This set of Concrete Technology Multiple Choice Questions & Answers (MCQs) focuses on “Silica Fume”.
1. What is Silica Fume?
a) Silica fume is a byproduct of producing silicon metal or ferrosilicon alloys
b) Silica fume is a mono product of producing silicon metal or ferrosilicon alloys
c) Most commonly found in nature as quartz and in various living organisms
d) Hydrocarbon combustion affords the two principal carbon oxides: carbon monoxide and carbon dioxide
View Answer
Explanation: Silica fume is a byproduct of producing silicon metal or ferrosilicon alloys.
2. Silica fume is ______________
a) Less reactive
b) Neutral
c) More reactive
d) Absent in concrete
View Answer
Explanation: One of the most beneficial uses for silica fume is in concrete, because of its both properties, it is a very reactive pozzolana.
3. Concrete containing silica fume can have very __________ strength and can be very __________
a) Low, Durable
b) High, Durable
c) Low, brittle
d) High, brittle
View Answer
Explanation: Concrete containing silica fume can have very high strength and can be very durable.
4. Content of SiO2 in silica fume is ___________
a) 52%
b) 35%
c) 21.9%
d) 85-97%
View Answer
Explanation: The content of SiO2 in silica fume is 85-97%. 35% is the content of SiO2 in Calcareous (ASTM C618 Class C) Fly Ash.
5. Content of CaO in silica fume?
a) 5
b) 21
c) 40
d) <1
View Answer
Explanation: The content of CaO in silica fume is less than 1. 21 is the content of CaO in Calcareous (ASTM C618 Class C) Fly Ash.
6. The specific surface (m2/kg) of silica fume.
a) 370
b) 15000-30000
c) 45000
d) 420
View Answer
Explanation: The specific surface area of silica fume can be measured with the BET method or nitrogen adsorption method. It typically ranges from 15,000 to 30,000 m2/kg.
7. Specific Gravity of silica fume.
a) 2.38
b) 2.65
c) 2.94
d) 2.22
View Answer
Explanation: The specific gravity of silica fume is generally in the range of 2.2 to 2.3.
8. Bulk density of the silica fume varies from ____________
a) 130-600 kg/m3
b) 650 kg/mm3
c) 75-150 kg/mm3
d) 750 kg/mm3
View Answer
Explanation: The bulk density of silica fume depends on the degree of densification in the silo and varies from 130 (undensified) to 600 kg/m3.
9. Spherical particles in silica fume has diameter of _______
a) <1 μm
b) >1 μm
c) 1 μm
d) .1 μm
View Answer
Explanation: Silica fume is an ultrafine material with spherical particles less than 1 μm in diameter, the average being about 0.15 μm.
10. Silica fume is usually added during ____________
a) Before concrete production at a concrete plant
b) After concrete production at a concrete plant
c) Concrete production at a concrete plant
d) Curing
View Answer
Explanation: Silica fume for use in concrete is available in wet or dry forms. It is usually added during concrete production at a concrete plant.
Sanfoundry Global Education & Learning Series – Concrete Technology.
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