High-strength light-weight concrete thermal insulation wall building block and preparation method thereof

Abstract

The invention discloses a high-strength light-weight concrete thermal insulation wall building block and a preparation method thereof, and relates to the technical field of wall building blocks. The high-strength thermal insulation building block is prepared from the following components in parts by weight: 300 to 400 parts of Portland cement, 50 to 80 parts of fly ash, 20 to 30 parts of silica fume, 100 to 150 parts of light ceramsite, 50 to 80 parts of expanded perlite, 10 to 20 parts of nano calcium carbonate, 5 to 10 parts of glass fiber, 30 to 50 parts of graphene modified polystyrene particles, 3 to 5 parts of a water reducing agent and 0.5 to 1 part of an air entraining agent. By introducing the graphene modified polystyrene particles and the expanded perlite, strong interface bonding of the organic thermal insulation particles and the inorganic cement matrix is realized, and the compressive strength and thermal insulation performance of the building block are enhanced.

Description

Technical Field

[0001] This invention relates to the field of wall block technology, specifically to a high-strength lightweight concrete thermal insulation wall block and its preparation method. Background Technology

[0002] With the advancement of green building and energy conservation and emission reduction policies, the comprehensive demand for high strength, lightweight and high thermal insulation of wall materials is becoming increasingly urgent. Although traditional concrete blocks have high strength, they have high dry density and high thermal conductivity, making it difficult to meet the requirements of energy conservation and weight reduction. Existing lightweight blocks mostly achieve lightweight by increasing pores or lightweight aggregates, but this is often accompanied by problems such as decreased compressive strength and poor flexural performance, making them prone to cracking under stress.

[0003] Patent CN102108026B discloses a new type of lightweight ceramsite block wall material and its preparation method. The above patent achieves lightweight, low shrinkage, no cracking, and waterproof properties.

[0004] The aforementioned patents have achieved significant savings in cement usage, reduced heat of hydration, reduced concrete cracks caused by temperature stress, improved the microstructure of cement paste, increased concrete density, thereby improving concrete strength and durability, making the wall material lighter and extending its service life. However, there is still room for optimization in terms of high strength and thermal insulation.

[0005] Therefore, this application proposes a high-strength lightweight concrete insulated wall block with high strength and good thermal insulation performance, and a method for preparing the same. Summary of the Invention

[0006] The purpose of this invention is to provide a high-strength lightweight concrete insulation wall block and its preparation method, so as to solve the technical problems mentioned in the background art, such as low compressive strength, poor flexural performance, and easy cracking under stress of existing lightweight blocks.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a high-strength lightweight concrete thermal insulation wall block, comprising a high-strength thermal insulation block, wherein the high-strength thermal insulation block comprises the following components by weight: 300-400 parts silicate cement, 50-80 parts fly ash, 20-30 parts silica fume, 100-150 parts lightweight ceramsite, 50-80 parts expanded perlite, 10-20 parts nano-calcium carbonate, 5-10 parts glass fiber, 30-50 parts graphene-modified polystyrene particles, 3-5 parts water-reducing agent, and 0.5-1 part air-entraining agent. The preparation method of the high-strength thermal insulation block includes the following steps:

[0008] Step 1: Pour silicate cement, fly ash, silica fume and nano calcium carbonate into a mixer and dry mix for 5 minutes until uniform to form a mixed cementitious material;

[0009] Step 2: Place lightweight ceramsite, expanded perlite, and graphene-modified polystyrene particles into a low-speed mixer and mix for 3 minutes to obtain a lightweight aggregate mixture.

[0010] Step 3: Pour the mixture of cementitious material and lightweight aggregate into a mixer, add glass fiber and dry mix for 3 minutes, then add an aqueous solution containing water-reducing agent and air-entraining agent and wet mix for 5 minutes until the slurry is uniform. Pour the slurry into a mold and shape it. After standing for 24 hours, demold it and place it in a standard curing room for 28 days to obtain high-strength thermal insulation blocks.

