Early-strength grinding aid as well as preparation method and application thereof

Abstract

The invention discloses an early-strength grinding aid as well as a preparation method and application thereof, and belongs to the technical field of building materials. Every 100 parts of the early strength grinding aid comprises the following components in parts by weight: 12-18 parts of dual modified nano calcium silicate, 8-12 parts of a citric acid modified alcohol amine compound, 18-22 parts of alkali activated superfine slag powder, 3-6 parts of a dispersing agent, 2-4 parts of a stabilizer and the balance of water, the double modified nano calcium silicate is prepared by reacting sodium silicate with calcium nitrate and performing double modification through polyvinylpyrrolidone and a silane coupling agent; the citric acid modified alcohol amine compound is a citric acid modified alcohol amine compound, and the alcohol amine compound comprises triethanolamine and diethyl isopropanolamine; the alkali activated superfine slag powder is slag powder activated by NaOH. The early-strength grinding aid is low in cost, can effectively improve the 3d strength of mineral powder cement after being doped in the mineral powder cement, and enables the mineral powder cement to be free of shrinkage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to an early strength grinding aid, a preparation method and application thereof. BACKGROUND

[0002] In cement production, in order to reduce costs and improve environmental protection, the content of slag powder (mineral powder) is often increased to 20%~40%, but this leads to slow early hydration and insufficient 3d strength (usually <15MPa), affecting construction. The existing technology generally uses the way of adding early strength agent to improve it, but the existing early strength agent preparation process is complex, the cost is high, and it is easy to agglomerate and has poor stability, which can easily lead to insufficient early strength of cement containing more than 20wt% of mineral powder, and late strength appears to be reversed.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] The present application aims to provide an early strength grinding aid, a preparation method and application thereof, to solve or improve the above technical problems.

[0005] The present application can be achieved as follows: In a first aspect, the present application provides an early strength grinding aid, wherein, per 100 parts of the early strength grinding aid, 12 parts~18 parts of double modified nano calcium silicate, 8 parts~12 parts of citric acid modified alcohol amine complex, 18 parts~22 parts of alkali activated slag powder, 3 parts~6 parts of dispersant and 2 parts~4 parts of stabilizer are included, and the balance is water. The double modified nano calcium silicate is obtained by reacting sodium silicate and calcium nitrate, and is double modified by polyvinylpyrrolidone and silane coupling agent. The citric acid modified alcohol amine complex is an alcohol amine complex modified by citric acid, wherein the alcohol amine complex includes triethanolamine and diethyl monoisopropylol amine. The alkali activated slag powder is a slag powder activated by NaOH.

[0006] In an optional embodiment, the particle size of the double modified nano calcium silicate is 60nm~150nm.

[0007] In an optional embodiment, the preparation method of the double modified nano calcium silicate includes mixing a sodium silicate solution, a calcium nitrate solution and a surfactant, and then adding polyvinylpyrrolidone and a silane coupling agent, and ultrasonic dispersion.

[0008] In an optional embodiment, the volume ratio of the sodium silicate solution to the calcium nitrate solution is 1.15:1 to 2:1; wherein the concentration of the sodium silicate solution is 12wt%~18wt%, and the concentration of the calcium nitrate solution is 8wt%~12wt%.

[0009] In an optional embodiment, the mass of the surfactant is 0.8wt% to 1.2wt% of the total mass of the sodium silicate solution and the calcium nitrate solution.

[0010] In an optional embodiment, the sodium silicate solution, calcium nitrate solution, and surfactant are mixed at a pH of 10-11 for 1-3 hours.

[0011] In an optional embodiment, the mass of polyvinylpyrrolidone is 1.5wt% to 2.5wt% of the total mass of sodium silicate solution and calcium nitrate solution.

[0012] In an optional embodiment, the mass of the silane coupling agent is 0.5wt% to 1.5wt% of the total mass of the sodium silicate solution and the calcium nitrate solution.

[0013] In an optional embodiment, ultrasonic dispersion is performed at 250W~350W for 40min~50min.

[0014] In an optional embodiment, the alcoholamine complex comprises triethanolamine and diethylmonoisopropanolamine in a mass ratio of 1.2:1 to 1.8:1.

[0015] In an optional embodiment, the amount of citric acid used is 2wt% to 5wt% of the alcoholamine complex.

