Device and method for improving the toughness of concrete by solving fiber agglomeration

Abstract

A process involves adding charged fibers with surface-cured temperature-sensitive gel during the preparation of concrete; preparing charged fibers with surface-cured temperature-sensitive gel by spraying, which envelops the charged fibers with a layer of temperature-sensitive gel; then solidifying the temperature-sensitive gel layer on the surface of the charged fibers by adjusting the environmental temperature. Utilizing the physical state of the temperature-sensitive gel at different temperatures, the temperature-sensitive gel wraps around the charged fibers to form an insulating layer. This prevents the scattering of the charged fibers due to charge repulsion during their introduction into the concrete preparation process, ensuring they are evenly distributed.

Claims

1. A method for improving toughness of concrete by solving fiber agglomeration, wherein charged fibers with surface-cured temperature-sensitive gel are added into a concrete to generate a high-toughness concrete; wherein the charged fibers are prepared by making a surface of a charged fiber being enveloped with a layer of the temperature-sensitive gel with a spraying process, and the layer of the temperature-sensitive gel layer is solidified by adjusting an environmental temperature.

2. The method according to claim 1, wherein a thickness of the layer of the temperature-sensitive gel layer is 1-2 mm.

3. The method according to claim 1, wherein the temperature-sensitive gel comprises carrageenan and gelatin.

4. The method according to claim 1, wherein the preparation process of the high-toughness concrete includes: S1. in terms of mass portions, put precursor powder, fine aggregate, coarse aggregate, and reinforcement components into a mixing device for dry mixing, then add charged fibers with surface-cured temperature-sensitive gel into the mixing device for dry mixing to produce dry-mixed materials; and S2. in terms of mass portions, pour the alkali-activated mixed solution into the mixing device, mix and discharge to produce high-toughness concrete.

5. The method according to claim 4, wherein the mass portions include 300-500 parts of precursor powder, 500-800 parts of fine aggregate, 700-1200 parts of coarse aggregate, 5-20 parts of reinforcement components, 10-25 parts of alkali-activated mixed solution, and charged fibers with surface-cured temperature-sensitive gel at a volume fraction of 0.1-2%; the dry mixing and stirring time is 120-180 s.

6. The method according to claim 5, wherein the precursor powder includes aluminosilicate materials, which comprise one or more types of fly ash and slag; the reinforcement component includes microsilica; the alkali-activated mixed solution is made by mixing water glass, sodium hydroxide, alkaline powder, and water at a certain mass ratio, wherein the alkaline powder is obtained by grinding, sieving, and high-temperature activation of alkaline solid waste; the fine aggregate includes river sand; and the coarse aggregate includes graded broken stone.

7. The method according to claim 6, wherein the mass ratio of water glass, sodium hydroxide, alkaline powder, and water is (2-5):(1-2):(0.5-1):(1-2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. is a schematic diagram of the structure for curing charged fibers.

(2) The labels in the drawings have the following meanings: 1, fan; 2, feeding bin; 3, charge attachment bin; 4, spraying bin; 5, curing bin; 6, feed inlet; 7, charge emitting device; 8, sprinkler head; 9, temperature control device; 10, collection bin.

DETAILED EMBODIMENT

(3) The following is a detailed introduction to the invention in combination with the drawings and specific embodiments.

(4) A method for improving the toughness of concrete by solving fiber agglomeration:

(5) The formulation of high-toughness concrete, by mass portions, consists of 300-500 parts of precursor powder, 500-800 parts of fine aggregate, 700-1200 parts of coarse aggregate, 5-20 parts of reinforcing components, 150-250 parts of alkali-activated mixed solution, and charged fibers with surface-cured temperature-sensitive gel at a volume fraction of 0.1%-2%.

(6) Precursor powder: Select and put aluminosilicate materials such as fly ash, and slag into a high-temperature furnace at 300-800? C. for high-temperature activation, quickly cool to a constant weight, then grind into powder to obtain precursor powder with certain fineness and activity, with a preferred particle size of 0.01-0.05 mm.

(7) Reinforcing components: Micro silica with an average particle size of 0.1?0.3 um.

(8) Alkali-activated mixed solution: Select alkaline solid waste slag (one or more types from calcium carbide slag, plant ash, and red mud), grind the residue, then put the ground alkaline powder into a high-temperature furnace at 350? C. for high-temperature activation to obtain alkaline powder with certain fineness and activity. Mix water glass, sodium hydroxide, alkaline powder, and water according to the mass ratio of (2-5:1-2:0.5-1:1-2), stir to prepare the alkali-activated mixed solution.

(9) Preparation of surface-cured temperature-sensitive gel:

(10) A1. Preparation device:

(11) As shown in FIG. 1, the device consists of a feeding bin, a charge attachment bin, a spraying bin, a curing bin, and a collection bin, which are connected along the transverse direction. The feeding bin has a fan at its opening, with airflow passing through the feeding bin, charge attachment bin, spraying bin, curing bin, to the collection bin in sequence.

(12) The top of the feeding bin is equipped with a feed inlet for fiber placement.

(13) The charge attachment bin is equipped with a charge emitting device to emit charges into the cavity, allowing the fiber surfaces to acquire strong like-charges, resulting in charged fibers.

(14) The top of the spraying bin is fitted with several sprinkler heads for sprinkling the temperature-sensitive gel; this allows the charged fibers to be wrapped in a layer of the temperature-sensitive gel.

(15) The curing bin is equipped with a temperature control device to regulate the internal temperature of the curing bin, causing the temperature-sensitive gel layer wrapping the charged fibers to cool and solidify.