[0011] Preferably, the lightweight ceramsite is sieved through a 5mm sieve and then soaked in deionized water for 24 hours, with the water changed every 8 hours. After soaking, it is dried at 105℃ to constant weight. The expanded perlite is sieved through a 2mm sieve and then mixed with a 3% (w / w) ethanol solution of silane coupling agent KH-550. The mixture is stirred at 60℃ for 1 hour, filtered, and then dried at 105℃ for 2 hours.

[0012] Preferably, the glass fiber is alkali-resistant, with a length of 15 mm. It is soaked in a 5% hydrochloric acid solution for 30 minutes, then washed with deionized water until neutral, and then dried at 60°C for 1 hour.

[0013] Preferably, the method for preparing the graphene-modified polystyrene particles includes the following steps:

[0014] Polystyrene particles were placed in a 5% ethanol solution and ultrasonically cleaned for 30 minutes to remove surface impurities. After drying, a 5% graphene dispersion with a graphene content of 2 wt% was added, and the mixture was mechanically stirred for 60 minutes.

[0015] Then, silane coupling agent KH550 was added at a rate of 2% of the mass of the polystyrene particles, and the mixture was reacted in a water bath at 60°C for 3 hours. After the reaction was completed, the mixture was filtered and dried to obtain graphene-modified polystyrene particles.

[0016] Preferably, the method for preparing the water-reducing agent includes the following steps:

[0017] Pour acrylic acid, polyethylene glycol methacrylate, sodium allyl sulfonate and deionized water into a four-necked flask and stir well. Then dissolve ammonium persulfate in deionized water to prepare an initiator solution. Place the flask in a 65°C water bath and set the stirring speed to 300 r / min.

[0018] Then, add 1 / 3 of the initiator solution and react for 10 minutes. Then, start adding the remaining initiator solution and the remaining monomer mixture dropwise at a rate of 2 mL / min for 2 hours. After the addition is complete, raise the temperature to 75°C, keep the reaction at this temperature for 1.5 hours, and then cool it to 40°C. Adjust the pH to 7 with a 30% sodium hydroxide solution to obtain the water-reducing agent.

[0019] Preferably, the method for preparing the air-entraining agent includes the following steps:

[0020] After rosin is crushed to a particle size of 2 mm, it is put into a reaction vessel equipped with a stirrer, a 30% sodium hydroxide solution is added, the temperature is raised to 80°C, and then the saponification reaction is carried out by stirring at 300 r / min for 1 h.

[0021] After the reaction was completed, the temperature was lowered to 60°C, and a 37% formaldehyde solution was slowly added dropwise over 30 minutes. After the addition was complete, the temperature was raised to 90°C and the reaction was continued for 2 hours. Then, sodium dodecylbenzenesulfonate was added and stirred for 30 minutes. Triethanolamine was then added, and the reaction was maintained at 60°C for 1 hour. Finally, the mixture was cooled to room temperature, diluted with deionized water, and the pH was adjusted to 9 to obtain the air-entraining agent.

[0022] Preferably, the method for preparing the nano-calcium carbonate includes the following steps:

[0023] Limestone was crushed to a particle size of 50 mm and calcined at 1000℃ for 2 hours to produce quicklime. The quicklime was added to hot water at 80℃ at a solid-liquid ratio of 1:8. After 30 minutes, impurities were removed by sieving to obtain a calcium hydroxide suspension with a concentration of 1.2 mol / L.

[0024] The suspension was cooled to 25°C, and a mixed gas containing 20% ​​CO2 was introduced. The ratio of CO2 to N2 was 1:4, and the gas flow rate was set to 0.5 m³ / min. 3 / h, while adding 0.5% by mass of sucrose as a crystal form control agent, and maintaining a stirring speed of 300 r / min during the reaction;

[0025] When the pH dropped to 7.5, the aeration was stopped, and 1% stearic acid was added. The mixture was stirred at 60°C for 30 minutes to modify the surface. The reaction product was then filtered, dried at 80°C, and pulverized by air jet to obtain nano-calcium carbonate with an average particle size of 50 nm.

