Basalt fiber and rubber particle modified and reinforced Portland cement and preparation method thereof

Abstract

The invention discloses basalt fiber and rubber particle modified and reinforced Portland cement and a preparation method thereof, and relates to reinforced Portland cement and a preparation method thereof. The reinforced Portland cement is prepared from the following components in parts by mass: 0.1 to 1 part of modified basalt fiber, 1 to 8 parts of modified rubber particles and 70 to 100 parts of Portland cement. The basalt fibers are modified, so that the surface roughness of the basalt fibers is improved, the bonding strength with a cement matrix is further improved, hydrophilic groups and grafted graphene oxide are introduced to the surfaces of the basalt fibers, and the bonding strength of the basalt fibers and the interface of the cement matrix is further enhanced. Meanwhile, the rubber particles are modified, so that the hydrophilicity of the surfaces of the rubber particles is enhanced, and the bonding strength of the rubber particles and a cement matrix is further enhanced. Through the synergistic effect of the two components, the Portland cement is enhanced, and the cement-based material is suitable for engineering scenes such as roads, bridges, airport pavements and tunnel linings which have high requirements on mechanical properties and durability of cement-based materials.

Description

Technical Field

[0001] This invention relates to a reinforced silicate cement and its preparation method, and more particularly to a basalt fiber and rubber particle modified reinforced silicate cement and its preparation method. Background Technology

[0002] Silicate cement is a core cementing material in building construction, but its inherent defects, such as high brittleness, poor crack resistance and toughness, and insufficient durability, make it difficult to meet the demands of modern engineering for high crack resistance, earthquake resistance, and long service life. To solve this problem, fiber reinforcement and lightweight particle modification have become the mainstream technical directions.

[0003] Basalt fiber is an ideal cement reinforcing material due to its high strength, high modulus, environmental friendliness, and low cost. However, unmodified fibers have a smooth surface and weak interfacial bonding with the cement matrix, making them prone to debonding and resulting in insufficient reinforcing performance. Rubber particles can improve cement toughness, and waste rubber recycling aligns with the concept of a circular economy. However, their surface inertness leads to poor compatibility with the matrix, and direct incorporation can easily reduce strength and cause segregation. The limitations of single modification have driven the exploration of synergistic technologies: modified basalt fibers can form chemical bonds with cement through active groups, bridging and suppressing microcracks; modified rubber particles can enhance interfacial bonding and absorb energy and dampen vibrations. The two form a "strength-toughness" dual-reinforcing system, complementing the shortcomings of single modification.

[0004] Current infrastructure construction places increasing demands on the comprehensive performance of materials, creating an urgent need for the resource utilization of waste rubber. However, existing technologies are mostly unmodified or involve only single-modification synergy, resulting in poor interfacial bonding and insufficient synergistic effects. Therefore, developing a synergistic enhancement technology to simultaneously improve the strength, toughness, and durability of cement while promoting the utilization of waste rubber possesses both key technological value and promising industry application prospects.

[0005] Because basalt fibers have a smooth, flat surface, their interfacial bonding with silicate cement is weak, making them susceptible to damage and separation, and they are also difficult to react chemically with other substances. Secondly, the hydrophobic nature of the rubber surface hinders the adhesion between the silicate cement matrix and the rubber surface. Summary of the Invention

[0006] The purpose of this invention is to provide a basalt fiber and rubber particle modified reinforced silicate cement and its preparation method. This invention optimizes the interfacial bonding performance between basalt fiber and rubber particles and the cement matrix by targeted composite modification. By utilizing the synergistic mechanism of fiber crack resistance and particle energy absorption, it significantly improves the flexural strength, impact resistance and crack resistance of cement while ensuring its compressive strength. At the same time, it realizes the resource utilization of waste rubber, reducing engineering costs and environmental burden.

