorphism of the igneous or sedimentary rocks. The rocks change their original properties under the external metamorphic agents like high temperature, pressure etc.

 The example are slate and marble, former obtained from shale and latter from the limestone. Gneiss is another example of it.

(ii) Physical Classification is based on the physical structure of the rocks. They can be classified as
     (1) Stratified Rocks  (2) Non-stratified rocks  and (3) Foliated rocks

(1) Stratified rocks are the rocks which are stratified into different layer and can be seen with naked eyes. The example are the sandstone and shale. Generally all the sedimentary rock are stratified.

(2) Non stratified rocks are the rocks which are stratified but generally a solid mass. All the igneous are generally non-stratified. example are granite and basalt.

(3) Foliated rocks are the rocks which can be separated along a specific direction only. Foliation takes place along a plane generally perpendicular to the direction of the principal stress. Example can be seen in many types of rocks. These rocks are formed after some pressure.

(iii) Chemical classification:
Chemically rocks are again classified into three categories. (1) Calcariious rocks (2)Sicious rocks (3) Argillacious Rocks.

Calcarious rocks are those rocks in which the calcium carbonate is the major mineral. Limestone is the best exapmple.
(2) Silisious rocks are the rocks in which the silica is the major constituent. The example is sandstone.
(3) Argillacious rocks are the rocks in which the alumina is the major constituent.

(Other solutions will be put soon.)

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Wednesday, January 23, 2013

Plywood

Plywood is a timber product, which is manufactured by many timber industries. It is made by gluing together 3 or more than 3 numbers of the veneer sheets. It is generally of 3mm or more than 3mm thickness. It is used to make the tables, chairs, beds, and many other furniture products.
Manufacturing Steps:  (1) Veneering (2) Gluing (3) Stacking (4) pressing/Loading (5)  Finishing

(1) Veneering: It is process of producing the veneer sheets from the timber logs. Veneer are the thin sheets, which are get by cutting the logs in a specific manner.
(2) Gluing: Veneer sheets are glued together, the number of sheets depends upon the required thickness. 
(3) Stacking :  The glued sheets are stacked in a specific manner to make them ready for the loading.
(4) Pressing/Loading: The glued sheets are pressed under a heavy pressure so then they are glued together with more strength. The application of load can be done at high temperature or it may be done at low temperature. Accordingly it is known as the hot pressing and cold pressing.
(5) Finishing is done by polishing the surface, with the required polishing material to give it a smooth and shining surface.

Plywood are provided with good surfacing and are make water  proof. They give a better appearance, so it is used in the decoration purposes.

Tuesday, January 22, 2013

Asbestos - Civil Engineering Material

Asbestos is considered a Civil Engineering material, because of its properties. It was used widely in the 19th century,  and it is used throughout the history. It was detected in the early 19th century in the England, and in many countries up to 1930. It was not banned up to 1970 in the USA, and court alleged the companies for not telling the truth about asbestos, which they knew since 1930. Many deaths were reported, due to inhaling of the asbestos fibers, which causes many diseases.
Properties and uses:
It is a fibrous material, having white & blue color.
It has the fire proofing, electric proof properties, so it was widely used for making the insulating boards, used in the building construction as a reinforcing material. It was also used to make fire proof dressing.
It has good tensile strength so it was used in the construction purposes, mixed with the cement it forms the asbestos  cement.
It has shining property, so it was used in the floors and the walls and ceilings too for the finishing.

Sources of the Asbestos(Producers): Russia,China, Kazakhstan, Brazil are the countries who has produced a remarkable amount of the asbestos till now. It was banned by the EU nations after knowing the hazards.
Health Hazards: 
There are six types of asbestos, having different minerals. The two major names, are Chrysotile and Amphibole. Chrysotile is the one which is mined today too, because it has less hazards properties. The use of the Amphibole is totally banned in Canada too because it stays in the lungs for much time when inhaled and can cause the cancer. The people who are prone to hazards with this material are the electricians, plumbers, masons, painters etc. It was widely used in the building construction before the 1970, so be careful to work with those buildings.

Garsa Stone -A Construction Material found in Kullu

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