[0016] In an optional embodiment, the particle size of the alkali-activated slag powder is 2μm~8μm, and the specific surface area is 450m². 2 / kg~550m 2 / kg.

[0017] In an optional embodiment, the slag powder includes S95 ore powder.

[0018] In an optional embodiment, the amount of NaOH used is 5wt% to 8wt% of the slag powder.

[0019] In an optional embodiment, the preparation of alkali-activated slag powder includes: mixing slag powder with NaOH solution at a pH of 12-13 for 2-4 hours.

[0020] In an optional embodiment, the concentration of the NaOH solution is 5wt% to 7wt%.

[0021] In an optional embodiment, the dispersant includes at least one of polycarboxylate and sodium polyacrylate.

[0022] In an optional embodiment, the dispersant comprises a polycarboxylate and sodium polyacrylate in a mass ratio of (0.8~1.2):(0.8~1.2).

[0023] In an optional implementation, the stabilizer includes hydroxypropyl methylcellulose.

[0024] In a second aspect, the present invention provides a method for preparing an early-strength grinding aid as described in any of the foregoing embodiments, comprising the following steps: mixing double-modified nano-calcium silicate, citric acid-modified alkanolamine complex, alkali-activated slag powder, dispersant, stabilizer and water according to a preset ratio.

[0025] Thirdly, the present invention provides a mineral powder cement, wherein the mineral powder cement is doped with the aforementioned early-strength grinding aid.

[0026] In an optional embodiment, the doping amount of the early strength grinding aid is 0.1wt% to 0.15wt%.

[0027] In an optional embodiment, the mineral powder content in the mineral powder cement is 20wt%~40wt%.

[0028] The beneficial effects of this invention include: The early-strength grinding aid provided by this invention utilizes dual-modified nano-calcium silicate as a nucleation inducing agent, citric acid-modified alkanolamine as an early-strength accelerator, and alkali-activated slag powder as a mineral powder activator to achieve accelerated early hydration of high-mineral-powder cement systems. Dispersants and stabilizers ensure more thorough and uniform mixing of the dual-modified nano-calcium silicate, citric acid-modified alkanolamine composite, and alkali-activated slag powder, resulting in a more stable system.

[0029] This early-strength grinding aid is low in cost and easy to prepare. It can improve the stability of mineral powder cement under low doping conditions, and enable cement with high mineral powder content to have better 3d compressive strength and 28d compressive strength, and no shrinkage phenomenon after 28d. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a physical image of the early-strength grinding aid prepared in Example 1. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0033] The early strength grinding aid provided by this invention, its preparation method, and its application are described in detail below.

[0034] This invention provides an early-strength grinding aid, which, by weight, comprises 12 to 18 parts of double-modified nano-calcium silicate, 8 to 12 parts of citric acid-modified alkanolamine complex, 18 to 22 parts of alkali-activated slag powder, 3 to 6 parts of dispersant, and 2 to 4 parts of stabilizer, with the balance being water.

[0035] This early-strength grinding aid utilizes dual-modified nano-calcium silicate as a nucleation inducing agent, citric acid-modified alkanolamine as an early-strength accelerator, and alkali-activated slag powder as a mineral powder activator to accelerate the early hydration of high-mineral-powder cement systems. Dispersants and stabilizers ensure more thorough and uniform mixing of the dual-modified nano-calcium silicate, citric acid-modified alkanolamine composite, and alkali-activated slag powder, resulting in a more stable system.

[0036] In some optional embodiments, the amount of dual-modified nano-calcium silicate in every 100 parts of early-strength grinding aid can be 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, or 18 parts, or other values ​​within the range of 12 to 18 parts. If the amount of dual-modified nano-calcium silicate is too small, it will not provide enough nucleation sites, resulting in insufficient early-strength effect; if the amount of dual-modified nano-calcium silicate is too large, it will easily lead to an increase in system viscosity, difficulty in dispersion, and affect the fluidity and uniformity of cement.

[0037] The amount of citric acid-modified alkanolamine complex in every 100 parts of early-strength grinding aid can be 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, or 12 parts, or other values ​​within the range of 8 to 12 parts. If the amount of citric acid-modified alkanolamine complex is too small, it will not be conducive to the complexation of Ca. 2+ It promotes the early hydration reaction of cement, which leads to a weakening of the early strength effect; if too much citric acid modified amine compound is used, it can easily lead to excessively rapid setting or hinder the development of strength in the later stage, and will also increase costs.

