- Author
- Fishburn, C. C. | Watstein, D. J. | Parsons, D. E.
- Title
- Water Permeability of Masonry Walls.
- Coporate
- National Bureau of Standards, Washington, DC
- Report
- BMS 7, October 18, 1938, 37 p.
- Keywords
- masonry | walls | permeability | water | bricks | tests | limestone | clay
- Abstract
- Walls of brick, structural clay tile and hollow concrete unit masonry were tested under conditions resembling exposures to wind and rain and their resistance to the penetration of water determined. Five kinds of workmanship (method of illing joints), three kinds of brick, six kinds of structural clay tile, two kinds of hollow concrete units, and six different mortars were used in the construction of the walls. One group of 48 brick walls included speciments, both 8 and 12 inches thick, of three kinds of brick, four cement-lime mortars, and two classes of workmanship, in all possible combinations. The walls of structural clay tile were faced wither with stucco or with brick of a single variety. Those of concrete units were faced either with the same brick or with cement paint. The effectiveness of several methods of "waterproofing" were compared by retesting some of the walls after they had been treated. The treatments for the walls included the filling of openings in the face joints with mortar, grout, or wax and the application to the exposed surfaces of colorless solutions or paints. Most of the walls were subjected to water penetration tests under two different conditions. Water was applied near the tops of the walls in a manner to produce a thin film of water over their exposed surfaces. In the "capillarity" test no pressure was applied to the exposed face, the water penetrating under the forces of capillarity and gravity only. In the "heavy-rain" test a static air pressure of 10 pounds per square foot was maintained against the exposed face. The performances of the walls in the water penetration tests depended more upon the quality of the workmanship than upon any other factor. Walls of brick having the interior joints well filled with mortar usually gave excellent performances, whereas those with poorly filled joints leaked. Aids in obtaining walls resistant to moisture penetration were the use of mortars of medium or high water retentivity, the wetting of absorptive brick before use, and the application of aparging of mortar on the bakc of the facint wythe. The omission of two-thrids of the normal number of header brick, or the insertion of a limestone sill or belt course had no important effect on the permeability of the walls. On the average , walls with a brick facing and a backing of hollow masonry units were slightly less permeable than brick walls of equal thickness when the joints were not well filled. When the joints were well filled the performance of walls with hollow units was somewhat superior in the capillarity test but inferior in the heavy-rain test to that for otherwise similar all-brick walls. The performances of walls of structural clay tile faced with protland-cement stucco was somewhat better than the average for the walls of brick. The filling of openings in the joints with mortar, grout, or wax was effective in stopping leakage. Applications of colorless waterproofing solutions did not stop leakage through openings in the joints, but were effective in improving the performance of walls of absorptive brick when the openings in the joints had been sealed. Coatings of molten paraffin, oil paint, and cement paint were effective in reducing moisture penetration.