【Daily Question】Utilities - Civil Engineering - 20190420

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(　　) is produced by tensioning grade II-III heat-treated steel bars at room temperature followed by aging treatment. It can be used directly as prestressed reinforcement. 　　A. Cold-drawn low-carbon steel wire B. Cold-drawn rebar C. Carbon steel wire D. Heat-treated rebar 【Answer】B 【Explanation】Types of prestressed rebar 1. Cold-drawn low-carbon steel wire 2. Cold-drawn rebar: This is obtained by stretching rebar of grades II–III at room temperature and then subjecting it to aging treatment. It can be used directly as prestressed reinforcement. 　　3. Carbon steel wire (stress-relief wire) Carbon steel wire is made from high-carbon steel bars through quenching, pickling, and drawing. 　　4. Steel strands are generally formed by twisting 6 carbon steel wires around a central wire in a spiral shape, followed by low-temperature tempering. 　　5. Heat-treated steel bars: Heat-treated steel bars are produced by subjecting ordinary hot-rolled medium-carbon alloy steel to quenching and tempering heat treatment.