Silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete and preparation method thereof

Abstract

The invention discloses coal gangue coarse aggregate concrete synergistically modified by a silane coupling agent and epoxy resin and a preparation method of the concrete. The preparation method of the concrete comprises the following steps: (1) pretreating coal gangue; (2) carrying out modification treatment on the pretreated coal gangue coarse aggregate by adopting a silane coupling agent; (3) carrying out modification treatment on the coal gangue coarse aggregate modified by the silane coupling agent again by adopting epoxy resin; and (4) preparing the coal gangue coarse aggregate concrete synergistically modified by the silane coupling agent and the epoxy resin. According to the invention, the coal gangue coarse aggregate is synergistically modified by the silane coupling agent and the epoxy resin to form a high-strength and low-brittleness composite material, so that the bonding performance of the composite material with a cement matrix is improved, and further the mechanical properties such as compression resistance of the prepared concrete are enhanced; the problems that coal gangue concrete in the prior art is unstable in performance and limited in application range are solved.

Description

Technical Field

[0001] This invention belongs to the field of building material resource utilization technology. Specifically, this invention relates to a silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate concrete and its preparation method. Background Technology

[0002] Currently, coal gangue, as a waste mineral resource, is often used to replace part of the aggregate in concrete preparation. However, the poor mechanical properties of coal gangue result in low overall structural strength and insufficient compressive strength in coal gangue concrete, limiting its application in construction engineering. The performance of coal gangue concrete is affected by the particle morphology, pore structure, and surface physicochemical properties of coal gangue. In particular, the high brittleness and porosity of coal gangue make the mechanical properties of the concrete unable to meet the actual engineering requirements.

[0003] Currently, in order to improve the strength of coal gangue, physical modification technology, chemical modification technology, and polymer coating or filling modification technology are commonly used to modify coal gangue.

[0004] Physical modification techniques primarily involve high-temperature calcination of coal gangue to activate clay minerals, increasing its strength and removing volatile substances from internal pores, thus reducing water absorption. Calcinated coal gangue can also partially form pozzolanic activity, enhancing its interfacial bonding with cement paste. Mechanical grinding can further refine coal gangue particles, making their morphology more regular, reducing porosity, and increasing aggregate strength. Finally, autoclaving can optimize coal gangue aggregates by using high-temperature, high-pressure steam treatment to promote the formation of active components (such as hydrated calcium silicate), improving its hardness and mechanical properties. However, high-temperature calcination requires significant energy, and poor temperature control can easily lead to increased brittleness in the coal gangue aggregate. Furthermore, mechanical grinding consumes a large amount of energy, and excessive grinding can result in an overly smooth surface, reducing adhesion to cement paste. Autoclaving modification requires specialized equipment, is costly, and has limited applicability.

[0005] Chemical modification technology mainly involves soaking coal gangue in acid or alkali solutions to enhance its surface activity, remove impurities, and improve its compatibility with cement. However, chemical modification technology uses a large number of chemical solutions, and the modification process may also generate harmful gases and waste liquid pollution, which requires treatment. This not only may cause environmental pollution but also increase post-treatment costs.

[0006] Polymer coating or filling modification technology mainly involves forming a protective layer on the surface of coal gangue using polymers such as polyurethane and acrylic acid. This improves the compressive strength of the coal gangue while reducing water absorption and pulverization tendency, effectively enhancing the bond between coal gangue and cement and reducing microcracks in the interfacial transition zone. Alternatively, filling the pores of coal gangue aggregate with water glass, silicate cement slurry, or ultrafine fly ash can reduce porosity, increase density, and enhance aggregate strength. However, the construction process for polymer coating or filling modification technology is relatively complex, requiring proper control of the polymer coating thickness; otherwise, it may affect the bond between the coal gangue aggregate and cement. For filler modification, the permeability needs precise control; otherwise, it may affect the uniformity of the aggregate itself.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] This invention proposes a method for preparing coal gangue coarse aggregate concrete synergistically modified with silane coupling agent and epoxy resin, aiming to effectively solve the technical problems of low strength and poor adhesion between coal gangue and cement through the synergistic modification of silane coupling agent and epoxy resin.

[0009] One embodiment of the present invention proposes a method for preparing coal gangue coarse aggregate concrete synergistically modified with silane coupling agent and epoxy resin, comprising the following steps:

[0010] (1) The coal gangue is mechanically crushed and screened to obtain coal gangue coarse aggregate; then the coal gangue coarse aggregate is soaked in an acidic solution, dried, and then placed in water for wetting treatment to obtain pretreated coal gangue coarse aggregate.

[0011] (2) The silane coupling agent is dissolved in ethanol to obtain a silane coupling agent-ethanol solution, and then hydrolyzed under water bath conditions; then, the pretreated coal gangue coarse aggregate is impregnated into the hydrolysis reaction product, ultrasonically assisted mixing is performed, and after drying, silane coupling agent modified coal gangue coarse aggregate is obtained.