[0038] The amount of alkali-activated slag powder in every 100 parts of early-strength grinding aid can be 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, 20.5 parts, 21 parts, 21.5 parts, or 22 parts, or other values ​​within the range of 18 parts to 22 parts.

[0039] If the amount of alkali-activated slag powder is too small, it will not be conducive to fully activating the glassy phase in the slag powder, resulting in slow hydration reaction and insufficient early strength; if the amount of alkali-activated slag powder is too large, it will easily lead to excessive alkalinity of the system, triggering alkali-aggregate reaction or increasing the risk of corrosion.

[0040] The amount of dispersant in every 100 parts of early strength grinding aid can be 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, or 6 parts, or other values ​​within the range of 3 to 6 parts.

[0041] The amount of stabilizer in every 100 parts of early strength grinding aid can be 2 parts, 2.5 parts, 3 parts, 3.5 parts or 4 parts, or other values ​​within the range of 2 to 4 parts.

[0042] The following is a description of each ingredient.

[0043] Dual-modified calcium silicate nanoparticles In this invention, the dual-modified nano-calcium silicate is obtained by reacting sodium silicate and calcium nitrate, and then undergoing dual modification with polyvinylpyrrolidone (PVP) and a silane coupling agent, which can improve the affinity between nano-calcium silicate and mineral powder. The modification mechanism of PPV is that it adsorbs onto the surface of nano-calcium silicate through steric hindrance, preventing particle agglomeration and improving dispersibility and stability. The modification mechanism of the silane coupling agent is that the silane end hydrolyzes to form Si-OH, which reacts with the hydroxyl groups on the surface of nano-calcium silicate to form covalent bonds, while the epoxy end reacts with the active groups in the mineral powder or cement matrix, improving interfacial compatibility and affinity. The dual-modified nano-calcium silicate (zeta potential approximately -20mV to -30mV) can further induce tricalcium silicate hydration to generate cementitious products.

[0044] In some alternative embodiments, the preparation method of dual-modified nano-calcium silicate may include: mixing sodium silicate solution with calcium nitrate solution and surfactant, followed by adding polyvinylpyrrolidone and silane coupling agent, and ultrasonically dispersing.

[0045] The volume ratio of sodium silicate solution to calcium nitrate solution can be from 1.15:1 to 2:1, such as 1.15:1, 1.5:1 or 2:1, or other values ​​within the range of 1.15:1 to 2:1.

[0046] The concentration of sodium silicate solution can be 12wt% to 18wt%, such as 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, or 18wt%, or other values ​​within the range of 12wt% to 18wt%.

[0047] The concentration of calcium nitrate solution can be 8wt% to 12wt%, such as 8wt%, 9wt%, 10wt%, 11wt% or 12wt%, or other values ​​within the range of 8wt% to 12wt%.

[0048] The mass of the surfactant can be 0.8wt% to 1.2wt% of the total mass of the sodium silicate solution and calcium nitrate solution, such as 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, or 1.2wt%, or other values ​​within the range of 0.8wt% to 1.2wt%.

[0049] The above-mentioned sodium silicate solution, calcium nitrate solution and surfactant can be mixed at a pH of 10-11 (e.g., 10, 10.2, 10.5, 10.8 or 11) for 1-3 hours (e.g., 1 hour, 2 hours or 3 hours).

[0050] In some optional embodiments, the mass of polyvinylpyrrolidone can be 1.5wt% to 2.5wt% of the total mass of sodium silicate solution and calcium nitrate solution, such as 1.5wt%, 1.8wt%, 2wt%, 2.2wt%, or 2.5wt%, or other values ​​within the range of 1.5wt% to 2.5wt%. If the amount of polyvinylpyrrolidone is too small, it will not effectively prevent the agglomeration of nano-calcium silicate particles, leading to reduced stability; if the amount of polyvinylpyrrolidone is too large, it may reduce the nucleation activity or affect the flowability of the system, and will also increase the cost.