(16) Preferably, the internal diameter of the spraying bin is not less than that of the curing bin.

(17) A2. Preparation method:

(18) Use the fan's airflow as the driving force to blow the fibers that have been placed into the feeding bin.

(19) The drifting fibers enter the charge attachment bin, where charges emitted by the charge emitting device attach strong like-charges to the fiber surfaces, creating charged fibers.

(20) Under the force of the airflow, the charged fibers drift into the spraying bin, where the sprinkler heads uniformly spray a layer of temperature-sensitive gel (carrageenan, gelatin) onto the surface of the charged fibers. By adjusting the power of the fan, the spraying duration for the charged fibers can be indirectly controlled; by regulating the spraying time, the thickness of the gel on the surface of the charged fibers can be controlled to reach 1-2 mm, achieving an effective isolation thickness.

(21) The charged fibers coated with temperature-sensitive gel drift into the curing bin under the airflow. By adjusting the temperature, the gel on the surface of the charged fibers solidifies at low temperatures, forming an insulating layer, and finally, the charged fibers with a surface-cured temperature-sensitive gel are obtained in the collection bin.

(22) Preparation method for high-toughness concrete:

(23) B1: By mass portions, weigh 300-500 parts of precursor powder, 500-800 parts of fine aggregate, 700-1200 parts of coarse aggregate, and 5-20 parts of reinforcing components into a mixing device for dry mixing for 120-180 s. Then add charged fibers with a volume fraction of 0.1%-2% surface-cured temperature-sensitive gel to the mixing device for another 120-180 s of dry mixing to evenly distribute the fibers, thus preparing the dry mixed material.

(24) B2: Pour 150-250 parts of the alkali-activated mixed solution into the mixing device all at once, and mix for 150 s. During the mixing process, under the action of friction and exothermic hydration, the insulating layer melts, releasing the charged fibers again, allowing them to be mixed into the concrete. The melted temperature-sensitive gel also mixes into the concrete, becoming a colloidal substance that aids in the concreting of the mixture; then discharge to obtain concrete mixed with charged fibers.

Example 1

(25) Mix water glass, sodium hydroxide, calcium carbide slag powder, and water in a mass ratio of 5:1.5:0.5:1 to prepare an alkali-activated mixed solution.

(26) By mass portions, take 373 parts of fly ash, 93 parts of blast furnace slag, and 10 parts of micro-silica, and dry mix for 150 s; add 681 parts of river sand and 1034 parts of graded broken stone, and dry mix for 120 s; then mix in 210 parts of the alkali-activated mixed solution and stir for 150 s before discharging.

Example 2

(27) Use carrageenan as the temperature-sensitive gel.

(28) Mix water glass, sodium hydroxide, calcium carbide slag powder, and water in a mass ratio of 5:1.5:0.5:1 to prepare an alkali-activated mixed solution.

(29) By mass portions, take 373 parts of fly ash, 93 parts of blast furnace slag, and 10 parts of micro silica, and dry mix for 150 s; add 681 parts of river sand and 1034 parts of graded broken stone, and dry mix for 120 s; then add charged fibers with a volume fraction of 2% surface-cured temperature-sensitive gel and dry mix for 150 s; next, mix in 210 parts of alkali-activated mixed solution, stir for 150 s, and then discharge.

COMPARATIVE EXAMPLE

(30) Based on the same formulation as Example 2, charge fibers with an equal amount (surface not cured temperature-sensitive gel) are added.

(31) Measure the performance of the concrete specimens obtained after standard curing from Examples 1-2 and the comparative example. Concrete performance testing: 1. Determine the compressive strength of specimens from each example according to the Standard Test Method for Mechanical Properties of Concrete GB/T50081-2019 using a 2000 kN microcomputer-controlled compression testing machine produced by Shanghai Hualong Testing Instrument Co., Ltd. Following the test specifications, the loading rate is 0.5 MPa/s, and the results are shown in Table 1. 2. Determine the splitting tensile strength of specimens from each example in accordance with the Standard Test Method for Mechanical Properties of Concrete GB/T50081-2019 using the 2000 kN microcomputer-controlled compression testing machine produced by Shanghai Hualong Testing Instrument Co., Ltd. Following the test specifications, the loading rate is 0.05 MPa/s, and the results are shown in Table 1. 3. Determine the flexural strength of specimens from each example in compliance with the Standard Test Method for Mechanical Properties of Concrete GB/T50081-2019 using the 2000 kN microcomputer-controlled compression testing machine produced by Shanghai Hualong Testing Instrument Co., Ltd. Following the test specifications, the loading rate is 0.05 MPa/s, and the results are shown in Table 1.

(32) Characterize the concrete toughness by the splitting-to-compressive ratio and flexural-to-compressive ratio. The higher these values, the greater the toughness of the concrete.

(33) TABLE-US-00001 TABLE 1 Split Compressive tensile Flexural splitting-to- flexural-to- strength/ strength/ strength/ compressive compressive MPa MPa MPa ratio ratio Example 1 41.27 3.79 5.23 0.09 0.13 Example 2 56.73 8.25 12.46 0.15 0.22 Comparative 48.46 5.73 7.25 0.12 0.15 Example

(34) For practical use, other types of temperature-sensitive gels may be selected based on the needs of the application, and the concrete formulation can be adjusted to achieve the desired performance characteristics.

(35) The above description and examples illustrate the basic principles, main features, and advantages of the present invention. Those skilled in the art will understand that the embodiments described do not limit the invention in any way. Any technical solutions obtained by equivalent substitution or transformation are within the scope of the present invention's protection.