Anti-cracking cement mortar containing slag and preparation method thereof

Abstract

The application discloses a kind of containing slag anti-cracking cement mortar and preparation method thereof, it is related to slag cement mortar technical field, the anti-cracking cement mortar in the component ratio, by mass fraction including:100 portions of slag cement raw material, 39-44.5 portions of water 0.6-1 portion of polycarboxylic acid water reducing agent, 0.3-0.5 portions of superabsorbent polymer, 4-5 portions of activator, 0.03-0.05 portions of multi-walled carbon nanotube;Preparation method of anti-cracking cement mortar includes the following steps: slag cement raw material, superabsorbent polymer, multi-walled carbon nanotube is premixed 1-2min, water, polycarboxylic acid water reducing agent and activator are sequentially added, and low-speed mixing 1-2min, high-speed mixing 3-5min, obtain anti-cracking cement mortar.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of slag cement mortar, and particularly relates to a crack-resistant cement mortar containing slag and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the construction industry, traditional cement mortar gradually cannot meet the green environmental protection demand due to problems such as high energy consumption and high carbon emission. The production of ordinary Portland cement requires high-temperature calcination, which not only consumes a large amount of energy, but also is accompanied by significant greenhouse gas emission, which is contradictory to the current low-carbon economic development trend. As an important component of industrial waste slag, the active ingredient of slag can replace part of the cement clinker, improve the mechanical properties of the mortar, reduce the production cost, and reduce environmental pollution.

[0003] Research shows that the incorporation of slag can optimize the structure of cement stone, improve the material density, and effectively inhibit the generation of cracks. However, in the prior art, the synergistic mechanism between the slag content and the crack resistance of the mortar is not completely clear, and some products have problems such as insufficient early strength, high dry shrinkage rate, or unstable construction performance. In addition, key technical links such as slag particle size distribution control, activator compatibility, and production process parameter optimization still need to be broken through, which restricts the large-scale application of slag in crack-resistant mortar.

[0004] Under this background, it is of important practical significance to develop a slag-based crack-resistant cement mortar preparation technology with environmental protection and functionality, which can promote the transformation and upgrading of the building material industry and realize the green development of building engineering. SUMMARY

[0005] The present application relates to the technical field of slag cement mortar, and particularly relates to a crack-resistant cement mortar containing slag and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A crack-resistant cement mortar containing slag, the crack-resistant cement mortar contains the following components in the following proportions by mass fraction: 100 parts of slag cement raw material, 39-44.5 parts of water, 0.6-1 part of polycarboxylate superplasticizer, 0.3-0.5 part of superabsorbent polymer, 4-5 parts of activator, and 0.03-0.05 part of multi-walled carbon nanotube.

[0008] Further, the slag cement raw material contains the following components in the following proportions by mass percentage: 70wt% of alkali slag, 5-20wt% of cement, and 10-25wt% of gypsum.

[0009] Further, the alkali slag includes, in percentage by mass, 32.46wt% SiO2, 15.96wt% Al2O3, 38.63wt% CaO, 0.34wt% Fe2O3, 7.51wt% MgO, 0.30wt% Na2O, 0.40wt% K2O, 2.55wt% SO3, and 1.29wt% other components.

[0010] Further, the alkali slag, the cement, and the gypsum have a particle size of less than or equal to 70 microns.

[0011] Further, the activator includes, in percentage by mass, 33-56wt% NaOH, 40-55wt% Na2SO4, and 5-17wt% Na2O·1.5SiO2.

[0012] Further, the preparation method of the polycarboxylic acid water reducer includes the following steps:

[0013] S1: After drying the reaction container in vacuum, nitrogen is introduced, n-butanol and sodium methoxide are added, heated to 90-95°C for 20-25 minutes, heated to 120-121°C, ethylene oxide is added, heated to 130-160°C, and reacted for 2-4 hours under a pressure of 0.1-0.6 MPa, cooled to 120-121°C for aging for 30-35 minutes, discharged under reduced pressure, neutralized to neutral with acetic acid, and filtered with activated carbon in vacuum to obtain a polyether;

[0014] S2: The polyether, acrylic acid, p-toluenesulfonic acid, phenothiazine, and toluene are added to the reaction container, heated to 140-145°C for 12-13 hours, cooled to 90-92°C, and the toluene is removed with a circulating water vacuum pump to obtain esterified monomers;

[0015] S3: The esterified monomers, acrylic acid, and mercaptopropionic acid are added to deionized water and stirred uniformly to obtain solution A, ammonium persulfate is added to deionized water and stirred uniformly to obtain solution B, and sodium bisulfite is added to deionized water and stirred uniformly to obtain solution C, and the solution A, the solution B, and the solution C are sequentially added to the reaction container, heated to 60-65°C for 2-2.5 hours, cooled to room temperature, and the pH of the product is adjusted to 6-7 to obtain a polycarboxylic acid water reducer.

