Hydraulic cement is a god-sent for fixing leaks through masonry. Once cured, it becomes waterproof and stops water from leaking or infiltrating through walls, ceilings, or foundations. Problems arise when the hydraulic cement is not drying. Why does it happen, and what can you do about it?
If hydraulic cement still looks wet a long time after you’ve applied it, the cement is most likely old, or you used too much water when mixing it. Improper preparation, improper application, application onto a dirty surface or cold temperatures can also prevent it from bonding with the substrate and prolong curing time.
Hydraulic Cement Still Looks Wet: 6 Reasons & Fixes
One of the main mistakes people make when working with hydraulic cement is spreading it over a wide surface. Hydraulic cement isn’t mortar, and you’re not supposed to use it in the place of mortar. Instead, you should use it to fill cracks and gaps in masonry that could let water leak or infiltrate. If you have used it for the intended purpose, but the hydraulic cement is not drying, you are likely dealing with one of the situations below.
1. Too Much Water In Hydraulic Cement
Anyone planning to work with hydraulic cement has at least read that moisture acts as a hardener. In an attempt to make hydraulic cement easier to apply, you might mix it with more water than indicated on the label, thinking that nothing can go wrong.
But do you want to know what happens if you apply too much water to hydraulic cement? The mixture becomes too soupy and has the potential to bleed into masonry, segregate, and remain wet instead of curing.
To fix the issue, you’ll have to remove the bad hydraulic cement from the openings you just patched, make a new cement batch, and fill the cracks or holes again.
When mixing the new hydraulic cement batch, remember to mix the cement in small quantities at a time. Use as much water as indicated on the label – the final compound should have a stiffer, dryer texture, similar to peanut butter.
For the best results, you should mix the powder and water with a mechanical mixture. Add the water first and then the powder.
2. Old Hydraulic Cement
When using cement, the last thing to cross your mind is an expiration date. Does hydraulic cement go bad?
Unfortunately, it does. Hydraulic cement has a shelf life, and it might not cure if you use expired powder.
The shelf life may vary from brand to brand but is generally short. Generally, hydraulic cement has a shelf life of about one year after the production date in a new, unopened container. Once opened, you should use it as quickly as possible. Otherwise, the moisture in the air can cause it to harden and go bad.
To prevent unpleasant surprises after application, always check the production date and shelf life of the product you want to use. If you have an opened container that has been sitting around for a few months, it is a better idea to buy a new one.
3. Improper Cement Preparation
Sometimes, you might use the water quantity indicated on the package only to see that the hydraulic cement doesn’t dry anyway. One of the culprits could be the preparation technique.
For proper preparation, you must first pre-wet the mixing container and throw away the excess water. As explained above, you should then add the right quantity of water and then the powder. Mix thoroughly to obtain a smooth, homogeneous compound.
Since hydraulic cement sets very fast, only prepare small batches at a time. Don’t add more water, thinking you’ll gain more time before it sets. The only thing you’ll get is improperly mixed cement that might set either faster than expected or not at all.
The video below explains how to mix and apply hydraulic cement:
4. Improper Application
Understanding the materials you’re working with is crucial for a successful outcome of your project. As far as hydraulic cement is concerned, this material is a filler but not a core filler. You can’t spread it as regular cement to cover brick or other masonry materials. You can’t use it as mortar, either.
Hydraulic cement needs to be confined to create the physical and chemical interlock. Otherwise, it won’t cure, and it will look wet days or weeks after application.
An easy fix is to use hydraulic cement for its intended purpose, which is to fill cracks, holes, and other openings if you want to create a waterproof surface.
5. Dirty Surface
As a builder – even a DIY one – you should know that every masonry material should be applied on a clean surface. Dust and debris can prevent hydraulic cement from binding to the substrate, impairing its curing properties and prolonging the drying time.
Before applying the cement, make sure the surface is free of dust, oil, grease, and other kinds of debris.
The good news is that the surface doesn’t have to be dry when applying hydraulic cement. The material adheres better to a damp surface, so simply clean the application spot with a degreaser, rinse with abundant clean water, and apply the mixed hydraulic cement right away.
6. Cold Temperature
Lastly, the environmental temperature can influence the drying time. Hot temperatures can cause the mixture to dry and set faster, whereas cold temperatures can keep the mixture wet for a longer time.
You can prevent this by applying hydraulic cement only when the temperatures are between 45°F and 90°F. Avoid rainy days, as excessive air humidity can speed up the hardening process.
What Is The Cure Time For Hydraulic Cement?
In optimal conditions, hydraulic cement sets in about five minutes. However, it needs about 28 days to fully cure.
The cement achieves a compressive strength of about 2,000 PSI one day after it has been set. The compressive strength goes up to 5,500 PSI in about a month.
Can you use hydraulic cement on wet surfaces?
Yes. In fact, hydraulic cement adheres better to a wet surface. Remember, though, that you should not add more water to the cement in an attempt to speed up (or slow down) its setting time. Always mix the powder as instructed on the tub.
Does hydraulic cement dry hard?
No. Hydraulic cement dries very easily when mixed and applied correctly. If it takes more than five to ten minutes for the cement to dry after you’ve applied it, you should remove it from the opening you’ve filled, mix another batch, and fill the crack or hole again.
Does hydraulic cement go bad?
Yes. Hydraulic cement goes bad about a year after its manufacture date if kept in its original, unopened container. It can go bad faster if the container is open.
Hydraulic cement is a life-changer when it comes to waterproofing masonry surfaces, including basements, swimming pools, and other structures that can be affected or submerged in water. However, working with it can be a nightmare if you don’t know what to expect. We hope this guide can help you use hydraulic cement correctly and understand what has gone wrong if the mixture you applied remains wet and doesn’t set or cure.