[0051] The mass of the silane coupling agent can be 0.5wt% to 1.5wt% of the total mass of the sodium silicate solution and calcium nitrate solution, such as 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, or 1.5wt%, or other values ​​within the range of 0.5wt% to 1.5wt%. If the amount of silane coupling agent is too small, it will not be conducive to sufficient modification of the nano-calcium silicate surface, resulting in insufficient affinity with the mineral powder; if the amount of silane coupling agent is too large, it will not be conducive to avoiding self-polymerization reactions, which may reduce modification efficiency and increase costs. For example, the silane coupling agent mentioned above can be KH-560.

[0052] After adding polyvinylpyrrolidone and silane coupling agent, ultrasonic dispersion can be carried out at 250W~350W (such as 250W, 280W, 300W, 320W or 350W, etc.) for 40min~50min (such as 40min, 45min or 50min, etc.).

[0053] In some optional embodiments, the particle size of the dual-modified nano-calcium silicate can be 60nm~150nm, such as 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm or 150nm, or other values ​​in the range of 60nm~150nm.

[0054] If the particle size of the double-modified nano-calcium silicate is too small, it will be detrimental to the stability of the system and will easily lead to agglomeration and uneven dispersion; if the particle size of the double-modified nano-calcium silicate is too large, it will be detrimental to providing sufficient specific surface area and crystal nucleation sites, resulting in a weakening of the early strength effect.

[0055] Citric acid-modified alcohol amine complex In this invention, the citric acid-modified alkanolamine complex is a citric acid-modified alkanolamine complex, wherein the alkanolamine complex includes triethanolamine and diethylmonoisopropanolamine. This citric acid-modified alkanolamine complex has a positive effect on Ca... 2+ It has a strong low-temperature complexing ability, which is beneficial for promoting the reaction. In some alternative embodiments, the alkanolamine complex comprises triethanolamine and diethylmonoisopropanolamine in a mass ratio of 1.2:1 to 1.8:1. In some more preferred embodiments, the alkanolamine complex comprises triethanolamine and diethylmonoisopropanolamine in a mass ratio of 1.5:1.

[0056] This invention specifically employs a combination of triethanolamine and diethylene monoisopropanolamine because diethylene monoisopropanolamine primarily promotes the hydration reaction of C3S. The combination of the two can comprehensively accelerate the early mineral hydration of cement, improve early strength, and enhance low-temperature adaptability. Using only triethanolamine or diethylene monoisopropanolamine would not adequately promote the hydration of different cement minerals, leading to an uneven early strength effect. Furthermore, both insufficient and excessive amounts of triethanolamine in the amine complex will result in a deterioration in its effectiveness.

[0057] In some alternative embodiments, the amount of citric acid can be 2wt% to 5wt% of the alkanolamine complex, such as 2wt%, 3wt%, 4wt% or 5wt%, or other values ​​within the range of 2wt% to 5wt%.

[0058] In some optional embodiments, the citric acid-modified alkanolamine complex can be prepared as follows: triethanolamine and diethylisopropanolamine are mixed at a mass ratio of 1.5:1, and citric acid is added at 2wt% to 5wt% of the total mass of the alkanolamine complex. The mixture is stirred at 50°C to 70°C for 2 to 4 hours, and then cooled to room temperature to obtain the citric acid-modified alkanolamine complex. This modification process can enhance the alkanolamine's affinity for Ca. 2+ It enhances the complexing ability and improves the early strength effect at low temperatures.

[0059] Alkali-activated ground granulated blast furnace slag In this invention, the alkali-activated slag powder is slag powder activated with NaOH. The alkali-activated slag powder can increase the glass solubility, making it >30%, and can also reduce the porosity of cement, without Cl and S corrosion, thus improving the 3-day strength of cement and mitigating its 28-day shrinkage.

[0060] In some optional embodiments, the particle size of the alkali-activated slag powder can be 2μm to 8μm, such as 2μm, 3μm, 4μm, 5μm, 6μm, 7μm or 8μm, or other values ​​within the range of 2μm to 8μm.

[0061] In some optional embodiments, the specific surface area of ​​alkali-activated slag powder can be 450 m². 2 / kg~550m 2 / kg, such as 450m 2 / kg, 480m 2 / kg, 500m 2 / kg, 520m 2 / kg or 550m 2 / kg, etc., can also be 450m 2 / kg~550m 2 Other values ​​within the / kg range.

