Blain Air Permeability Apparatus

Product Description

Blain Air Permeability Apparatus: MTCT-03

The Blaine air permeability apparatus is used to determine the fineness of Portland cement in terms of the specific surface expressed as total surface area in square centimeters per gram of cement. The Blaine apparatus draws a defined volume of air through a prepared bed of cement of defined porosity.

The Blaine air-permeability apparatus consists essentially of a means of drawing a definite quantity of air through a prepared bed of cement of definite porosity. The number and size of the pores in a prepared bed of definite porosity is a function of the size of the particles and determines the rate of airflow through the bed. The apparatus illustrated.

Technical Specification

• Fineness of cement has a great effect on the rate of hydration and hence the rate of gain of strength.
• Fineness of cement increases the rate of evolution of heat.
• Finer cement offers a great surface area for hydration and hence faster the development of strength.
• Increase in fineness of cement also increases the drying shrinkage of concrete and hence creates cracks in structures.
• Excessive fineness requirement increases cost of grinding.
• Excessive fine cement requires more water for hydration, resulting reduced strength and durability.
• Fineness of cement affects properties like gypsum requirement, workability of fresh concrete & long term behavior of structure.
• Coarse cement particles settle down in concrete which causes bleeding.
• Approximately 95% of cement particles are smaller than 45 micrometers, with the average particle around 15 micrometers.
• In the early 1900s, cement fineness was expressed as the mass of cement per fractional size (percent weight retained on specific sieve sizes). Now a day„s fineness is usually measured by the Blaine air-permeability test that indirectly measures the surface area of the cement particles per unit mass.
• Cements with finer particles have more surface area in m2 per kg of cement.