What is the difference between fiberglass rebar and rebar?
Glass fiber reinforced plastic: a composite material made of high-strength glass fiber as a reinforcing material, synthetic resin as a matrix material, and mixed with appropriate amount of auxiliary agents, called glass fiber reinforced plastic (English abbreviation: FRP), commonly known as glass fiber reinforced plastic. There are mainly "glass fiber rebar" and "basalt fiber rebar". (Φ6mm～Φ36mm)
Reinforcing bar (also known as ribbed steel) is a kind of steel bar and a kind of building material. For example in reinforced concrete, the skeleton used to support the structure. Including smooth round bars, ribbed bars, torsion bars. There are many types of rebar, usually classified by chemical composition, production process, rolled shape, supply form, diameter size, and use in the structure. Reinforcing bars are mainly subjected to tensile stress in concrete. Due to the action of ribs, deformed steel bars have greater bonding ability with concrete, so they can better withstand the action of external forces. Steel bars are widely used in various building structures, especially large, heavy, light thin-walled and high-rise building structures.
Glass fiber: also known as alkali-resistant glass fiber, alkali-resistant glass fiber is a rib material of glass fiber reinforced (cement) concrete (referred to as GRC), an inorganic fiber, and an ideal substitute for steel and asbestos in non-load-bearing cement components . The characteristics of alkali-resistant glass fiber are good alkali resistance, can effectively resist the erosion of high alkali substances in cement, strong gripping force, high elastic modulus, impact resistance, tensile and bending strength, non-flammable, frost-resistant, temperature-resistant , strong humidity change ability, excellent crack resistance, impermeability, strong designability, easy molding and other characteristics, alkali-resistant glass fiber is a new type of green and environmentally friendly reinforcement widely used in high-performance reinforced (cement) concrete Material.
Scope of application of glass fiber reinforcement:
1. It can be widely used in highways, bridges, airports, docks, stations, water conservancy projects, underground engineering and other fields;
2. Suitable for use in corrosive environments such as sewage treatment plants, chemical plants, electrolytic cells, manhole covers, and coastal defense projects;
3. Suitable for use in military engineering, security engineering, special engineering and other environments requiring insulation and demagnetization;
The characteristics of glass fiber reinforcement:
1. High tensile strength: the tensile strength is better than that of ordinary steel, 20% higher than that of steel bars of the same specification, and has good fatigue resistance; 2. Light weight: only 1/4 of the same volume of steel bars, with a density of 1.5-1.9 (g/cm3): 3. Strong corrosion resistance: corrosion resistance of chemicals such as acid and alkali can resist the corrosion of chloride ions and low PH value solutions, especially the corrosion resistance of carbon compounds and chlorine compounds is stronger; 4 1. Strong material bonding force: the thermal expansion coefficient is closer to cement than steel, so the bonding force between FRP reinforcement and concrete is stronger; 5. Strong designability: the elastic modulus is stable. Stable dimensions under thermal stress, bending and other shapes can be arbitrarily thermoformed; good safety performance, non-thermal, non-conductive, flame-retardant and anti-static, no sparks will be generated by collision with metal through formula changes; 6. Strong magnetic wave permeability: FRP ribs The material is a non-magnetic material, and does not need to be demagnetized in non-magnetic or electromagnetic concrete components; 7. Convenient construction: standard and non-standard parts of various sections and lengths can be produced according to user requirements, and can be used for on-site binding Non-metal tensioning belt, easy to operate.
Rebar production requirements:
When the steel bar is processed and produced, the steel bar processing table and the design drawing should be reviewed, and the blanking table should be checked for errors and omissions. The actual samples are released from the table, and the batches can be produced only after the trial production is qualified. The processed steel bars should be listed and stacked in an orderly manner.
If replacement of steel bars is required during construction, it is necessary to fully understand the design intent and the properties of the replacement materials, strictly abide by the various provisions of the current reinforced concrete design specifications, and do not replace low-strength steel bars with high-strength steel bars of the same area. The replacement of steel bars in important parts shall be subject to the consent of Party A and the design unit, and can be replaced only when there is a written notice.
(1) The surface of the steel bar should be clean, and the sticking oil, soil and rust must be cleaned before use, and the rust can be removed by combining with the cold drawing process.
(2) The steel bar can be straightened mechanically or manually. The straightened steel bars shall not have local bending, dead bends or small waves, and the surface scars shall not reduce the cross-section of the steel bars by 5%.
(3) The steel bar should be cut according to the number, diameter, length and quantity of the steel bar, and the length should be matched. The long material should be cut first and then the short material should be cut, and the short end of the steel bar should be minimized and shortened to save steel.
(4) Rebar hook or bend:
①Rebar hook. There are three forms, namely semi-circular hook, straight hook and oblique hook. After the steel bar is bent, the inner skin shrinks at the bend, the outer skin extends, and the length of the axis remains unchanged, and a circular arc is formed at the bend. The size after bending is not larger than the blanking size, and the bending adjustment value should be considered.
The diameter of the bending center of the steel bar is 2.5d, and the straight part is 3d. The theoretical calculation value of the increased length of the steel bar hook: 6.25d for the half-circle hook, 3.5d for the straight hook, and 4.9d for the oblique hook.
②Bend the steel bar. The bending diameter D of the bending part of the middle part is not less than 5 times the diameter of the steel bar.
③ Stirrups. The ends of the stirrups should be hooked, and the hook form should meet the design requirements. Stirrup adjustment, that is, the difference or sum of the added length of the hook and the bending adjustment value, depends on the outer size or inner size of the stirrup.
④The length of the steel bar cutting should be comprehensively considered according to the size of the component, the thickness of the concrete protective layer, the adjustment value of the steel bar bending and the length of the hook.
a. Straight steel bar cutting length = member length - protective layer thickness + hook increase length,
b. Bending steel bar cutting length = straight section length + oblique bending length - bending adjustment value + hook increase length,
c. Stirrup cutting length = stirrup inner perimeter + stirrup adjustment value + hook increase length.
Rebar processing generally goes through four processes: rebar rust removal; rebar straightening; rebar cutting; rebar forming.
When the steel bar joint is connected by straight thread or conical thread, the upsetting and thread processing process of the steel bar end should be added. Rebar batching and substitution.
Replacement of steel bars
(1) When replacing the steel bars specified in the design documents with steel bars of another steel grade or diameter, the following provisions shall be observed:
It should be carried out according to the principle that the design value of the steel bearing capacity is equal. After the replacement of the steel bar, the specified structural requirements such as the spacing of the steel bars, the length of the anchoring, and the diameter of the steel bars should be met.
When replacing lower-grade steel bars with higher-grade steel bars, it is advisable to use the method of changing the diameter of the steel bars rather than the method of changing the number of steel bars to reduce the cross-sectional area of the steel bars.
(2) When replacing a steel bar of a certain diameter with the same steel grade, the diameter variation range should not exceed 4mm, and the ratio of the total cross-sectional area of the steel bar after the change to the cross-sectional area specified in the design document should not be less than 98% or greater than 103% .
(3) When the design main reinforcement is replaced with the same steel grade, the spacing should be kept unchanged, and two types of reinforcement with a diameter larger and smaller than the design steel diameter can be used for substitution.