Hydraulic cement is a remarkable construction material that is widely used to address water leakage and repair damaged concrete structures. It possesses unique properties that allow it to react chemically with water, resulting in the formation of a solid, water-resistant surface. Its quick-setting nature makes it highly effective for sealing cracks and leaks in concrete and masonry work.
One of the key advantages of hydraulic cement is its ability to set rapidly through hydration, making it an ideal choice for waterworks and situations where structures are submerged in water. It is composed of a mixture of limestone, gypsum, and clay, which are burned at high temperatures to produce a cement that is resistant to rust, corrosion, and shrinkage. This durability factor has contributed to its popularity in repair and construction projects worldwide.
What Is Hydraulic Cement?
Hydraulic Cement is a product mainly used to stop water and leakage in concrete and masonry work. It sets very quickly by chemical reaction with water (hydration) and gets solidified with the immersion of water.
It has the capability to react with water under ambient conditions to form a solidified and water-resistant surface. The hydration reaction in cement results in the formation of a strong solid mass.
Hydraulic cement is made up of premium properties like using rusting proof, corrosion, and shrinkage resistance, which is making it popular all around the world for repair works.
This cement is generally used to seal water leakage and set quickly when used for waterworks. Hydraulic cement has properties to get set within 5-10 min of water mixed in it.
This is a type of cement mostly used to seal the water leakage in concrete structures and also a place where a structure is submerged into a water body.
It is a type of cement that is similar to mortar. It is generally utilized for sealing the structures and in conditions where structures are submerged in water.
It is made with limestone, gypsum, and clay, which is burned at high temperatures and primarily used to close cracks and leaks in concrete, especially those structures that have weakened with age.
Read More: How to Check Quality of Cement on Construction Site
How to Mix Hydraulic Cement?
Before the mixing process of cement, some initial preparation should be done which is discussed below,
Preparation of the surface on which cement mix is to be applied:
- The surface to be repaired and on which the hydraulic cement mix is to be applied should be clean and dust-free. Oil, grease, dirt & loose particles will prohibit the cement from adhering to the surface adequately.
- It is necessary for the temperature to be maintained between 45 F° (7℃) and 90 F° (32℃) during initial curing since the cement will not be durable on the frozen surface.
- The area should be saturated for 24 hours before applying cement there on the surface. Small cracks on surfaces & holes should be enlarged before the application of cement. V-shaped cuts are to be avoided.
Mixing of Hydraulic Cement
A mechanical mixer with rotary blades is recommended for mixing the cement to get a uniform mix. The mechanical mixer should be saturated properly and drained of extra water before mixing.
Following the specification and instruction as per the IS 456:2000, the required amount of water is to be added to the dry mix by referring to the grade of concrete. However, one time it begins to harden, more water should not be added to the mix.
It is recommended that small amounts of cement be mixed at a time since it hardens very quickly and has to be placed within 10-25 minutes.
The concrete mix should be ground at a relatively low speed.
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Chemical Composition of Hydraulic Cement
The four main chemical constituents of hydraulic cement are listed below:
- Belite (2CaO·SiO2)
- Elite (3CaO·SiO2)
- Tricalcium aluminate (3CaO·Al2O3)
- Brownmillerite (4CaO·Al2O3·Fe2O3)
The chemical properties of cement are produced by silicates (belite, Alite) whereas the last two chemicals are essential for the liquid phase in the production process inside the kiln.
In hydraulic cement manufacturing, some admixtures are also added to impart premium properties like shrinkage resistance, reduction of curing time, and setting time, to be easily used in underwater concrete structure construction.
The working principle of hydraulic cement relies on the cement hydration process which means the cement mix hardens when water is added to it.
Some chemical agents present in hydraulic cement state the reactions due to the application of water, which causes the mixture to set & harden very quickly reducing the curing time of cement mix.
The properties of these chemical agents make hydraulic cement impervious to water damage and prevent the repaired surface from chemical attacks.
Therefore, This cement is mostly used for concrete construction work which is submerged in a water body or in contact with the seawater.
Another special property of hydraulic cement is its strength against shrinkage and effloresces. Tricalcium silicate & Dicalcium silicate existing in such type of cement cause the following chemical reactions after the addition of water in cement,
Tricalcium silicate +water→ calcium silicate hydrate +other chemical products
Dicalcium silicate+water→ calcium silicate hydrate+other chemical products
After these reactions, calcium silicate is the prime product, which has a network of short fibers that enhance the strength of the cement mix greatly and also make the surface water-tight.