[0012] (3) Mix epoxy resin and curing agent to obtain epoxy resin-curing agent mixture; then soak the silane coupling agent modified coal gangue coarse aggregate in the epoxy resin-curing agent mixture, stir and mix, and then perform vacuum heat treatment and heat curing to obtain silane coupling agent and epoxy resin synergistic modified coal gangue coarse aggregate.

[0013] (4) The silane coupling agent and epoxy resin synergistic modified coal gangue coarse aggregate is dry-mixed with cement, fly ash, natural river sand, natural aggregate and water-reducing agent, and then water is added for wet mixing; then the resulting mixture is poured into a mold and placed on a vibrating table for vibration; then it is covered with plastic wrap for static treatment, and finally demolded and cured to obtain the silane coupling agent and epoxy resin synergistic modified coal gangue coarse aggregate concrete.

[0014] In some embodiments, in step (1), the particle size of the coarse coal gangue aggregate is 5 to 20 mm;

[0015] And / or, the acidic solution is a hydrochloric acid solution with a concentration of 0.1–1 mol / L;

[0016] And / or, the soaking treatment time is 30 to 40 minutes;

[0017] And / or, the wetting treatment time is 1 to 2 hours.

[0018] In some embodiments, in step (2), the silane coupling agent is an epoxy-type silane coupling agent;

[0019] Optionally, the epoxy-type silane coupling agent includes at least one of silane coupling agent KH-560 and silane coupling agent KH-570;

[0020] And / or, the mass ratio of the silane coupling agent to the pretreated coal gangue coarse aggregate is (0.5-3):(100-102).

[0021] In some embodiments, in step (2), the reaction temperature of the hydrolysis reaction is 50-55°C and the reaction time is 30-40 min;

[0022] And / or, the immersion time is 10 to 15 minutes;

[0023] And / or, the drying temperature is 80-85°C, and the drying time is 2-3 hours.

[0024] In some embodiments, in step (3), the epoxy resin is a highly permeable liquid epoxy resin;

[0025] Optionally, the highly permeable liquid epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and waterborne epoxy resin emulsion;

[0026] And / or, the curing agent includes at least one of polyamide 650, polyamide 651, and polyetheramine D230;

[0027] And / or, the mass ratio of the epoxy resin to the curing agent is (90-100):(30-80).

[0028] In some embodiments, in step (3), the mass ratio of the silane coupling agent modified coal gangue coarse aggregate to the epoxy resin is (88-92):(1-1.2).

[0029] In some embodiments, in step (3), the mixing time is 10 to 12 minutes;

[0030] And / or, the temperature of the vacuum heat treatment is 80–90°C;

[0031] And / or, the thermosetting temperature is 60-65°C and the time is 2-4 hours.

[0032] In some embodiments, in step (4), the dry mixing time is 60-80 seconds;

[0033] And / or, the wet mixing time is 4 to 5 minutes.

[0034] In some embodiments, in step (4), the curing temperature is 20±2℃ and the humidity is ≥95%.

[0035] Another aspect of this invention provides a silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate concrete, wherein the silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate concrete is prepared by the above-described preparation method.

[0036] The advantages and beneficial effects of the embodiments of the present invention are as follows:

[0037] (1) In this embodiment of the invention, silane coupling agent and epoxy resin are used to synergistically modify coal gangue coarse aggregate, which can improve the adhesion between inorganic materials (cement-based) and organic materials (epoxy resin-based), and optimize the interface transition zone between coal gangue coarse aggregate and cement, effectively reducing the internal porosity of coal gangue coarse aggregate concrete, improving its density and mechanical strength. The modified coal gangue coarse aggregate is more tightly bonded to the cement matrix interface, thereby effectively improving the compressive strength of the obtained concrete.

[0038] (2) The preparation method of the present invention realizes the efficient utilization of coal gangue solid waste, turning waste into treasure. It can not only reduce the consumption of natural aggregate resources and alleviate the pressure of natural aggregate resource depletion, but also reduce the harm of coal gangue solid waste to the environment and reduce carbon emissions. It can also reduce production costs and has significant social value and economic benefits.

[0039] (3) The preparation method of the present invention is more operable in terms of technical implementation, does not require complex equipment and process flow, has strong controllability, and is easy to promote and apply on a large scale in industrial applications. Attached Figure Description

[0040] Figure 1 This is a microstructure diagram of the coal gangue coarse aggregate concrete synergistically modified by silane coupling agent and epoxy resin obtained in Example 1 of the present invention.

[0041] Figure 2 This is a microstructure diagram of the epoxy resin-modified coal gangue coarse aggregate concrete of control group 1.

[0042] Figure 3 The values ​​represent the compressive strength of coal gangue coarse aggregate concrete synergistically modified with silane coupling agent and epoxy resin, and coal gangue coarse aggregate concrete modified with epoxy resin alone, after 3 days of curing.