[0007] The objective of this invention is achieved through the following technical solution: A basalt fiber and rubber particle modified reinforced silicate cement, wherein the cement comprises, by mass fraction, 0.1 to 1 part of modified basalt fiber, 1 to 8 parts of modified rubber particles, and 70 to 100 parts of silicate cement; The rubber particles have a particle size of 0.5~2.0mm and a particle size deviation of ≤0.3mm; the silicate cement is PO 42.5 grade general-purpose silicate cement, which conforms to GB 175-2007 "General-purpose Silicate Cement" standard, with a 28-day compressive strength ≥42.5MPa, an initial setting time ≥45min, and a final setting time ≤600min; the modified rubber particles have a dispersion uniformity of ≥90% in the cement matrix; the modified basalt fibers have a length of 6~12mm and a diameter of 15~25μm.

[0008] A method for preparing basalt fiber and rubber particle modified reinforced silicate cement, wherein the preparation process is as follows: The modification process of modified basalt fiber is as follows: basalt fiber is pretreated with acetone, dried and set aside for later use. The pretreated basalt fiber is then subjected to plasma treatment and reacted with graphene oxide. The modification method of modified basalt fiber is a three-stage composite modification of acetone pretreatment, plasma treatment and graphene oxide reaction. Acetone pretreatment is used to remove oil and impurities from the fiber surface, plasma treatment is used to introduce surface active groups and increase roughness, and graphene oxide reaction is used to construct interfacial binding sites.

[0009] The modification process of the modified rubber particles is as follows: the rubber particles are soaked in sodium hydroxide and then filtered to obtain the modified rubber particles; the modification method of the rubber particles is: chemical etching modification with sodium hydroxide solution, which removes the surface inert layer and introduces polar groups such as hydroxyl and carboxyl groups by etching the surface of the rubber particles with alkaline solution.

[0010] (3) The steps for synergistic reinforcement of silicate cement with modified basalt fiber and modified rubber particles are as follows: 1) Weigh the modified rubber particles and silicate cement according to the proportion, put them into a twin-shaft mixer and mix them evenly to obtain a mixture for later use; after adding silicate cement, control the mixing speed to 200 rpm, the mixing time to 1~5 min, the mixing environment temperature to 25~35℃, the relative humidity to 40~60%, and the dispersion uniformity of the modified rubber particles in the cement matrix to ≥90%.

[0011] 2) Weigh the modified basalt fiber according to the ratio, add it together with the reaction liquid of the heating reaction to the mixture prepared in step 1), then add water and water-reducing agent, and stir evenly to obtain the mixture; wherein, the amount of water added is 20~30% of the mass of silicate cement, and the amount of water-reducing agent added is 0.1~0.5% of the mass of silicate cement.

[0012] The method for preparing modified and reinforced silicate cement using basalt fiber and rubber particles includes the following parameters for plasma treatment of the basalt fiber: treatment time 5-30 min, radio frequency power 50-200 W, and nitrogen flow rate 20-60 sccm. The plasma-treated basalt fiber is then added to a graphene oxide solution with a concentration of 0.05-0.2 g / L and ultrasonically dispersed for 30-120 min using an ultrasonic machine with an ultrasonic power of 100-300 W and an ultrasonic frequency of 20-60 kHz. Urea is then added, and the mixture is heated to react at a reaction temperature of 40-80℃ and a stirring speed of 100-300 rpm for 1-2 h. After the reaction, the mixture is filtered and dried to obtain the modified basalt fiber. The mass ratio of urea to graphene oxide is 1-3:1.

[0013] The method for preparing basalt fiber and rubber particle modified reinforced silicate cement includes the following modification parameters: the rubber particles are modified with a 5-15% sodium hydroxide solution, soaked for 2-4 hours, and stirred every 30-60 minutes during the soaking process; after soaking, the particles are rinsed with deionized water until the pH value is 6.5-7.5, filtered, and dried at 80-100℃ for 2-3 hours.

[0014] In the method for preparing basalt fiber and rubber particle modified reinforced silicate cement, in step 1), silicate cement is added and stirred evenly, preferably at a stirring temperature of 25±5℃.

