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The fineness of a cement sample is determined by using _________ method.
BlaineтАЩs air permeability
Le Chatelier
universal testing
slump cone
BlaineтАЩs air permeability
The fineness of cement, which represents the particle size distribution, is determined by the Blaine's air permeability method. This test measures the specific surface area, expressed in m2/kg or cm2/g, which correlates to the rate of hydration.
IS 4031 (Part 2): 1999
The fineness of cement, which represents the particle size distribution, is determined by the Blaine's air permeability method. This test measures the specific surface area, expressed in m2/kg or cm2/g, which correlates to the rate of hydration.
S=╧Б1тАЛ╬╖тЛЕLтЛЕVkтЛЕAтЛЕ╬ФpтЛЕtтАЛтАЛ тАФ where S is the specific surface area, ╧Б is the density of cement, and t is the time of air flow.
SsтАЛ=SsтАЛтЛЕTsтАЛTтАЛтАЛ тАФ correction formula for temperature variations in Blaine's apparatus.
The principle is based on the Kozeny-Carman relationship, where air is passed through a prepared bed of cement of definite porosity. The resistance offered to the air flow is directly related to the surface area of the particles. A finer cement provides more resistance, resulting in a slower rate of air flow through the compacted sample.
Fineness affects the rate of hydration and early strength development of cement.
Higher specific surface area indicates finer cement particles.
The test is performed on a standard compacted bed of cement powder.
The test is sensitive to the porosity of the cement bed.
Highly repeatable and accurate.
Non-destructive testing method.
Provides a quantitative measure of particle size distribution.
Requires careful calibration using a standard reference cement.
Sensitive to the degree of compaction in the permeability cell.
Quality control in cement manufacturing plants.
Verification of cement grade and hydration potential in research labs.
Minimum specific surface area for OPC (Ordinary Portland Cement) as per IS standards is 225m2/kg.
Option B (Le Chatelier) is used for soundness testing.
Option C (Universal testing) is used for tensile or compressive strength measurement.
Option D (Slump cone) is used for measuring the workability of fresh concrete.
A is correct тАФ Blaine's air permeability method is the standard procedure to quantify the fineness of cement by measuring its specific surface area.
Always remember that fineness increases the rate of reaction; therefore, finer cement leads to higher early strength but can also increase the heat of hydration and shrinkage cracking risk.
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