[0016] Further, the polycarboxylic acid water reducer has a solid content of 30%.

[0017] Further, in the preparation process of the polyether, the molar ratio of n-butanol, sodium methoxide, and ethylene oxide is 1:(0.05-0.1):(6-10).

[0018] Further, the preparation process of the esterified monomer includes that the proportion of each component is as follows in terms of mass fraction: 600-800 parts of polyether, 72-96 parts of acrylic acid, 20.2-26.9 parts of p-toluene sulfonic acid, 1.0-1.3 parts of phenothiazine, and 202-269 parts of toluene.

[0019] Further, the preparation process of the polycarboxylic acid water reducing agent includes that the proportion of each component is as follows in terms of mass fraction: 300-500 parts of esterified monomer, 36-60 parts of acrylic acid, 1.06-1.76 parts of mercaptopropionic acid, 3.36-5.6 parts of ammonium persulfate, and 3.06-5.1 parts of sodium bisulfite.

[0020] Further, the preparation method of the high water absorption polymer includes the following steps.

[0021] Methyl methacrylate, n-butyl methacrylate and acrylamide are added into N,N-dimethylformamide and stirred uniformly, and then nano-silica suspension, N,N'-methylene bisacrylamide and azobisisobutyronitrile are added and stirred uniformly, and then heated to 60-65 DEG C under argon atmosphere and reacted for 12-12.5 h, and then the product is added into deionized water for swelling, and then vacuum dried at 100-105 DEG C, and then ground to obtain the high water absorption polymer.

[0022] Further, in the preparation process of the high water absorption polymer, the molar ratio of methyl methacrylate, n-butyl methacrylate and acrylamide is 1:1:1, the addition amount of N,N'-methylene bisacrylamide is 0.4 mol% of the total monomer concentration, the addition amount of azobisisobutyronitrile is 0.5 mol% of the total monomer concentration, and the addition amount of nano-silica is 5-10 wt% of the total monomer mass.

[0023] A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps: premixing slag cement raw materials, a high water absorption polymer and multi-walled carbon nanotubes for 1-2 min, and then sequentially adding water, a polycarboxylic acid water reducing agent and an activator, and mixing at a low speed for 1-2 min and at a high speed for 3-5 min to obtain the crack-resistant cement mortar.

[0024] Further, the mixing speed at the low speed is 100-300 rpm, and the mixing speed at the high speed is 500-1200 rpm.

[0025] Further, the multi-walled carbon nanotube has a thickness of 30 nm, a diameter of 5-15 nm and a length of 48-78 nm.

[0026] Further, the nano-silica has a particle size of 50 nm.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] 1. This invention regulates water retention by combining nano-silica with superabsorbent polymers. The silicon-oxygen skeleton of nano-silica improves the structural rigidity of the superabsorbent polymer, and its surface hydroxyl groups adsorb water through hydrogen bonds. At the same time, the volcanic ash reaction of nanoparticles generates CSH gel, which is tightly connected with the matrix to form capillary channels, realizing continuous release of water driven by the water gradient, maintaining internal humidity, and reducing self-shrinkage stress.

[0029] 2. This invention utilizes a self-made shrinkage-reducing polycarboxylate superplasticizer, which enriches unreacted esterified macromonomers and unadsorbed polycarboxylate superplasticizer molecules in the pore solution, thereby reducing capillary stress; the hydrophobic modification of the side chains reduces the adsorption of C3A, inhibits the excessive formation of early AFt, and optimizes the pore structure.

[0030] 3. This invention further optimizes the ratio of the slag-gypsum-clinker system and the activator. On the one hand, it leverages the synergistic effect of nano-silica composite superabsorbent polymer (SAP) with the slag-gypsum-clinker system. Nano-silica, through physical adsorption and chemical grafting, embeds itself into the SAP network, enhancing its water absorption rate in alkaline environments and stabilizing the SAP structure through the rigidity of the silicon-oxygen framework. Simultaneously, the volcanic ash reaction of nano-silica generates CSH gel, which reacts with active Al2O3 and CaO in the slag to form stable ettringite (AFt), filling pores and increasing matrix density. On the other hand, it utilizes the synergistic effect of shrinkage-reducing polycarboxylate superplasticizer with the slag-gypsum system. Unreacted esterified macromonomers and unadsorbed molecules of the polycarboxylate superplasticizer accumulate in the pore solution, reducing surface tension and significantly lowering capillary stress. In the slag system, the low adsorption characteristics of the polycarboxylate superplasticizer cause it to remain more in the liquid phase, reacting with the Ca released from the slag. 2+ Al 3+ A dynamic equilibrium is formed, inhibiting the explosive crystallization of AFt and delaying the accumulation of shrinkage stress. The polycarboxylate superplasticizer prolongs the hydration induction period, delaying the rapid reaction of C3A and reducing the excessive formation of AFt in the early stage. The retarding properties of slag synergistically combine with the polycarboxylate superplasticizer to form a "double retarding effect," optimizing the hydration exothermic curve and reducing the risk of temperature stress cracking. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1: A method for preparing crack-resistant cement mortar containing slag, comprising the following steps:

[0033] S1: After the reaction container is vacuum dried, nitrogen is introduced, 1 mmol of n-butanol, 0.05 mmol of sodium methoxide are added, heated to 90 DEG C for 20 min, heated to 120 DEG C, 6 mmol of oxirane is added, heated to 130 DEG C, 0.2 MPa pressure for 3 h, cooled to 120 DEG C for 30 min, and the product is discharged under reduced pressure, neutralized with acetic acid to neutral, and the product is filtered with activated carbon under vacuum to obtain a polyether;

[0034] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluenesulfonic acid, 3.36 g of phenothiazine, and 202 g of toluene are added to the reaction container, heated to 140 DEG C for 12 h, cooled to 90 DEG C, and the toluene is removed by a circulating water vacuum pump to obtain an esterified monomer;

[0035] S3: 300 g of esterified monomer, 36 g of acrylic acid, 1.06 g of mercaptopropionic acid are added to 100 g of deionized water, stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate is added to 200 g of deionized water, stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite is added to 166 g of deionized water, stirred uniformly to obtain solution C; solution A, solution B, and solution C are sequentially added to the reaction container, heated to 60 DEG C for 2 h, cooled to room temperature, and the product pH is adjusted to 6 to obtain a polycarboxylic acid water reducer;

[0036] S4: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate, and 1 mmol of acrylamide are added to N,N-dimethylformamide, stirred uniformly, 1.5 g of nano-silica is added to a nano-silica suspension, 0.012 mmol of N,N'-methylenebisacrylamide, and 0.015 mmol of azobisisobutyronitrile are added, stirred uniformly, heated to 60 DEG C under argon atmosphere for 12 h, the product is added to deionized water for swelling, vacuum dried at 100 DEG C, and ground to obtain a superabsorbent polymer;

[0037] S5: 70 g of alkali slag, 5 g of cement, 25 g of gypsum, 0.3 g of superabsorbent polymer, and 0.03 g of multi-walled carbon nanotube are premixed for 1 min, 44.5 g of water, 0.6 g of polycarboxylic acid water reducer, and 4 g of activator are sequentially added, low-speed mixed for 1 min, and high-speed mixed for 3 min to obtain a crack-resistant cement mortar.

[0038] Example 2: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0039] S1: After the reaction container is vacuum dried, nitrogen is introduced, 1 mmol of n-butanol, 0.05 mmol of sodium methoxide are added, heated to 90 DEG C for 20 min, heated to 120 DEG C, 6 mmol of ethylene oxide is added, heated to 130 DEG C, 0.2 MPa pressure for 3 h, cooled to 120 DEG C for 30 min, and the product is discharged under reduced pressure, neutralized with acetic acid to neutral, and the product is filtered with activated carbon under vacuum to obtain a polyether;

[0040] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluenesulfonic acid, 3.36 g of phenothiazine, and 202 g of toluene are added to the reaction container, heated to 140 DEG C for 12 h, cooled to 90 DEG C, and the toluene is removed by a circulating water vacuum pump to obtain an esterified monomer;

[0041] S3: 300 g of esterified monomer, 36 g of acrylic acid, 1.06 g of mercaptopropionic acid are added to 100 g of deionized water, stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate is added to 200 g of deionized water, stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite is added to 166 g of deionized water, stirred uniformly to obtain solution C; solution A, solution B, and solution C are sequentially added to the reaction container, heated to 60 DEG C for 2 h, cooled to room temperature, and the product pH is adjusted to 6 to obtain a polycarboxylic acid water reducer;

[0042] S4: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate, and 1 mmol of acrylamide are added to N,N-dimethylformamide, stirred uniformly, 1.5 g of nano-silica is added to a nano-silica suspension, 0.012 mmol of N,N'-methylenebisacrylamide, and 0.015 mmol of azobisisobutyronitrile are added, stirred uniformly, heated to 60 DEG C under argon atmosphere for 12 h, the product is added to deionized water for swelling, vacuum dried at 100 DEG C, and ground to obtain a superabsorbent polymer;

[0043] S5: 70 g of alkali slag, 20 g of cement, 10 g of gypsum, 0.3 g of superabsorbent polymer, and 0.03 g of multi-walled carbon nanotube are premixed for 1 min, 44.5 g of water, 0.6 g of polycarboxylic acid water reducer, and 4 g of activator are sequentially added, low-speed mixed for 1 min, and high-speed mixed for 3 min to obtain a crack-resistant cement mortar.