[0015] In the method for preparing basalt fiber and rubber particle modified reinforced silicate cement, in step 2), after adding the mixture, the mixture is first stirred at 100 rpm for 1-3 minutes to initially mix the modified basalt fiber with the mixture; then the speed is increased to 300-500 rpm and stirred for 2-5 minutes until the cement paste exhibits a uniform flow state and there is no obvious fiber agglomeration. The method for preparing basalt fiber and rubber particle modified reinforced silicate cement, wherein the water-reducing agent in step 2) is a polycarboxylate-based high-efficiency water-reducing agent with a solid content ≥40%, a water reduction rate ≥25%, and a compatibility grade of A with cement.

[0016] The aforementioned basalt fiber and rubber particle modified reinforced silicate cement and its preparation method, wherein when the amount of modified basalt fiber added is 0.1 parts, the flexural strength of the cement is increased by 30% compared with the control group, suitable for building walls and floors; when the amount of modified rubber particles added is 8 parts, the impact strength of the cement is increased by 60% compared with the control group, suitable for airport pavements, parking lots, and cargo stations that are prone to impact; when the plasma treatment time is adjusted to 30 min and the radio frequency power is 200W, the interfacial bonding strength of basalt fiber is increased to 80%.

[0017] The advantages and effects of this invention are: This invention modifies basalt fibers to increase their surface roughness, thereby enhancing their bond strength with the cement matrix. Furthermore, hydrophilic groups and grafted graphene oxide are introduced onto the surface to further strengthen the interfacial bond between the basalt fibers and the cement matrix. Simultaneously, modification of the rubber particles enhances their surface hydrophilicity, further strengthening the bond between the rubber particles and the cement matrix. This synergistic effect strengthens silicate cement, making it suitable for engineering applications requiring high mechanical properties and durability of cement-based materials, such as road and bridge construction, airport pavement, and tunnel lining. Attached Figure Description

[0018] Figure 1 Image of unprocessed basalt fibers; Figure 2 Image of modified basalt fiber. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings.

[0020] The present invention discloses a modified basalt fiber and modified rubber particle synergistic reinforced silicate cement, which, by mass fraction, comprises 0.1 to 1 part of modified basalt fiber, 1 to 8 parts of modified rubber particles, and 70 to 100 parts of silicate cement.

[0021] The modified basalt fibers are 6-12 mm in length and 15-25 μm in diameter. This length prevents agglomeration in cement, allowing for uniform dispersion within the cement matrix, effectively bridging micro-cracks and enhancing the crack resistance of silicate cement.

[0022] This invention treats the surface of basalt fiber and rubber. The modification process of basalt fiber is as follows: basalt fiber is pretreated with acetone and dried for later use. The pretreated basalt fiber is then modified with plasma and graphene oxide to obtain the final product. The mass ratio of graphene oxide to basalt fiber is 1-5:100. Specifically, the basalt fiber is immersed in a 60-80% acetone solution for 3-9 hours, then drained and recovered, washed with deionized water to remove excess acetone, and dried for later use. 2g of the pretreated basalt fiber is then treated with plasma for 20 minutes, at a radio frequency power of 100W, and a nitrogen flow rate of 240 sccm to obtain plasma-treated basalt fiber.

[0023] Plasma-treated basalt fibers were added to a 0.08 g / L graphene oxide solution and ultrasonically dispersed for 30–120 min in an ultrasonic machine with an ultrasonic power of 100–300 W and an ultrasonic frequency of 20–60 kHz. Subsequently, 0.8–1.2 g of urea was added, and the mixture was heated to react at a reaction temperature of 40–80 °C and a stirring speed of 100–300 rpm for 1–2 h. After the reaction, the fibers were filtered and dried to obtain modified basalt fibers. Scanning electron microscopy revealed that spots appeared on the fiber surface after plasma treatment, and the fiber surface became rougher. Further grafting with graphene oxide resulted in graphene oxide adhering to the surface, making the fibers even rougher and increasing their specific surface area.

