A frequent problem that occurs in many buildings is the dampening of concrete floors. Due to its porous nature, concrete slabs are susceptible to moisture from different sources.
It can be due to many reasons, but one of the most common reasons is when the moisture level is in excess, causing it to spread to the floor layer from underneath the building. Every problem can be solved by understanding the root cause to tackle it effectively.
Causes of dampness on Concrete floors
When the moisture content is surplus, it rises above and spreads underneath the concrete flooring slabs due to surface tension causing dampness. It is known as rising damp and is caused because of the capillary action that results in water rising above and reaching ground level.
Another reason for dampness to occur is when there is excess water in the concrete mix ratio. It is known as ‘free water’ in concrete which implies that the ratio between the cement, aggregates, and water is not proportionate. Thus, implicating that the clusters are not dry, and the quantity of water is more than the absorption capacity of the aggregates. Hence, free water rises towards the concrete flooring causing it to dampen.
For walls, dampness can occur due to improper design which causes the walls to be exposed directly to harsh weather conditions, leaking of pipes, etc.
The main reason behind the occurrence of this phenomenon is,
- Inadequate quality testing and inaccurate moisture level checking
- Ineffective slab moisture protection
- Wet construction sites
- Fleeting construction schedules
How to prevent moisture accumulation?
There are several methods used to prevent dampness from occurring. Here, few of them are briefly explained:
Natural drying of concrete slabs
One way to prevent damping is by allowing the concrete slabs to sit out separately in ideal drying conditions until it is completely dried. The period for drying will depend upon the thickness of the portion.
Integral Damp Proofing
This method involves the mixing of damp-proof materials to the concrete mix ratio to make it waterproof. The materials such as chalk, petroleum, fatty acids, calcium chlorides, etc… that are repulsive to water can be added in proper proportion to concrete to make it resistant to water.
Damp Proof Course (or) Membrane
This process involves adding a partition between the source causing dampness and the concrete slabs. This partition or membrane is usually made up of materials that are both water-repellent and flexible such as plastic or polythene sheets, asphalt, metal, etc. Damp Proof Course (DPC) can be used for both floors and walls.
Outer Wall Construction
A layer is constructed between the main walls and the outer structure, thereby, leaving a cavity between the two. This cavity prevents the inner walls from being exposed to moisture from the outside.
Treatment of the surface
This process involves the application of compounds that are resistant to moisture on the surface of the flooring. Moisture can find its way through cracks on the surface, and this agent can be applied in between the cracks to seal away the dampness.
The surface treatment is only efficient when the area is not under pressure. In areas where the coercion is more, this treatment may not be as effective.
Pressure Grouting
Grout is a mixture of cement, water and sand. It is usually applied in areas that are susceptible to pressure and where cracks are present. Cement grout is used to fill up these fractures that are present so that the foundation of the building is more resistant to the penetration of moisture and dampness.