Suitability of Hydraulic Cement for Construction
The right kind of cement is to be chosen based on the construction nature and development work. Various mixes of hydraulic cement contain changing proportions of chemical components to suit specific necessities.
This cement is preferable in a construction project where the speed of construction matters. In such a case, hydraulic cement provides less curing time and setting time cement which makes work faster.
However, it just gives a short window of time to work with it before it solidifies. Hydraulic cement is only suggested where the concrete mix is going to be used within 10-15 min of the time period.
This cement is capable to provide strength to structures that are in contact with water. Therefore, hydraulic cement is used for concrete structures which are highly durable in nature.
How to Use Hydraulic Cement
The following is the procedure to follow while applying hydraulic cement
- The first step of hydraulic cement application is clean the damaged surface with a wire brush.
- Make sure the surface where hydraulic cement is to be applied is not infected with oil and dirt otherwise cement mix will not form a proper and strong bond with the surface.
- The repaired surface must be saturated with water at least 24 house before hydraulic cement is to be applied to it.
- Try to use a mechanical mortar mixture to form a proper mix of hydraulic cement with water.
- Mix water in hydraulic cement as per supplier guidance.
- Any excess water left in a mix should be removed before application
- Now, apply hydraulic cement for repair work where it is required.
Precaution While Using Hydraulic Cement
The hydraulic cement mix should be applied on the surface as fast as possible.
Excessive blending/mixing will cause bleeding and segregation.
Some other admixtures or additives should not be added except if mentioned in the manufacturer’s instructions.
For constructing underwater structures, hydraulic cement has particularly no other alternative option. Being impermeable to water, it is very well utilized in constructing structures that are in steady contact with water.
This type of cement mix doesn’t corrode or rust, hence consequently it holds its strength even when submerged in water. It is also incredibly useful for water sealing.
Hydraulic Cement Uses
Hydraulic Cement is very useful for the following construction:
- Footings and foundations
- Heavy Construction
- Levee walls, sea walls, retaining wall
- Bridges, culverts
- Monolithic concrete houses, concrete block
- Tower structures
- Dams and breakwaters
- Irrigation ditches, filter beds
- Fireproofing structures
- Chimneys and sewer pipes
- Road foundations paved roads, sidewalks
- Tunnels and prison cells
Advantages of Hydraulic Cement
- To use hydraulic cement no special skills are required.
- Hydraulic cement is set too quickly which helps in achieving desired strength as early.
- This cement has premium properties like shrinkage resistance and corrosion resistance.
- Hydraulic cement is most water resistant and can be used for underwater construction work.
- It is proven to be economical for repair work compared to other chemical products in the market.
- It is mostly recommended to be used for long-lasting concrete structures.
- It is used for sealing minor concrete cracks in the basement and various concrete damage surface cracks.
Disadvantages of Hydraulic Cement
- Its major disadvantage is that it has to be used within 10-15 min after water is added to the cement. It means it sets very quickly compared to others.
- Hydraulic cement is not recommended to be used in the frost-affected area.
- This cement is not flexible in nature. therefore it only offers mechanical strength of the structure.
- It cannot be utilized in areas where the temperature is below 48°F.
Conclusion:
Overall, Hydraulic cement is a modern invention that reacts with water chemically to gain strength and form a hardened surface.
Due to its unique properties, it is mostly used across all forms of construction. Hydraulic cement does not shrink or contract like ordinary cement, and a few mixes even develop solidifying.
FAQs:
What is batching of concrete?
Batching of concrete refers to the process of measuring and combining the ingredients required for making concrete, such as cement, aggregates, water, and admixtures, in specific proportions to achieve the desired concrete mix.
Why is accurate batching important in concrete mixing?
Accurate batching is crucial in concrete mixing because it ensures consistency in the proportions of ingredients, resulting in a uniform concrete mix with the desired strength, durability, and workability. Inaccurate batching can lead to issues such as weak or brittle concrete, variations in strength, and poor performance.
How can I ensure accurate batching of concrete?
To ensure accurate batching of concrete, it is essential to use calibrated weighing equipment, follow the specified proportions of ingredients as per the concrete mix design, properly maintain the batching equipment, and conduct regular checks and adjustments to eliminate any errors.
Can batching errors be corrected?
Batching errors can be corrected, but it is best to avoid them in the first place. If errors are detected, adjustments can be made by adding or subtracting specific ingredients to achieve the desired proportions and maintain the consistency of the concrete mix.
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