阅读说明：本技术 一种螺旋形玄武岩微筋及制备方法 (Spiral basalt micro-bar and preparation method thereof ) 是由 丁一宁 王庆轩 葛茂林 李东升 晏楚 陈佳军 于 2021-08-02 设计创作，主要内容包括：本发明提供一种螺旋形玄武岩微筋及制备方法,属于新型复合材料领域。该微筋包括玄武岩单丝纤维和耐碱浸润剂；将500～1500根平行的玄武岩单丝纤维通过耐碱浸润剂集束粘结后,依次经挤压成形、螺旋扭转、二次浸润、烘干硬化、切断后得到螺旋形玄武岩微筋。该微筋的制作工艺简单,截面刚度高,掺入混凝土中不易结团与脆断,可显著提高微筋在新拌混凝土中的掺量上限；微筋的螺旋形结构可改善其与混凝土之间的粘结性能,能够更加有效地桥接裂缝和限制裂缝扩展,从而显著改善混凝土的力学性能与耐久性；此外,微筋具有良好的耐碱、耐氯盐腐蚀性能,有利于提高混凝土的耐久性。(The invention provides a spiral basalt micro-bar and a preparation method thereof, belonging to the field of novel composite materials. The micro-ribs comprise basalt monofilament fibers and an alkali-resistant impregnating compound; 500-1500 parallel basalt monofilament fibers are bundled and bonded by an alkali-resistant impregnating compound, and then sequentially subjected to extrusion forming, spiral twisting, secondary impregnation, drying hardening and cutting to obtain the spiral basalt micro-bar. The micro-bar has simple manufacturing process and high section rigidity, is not easy to agglomerate and brittle fracture when being doped into concrete, and can obviously improve the upper limit of the doping amount of the micro-bar in the fresh concrete; the spiral structure of the micro-ribs can improve the bonding property between the micro-ribs and concrete, and can bridge cracks and limit crack expansion more effectively, so that the mechanical property and durability of the concrete are improved remarkably; in addition, the micro-ribs have good alkali resistance and chloride salt corrosion resistance, and are beneficial to improving the durability of concrete.)

1. The spiral basalt micro-bar is characterized by comprising monofilament fibers (1) and an alkali-resistant impregnating compound (5); bundling and bonding 500-1500 parallel monofilament fibers (1) by an alkali-resistant impregnating compound (5), and then sequentially carrying out extrusion forming, spiral twisting, secondary impregnation, drying hardening and cutting to obtain the spiral basalt micro-bar, wherein the section of the spiral basalt micro-bar is rectangular, the length of the spiral basalt micro-bar is 30-60 mm, and the pitch of the spiral basalt micro-bar is 15-25 mm.

2. The spiraling basalt micro-bar according to claim 1, characterized in that the monofilament fiber (1) is basalt monofilament fiber.

3. The spiral basalt micro-bar according to claim 1, wherein the rectangular shape has an aspect ratio of 2 to 5 and an equivalent diameter of 0.5 to 0.8 mm.

4. The spiral basalt micro-bar of claim 1, wherein the surface form of the micro-bar is a spiral structure.

5. The spiral basalt micro-bar as claimed in claim 1, wherein the alkali-resistant wetting agent (5) is modified alkali-resistant epoxy resin, modified polyacrylate, modified polyvinyl acetate.

6. The method for preparing the spiral basalt micro-bar as recited in any one of claims 1 to 5, characterized by the following steps:

firstly, bundling and bonding 500-1500 parallel monofilament fibers (1) through an alkali-resistant impregnating compound (5), and then extruding a fiber bundle into a rectangle by adopting a special mold;

secondly, before the alkali-resistant impregnating compound (5) is hardened, twisting the fiber bundle along the length direction to prepare a spiral fiber bundle, and controlling the thread pitch to be 15-25 mm;

thirdly, performing secondary infiltration on the prepared spiral fiber bundle in an alkali-resistant impregnating compound (5);

and fourthly, drying and hardening the secondarily soaked spiral fiber bundle, and then cutting the spiral fiber bundle into a short fiber bundle with the length of 30-60 mm, namely the spiral basalt micro-bar.

