What is GGBS? Why its using in concrete?

GGBS (Ground Granulated Blast Furnace Slag) is a by-product of the iron-making industry and is obtained by rapidly cooling molten blast furnace slag. It’s used as a partial replacement for Portland cement in concrete to enhance its properties.

Some of the benefits of using GGBS in concrete include:

1. Improved durability: GGBS improves the durability of concrete by reducing the permeability of the mixture, which reduces the penetration of water and other harmful substances.
2. Increased strength: GGBS can enhance the compressive and tensile strength of concrete, making it more resistant to cracking and damage.
3. Reduced CO2 emissions: Using GGBS in concrete reduces the amount of Portland cement required, thus reducing the amount of CO2 emissions produced during cement manufacturing.
4. Improved workability: GGBS can improve the workability of concrete, making it easier to place and finish.
5. Cost-effective: GGBS is usually cheaper than Portland cement and can result in cost savings when used as a partial replacement.

In conclusion, GGBS is widely used in concrete production due to its numerous benefits and its availability as a by-product of the iron-making industry.

how to determine GGBS quantity in concrete design mix with example

The quantity of GGBS to be used in a concrete mix can be determined as a percentage of the total cementitious material content in the mix. This percentage is usually referred to as the replacement level and is typically expressed as a fraction of the cement content.

For example, if a concrete mix design requires 300 kg of cement per cubic meter of concrete and you want to use a replacement level of 50%, the required quantity of GGBS would be:

GGBS Quantity = (Replacement Level * Cement Quantity) / (1 + Replacement Level)

GGBS Quantity = (0.5 * 300 kg) / (1 + 0.5) = 150 kg

So, the concrete mix would contain 150 kg of GGBS and 150 kg of cement.

Note: The replacement level of GGBS in concrete may vary depending on the specific requirements of the project, the strength and durability specifications, and the local regulations. It’s recommended to consult with a professional engineer or concrete specialist to determine the appropriate replacement level for your specific project.

Advantage of using GGBS

Here are some of the advantages of using GGBS in concrete:

1. Improved sustainability: GGBS is a by-product of the iron-making industry and its use in concrete helps to reduce the environmental impact of cement production by reducing the amount of CO2 emissions generated.
2. Increased durability: GGBS improves the durability of concrete by reducing its permeability, which reduces the penetration of water and other harmful substances, thereby enhancing its resistance to weathering, corrosion, and other forms of degradation.
3. Enhanced strength: GGBS can enhance the strength of concrete, making it more resistant to cracking and damage, and also reducing the risk of premature failure.
4. Improved workability: GGBS can improve the workability of concrete, making it easier to place and finish, and reducing the need for additional admixtures.
5. Cost-effectiveness: GGBS is typically cheaper than Portland cement and can result in cost savings when used as a partial replacement.
6. Improved corrosion resistance: GGBS has a low alkali content, which makes concrete made with it more resistant to corrosion, particularly in aggressive environments.
7. Reduced heat of hydration: GGBS has a lower heat of hydration compared to cement, which reduces the risk of thermal cracking in large concrete structures and also makes it easier to place and finish concrete in hot climates.

In conclusion, the use of GGBS in concrete provides numerous benefits that can enhance the sustainability, durability, strength, and workability of concrete, while also reducing costs and improving performance in specific environments.