Cold Weather Masonry Construction
Cold weather poses unique challenges for masonry construction. The low temperatures affect the properties and behavior of mortar, leading to potential issues such as cracking and reduced strength.
However, by implementing specific techniques and precautions, builders and contractors can overcome these challenges and ensure successful masonry construction even in cold weather conditions.
In this article, we will explore the effects of cold weather on mortar and provide valuable tips for working with masonry and mortar during cold weather.
Effect of Cold Weather on Masonry Mortar:
When the surrounding temperature drops, the mortar used in masonry construction experiences several effects that can impact its performance. These effects include:
- Volume Change: As the temperature of the mortar falls below normal, the water present in it freezes and causes a volume change, leading to mortar expansion. Consequently, the quantity of water required to reach the desired consistency decreases.
- Reduced Hydration Process: Lower temperatures slow down the hydration process and subsequent strength gain of the mortar mix. This can result in prolonged curing times and delayed project schedules.
- Delayed Setting Time: The initial and final setting times of the mortar are significantly delayed in cold weather conditions. It requires careful monitoring to ensure the mortar sets properly within the desired time frame.
- Cracking and Bonding Issues: Freezing water within the mortar can cause cracks to form, compromising the integrity of the structure. Additionally, the presence of ice on the surface of masonry units hinders the bond between the mortar and bricks, affecting the overall strength of the masonry.
- Reduced Strength Gain: Cold temperatures slow down the rate of strength gain in the mortar, requiring extended curing periods to achieve the desired strength.
Tips to Work with Masonry and Mortar in Cold Weather:
To overcome the challenges posed by cold weather during masonry construction, consider the following tips:
- Optimize Material Selection: Choose masonry materials that are specifically designed for cold weather performance. This ensures better compatibility and resistance to temperature-related issues.
- Protect Raw Materials: Store all masonry materials in a sheltered area to prevent them from exposure to ice and cold weather. Cover them with tarps or use planks to keep them elevated above the ground.
- Heat Materials and Mortar: Warm the masonry units and materials before their application. This can be achieved by storing them in a heated space or using heating blankets. Similarly, heat the mortar during mixing and application to maintain workability.
- Insulate Structures during Curing: After the masonry construction is complete, insulate the structures to maintain a suitable temperature for proper curing. This can be done using insulation blankets or covers, which help trap heat and prevent moisture from freezing.
- Protect Work Areas: Enclose or protect the work areas to shield them from cold winds and other adverse weather conditions. Temporary structures or heated enclosures can provide a controlled environment for masonry construction.
- Ensure Worker Safety: Prioritize the safety of workers by providing them with appropriate protective clothing and equipment. Cold weather gear, such as insulated gloves and warm clothing, should be provided to prevent cold-related injuries.
Storing and Handling Materials for Masonry Construction in Cold Weather:
Proper storage and handling of materials are crucial for successful masonry construction in cold weather. Consider the following guidelines:
- Prevent Exposure to Rain and Snow: Protect all masonry materials from rain and snow by placing them on elevated planks and covering them with tarps or waterproof covers.
- Ensure Dry Mortar Ingredients: Use dry bulk mortar ingredients to avoid any issues caused by frozen or wet materials.
- Handle Frozen Aggregates: If fine aggregates are delivered with frozen lumps, heat and break them into sand before use.
- Place Units on Unfrozen Surfaces: Ensure that masonry units are placed on unfrozen surfaces with temperatures not less than 20°F. The surfaces should be free from ice and snow.
- Pre-warm Masonry Materials: Heat the masonry units and materials before construction to facilitate proper cement hydration.
- Avoid Freezing of Mortar: Place the mortar on heated surfaces, such as metal, to prevent freezing. This ensures optimal workability and bonding.
- Caution with Glass Masonry Units: Glass masonry units should not be installed during cold periods due to their increased susceptibility to damage.
Mixing Mortar for Cold Weather Masonry:
Proper mortar mixing is crucial for cold weather masonry construction. Follow these guidelines:
- Mix Smaller Amounts: Mixing smaller amounts of mortar at a time helps prevent the materials from absorbing water and reduces the risk of freezing.
- Heat and Maintain Temperature: Heat the mortar and maintain its temperature during the mixing process. Avoid excessive drying due to external warming, as it can affect the mortar’s properties.
- Heat Sand and Water: If necessary, heat the sand and water before mixing to maintain the mortar temperature below 40°F. When using hot water, mix it with cold sand first to prevent the cement from flash setting.
- Use Accelerators or Admixtures: To increase the rate of hydration and early-age strength development, consider using accelerators or admixtures specifically designed for cold weather masonry mortar. However, ensure that the use of admixtures aligns with project specifications and guidelines.
- Place Masonry on a Sound Foundation: Always place masonry on a sound and unfrozen foundation. Avoid placing it on surfaces covered with snow or ice, as this can reduce the bond between the masonry units and the foundation.
Once the masonry construction is complete, it is essential to protect the new structures from cold weather conditions. Follow these steps:
- Cover Walls with Plastic: During temperatures below 32°F, cover the walls with plastic to prevent water from entering the masonry.
- Insulation Blankets: For temperatures between 32°F and 20°F, use insulation blankets to prevent heat loss from the walls.
- Maintain a Suitable Temperature: If the temperature drops between 20°F and 0°F, maintain the walls at around 40°F using 1-inch insulation blankets. Both sides of the masonry wall can be heated to achieve this.
- Install Windbreakers: In areas with wind speeds exceeding 15 miles per hour, install windbreakers to minimize the impact of strong winds on the newly constructed masonry.
Cold weather masonry construction requires careful planning and implementation of specific techniques to overcome the challenges posed by low temperatures. By optimizing material selection, protecting raw materials, heating materials and mortar, insulating structures, and prioritizing worker safety, builders and contractors can successfully carry out masonry construction projects even in cold weather conditions. Additionally, proper storage and handling of materials, careful mortar mixing, and post-construction protection of masonry structures are crucial steps in ensuring the longevity and quality of the completed projects. By following these techniques, cold weather masonry construction can be executed effectively, minimizing the impact of adverse weather conditions on the construction process and the resulting structures.