[0062] By using alkali-activated slag micronized powder with the above-mentioned particle size and specific surface area, more active sites can be provided, promoting the dissolution and hydration reaction of the mineral powder glass, filling the pores of the cement matrix, and improving the density and overall strength.

[0063] In some optional embodiments, the preparation of alkali-activated slag powder may include mixing slag powder with NaOH solution at a pH of 12-13 (e.g., 12, 12.5 or 13) for 2-4 hours (e.g., 2 hours, 3 hours or 4 hours).

[0064] The concentration of the NaOH solution can be 5wt% to 7wt%, such as 5wt%, 6wt% or 7wt%, or other values ​​within the range of 5wt% to 7wt%.

[0065] Slag powder can include S95 ore powder, etc.

[0066] The amount of NaOH can be 5wt% to 8wt% of the slag powder, such as 5wt%, 6wt%, 7wt% or 8wt%, or other values ​​within the range of 5wt% to 8wt%.

[0067] Dispersant In this invention, the dispersant includes at least one of polycarboxylate and sodium polyacrylate.

[0068] In some alternative embodiments, the dispersant comprises a polycarboxylate and sodium polyacrylate in a mass ratio of (0.8~1.2):(0.8~1.2). In some preferred embodiments, the dispersant comprises a polycarboxylate and sodium polyacrylate in a mass ratio of 1:1.

[0069] Stabilizer In this invention, the stabilizer includes hydroxypropyl methylcellulose.

[0070] Accordingly, the present invention also provides a method for preparing the early strength grinding aid as described above, comprising the following steps: mixing double-modified nano-calcium silicate, citric acid modified alkanolamine complex, alkali-activated slag powder, dispersant, stabilizer and water according to a preset ratio.

[0071] Mixing is carried out under stirring and ultrasonic conditions. The ultrasonic dispersion time can be 25 min to 35 min, such as 25 min, 30 min or 35 min, or other values ​​within the range of 25 min to 35 min.

[0072] In addition, the present invention also provides a mineral powder cement, which is doped with the above-mentioned early strength grinding aid.

[0073] In some alternative embodiments, the doping amount of the early strength grinding aid can be 0.1wt% to 0.15wt%, such as 0.1wt%, 0.11wt%, 0.12wt%, 0.13wt%, 0.14wt%, or 0.15wt%, or other values ​​in the range of 0.1wt% to 0.15wt%.

[0074] In some alternative embodiments, the mineral powder content in the mineral powder cement can be 20wt% to 40wt%, such as 20wt%, 25wt%, 30wt%, 35wt% or 40wt%, or other values ​​within the range of 20wt% to 40wt%.

[0075] As mentioned above, the early-strength grinding aid provided by this invention can increase the 3d strength of mineral powder cement by more than 15% and reduce the cost by 12% to 18%.

[0076] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0077] Table 1. Composition of 1100 portions of early-strength grinding aid (parts)

[0078] Example 1 This embodiment provides an early-strength grinding aid (such as...) Figure 1 As shown in Table 1, by weight, every 100 parts of early-strength grinding aid includes 15 parts of double-modified nano-calcium silicate (particle size 100 nm), 10 parts of citric acid-modified alkanolamine complex, and 20 parts of alkali-activated slag micro powder (particle size 5 μm, specific surface area 500 m²). 2 / kg), 4 parts dispersant (polycarboxylate and sodium polyacrylate in a 1:1 mass ratio) and 3 parts stabilizer (hydroxypropyl methylcellulose), with the remainder being water.

[0079] The preparation method of this early strength grinding aid includes: mixing and stirring the double-modified nano calcium silicate, citric acid modified alkanolamine complex, alkali-activated slag powder, dispersant, stabilizer and water according to the above ratio, and then ultrasonically dispersing for 30 min.

[0080] The preparation method of the above-mentioned dual-modified nano-calcium silicate includes: mixing a 15wt% sodium silicate solution and a 10wt% calcium nitrate solution with a surfactant (sodium dodecylbenzenesulfonate) at pH 10.5 for 2 hours; then adding polyvinylpyrrolidone and a silane coupling agent (KH-560), and ultrasonically dispersing at 300W for 45 minutes; followed by filtration and drying of the solid. The volume ratio of sodium silicate solution to calcium nitrate solution is 1.5:1; the mass of the surfactant is 1wt% of the total mass of the sodium silicate and calcium nitrate solutions; the mass of polyvinylpyrrolidone is 2wt% of the total mass of the sodium silicate and calcium nitrate solutions; and the mass of the silane coupling agent is 1wt% of the total mass of the sodium silicate and calcium nitrate solutions.

