ইঞ্জিনিয়ারিং মেটেরিয়ালস MCQ
301. A first class brick when immersed in cold water for 24 hours should not absorb water more than- [BPSC-22]
10%
20%
15%
25%
ব্যাখ্যা: ব্যাখ্যা: A first class brick when immersed in cold 11 water for 24 hours, it absorb 1/5 to 1/7 (15% to 20%).
It should not absorb water more than 20%.
302. Which of the following is the purest form of iron? [BB-20]
Cast iron
Wrought iron
Mild steel
High carbon steel
ব্যাখ্যা: ব্যাখ্যা: Wrought iron is the purest from of iron. It contains 0.12 to 0.25% carbon and is thus the purest from of iron.
303. What is the specific gravity of cement? [MOD-20]
3.50
2.67
2.15
3.15
ব্যাখ্যা: ব্যাখ্যা: The specific gravity is normally defined as the ratio between the weight of a given volume of material and weight of an equal volume of water. The portland cement have a specific gravity of value around 3.15. Specific gravity of cement is ranging between 3.1-3.16 g/cc.
304. Granite is an example of- [MES-18, MOD-20]
aqueous rocks
sedimentary rock
metamorphic rocks
igneous rocks
ব্যাখ্যা: ব্যাখ্যা: The rocks in which clay content is predominant are called argillaccous rock. (আগ্নেয় শিলা) The rocks are soft in nature and with the presence of water they can be crumbled easily some of the argillaceous rocks are
shale, slate, kaolin, literate etc.
305. In a mortar, the binding material is-[PBRLP-21]
Cement
Sand
Course aggregate
Water
306. What happens when fineness of cement is increased- [PBRLP-21]
It decreases the rate of hydration
It has no-impact on rate of hydration
It increases the rate of hydration
None of the above
307. A good quality of stone absorbs water less than------[BPSC-22]
5%
10%
15%
20%
ব্যাখ্যা: ব্যাখ্যা: A good building stone should be less porous. It should not absorb more than 5% of water. Any stone absorbing 10% of water should be rejected.
308. Seasoning of timber-. [MOD-20]
increase the weight of timber
improves strength properties of timber
does not give dimensional stability
all of these
ব্যাখ্যা: ব্যাখ্যা: The process by which removal of excess moisture content from the timber at a suitable level in conjunction with improving strength is known as seasoning of timber.
309. If two types of sand having FM 2.5 and 2.25 respectively and mix together as same ratio what will be the combined FM? [MOD-20]
2.65
2.37
4.75
4.5
310. Inner part of a timber log surrounding the pith, is called- [PBRLP-21]
Sapwood
Cambium layer
Heartwood
None of the above
311. If water cement ratio decrease, compressive strength of concrete will-. [MOD-20]
increase
decrease
no change
increase
ব্যাখ্যা: ব্যাখ্যা: The water-cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix. A lower ratio leads to higher strength and durability, but may make the mix difficult to work with and form. Workability can be resolved with the use of plasticizers.
312. Which one is the fine aggregate? [MOD-20]
cement
sand
khoa
lime
ব্যাখ্যা: ব্যাখ্যা: Sand, surki, stone screenings, burnt clays, cinders, fly ash etc. are used as fine aggregate in concrete.
313. Gypsum is added in the manufacture of Portland cement in order to- [MOD-20]
shorten the setting time of cement
lengthen the setting time of cement
decrease the burning temperature
decrease the grinding time
ব্যাখ্যা: ব্যাখ্যা: Gypsum plays a very important role in controlling the rate of hardening of the cement. During the cement manufacturing process, upon the cooling of clinker, a small amount of gypsum is introduced during the final grinding process. Gypsum is added to control the "setting of cement".
314. What is the main compound of typical Portland Cement- [PBRLP-21]
CaO
SiO₂
Al₂O3
Fe,O3
315. The clinker is formed at a temperature of-(MOD-20)
500°C
1000°C
1200°C
1500°C
ব্যাখ্যা: ব্যাখ্যা: Portland cement clinker is made by heating a homogeneous mixture of raw materials in a rotary kiln at high temperature. The products of the chemical reaction aggregate together at their sintering temperature, about 1,500°C (2,732°F).
316. Good quality of cement should have higher percentage of-. [MOD-20]
silica
free lime
di-calcium silicate
tri-calcium silicate
ব্যাখ্যা: ব্যাখ্যাঃ tri-calcium silicate-50%
di-calcium silicate-30%
tri-calcium aluminates-10% 1520
Teira calcium-10%
gypsum-5%
317. Efflorescence is caused if-. [MOD-20]
the alkaline salt is present in the bricks
the clay used for making bricks contain pyrite
the water used for pugging the clay contain gypsum
all of the above
ব্যাখ্যা: ব্যাখ্যা: Three factors must be present wherever efflorescence appears:
A soluble salt: A variety of salts and salt-forming chemicals can be present in masonry.
Water: Moisture is the vehicle that carries the salt 10
the surface of the masonry.
Channels: Concrete and bricks have microscopic pores. These tiny channels allow water to move by
wicking action.
318. The chief ingredient of a paint is---- [MOD-20]
thinner
alcohol
drier
pigment
ব্যাখ্যা: ব্যাখ্যা: A pigment is a colored material that is completely or nearly insoluble in water. Generally dyes are often organic compounds whereas pigments are often inorganic compounds. Pigments of prehistoric and historic value include ochre, charcoal, and lapis lazuli.
319. The main purpose of timber seasoning is-[BPSC-22]
to make timber cocter
to made timber fire resistant
to remove moisture at uniform rate
None of the above
ব্যাখ্যা: ব্যাখ্যা: Seasoning of timber is the process by which moisture content in the timber is reduced to required level. By reducing moisture content, the strength, elasticity and durability properties are developed.
320. The diameter of the needle of Vicat apparatus for measuring in initial setting is- [PBRLP-21]
0.5mm
1.0mm
1.10mm
1.50mm