Integral Watertight Concrete Structures- An Insight

Integral Watertight Concrete Structures- An Insight

Upen Patel, Marketing Manager, BASF Construction Chemicals (India) Pvt. Ltd. Mumbai

Preface

Since the Stone Age mankind has struggled to keep the structures watertight, Even today’s struggle is on to deploy one or other kind of waterproofing system to achieve total water tightness of structures. In spite of good construction practices at site and using branded products, engineers struggle to keep structures watertight. So far the approach has been based on achieving watertight tanking around the structure to guard entry of water in the structure; less attention and focus has been on getting integral water tightness (within the structure). This article explains the main sources of leakages in the structure, and using two technological advancements to enable integral water tightness to structure with a live case study.

Sources of Leakage

There are three main sources of water leakage in concrete structures:
  • Construction Joints
  • Cracks
  • Porous media

Construction Joints

Large structures of concrete are cast in number of sections. The dividing lines between two sections are the joints between already harden concrete and freshly poured concrete, with continuity of reinforcements. At these joints fresh concrete shrinks and creates a fine crack. These cracks are normally 0.1 – 0. 3 mm in width and are passages for water to pass through the structure.

Cracks

Integral Watertight Concrete Structures- An Insight
Due to various reasons such as excessive segregation of concrete mix, high water cement ratios, movements, settlements, rapid variations in ambient temperatures, early de-stripping, etc… concrete structures develop cracks during the construction stage and these cracks are some time deeper and can easily transport water from one side to another.

Porous Concrete Media

Concrete has heterogeneous matrix, a mixture of binding paste and fillers. While mixing the ingredients and placement of fresh concrete, concrete entraps air and the same is attempted to remove by compaction using mechanical means. Achieving uniform compacting throughout the volume of freshly placed concrete is very difficult to achieve. In adequate compaction results in to the air voids. Theoretically, concrete requires only 23 – 25% water by weight of cement for the chemical hydration of the cement. While actual concrete in practice contains 40 – 50% of water by the weight of cement. The extra water is provided to achieve desired workability and easy of placement. This extra water leaves the concrete mass during the hydration reaction resulting in to the formation of pores. An interconnected series of such pores are popularly known as capillary pores. These capillaries make concrete porous. Besides these two features concrete also contains hydration pores which are formed due to volume changes of hydration products and are normally filled with loose lime, one of end product of the hydration reaction. These hydration pores promotes diffusion of corrosive agents in the concrete.

Integral Watertight Concrete Structures- An Insight

The Integral Watertight Solution

To check the porosity of concrete and leakages through the joints & cracks, integral watertight concept is gaining popularity. The concept is a combination of two systems:
  • Watertight joints using reinjectable hoses
  • Watertight concrete mass by deploying self–compacting concrete concept

Re-injectable Hoses

Integral Watertight Concrete Structures- An Insight
The re-injectable hoses are made up of PVC plastic core which enables toughness to the hose. The core has injection channel in the centre, which connects to openings at regular distance in all four directions. The openings are guarded with neoprene seals.
Integral Watertight Concrete Structures- An Insight
The hose is placed at the central line of the construction joints using clips and the ends are connected to nonperforated hose with termination in near-surface mounted junction boxes. After the casting and destripping of the concrete cover of the junction box is located and marked for future operations. Each length of the hose is first injected with water to assess the leakages at the construction joint. Then injected using water–based lowviscosity, re-swellable, vinylacrylate injection resin. The injection resin pressurized the soft neoprene seals and squeeze out around seals to the openings and travels around the hose and to the crack of the construction joints and other cracks which connects to the construction joints. In the next stage of operation, injection pressure is release and the hose is applied with the vacuum. The neoprene seals now gains original size and seals the openings and prevents the suction of resin from outside of the hose to inside. Also all the resin from the central channel is sucked out and then the hose is rinse using water under low pressure re-circulation stage. Now the resin in the cracks has set and forms an effective seal for passage of water in the future. The hose can be injected with water to verify the effectiveness of the injection. If leakages are noticed then the hose is re-injected with the resin once again. Overall the re-swellable acrylate resin and injection hose provides following main benefits:
  • Re-injectable hose – permanent access to the construction joint
  • In-build QA system–Test the effectiveness by injecting with water
  • Re-swelling injection resin– swells up to 2.5 time in volume to maintain tight seal even in the case of movements in the cracks

Watertight Self– compacting Concrete

To obtain proper, robust self– compacting concrete, it is important to include all of following components in the mix. These components enhance the performance of the fresh concrete as mentioned below:
  • Hyperplasticiser–which is based on PCE polymer and have 30 – 40% water reduction capabilities
  • Viscosity Modifying Agent – Improve the shear resistance and thickens the paste to achieve effective segregation resistance
  • Pozzolans – Facilitate increase in the paste volume without increasing the temperature of concrete and enables segregation resistance.
Integral Watertight Concrete Structures- An Insight
Hence, to achieve a robust mix of self–compacting concrete, it is must that all of these three ingredients are present and are properly included to maximize the benefits they can offer on the hardened properties of the mix.

