Concrete Technology Today – July – September 2011
Concrete is almost sure to crack if it is not properly placed or cured. For this reason, waterproofing concrete with a straightforward, dependable and guaranteed system offers an indispensible level of protection, particularly for dam walls with steel reinforcement. If water enters cracks in the concrete, it can damage the reinforcing steel below the concrete surface. Steel expands when it corrodes, which leads to more cracks and water ingress. Over time, the concrete deteriorates and fails, which can result in devastating floods.
Due to the extreme risk potential in building or waterproofing a dam, governments and engineers are increasingly turning to integral crystalline waterproofing manufacturers for their waterproofing needs. Integral systems can be used in either the construction or repair of a dam, and can add decades to the life of a concrete structure.
Unlike membrane systems that can deteriorate over time, integral systems become part of the concrete matrix, waterproofing from the inside out. This gives these systems added reliability over other waterproofing systems as they cannot be punctured or torn. Integral systems are not worn away by constant exposure to water, salts or other contaminants and are not affected by UV rays or concrete expansion and contraction. Also, they offer a green solution because they allow the concrete to be recycled after its useful life is over. For a green form of energy such as hydroelectric dams, integral waterproofing systems are the solutions of choice.
The Alaknanda River has always been important to the people of India. lt is a headstream of the Ganges, the holy river for followers of Hinduism and it is believed the Alaknanda split off from the Ganges when it descended from heaven. For centuries, devout Hindus have been making pilgrimages to a sacred Hindu temple in the town of Badrinath on the banks of the Alaknanda River.
The Alaknanda River has always been important to the people of India. lt is a headstream of the Ganges, the holy river for followers of Hinduism and it is believed the Alaknanda split off from the Ganges when it descended from heaven. For centuries, devout Hindus have been making pilgrimages to a sacred Hindu temple in the town of Badrinath on the banks of the Alaknanda River.
Today, the river is becoming known for the construction of the Alaknanda Dam – a 330 MW hydroelectric dam and power plant located on the riverbanks. This mega project includes a 40-m-high dam, 3-km-long headrace tunnel, and an underground penstock leading to an underground power station with two 70 MW run of river turbines.
The total head of water on the project is estimated to be 480 m when the project achieves commercial operation in 2014.
The dam and power plant is on the riverbanks just outside the town of Srinigar in Uttarakhand (formerly Uttaranchal) State in northern India. Nestled in a mountain valley, the location presents some challenges, but was chosen due to its proximity to mountain run off. lt provided the best chance to develop hydroelectricity and manage the level of the river.
The foothills of the Himalayan Mountains and surrounding scenery are spectacular. However, it is also a remote region that presents challenges to travel and year-round work schedules. Travelling to the site requires a 340 km drive from New Delhi on sometimes unreliable, winding mountain roads, which can take 12 to 14 hours in travel time. The location has snowfall for between four and six months a year, so construction cannot take place during the winter. As a result, it is anticipated construction will take about double the usual length of time to complete a project of this kind.
The region is also an active seismic zone at constant risk of earthquakes. On 8 September 1803, the area suffered a powerful earthquake that shook the whole region and devastated the town of Srinigar. As a result, the engineering and construction teams have taken noticeable steps to improve the soil stabilisation on the slopes surrounding the project area.
The region is also an active seismic zone at constant risk of earthquakes. On 8 September 1803, the area suffered a powerful earthquake that shook the whole region and devastated the town of Srinigar. As a result, the engineering and construction teams have taken noticeable steps to improve the soil stabilisation on the slopes surrounding the project area.
The town of Srinigar is also familiar with catastrophic floods. On 26 August 1894, over 10,000 million cu ft of water from the breached Gohna Lake completely swept away the original town of Srinigar. Modern day Srinigar was completely re-built by the British between 1897 and 1899. They used urban planning methodology to create a new gridiron patterned town on the upper third terrace southeast of the previous city site. The town was granted urban status in 1931 and today is a major economic, cultural and educational centre in the region.
GMR Energy started developing the dam in 2005 and Kryton International Inc. became involved in the project in 2010 after taking part in a site review meeting. Although Kryton has been involved in constructing numerous hydroelectric dams, this is the first time Kryton has taken part in the construction of a hydroelectric dam in India.
Kryton offers customers a ‘By Your Side’ service commitment with on-the-ground support every step of the way. The engineering and construction teams at this project site are making use of this offer to ensure the waterproofing system is implemented properly to ensure sustainable, lasting results. Kryton is working with the onsite ready Mix plant to optimise the mix design. Achieving the optimum mix has proved to be challenging due to the vast annual temperature fluctuation at the site. ln addition, Kryton is helping the onsite construction team to test and apply Kryton’s surface-applied waterproofing system, Krystol T1 and T2, and its internal system, Krystol Internal Membrane (KIM), to the dam face, canal, and two tunnels.
Krystol T1 and T2 have already been applied to the upstream section of the dam face, which measures 128 m by 340m. lt was applied before the monsoon season arrived in early July 2010 to provide protection from the monsoon run off in August and September. So far, the product has proven reliable in the face of heavy water exposure.
Going forward, the 1.8-km-long canal leading to the penstocks will be waterproofed entirely using KIM. Krystol T1 and T2 will be applied to the two spillway tunnels that are each 1 km long. In all, approximately 1000 tonnes of Kryton’s waterproofing systems will be used to treat tens of thousands of square metres of concrete. Using Kryton’s waterproofing system on the dam face, the canal and tunnels offer a cost-effective solution that will surpass performance requirements and ensure the dam’s concrete structure remains durable, reliable and safe for decades to come.
Much of the power generated by the dam and power plant will serve the national capital territory of Delhi, the second largest metropolitan area in India, with a population of nearly 14 million people. Ensuring a consistent supply of electricity has long been a major issue in India. Many homes and businesses throughout the country maintain gas generators to ensure a consistent supply of electricity. With India’s rapidly growing population, it is hoped this waterproofed dam will help satisfy the growing demand for power in northern India.
