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A rebar spacer is a device that secures the reinforcing steel or "rebar" in reinforced concrete structures as the rebar is assembled in place prior to the final concrete pour. The spacers are left in place for the pour to keep the reinforcing in place, and become a permanent part of the structure. The main categories of rebar spacers are: *Linear Spacers (Π-section profiles, H-section profiles, or other 3 dimensional shapes), *Point Spacers (wheel spacers, various tower or chair-like shapes) Rebar spacers can be divided in three raw materials categories: #Concrete spacers #Plastic spacers #Metal spacers The concrete spacers have the advantage of the same raw material which will improve the watertightness and strength of the concrete. Plastic spacers have the advantage of the low cost production and fast processing. == Function == The engineering study of every reinforced concrete construction, whether it is a building, a bridge, a bearing wall or other structure, predicts the positioning of steel rebars at specific positions in the volume of concrete (predicted concrete cover of steel reinforcement bars). This cover typically varies between 10 and 100 mm. The statics of every concrete construction are designed in such a way that steel and concrete properties are combined in order to achieve the maximum possible strength for the particular construction (e.g. anti-earthquake protection) as well as to prevent the long-term corrosion of steel that would weaken the construction. Rebar spacers secure the correct position of steel, thus assisting in the practical application of the theoretical specifications of concrete construction. The cover of the steel of a particular construction element (for example in a concrete slab or a beam) should be generally uniform within the element. Most of the time the cover height is half of the total thickness of the element being built, for example if your wall ist 10 cm thick then your rebar should be set right in the middle of it at 5 cm (which is also the cover height requiered). The use of spacers is particularly important in areas with high earthquake activity in combination with corrosive environment (like proximity to salt water of sea), as for example Japan, Iran, Greece, California etc. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Rebar spacer」の詳細全文を読む スポンサード リンク
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