From the water tightness and durability aspects—these three ingredients enable the following benefits:

Overall by carefully implementing a proper self– compacting mix, achieving watertight concrete mass is possible. Also in the case of large projects, developed mix can be tested for permeability to standards such as DIN 1048 and that can be one of the acceptance criteria. While in the case of smaller projects such special self– compacting mix can be supplied by Ready mix producers who can design and control the ingredients.

Following case history of Hercules Harbor in Monaco enables us an insight in one of such successful implementation of this integral watertight concrete concept.

Case History– Hercules Harbor

Client–Gouvernement of Monaco Location of site–Algeciras Spain Contractor–DRAGADOS BEC V Engineering–DORIS Engineering France R & D–Institute Francais du Petriole Norwegian Technical Institute and many others Technology Supplier–BASF CC Spain (BETTOR MBT)

New studies were made in the 1980‘s to protect and extend the existing harbor. The depth of the sea–bed of 55 meters did not allow conventional construction. Further the Government decided to minimise the impact for the environment during construction. Based upon studies made in France and Norway the Monaco Government decided to build a prefabricated “ semi floating seawal l” a technique common in the offshore oil industry.

Integral Watertight Concrete Structures- An Insight

The structure was 352 metres long, 44 m wide and about 35 m tall; its design required 2,900 MT of steel cables for stressing and 45,000 of concrete!

As the structure cannot be constructed in-situ and also near by area was not available for precasting yard, Engineers from DORIS Engineering decided to construct in a dry-dock, 1200 km away in Spain. As such long structure cannot be transported on the ship; it required to be floated in sea and to be transported by towing. This required total watertightness of the structure and all the joints it has.

Any leakage at joint or within the concrete mass would make it sunk below the ocean.

Based upon the construction of TROLLE, an off shore platform built in Norway, DORIS Engineering recommended the use of Self–compacting Concrete. To secure the construction joints, Masterflex 900, the re-injectable hose was specified allowing testing joints and injecting and re-injecting with resin where necessary.

After the construction all the joints were injected using Masterflex 801, water based reswelling resin and tested for watertightness.

No form of external waterproofing treatment was carried out for this structure. No membrane or no accidental drill and grouting were implemented.

Finally, the structure was towed in the sea as it can be carried on the ship and was positioned at the final location in 2004.

Conclusion

Integral Watertight Concrete Structures- An Insight
The new age technologies and quest of civil engineers have lead to solutions which are long lasting. Such implementations make these technologies time tested and real for the rest of the world to get inspired and to implement.


NBM&CW September 2007

No comments yet, Be the first one to comment on this.

Advancing Concrete Durability in Coastal and Aggressive Environments

Advancing Concrete Durability in Coastal and Aggressive Environments

Professor (Dr.) S B Hegde provides a thorough examination of the challenges faced by concrete infrastructure in India’s coastal and harsh environments; the impact of salt, humidity, pollution, and extreme weather on concrete durability

Read more ...

Concrete Distress Maintenance & Repair Techniques

Concrete Distress Maintenance & Repair Techniques

Concrete structures deteriorate over time due to environmental factors, leading to issues like cracks and corrosion. Effective repair and maintenance are vital for restoring strength and durability. In this article, Sasanka Dey

Read more ...

Durability and Sustainability of Hardened Concrete

Durability and Sustainability of Hardened Concrete

Concrete is widely used in construction, yet its longevity and sustainability often go unnoticed until signs of premature deterioration appear. To truly understand how to extend its service life, it is crucial to explore the factors

Read more ...

Role of Chemical Admixtures in Enhancing Construction Durability

Role of Chemical Admixtures in Enhancing Construction Durability

“In modern construction, the integration of chemical admixtures is not just an enhancement—it's a necessity. By improving durability, performance, and sustainability, these innovations are shaping the future of infrastructure.

Read more ...

ICrete by Amazecrete: A Game-changer Concrete Additive

ICrete by Amazecrete: A Game-changer Concrete Additive

With the introduction of ICrete, we are pushing the boundaries of concrete technology with solutions that address both performance and environmental challenges. Kowshika V R, Executive Director, Amazecrete

Read more ...

Grinding Aids as Energy Saver in Cement Production

Grinding Aids as Energy Saver in Cement Production

The benefits of using different grinding aids in cement production are improved output, decreased energy consumption, cost reduction, and minimizing the carbon footprint- all of which are steps forward in bringing greater sustainability

Read more ...

