Concrete deterioration research

The development of cracks is an inevitable phenomenon in concrete structural elements, which are subjected to tensile stresses. Cracking can reduce the load bearing capacity of the structure and also accelerate deterioration, thereby shortening the service life and increasing the inspection and maintenance costs. For reinforced concrete (RC), excessive cracking reduces the overall durability by allowing water and other aggressive agents to penetrate, thus accelerating the deterioration, mainly through corrosion, of the reinforcing steel. The corroded reinforcing steel has a reduced cross-sectional area which results in a loss in the bearing capacity of the steel reinforced concrete member, as well as a reduction in the composite action between the constituent materials.

Research studies have shown that under excessive corrosion, reinforcing steel may suffer a significant loss of ductility as well as a reduction in yield and ultimate strength. In addition, there is likely to be a loss of bond strength, which may result in excessive cracking and spalling of the concrete, as well as pull-out failure of the rebars. In this respect, cracking of concrete and reduction in the cross-sectional area of the rebar can endanger the safety and serviceability of RC structures. Chloride–induced corrosion may occur in marine environments where the reinforced concrete structures are exposed to ocean salts, and may also occur inland when deicing salts come in to contact with the concrete surface of pavements and floors of parking garages . The UK’s Department of Transport (DoT) estimates that salt-induced corrosion damage costs around £616.5 million per year on motorway and trunk road bridges in England and Wales alone .

Unsatisfactory durability of concrete structures has not only severe economic impacts, since repairing deteriorated structures can cost almost as much as replacing them entirely, but also industrial, environmental and social challenges due to the reduction of reliability and safety . With this in mind, construction and infrastructure faces a real challenge to improve the resilience, maintenance and rehabilitation of RC structures to minimise the cumulative cost to society. The use of fibre reinforced polymer (FRP) reinforcement, such as carbon (CFRP) and glass (GFRP), can be an effective, sustainable and durable solution to enhance the performance of RC structures in aggressive environments. Another type of FRP that has gained popularity in construction in the recent years is basalt fibre reinforced polymer (BFRP), which is the main subject of interest in the current paper. Basalt FRP does not require the addition of any special additives during production; therefore, it is easier and cheaper to produce than other fibre types such as glass fibre .

The chemical stability of Basalt FRPs is better than glass FRPs, especially under exposure to acids, and they have very good resistance to alkaline exposure as well as corrosion from seawater . There are many economic benefits of using Basalt FRP in construction. The density of basalt is approximately one third of that of steel, which means less cost for transportation and lifting, and other associated construction costs. The tensile strength of Basalt FRP rebars is much higher that the tensile strength of steel reinforcement and consequently, smaller concrete sections can potentially be designed. Furthermore, Basalt FRP rebars do not corrode or absorb water in aggressive environments and therefore the concrete cover distance can be reduced. This is particularly useful in marine and bridge applications which currently require relatively large concrete cover distances, and therefore significant savings in construction and maintenance costs can be achieved. It has been estimated that the energy required for basalt fibre production is around 5 kWh/kg in an electric furnace, whereas the energy required to produce steel is around 14 kWh/kg [8]. It is expected that this saving in energy consumption will have an impact on the environmental performance of BFRP. Basalt FRP reinforcement bars are therefore a promising material in concrete as a replacement for at least some steel and other types of FRP reinforcement.

 

Beyond Materials Group is a growing manufacturer of nonferrous basalt fibre materials and can meet your specification and quality requirements for a wide variety of custom applications. From our head office in Gold Coast we are able to ship our basalt products Australia wide.

Gold Coast, Brisbane, Sydney, Adelaide, Melbourne, Perth.

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