What is a Reactive Powder Concrete?
Reactive powder concrete (RPC) is the ultra-high strength concrete prepared by replacing the ordinary aggregate of normal concrete with quartz powder, silica fume, steel fibers etc. RPC not only has high strength but also has high ductility. Its compressive strength ranges from 200 Mpa to 800 Mpa.
Composition of Reactive Powder Concrete
Reactive powder concrete contains Very fine powders like cement, fine sand, quartz powder of size less than 300 micron, silica fume, 1 cm length steel fibers of size 180 microns and super plasticizer. Typical Composition of ingredients in Reactive powder concrete of 200 Mpa and 800 Mpa are tabulated below.
Table 1: Typical Composition of RPC of 200 Mpa
|OPC ( Type V)||955|
|Fine Sand (150 – 400 micron)||1051|
Table 2: Typical Composition of RPC of 800 Mpa
|OPC ( Type V)||1000|
|Fine Sand (150 – 400 micron)||500|
|Ground Quartz powder (4 microns)||390|
Functions of Ingredients of Reactive Powder Concrete
Functions of each of the ingredients and their selection parameters are discusses below. The ingredients of reactive powder concrete are
- Quartz Powder
- Silica Fume
- Steel Fibers
- Super Plasticizers
- Ordinary Portland cement of medium fineness is suitable for making RPC. The Cement particle size should be 1 micron to 100 microns.
- The function of cement is to act as binding material and also to generate primary hydrants of concrete.
- Optimum percentage of principle minerals or Bogues Compounds required to make RPC are tabulated below:
Table 3: Optimum Percentage of Principle Minerals of Cement
|Tricalcium Silicate (C3S)||60%|
|Dicalcium Silicate (C2S)||22%|
|Tricalcium Aluminate (C3A)||3.8%|
|Tetra-calcium Alumino Ferrite (C4AF)||7.4%|
- Natural river bed or crushed sand of particle size 150 to 600 micron is recommended.
- It should be of good hardness and readily available at low cost.
- In reactive powder concrete, sand particles are highest sized particle hence, their function is to give strength to the concrete mix.
3. Quartz powder
- Generally quartz powder is available in crystalline form. It is selected based on its fineness.
- The particle size should be 5 microns to 25 microns.
- The main function of quartz is to give maximum resistance to the concrete against heat.
4. Silica Fume
- Silica fume is generally obtained from ferrosilicon industries. It should be selected in such a way that it should contain less quantity of impurities in it.
- The particle size of silica fume is about 0.1 micron to 1 micron.
- Its function is to fill the small voids and also to enhance flow properties of concrete.
- It also helps to generate secondary hydrates in the concrete.
5. Steel Fibers
- Steel fibers of length 13 to 25 mm and 0.15 to 0.2 mm diameter are selected to prepare reactive powder concrete.
- It improves ductility of the concrete.
6. Super Plasticizer
- Polyacrylate is used as super plasticizer in RPC.
- The main function of polyacrylate is to decrease the water cement ratio and also to improve the workability of concrete.
Advantages of Reactive Powder Concrete
Following are the advantages of Reactive powder concrete compared to other types of concretes.
- Due to its High ductility property it always compete with steel.
- Fine ingredients makes the concrete void proof and no leakage of gas or liquid occurs.
- There is a reduction of dead load of structure due to higher shear capacity along with superior strength.
- RPC members have great resistance against seismic forces.
Limitations of Reactive Powder Concrete
Reactive powder concrete also have some limitations which are as follows:
- Aggregate replacing materials used in RPC are slightly expensive which increases the project cost.
- Optimization of principle minerals in concrete also increase the cost of concrete.
- Long term properties of reactive powder concrete are not known since it is still in developing stage.
- There is no official code provided for Reactive powder concrete mix design.