In ordinary building work little care is usually given to inspec tion of the materials, and defective work frequently results from the use of poor bricks. Seriously defective bricks are so easily detected by inspection that there is usually no excuse for their inclusion in brickwork of good character.
A Committee of the American Society for Testing Materials has been for some time studying the matter of a standard specifica tion and standard tests for building brick. They have suggested tentative methods for classification of brick and for making tests for absorption, compressive strength, and transverse strength.
The committee recommends that the standard sizes for building brick shall be 21 by by S inches.
They also recommend the following classification of bricks: (a) According to the results of the physical tests, the bricks shall be classified as vitrified, hard, medium, and soft bricks on the basis of the following require ments: (b) The standing of any set of bricks shall be determined by that one of the three requirements in which it is lowest.
The methods proposed for making these tests are given in the Proceedings of the Society for 1919, Part 1, p. 513.
Durability durability of bricks under difficult weather conditions is one of their most valuable qualities. Tests are some
times made of the effect upon bricks of freezing while in a saturated condition. These tests have been made in various ways, usually by immersing the brick in water, then freezing and thawing it repeat edly, commonly twenty repetitions, and determining the loss of weight or of strength. Very soft, porous bricks may be disinte grated by such treatment; those of low absorption and good strength usually show but slight effect.
The Committee of the American Society for Testing Aiaterials, in 1913, suggested a method for making this test. They have not, however, found it of sufficient value to include in their later speci fications.
A test in which the brick is saturated with a solution of sodium sulphate, which is then allowed to crystallize in the pores of the brick, has sometimes been used, the results of this action being similar to those of freezing, but much more rapid and severe. A study of this method has been made for the Committee by Pro fessor Edward Orton, Jr.' and it seems probable that it may become a standard method of testing brick. It has not yet been definitely formulated for use in specifications.