[0024] The modification process of rubber granules is as follows: Rubber granules are pretreated with sodium hydroxide, filtered, washed, and dried. Specifically, 2-5g of rubber granules are soaked in 5-25mL of a 5-15% sodium hydroxide solution for 2-4 hours, stirring every 30-60 minutes during soaking. After soaking, the granules are rinsed with deionized water until the pH reaches 6.5-7.5, filtered, and dried at 80-100℃ for 2-3 hours to obtain the modified rubber granules. The modified rubber granules change from hydrophobic to hydrophilic on the surface, enhancing the bond strength between rubber and cement, and thus improving the strength and toughness of silicate cement.

[0025] The steps for preparing the above-mentioned modified basalt fiber and modified rubber particle synergistic reinforced silicate cement are as follows: (1) Weigh the modified rubber particles and silicate cement according to the proportion, put them into a twin-shaft mixer and mix them evenly to obtain a mixture for later use; among them, after adding silicate cement, control the stirring speed to 200 rpm, the stirring time to 1~5 min, the stirring environment temperature to 25~35℃ and the relative humidity to 40~60%, to ensure that the modified rubber particles are dispersed evenly in the cement matrix ≥90%.

[0026] (2) Weigh the modified basalt fiber according to the proportion, add it together with the reaction liquid of the heating reaction to the mixture prepared in step (1), then add water and water-reducing agent, and stir evenly to obtain the mixture; wherein, the amount of water added is 20~30% of the mass of silicate cement, and the amount of water-reducing agent added is 0.1~0.5% of the mass of silicate cement; wherein, after adding the mixture, stir at 100 rpm for 1~3 min to allow the modified basalt fiber to be initially mixed with the mixture; then increase the speed to 300~500 rpm and stir for 2~5 min until the cement paste is in a uniform flow state and there is no obvious fiber agglomeration; the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent with a solid content ≥40%, a water reduction rate ≥25%, and a compatibility grade with cement of A grade.

[0027] Specific embodiments are provided below with reference to the accompanying drawings and parameters: I. Preparation of Modified Basalt Fiber 1. Acetone pretreatment: Take 100g of basalt fiber with a length of 8mm and a diameter of 20μm, soak it in 2000mL of acetone solution at a solid-liquid ratio of 1:20 (g / mL) for 45min, stirring once every 20min; after soaking, rinse 4 times with deionized water until pH=7.0, and dry in a 90℃ forced-air drying oven for 2.5h; 2. Plasma treatment: Place the pretreated fibers into a vacuum plasma treatment instrument (vacuum degree 5Pa), introduce nitrogen gas with a purity of 99.99% (flow rate 40sccm), adjust the radio frequency power to 100W, and treat for 15 minutes; remove after natural cooling to room temperature; 3. Graphene oxide reaction: Prepare 5000 mL of 0.1 g / L graphene oxide solution, add the treated fiber, and ultrasonically disperse at 200 W and 40 kHz for 60 min; add 0.5 g of urea (mass ratio of 2:1 to graphene oxide), and heat at 60 °C and 200 rpm for 1.5 h; filter and dry in a 90 °C oven for 2.5 h to obtain modified basalt fiber.

[0028] II. Preparation of Modified Rubber Particles 1. Raw material pretreatment: Select 80g of waste tire rubber granules with a particle size of 1.0mm (deviation ≤0.3mm) and blow off the surface dust with compressed air; 2. Alkaline soaking: Place the rubber granules into 1600mL of 10% sodium hydroxide solution at a solid-liquid ratio of 1:20 (g / mL) and soak at room temperature (25℃) for 3 hours, stirring at 80rpm every 45 minutes. 3. Post-treatment: Rinse the rubber particles with deionized water until pH=7.0, vacuum filter, and dry in a 90℃ forced-air drying oven for 2.5h to obtain modified rubber particles.

