Gulf Construction Online - Waterproofing holds key to durability

Precast Concrete

A section of unprotected precast concrete ... showcasing the risk of corrosion if concrete is not properly protected.

Waterproofing holds key to durability

01 October 2015

ALIREZA BIPARVA* of Kryton International highlights that while precast concrete holds the key to the quality of structures, effective waterproofing ensures their durability.

Infrastructure construction is booming at a global level, but few places are building at such a furious rate as the Gulf region.

According to a report from the Economist Intelligence Unit, the GCC has one of the fastest growing populations in the world. In fact, by 2020 it is forecasted to grow by one-third of its current population to 53 million. This means the construction industry is also rapidly growing to meet the needs of its citizens, present and future. Further, with population being centered around cities, infrastructural development in these areas is booming.

With this growing population, there is a paradigm shift in how concrete structures are being built. Sustainable development is emerging as the new regional impetus, and the desire to ensure the long-term durability of structures is gaining traction where cost used to be a reigning factor.

Throughout the Gulf region in particular, there has been an increasing demand for precast concrete, rather than the traditionally used cast-in-place concrete, in building new infrastructure. A notable benefit specific to the GCC region is that these precast forms can be created in a controlled environment, and out of the hot, humid Gulf weather. This improves quality in production and construction as the concrete is less vulnerable to weather conditions, and facilitates rapid on-site construction.

Precast concrete products have been popular throughout the world for many years. For projects where tight tolerances and dimensional accuracy are paramount, using precast concrete facilitates the construction process. Construction efficiency is increased, without compromising the integrity of the concrete, and at the same time, on-site labour, waste, noise and disturbance are all reduced significantly.

While precast concrete has been an excellent solution to building quickly and accurately, the durability factor is not solely reliant on the quality of the concrete, nor is it reliant on the application and construction of these pieces.

Krystol chemicals create a reaction that causes long, narrow crystals to form, filling the pores, capil-laries and hairline cracks of the concrete mass.

According to statistics worldwide, the ingress of water and water-borne chemicals is the greatest threat to early concrete deterioration.

Waterproofing concerns may not be front of mind in arid regions such as the Gulf, but the fact is that many of the Gulf’s major cities are being built on the coastline. These projects have precast infrastructure, such as pipes or tanks, which are constructed several meters deep into water tables close to sea level. These projects often face constant, extreme hydrostatic pressure that could cause leaks if any weakness in the structure is present. Even above-grade exposed precast products such as bridges are vulnerable to premature deterioration. These elements are exposed to the weather, water and chemicals during their service life.

Most of the mechanisms attacking concrete structures need water. The penetration of water into concrete is a critical factor in the corrosion of steel reinforcement. This corrosion can call for major repairs or even replacements to structures only a few years after initial construction, as the core of the structure is weakened.

As a porous material, concrete can allow water to migrate through it, bringing in harmful chemicals, causing short- or long-term issues that require serious attention. This is why a reliable waterproofing system is vital for a durable precast product. Overall, by ensuring a durable structure that can last for generations, the resources can be used to fuel growth rather than repair.

Using a crystalline admixture, such as the Krystol Internal Membrane (KIM) concrete waterproofing admixture, as the concrete waterproofing solution in high-value precast items such as pipe manufacturing, beams or vaults, adds a critical layer of defence to mitigate the risk of early deterioration.

When KIM is added to concrete, Krystol chemicals create a reaction that causes long, narrow crystals to form, filling the pores, capillaries and hairline cracks of the concrete matrix. As long as moisture remains present, crystals continue to grow throughout the concrete. Once the concrete has cured, the crystalline chemicals sit dormant until another dose of water (such as through a new crack) causes the chemical reaction to begin again.

The ability to reactivate in the presence of water gives Krystol-treated concrete the ability to improve and protect it during the service life of the structure. When cracks form due to shrinkage, settling, seismic activity, etc, water entering through them causes new crystals to form and grow, blocking and filling the cracks. The unique and most effective feature is its ability to improve the self-sealing ability of concrete, which can help to dramatically reduce the long-term maintenance and repair costs of a concrete structure.

Using precast concrete facilitates the construction process.

KIM crystalline admixture brings many long-term values to projects in areas where high hydrostatic water pressure is a major concern. KIM allows developers to build structures that are resilient, durable and sustainable by replacing the need for an external waterproofing membrane. Using KIM reduces the risk and potential liabilities on clients and stakeholders with technology that transforms the concrete into a waterproof barrier.

Further, KIM technology is the category leader and is the only PRAH (permeability reducing admixture for hydrostatic conditions), a feature which – according to the American Concrete Institute (ACI), the world’s leading concrete authority – is the only type of admixture that will effectively protect against hydrostatic pressure. Ensuring structures are built to withstand hydrostatic pressure is key to constructing sustainable buildings that will have a long lifespan in the Middle East. KIM decreases the lifecycle costs of any given structure by making sure costly repairs are avoided throughout the life of the building.

The long-term value in the Gulf region is great — the market is booming. As the GCC moves toward developing innovative, more sustainable building practices, increasing the durability of the materials used will ensure these iconic structures achieve the longevity they are designed for.

* Alireza Biparva is research and development manager/concrete specialist at Kryton International, the inventor of the crystalline waterproofing admixture. The Canada-based company develops, manufactures and markets products that waterproof, repair and protect concrete structures.