Abstract
A variety of tests are currently used to determine surface area in different branches of engineering and industry. This paper analyzes the relationships between these tests based on the results obtained by each test for a group of nine red tropical soils collected in the north east of Brazil. The ethylene glycol monoethyl ether (EGME) method that showed a good correlation with direct measurement of particle size by electron microscopy, is taken as a base for the graphical representation of results. Conversion factors between the tests and the EGME test and the standard deviation of the conversion factors are calculated.
The results show that test procedures can be divided into three groups in terms of increasing spread in the test results - polar molecules and direct measurement tests with a spread of less than 15%, methylene blue and BET tests with a spread of about 30% and Blaine, Fisher and granulometric tests with a spread of about 50% when plotted against EGME data. It is noted that the test methods that gave a larger spread are used in industry and process control, because they may be performed quickly at a modest cost. The more accurate methods are slower and in some cases more expensive.