7. The method for preparing the spiral basalt micro-bar according to claim 6, wherein the soaking time of the third step is 5-30 s.

8. The preparation method of the spiral basalt micro-bar according to claim 6, wherein the drying and hardening temperature is 150-200 ℃, and the drying time is 2-5 min.

Technical Field

The invention relates to a spiral basalt micro-bar and a preparation method thereof, belonging to the field of novel composite materials.

Background

The basalt fiber has high tensile strength (>3000MPa), good corrosion resistance, good thermal stability and the like. Compared with glass fiber, the basalt fiber is more green and environment-friendly; the total energy consumption (13MJ) required by producing basalt fiber per kilogram is reduced by 46 percent compared with glass fiber (24MJ), and the alkali resistance of the basalt fiber is higher and is equal to alkali resistance glass fiber (14.5wt percent ZrO)₂) Rather, it is more suitable for application in the strongly alkaline environment (pH) of concrete matrix>12.5). Compared with steel fibers, the basalt fibers have more excellent chloride ion corrosion resistance, and when the basalt fibers are used as a reinforcing material in concrete, the basalt fibers can avoid the corrosion problem similar to the steel fibers, and the basalt fibers are ensured to have good corrosion resistance at concrete cracks, so that the durability and the applicability of the concrete are improved. At present, the chopped basalt fibers mainly comprise the following three types: monofilament fiber, flat micro-ribs and ribbed micro-ribs; wherein, the straight micro-ribs and the ribbed micro-ribs are not put into engineering application yet. The three types of chopped basalt fibers have the following problems when applied to concrete:

1) the monofilament fiber is a main product applied to engineering at present, the diameter of the monofilament fiber is generally less than 20 microns, the negative influence of the small section rigidity and the extremely high fiber number per unit mass (table 1) on the working degree of fresh concrete is great, the agglomeration phenomenon of the fiber in the concrete (figure 1a) and the obvious increase of the air content of the concrete are easily caused, and the fiber mixing amount is difficult to increase. Therefore, the monofilament fiber has little toughening effect on concrete, and mainly limits shrinkage cracks in the concrete at a low dosage.

TABLE 1 physical and geometric characteristic parameters of basalt monofilament fiber and spiral basalt micro-bar

2) Before the flat micro-ribs and the concrete are debonded, the bonding performance of the flat micro-ribs and the concrete is mainly determined by the chemical and physical bonding force of the micro-ribs and the concrete; after the debonding, the flat micro-ribs slide in the concrete, the pulling load is quickly reduced, and the bonding performance mainly depends on the friction force. The area surrounded by the bonding-sliding curve of the straight micro-ribs is smaller (figure 2), the sliding energy consumption capability of the micro-ribs is weaker, and the toughening effect on concrete is poorer.

3) The manufacturing process of the ribbed micro-ribs is complex; in addition, the transverse ribs may be stripped from the chopped fiber bundle core column in the stress process, so that the toughening effect of the ribbed micro-ribs on the concrete is reduced.

Disclosure of Invention

Aiming at the defects of the application of the chopped basalt fiber in concrete, the invention aims to provide a basalt micro-bar with a spiral structure, as shown in figure 4. Compared with monofilament fiber, the section rigidity of the micro-rib is improved by nearly 8.76 multiplied by 10⁵The concrete admixture is multiplied (table 1), and is not easy to agglomerate and brittle fracture when being mixed into concrete, so that the upper limit of the mixing amount of the micro-bars in the concrete can be obviously improved; compared with the flat micro-bar, the micro-bar has better bonding performance with concrete, as shown in figure 2. Therefore, the micro-ribs can obviously improve the mechanical property and the durability of the concrete. In addition, compared with the ribbed micro-rib, the manufacturing process of the micro-rib is simpler and the cost is lower.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the spiral basalt micro-rib has a cross section shown in figure 3 and comprises monofilament fibers 1 and an alkali-resistant impregnating compound 5. The monofilament fiber 1 is basalt monofilament fiber; the alkali-resistant impregnating compound 5 is modified alkali-resistant epoxy resin, modified polyacrylate, modified polyvinyl acetate and the like. Bundling and bonding 500-1500 parallel monofilament fibers 1 by using an alkali-resistant impregnating compound 5, and then sequentially carrying out extrusion forming, spiral twisting, secondary impregnation, drying hardening and cutting to obtain spiral basalt micro-bars, wherein the cross section of each spiral basalt micro-bar is rectangular, the length of each spiral basalt micro-bar is 30-60 mm, and the thread pitch of each spiral basalt micro-bar is 15-25 mm; the length-width ratio of the rectangle is 2-5, and the equivalent diameter is 0.5-0.8 mm.