[0044] Example 3: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0045] S1: After the reaction container is vacuum dried, nitrogen is introduced, 1 mmol of n-butanol and 1 mmol of sodium methoxide are added, heated to 90°C for 20 min, heated to 120°C, 10 mmol of oxirane is added, heated to 145°C, reacted for 3h under a pressure of 0.4 MPa, cooled to 120°C for 30 min, discharged under reduced pressure, the product is neutralized to neutral with acetic acid, and the product is filtered with activated carbon under vacuum to obtain a polyether;

[0046] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluenesulfonic acid, 3.36 g of phenothiazine, and 202 g of toluene are added to the reaction container, heated to 140°C for 12h, cooled to 90°C, and toluene is removed by a circulating water vacuum pump to obtain an esterified monomer;

[0047] S3: 300 g of esterified monomer, 36 g of acrylic acid, and 1.06 g of mercaptopropionic acid are added to 100 g of deionized water and stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate is added to 200 g of deionized water and stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite is added to 166 g of deionized water and stirred uniformly to obtain solution C; solution A, solution B, and solution C are sequentially added to the reaction container, heated to 60°C for 2h, cooled to room temperature, and the pH of the product is adjusted to 6 to obtain a polycarboxylic acid water reducer;

[0048] S4: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate, and 1 mmol of acrylamide are added to N,N-dimethylformamide, stirred uniformly, 1.5 g of nano-silica is added to a nano-silica suspension, 0.012 mmol of N,N'-methylenebisacrylamide, and 0.015 mmol of azobisisobutyronitrile are added, stirred uniformly, heated to 60°C for 12h under an argon atmosphere, the product is added to deionized water for swelling, vacuum dried at 100°C, and ground to obtain a superabsorbent polymer;

[0049] S5: 70 g of alkali slag, 20 g of cement, 10 g of gypsum, 0.3 g of superabsorbent polymer, and 0.03 g of multi-walled carbon nanotubes are premixed for 1 min, 44.5 g of water, 0.6 g of polycarboxylic acid water reducer, and 4 g of activator are sequentially added, low-speed mixed for 1 min, and high-speed mixed for 3 min to obtain a crack-resistant cement mortar.

[0050] Example 4: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0051] S1: After the reaction container is vacuum dried, nitrogen is introduced, 1 mmol of n-butanol and 1 mmol of sodium methoxide are added, heated to 90 DEG C for 20 min, heated to 120 DEG C, 10 mmol of oxirane is added, heated to 145 DEG C, 0.4 MPa pressure for 3 h, cooled to 120 DEG C for 30 min, and the product is discharged under reduced pressure, neutralized with acetic acid to neutral, and the product is filtered with activated carbon under vacuum to obtain a polyether;

[0052] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluenesulfonic acid, 3.36 g of phenothiazine, and 202 g of toluene are added to the reaction container, heated to 140 DEG C for 12 h, cooled to 90 DEG C, and the toluene is removed by a circulating water vacuum pump to obtain an esterified monomer;

[0053] S3: 300 g of the esterified monomer, 36 g of acrylic acid, and 1.06 g of mercaptopropionic acid are added to 100 g of deionized water and stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate is added to 200 g of deionized water and stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite is added to 166 g of deionized water and stirred uniformly to obtain solution C; solution A, solution B, and solution C are sequentially added to the reaction container, heated to 60 DEG C for 2 h, cooled to room temperature, and the pH of the product is adjusted to 6 to obtain a polycarboxylic acid water reducer;

[0054] S4: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate, and 1 mmol of acrylamide are added to N,N-dimethylformamide, stirred uniformly, 3 g of nano-silica is added to a nano-silica suspension, 0.012 mmol of N,N'-methylenebisacrylamide, and 0.015 mmol of azobisisobutyronitrile are added, stirred uniformly, heated to 60 DEG C under an argon atmosphere for 12 h, the product is swelled in deionized water, vacuum dried at 100 DEG C, and ground to obtain a superabsorbent polymer;

[0055] S5: 70 g of alkali slag, 20 g of cement, 10 g of gypsum, 0.3 g of superabsorbent polymer, and 0.03 g of multi-walled carbon nanotube are premixed for 1 min, 44.5 g of water, 0.6 g of polycarboxylic acid water reducer, and 4 g of activator are sequentially added, low-speed mixed for 1 min, and high-speed mixed for 3 min to obtain a crack-resistant cement mortar.