[0043] Figure 4 The values ​​represent the compressive strength of coal gangue coarse aggregate concrete synergistically modified with silane coupling agent and epoxy resin, and coal gangue coarse aggregate concrete modified with epoxy resin alone, after 7 days of curing.

[0044] Figure 5 The values ​​represent the compressive strength of coal gangue coarse aggregate concrete synergistically modified with silane coupling agent and epoxy resin, and coal gangue coarse aggregate concrete modified with epoxy resin alone, after 28 days of curing. Detailed Implementation

[0045] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0046] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​that fall within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0047] In this article, the words “contain” and “include” and their various variations mean that other elements or wholes may be included but not specifically described.

[0048] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone.

[0049] One embodiment of the present invention proposes a method for preparing coal gangue coarse aggregate concrete synergistically modified with silane coupling agent and epoxy resin, comprising the following steps:

[0050] (1) Coal gangue pretreatment: The coal gangue is mechanically crushed and screened to obtain coal gangue coarse aggregate; then the coal gangue coarse aggregate is soaked in an acidic solution, dried, and then placed in water for wetting treatment to obtain pretreated coal gangue coarse aggregate.

[0051] (2) Modification of coal gangue coarse aggregate using silane coupling agent: Dissolve silane coupling agent in ethanol to obtain silane coupling agent-ethanol solution, and then perform hydrolysis reaction under water bath conditions; after that, impregnate the pretreated coal gangue coarse aggregate into the hydrolysis reaction product, mix with ultrasonic assistance, and dry to obtain silane coupling agent modified coal gangue coarse aggregate;

[0052] (3) The coarse aggregate of coal gangue modified with epoxy resin is further modified: epoxy resin and curing agent are mixed to obtain epoxy resin-curing agent mixture; the coarse aggregate of coal gangue modified with epoxy resin is then immersed in the epoxy resin-curing agent mixture, stirred and mixed, and then subjected to vacuum heat treatment and heat curing to obtain coarse aggregate of coal gangue synergistically modified with epoxy resin and epoxy resin.

[0053] (4) Preparation of silane coupling agent and epoxy resin synergistic modified coal gangue coarse aggregate concrete: The silane coupling agent and epoxy resin synergistic modified coal gangue coarse aggregate is dry-mixed with cement, fly ash, natural river sand, natural aggregate and water-reducing agent, and then water is added for wet mixing; then the resulting mixture is poured into a mold and placed on a vibrating table for vibration; then it is covered with plastic wrap for static treatment, and finally demolded and cured to obtain the silane coupling agent and epoxy resin synergistic modified coal gangue coarse aggregate concrete.

[0054] This invention employs a silane coupling agent and epoxy resin to synergistically modify coal gangue coarse aggregate. The silane coupling agent forms active functional groups on the coal gangue surface, improving its surface activity and enhancing its chemical bonding with the epoxy resin and its interfacial adhesion to the cement matrix. The epoxy resin, on the other hand, forms a stable chemical cross-linked network structure, thereby improving the hardness, wear resistance, and other mechanical properties of the coal gangue, as well as its mechanical bonding force with the cement matrix. This significantly enhances the compressive strength and other mechanical properties of coal gangue concrete. This synergistic modification method effectively solves the problem of insufficient interfacial adhesion between coal gangue and the cement matrix, thus improving the overall mechanical properties and durability of concrete and reducing cracking caused by insufficient interfacial adhesion. Compared to existing single modification technologies, this synergistic modification method not only improves the inherent strength of the coal gangue aggregate but also enhances the interfacial adhesion between the aggregate and cement, thereby improving the mechanical properties of the concrete.

[0055] Furthermore, this invention utilizes silane coupling agents and epoxy resins to synergistically modify coal gangue coarse aggregate to prepare concrete. On one hand, this improves the utilization rate of coal gangue, reduces its environmental harm, and lowers carbon emissions, thus having a positive impact on the environment. On the other hand, using coal gangue to replace natural aggregates can reduce the mining of natural aggregate resources, effectively alleviating the pressure of natural aggregate depletion. In addition, as a cheap waste resource, adding coal gangue to concrete helps reduce concrete production costs. Moreover, the resulting concrete can meet the strength requirements for practical applications and can be used in non-load-bearing components of roads and buildings, which has important demonstrative significance for promoting the low-carbon transformation of the construction industry.

[0056] In some embodiments, in step (1), the particle size of the coarse coal gangue aggregate is 5 to 20 mm;

[0057] And / or, the acidic solution is a hydrochloric acid solution with a concentration of 0.1 to 1 mol / L; the soaking time is 30 to 40 min; by soaking the coarse coal gangue aggregate with hydrochloric acid solution, impurities on the surface of the coarse coal gangue aggregate can be removed and its activity reduced, thus avoiding adverse effects on the interior of the material when it is used as concrete aggregate.