[0026] Preferably, the method for preparing the silicate cement includes the following steps:

[0027] Limestone, clay, and iron ore powder were mixed in a mass ratio of 85:12:3, crushed to a particle size of 5 mm, and fed into a raw meal mill. Water was added and the mixture was ground to a particle size of 80 μm to obtain a raw meal slurry. The slurry was spray-dried and then fed into a rotary kiln, where it was heated to 1450°C at a rate of 5°C / min and calcined for 30 minutes to produce clinker. After cooling to room temperature, the clinker was mixed with 5% dihydrate gypsum and ground in a cement mill to a specific surface area of ​​350 m² / g. 2 / kg, and then sieved to obtain silicate cement.

[0028] Preferably, the preparation method includes the following steps:

[0029] S1. According to the formula, take silicate cement, fly ash, silica fume and nano calcium carbonate and pour them into the mixer. Set the mixing speed to 300 r / min and dry mix for 5 minutes. During this period, scrape off the residual material on the inner wall of the mixer with a scraper every 1 minute to finally obtain the mixed cementitious material.

[0030] S2. Soak the lightweight ceramsite in deionized water for 24 hours, changing the water every 8 hours. After soaking, drain the ceramsite with a filter until there is no free water on the surface. Take the treated lightweight ceramsite, expanded perlite, and graphene-modified polystyrene particles, pour them into a mixer, set the speed to 120 r / min, and stir for 3 minutes. Take a sample to observe the uniformity of the mixture, ensuring that there is no obvious stratification of the three aggregates, and obtain a lightweight aggregate mixture.

[0031] Preferably, the preparation method further includes the following steps:

[0032] S3. Pour the mixture of cementitious material and lightweight aggregate into the mixer, add glass fiber according to the formula, set the speed to 150 r / min and dry mix for 3 minutes. Then dissolve the water-reducing agent and air-entraining agent in water to make a solution, pour it into the mixer, adjust the speed to 200 r / min and wet mix for 5 minutes, and stir until the slurry is in a uniform flow state.

[0033] S4. Pour the slurry into a steel mold, place it on a vibrating table and vibrate at a frequency of 50Hz and an amplitude of 0.5mm for 1 minute. Scrape the surface of the mold with a scraper and cover it with a plastic film. Let it stand in a 20℃ environment for 24 hours. After demolding, number the blocks and place them in a standard curing room. Maintain the temperature at 20℃ and spray the surface with water 3 times a day to keep it moist. Take them out after curing for 28 days.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. This invention achieves a strong interfacial bond between organic thermal insulation particles and inorganic cement matrix by introducing graphene-modified polystyrene particles and expanded perlite. It utilizes the closed-cell structure of polystyrene to reduce the thermal conductivity and maintains high compressive strength through the coordination effect of graphene, thus solving the problems of poor thermal insulation and low strength of traditional blocks.

[0036] 2. This invention introduces glass fibers treated with silane coupling agents, achieving chemical bonding between the fibers and the matrix, significantly improving flexural strength and enhancing the crack resistance of the blocks, thus solving the problems of traditional blocks being prone to cracking under external forces and having insufficient flexural strength.

[0037] 3. By introducing nano-calcium carbonate, this invention achieves directional regulation of the hydration process, promotes uniform growth of CSH gel, refines the pore structure, improves the density and volume stability of the block structure, and solves the problems of high porosity and large shrinkage caused by uneven hydration of cement stone.