[0056] Example 5: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0057] S1: After the reaction container is vacuum dried, nitrogen is introduced, 1 mmol of n-butanol and 1 mmol of sodium methoxide are added, heated to 90°C for 20 min, heated to 120°C, 10 mmol of oxirane is added, heated to 145°C, reacted for 3h under a pressure of 0.4 MPa, cooled to 120°C for 30 min, discharged under reduced pressure, the product is neutralized to neutral with acetic acid, and the product is filtered with activated carbon under vacuum to obtain a polyether;

[0058] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluenesulfonic acid, 3.36 g of phenothiazine, and 202 g of toluene are added to the reaction container, heated to 140°C for 12h, cooled to 90°C, and toluene is removed by a circulating water vacuum pump to obtain an esterified monomer;

[0059] S3: 300 g of esterified monomer, 36 g of acrylic acid, and 1.06 g of mercaptopropionic acid are added to 100 g of deionized water and stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate is added to 200 g of deionized water and stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite is added to 166 g of deionized water and stirred uniformly to obtain solution C; solution A, solution B, and solution C are sequentially added to the reaction container, heated to 60°C for 2h, cooled to room temperature, and the pH of the product is adjusted to 6 to obtain a polycarboxylic acid water reducer;

[0060] S4: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate, and 1 mmol of acrylamide are added to N,N-dimethylformamide, stirred uniformly, 3 g of nano-silica is added to a nano-silica suspension, 0.012 mmol of N,N'-methylenebisacrylamide, and 0.015 mmol of azobisisobutyronitrile are added, stirred uniformly, heated to 60°C for 12h under an argon atmosphere, the product is swelled in deionized water, vacuum dried at 100°C, and ground to obtain a superabsorbent polymer;

[0061] S5: 70 g of alkali slag, 20 g of cement, 10 g of gypsum, 0.4 g of superabsorbent polymer, and 0.04 g of multi-walled carbon nanotube are premixed for 1 min, 42.2 g of water, 0.8 g of polycarboxylic acid water reducer, and 4 g of activator are sequentially added, low-speed mixed for 1 min, and high-speed mixed for 3 min to obtain a crack-resistant cement mortar.

[0062] Example 6: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0063] S1: After vacuum drying the reaction vessel, nitrogen was introduced, 1 mmol of n-butanol, 1 mmol of sodium methoxide were added, heated to 90 DEG C for 20 min, heated to 120 DEG C, 10 mmol of oxirane was added, heated to 145 DEG C, 0.4 MPa pressure for 3 h, cooled to 120 DEG C for 30 min, discharged under reduced pressure, the product was neutralized to neutral with acetic acid, the product was filtered with activated carbon under vacuum to obtain a polyether;

[0064] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluenesulfonic acid, 3.36 g of phenothiazine, 202 g of toluene were added to the reaction vessel, heated to 140 DEG C for 12 h, cooled to 90 DEG C, and toluene was removed by a circulating water vacuum pump to obtain an esterified monomer;

[0065] S3: 300 g of esterified monomer, 36 g of acrylic acid, 1.06 g of mercaptopropionic acid were added to 100 g of deionized water, stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate was added to 200 g of deionized water, stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite was added to 166 g of deionized water, stirred uniformly to obtain solution C; solution A, solution B, and solution C were sequentially added to the reaction vessel, heated to 60 DEG C for 2 h, cooled to room temperature, and the pH of the product was adjusted to 6 to obtain a polycarboxylic acid water reducer;

[0066] S4: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate, 1 mmol of acrylamide were added to N,N-dimethylformamide, stirred uniformly, 3 g of nano-silica containing nano-silica suspension, 0.012 mmol of N,N'-methylenebisacrylamide, and 0.015 mmol of azobisisobutyronitrile were added, stirred uniformly, heated to 60 DEG C under argon atmosphere for 12 h, the product was added to deionized water for swelling, vacuum dried at 100 DEG C, and ground to obtain a superabsorbent polymer;

[0067] S5: 70 g of alkali slag, 20 g of cement, 10 g of gypsum, 0.5 g of superabsorbent polymer, and 0.05 g of multi-walled carbon nanotubes were premixed for 1 min, 39 g of water, 1 g of polycarboxylic acid water reducer, and 4 g of activator were sequentially added, low-speed mixed for 1 min, and high-speed mixed for 3 min to obtain a crack-resistant cement mortar.