[0058] And / or, the wetting treatment time is 1 to 2 hours; by immersing the coarse coal gangue aggregate in water for wetting treatment, the pore structure of the coarse coal gangue aggregate can be filled, its water absorption rate can be reduced, thereby avoiding problems such as incomplete cement hydration.

[0059] In some embodiments, in step (2), the silane coupling agent is an epoxy-type silane coupling agent;

[0060] Optionally, the epoxy-type silane coupling agent includes at least one of silane coupling agent KH-560 and silane coupling agent KH-570;

[0061] And / or, the mass ratio of the silane coupling agent to the pretreated coal gangue coarse aggregate is (0.5-3):(100-102).

[0062] This invention preferably uses an epoxy-based silane coupling agent to modify coal gangue coarse aggregate. This is primarily because epoxy-based silane coupling agents possess high permeability and high adhesion, allowing them to more easily fill the micron-level pore structure of coal gangue during modification. They also effectively isolate corrosive media such as moisture and chloride ions, indirectly improving the durability of concrete. Furthermore, the inventors have discovered that excessive silane coupling agent addition not only increases production costs but also leads to multilayer physical adsorption of excess silane coupling agent after the coal gangue particles become saturated, or introduces weak layers at the interface, resulting in a decrease in the performance of the resulting composite material. Conversely, insufficient silane coupling agent addition prevents complete coating of the coal gangue particle surface, resulting in minimal improvement in the mechanical properties of the composite material. Therefore, it is advantageous in this embodiment of the invention to control the mass ratio of silane coupling agent to pretreated coal gangue coarse aggregate within the range of (0.5-3):(100-102).

[0063] In some embodiments, in step (2), the reaction temperature of the hydrolysis reaction is 50-55°C and the reaction time is 30-40 min;

[0064] And / or, the immersion time is 10 to 15 minutes;

[0065] And / or, the drying temperature is 80-85°C, and the drying time is 2-3 hours.

[0066] In some embodiments, in step (3), the epoxy resin is a highly permeable liquid epoxy resin;

[0067] Optionally, the highly permeable liquid epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and waterborne epoxy resin emulsion;

[0068] And / or, the curing agent includes at least one of polyamide 650, polyamide 651, and polyetheramine D230;

[0069] And / or, the mass ratio of the epoxy resin to the curing agent is (90-100):(30-80).

[0070] In this embodiment of the invention, a highly permeable liquid epoxy resin is preferred for modifying coal gangue coarse aggregate. This type of epoxy resin has high permeability and high adhesion, enabling it to better fill the micropores inside the coal gangue. Furthermore, the inventors have discovered that if the amount of curing agent added is too high, the resulting composite material will have an excessively high crosslinking density, significantly increasing its brittleness. Simultaneously, residual unreacted curing agent will affect the strength and durability of the composite material. However, if the amount of curing agent added is too low, incomplete curing will result, and the modified layer will fail to provide reinforcement and protection. Therefore, in this embodiment of the invention, the mass ratio of epoxy resin to curing agent is controlled within the range of (90–100):(30–80).

[0071] In some embodiments, in step (3), the mass ratio of the silane coupling agent-modified coal gangue coarse aggregate to the epoxy resin is (88-92):(1-1.2). If the amount of epoxy resin added is too high, it will not only increase costs but also increase the brittleness of the material, negatively impacting the mechanical properties of the concrete. However, if the amount of epoxy resin added is too low, it will cause the coal gangue to fail to bond properly, resulting in a relatively loose structure that cannot effectively transfer stress, thus affecting the mechanical properties and durability of the concrete.

[0072] In some embodiments, in step (3), the mixing time is 10 to 12 minutes;

[0073] And / or, the temperature of the vacuum heat treatment is 80-90°C; vacuum heat treatment can help remove air bubbles inside the modified coal gangue coarse aggregate, avoid stress concentration points, and prevent the mechanical properties of the composite material from being reduced.

[0074] And / or, the thermosetting temperature is 60-65°C and the time is 2-4 hours.

[0075] In some embodiments, in step (4), the dry mixing time is 60-80 seconds;

[0076] And / or, the wet mixing time is 4 to 5 minutes.

[0077] In some embodiments, in step (4), the curing temperature is 20±2℃ and the humidity is ≥95%.

[0078] It should be noted that the water used in the preparation method of this invention is all tap water.

[0079] Another aspect of this invention provides a silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate concrete, which is prepared by the above-described method. This concrete can achieve the strength requirements of C30 concrete and can be better applied in some low-strength buildings or roads.

[0080] The following are non-limiting embodiments and comparative examples of the present invention. It should be noted that the schemes in the comparative examples are not prior art, but are only set up for comparison with the schemes in the embodiments, and are not intended to limit the present invention. Unless otherwise stated, all raw materials used in the embodiments and comparative examples are conventional commercially available products, or can be prepared by known methods.