[0081] The above-mentioned citric acid modified alkanolamine complex is a citric acid modified alkanolamine complex. The preparation method of the citric acid modified alkanolamine complex is as follows: triethanolamine and diethylisopropanolamine are mixed at a mass ratio of 1.5:1, citric acid accounting for 3.5 wt% of the total mass of the alkanolamine complex is added, the mixture is stirred and reacted at 60°C for 3 h, and then cooled to room temperature to obtain the citric acid modified alkanolamine complex.

[0082] The aforementioned alkali-activated slag powder is slag powder (S95 slag powder) activated with NaOH. The preparation of this alkali-activated slag powder includes: mixing slag powder with NaOH solution at a pH of 12.5 for 3 hours, followed by drying and pulverizing. The concentration of the NaOH solution is 6 wt%, and the amount of NaOH used is 6 wt% of the slag powder.

[0083] Examples 2~3 The early strength grinding aids provided in Examples 2 and 3 differ from those in Example 1 in that their component ratios are different, as shown in Table 1.

[0084] Example 4 This embodiment provides an early-strength grinding aid. The raw material ratio per 100 parts of the early-strength grinding aid is the same as in Example 1, except that: the particle size of the double-modified nano-calcium silicate is 60nm; the particle size of the alkali-activated slag powder is 2μm, and the specific surface area is 550m². 2 / kg; the dispersant is a mixture of polycarboxylate and sodium polyacrylate in a mass ratio of 1:1.2.

[0085] The preparation method of this early strength grinding aid includes: mixing and stirring the double-modified nano calcium silicate, citric acid modified alkanolamine complex, alkali-activated slag powder, dispersant, stabilizer and water according to the above ratio, and then ultrasonically dispersing for 35 minutes.

[0086] The preparation method of the above-mentioned dual-modified nano-calcium silicate includes: mixing a 12wt% sodium silicate solution and an 8wt% calcium nitrate solution with a surfactant (sodium dodecylbenzenesulfonate) at pH 10 for 3 hours; then adding polyvinylpyrrolidone and a silane coupling agent (KH-560), and ultrasonically dispersing at 250W for 50 minutes; followed by filtration and drying of the solid. The volume ratio of sodium silicate solution to calcium nitrate solution is 1.15:1; the mass of the surfactant is 0.8wt% of the total mass of the sodium silicate and calcium nitrate solutions; the mass of polyvinylpyrrolidone is 1.5wt% of the total mass of the sodium silicate and calcium nitrate solutions; and the mass of the silane coupling agent is 0.5wt% of the total mass of the sodium silicate and calcium nitrate solutions.

[0087] The above-mentioned citric acid modified alkanolamine complex is a citric acid modified alkanolamine complex, wherein the alkanolamine complex includes triethanolamine and diethylisopropanolamine in a mass ratio of 1.2:1, and the amount of citric acid used is 2 wt% of the alkanolamine complex.

[0088] The aforementioned alkali-activated slag powder is slag powder (S95 slag powder) activated with NaOH. The preparation of this alkali-activated slag powder includes: mixing slag powder with NaOH solution at pH 12 for 4 hours, followed by drying and pulverizing. The concentration of the NaOH solution is 5 wt%, and the amount of NaOH used is 8 wt% of the slag powder.

[0089] Example 5 This embodiment provides an early-strength grinding aid. The raw material ratio per 100 parts of the early-strength grinding aid is the same as in Example 1, except that: the particle size of the double-modified nano-calcium silicate is 150 nm; the particle size of the alkali-activated slag powder is 8 μm, and the specific surface area is 450 m². 2 / kg; the dispersant is a mixture of polycarboxylate and sodium polyacrylate in a mass ratio of 1:0.8.

[0090] The preparation method of this early strength grinding aid includes: mixing and stirring the double-modified nano calcium silicate, citric acid modified alkanolamine complex, alkali-activated slag powder, dispersant, stabilizer and water according to the above ratio, and then ultrasonically dispersing for 25 minutes.

