The specifications for steel bar shall be set out in the import and export trade contract. They should generally include the standard grade (type code), nominal diameter of the rebar, nominal weight (mass), specified length and tolerance values of the above indicators.
Our standards recommend a range of rebar with nominal diameters of 6, 8, 10, 12, 16, 20, 25, 32, 40 and 50 mm. The length of supply is divided into two types: fixed length and multi-length. China’s export rebar is 6 to 12m in fixed length, and Japanese rebar is 3.5 to 10m in fixed length; domestic rebar is usually 9m and 12m in fixed length if not specified in the contract.
(1) Surface quality. The relevant standards stipulate the surface quality of the rebar, requiring the ends to be cut straight and the surface to be free from cracks, scars and folds, and to be free from defects harmful to use.
(2) Allowable deviations in external dimensions. The bending of the rebar and the geometry of the rebar are specified in the relevant standards.
GB1499.2-2007 (Steel for reinforced concrete Part 2: Hot-rolled ribbed reinforcing bars)
GB1499.2-2007/XG1-2009 “Steel for reinforced concrete Part 2: Hot-rolled ribbed steel bars” National Standard No. 1 Revision; GB/T 2101-2008 (General provisions for acceptance, packaging, marking and quality certification of steel sections)
GB1499.1 to GB1499.3 (Reinforcing steel for concrete); JIS G3112-87 (98) (Bar steel for reinforced concrete); JISG3191-66 (94) (Shapes, dimensions, weights and their tolerances for hot-rolled and rolled bar steel); BS4449 -97 (Hot-rolled steel bars for concrete structures).
(1) Test methods: The following standard test methods are commonly used for testing and analysing the above chemical composition: GB/T223, JISG1211?1215, BS1837, BS Manual 19, etc.
(2) Component indicators: The main indicators for assessing the content of rebar components are: C, Mn, P, S, Si, etc., with different grades and different contents.
There are differences between the grades and the content, the general range is: C (0.10-0.40%), Mn<1.80%, P<0.050 %, S<0.050%, Si (0.60-1.00%).
Rebar is widely used in the construction of houses, bridges, roads and other civil engineering projects. From highways, railways, bridges, culverts, tunnels, flood control, dams and other public facilities to the foundations, beams, columns, walls and slabs of buildings, rebar is an indispensable structural material. With the increasing urbanisation in China, there is a strong demand for rebar in the booming development of infrastructure construction and real estate.
When buying rebar, the first thing to do is to look at the external dimensions, using a vernier card gauge to simply measure whether the actual size is smaller than the stated size (generally the rebar is rolled with a specification mark) by about one specification or more (e.g. the standard internal diameter of a 12 rebar is 11.5±0.4mm
Secondly, the surface quality is poor due to the use of adobe, often with defects such as scars and an overall roughness. At the same time, some small rolling mills have a reddish surface colour due to insufficient heating temperature and rolling speed.
Third, most of the regular steel in the factory when the factory large bundles of packaging, bundles of steel are hung with the actual corresponding metal tags, indicating the manufacturer, steel grade, batch number, specifications and inspection code, etc..
When buying rebar, users are advised to go to a regular steel business unit or point of sale, obtain a certificate of steel quality and carry out an inspection. Those with quality doubts can go to a professional inspection agency for quality advice and testing.