CORROSION PROBLEM IN CONCRETE
Corrosion in rebar is the most common cause of failure in buildings, bridges, tunnels & structures. RUST-X CCI’s are effective in increasing the service life of the concrete structures by reducing the corrosion rate of rebar in the concrete.In case of the concrete structures, the sand, the salts present in the sand as well as the water in the concrete entering due to porosity play an important role in causing corrosion of the rebar.The rebar forms small electrochemical cells all over the surface due to presence of water and salts which work as electrolyte and cause corrosion.The corrosion rate is higher in aggressive environments in the coastal areas as well as for constructions under water or underground such as bridges or tunnel and lead to cracking and failing of structures.
The CCI’s play an important role in drastically reducing the corrosion rate and extending the service life of the constructed bridges, buildings, roadways as well as tunnels.
CCI Migration Process & Protection Mechanism
Step 1: Migrating CCI is spray applied on concrete with rebar
Step 2: Migrating CCI penetrated inwards into the concrete and formed iconic bond with rebar
CCI 4207 Migratory Corrosion Inhibiting Powder for Concrete Admixtures Roads – Bridges – Flyovers
Roads, bridges & flyovers are the basic necessities for the growth and development of any nation. A very high amount of investment and manpower goes in the establishment of such infrastructure. The rate of corrosion is one of the major factor that determines the life of the infrastructure. As the corrosion grows on rebar the bond between the concrete and the rebar is reduced. so do the cracks in the concrete which results in wearing off of the roads.
The corrosion rate of rebar is different in different environmental conditions. Coastal areas, hot and humid areas as well as areas under constant rainfall and snow may have higher corrosion rates. As a vehicle passes over the wet road, the tyres push the water droplets into the concrete. In case of chlorides present on the road due to coastal rain or from the snow melting pellets, these chloride molecules also penetrate as well as get pushed inside the concrete of the road.
The corrosion rate of the rebar increases due to presence of water and salts. RUST-X CCI 4207 powder is an excellent corrosion inhibitor which can be mixed with the concrete during the construction. The inhibitor is a mixed inhibitor with multimodal action of contact, in-situ as well as migratory corrosion inhibitor where the inhibitor has the power to evaporate and reach metal due to its affinity towards metal surface.
Current Measurement Using Half Cell Potential system for concrete
CCI 4204 Migratory Corrosion Inhibiting Liquid for Concrete Structures
Many bridges, buildings and road networks have not been treated with corrosion inhibiting chemicals at the time of construction. The exposure to water and chlorides exposes the concrete to corrosion and deteriroration of the rebar. As the corrosion occurs, the oxides of iron occupy greater space compared to the rebar and cause stresses within the concrete. It also loosens the concrete rebar bond and causes cracking of the concrete around the rebar. This deterioration may be happening at a much higher rate for the un-inhibited structures where the corrosion inhibiting additives have not been incorporated into the admixtures.
This could be occuring in under use buildings, bridges and roads etc. RUST-X CCI 4204 is a liquid applied corrosion inhibitor which gets adsorbed into the concrete and migrates towards the rebar. The application of the CCI 4204 immediately results in the reduction of the electron flow rate and hence corrosion of the rebar within the concrete.
The effect can be verified by measuring the half cell potential of the concrete and measuring the electron flow. The CCI 4204 can be sprayed on the existing structures and due to capillary absorption action it flows inwards into the concrete. The liquid has a high affinity towards the iron rebar and forms a coat over the rebar which stays for a long period and provides excellent protection to the rebar.
CCI 4206 Concrete Admixture Additive
for Buildings
Concrete can cause corrosion to rebar due to water during construction as well as its natural hygroscopicity and water retention.The CCI 4206 can be mixed at 1% with concrete to provide excellent corrosion inhibitory effect. The presence of the CCI 4206 molecules within the concrete make it highly corrosion inhibiting reducing the oxidation rate by 80-90% and hence increasing the life of the building from 5 – 10 times. The crack propagation in concrete is drastically reduced.
The effect of corrosion inhibition is highly beneficial in coastal areas, rainy places where buildings remain damp all the time as well as in places having high humidity or having high salt content in soil and sand.
The dosage recommended is 10 kg per m3 of the admixture for normal environments and 20 kg/m3 for aggressive environments.The addition of the CCI 4206 does not have any detrimental effect on the setting time or compressive strength of the cement.
Figure 1 shows the metal weight loss or corrosion loss of steel rebar in salt water during an immersion test in salt water
Figure 2 shows the corrosion rate of steel rebar in salt water.