Advanced concrete technology is a constantly evolving area. Many studies, particularly on plasticizer additives, were conducted, which enabled the properties of new generation additives to develop. These developments resulted in the production of cementitious composite materials with very low water/binder ratio.
Reactive powder concrete (RPC) is a special type of high-strength concrete; RPC’s microstructure has been developed with a distinct design approach compared to conventional concrete, and its compressive strength is over 200 MPa.
High-strength aggregates that improve the properties of reactive powder concrete enable the desired high strength to be achieved. Moreover, fine steel fiber reinforcement ensures that RPC presents ductile behavior.
RPC is used abroad in the construction of structures, where aesthetic concerns stand out, permanence and impermeability are very important, long service life and high strength are required ( such as nuclear waste storages, military ammunition depots, explosion-protected military structures, etc.).
RPC designs are expected to cross larger spans with more slender elements and to enable the construction of high-rise buildings with reinforced concrete carrier systems that have thinner cross-section elements.
RPCs, which are new generation cement-based composite materials that exceed the mechanical properties of conventional and high-strength concretes, are expected to become widespread in exclusive areas of application in the future.
What are the Areas of Application for Reactive Powder Concrete?
We can summarize the areas of application and advantages of RPC as follows:
- RPC has the structural strength to compete with steel, allowing the production of delicate prefabricated elements.
- RPC has very high compressive, tensile, and shear strengths.
- RPC is an ideal composite for the production of thin shells and plates.
- RPC provides good adherence with steel fibers, resulting in high ductility and energy absorption capacity. These features give RPC the potential to enhance the performance of structures under earthquake impacts.
- RPC can last for many years. With its very low water/binder ratio (≈0.20) and minimal void content, RPC prevents the entry of water and chemicals containing harmful ions into the building element. Thus, RPC’s resistance to adverse weathering effects such as freeze-thaw and wetting-drying cycles is quite high.
RPC shows ductile behavior with fiber reinforcement. As a result, secondary reinforcement can be reduced.
In Türkiye, rainwater grill sets made of RPC were installed in Taksim-Elmadağ to test the material (Taşdemir et al., 2005). Thanks to this project, permanent components resistant to vehicle loads were produced, helping to prevent the issue of steel covers being stolen.”
Figure 1. Manhole Cover and Rainwater Grill made of RPC
One of the world’s first structures made with reactive powder concrete is the Sherbrooke pedestrian bridge in Canada (Figure-2). The bridge is a space truss made of RPC 200. In the bridge spanning 60 meters, elements made of reactive powder concrete are used in the top and bottom chords, while steel is utilized in the diagonal and web members (Blais and Couture, 1999).
Figure 2. Sherbrooke Pedestrian Bridge – Canada
Another application is the Pont du Diable footbridge in France (Figure 3). Designed by engineer Romain Ricciotti and architect Rudy Ricciotti, this single-span footbridge is 70 m long and 1.8 m wide, featuring post-tensioned beams.
Figure 3. Pont du Diable Footbridge – France
RPC can also be used in reinforcement projects. Reactive powder concrete elements, produced in the form of plates or angle sections, are applied under weak beams and at column-beam junctions to improve the performance of reinforced concrete frames.
There are research and applications regarding the use of RPC in nuclear waste storage facilities.
Thin-walled pipes that will be exposed to high pressure, thin shells and walls, defensive structures, shelters, and building components designed for long service life represent potential areas of application.
Durability is another feature in which RPC exhibits ultra performance. RPC has high resistance to the penetration of aggressive ions and water thanks to its low porosity, very low water/binder ratio, and poorly connected capillary gaps. Research reveals that the durability of RPC against adverse effects such as freezing-thawing and weathering is even higher than that of high-strength concrete.
How to Produce Reactive Powder Concrete?
The ultra-high performance (strength and durability) of RPC is a result of its dense microstructure. To form this microstructure, a distinct design approach is used during its production compared to conventional concrete. The approach is as follows:
- In order to increase the homogeneity in the concrete mixture matrix, the maximum aggregate diameter is kept very low (Dmax < 1 mm).
- In order for the mixture matrix to achieve optimum density, the amounts of the concrete components must be investigated experimentally, and the aggregate grain distribution must be selected accordingly.
- Usually, the water/binder ratio is kept very low, between 0.10 and 0.22.
- Thus, high dosages of hyperplasticizing additives are used.
- The mixture can only be prepared with high-speed mixers.
- Effective vibration is required.
- Ductility is generally increased by the use of fine micro steel wires.
- Mechanical properties are improved with the addition of high-fineness silica fume. Moreover, mineral additives with high pozzolanic activity are also used to reduce cement dosage.
- In order to ensure high strength, in addition to water curing, steam curing and autoclave curing (steam curing under pressure) are applied.
- Additionally, the strength can be further increased if it is kept under compression while in the mold during the production phase.
How to Improve Reactive Powder Concrete?
The production of new generation hyper plasticizers paved the way for the production of RPCs with very low water/cement ratio. Besides, thanks to developing microscope and microstructure research technologies, designs are supported by microstructure investigations. Thus, it is now possible to produce strong composites such as RPCs that have improved microstructures.
On the other hand, it will probably take time for RPC to be widely used in our country due to lack of standards for RPCs, having quite high costs compared to conventional concrete, and the requirement to support its production with long-term R&D studies.
References:
- Yazıcı H., Yalçınkaya Ç., “Next Generation High-Performance Concrete: Reactive Powder Concrete”, Bulletin of the Chamber of Civil Engineers İzmir Branch, No. 26-20, January 2011 – 156
- Blais, P.Y. & Couture, M. (1999). Precast, prestressed pedestrian bridge – world’s first reactive powder concrete structure, PCI journal New technology, september-october 99, 61-70.
- Richard, P. & Cheyrez M. (1995). “Composition of Reactive Powder Concretes”. Cement and Concrete Research, Volume 25, 17.
- Taşdemir, M.A., Bayramov, F., Yerlikaya, M. (2005). “Functions of New Generation Superplasticizers in High-Performance Cement-Based Composites.”, Proceedings of the Symposium on Chemical Additives in Structures” ss. 201-221, Ankara.
- Taşdemir, M. A., Bayramov, F., Kocatürk, N., Yerlikaya, M.,(2004). “New Developments in Performance-Based Design of Concrete”, Proceedings of the Concrete 2004 Congress”, ss. 24-57, Istanbul.
- Türkel, S., Yazıcı, H., Yiğiter, H., Aydın, S., Yardımcı, M.Y. (2007). “Development of Reactive Powder Concrete with Fly Ash and Blast Furnace Slag Additives” TUBITAK Project” (104I085).
- Yalçınkaya, Ç. (2009). “Investigation of Dimensional Stability at Early and Advanced Ages of High-Performance Cementitious Composites.” Preliminary Study Report for Doctoral Thesis Proposal, Department of Building Materials, Faculty of Engineering, Dokuz Eylül University”.
- Yazıcı, H., Yardımcı, M.Y., Aydın, S., Karabulut, A.Ş. (2009). “Mechanical properties of reactive powder concrete containing mineral admixtures under different curing regimes”. Construction and Building Materials 23 (2009) 1223–1231.
- Yazıcı, H., Yardımcı, M.Y., Yiğiter, H., Aydın, S., Turkel, S. (2010). “Mechanical properties of reactive powder concrete containing high volumes of ground granulated blast furnace