[0038] 4. This invention achieves the reduction of block dry density while maintaining high strength by introducing an air-entraining agent and lightweight ceramsite. The air-entraining agent introduces closed air bubbles, reducing the proportion of dense matrix, and the porous structure of lightweight ceramsite replaces part of the cement stone. The dual effects work together to reduce weight, solving the problem that traditional block lightweighting requires sacrificing strength. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the block preparation process of the present invention;

[0040] Figure 2 This is a schematic diagram of the preparation process of the hybrid cementitious material of the present invention;

[0041] Figure 3 This is a schematic diagram of the preparation process of the lightweight aggregate mixture of the present invention; Detailed Implementation

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Implementation 1, please refer to Figure 1 and Figure 2 The present invention provides an embodiment of a high-strength lightweight concrete thermal insulation wall block, the preparation method of which includes the following steps:

[0044] S1. Weigh 400 parts of silicate cement, 80 parts of fly ash, 30 parts of silica fume, and 20 parts of nano calcium carbonate by weight, pour them into a mixer, dry mix at 300 r / min for 5 min, scraping the wall once every 1 min during the process, to obtain a mixed cementitious material.

[0045] S2. Take 150 parts of lightweight ceramsite and soak it in deionized water for 24 hours. After draining, mix it with 80 parts of expanded perlite and 50 parts of graphene-modified polystyrene particles. Stir at 120 r / min for 3 minutes to obtain a lightweight aggregate mixture.

[0046] S3. Pour the mixture of cementitious material and lightweight aggregate into a mixer, add 10 parts of glass fiber, dry mix at 150 r / min for 3 min, then add 5 parts of water-reducing agent and 1 part of air-entraining agent, wet mix at 200 r / min for 5 min, then pour the slurry into a mold, vibrate the mold at a 50 Hz vibration frequency for 50 s, then cover with a film and let stand for 24 h, after demolding, standard curing for 28 days to obtain high-strength lightweight concrete thermal insulation wall blocks.

[0047] Furthermore, when C3S (3CaO・SiO2) in silicate cement comes into contact with water, it first undergoes surface dissolution, and Ca... 2+ and SiO4 4- When ions enter the solution, the initial reaction rate is extremely fast. Subsequently, the ion concentration accumulates to saturation, and CSH gel begins to nucleate on the particle surface, forming a fibrous structure. Then, C3S rapidly hydrates, generating a large amount of CSH gel and Ca(OH)2 crystals. The Ca(OH)2 crystals fill the gaps between the CSH gels.

[0048] Meanwhile, the reaction rate of C3S (3CaO・SiO2) in silicate cement is relatively slow, but it continues to hydrate during the 28-day curing period, generating a denser CSH gel, which provides long-term strength support for the blocks. The active SiO2 and Al2O3 in fly ash initiate secondary hydration in an alkaline environment. The Ca(OH)2 generated by the hydration of C3S (3CaO・SiO2) acts as an alkali activator, reacting with the SiO2 on the surface of fly ash particles to generate additional CSH gel. Ca(OH)2 reacts with Al2O3 to generate hydrated calcium aluminate. The reaction consumes the large Ca(OH)2 crystals, and the generated small-particle products fill the 100nm cement stone pores, reducing defects in the interface transition zone.

[0049] The small particle size of silica fume allows it to penetrate into the nanoscale gaps of CSH gel. The highly reactive SiO2 in silica fume can react rapidly with Ca(OH)2 to generate high-density CSH gel, reducing the porosity between gels. Nano-calcium carbonate adsorbs Ca through surface charge. 2+ and SiO4 4- It becomes the nucleation center of CSH gel, making gel growth more uniform and avoiding local aggregation to form defects. Under the synergistic effect of multiple effects, the compressive strength of the block reaches 32.5MPa, while reducing the total porosity and significantly improving the structural compactness and mechanical properties.

[0050] Example 2, please refer to Figure 1The present invention provides an embodiment of a high-strength lightweight concrete thermal insulation wall block, the preparation method of which includes the following steps:

[0051] S1. Weigh out 350 parts of silicate cement, 65 parts of fly ash, 25 parts of silica fume, and 15 parts of nano calcium carbonate by weight, pour them into a mixer, dry mix at 300 r / min for 5 min, scraping the wall once every 1 min during the process, to obtain a mixed cementitious material.