[0081] It should be noted that, in the embodiments of the present invention, the coal gangue replacement rate = the mass of the coal gangue coarse aggregate synergistically modified by silane coupling agent and epoxy resin / the sum of the masses of (coal gangue coarse aggregate synergistically modified by silane coupling agent and epoxy resin + natural aggregate).

[0082] Example 1

[0083] This embodiment provides a method for preparing coal gangue coarse aggregate concrete synergistically modified with silane coupling agent and epoxy resin, including the following steps:

[0084] (1) Coal gangue pretreatment: The blocky coal gangue is mechanically crushed and screened to obtain coarse coal gangue aggregate with a particle size of 5-20mm; then the coarse coal gangue aggregate is soaked in a 0.5mol / L hydrochloric acid solution for 30min to remove surface impurities and reduce its activity. Then the coarse coal gangue aggregate is put into a dryer and dried to constant weight. After that, it is placed in water and moistened for 1h to obtain pretreated coarse coal gangue aggregate.

[0085] (2) Modification of coal gangue coarse aggregate using silane coupling agent: Dissolve silane coupling agent KH-560 in ethanol to obtain silane coupling agent-ethanol solution, and then hydrolyze it in a 50℃ water bath for 30 min to generate active silanol groups; then, impregnate the pretreated coal gangue coarse aggregate into the hydrolysis reaction product (wherein, the mass ratio of silane coupling agent KH-560 to pretreated coal gangue coarse aggregate is 1:100), mix with ultrasonic assistance for 10 min to ensure that the surface is fully wetted, drain and then dry at 80℃ for 2 h to form a chemically bonded coupling layer, thus obtaining silane coupling agent modified coal gangue coarse aggregate;

[0086] (3) The coarse aggregate of coal gangue modified with silane coupling agent was further modified with epoxy resin: Bisphenol A type epoxy resin and polyamide 650 were mixed at a mass ratio of 100:60 to obtain epoxy resin-curing agent mixture; the coarse aggregate of coal gangue modified with silane coupling agent was then immersed in epoxy resin-curing agent mixture (wherein, the mass ratio of coarse aggregate of coal gangue modified with silane coupling agent to bisphenol A type epoxy resin was 88:1), stirred and mixed for 10 min, and then vacuum heat treated at 80℃ to help remove air bubbles, and then heat cured at 60℃ for 3 h to form a dense resin coating layer, thus obtaining coarse aggregate of coal gangue modified with silane coupling agent and epoxy resin.

[0087] (4) Preparation of coal gangue coarse aggregate concrete synergistically modified with silane coupling agent and epoxy resin: 624 kg / m³ of coal gangue coarse aggregate synergistically modified with silane coupling agent and epoxy resin. 3 With cement 321.6kg / m 3 fly ash 80.4 kg / m³ 3 740kg / m³ of natural river sand 3 416 kg / m³ of natural aggregate 3 Polycarboxylate superplasticizer 0.804 kg / m 3 Dry mix for 60 seconds, then add 155 kg / m³ of water. 3 Mix wet for 4 minutes until homogeneous; then pour the resulting mixture into a mold (100mm*100mm*100mm cube) pre-coated with release agent and cast it into shape. After that, place it on a vibrating table to vibrate and ensure the concrete is completely filled. Then cover it with plastic wrap and let it stand for 1 day to prevent moisture evaporation. After demolding, place the test block in a standard curing room (temperature 20±2°C, humidity ≥95%) for curing. This will yield silane coupling agent and epoxy resin co-modified coal gangue coarse aggregate concrete with a substitution rate of 40% (wherein, substitution rate = mass of silane coupling agent and epoxy resin co-modified coal gangue coarse aggregate / (mass of silane coupling agent and epoxy resin co-modified coal gangue coarse aggregate + natural aggregate)).

[0088] Control group 1

[0089] Control group 1 provides a method for preparing epoxy resin-modified coal gangue coarse aggregate concrete. The preparation process is basically the same as that of Example 1, except that: control group 1 does not include step (2) of Example 1, and in step (3), “silane coupling agent modified coal gangue coarse aggregate” should be replaced with “pretreated coal gangue coarse aggregate”; in steps (3) and (4), “silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate” should be replaced with “epoxy resin-modified coal gangue coarse aggregate”.

[0090] The microstructure of concrete prepared in Example 1 and Control Group 1 was analyzed using scanning electron microscopy. A cubic block with approximately 10 mm sides was taken from the center of the specimen, vacuum degassed, and then gold-plated on the surface for observation. The results are shown in the figures below. Figure 1 and Figure 2 As shown.

