Precast concrete is durable, environmentally friendly, and low-cost, but is it waterproof? Precast concrete isn’t completely waterproof on its own, but it can be – with some help.
Since waterproofing is so important to protect precast concrete, manufacturers are constantly coming up with new ways to create precast concrete that is highly waterproof. Here are some of the main ways they do this.
Reducing Water Help Make Concrete More Watertight
Precast concrete is porous. This means there are pores in concrete that water can seep through. Frozen water expands and this expanding during freezing weather is how cracks start. If this happens, the water can wreak havoc on your concrete. The single best way to protect your fencing is by making sure the concrete is waterproof.
The best way to reduce the number of pores in precast concrete is by reducing the amount of water in the mix. Any water added will create pores in the concrete. Lowering the ratio between the water and the concrete is the most important factor in making precast concrete more watertight.
You need to add more water to allow concrete to flow smoothly into the forms. If the concrete doesn’t flow smoothly and clumps up, it can ruin whole sections of the final product.
So, there is a delicate balance between adding too much water and too little. Any precast concrete producer will be doing precise calculations to ensure precisely the right amount of water.
Additives, or admixtures, are also used to reduce the water needed. Most of the additives used make the concrete more flowable and easy to work – removing the need for extra water.
There are also some additives to reduce the permeability or ability for water to move through the concrete. Some, like hydrostatic permeability reducing admixtures, react with water to create a gel or precipitate that blocks microcracks and capillaries.
There are some other ways of making the concrete more watertight. Some manufacturers also:
- Make sure the curing is happening at an optimal temperature and humidity
- Select aggregate that has low porosity, low absorption, and low permeability
- Add supplementary cementitious materials, which breaks up the pores and makes them shorter
Precast Concrete Should Be Sealed or Coated
While you don’t technically need to seal or coat a properly poured and cured piece of concrete, this is an option to make sure it is waterproof.
Film-forming sealants, which can be water- or solvent-based, create a transparent barrier against the water.
Other sealants like penetrating sealants move into the concrete through the voids and capillaries to form the water repellent layer inside the pores. Concrete is sealed by applying the sealant to the surface of the cured precast concrete.
Coatings form a protective barrier that will protect the concrete from many chemicals – not just water. The most commonly used coatings are epoxy, urethane, or acrylic ones.
All of our precast concrete fencings are sealed as a safeguard against water.
Have a question or want some help with your precast concrete fencing? We’d love to help. Contact us today.