There are many factors that affect the bonding and anchoring performance of epoxy resin coated steel bars.
1. The effect of coating thickness: when the diameter of the steel bar is different, the larger the steel bar diameter and the thicker the coating, the greater the reduction in bonding strength.
2. The influence of the shape of the steel bar: the bonding and anchoring performance of the coated steel bar changes with the change of the angle between the rib and the axis of the steel bar and the steepness of the thread.
3. The influence of the thickness of the concrete protective layer: the increase in the thickness of the protective layer also increases the bonding and anchoring performance.
4. The effect of the bending shape of epoxy resin coated steel bars: the hooked or bent ones are better than straight steel bars.
5. The strength of concrete and the restraint effect of stirrups: as the strength of concrete increases, its bonding and anchoring performance improves, and the bonding strength of epoxy resin-coated steel bars is proportional to the square root of the concrete strength; in addition, epoxy resin with stirrups The bonding strength of coated steel bars is significantly improved compared with that without stirrup constraints.
The bonding and anchoring strength of epoxy resin-coated steel bars is about 10% lower than that of uncoated steel bars under normal conditions, and no more than 20% under the most unfavorable conditions. Therefore, in order to ensure the bonding and anchoring strength between the coated steel bars and concrete, it is necessary to increase the anchoring length of the coated steel bars by a certain value, and increasing the anchoring length will inevitably increase the cost of raw materials. In general, the reserved anchoring length is 25% higher than the anchoring length of ordinary steel bars.
The increased construction and labor costs of epoxy-coated steel bars account for about 25% of the total project cost. The one-time investment is very large, but epoxy-coated steel bars can effectively prevent corrosion of steel bars and effectively reduce the use period The maintenance and management cost of the structure is increased, and the service life of the structure is extended by more than 20 years. Therefore, from the cost-benefit analysis, it still has very good economic and social benefits. Especially for structures in a corrosive environment, epoxy resin coating is applied. The economic and social benefits of steel reinforcement technology are even greater.