A preparation method of spiral basalt micro-bars comprises the following steps:

firstly, 500-1500 parallel monofilament fibers 1 are bundled and bonded through an alkali-resistant impregnating compound 5, and then a special die is adopted to extrude the fiber bundle into a rectangle.

And secondly, before the alkali-resistant impregnating compound 5 is hardened, twisting the fiber bundle obtained in the first step along the length direction to obtain a spiral fiber bundle, wherein the pitch is controlled to be 15-25 mm.

And thirdly, carrying out secondary infiltration on the prepared spiral fiber bundle in an alkali-resistant impregnating compound 5 for 5-30 s.

And fourthly, drying and hardening the secondarily soaked spiral fiber bundle at the temperature of 150-200 ℃ for 2-5min, and cutting the spiral fiber bundle into short fiber bundles with the length of 30-60 mm, namely the spiral basalt micro-bar.

The invention has the advantages that:

1) compared with monofilament fiber, the spiral micro-ribs have larger section rigidity (table 1), are distributed in a concrete matrix more uniformly (figure 1b), can avoid the phenomena of caking and brittle failure of the spiral micro-ribs in concrete, and obviously improve the upper limit of the micro-rib mixing amount allowed by the working degree of fresh concrete.

2) Before the spiral micro-ribs and the concrete are debonded, the bonding performance of the spiral micro-ribs and the concrete is mainly determined by the chemical and physical bonding force of the micro-ribs and the concrete; after the debonding, the bonding performance mainly depends on the diagonal extrusion force γ (see fig. 2) distributed along the length direction of the micro-bar due to the spiral structure, in addition to the friction force τ of the micro-bar and the concrete. Along with the increase of the slippage, the spiral micro-rib begins to deform, and the change amplitude of the extraction load is smaller. Compared with the straight micro-rib, the spiral micro-rib has a fuller bonding-sliding curve in concrete, a larger surrounding area and more excellent sliding energy consumption capability, and can bridge and limit crack expansion more effectively, so that the mechanical property (such as toughness) and durability of the concrete are obviously improved.

3) Compared with the ribbed micro-ribs, the spiral micro-ribs are simpler and more economical in manufacturing process. In addition, the spiral micro-ribs can also avoid possible peeling between the transverse ribs of the ribbed micro-ribs and the chopped fiber bundle core column.

4) Compared with the micro-ribs with the circular cross section, the micro-ribs with the rectangular cross section are easier to twist along the length direction of the micro-ribs to obtain a spiral structure; when the cross-sectional area and the length are the same, the micro-bars with the rectangular cross section have larger contact area with the concrete, and the bonding performance of the micro-bars and the concrete is improved.

Drawings

FIG. 1 shows the distribution of the fibers in fresh concrete: (a) basalt monofilament fiber; (b) spiral basalt micro-ribs;

FIG. 2 is a force diagram and a bonding-slipping curve of straight basalt micro-bars and spiral basalt micro-bars in concrete;

FIG. 3 is a cross section of a spiral basalt micro-tendon;

FIG. 4 shows the appearance and geometry of spiral basalt micro-tendon, where p_fThe pitch of the micro-ribs (15-25 mm) is l_fThe length of the micro-ribs is 30-60 mm, and the micro-ribs have rectangular cross sections (a, b, d)_eThe width, the length and the equivalent diameter of the rectangle are respectively, the length-width ratio is 2-5, and the equivalent diameter is 0.5-0.8 mm);

FIG. 5 is a load-deflection curve of different fiber concrete samples.

In the figure: 1 basalt monofilament fiber, 2 spiral basalt micro-rib, 3 coarse aggregate, 4 concrete matrix and 5 alkali-resistant impregnating compound.