[0091] The preparation method of the above-mentioned dual-modified nano-calcium silicate includes: mixing an 18wt% sodium silicate solution and a 12wt% calcium nitrate solution with a surfactant (sodium dodecylbenzenesulfonate) at pH 11 for 1 h; then adding polyvinylpyrrolidone and a silane coupling agent (KH-560), and ultrasonically dispersing at 350 W for 40 min; followed by filtration and drying of the solid. The volume ratio of sodium silicate solution to calcium nitrate solution is 2:1; the mass of the surfactant is 1.2wt% of the total mass of the sodium silicate and calcium nitrate solutions; the mass of the polyvinylpyrrolidone is 2.5wt% of the total mass of the sodium silicate and calcium nitrate solutions; and the mass of the silane coupling agent is 1.5wt% of the total mass of the sodium silicate and calcium nitrate solutions.

[0092] The above-mentioned citric acid modified alkanolamine complex is a citric acid modified alkanolamine complex, wherein the alkanolamine complex includes triethanolamine and diethylisopropanolamine in a mass ratio of 1.8:1, and the amount of citric acid used is 5 wt% of the alkanolamine complex.

[0093] The aforementioned alkali-activated slag powder is slag powder (S95 slag powder) activated with NaOH. The preparation of this alkali-activated slag powder includes: mixing slag powder with NaOH solution at pH 13 for 2 hours, followed by drying and pulverizing. The concentration of the NaOH solution is 7 wt%, and the amount of NaOH used is 5 wt% of the slag powder.

[0094] Comparative Examples 1~6 The early-strength grinding aids provided in Comparative Examples 1-6 differ from those in Example 1 in that their component ratios are different, as shown in Table 1.

[0095] Comparative Example 7 The difference between this comparative example and Example 1 is that the nano-calcium silicate is obtained by reacting sodium silicate and calcium nitrate, but it has not undergone dual modification with polyvinylpyrrolidone and silane coupling agent.

[0096] Comparative Example 8 The difference between this comparative example and Example 1 is that the nano-calcium silicate is obtained by reacting sodium silicate and calcium nitrate, but is only modified by polyvinylpyrrolidone.

[0097] Comparative Example 9 The difference between this comparative example and Example 1 is that the nano-calcium silicate is obtained by reacting sodium silicate and calcium nitrate, but is only modified by a silane coupling agent.

[0098] Comparative Example 10 The difference between this comparative example and Example 1 is that the citric acid-modified alkanolamine complex is replaced with a complex of unmodified triethanolamine and diethylmonoisopropanolamine.

[0099] Comparative Example 11 The difference between this comparative example and Example 1 is that the citric acid-modified alcohol amine complex is replaced with citric acid-modified triethanolamine.

[0100] Comparative Example 12 The difference between this comparative example and Example 1 is that the citric acid-modified alcohol amine complex is replaced with citric acid-modified diethylmonoisopropanolamine.

[0101] Comparative Example 13 The difference between this comparative example and Example 1 is that the alcohol amine complex includes triethanolamine and diethylmonoisopropanolamine in a mass ratio of 1:1.

[0102] Comparative Example 14 The difference between this comparative example and Example 1 is that the alcohol amine complex includes triethanolamine and diethylmonoisopropanolamine in a mass ratio of 1:1.5.

[0103] Comparative Example 15 The difference between this comparative example and Example 1 is that the alkali-activated slag powder is replaced with slag powder that has not been activated by NaOH.

[0104] Test case The early-strength grinding aids prepared in Examples 1-5 and Comparative Examples 1-15 were all added to cement containing 30 wt% mineral powder at a doping amount of 0.1 wt%. The performance of the corresponding mineral powder cements was compared, and the results are shown in Table 2. The 3-day compressive strength and 28-day compressive strength were determined according to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)". Stability was determined by observing whether precipitation occurred during the test period.

[0105] Table 2 Performance Results

[0106] As can be seen from Table 1, the early strength grinding aid provided in this embodiment of the invention, compared with the early strength grinding aid provided in the comparative example, can enable cement with high mineral powder content to have better 3d compressive strength and 28d compressive strength under the condition of lower doping amount, and no shrinkage phenomenon occurs after 28 days, indicating good stability of the mineral powder cement system.