[0068] Comparative Example 1: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0069] S1: After vacuum drying the reaction container, nitrogen was introduced, 1 mmol of n-butanol, 0.05 mmol of sodium methoxide were added, heated to 90 DEG C for 20 min, heated to 120 DEG C, 6 mmol of oxirane was added, heated to 130 DEG C, reacted for 3 h under 0.2 MPa pressure, cooled to 120 DEG C for 30 min, discharged under reduced pressure, the product was neutralized to neutral with acetic acid, and the product was filtered with activated carbon under vacuum to obtain a polyether;

[0070] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluenesulfonic acid, 3.36 g of phenothiazine, and 202 g of toluene were added to the reaction container, heated to 140 DEG C for 12 h, cooled to 90 DEG C, and toluene was removed by a circulating water vacuum pump to obtain an esterified monomer;

[0071] S3: 300 g of the esterified monomer, 36 g of acrylic acid, 1.06 g of mercaptopropionic acid were added to 100 g of deionized water, stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate was added to 200 g of deionized water, stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite was added to 166 g of deionized water, stirred uniformly to obtain solution C; solution A, solution B, and solution C were sequentially added to the reaction container, heated to 60 DEG C for 2 h, cooled to room temperature, and the pH of the product was adjusted to 6 to obtain a polycarboxylic acid water reducer;

[0072] S4: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate were added to N,N-dimethylformamide, stirred uniformly, 0.012 mmol of N,N'-methylenebisacrylamide, 0.015 mmol of azobisisobutyronitrile were added, stirred uniformly, heated to 60 DEG C for 12 h under argon atmosphere, the product was swelled in deionized water, vacuum dried at 100 DEG C, and ground to obtain a superabsorbent polymer;

[0073] S5: 70 g of alkali slag, 5 g of cement, 25 g of gypsum, 0.3 g of superabsorbent polymer, and 0.03 g of multi-walled carbon nanotubes were premixed for 1 min, 44.5 g of water, 0.6 g of polycarboxylic acid water reducer, and 4 g of activator were sequentially added, low-speed mixed for 1 min, and high-speed mixed for 3 min to obtain a crack-resistant cement mortar.

[0074] Comparative Example 2: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0075] S1: After vacuum drying the reaction container, nitrogen was introduced, 1 mmol of n-butanol, 0.05 mmol of sodium methoxide were added, heated to 90 DEG C for 20 min, heated to 120 DEG C, 6 mmol of oxirane was added, heated to 130 DEG C, reacted for 3 h under 0.2 MPa pressure, cooled to 120 DEG C for 30 min, discharged under reduced pressure, the product was neutralized to neutral with acetic acid, and the product was filtered with activated carbon under vacuum to obtain a polyether;

[0076] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluene sulfonic acid, 3.36 g of phenothiazine, 202 g of toluene were added into a reaction vessel, heated to 140℃ for 12 h, cooled to 90℃, toluene was removed by a circulating water vacuum pump, to obtain an esterified monomer;

[0077] S3: 300 g of the esterified monomer, 36 g of acrylic acid, 1.06 g of mercaptopropionic acid were added into 100 g of deionized water, stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate was added into 200 g of deionized water, stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite was added into 166 g of deionized water, stirred uniformly to obtain solution C; solution A, solution B, and solution C were sequentially added into a reaction vessel, heated to 60℃ for 2 h, cooled to room temperature, and the pH of the product was adjusted to 6, to obtain a polycarboxylic acid water reducer;

[0078] S4: 70 g of alkali slag, 5 g of cement, 25 g of gypsum, and 0.03 g of multi-walled carbon nanotubes were premixed for 1 min, 44.5 g of water, 0.6 g of the polycarboxylic acid water reducer, and 4 g of an activator were sequentially added, low-speed mixing was performed for 1 min, and high-speed mixing was performed for 3 min, to obtain a crack-resistant cement mortar.

[0079] Comparative Example 3: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0080] S1: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate, and 1 mmol of acrylamide were added into N,N-dimethylformamide, stirred uniformly, 1.5 g of nano-silica was added into a nano-silica suspension, 0.012 mmol of N,N'-methylenebisacrylamide, and 0.015 mmol of azobisisobutyronitrile were added, stirred uniformly, heated to 60℃ for 12 h under an argon atmosphere, the product was added into deionized water for swelling, vacuum dried at 100℃, and ground, to obtain a superabsorbent polymer;

[0081] S2: 70 g of alkali slag, 5 g of cement, 25 g of gypsum, 0.3 g of the superabsorbent polymer, and 0.03 g of multi-walled carbon nanotubes were premixed for 1 min, 44.5 g of water, 0.6 g of the polycarboxylic acid water reducer PCA®-I, and 4 g of an activator were sequentially added, low-speed mixing was performed for 1 min, and high-speed mixing was performed for 3 min, to obtain a crack-resistant cement mortar.