[0052] S2. Take 120 parts of lightweight ceramsite and soak it in deionized water for 24 hours. After draining, mix it with 65 parts of expanded perlite and 40 parts of graphene-modified polystyrene particles. Stir at 120 r / min for 3 minutes to obtain a lightweight aggregate mixture.

[0053] S3. Pour the mixture of cementitious material and lightweight aggregate into a mixer, add 8 parts of glass fiber, dry mix at 150 r / min for 3 min, then add 4 parts of water-reducing agent and 0.8 parts of air-entraining agent, wet mix at 200 r / min for 5 min, then pour the slurry into a mold, vibrate the mold at a 50 Hz vibration frequency for 50 s, then cover with a film and let stand for 24 h. After demolding, standard curing for 28 days yields high-strength lightweight concrete thermal insulation wall blocks.

[0054] Furthermore, after treatment with the silane coupling agent KH-560, the glass fiber undergoes a dual chemical reaction on its surface. The first reaction occurs when the siloxane groups in the KH-560 molecule hydrolyze into silanol groups in the alkaline environment of the cement paste. These silanol groups then condense with the hydroxyl groups (-OH) on the glass fiber surface, forming stable -Si-O-Si- covalent bonds, tightly anchoring the coupling agent to the fiber surface. The second reaction occurs when the epoxy group (-C2H3O) at the other end of the coupling agent reacts with the Ca(OH)2 crystals generated during cement hydration. After the epoxy ring opens, it reacts with the Ca... 2+ Coordination forms -Si-O-Ca- chemical bonds, connecting the fiber to the matrix through chemical chains;

[0055] Meanwhile, the hydroxyl groups remaining on the fiber surface form dense hydrogen bonds with the hydroxyl groups (-OH) in the CSH gel, further enhancing the interfacial forces. The dual combination fills the interfacial transition zone with dense CSH gel. Under electron microscopy, the fiber surface is seen to be continuously wrapped with hydration products without obvious gaps. When the block is bent and microcracks are generated, the glass fiber crosses the two ends of the crack through bridging, transferring the stress from the cement matrix to the high tensile strength fiber, thus relieving the stress concentration at the crack tip.

[0056] When the crack extends to the fiber interface, the strong interfacial bonding force prevents the fiber from separating from the matrix until the fiber is broken. The synergistic effect increases the flexural strength of the block to 4.5 MPa, significantly improving the crack resistance and impact resistance of the block.

[0057] Example 3, please refer to Figure 1 and Figure 3 The present invention provides an embodiment of a high-strength lightweight concrete thermal insulation wall block, the preparation method of which includes the following steps:

[0058] S1. Weigh out 300 parts of silicate cement, 50 parts of fly ash, 20 parts of silica fume, and 10 parts of nano calcium carbonate by weight, pour them into a mixer, dry mix at 300 r / min for 5 min, scraping the wall once every 1 min during the process, to obtain a mixed cementitious material.

[0059] S2. Take 100 parts of lightweight ceramsite and soak it in deionized water for 24 hours. After draining, mix it with 50 parts of expanded perlite and 30 parts of graphene-modified polystyrene particles. Stir at 120 r / min for 3 minutes to obtain a lightweight aggregate mixture.

[0060] S3. Pour the mixture of cementitious material and lightweight aggregate into a mixer, add 5 parts of glass fiber, dry mix at 150 r / min for 3 min, then add 3 parts of water-reducing agent and 0.5 parts of air-entraining agent, wet mix at 200 r / min for 5 min, then pour the slurry into a mold, vibrate the mold at a 50 Hz vibration frequency for 50 s, then cover with a film and let stand for 24 h. After demolding, standard curing for 28 days yields high-strength lightweight concrete thermal insulation wall blocks.

[0061] Furthermore, the carboxylic acid groups (-COOH) in the air-entraining agent ionize in the strongly alkaline environment of the cement paste, generating negatively charged carboxylate ions (-COO₂). - Carboxylate ions are directionally adsorbed at the gas-liquid interface to form a monolayer. The hydrophilic carboxylate ions face the aqueous phase, while the hydrophobic carbon chains face the gas phase, which reduces the surface tension and significantly lowers the energy barrier for air entrainment.

