| 摘要 |
<p>19 Concrete strengthening members, particularly prestressing tendons such as strands of steel wire, are provided with a strongly adherent plastic coating which may be substantially impermeable for improved corrosion resistance, and/or which may have embedded therein abrasive or grit-form particles to provide improved bond with the concrete, and particularly to provide controllable bond transfer in prestressing tendons of the pretensioned type. The plastic coating preferably is applied electrostatically in powder form, and fusion bonded by heat. The abrasive can be applied by spraying during a viscous state of the heated resin, and can be varied as to size and spacing density so as to control the surface condition and the bonding effect. Fusion and curing heat may come from preheating of the member before application of the resin powder, which preferably is a heat curable, thermosetting epoxy. Coating thickness and grit application are readily variable to meet particular requirements. Particularly advantageous results are achievable for high strength steel strands for prestressing concrete by pretensioning, facilitating their use where previously considered impractical or impossible.</p> |