[0029] III. Preparation of Synergistically Reinforced Silicate Cement 1. Mixture preparation: Weigh 5 parts of the modified rubber particles from Example 2 and 90 parts of PO42.5 grade silicate cement (28-day compressive strength 45 MPa, initial setting time 50 min, final setting time 550 min) according to the mass fraction, and place them in a twin-shaft mixer; control the stirring speed at 200 rpm, ambient temperature at 30℃, and relative humidity at 50%, and stir for 3 min; microscopic observation shows that the rubber particle dispersion uniformity is 92%; 2. Cement slurry preparation: Weigh 0.5 parts of the modified basalt fiber from Example 1 and add it to the mixture along with 500 mL of graphene oxide reaction clarifying liquid; add 22.5 parts of deionized water (25% of cement mass) and 0.27 parts of polycarboxylate superplasticizer (0.3% of cement mass, solid content 40%, water reduction rate 28%, compatibility grade A); stir at 100 rpm for 2 min, then stir at 400 rpm for 4 min, and measure the slurry fluidity to be 190 mm, which is the finished product.

[0030] IV. Performance Testing The finished product was prepared into 40mm×40mm×160mm test blocks according to GB / T17671-1999 "Test Method for Strength of Cement Mortar". After curing under standard curing conditions (temperature 20±2℃, relative humidity ≥95%) for 28 days, the mechanical properties and durability were tested. Unmodified PO42.5 grade cement was used as the control group. The results are shown in the table below: Group 28-day compressive strength (MPa) 28-day flexural strength (MPa) Impact resistance (kJ / m²) Strength loss rate (%) after 200 freeze-thaw cycles Finished product 58.2 8.5 13.2 6.5 control group 55.1 6.2 8.3 12.8 The results show that the mechanical properties and durability of the finished product of this invention are significantly better than those of ordinary cement, verifying the effectiveness of this invention.

[0031] The scope of protection of this invention is defined by the claims and is not limited to the above embodiments: when the amount of modified basalt fiber added is 0.1 parts, the 28-day flexural strength of cement is increased by 30% compared with the control group, which is suitable for ordinary building walls, floors, and other scenarios; when the amount of modified rubber particles added is 8 parts, the impact strength of cement is increased by 60% compared with the control group, which is suitable for impact-prone scenarios such as airport pavements, parking lots, and cargo stations; when the plasma treatment time is adjusted to 30 minutes and the radio frequency power is 200W, the interfacial bonding strength of basalt fiber can be increased by 80%, but the processing efficiency needs to be balanced according to the engineering cost budget. Adjustments to modification parameters and component dosages, as long as they fall within the scope defined by the claims, are within the scope of protection of this invention.

Claims

1. A basalt fiber and rubber particle modified reinforced silicate cement, characterized in that, The cement, by mass fraction, comprises 0.1 to 1 part modified basalt fiber, 1 to 8 parts modified rubber particles, and 70 to 100 parts silicate cement; The rubber particles have a particle size of 0.5~2.0mm and a particle size deviation of ≤0.3mm; the silicate cement is PO 42.5 grade general-purpose silicate cement, which conforms to GB 175-2007 "General-purpose Silicate Cement" standard, with a 28-day compressive strength ≥42.5MPa, an initial setting time ≥45min, and a final setting time ≤600min; the modified rubber particles have a dispersion uniformity of ≥90% in the cement matrix; the modified basalt fibers have a length of 6~12mm and a diameter of 15~25μm.