[0062] Simultaneously, the mechanical shear force during stirring breaks the air into tiny bubbles. The air-entraining agent molecules rapidly coat the bubble surface, forming a rigid film structure. The hydrophobic interactions between molecules enhance the film's toughness, and the negative charge repulsion prevents bubble collisions and coalescence. At the same time, synergistic electrostatic repulsion occurs with the water-reducing agent adsorbed on the cement particle surface, preventing the bubbles from being crushed by the cement particles. The resulting bubbles are concentrated around 50µm in diameter, uniformly distributed in a spherical shape, accounting for 5% of the total volume. This avoids the strength loss caused by excessively large bubbles and creates continuous insulating channels through their dense distribution. The bubbles replace the dense matrix, reducing the dry density to 1280 kg / m³. 3 Meanwhile, the thermal conductivity of air is much lower than that of cement stone, reducing the thermal conductivity of the blocks to 0.120 W / (m·K), thus achieving a synergistic optimization of lightweighting and thermal insulation.

[0063] Example 4, please refer to Figure 1 and Figure 3The present invention provides an embodiment of a high-strength lightweight concrete thermal insulation wall block, the preparation method of which includes the following steps:

[0064] S1. Weigh out 380 parts of silicate cement, 70 parts of fly ash, 28 parts of silica fume, and 18 parts of nano calcium carbonate by weight, pour them into a mixer, dry mix at 300 r / min for 5 min, scraping the wall once every 1 min during the process, to obtain a mixed cementitious material.

[0065] S2. Polystyrene particles are placed in a 5% ethanol solution and ultrasonically cleaned for 30 minutes to remove surface impurities. After drying, a 5% graphene dispersion with a graphene content of 2 wt% is added. The mixture is mechanically stirred for 60 minutes, and then silane coupling agent KH550 is added at a dosage of 2% of the polystyrene particle mass. The mixture is reacted in a 60℃ water bath for 3 hours. After the reaction, the mixture is filtered and dried to obtain graphene-modified polystyrene particles. 140 parts of lightweight ceramsite are soaked in deionized water for 24 hours, drained, and then mixed with 70 parts of expanded perlite and 45 parts of graphene-modified polystyrene particles. The mixture is stirred at 120 r / min for 3 minutes to obtain a lightweight aggregate mixture.

[0066] S3. Pour the mixture of cementitious material and lightweight aggregate into a mixer, add 9 parts of glass fiber, dry mix at 150 r / min for 3 min, then add 4.5 parts of water-reducing agent and 0.8 parts of air-entraining agent, wet mix at 200 r / min for 5 min, then pour the slurry into a mold, vibrate the mold at a 50 Hz vibration frequency for 50 s, then cover with a film and let stand for 24 h. After demolding, standard curing for 28 days yields high-strength lightweight concrete thermal insulation wall blocks.

[0067] Furthermore, the electron cloud of graphene sheets possesses strong coordination ability, which interacts with Ca generated during cement hydration. 2+ Stable cation coordination bonds are formed, which can effectively transfer interfacial stress. At the same time, the amino group (-NH2) in the silane coupling agent KH550 coated on the particle surface undergoes a condensation reaction with the hydroxyl group (-OH) of the CSH gel to form a -Si-OC- chemical bridge bond. The thickness of the interfacial transition zone between the organic particles and the inorganic matrix is ​​reduced through the chemical bridge bond.

[0068] The strong interfacial bonding formed by chemical bonds makes the particles less prone to debonding under stress. Instead, the elastic deformation of polystyrene absorbs energy. Furthermore, the high thermal conductivity of graphene (5000 W / (m·K)) forms a continuous thermally conductive network on the particle surface, which can reflect and scatter heat, thus forming a thermal barrier. In the closed-cell structure of polystyrene, the thermal conductivity of the enclosed air is 0.026 W / (m·K), which, together with graphene, constructs a dual heat insulation system that combines reflection and barrier.