[0091] from Figure 2 As can be seen, concrete made by using epoxy resin to modify coal gangue coarse aggregate alone exhibits multiple cracks at the interface transition zone between the coal gangue coarse aggregate and cement. These cracks directly affect the mechanical properties of the concrete. In contrast, the concrete made by using silane coupling agent and epoxy resin to synergistically modify coal gangue coarse aggregate in this invention (…) Figure 1 The interface between the coarse aggregate of coal gangue and cement is smoother, and there are no obvious cracks as in the case of separate modification. This is mainly because the silane coupling agent acts as a "bridge", which enables the aggregate and cement to have better bonding performance, thus having a positive impact on the mechanical properties of concrete.

[0092] The slump and 28-day compressive strength of the concrete prepared by silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate in Example 1 (wherein the substitution rate of coal gangue coarse aggregate synergistic modification by silane coupling agent and epoxy resin is 40%) and the concrete prepared by control group 1 using epoxy resin alone to modify coal gangue coarse aggregate with an epoxy resin alone modification rate of 40% were tested. The results are shown in Table 1.

[0093] Table 1

[0094]

[0095] Note: CGC-A-40% represents concrete prepared when epoxy resin alone modifies coal gangue coarse aggregate with a replacement rate of 40%; CGC-B-40% represents concrete prepared when silane coupling agent and epoxy resin synergistically modify coal gangue coarse aggregate with a replacement rate of 40%.

[0096] As shown in Table 1, when the coal gangue replacement rate is 40%, the slump of the epoxy resin-modified coal gangue coarse aggregate concrete is 237 mm, and the 3-day, 7-day, and 28-day compressive strengths are 15.31 MPa, 23.49 MPa, and 39.42 MPa, respectively. In contrast, the slump of the silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete is 231 mm, and the 3-day, 7-day, and 28-day compressive strengths are 16.48 MPa, 26.72 MPa, and 42.03 MPa, respectively. Therefore, compared to the control group concrete made with epoxy resin-modified coal gangue coarse aggregate alone, the concrete of this embodiment, made with silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate, has a slump reduced by 6 mm and a compressive strength increased by 6.6%.

[0097] Example 2

[0098] This embodiment is basically the same as Embodiment 1, except that in step (4) of this embodiment, the amount of silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate added is 416 kg / m³. 3 The amount of natural aggregate added is 624 kg / m³. 3 That is, the synergistic modification of coal gangue coarse aggregate by silane coupling agent and epoxy resin resulted in a replacement rate of 60%.

[0099] Control group 2

[0100] Control group 2 was essentially the same as control group 1, except that the amount of epoxy resin-modified coal gangue coarse aggregate added in control group 2 was 416 kg / m³. 3 The amount of natural aggregate added is 624 kg / m³. 3 That is, the replacement rate of coarse aggregate from coal gangue modified with epoxy resin alone is 60%.

[0101] The slump and 28-day compressive strength of the concrete prepared by silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate in Example 2 (where the silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate replacement rate is 60%) and the concrete prepared by control group 2 using epoxy resin alone to modify coal gangue coarse aggregate with epoxy resin alone modification of coal gangue coarse aggregate replacement rate of 60% were tested, and the results are shown in Table 2.

[0102] Table 2

[0103]

[0104] Note: CGC-A-60% represents concrete prepared when epoxy resin alone modifies coal gangue coarse aggregate with a replacement rate of 60%; CGC-B-60% represents concrete prepared when silane coupling agent and epoxy resin synergistically modify coal gangue coarse aggregate with a replacement rate of 60%.

[0105] As shown in Table 2, when the coal gangue replacement rate is 60%, the slump of the epoxy resin-modified coal gangue coarse aggregate concrete is 220 mm, and the 3-day, 7-day, and 28-day compressive strengths are 14.01 MPa, 19.76 MPa, and 34.92 MPa, respectively. In contrast, the slump of the silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete is 213 mm, and the 3-day, 7-day, and 28-day compressive strengths are 16.72 MPa, 23.43 MPa, and 38.44 MPa, respectively. Therefore, compared to the control group concrete made with epoxy resin-modified coal gangue coarse aggregate, the concrete of this embodiment, made with silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate, has a slump reduced by 7 mm and a compressive strength increased by 10.1%.

[0106] Example 3

[0107] This embodiment is basically the same as Embodiment 1, except that in step (4) of this embodiment, the amount of silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate added is 832 kg / m³. 3 The amount of natural aggregate added is 208 kg / m³. 3 That is, the synergistic modification of coal gangue coarse aggregate by silane coupling agent and epoxy resin resulted in a replacement rate of 80%.

[0108] Control group 3

[0109] Control group 3 was basically the same as control group 1, except that the amount of epoxy resin-modified coal gangue coarse aggregate added in control group 3 was 832 kg / m³. 3 The amount of natural aggregate added is 208 kg / m³. 3 That is, the replacement rate of coarse aggregate from coal gangue modified with epoxy resin alone is 80%.

[0110] The slump and 28-day compressive strength of the concrete prepared by silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate in Example 3 (where the silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate replacement rate is 80%) and the concrete prepared by control group 3 using epoxy resin alone to modify coal gangue coarse aggregate with epoxy resin alone modification of coal gangue coarse aggregate replacement rate of 80% were tested, and the results are shown in Table 3.

