Basalt fiber composite ribs (a high-performance fiber reinforced composite rib material composed of basalt fibers as reinforced material, thermosetting resin (such as epoxy resin) as the matrix, and added with an appropriate amount of additives. The production process combines fiber reinforced, resin composite and molding processes. The following are the detailed production process, key technical points and application characteristics:
1. Core raw materials
Basalt fibers
Source: Continuous fibers made of natural basalt ore (such basalt, etc.) are usually 9-13μm in diameter after high temperature melting (1450-1500℃).
Characteristics: Tensile strength ≥2500MPa, elastic modulus 40-100GPa, high temperature resistance (high temperature above 1000℃), corrosion resistance (acid and alkali, salt spray resistance), strong binding force with resin.
Resin matrix
Commonly used types: epoxy resin (EP), vinyl ester resin (VE), among which epoxy resin has better comprehensive performance (high strength and low curing shrinkage).
Function: Fix the fiber position, transfer load, and protect the fiber from environmental erosion.
Additives
Curing agent: React with resin to cross-link and cure the system (such as amines, acid anhydride curing agents).
Coupling agent: Improves interfacial compatibility between fiber and resin (such as silane coupling agent).
Filler: Increase the stiffness of the ribs or reduce costs (such as quartz sand, calcium carbonate).
2. Production process
The basalt fiber composite ribs mainly adopt the Pultrusion Process, which has the advantages of high production efficiency, high product dimensional accuracy, and stable fiber volume content. The specific steps are as follows:
1. Fiber preparation and arrangement
Fiber bundle: Collect multiple strands of basalt fiber yarns (such as untwisted rovings) into fiber bundles, and control the fiber direction through a guide device (the proportion of axial fibers is ≥60%, ensuring longitudinal strength).
Fiber pre-impregnation: In some processes, the fiber bundle is initially infiltrated through the resin glue tank to remove bubbles and allow the resin to evenly wrap the fibers.
2. Resin impregnation and composite
Resin mixing: Mix resin, curing agent, coupling agent, etc. in proportion, and make a uniform glue solution through a stirring device.
Fiber impregnation: The fiber bundle enters the impregnation tank and is fully impregnated with the resin glue solution. The excess resin is removed through a rubber extrusion device (such as a rubber roller or a metal mold) to control the resin content (usually 30%-40%).
3. Pultrusion and Curing
Mold heating: Preheat the metal mold (usually steel mold) to 80-120℃, and control the temperature in sections (such as low-temperature gel in the first section and high-temperature curing in the latter section).
Traction and molding: The fiber bundle after glue is passed through the mold under the action of a traction machine (such as a crawler traction machine), and the cross-sectional shape of the mold determines the appearance of the rib material (such as a circle, rib shape).
Curing reaction: The resin is cross-linked and cured in the mold to form composite ribs with a certain stiffness. The curing time depends on the mold length, temperature and resin system (usually several minutes to more than ten minutes).
4. Surface treatment and cutting
Surface rib molding: The inner wall of the mold is processed with ring or spiral grooves to form ribs on the surface of the composite ribs, and enhance the bonding force with concrete (rib height 1-2mm, spacing 8-12mm).
Cutting and fixed length: The cured rib material is cut by the cutting machine according to the designed length (such as 6m, 12m), and the finished product is inspected (such as diameter deviation ≤±0.3mm, length error ≤±5mm).
3. Key technical points
Fiber-resin interface bonding
Coupling agent treatment: After the surface of the basalt fiber is treated with silane coupling agent, chemical bond connections can be formed to enhance the interface bond strength (shear strength ≥40MPa) and avoid "fiber pull-out" damage.
Fiber volume content control
Fiber proportion: The volume fraction of fiber is usually 55%-65%. Too high can easily lead to insufficient impregnation of resin, and too low will affect the strength of the ribs. Accurate control by adjusting the number of fiber bundles and mold size.
Curing process optimization
Temperature gradient: The temperature in the front part of the mold is low (such as 80℃) to make the resin gel and the latter part of the mold warm to 120℃ to accelerate the curing, avoiding internal bubbles or cracks due to excessive temperature rise.
Traction speed: usually 0.5-2m/min. If the speed is too fast, it may lead to insufficient curing, and if it is too slow, it will affect production efficiency.
4. Common specifications and performance indicators
Item Typical Parameters Test Standards
Diameters Φ6, Φ8, Φ10, Φ12, Φ16, Φ20, etc. GB/T 32773-2016
Tensile strength ≥600MPa (higher than HRB400 steel bars) GB/T 30022-2013
Elastic modulus 40-55GPa (approximately 1/5-1/4 of steel bars) GB/T 30022-2013
Linear expansion coefficient 8×10⁻⁶/℃ (approximate to concrete to avoid temperature difference cracking) JGJ/T 224-2010
Resistance to salt spray corrosion 1000h Strength retention rate ≥95% GB/T 10125-2021
5. Application advantages and scenarios
Advantages
Corrosion resistance: completely resistant to acid and alkali, salt spray, and chloride ion corrosion, suitable for harsh environments such as oceans and chemicals.
Lightweight and high strength: The density is changed to about 1.9-2.1g/cm³, which is only 1/4 of steel bars. and the tensile strength is more than 2 times that of the steel bar.
Non-magnetic: No electromagnetic induction, suitable for electromagnetically sensitive areas (such as hospitals and tunnels).
Convenient construction: light weight, can be cut manually without mechanical connection.
Typical application scenarios
Concrete structure reinforcement: Replace steel bars for new construction or reinforcement projects (such as bridges, tunnels, building beams and columns).
Marine engineering: Replace steel bars in docks, breakwaters, and cross-sea bridges to solve the problem of steel bar corrosion.
Chemical industry and sewage treatment: pool body and pipeline structure in corrosive environment.
High temperature environment: high temperature resistant parts such as industrial kilns and chimneys (short-term temperature resistance up to 600℃)