Apr 18, 2025
Apr 18, 2025
Why Do We Recycle Cement?
Why Do We Recycle Cement?
Among the materials that can be effectively reused is recycled cement.
Why Do We Recycle Cement?
Recycling is one of the key steps toward sustainable development. Among the materials that can be effectively reused is recycled cement. This type of cement can help reduce the amount of waste generated from demolished concrete structures, whether the demolition is due to urban redevelopment for new construction with different specifications or as a result of wars and disasters that cause massive destruction.
Recycling cement also reduces the demand for raw materials typically used to produce cement from scratch, making it an important step in protecting the environment and preserving resources.
How Is Recycled Cement Produced?
Demolished concrete is burned at a specific temperature.
Experiments have shown that the optimal temperature for burning concrete is 450°C, as this is the temperature at which the greatest weight loss occurs according to TGA (Thermogravimetric Analysis).
This temperature also maintains the highest compressive strength for the new concrete produced from the recycled cement.
After burning, the concrete mass is ground to make it ready for reuse.
What Are the Properties of Concrete Made from Recycled Cement?
When using recycled cement, the resulting concrete mix can achieve compressive strength similar to that of concrete made from ordinary Portland cement (OPC), but with lower workability.
How Can We Improve Workability?
To address this issue, researchers added ground granulated blast furnace slag (GGBFS) to the concrete mix in specific ratios. This addition helped to:
Increase workability
Maintain the same compressive strength
Is Recycled Cement a Real Alternative?
Recycling cement waste can be considered a sustainable and effective method if the physical properties match those of ordinary Portland cement (OPC). Studies have shown that:
To achieve high-quality recycled cement, the demolished concrete should be no more than two years old after being crushed.
Environmental Benefits of Recycled Cement:
Lower CO₂ emissions
Lower energy consumption during production
Reduced construction waste
When Did Concrete Recycling Gain Importance?
Concrete recycling began to gain attention in the late 20th century, due to:
Increased environmental awareness
Decreased landfill capacity
Leading Countries in Recycling:
Some of the countries that effectively use recycling in the construction sector are:
Belgium
Netherlands
Denmark
These countries produce and widely use Recycled Concrete Aggregate (RCA) in their projects.
Can All Types of Aggregate Be Recycled?
Coarse aggregate (larger than 5 mm) is the most suitable for recycling.
Fine aggregate (less than 5 mm) can be used, but the concrete mix design must be adjusted to avoid issues.
What Challenges Do We Face When Using Recycled Concrete?
When using recycled aggregate, several factors must be considered:
Workability
Durability
Alkali-silica reaction (ASR)
Corrosion due to chloride content
Freeze-thaw resistance
Sources :An investigation on the recycling of hydrated cement from concrete demolition waste - ScienceDirect
Recycled cements drive down emissions without slacking on strength - Princeton Engineering
Apr 18, 2025
Why Do We Recycle Cement?
Among the materials that can be effectively reused is recycled cement.
Why Do We Recycle Cement?
Recycling is one of the key steps toward sustainable development. Among the materials that can be effectively reused is recycled cement. This type of cement can help reduce the amount of waste generated from demolished concrete structures, whether the demolition is due to urban redevelopment for new construction with different specifications or as a result of wars and disasters that cause massive destruction.
Recycling cement also reduces the demand for raw materials typically used to produce cement from scratch, making it an important step in protecting the environment and preserving resources.
How Is Recycled Cement Produced?
Demolished concrete is burned at a specific temperature.
Experiments have shown that the optimal temperature for burning concrete is 450°C, as this is the temperature at which the greatest weight loss occurs according to TGA (Thermogravimetric Analysis).
This temperature also maintains the highest compressive strength for the new concrete produced from the recycled cement.
After burning, the concrete mass is ground to make it ready for reuse.
What Are the Properties of Concrete Made from Recycled Cement?
When using recycled cement, the resulting concrete mix can achieve compressive strength similar to that of concrete made from ordinary Portland cement (OPC), but with lower workability.
How Can We Improve Workability?
To address this issue, researchers added ground granulated blast furnace slag (GGBFS) to the concrete mix in specific ratios. This addition helped to:
Increase workability
Maintain the same compressive strength
Is Recycled Cement a Real Alternative?
Recycling cement waste can be considered a sustainable and effective method if the physical properties match those of ordinary Portland cement (OPC). Studies have shown that:
To achieve high-quality recycled cement, the demolished concrete should be no more than two years old after being crushed.
Environmental Benefits of Recycled Cement:
Lower CO₂ emissions
Lower energy consumption during production
Reduced construction waste
When Did Concrete Recycling Gain Importance?
Concrete recycling began to gain attention in the late 20th century, due to:
Increased environmental awareness
Decreased landfill capacity
Leading Countries in Recycling:
Some of the countries that effectively use recycling in the construction sector are:
Belgium
Netherlands
Denmark
These countries produce and widely use Recycled Concrete Aggregate (RCA) in their projects.
Can All Types of Aggregate Be Recycled?
Coarse aggregate (larger than 5 mm) is the most suitable for recycling.
Fine aggregate (less than 5 mm) can be used, but the concrete mix design must be adjusted to avoid issues.
What Challenges Do We Face When Using Recycled Concrete?
When using recycled aggregate, several factors must be considered:
Workability
Durability
Alkali-silica reaction (ASR)
Corrosion due to chloride content
Freeze-thaw resistance
Sources :An investigation on the recycling of hydrated cement from concrete demolition waste - ScienceDirect
Recycled cements drive down emissions without slacking on strength - Princeton Engineering
