Although it is the fall season in Canada, the drastic decrease in temperature, the whistles of the cold winds and the sporadic snowy days vividly foreshadow the forthcoming winter. While the sight of the nearby terrains and mountains lying peacefully underneath the white blanket of petal-soft snow is heartwarmingly beautiful in the frigid weather, the wrath of winter and its bone-shakingly low temperatures that it brings is undeniable.
Unfortunately, the construction industry and its participants bear the biggest impacts of winter. When you live in a country like Canada, and that too in Calgary, which receives snowfall 88 days each year, the situation is just next level. As long-serving concrete contractors of Calgary and surrounding areas, we must admit, in all honesty, that winter is a challenging season for our realm. Thankfully, we have mastered the art of survival through adherence to industry best practices and innovation.
However, it is sad that some concrete and construction contractors are too adamant to admit the truth about the difficulty. For them, all we can say is you can not change the inherent shortcomings of cement. Nonetheless, you can overcome them through innovation and patience like us.
The truth is that shotcrete services bear the same damage through freezing as other concrete application methods. Thus, a shotcrete service provider must adhere to additional protection protocols and cold weather practices to ensure durability. Otherwise, a contractor’s hard work and the owner’s money will just go down the drain as cracks develop in newly carved surfaces.
Read Also: Pitfalls To Avoid In The Shotcreting Process
For this reason, we recommend that you entrust your small or large-scale shotcrete project to a reliable concrete contractor.
So, in this blog post, we shall give an overview of the practices that will help protect your shotcrete from winter damage.
Shotcrete Services Vs Concrete Pouring In Winter
Owing to the higher cement content, shotcrete generally boasts a higher heat hydration edge over conventional concrete application methods. While this is quite helpful in moderately cold weather, frigid temperatures pose a bigger challenge.
Since shotcrete is applied in thinner layers than traditional concrete methods, it becomes more susceptible to cracking due to cold temperatures. The thin layers offset the hydration heat effect and make surfaces prone to winter damage. For these reasons, shotcrete also requires the same level of winter protection as concrete.
While shotcrete services overcome some of the challenges of traditional concrete methods, it is wrong to assume that shotcrete is magically resistant to everything. Unlike what popular misconceptions portray, shotcrete mandates important processes such as proper curing and winter protection.
Read Also: Consequences Of Cold Weather On Cement Placement
How To Ensure Shotcrete Service Success In The Winter
Before we discuss the methods you as a project owner or contractor ought to use, let us understand what winter protection is and why you need it. Notwithstanding, you must acknowledge that cold weather precautions are necessary both before and after application.
Both shotcrete and concrete applications mandate optimal temperature for the nest results. While freezing the water immediately after application will lead to loss of strength and surface degradation, high temperatures result in evaporation. In turn, this phenomena leads to cracking, shrinkage, etc. Thus, you must take certain precautions if temperatures are below 4.4C or above 25°C.
These special precautions taken in winter are known as cold weather concreting/shotcreting. Now let us divide our best practices into pre and post application precautions:
Pre-Application Cold Weather Shotcrete Protection
- Provide extra heat: Although hydration is an exothermic reaction, its benefits are diminished by the thin layers and extremely low temperatures. Therefore, you should always heat the water you use during the process.
- Use Accelerants: Accelerants like calcium chloride and sodium nitrite speed up the set times if used in the right proportion. These will complement your protection endeavors during the curing process.
- Keep Subgrade temperatures in check: You do not only have to pay attention to air and shotcrete mixture temperatures.The subgrade temperatures are equally important. Do not shoot shotcrete on frozen subgrades.
Post-Application Cold Weather Shotcrete Protection
- Provide immediate insulation: the freeze-thaw durability of shotcrete is a well-known challenge. Since freezing causes water to expand, resulting in increased porosity and diminished compressive strength of hardened surfaces. Thus, you must avoid freezing temperatures until the hydration process is complete and the shotcrete attains a strength of 500 psi. Use insulation blankets and other means to keep temperatures in check for at least 48 hours.
- Extend the protection period and set times: Once the protection is removed, the shotcrete will not gain any strength. Thus, you must extend the protection period to at least three days if not four to ensure the shotcrete reaches optimum strength.
- Do not use water curing: Besides maintaining the temperature at 4.4 °C, we also recommend against water curing during the winter.
About SprayForce Concrete
We are the proud offerers of high-end architectural and structural shotcrete services throughout Calgary and the rest of Alberta. Learn more about SprayForce Concrete.
Have questions? Contact us now.