Thermax Acquires BuildTech to Expand its Footprint in Construction Chemicals

Thermax Acquires BuildTech to Expand its Footprint in Construction Chemicals

The recent acquisition of BuildTech by Thermax exemplifies a significant trend within the industry towards strategic expansion and enhanced capabilities in construction technologies.

Read more ...

Icrete By Amazecrete Enhances Strength & Durability of Concrete

Icrete By Amazecrete Enhances Strength & Durability of Concrete

Icrete has emerged as a new age material for Concrete Construction given its efficacy in increasing the strength and durability of concrete, bringing value additions and greater profitability to the users.

Read more ...

Cement Industry Targets Net Zero with 25% Emissions Reduction by 2030

Cement Industry Targets Net Zero with 25% Emissions Reduction by 2030

The Cement Industry is embarking on a Net Zero pathway, aiming for a 25% reduction in CO2 emissions by 2030 and a full decarbonization by 2050, driven by technological innovations, use of alternative raw materials, and circular economy

Read more ...

Determining Plastic Hinge Length in Precast Seismic Force-Resisting Systems

Determining Plastic Hinge Length in Precast Seismic Force-Resisting Systems

Plastic hinges form at the maximum moment region of reinforced concrete columns. A reasonable estimation of the plastic hinge length is key to successfully modeling the lateral load-drift response and conducting a proper seismic

Read more ...

Properties and Applications of Geopolymer Masonry Blocks

Properties and Applications of Geopolymer Masonry Blocks

Radhakrishna, Professor and Head, Department of Civil Engineering, RV College of Engineering, Affiliated to Visvesvaraya Technological University, Bengaluru. Block masonry is one of the oldest methods of construction. It is composed

Read more ...

Advancing LC3 Cement Technology for Sustainable Construction in India

Advancing LC3 Cement Technology for Sustainable Construction in India

Dr S B Hegde provides a deep, research-driven analysis of LC3 cement, emphasizing its chemistry, process innovations, global applicability, and success stories, and evaluates its technical advantages, performance, cost savings

Read more ...

Supplementary Cementitious Materials Improving Sustainability of Concrete

Supplementary Cementitious Materials Improving Sustainability of Concrete

Concrete is the second most consumed material after water in the world and cement is the key ingredient in making concrete. When a material becomes as integral to the structure as concrete, it is important to analyze its environmental impacts.

Read more ...

Alite & Belite in Portland Cement: A Key to Sustainability & Strength

Alite & Belite in Portland Cement: A Key to Sustainability & Strength

Dr. S B Hegde guides construction industry stakeholders on balancing cement’s early strength with long-term durability and sustainability and advocates optimized cement formulations and supplementary materials for more resilient infrastructure

Read more ...

Amazecrete: Offering Sustainable Concrete Solutions like ICRETE

Amazecrete: Offering Sustainable Concrete Solutions like ICRETE

V.R. Kowshika, Executive Director, Amazecrete, discusses the economic and environmental benefits of eco-friendly and sustainable products like ICRETE and the positive impact on the construction industry.

Read more ...

Admixture-Cement Compatibility For Self-Compacting Concrete

Admixture-Cement Compatibility For Self-Compacting Concrete

An admixture is now an essential component in any modern concrete formula and plays a significant role in sustainable development of concrete technology. Dr. Supradip Das, Consultant – Admixture, Waterproofing, Repair & Retrofitting

Read more ...

Amazecrete's Icrete: New Age Material for Concrete Construction

Amazecrete's Icrete: New Age Material for Concrete Construction

By maximizing the durability and use of supplementary cementitious materials, Icrete has emerged as a new age material for Concrete Construction V. R. Kowshika Executive Director Amazecrete

Read more ...

Nanospan’s Spanocrete® Reduces Cement & Curing Time in Fly Ash Bricks

Nanospan’s Spanocrete® Reduces Cement & Curing Time in Fly Ash Bricks

Hyderabad-based Ecotec Industries is a leading manufacturer of fly ash bricks and cement concrete blocks in South India under the trademark NUBRIK. Their products are known for their consistency and quality. Ecotec was earlier owned

Read more ...

Ready-Mix Concrete: Advancing Sustainable Construction

Ready-Mix Concrete: Advancing Sustainable Construction

A coordinated approach by the government, industry stakeholders, and regulatory bodies is needed to overcome challenges, implement necessary changes, and propel the RMC sector towards further growth such that RMC continues to play a vital

Read more ...

To get latest updates on whatsapp, Save +91 93545 87773 and send us a 'Saved' message
Click Here to Subscribe to Our eNewsletter.