2. A method for preparing basalt fiber and rubber particle modified reinforced silicate cement, characterized in that, The preparation process described above is as follows: The modification process of modified basalt fiber is as follows: basalt fiber is pretreated with acetone, dried and set aside for later use. The pretreated basalt fiber is then treated with plasma and reacted with graphene oxide. The modification method of the modified basalt fiber is a three-stage composite modification of acetone pretreatment, plasma treatment and graphene oxide reaction. The acetone pretreatment is used to remove oil and impurities from the fiber surface, the plasma treatment is used to introduce surface active groups and increase roughness, and the graphene oxide reaction is used to construct interfacial binding sites. The modification process of the modified rubber particles is as follows: after soaking the rubber particles in sodium hydroxide, the modified rubber particles are obtained by filtration; the modification method of the rubber particles is: chemical etching modification with sodium hydroxide solution, which removes the surface inert layer and introduces polar groups such as hydroxyl and carboxyl groups by etching the surface of the rubber particles with alkaline solution. (3) The steps for synergistic reinforcement of silicate cement with modified basalt fiber and modified rubber particles are as follows: 1) Weigh the modified rubber granules and silicate cement according to the proportion, put them into a twin-shaft mixer and mix them evenly to obtain a mixture for later use; after adding silicate cement, control the mixing speed at 200 rpm, the mixing time at 1~5 min, the mixing environment temperature at 25~35℃ and the relative humidity at 40~60%, and the dispersion uniformity of the modified rubber granules in the cement matrix ≥90%; 2) Weigh the modified basalt fiber according to the ratio, add it together with the reaction liquid of the heating reaction to the mixture prepared in step 1), then add water and water-reducing agent, and stir evenly to obtain the mixture; wherein, the amount of water added is 20~30% of the mass of silicate cement, and the amount of water-reducing agent added is 0.1~0.5% of the mass of silicate cement.

3. The method for preparing basalt fiber and rubber particle modified reinforced silicate cement according to claim 2, characterized in that, The parameters for plasma treatment of the basalt fiber are as follows: treatment time 5-30 min, radio frequency power 50-200 W, and nitrogen flow rate 20-60 sccm. The plasma-treated basalt fiber is added to a graphene oxide solution with a concentration of 0.05-0.2 g / L and ultrasonically dispersed in an ultrasonic machine with an ultrasonic power of 100-300 W and an ultrasonic frequency of 20-60 kHz for 30-120 min. Then, urea is added and the mixture is heated to react for 1-2 h at a reaction temperature of 40-80℃ and a stirring speed of 100-300 rpm. After the reaction, the mixture is filtered and dried to obtain the modified basalt fiber. The mass ratio of urea to graphene oxide is 1-3:

1.

4. The method for preparing basalt fiber and rubber particle modified reinforced silicate cement according to claim 2, characterized in that, The modification parameters of the rubber particles are as follows: a 5-15% sodium hydroxide solution is used for soaking for 2-4 hours, with stirring every 30-60 minutes during the soaking process; after soaking, the particles are rinsed with deionized water until the pH value is 6.5-7.5, filtered, and dried at 80-100℃ for 2-3 hours.

5. The method for preparing basalt fiber and rubber particle modified reinforced silicate cement according to claim 2, characterized in that, In step 1), silicate cement is added and stirred evenly, preferably at a stirring temperature of 25±5℃.

6. The method for preparing basalt fiber and rubber particle modified reinforced silicate cement according to claim 2, characterized in that, In step 2), after adding the mixture, stir at 100 rpm for 1 to 3 minutes to initially mix the modified basalt fiber with the mixture; then increase the speed to 300 to 500 rpm and stir for 2 to 5 minutes until the cement paste is in a uniform flow state and there is no obvious fiber agglomeration.

7. The method for preparing basalt fiber and rubber particle modified reinforced silicate cement according to claim 2, characterized in that, The water-reducing agent in step 2) is a polycarboxylate-based high-efficiency water-reducing agent with a solid content ≥40%, a water reduction rate ≥25%, and a compatibility grade of A with cement.

8. The basalt fiber and rubber particle modified reinforced silicate cement and its preparation method according to claim 1 or 2, characterized in that, When the amount of modified basalt fiber added is 0.1 parts, the flexural strength of cement is increased by 30% compared with the control group, which is suitable for building walls and floors; when the amount of modified rubber particles added is 8 parts, the impact strength of cement is increased by 60% compared with the control group, which is suitable for airport pavement, parking lot and cargo station, which are prone to impact; when the plasma treatment time is adjusted to 30 min and the radio frequency power is 200W, the interfacial bonding strength of basalt fiber is increased to 80%.

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