How to Improve Masonry Resistance Against Penetration of Water?
Water penetration can be a significant concern for masonry structures, but there are effective methods to enhance their resistance against water ingress. By considering both the design and construction aspects of masonry, it is possible to create durable and watertight walls.
In this article, we will explore various techniques to improve masonry resistance against the penetration of water, focusing on both design specifications and construction practices.
A. Methods to Improve Masonry Resistance Against Water Penetration:
To enhance the water penetration resistance of masonry, two major categories of methods can be employed: those related to masonry design and those related to masonry construction.
B. Methods Related to Design and Specifications of Masonry:
- Selecting Appropriate Wall Types: It is crucial to choose a wall type suitable for the anticipated severity of forced rain in the project’s location. For areas with heavy rainfall, a completely grouted barrier wall or a drainage wall with a minimum thickness of 20 mm is recommended.
C. Design of Drainage Wall to Improve Water Penetration Resistance of Masonry:
When utilizing a drainage wall, it is essential to prevent water penetration through the outer Wythe of the wall. To maintain the water resistance ability of the outer Wythe, it is crucial to prevent cracks under service load. Factors such as the tensile bond strength of the cement or the flexibility of steel studs should be considered. Additionally, specifying an appropriate sealant for the outer Wythe joint is vital to prevent rainwater penetration.
D. Cavity Walls Design to Improve Masonry Water Penetration Resistance:
If a cavity wall is chosen, proper design is essential to ensure successful drainage. The incorporation of appropriate flashing and weep holes allows water to drain out of the wall cavity in case it enters. Keeping the masonry wall cavity clean by removing mortar debris is crucial. Employing a 50 mm cavity width and using a vapor barrier on the exterior face of the interior Wythe helps prevent interstitial condensation. The use of stainless steel or hot dip galvanized ties is recommended.
E. Design and Detail Considerations to Allow for Differential Movements:
To further enhance water penetration resistance, specific design considerations must be taken into account: a) Clay masonry walls expand due to moisture and freezing, necessitating the installation of horizontal expansion joints. The joint location beneath shelf angles is recommended. Concrete masonry walls, on the other hand, shrink, and the joint under the shelf should not be less than 3.65 mm to accommodate potential closure. Vertical expansion joints at clay masonry wall corners prevent cracks. b) The bond between clay masonry and concrete elements must be broken to prevent cracks caused by differential strain. Control joints should be introduced at concrete masonry openings. c) Restricted differential movement’s influence on wall deformation should be considered when choosing brick and block masonry walls.
F. Construction Methods to Improve Masonry Water Penetration Resistance:
Proper construction practices are essential for achieving effective water resistance in masonry structures.
1. Using Compatible Materials:
It is crucial to use mortar and clay masonry units that are compatible with each other.
2. Following Correct Mortar Mixing and Batching:
Adequate blending of cementitious ingredients with sand and water is essential to ensure proper bonding.
3. Thorough Cleaning and Prompt Installation:
The foundation should be washed and cleaned before masonry installation. Masonry units should be placed immediately after spreading the mortar bed, and excessive tapping should be avoided.
4. Application of Full Head and Bed Joints:
Applying full head and bed joints ensures proper mortar coverage. Raked joints can be employed for interior masonry.
5. Maintaining Mortar Workability:
Retempering can help keep the mortar workable, but mortar should not be used after two hours from initial blending.
6. Damp Curing of Masonry:
Dampening the wall masonry aids in the curing process of the mortar.
Enhancing masonry resistance against water penetration requires a combination of thoughtful design and meticulous construction practices. By considering the recommendations provided in this article, one can significantly improve the durability and watertightness of masonry structures.
Proper selection of wall types, attention to design details, and adherence to construction guidelines will contribute to the long-term performance and functionality of masonry walls against water penetration.