Introduction
Brickwork spalling, characterised by the flaking, cracking, peeling, crumbling, or chipping of stone or bricks, poses both aesthetic and structural concerns in the field of construction. This phenomenon occurs due to various factors such as water penetration, freezing, heating, and mechanical processes. In this article, we will delve into the causes of brickwork spalling, its implications, and effective measures to prevent and remedy this issue.
Causes of Brickwork Spalling
Moisture Penetration: Older bricks are particularly susceptible to spalling as they deteriorate over time due to moisture infiltration. This gradual penetration leads to the crumbling of bricks, ultimately resulting in spalling.
Cement Pointing over Lime Mortar Joints: In solid walled buildings, the use of cement pointing over soft lime mortar joints can contribute to spalling. Moisture primarily escapes through mortar joints, acting as the lungs of the wall. When these joints are blocked with cement, moisture attempts to escape through the brick faces, causing them to blow or spall.
Freezing and Expansion: Water absorption by the porous surface of old bricks, combined with freezing temperatures, can trigger spalling. The expansion of water during freezing exerts pressure on the bricks, leading to cracking and subsequent spalling.
Weather and Environmental Factors: Changes in weather, humidity, and temperature also contribute to brickwork spalling. Minor structural movements can create cracks in the mortar, allowing moisture to penetrate and accelerate spalling. Nitrate emissions from diesel vehicles, which produce nitric acid, can severely damage stonework with a carbonate binder.
Implications of Brickwork Spalling:
Brickwork spalling can have varying implications, ranging from purely aesthetic concerns to serious structural damage. Understanding these implications is crucial for determining the appropriate remedial actions.
Aesthetic Concerns: Spalling affects the visual appeal of the building, leading to an unsightly appearance and reducing its overall value.
Structural Integrity: If left unaddressed, spalling can compromise the structural integrity of the building. Dislodged or weakened bricks pose safety risks, requiring costly repairs and restoration.
Prevention and Remedial Measures:
To prevent and address brickwork spalling effectively, the following measures should be implemented
- Avoid Masonry Sealants: Masonry sealants should not be used as they trap moisture and salts, exacerbating spalling. Instead, opt for more suitable solutions.
- Replace Masonry Paints: Plastic-based masonry paints such as Sandtex and Weathershield should be removed and replaced with limewash if a coloured finish is desired. Masonry paints can trap moisture, leading to spalling and damp walls.
- Improve Drainage: Proper drainage around the building can prevent water pooling near the foundation, thereby reducing the risk of damp walls and spalling. Address any leaks and defects that contribute to penetrating dampness.
- Identify and Address Moisture Sources: When spalling has already occurred, damaged bricks can be replaced. However, it is crucial to identify and rectify the underlying moisture source to prevent further spalling.
- Use Appropriate Tools: When replacing damaged bricks, avoid using angle grinders as they can damage the edges and expose the bricks to spalling. Instead, opt for tools like the plunge masonry saw, which provides a more suitable cutting method.
- Address Crypto florescence: In cases of crypto florescence, where salts crystallise below the surface of bricks or stone, spalling can occur. This issue is associated with a build-up of salts and is often observed when weak bricks are inappropriately reused or when surface treatments force