[0082] Comparative Example 4: A preparation method of a crack-resistant cement mortar containing slag, comprising the following steps:

[0083] S1: After vacuum drying the reaction vessel, nitrogen was introduced, 1 mmol of n-butanol, 0.05 mmol of sodium methoxide were added, heated to 90 DEG C for 20 min, heated to 120 DEG C, 6 mmol of oxirane was added, heated to 130 DEG C, reacted for 3 h under 0.2 MPa pressure, cooled to 120 DEG C for 30 min, discharged under reduced pressure, the product was neutralized to neutral with acetic acid, and the product was filtered with activated carbon under vacuum to obtain a polyether;

[0084] S2: 600 g of polyether, 36 g of acrylic acid, 1.06 g of p-toluenesulfonic acid, 3.36 g of phenothiazine, and 202 g of toluene were added to the reaction vessel, heated to 140 DEG C for 12 h, cooled to 90 DEG C, and toluene was removed by a circulating water vacuum pump to obtain an esterified monomer;

[0085] S3: 300 g of the esterified monomer, 36 g of acrylic acid, and 1.06 g of mercaptopropionic acid were added to 100 g of deionized water and stirred uniformly to obtain solution A; 3.36 g of ammonium persulfate was added to 200 g of deionized water and stirred uniformly to obtain solution B; 3.06 g of sodium bisulfite was added to 166 g of deionized water and stirred uniformly to obtain solution C; solution A, solution B, and solution C were sequentially added to the reaction vessel, heated to 60 DEG C for 2 h, cooled to room temperature, and the pH of the product was adjusted to 6 to obtain a polycarboxylic acid water reducer;

[0086] S4: 1 mmol of methacrylic acid, 1 mmol of n-butyl methacrylate, and 1 mmol of acrylamide were added to N,N-dimethylformamide, stirred uniformly, 1.5 g of nano-silica was added to a nano-silica suspension, 0.012 mmol of N,N'-methylenebisacrylamide, and 0.015 mmol of azobisisobutyronitrile were added, stirred uniformly, heated to 60 DEG C under an argon atmosphere for 12 h, the product was swelled in deionized water, vacuum dried at 100 DEG C, and ground to obtain a superabsorbent polymer;

[0087] S5: 70 g of alkali slag, 5 g of cement, 25 g of gypsum, 0.3 g of superabsorbent polymer, and 0.03 g of multi-walled carbon nanotubes were premixed for 1 min, 44.5 g of water, 1.2 g of polycarboxylic acid water reducer, and 4 g of activator were sequentially added, low-speed mixed for 1 min, and high-speed mixed for 3 min to obtain a crack-resistant cement mortar.

[0088] Experiment: The performance of the crack-resistant cement mortar was tested according to the method described in JC / T603-2004 "Cement Mortar Dry Shrinkage Test Method". The shrinkage rate ε of the test piece was calculated i and the shrinkage reduction rate R.

[0089] ε i =L i -L0 / 250;

[0090] L0 is the initial length of the test piece, mm; L is the length of the test piece, mm. i L0 is the initial length of the test piece, mm; L is the length of the test piece, mm.

[0091] The experimental data are shown in Table 1.

[0092] Table 1: Anti-cracking performance test data of anti-cracking cement mortar

[0093] Shrinkage (7d) / % Shrinkage (28d) / % Example 1 0.09 0.16 Example 2 0.09 0.16 Example 3 0.08 0.16 Example 4 0.08 0.15 Example 5 0.07 0.15 Example 6 0.06 0.14 Comparative Example 1 0.11 0.19 Comparative Example 2 0.12 0.21 Comparative Example 3 0.14 0.23 Comparative Example 4 0.12 0.20

[0094] Conclusion: The anti-cracking cement mortar prepared by the application has excellent anti-cracking performance.

[0095] In Comparative Example 1, no nano-silicon dioxide is added to the high water-absorbing polymer, resulting in a decrease in the anti-cracking performance of the anti-cracking cement mortar; in Comparative Example 2, no high water-absorbing polymer is added, resulting in a decrease in the anti-cracking performance of the anti-cracking cement mortar; in Comparative Example 3, a common commercially available polycarboxylic acid water reducing agent is used, resulting in a decrease in the anti-cracking performance of the anti-cracking cement mortar; and in Comparative Example 4, an excess of polycarboxylic acid water reducing agent is used, resulting in a decrease in the anti-cracking performance of the anti-cracking cement mortar.

