Decrease in The Quality of Concrete and Reinforcing Steel


Decrease in The Quality of Concrete and Reinforcing Steel

The decrease in the performance of the existing material or structure can be caused by weathering of the structural material. Weathering of structural materials can occur due to age, environmental factors, chemical attack, fire, earthquake, or flood.


Main Problem

1. Carbonation

Carbon dioxide and other gasses in the air penetrate (penetrate) into the concrete through the pores of the concrete. If there is water2(H2O), carbon dioxide (CO2and other acid gasses can react with calcium hydroxide in concrete and form a neutral compound calcium carbonate (CaCO3This process is called carbonation. The changes that occurred caused the pH of the concrete to drop from ± 12.5 to ± 8.5 and in the end caused cracks in the outer layer which was restrained by the non carbonated concrete. 

Carbonation can also change the physical characteristics of concrete, such as the occurrence of degradation in the test value of concrete surface hardness (concrete homogeneity) and concrete quality, and affect the durability or durability of concrete. In addition, the carbonation can also cause the reinforcing steel to be unprotected and corrode.

2. Corrosion of Reinforcing Steel

Initially, corrosion occurs because the concrete surface has been exposed to carbonation or the presence of chloride ions, moisture, and oxygen. This corrosion will result in an increase in stress in the reinforcing steel until cracks occur. In general, cracks will develop from the reinforcement to the concrete surface. In addition, corrosion also causes a reduction in the area of reinforcing steel which will result in reduced structural capacity.



  • Carry out corrosion cleaning on reinforcing steel by using a rust remover. Then, an anti-rust coating is carried out using a rush converter.
  • Replace the reinforcement that is severely damaged by cutting the existing reinforcing steel and replacing it with new reinforcement by splicing the reinforcement using the welding method.
  • Increasing the thickness of the concrete blanket, increasing the density of the concrete, and repairing damage to the concrete surface because this will be a way for air to enter the concrete. Several methods of repairing concrete surfaces (repair concrete) carried out include:
      • Injection (Injection)for crack repair by injection of epoxy resin material.
      • Patching (patching)for repairing small-scale chipped surfaces by hand.
      • Groutingfor repairing lumpy surfaces on a large scale using a pump.
      • Protection and reinforcement with FRP (CFRP/GFRP) with Tyfo S for dry structure areas and Tyfo SW for wet or flooded areas.
      • Coating, protection of concrete from the environment by coating liquid coating.



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