Detailed Description

The invention is further described with reference to the following drawings and specific embodiments.

The spiral basalt micro-rib has a cross section shown in figure 3 and comprises monofilament fibers 1 and an alkali-resistant impregnating compound 5. The monofilament fiber 1 is basalt monofilament fiber; the alkali-resistant impregnating compound 5 is modified alkali-resistant epoxy resin. 500-1500 parallel monofilament fibers 1 are bundled and bonded by an alkali-resistant impregnating compound 5, and are subjected to extrusion forming, spiral twisting, drying and hardening and cutting to obtain the spiral basalt micro-bar, the cross section of the spiral basalt micro-bar is rectangular (the length-width ratio is 2, and the equivalent diameter is 0.55mm), the length of the spiral basalt micro-bar is 35mm, the thread pitch of the spiral basalt micro-bar is 20mm, and the appearance form of the micro-bar is shown in figure 4.

Fig. 1 compares the distribution state of basalt monofilament fiber and spiral basalt micro-bar in the fresh concrete, and it can be seen from the figure that the basalt monofilament fiber is agglomerated in the concrete, while the spiral basalt micro-bar is distributed more uniformly in the concrete matrix, so that the agglomeration phenomenon of the micro-bar in the concrete is avoided.

FIG. 2 is a graph comparing the bonding-slippage curves of straight basalt micro-tendon and spiral basalt micro-tendon in concrete, and it can be seen from the graph that the bonding performance of the spiral basalt micro-tendon and the concrete after debonding mainly depends on the oblique extrusion force gamma distributed along the length direction of the micro-tendon caused by the spiral structure, except the friction force tau; compared with the straight basalt micro-rib, the spiral basalt micro-rib has a fuller bonding-sliding curve in concrete, a larger surrounding area and more excellent sliding energy consumption capability.

FIG. 5 compares the load-deflection curves of different fiber reinforced concrete test pieces under the four-point bending test condition. Basalt monofilament fiber (BF: l: 35mm, d: 15 μm, 6.22 × 10⁶Root/kg) and glass fibers (GF: 35mm, 15 μm, 5.76 × 10⁶Root/kg) in fresh concrete with a working capacity of about 13kg/m³(ii) a Within the range of the working degree (less than or equal to 13 kg/m)³) In addition, the basalt monofilament fiber and the glass fiber have no obvious influence on the bending resistance of the concrete. Straight basalt micro-rib (SBM: l ═ 35mm, d)_e＝0.55mm、9.91×10⁴Root/kg), ribbed basalt micro-tendon (RBM: l 35mm, d_e＝0.55mm、 7.09×10⁴Root/kg), spiral basalt micro-tendon (TBM: l 35mm, d_e＝0.55mm、9.64×10⁴Root/kg) and end hook-shaped steel fibers (SF: l 35mm, d_e＝0.55mm、1.45×10⁴Root/kg) can improve the bending resistance of the concrete. The fiber mixing amount is 30kg/m³When the mid-span deflection reaches L/200(L is net span), the residual bending strength and the energy absorption value of the concrete test piece enhanced by the spiral basalt micro-bars are respectively improved by 290.0 percent and 195.1 percent compared with the flat basalt micro-bars, respectively improved by 16.4 percent and 24.6 percent compared with ribbed basalt micro-bars, and respectively improved by 33.3 percent and 41.5 percent compared with end part hook-shaped steel fibers.

The analysis shows that the spiral basalt micro-bar overcomes the defects of the application of the three types of chopped basalt fibers in concrete, can obviously improve the upper limit of the doping amount of the micro-bar in fresh concrete, obviously improves the bonding property between the micro-bar and the concrete, and further obviously improves the toughness of the concrete. In addition, compared with steel fibers, the spiral basalt micro-bar has better chloride corrosion resistance and more obvious toughening effect on concrete. Therefore, the micro-bar can be applied to concrete structures in chloride salt environments such as coastal environments, offshore environments and the like to replace or partially replace steel fibers.

The above-mentioned embodiments only express the embodiments of the present invention, but not should be understood as the limitation of the scope of the invention patent, it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the concept of the present invention, and these all fall into the protection scope of the present invention.