The corrosion resistance mechanism of the hot-dip galvanized W beam layer of the corrugated guardrail board, and the hot-dip galvanized layer of the base material of the corrugated guardrail board have three major functions

The corrosion resistance mechanism of the hot-dip galvanized W beam layer of the 

corrugated guardrail board, and the hot-dip galvanized layer of the base material 

of the corrugated guardrail board have three major functions.

(1) Isolation and protection.

Although zinc is highly reactive to metals, corrosion develops slowly in the atmosphere

and in near-neutral water. This situation is due to the formation of insoluble zinc 

and cadmium corrosion products on the surface of the zinc. 

Zn(OH): The dense ZnO film is equivalent to forming apassivation protective film on the surface of zinc, that is, the passivation of zinc, and its protection mechanism is isolation protection.

(2) Cathodic protection.

The zinc film (dissolving film) is not easy to form a passivation film in an acid-base 

environment, and accelerates the corrosion of zinc, causing it to lose its important 

role of self-protection. Fovarious reasons, the zinc layer cannot be completely purified 

or homogeneous, and there is always a certain amount of impurities, regions with 

inhomogeneous electrochemical properties. In the solution, countless particles are 

formed in different media and cannot pass through the different anode and cathode 

regions, forming a battery that is locally electrochemically corroded.

Since zinc is more active than iron, it is the anode of micro-battery. 

It is a sacrificial anode,protectedby the current generated by the continuous dissolution. The research 

results show that metal materials themselves will be corroded after being anodized; 

iron is the cathode of micro-batteries, which can only be used forelectrical  

conductivity and electronic functions, and is protected by environmental protection. 

During hot-dip galvanizing, the zinc-iron alloy layer is indirect contact with the 

substrate. However, the potential of the alloy layer is smaller than the iron potential, 

and the substrate will not be protected. Zinc is used as an anode for steel in almost 

all electrolytes. This technological performance of the galvanized coating makes 

it possible to protect the galvanized coating even if it is damaged or slightly 

discontinuous.

(3) In addition, during the selective dissolution process of the coating, due to the 

formation of corrosion products, the volume of the galvanized layer increases and 

the gap healing is poor, which affects the further development of electrochemistry. 

This is evident in the corrosion development of the hot-dip coating.

FORST highway guardrail beam adopts AASHTOM111 hot-dip galvanizing standard, 

and there are two types of 550g/㎡ and 1100g/㎡ according to the thickness of the 

guardrail beam. It can be used for 20-30 years under normal circumstances.