[0096] It will be obvious to a person skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments, and that the application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the application is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning and range of the equivalent elements of the claims are intended to be embraced by the application.

Claims

1. A crack-resistant cement mortar containing slag, characterized in that: The components of the crack-resistant cement mortar, by mass, include: 100 parts slag cement raw material, 39-44.5 parts water, 0.6-1 parts polycarboxylate superplasticizer, 0.3-0.5 parts superabsorbent polymer, 4-5 parts activator, and 0.03-0.05 parts multi-walled carbon nanotubes. The preparation method of the polycarboxylate superplasticizer includes the following steps: S1: After vacuum drying the reaction vessel, nitrogen gas is introduced, n-butanol and sodium methoxide are added, and the mixture is heated to 90-95℃ for 20-25 min. Then, the mixture is heated to 120-121℃, ethylene oxide is added, and the mixture is heated to 130-160℃. The mixture is then reacted at 0.1-0.6 MPa pressure for 2-4 h. The mixture is then cooled to 120-121℃ and aged for 30-35 min. The mixture is discharged under reduced pressure, and the product is neutralized to neutral using acetic acid. The product is then vacuum filtered using activated carbon to obtain polyether. S2: Add polyether, acrylic acid, p-toluenesulfonic acid, phenthiazide and toluene into a reaction vessel, heat to 140-145℃ and react for 12-13 hours, cool to 90-92℃, remove toluene using a circulating water vacuum pump to obtain the esterified monomer. S3: Add esterified monomer, acrylic acid, and mercaptopropionic acid to deionized water and stir until homogeneous to obtain solution A; add ammonium persulfate to deionized water and stir until homogeneous to obtain solution B; add sodium bisulfite to deionized water and stir until homogeneous to obtain solution C; add solutions A, B, and C sequentially to a reaction vessel, heat to 60-65℃ and react for 2-2.5 hours, cool to room temperature, and adjust the pH of the product to 6-7 to obtain polycarboxylate superplasticizer; The method for preparing the superabsorbent polymer includes the following steps: Methacrylic acid, n-butyl methacrylate, and acrylamide were added to N,N-dimethylformamide and stirred until homogeneous. Then, nano-silica suspension, N,N'-methylenebisacrylamide, and azobisisobutyronitrile were added and stirred until homogeneous. The mixture was heated to 60-65℃ under an argon atmosphere and reacted for 12-12.5h. The product was then added to deionized water to swell, dried under vacuum at 100-105℃, and ground to obtain a superabsorbent polymer. In the preparation of polyether, the molar ratio of n-butanol:sodium methoxide:ethylene oxide is 1:(0.05-0.1):(6-10); The proportions of each component in the preparation process of the esterified monomer, by mass parts, include: 600-800 parts polyether, 72-96 parts acrylic acid, 20.2-26.9 parts p-toluenesulfonic acid, 1.0-1.3 parts phenthiazide, and 202-269 parts toluene; The proportions of each component in the preparation process of polycarboxylate superplasticizer, by mass parts, include: 300-500 parts esterified monomer, 36-60 parts acrylic acid, 1.06-1.76 parts mercaptopropionic acid, 3.36-5.6 parts ammonium persulfate, and 3.06-5.1 parts sodium bisulfite; In the preparation of the superabsorbent polymer, the molar ratio of methacrylic acid: n-butyl methacrylate: acrylamide is 1:1:1; the amount of N,N'-methylenebisacrylamide added is 0.4 mol of the total monomer concentration; the amount of azobisisobutyronitrile added is 0.5 mol of the total monomer concentration; and the amount of nano silica added is 5-10 wt% of the total monomer mass.

2. The slag-containing crack-resistant cement mortar according to claim 1, characterized in that: The proportions of each component in the slag cement raw material, by mass percentage, include: 70wt% alkali slag, 5-20wt% cement, and 10-25wt% gypsum.

3. The slag-containing crack-resistant cement mortar according to claim 1, characterized in that: The components in the activator, by mass percentage, include: 33-56 wt% NaOH, 40-55% Na2SO4, and 5-17 wt% Na2O·1.5SiO2; the sum of the proportions of the components in the activator is 100%.

4. A method for preparing a slag-containing crack-resistant cement mortar according to any one of claims 1-3, characterized in that: Includes the following steps: Premix slag cement raw materials, superabsorbent polymer, and multi-walled carbon nanotubes for 1-2 minutes, then add water, polycarboxylate superplasticizer, and activator in sequence. Mix at low speed for 1-2 minutes and at high speed for 3-5 minutes to obtain crack-resistant cement mortar.