Waterproofing for every space

Introduction

Water ingress in concrete structures damages the structural strength, aesthetics, flaking and causes rusting of the steel reinforcements affecting the durability of the structure. Structural engineers have always been in the lookout of various protection mechanisms to restrict the passage of water and increase the life of the concrete structure. A careful analysis of these surfaces and the environmental conditions these areas are subjected to is essential to recommend a waterproofing system which can protect the substrate for years.

History of concrete

Concrete was first used by ancient Greeks/Romans back in 800 – 300 BC and was used in the construction of large arches, vaults and domes. The largest unreinforced concrete dome in the world was built by the Romans. Concrete as on date is the most used material in the world in terms of overall volume. In fact, concrete is used twice as much in construction than any other building material.

Constituents of concrete

Concrete is a mixture of graded aggregates (varying from coarse to fine), cement, water and additives. Each of these constituents offers various functionalities to the final product.

“Cement” and “Concrete” are not the same though the terms are often used interchangeably.

Limitations of concrete

While concrete has the various advantage of being available locally in abundance, economical, hardens at ambient temperatures, ease of casting into various shapes, high productivity; it can be susceptible to environmental degradation. Concrete is by design is a porous material and water can pass through it under influence of hydrostatic pressure, water vapour gradient or capillary action. Water can also enter cracks, structural defects or at improperly designed or installed joints. This can adversely affect the structural strength, life and aesthetics of the structure

Strengthening concrete

While reinforcement bars are extensively used in modern construction, pollutants like carbon-di-oxide (CO2), sulphur-di-oxide(SO2) get absorbed by rainwater and the resultant acid rain reduces the pH of concrete and starts degrading the concrete. As the pH of concrete drops below 9.5, the reinforcement bars start corroding which results in spalling i.e flaking of concrete. Further water ingress also affects the durability of the structure and this can also lead to the growth of fungus algae leading to health concerns. All these things make waterproofing a key point to be considered in any structural design of any structure.

Basically any area which may come in contact with external environment and water need waterproofing treatment. Let us look at this with an example.

A waterproofing system consists of various layers like a primer, a rigid or a flexible waterproofing membrane (based on anticipated surface movements), glass fibre mesh, protective coat. Based on the aggressiveness of the environment thickness of each of these layers may have to be increased, decreased or completely eliminated.

For zeroing upon the correct system following factors must be considered

• Conditions the particular area would be subject to (indoor/outdoor/basement)
• Accessibility of area in future
• Hydrostatic pressure
• Environmental conditions in the application area
• Temperature variation
• The criticality of that particular area
• Desired longevity (life) of the waterproofing system

Since all these factors vary significantly, a particular product or a system cannot suit these requirements in total. Hence, it is advisable to consult a company representative/expert before going ahead with any waterproofing system. Keeping the product data sheets of the product is also recommended to understand the limitations and precautions of any product.

Finally, it is equally important to have a good applicator who does necessary surface preparation and adheres to the recommended guidelines while laying any waterproofing system.