A clear indicator that your concrete has moisture damage, is the forming of damp patches or wet spots on the surface of your concrete. Wet spots not only damage the structural integrity of your concrete but can prevent protective coatings from sticking. This is why it is so important to test your concrete for moisture.
Rain on freshly finished concrete can damage the surface, and in extreme cases, wash the surface off the concrete exposing the aggregate. To prevent this, covering the concrete with hessian will protect the surface from running water, reducing the risk of erosion.
Water damage in a foundation is often gradual, starting with small cracks allowing in small amounts of water. This weakens the foundation and lets in more water. This process can take months or even years to destroy your foundation.
Repair Guidelines
Clean the damaged surface before beginning repair for light scaling. Use a pressure washer to spray away crumbling cement, dirt, plants and stains. Resurface the affected area with a finishing seal. Once dry, apply a waterproof coating to help prevent further degradation.
When water is added to the cement it chemically reacts to form a paste that binds the components together. The water evaporates as the concrete dries, which increases the product's tensile strength. This process is known as curing.
Even after the concrete is cured, excess water still must evaporate from the concrete. While it only takes around 28 days to cure concrete, drying can take months.
Use your home or office dehumidifier to dry out the affected space, especially if the humidity level is above 50%. Create air movement. To speed up the drying process, place fans in the affected room close the doors. The air movement will help dry out the concrete.
Work the mix with a hoe, gradually adding water, until the mix reaches a uniform, workable consistency. Properly mixed concrete should look like thick oatmeal and should hold its shape when it is squeezed in a gloved hand.
The culprits of blotchy concrete after sealing
When you find yourself staring at discolored concrete that has already been sealed, there are usually three potential sources of blame: The sealer was applied poorly. Not enough sealer was applied. The concrete itself had varying absorption rates.
When a blemish appears on the surface of a concrete slab it will likely be one of these: blisters, cracking, crazing, curling, delamination, discol- oration, dusting, efflorescence, low spots, popouts, scaling, or spalling.
Plastic shrinkage concrete cracks
When that water eventually leaves the slab, it leaves behind large voids between the solid particles. These empty spaces make the concrete weaker and more prone to cracking. This type of cracking happens frequently and is referred to as “plastic shrinkage cracking”.
Generally, it takes around 72 hours for any affected area to dry up completely, but this only applies on a room-to-room basis. Larger areas impacted by water damage take longer to dry. Regardless of what caused the water damage, you need to follow specific protocols to reinstate your house to its pre-damage state.
Concrete should be sealed to protect from mold and mildew.
You'll know you have mold growing on your concrete by the greenish color that appears. When you seal your concrete, you inhibit moisture from penetrating the surface and therefore prevent the development of mold and mildew.
Salt does not damage concrete, but the effects of salt can. That sounds weird, so we'll explain. Salt does not chemically react with hardened concrete. Salt does however lower the freezing point of water, attract moisture, and increase pressure of frozen water.
Concrete spalling describes the state when the concrete begins to degrade or break away. Common signs include cracking, crumbling or flaking concrete, rust stains or bubbling on the concrete or cement render – plus leaks in the roof and walls.
What does mold on concrete look like? Mold might look like black spots or areas that have turned green. Some mold is white, but can be confused with efflorescence, which is a salty film on the concrete. If the white substance dissolves easily with water it is likely the latter.
Spalling looks like pitted acne scarring and breaks off in flecks which can expose rebar. These divots vary in diameter and depth but can be thicker than 5 inches and just under an inch in depth.
This type of discoloration is usually removed by high-pressure washing with high-pressure water and, if necessary, chemical cleaning agents. The use of calcium chloride on concrete can discolor the surface.
Cleansing — For mild discoloration, repeatedly flushing the hardened concrete surface with hot water, then scrubbing with a stiff brush, can reduce or remove discolored blotches. Acid treatment — If the discoloration is more severe, a mild acid solution of 1-3% muriatic acid to water can help remove the discoloration.
Usually this white or off-white discoloration to concrete and masonry forms when soluble salts and other water dispersible materials come to the surface through capillary voids as a result of temperature changes, moist migration, condensation, rain, dew, and/or too much water in the mix.
Here are some slab leak symptoms to look out for: A raised “dome,” water stains, or warm spots on the floor. Foundation heaving caused by shifting or swelling soil. An increase in water or heating bills, as well as low water pressure.
Slab leaks can cause heavy damage to your home - not to mention the effect on your health from mold growth. Pipes underneath your home's foundation could have minor leaks that could cause flooding, water damage, and higher water bills. Unfortunately, slab leaks can go unnoticed for quite a while.
In addition to wasting water, the leak can damage the concrete and erode the soil around it. Over time, it may cause the foundation to buckle and shift, cracking the home's floors and walls. In severe cases, it can even cause portions of the house to collapse.