Waterproof concrete mix – An overview

What is Waterproof Concrete Mix?

Waterproof concrete mix is a type of concrete designed to be impervious to water and moisture. It is created by adding waterproofing admixtures to standard concrete mix during batching. These admixtures work by reducing the capillary flow of water through the concrete.

When conventional concrete is exposed to water over time, the water can seep into the concrete and cause problems like cracking, spalling, erosion, and corrosion of reinforcing steel. Waterproof concrete mix prevents this water intrusion, making it ideal for use in wet environments or water-retaining structures.

How to Make Waterproof Concrete mix

Making waterproof concrete involves adding a waterproofing admixture to regular concrete during mixing. Common waterproofing admixtures include:

Crystalline waterproofing admixtures – These contain chemicals that react with concrete and water to form insoluble crystalline structures that plug pores and micro-cracks.
Hydrophobic admixtures – These contain waxes, soaps, and fatty acids that repel water.
Sodium bentonite clay – This swells when wet and seals concrete pores and capillaries.

Here are the key steps to make waterproof concrete mix:

Materials Needed:

• Portland cement -300 to 500 lbs per cubic yard
• Aggregate (gravel and sand) – 1200 to 1700 lbs per cubic yard(sand)
• 1600 to 2100 lbs per cubic yard(aggregate)
• Water – Around 5 to 6 gallons per bag of cement
• Waterproofing admixture – Follow manufacturer’s recommended dosage, usually 2-5% by weight of cement

1. Choose the Concrete Mix Design
   

• Use a standard mix ratio of cement, sand, and aggregate suitable for your project. A typical mix is 1 part cement, 2 parts sand, and 3 parts aggregate.

2. Add Waterproofing Admixture

• Select an appropriate waterproofing admixture. Common options are crystalline admixtures, hydrophobic agents, or sodium bentonite clay.
• The waterproofing admixture is added to the concrete mix right before or during batching. .

3. Mix the Concrete

• Mix the concrete as normal but add the waterproofing admixture along with the water. The admixture dosage is usually 2-5% by weight of cement.
• The concrete is mixed thoroughly to evenly distribute the admixture throughout the concrete

4. Mix Thoroughly

• Mix for 2-3 minutes longer than normal concrete to ensure even dispersion of the admixture throughout the concrete.

5. Transport and Place the Concrete

• Transport, place, and consolidate the concrete using standard methods. Proper curing is very important.

6. Cure the Concrete

• Concrete must be cured for at least 5-7 days and kept moist. This allows the waterproofing chemical reaction to fully occur.
• Proper concrete curing is essential to allow the waterproofing chemical reaction to fully occur.

7. Protect and Repair

• Once cured, use protective sealants and repair products specifically designed for waterproof concrete.

Following these steps will result in a high quality waterproof concrete mix suitable for a range of wet environment construction projects. Check with the admixture manufacturer for their specific recommendations.

Types of Concrete Waterproofing

There are several methods available for creating waterproof concrete. Here are the main types of concrete waterproofing:

Integral Waterproofing
This involves adding a waterproofing admixture directly to the concrete mix during batching. Common admixtures are crystalline materials, hydrophobic agents, or bentonite clay.
Surface Treatments
Applying a coating or reactive compound on the surface of hardened concrete. Examples include silane/siloxane treatments and acrylic coatings.
Membranes
Installing a sheet or liquid membrane on the concrete surface. Common options are self-adhering rubberized asphalt sheets, torch-on membranes, or cold liquid-applied membranes.
Injection
Injecting chemical grouts or resins into concrete cracks and joints. Polyurethane, epoxy, and acrylate grouts can be used.
Hydrophobic Impregnation
Impregnating the concrete surface with a hydrophobic chemical. Suitable chemicals include stearates, silicones, and silanes.
Crystalline Waterproofing
Applying crystalline slurry coatings containing chemicals that react with concrete and moisture to fill pores.
Bituminous Coatings
Applying asphalt or coal tar based coatings to concrete surfaces. Provides protection against moisture.

The choice of waterproofing method depends on factors like required water resistance, application location, cost, and project requirements. Integral waterproofing during mixing provides thorough and long-lasting waterproofing.

waterproof concrete mix vs traditional concrete

Waterproof concrete mixes typically cost more than traditional concrete, but provide added benefits that can justify the extra expense in many cases. Here’s a comparison of cost and installation requirements:

Cost:

• Traditional concrete costs $100-$150 per cubic yard on average
• Waterproof concrete can cost 15-30% more, ranging from $115-$195 per cubic yard
• Waterproofing admixtures add $2-$7 per bag of concrete mix

The increased cost of waterproof concrete is due to the special admixtures used. However, it eliminates the need for additional waterproofing steps later.

