Air-entrained mixes, such as Tarmac Blue Circle Quality Assured Mortar, contain billions of microscopic air pockets that relieve internal pressure on the mortar by providing small chambers for water to expand into when it freezes. Opt for a leading manufacturer to ensure your product is air-entrained. The right productĪnother significant factor to consider in the colder months is the quality of the mortar mix itself. This helps to ensure that you are not putting very cold material into the mix bringing down the overall temperature of the mortar and slowing the overall hydration of the mortar. Before mixing the first batch of mortar, make sure the sand is not frozen, it’s often a good idea to take the top few inches off and place it to one side until it warms up. Protection of the materials prior to use is also important and often over-looked it’s always good practice to sheet your materials overnight, but if it is going to be cold (below freezing), it’s even more important. Protecting new mortar from the elements with a water-resistant tarp or plastic sheeting, proper curing is essential to ensure proper strength gain and help form a strong bond. However, the most serious consequence could be surface scaling, particularly if it was pounding rain. This might include dusting of the surface, resulting in a porous surface that will allow far more water to be absorbed, and a reduced ability of the mortar to resist damage due to freeze/thaw cycles. Without protection from wet weather, you could be left with a weakened surface and the possibility of related problems in the future.
For example, if the fresh mortar was not covered prior to the onset of the rain, and the initial set has not yet occurred (possible due to the cold weather slowing the hydration of the cement) if there was enough rain falling with enough force, the rain may be able wash some of the cement out of the mortar. Consider putting up wind barriers to protect your work and secure the area with plastic sheeting.Īlthough less likely, rain too can cause problems. For this reason, it’s important to make the necessary arrangements to tackle the risk before laying the mortar mix in a windy area. Severe wind can cause premature drying as a result of increased evaporation. In any case, when getting the job done is essential, and there is a risk of frost, protect the mortar with an insulation quilt sandwiched between two sheets of polythene sheeting. If the newly placed mortar does fall below freezing before developing enough strength, it will result in cracking, scaling and crumbling of the product.Īlthough the best advice is to wait for temperatures above 5✬ before doing these jobs, the formation of cracks and spalls are annoyingly unpredictable. Freezing temperatures significantly reduce the compressive strength, the bond strength and also decreases the water penetration resistance of masonry.
It’s also important to keep the mix above 5☌ for 48 hours after it has been placed.
It seems obvious, but this can be easily managed by avoiding mixing or laying the mortar when the air temperature is below 5☌.
Cement will not hydrate sufficiently at low temperatures, which increases the risk of slow setting, poor strength gain and frost (freeze/thaw) damage. The durability and strength of mortar is affected by temperature, and additional care must be taken when working with a mortar mix in colder periods. A critical factor in construction operations carried out in cold weather is ensuring that mortar gets adequate heat for normal cement hydration.
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