One of the main concerns during construction is how durable and waterproof concrete blocks are. Concrete blocks usually have high strength and are water-resistant, but they are not 100% waterproof due to the porous nature of the concrete material used in them.
Concrete blocks can resist water to some extent, but they can absorb moisture depending on their composition, density and mortar joints. In this blog, we will discuss why concrete blocks are not completely waterproof and how you can make them waterproof by managing moisture.
Concrete blocks are a highly durable construction material made from cement, sand, aggregate, additives and water and are water-resistant but not completely waterproof, depending on their composition, type of block and method of installation.
The main difference between water-resistant and waterproof is water permeability. Being water-resistant means concrete blocks can resist water to a great extent but can absorb moisture, while being waterproof means they do not allow absorption at all.
Concrete blocks are not waterproof due to the porous nature of concrete material, but it is not the only factor. Some other factors can allow water to enter the concrete blocks and can weaken the overall structure.
Small voids or capillaries are left in the structure of the concrete material during curing, and these voids allow water to pass through the block.
Mortar joints usually have more pores than the blocks themselves, and with time they can create hair-like cracks, which allow excess water to flow through the structure, resulting in water leaks.
Structures outside the building, such as walls which have to face heavy rainfall or sunlight, can be weakened over time and allow excessive absorption of water along with mould growth.
Block type or density also affects water permeability. The structure of dense blocks is not so porous and has low water absorption.
Any cracks or defects in a concrete block structure can weaken or decrease the lifespan of the structure by allowing water to flow through them and seep into the structure.
Absorbed water in concrete blocks affects them both positively and negatively. The positive impact is hydration, which is essential during curing when cement, stones and aggregates are mixed, and water absorption forms a strong gel to make a durable or strong structure of concrete blocks. Negative impacts may involve:
Water dissolves the concrete and carries away some soluble components with it, which can weaken the overall structure, and with the passage of time, it can cause deterioration. It increases porosity and permeability while reducing mechanical strength.
Some concrete is strengthened by using steel reinforcement bars underneath. When water is absorbed and reaches the steel bars, it can cause corrosion. It can cause volume expansion and reduce load-bearing capacity.
This issue commonly arises in cold areas where water freezes when it enters the concrete, causing it to expand. This expansion exerts force on the rest of the concrete, which results in cracks, spalling and deteriorated structural integrity.
Water absorbed into the concrete dissolves salts and carries them with it. When water leaves the surface, it leaves them behind on the surface in the form of white deposits. It is an appearance problem but not necessarily structurally harmful.
There are different types of concrete blocks, including dense, lightweight and hollow blocks based on their density and strength. Each type has its own characteristics and is suitable for different structures.
Concrete blocks are not inherently waterproof but can be made highly water-resistant with proper treatment, such as using sealants or other waterproofing methods. For applying waterproofing methods, first remove dirt, efflorescence and any mould growth from the concrete structure.
Cement-based materials are mixed and applied to the concrete block surface, which creates a protective layer over the concrete against water. It is suitable for places with more water interaction, such as basements and foundations.
Sealants are directly applied to the surface, covering the porous spaces in the concrete block and resisting water from entering while preventing mould growth. They are suitable for areas with low pressure or internal spaces such as partition walls in the house.
Waterproof sheets are installed on the foundations, or liquid sheet membranes are applied to the concrete surface, creating a barrier to moisture and water. They are suitable for areas with more moisture exposure, such as basement walls.
Preventing moisture problems includes stopping water from entering the concrete blocks and creating a way for proper drainage. You can use these simple tips to prevent moisture problems in your concrete block wall.
A concrete block is a highly durable construction material. Although it is robust, strong and water-resistant, it is not one hundred percent waterproof. The porous structure of the concrete blocks allows water or moisture to enter them, but it depends on the block type and mortar joints.
Although concrete blocks are not completely waterproof, you can make them more waterproof by using some waterproofing methods such as applying sealants, cementitious materials and exterior waterproofing membranes. If you are looking for a reliable source for high-quality concrete, you can contact Ready Mix Concrete London.