How Should Cold Weather Masonry Construction Be Planned?

 How Should Cold Weather Masonry Construction Be Planned?

Cold weather masonry construction necessitates a number of precautions on the part of the builders. To avoid seasonal construction delays caused by cold weather, the builder or contractor employs dynamic procedures, equipment, mason contractors, supplies, and so on.

The "Specification for Masonry Structures" of ACI 530.1-08/ASCE 6-08/TMS 602-08 specifies the minimum requirements for cold weather masonry construction. Masonry construction must be carefully planned in areas where the temperature is less than 44oF (4.4oC). Cold weather alters the properties and behavior of masonry mortar, eventually leading to cracking and other problems. As a result, masonry construction in cold weather necessitates special precautions to keep the mortar warm and workable.

This article discusses the effects of cold weather on mortar as well as masonry construction tips for cold weather.

Cold Weather's Impact on Masonry Mortar

The low temperature of the surrounding environment lowers the temperature of the mortar below normal, resulting in the following effects:

1. When the temperature of the mortar falls below normal, the water freezes and causes a volume change, causing the mortar to expand. As a result, the amount of water required to achieve a given consistency decreases.
2. Lower temperatures slow the hydration process and reduce the strength gain of the mortar mix.
3. The mortar's initial and final setting times are significantly delayed.
4. The freezing of water present in the mortar is just enough to cause cracks. Ice on the surface of masonry units weakens the bond between the mortar and brick units.
5. The rate of strength gain of mortar is slowed during cold temperatures.

Working with Masonry and Mortar in Cold Weather

The following are general guidelines to follow when performing masonry construction in cold weather:

1.The cold weather performance of masonry materials must be optimized.

2. Keeping raw materials safe from ice and cold weather.

3. Applying the material and mortar while it is hot.

4. Insulating the structures while they cure (Figure-2).

5. Defending or enclosing work areas (Figure-3).

6. Keep the site's workers safe (Figure-4).

Figure 2: A makeshift shelter to keep rain and snow off the mortar preparation area.

Figure 3: A cold masonry construction that has been protected.

Figure 4: Work area enclosure and heating to protect materials, workers, and installed masonry from extreme cold weather.

Workers appear to be less productive in cold weather. According to a field observation conducted by the Portland Cement Association, workers working within a protected area were found to work until 12°F to 2°F (PCA). A better working environment for mixer operators can significantly increase their productivity.

Figure 5: ASTM cold weather construction requirements.

Cold-weather storage and handling of masonry construction materials

1. All masonry construction materials must be protected from rain and snow. The materials can be placed on planks and covered with tarps for this purpose.
2. Always choose dry mortar ingredients that are delivered in bulk.
3. The delivered fine aggregates may contain frozen lumps. These can be heated and crushed to make sand.
4. The masonry units must be installed over unfrozen ground. The surface temperature must not be less than 20°F. It must be clear of ice and snow.
5. Prior to construction, always heat the masonry materials. This promotes cement hydration.
6. To avoid freezing, the mortar should be placed on heated surfaces such as metals.
7. During cold weather, glass masonry units should not be installed.

Cold Weather Masonry Mortar Mixing

1. Mix the mortar in small batches. It would prevent the materials from absorbing water. As a result, frosting is restricted.
2. Heating and maintaining temperature are used to place the mortar. Do not allow the mortar to dry out too quickly as a result of external warming.
3. The mortar sand or water can be heated and mixed. It would assist in keeping the mortar temperature below 40°F.
4. If hot water is used, it must first be mixed with cold sand before being mixed with cement. This is done to prevent the cement from flash setting.
5. By using high-early cement, the rate of hydration can be increased. To accomplish this, an accelerator or admixture can be used. Accelerators are used to speed up the development of early-age strength. As a result, they do not allow the mortar to dry.

Cold Weather Protection for New Masonry Structures

1. Cover the walls with plastic once the masonry construction is completed. When temperatures are below 32°F, plastic prevents water from entering the masonry.
2. Heat loss can occur at temperatures ranging from 32°F to 20°F. This can be avoided by wrapping the wall in insulation blankets.
3. When the outside temperature is between 20°F and 0°F, the walls must be kept at around 40°F. It can be done with a 1-inch insulation blanket. Heating can be applied to both sides of the masonry wall.
4. If the wind speed in the area exceeds 15 miles per hour, windbreakers can be installed.

The primary goal of a cold weather construction plan is to reduce and eliminate the negative effects of cold weather on masonry materials, construction, and workforce in an economical manner. The mason contractor must assess the efficacy and practicability of the techniques used in relation to the specific project and weather conditions.

Questions and Answers

What are the specifications for cold-weather masonry construction?

The "Specification for Masonry Structures" of ACI 530.1-08/ASCE 6-08/TMS 602-08 specifies the minimum requirements for cold weather masonry construction. Masonry construction must be carefully planned in areas where the temperature is less than 44 degrees Fahrenheit (4.4 degrees Celsius). Cold weather causes changes in the properties and behavior of masonry mortar. The following are the general requirements for cold weather masonry construction:

1. The cold weather performance of masonry materials must be optimized.

2. Keeping raw materials safe from ice and cold weather.

3. Applying the material and mortar while it is hot.

4. Insulating the structures while they cure.

5. Defending or enclosing work areas.

6. Keep the site's workers safe.

Can masonry units be used in masonry construction in cold weather?

During cold weather masonry construction, dried masonry units must be used. Wet and frozen masonry units weaken the bond between the masonry units and the mortar. This would eventually have an impact on the quality and strength of the wall assembly.

What exactly is a cold weather construction strategy?

The primary goal of a cold weather construction plan is to reduce and eliminate the negative effects of cold weather on masonry materials, construction, and workforce in an economical manner. The mason contractor must assess the efficacy and practicability of the techniques used in relation to the specific project and weather conditions.