Mortar can be useful in pond building. if mixed and applied correctly, it has superior adhesion when compared to waterfall foam
It also allows for leveling and raising stone etc. which is less costly and/or more difficult to achieve by other means |
As it pertains to ponds, mortar is utilized to adhere stone together, leveling, and to contain water. It is important to realize however, neither mortar or concrete are waterproof on their own
To create a waterproof structure there are several options. For one, a liner should be placed underneath the stone. I have seen a number of leaking concrete ponds without a liner underlay. Waterproofing powders/mixes can also be added to the mortar mix to create a water tight seal. Liquid rubber or fiberglas can also be painted on a cured concrete thereby rendering it watertight. Personally I prefer the use of a EPDM rubber liner
The big key with mortar or concretes that it should be allowed to dry slowly so that the chemical reaction is properly completed. If the mortar does not cure properly it will not have any strength. To slow the drying process, the mortar should be sprayed down with water several times a day in order to keep it moist. In excessively hot weather it should be covered with burlap to stop it from drying out rapidly. Also make sure not to add too much water creating a sloppy mix, this also lessens the final strength |
You can buy ready to mix mortar in a bag or mix the constituents on your own. I prefer to mix my own. When you mix your own, you can control the ratio of them. Pictured above left are the 3 main components. From L to R, Portland cement, Masonry cement and Sand. I prefer a mixing ratio of 1:0.5:3. Type S cements are stronger than type N and should be chosen. Soft sand is also desired over gritty sand when doing stone work
Masonry cement provides a strong bond as well as being able to deal with freezing and thawing. Portland cement supplies flexural strength and adhesion |
When applying mortar to rocks, it is a good idea to prep them with a wire brush. This is easily accomplished with a cordless drill. This cleans any dirt and loose debris away
You should also wet the stone or even apply a slurry mixture made of portland cement and bonding agent
When stacking the stones, pack the mortar in as best as possible and be aware of aesthetics. It is usually not advisable to stack more than 3 stones (2 layers of mortar between the 3 layers) before letting the mortar cure - stability or placement will likely be an issue if you do
Of course waterfall foam is a good alternative to mortar and it is particularly advantageous when trying to get a quick seal and bond between liner and stone |