[0107] In summary, the early-strength grinding aid provided by this invention has a low cost and is easy to prepare. This early-strength grinding aid can improve the stability of mineral powder cement under low doping conditions, and can enable cement with high mineral powder content to have better 3d compressive strength and 28d compressive strength, and no shrinkage phenomenon after 28d.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An early-strength grinding aid, characterized in that, By weight, every 100 parts of the early strength grinding aid comprises 12 to 18 parts of double-modified nano-calcium silicate, 8 to 12 parts of citric acid-modified alkanolamine complex, 18 to 22 parts of alkali-activated slag powder, 3 to 6 parts of dispersant, and 2 to 4 parts of stabilizer, with the balance being water. The dual-modified nano-calcium silicate is obtained by reacting sodium silicate and calcium nitrate, and then undergoing dual modification with polyvinylpyrrolidone and silane coupling agent. The citric acid-modified alkanolamine complex is a citric acid-modified alkanolamine complex, wherein the alkanolamine complex includes triethanolamine and diethylisopropanolamine; The alkali-activated slag powder is slag powder activated with NaOH.

2. The early-strength grinding aid according to claim 1, characterized in that, The particle size of the dual-modified nano-calcium silicate is 60nm~150nm.

3. The early-strength grinding aid according to claim 1 or 2, characterized in that, The preparation method of the dual-modified nano-calcium silicate includes: mixing sodium silicate solution with calcium nitrate solution and surfactant, then adding polyvinylpyrrolidone and silane coupling agent, and ultrasonically dispersing; Preferably, the volume ratio of the sodium silicate solution to the calcium nitrate solution is 1.15:1 to 2:1; wherein the concentration of the sodium silicate solution is 12wt% to 18wt%, and the concentration of the calcium nitrate solution is 8wt% to 12wt%. Preferably, the mass of the surfactant is 0.8 wt% to 1.2 wt% of the total mass of the sodium silicate solution and the calcium nitrate solution; Preferably, the sodium silicate solution, the calcium nitrate solution, and the surfactant are mixed at a pH of 10-11 for 1-3 hours. Preferably, the mass of the polyvinylpyrrolidone is 1.5 wt% to 2.5 wt% of the total mass of the sodium silicate solution and the calcium nitrate solution. Preferably, the mass of the silane coupling agent is 0.5wt% to 1.5wt% of the total mass of the sodium silicate solution and the calcium nitrate solution; Preferably, the ultrasonic dispersion is performed at 250W~350W for 40min~50min.

4. The early-strength grinding aid according to claim 1, characterized in that, The alcoholamine complex comprises triethanolamine and diethylmonoisopropanolamine in a mass ratio of 1.2:1 to 1.8:1; Preferably, the amount of citric acid used is 2wt% to 5wt% of the alcoholamine complex.

5. The early-strength grinding aid according to claim 1, characterized in that, The alkali-activated slag powder has a particle size of 2μm~8μm and a specific surface area of ​​450m². 2 / kg~550m 2 / kg; Preferably, the slag powder includes S95 ore powder; Preferably, the amount of NaOH used is 5wt% to 8wt% of the slag powder.

6. The early-strength grinding aid according to claim 5, characterized in that, The preparation of the alkali-activated slag powder includes: mixing slag powder with NaOH solution at a pH of 12-13 for 2-4 hours; Preferably, the concentration of the NaOH solution is 5wt% to 7wt%.

7. The early-strength grinding aid according to claim 1, characterized in that, The dispersant includes at least one of polycarboxylate and sodium polyacrylate; Preferably, the dispersant comprises a polycarboxylate and sodium polyacrylate in a mass ratio of (0.8~1.2):(0.8~1.2).

8. The early-strength grinding aid according to claim 1, characterized in that, The stabilizer includes hydroxypropyl methylcellulose.

9. A method for preparing an early-strength grinding aid as described in any one of claims 1 to 8, characterized in that, The process includes the following steps: mixing the dual-modified nano-calcium silicate, the citric acid-modified alkanolamine complex, the alkali-activated slag powder, the dispersant, the stabilizer, and water according to a preset ratio.

10. A mineral powder cement, characterized in that, The mineral powder cement is doped with the early strength grinding aid as described in any one of claims 1 to 8; Preferably, the doping amount of the early-strength grinding aid is 0.1wt%~0.15wt%; Preferably, the mineral powder content in the mineral powder cement is 20wt%~40wt%.

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