Efflorescence: Evaluation of Published Test Methods for Brick and Efforts to Develop a Masonry Assembly Test Method

Abstract The test method determining the efflorescence potential of brick is found in ASTM C67-08, Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile. This test method is based upon the “wick tests” performed at the National Bureau of Standards in 1930 to determine the tendency for 684 brick to effloresce. Both Britain and Russia have also published efflorescence test methods for brick. From 1995 through 2006, Task Group C15.02.26 on Efflorescence, a subcommittee of ASTM C15.02 on Brick and Structural Clay Tile, evaluated the effectiveness of the ASTM C67-08 efflorescence test method. C15.02 is a subcommittee of committee C15 on Manufactured Masonry Units. The performance results for the ASTM, British, Russian and a modified ASTM C67-08 test on a standard brick were compared. This evaluation revealed that the ASTM C67-08 and the Russian efflorescence test methods were equally effective in predicting efflorescence potential of brick. The British test method was shown not to be effective in predicting efflorescence potential of brick. The efflorescence that developed on the types of brick rated as “effloresced” was more extensive and intense on the brick tested by the ASTM C67-08 method than the brick tested by the Russian method. In 1998, Task Group C15.05.15 on Efflorescence of Masonry Assemblies of ASTM subcommittee C15.05 on Masonry Assemblies prepared ASTM C1400-07, Standard Guide for Reduction of Efflorescence Potential in New Masonry Walls. C15.05 is a subcommittee of committee C15 on Manufactured Masonry Units. Subsequently, Task Group C15.05.15 began testing to obtain information to develop a test method to predict efflorescence potential in new masonry assemblies. The testing is ongoing. The various test methods evaluated to date include the following: (1) Open top plastic box with brick test specimen inserted in each face and filling of the box with a slurry of the test mortar ingredients; (2) open top brick masonry box constructed with the brick and mortar test specimens and filling of the box with water; (3) brick masonry wallettes constructed with the brick and mortar test specimens and placed in 1-in.-deep water and exposed to moving air from a fan; and (4) masonry cubes made from ground-up brick test specimens and mortar test specimens and placed in 1-in.-deep water and exposed to moving air from a fan. This paper presents the results of the evaluation of the ASTM C67-08 efflorescence test method by Task Group C15.02.26 and of the efforts made to date by Task Group C15.05.15 to develop an efflorescence test method for masonry assemblages.