[0111] Table 3

[0112]

[0113] Note: CGC-A-80% represents concrete prepared when epoxy resin alone modifies coal gangue coarse aggregate and the replacement rate is 80%; CGC-B-80% represents concrete prepared when silane coupling agent and epoxy resin synergistically modify coal gangue coarse aggregate and the replacement rate is 80%.

[0114] As shown in Table 3, when the coal gangue replacement rate is 80%, the slump of the epoxy resin-modified coal gangue coarse aggregate concrete is 210 mm, and the 3-day, 7-day, and 28-day compressive strengths are 11.92 MPa, 15.99 MPa, and 28.12 MPa, respectively. In contrast, the slump of the silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete is 201 mm, and the 3-day, 7-day, and 28-day compressive strengths are 13.98 MPa, 19.72 MPa, and 35.66 MPa, respectively. The comparison shows that, compared to the control group concrete made with epoxy resin-modified coal gangue coarse aggregate, the concrete of this embodiment using silane coupling agent and epoxy resin synergistic modification of coal gangue coarse aggregate has a slump reduced by 9 mm and a compressive strength increased by 26.8%.

[0115] Control group 4

[0116] This control group 4 provides a method for preparing concrete using natural aggregates, including the following steps:

[0117] 321.6 kg / m³ of cement 3 fly ash 80.4 kg / m³ 3 740kg / m³ of natural river sand 3 1040 kg / m³ of natural aggregate 3 Polycarboxylate superplasticizer 0.804 kg / m 3 First, dry mix for 60 seconds, then add 155 kg / m³ of water. 3 Mix wet for 4 minutes until homogeneous; then pour the resulting mixture into a mold (100mm*100mm*100mm cube) that has been pre-coated with a release agent and cast it into shape. After that, place it on a vibrating table to vibrate it so that the concrete is completely filled inside. Then cover it with plastic wrap and let it stand for 1 day to prevent moisture evaporation. After demolding, place the test block in a standard curing room (temperature 20±2°C, humidity ≥95%) for curing to obtain concrete made from natural aggregates.

[0118] The slump and compressive strength of the concrete obtained in this control group were tested, and the results are shown in Table 4.

[0119] Table 4

[0120]

[0121] Comparing Table 4 and Table 1-2, it can be seen that, with comparable content of raw materials such as cement, the concrete prepared by using silane coupling agent and epoxy resin to synergistically modify coal gangue coarse aggregate in Examples 1-3 of this invention has a lower slump than the concrete prepared by natural aggregate in Control Group 4. Furthermore, regarding compressive strength, when the coal gangue replacement rate is 40% and 60%, the early strength of the concrete prepared by silane coupling agent and epoxy resin to synergistically modify coal gangue coarse aggregate is higher than that of ordinary concrete prepared using natural aggregate, with 7-day compressive strength increases of 16.8% and 2.4%, respectively. Furthermore, when the coal gangue replacement rate is 40%, the concrete prepared by using silane coupling agent and epoxy resin to synergistically modify coal gangue coarse aggregate still has a higher 28-day compressive strength than ordinary concrete prepared by using natural aggregate. This further illustrates the feasibility of using silane coupling agent and epoxy resin to synergistically modify coal gangue coarse aggregate to replace natural aggregate in the preparation of high-performance concrete, and provides a new approach for the recycling of waste coal gangue and the preparation of green concrete.

[0122] Macroscopic mechanical properties were tested on the silane coupling agent and epoxy resin synergistic modified coal gangue coarse aggregate concrete prepared in Examples 1-3, the epoxy resin-modified coal gangue coarse aggregate concrete prepared in Control Groups 1-3, and the concrete prepared using natural aggregate in Control Group 4. Specifically, compressive strength tests were conducted on the specimens according to the relevant provisions of GB / T50081—2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". A TYA-2000 compression testing machine was used, and a loading rate of 0.5 MPa / s was applied until the specimen failed. The recorded failure load was converted into the standard specimen strength, with a conversion factor of 0.95. The compressive strength values ​​of the coal gangue concrete at 3d, 7d, and 28d were finally measured. Figure 3-5 As shown.

[0123] from Figure 3-5As can be seen, compared to using epoxy resin alone to modify coal gangue coarse aggregate to prepare concrete, the embodiments of this invention, by using silane coupling agent and epoxy resin to synergistically modify coal gangue coarse aggregate, can reduce the slump of coal gangue concrete, resulting in better workability. Furthermore, the synergistic modification leads to higher compressive strength in the concrete compared to modifying coal gangue coarse aggregate alone. At low coal gangue replacement rates, the early strength is approximately equal to that of ordinary concrete, while at high coal gangue replacement rates, the compressive strength shows varying degrees of improvement. The main reason for the improved mechanical properties of coal gangue concrete under the synergistic modification technology is that coating the surface of the coal gangue with epoxy resin, which modifies the silane coupling agent, creates a dense coating layer on the surface of the coarse aggregate, reducing the inherent defects of high porosity and high water absorption in coal gangue. Furthermore, by using silane coupling agents as a "bridge" to connect with cement, epoxy resin organic materials and cement-based inorganic materials can be better connected, thereby improving the bonding state of the interface transition zone between modified coal gangue and cement, which will have a positive effect on the mechanical properties of coal gangue concrete.