Installation:

• Traditional concrete requires no special installation steps.
• Waterproof concrete requires careful mixing to evenly distribute the admixture.
• Curing for waterproof concrete is very important and concrete must not be allowed to dry too quickly.
• No additional surface treatments are needed for integral waterproofing with admixtures.
• External membrane or coating waterproofing requires extra installation steps.

While waterproof concrete needs a bit more care during placement and curing, it simplifies waterproofing requirements overall. The admixtures provide water resistance throughout the entire concrete matrix versus just the surface. This makes waterproof concrete a convenient option for many construction needs.

Factors to consider when choosing a concrete waterproofing method

some key factors to consider when choosing a concrete waterproofing method:

• Level of water resistance needed – Determine how much hydrostatic pressure or water exposure the concrete needs to withstand. This will dictate what level of waterproofing is required.
• Location of application – Is it for below-grade foundations and basements or above-grade walls and slabs? Below-grade needs more robust waterproofing.
• New construction vs. existing structures – New structures allow integral admixtures or membranes. Existing ones may need surface treatments or injections into cracks.
• Concrete condition – Condition of the concrete surface affects what types of coatings or membranes can be applied. Cracks need special attention.
• Permeability requirements – Does the waterproofing need to still allow vapor transmission? Or total water impermeability?
• Accessibility – Some areas may not be reachable once the structure is complete. This requires integral admixtures or pre-applied membranes.
• Cost considerations – Specialty treatments can be more expensive than general coatings. Budget impacts the options.
• Ease of application – Some waterproofing like crystalline slurries are easier for do-it-yourself application than seamless sheet membranes.
• Building regulations – Waterproofing methods must conform to any required building codes and standards.

Advantages of Waterproof Concrete mix

• Prevents Water Infiltration – The primary benefit is that it stops water from entering and passing through the concrete. This prevents damage, leaks, and corrosion.
• Increased Durability – Waterproof concrete is more resistant to damage from freeze-thaw cycles, chemical exposure, abrasion, and weathering. It has a longer service life.
• Reduced Cracking – By preventing water penetration, waterproof concrete is less susceptible to cracks from weather fluctuations or ground settlement.
• Lower Maintenance – Unlike coatings or membranes, integral waterproofing with admixtures provides permanent protection without the need for reapplication over time.
• No Change in Appearance – Waterproof concrete maintains the same natural concrete look and texture. It won’t change the appearance.
• Versatile Applications – It can be used for foundations, basements, tunnels, water tanks, bridges, and other structures.
• Cost Effective – Waterproofing admixtures cost less than most other post-installation waterproofing methods. They also reduce long term repair costs.
• Improved Indoor Air Quality – Waterproof concrete prevents moisture and humidity within the structure, creating a healthier internal environment.
• Environmentally Friendly – Admixtures don’t require solvents or use toxic chemicals compared to some coating options.

Specifying waterproof concrete is a smart way to build durable structures protected from water damage and deterioration. It offers major performance and cost advantages compared to traditional concrete and other waterproofing techniques.

Waterproof Concrete mix Application

Waterproof concrete is extremely versatile and can be used in many structural applications:

• Foundations – Waterproof concrete is ideal for foundations of buildings and houses. It prevents water seepage into basements and crawlspaces from the surrounding soil.
• Retaining Walls – Retaining walls need to be waterproof to prevent moisture damage and erosion. Waterproof concrete is reliable for retaining walls that face extensive soil and water pressure.
• Bridge Decks – Bridge decks experience a lot of moisture exposure. Waterproofing the concrete prevents freeze-thaw damage, scaling, and corrosion of the steel reinforcements.
• Tunnels – Underground tunnels need waterproofed concrete to stop groundwater infiltration through the walls and base. This prevents leaks and damage.
• Water Tanks – Concrete water tanks for water storage and treatment obviously require concrete that can withstand constant water contact without leaking.
• Swimming Pools – Pool concrete needs to prevent water leakage and endure long-term exposure to pool chemicals. Waterproof concrete helps pools stay watertight.
• Dams – The concrete face and foundations of dams must be waterproof and impermeable under extreme hydrostatic pressure. Waterproof concrete is essential.
• Bathrooms – Bathroom concrete floors and walls benefit from waterproof properties to prevent moisture damage and mold growth.
• Balconies – Balcony concrete needs waterproofing to stop rain and melted snow from penetrating into the building below.
• Marine Structures – Concrete for docks, seawalls, and other marine environments needs integral waterproofing to resist damage from saltwater.

Conclusion

Waterproof concrete mix has emerged as an incredibly useful innovation in construction and civil engineering. The ability to integrally waterproof concrete during the mixing process provides lasting protection and durability to concrete structures.

As construction expands in wet regions and densifies with below-grade structures, waterproof concrete mix will become even more valued. Specifying a waterproof concrete mix is a reliable way to save costs in the long run by avoiding water damage. With the many advantages over conventional methods, waterproof concrete is poised to become the new industry standard where water exposure is a risk factor.