Blaine permeability

Weiland [42] used a similar idea but based on the Blaine permeability method. An automatic weigher produced a packed bed of powder, of known voidage, in a standard cell. Air was drawn through the bed by the passage of water from one reservoir to another. After a certain volume of air had passed through the bed, measured by a certain volume of water flowing, the time required was converted to an electrical proportionality... 

The specific surface area of eement is eommonly determined directly by air. permeability methods. In the Lea and Nurse method (LI 5). a bed of cement / of porosity 0.475 is eontained in a cell through which a stream of air is f passed, and steady flow established. The specific surface area is caleulated ( from the density of the eement, the porosity and dimensions of the bed of j powder, the pressure differenee aeross the bed, and the rate of flow and ] kinematie viscosity of the air. In the Blaine method (B36), a fixed volume of I air passes through the bed at a steadily deereasing rate, whieh is controlled / and measured by the movement of oil in a manometer, the time required i being measured. The apparatus is ealibrated empirically, most obviously / using a cement that has also been examined by the Lea and Nurse method. The two methods gave elosely similar results. The Blaine method, though not absolute, is simpler to operate and automated variants of it have been devised. 

Figure 25. Schematic representation of an instrument measuring permeability (Blaine)...

Permeability. The rate of flow of a fluid (usually air) through a porous ceramic material per unit area and unit pressure gradient. This property gives some idea of the size of the pores in a body -whereas the measurement of porosity (q.v.) evaluates only the total pore volume. From the permeability of a compacted powder the specific surface (q.v.) of the powder can be deduced. B.S. 1902 Pt. 3.9 describes a gas permeability test applicable to refractory materials, as does ASTM C577. The ASTM C866 test for the filtration rate of whiteware clays depends on their water permeability. See blaine test carman equation lea and nurse... 

Rigden s Apparatus. An air-permeability apparatus for the determination of the specific surface of a powder air is forced through a bed of the powder by the pressure of oil displaced from equilibrium in a U-tube. (P. J. Rigden, J. Soc. Chem. Ind., 62,1, 1943.) The apparatus is essentially the same as that used in the blaine test (q.v.). 

The fineness of grinding of cements may be determined by sieving or a separation method (the fineness being expressed as a certain percentage by weight above a certain size, e. g., as residue retained on a standard sieve), but is more usually based on the specific surface determined by the Blaine method (air permeability of a bed of cement, the result being expressed in cm /g the finer the cement, the higher the specific surface) (see also Section X.1). 

Blaine air permeability testing apparatus (ASTM C 204-51) for determining the specific surface of powders, with permeability cell made of stainless steel, mounted on lacquered rough-service steel plate, with suction fan, filling funnel, 1 set of filter papers, 1 bottle of oil and 1 thermometer graduated in 0.1 C. calibration sand (approx. lOOg), officially certified ... 

Blaine air permeability testing apparatus (ASTM C 204-51) for determining the specific surface of powders, complete, calibration sand (approx. lOOg), officially certified ... 

Blaine filter papers 1.27 cm °/oo 1 electronic air permeability tester type 7207... 

Figure 9.5. Air permeability data, expressed as a Blaine number, can be used to monitor the fineness of a product. The data above compares the fineness of a production run of cement powder, as measured by a Blaine Fineness tester, to data obtained from a diffractometer and converted to Blaine number, a) Data obtained from the Blaine Fineness Tester, b) Diffractometer data converted to Blaine number.

The information summarized in Figure 9.5 can be interpreted in two ways. First, the information generated by the Microtrac could be used to achieve quality control of the cement powder although it appears to be slightly more resolved than the Blaine fineness tester. Vice-versa the other aspect of this data is that if one could automate the use of the Blaine fineness tester the equipment for the Blaine fineness tester is inherently an order of magnitude less, pricewise, than the diffractometers such as the Microtrac (current prices are hard to evaluate but most of the diffractometers available commercially are of the order of 50 thousand dollars and upward, see discussion of diffractometers in chapter 7). In the fall of 1986 a cost benefit analysis carried out at Laurentian University for St. Mary s Cement Co. of Bowmanville, Ontario, concluded that, if development costs were not included, air permeability techniques such as the Blaine fineness tester, generate sufficient control information for many industries at costs which were lower by an order of magnitude than that of a comparable system based upon instruments such as the optical diffractometer [25]. 

As a result of this cost benefit analysis, a project was undertaken at Laurentian University with joint funding from St. Mary s Cement Co., and the research initiative fund of the Ontario Government. The guidelines for this project required the building of a prototype air permeability equipment in which the fineness of cement powder was measured in situ with a feedback time of less than 15 minutes and an accuracy of plus or minus 5 % on the fineness parameter of the Blaine number. The prototype for this equipment is described in the M.Sc. thesis of A. Hoffinan, was delivered to the cement company at the end of the project [26]. 

S. Ober and K. S. Frederick, A study of the Blaine Fineness Tester and a determination of surface area from air permeability data, Symposium on Particle Size Measurement, ASTM Spec. Tech. Publ No. 234. (1958) 279. 

There are several methods to determine the SSA of cement powder. The method most widely used by the cement industry is the Blaine air permeability as it is a simple and quick method. The SSA determined by the Blaine method is referred to as Blaine fineness and it is expressed as total surface... 

In contrast with the air permeability test and LD techniques, nitrogen adsorption does not postulate the particle shape and size or include semi-empirical equations. Nitrogen adsorption also considers the irregularities and porosity of the particles and that is why it is considered a more reliable technique for the scientific community. In addition, the Blaine method or LD techniques are not suitable to determine the SSA of hydrated cement as they are not able to measure correctly fine agglomerated particles as found in most hydrates (Yamada 2011). 

Blaine, R. L. (1943). A Simplified Air-Permeability Fineness Apparatus . ASTM Bulletin, 51-55. 

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