[0124] Compared to existing individual modification techniques, the method of this invention can not only improve the strength of the coal gangue coarse aggregate itself, but also enhance the interfacial bond between the aggregate and cement, thereby improving the mechanical properties of the resulting concrete. Furthermore, this invention uses solid waste coal gangue as aggregate, turning waste into treasure. This not only reduces the consumption of natural aggregate resources, but also avoids the environmental harm caused by coal gangue solid waste, while reducing production costs, demonstrating high environmental value and economic benefits. It also provides a new way to recycle and utilize waste coal gangue, meeting the needs of today's green building and sustainable development.

[0125] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0126] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete, characterized in that, The method comprises the following steps: (1) mechanically crushing and screening coal gangue to obtain coal gangue coarse aggregate; then soaking the coal gangue coarse aggregate in an acidic solution, drying, and then wetting the coal gangue coarse aggregate in water to obtain pretreated coal gangue coarse aggregate; (2) dissolving a silane coupling agent in ethanol to obtain a silane coupling agent-ethanol solution, and then performing a hydrolysis reaction in a water bath; Then, the pretreated coal gangue coarse aggregate is immersed in the hydrolysis reaction product, ultrasonic-assisted mixing, and drying to obtain silane coupling agent-modified coal gangue coarse aggregate; (3) mixing an epoxy resin and a curing agent to obtain an epoxy resin-curing agent mixture; then soaking the silane coupling agent-modified coal gangue coarse aggregate in the epoxy resin-curing agent mixture, stirring and mixing, and then performing vacuum heat treatment and heat curing to obtain silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate; (4) dry mixing the silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate with cement, fly ash, natural river sand, natural aggregate, and water reducing agent, and then wet mixing; then pouring the obtained mixture into a mold and placing it on a vibration table for vibration; then covering it with plastic wrap and placing it for static treatment, and finally demolding and curing to obtain the silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete.

2. The method for preparing silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete according to claim 1, characterized in that, In step (1), the particle size of the coal gangue coarse aggregate is 5-20 mm; And / or, the acidic solution is a hydrochloric acid solution with a concentration of 0.1-1 mol / L; And / or, the soaking time is 30-40 min; And / or, the wetting time is 1-2 h.

3. The method for preparing silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete according to claim 1, characterized in that, In step (2), the silane coupling agent is an epoxy-based silane coupling agent; Optionally, the epoxy-based silane coupling agent includes at least one of silane coupling agent KH-560 and silane coupling agent KH-570; And / or, the mass ratio of the silane coupling agent to the pretreated coal gangue coarse aggregate is (0.5-3):(100-102).

4. The method for preparing silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete according to claim 1, characterized in that, In step (2), the reaction temperature of the hydrolysis reaction is 50-55℃, and the reaction time is 30-40 min; And / or, the immersion time is 10-15 min; And / or, the drying temperature is 80-85℃, and the drying time is 2-3 h.

5. The method for preparing silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete according to claim 1, characterized in that, In step (3), the epoxy resin is a high-permeability liquid epoxy resin; Optionally, the high-permeability liquid epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and water-based epoxy resin emulsion; And / or, the curing agent includes at least one of polyamide 650, polyamide 651, and polyether amine D230; And / or, the mass ratio of the epoxy resin to the curing agent is (90-100):(30-80).

6. The method for preparing the silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete according to claim 1 or 5, characterized in that, In step (3), the mass ratio of the silane coupling agent-modified coal gangue coarse aggregate to the epoxy resin is (88-92):(1-1.2).

7. The method for preparing silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete according to claim 1, characterized in that, In the step (3), the time of the stirring mixing is 10-12 min; and / or, the temperature of the vacuum heat treatment is 80-90℃; and / or, the temperature of the heat curing is 60-65℃, and the time is 2-4 h.

8. The method for preparing silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete according to claim 1, characterized in that, In the step (4), the time of the dry mixing is 60-80 s; and / or, the time of the wet mixing is 4-5 min.

9. The method for preparing silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete according to claim 1, characterized in that, In the step (4), the temperature of the curing is 20±2℃, and the humidity is ≥95%.

10. A silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete, characterized by, The silane coupling agent and epoxy resin synergistically modified coal gangue coarse aggregate concrete is prepared by the preparation method of any one of claims 1-9.

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