News Date:2015-09-14
Blast furnace cement (BFC) is created through the addition of granulated blast furnace slag with Portland cement clinker and gypsum in cement plant. Three types are available, namely A, B and C class, which meets Standard EN 197-1:2000.
Technical benefits of using BFC
BFC is used to make durable concrete structures around the world. BFC has been widely used in Europe and increasingly in the US and in Asia (particularly in Japan and Singapore), extending the lifespan of buildings from 50 years to 100 years.
Concrete containing BFC is less permeable, has lower hydration, higher ultimate compressive strengths, is resistant to sulfate-acid attack and aggressive chemicals, resistant to many forms of deleterious attack, to alkali-silica reaction and has better workability and finish ability than normal concrete.
Concrete made with BFC sets more slowly than concrete made with ordinary Portland cement, depending on the amount of GGBS in the cement, but also continues to gain strength over a longer period in production conditions. This results in lower heat of hydration and lower temperature rises, and makes avoiding cold joints easier, but also means that quick setting is required.
The use of BFC significantly reduces the risk of damage caused by alkali-silica reaction (ASR), provides higher resistance to chloride ingress, reducing the risk of reinforcement corrosion, and provides higher resistance to attacks by sulfate and other chemicals.
Durability
BFC has now effectively replaced sulfate resistant cement (SRC) because of its superior performance and greatly reduced cost compared to SRC. BFC is more resistant against sulfate attack than Portland cement (OPC) and sulfate resistant cement (SRC) according to tests performed by Quality Control Laboratory of Turkish Cement Manufacturers’ Association (TCMA).
28-day strength loss due to the effects of sulfate was observed at 30% for OPC, at 20% for SRC and at just 18% for BFC.
Instances of chloride attack occur in reinforced concrete in marine environments and in road bridges where the concrete is exposed to splashing from road deicing salts. In most projects BFC is now specified in structural concrete for bridge piers andfor protection against chloride attack.
|
Material |
Annual consumption for PC (tpa) |
Annual consumption for BFC (tpa) |
Difference (tpa) |
|
Clinker |
1 900 000 |
837 000 |
1 063 000 |
|
Gypsum |
100 000 |
63 000 |
37 000 |
|
GGBFS |
|
1 100 000 |
-1 100 000 |
|
Total |
2 000 000 |
2 000 000 |
0 |
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