If you are laying brick walls or doing anything else of the sort that involves using mortar, then an important thing that you need to know is how long it takes mortar to dry and cure. Moreover, what’s also important for you to know is what the difference between drying and curing is, as well as what the factors are that affect these processes.
In this article, in addition to telling you all that, we’re also going to provide you with some tips on how to speed up the curing process, so let’s get right to it.
Mortar Drying vs. Curing: What’s the Difference?
What you need to know here is that indeed drying and curing are not the same things. When something like mortar dries, this occurs when solvents such as water evaporate from the surface of the film, thus leaving it tacky and dry to the touch. However, just because something is dried does not mean that it is cured.
Technically speaking, the drying of mortar is defined as the process of providing it with the proper conditions to allow the mortar to achieve the right moisture conditions that are appropriate for its intended use.
Curing, on the other hand, is a process where the residual solvents leave the film and then begin crosslinking with oxygen in order to develop increased chemical resistance, hardness, strength, and more. So, when it comes down to it, drying is nothing more than water evaporating from the mixture, whereas curing is an actual chemical reaction that occurs between the various elements in the mortar and the surrounding oxygen.
Technically speaking, the definition of curing is the process that is defined as providing adequate temperature, moisture, and time to allow the mortar to achieve the desired properties for its final use.
How Long Does It Take Mortar to Dry and Cure?
OK, so you do of course need to keep in mind that drying and curing are not the same things. What you need to be aware of here is that mortar actually needs to be kept wet for at least 36 to 48 hours to allow it to fully cure. This, therefore, means that while mortar may dry in as little as 12 hours, if the outside air is very dry and warm, it actually shouldn’t dry for at least 48 hours, or else it will not cure properly.
Therefore, how long mortar takes to dry is actually fairly irrelevant, seeing as you actually need to keep it wet in order for it to cure. Now, in terms of how long it takes for mortar to actually cure, it should reach about 60% of its final compressive strength in about 24 hours.
Although it only takes 24 hours for mortar to cure 60% of the way, it will then take about 28 days or a full four weeks for it to achieve a 100% cure. So when it comes down to it, although mortar will be dry to the touch after about 48 hours, it will not be cured and at full strength for up to a month.
Factors Affecting Curing Time
Of course, not all mortar is going to occur at the same rate, and it all depends on a variety of environmental factors. So what we want to do right now is to take a look at the four main factors that affect the curing time of your mortar.
#1: Air Flow
What is very important is that the mixture stays hydrated while curing. If you have fans pointing at the mortar or there are very high winds, then it will actually strip the mortar mixture of the moisture that it needs in order to stay hydrated and therefore to cure properly.
This does of course seem counterintuitive because you would think that for something to dry and cure that it needs to actually be dry. But with mortar, the exact opposite is the case, as it needs to remain wet and therefore air flow is an enemy.
Yet another factor that will affect how long mortar takes to cure is temperature. Generally speaking, a temperature range between 4.4 degrees Celsius and 37.8 degrees Celsius, or between 40 degrees Fahrenheit and 100 degrees Fahrenheit is ideal for curing mortar. Now, hot weather is not as much of a problem as cold weather.
Extreme cold will affect the hydration of the mortar or in other words, liquids might actually freeze, thus not allowing the mortar to cure properly. If it is too cold outside, your mortar is just not going to cure until it finally gets warmer. If you live in a very cold environment, this can indeed be quite a big challenge.
#3: Mix Ratio
The next factor that will affect how long mortar takes to cure is how much water you put into it while mixing it – the mortar mix ratio you use. The bottom line here is that you absolutely need to follow the directions to a tee in order to achieve the proper mixture.
Adding either too much or too little water to the mortar mixture will not only affect how long it takes to cure, but it will also make the mortar much harder to work with and may even make it unusable.
#4: Ambient Humidity
The fourth and final factor that is going to affect how long mortar takes to cure is how humid the air outside is. Once again, do keep in mind that in order for it to cure properly, it needs to remain fairly wet and humid, which means that if the air outside is extremely dry, then the mortar will not cure properly, and you may actually have to add additional water or moisture to the mix in order for it to cure in a decent amount of time.
Speeding Up the Mortar Curing Process: Tips & Tricks
What we want to do right now is to provide you with a few tips and tricks on how to make mortar cure faster and better:
- If it is not very humid outside, you will need to refer to the instructions on your specific type of mortar in terms of keeping it moist. Spraying it with a water spray might be enough to keep it moist so that it cures faster.
- Never use mortar in extremely cold weather as it just won’t cure. You want warm and sunny weather for working with mortar.
- Seeing as mortar needs to stay wet in order to cure properly, you do need to work in relatively humid weather.
- Many people put special tarps or blankets onto a wet and uncured mortar in order to make it cure faster. Tarps and blankets will help keep wind away and will also keep moisture inside.
- A trick that many bricklayers use is that they actually wet the bricks before putting the mortar on, as this will allow the mortar to stay wet for longer and therefore cure properly.
- Seeing as warmth does play a role here, you can try using a heater in order to heat things up and therefore make the mortar dry and cure a bit faster (while keeping in mind that you need to keep things moist). In other words, you want it to be warm, but still not dry.
As you might realize, most of the tips that we have provided you here aren’t really going to speed up the process because the fact of the matter is that because mortar needs to stay wet for around 48 hours before it will start to fully cure. There is no way to really speed this up.
This process has really nothing to do with speed, but rather with proper execution. As they say, good things come to those who wait, and if you expect your mortar to perform as it should, then you will need to be patient.
There you have it people, everything you need to know about how long it takes mortar to dry and cure, what the difference between drying and curing is, and how to speed up the process for the best results too.