[0069] Example 5, please refer to Figure 1 and Figure 2 The present invention provides an embodiment of a high-strength lightweight concrete thermal insulation wall block, the preparation method of which includes the following steps:

[0070] S1. Weigh out 320 parts of silicate cement, 60 parts of fly ash, 22 parts of silica fume, and 12 parts of nano calcium carbonate by weight, pour them into a mixer, dry mix at 300 r / min for 5 min, scraping the wall once every 1 min during the process, to obtain a mixed cementitious material.

[0071] S2. Take 110 parts of lightweight ceramsite and soak it in deionized water for 24 hours. After draining, mix it with 60 parts of expanded perlite and 35 parts of graphene-modified polystyrene particles. Stir at 120 r / min for 3 minutes to obtain a lightweight aggregate mixture.

[0072] S3. Pour the mixture of cementitious material and lightweight aggregate into a mixer, add 6 parts of glass fiber, dry mix at 150 r / min for 3 min, then add 3.5 parts of water-reducing agent and 0.6 parts of air-entraining agent, wet mix at 200 r / min for 5 min, then pour the slurry into a mold, vibrate the mold at a 50 Hz vibration frequency for 50 s, then cover with a film and let stand for 24 h. After demolding, standard curing for 28 days yields high-strength lightweight concrete thermal insulation wall blocks.

[0073] Furthermore, nano-calcium carbonate has an extremely small particle size, and after being uniformly dispersed in cement paste, it exhibits a significant nucleation effect. The nano-calcium carbonate particles adsorb a large amount of Ca through their high surface energy. 2+ This creates localized areas of high calcium ion concentration, which in turn attracts SiO4 produced by the hydration of surrounding cement. 4- and AlO 2⁻ Ions become the core of CSH gel growth, guiding the originally randomly growing CSH gel to converge and deposit in an orderly manner along the surface of nano-calcium carbonate.

[0074] Meanwhile, cement hydration generates Ca(OH)2, which easily forms coarse, plate-like crystals, leading to structural defects. Nano-calcium carbonate can promote the decomposition of Ca(OH)2 into Ca... 2+ With OH - It participates in the synthesis of CSH gel, transforming more disordered Ca(OH)2 into a dense CSH gel network, thereby making the hydration products more evenly distributed, refining large pores into multiple micro pores, improving the overall density. At the same time, the increase in CSH gel enhances the intermolecular forces and the compressive strength of the block, making the block structure more stable, reducing water migration, and effectively inhibiting the drying shrinkage of the block.

[0075] Comparative Example 1: A high-strength, lightweight concrete insulated wall block, the preparation method of which includes the following steps:

[0076] S1. Weigh out 350 parts of silicate cement, 65 parts of fly ash, 25 parts of silica fume, and 15 parts of nano calcium carbonate by weight, pour them into a mixer, dry mix at 300 r / min for 5 min, scraping the wall once every 1 min during the process, to obtain a mixed cementitious material.

[0077] S2. Take 120 parts of lightweight ceramsite and soak it in deionized water for 24 hours. After draining, mix it with 65 parts of expanded perlite and stir at 120 r / min for 3 minutes to obtain a lightweight aggregate mixture.

[0078] S3. Pour the mixture of cementitious material and lightweight aggregate into a mixer, add 8 parts of glass fiber, dry mix at 150 r / min for 3 min, then add 4 parts of water-reducing agent and 0.8 parts of air-entraining agent, wet mix at 200 r / min for 5 min, then pour the slurry into a mold, vibrate the mold at a 50 Hz vibration frequency for 50 s, then cover with a film and let stand for 24 h. After demolding, standard curing for 28 days yields high-strength lightweight concrete thermal insulation wall blocks.

[0079] Comparative Example 2, a high-strength lightweight concrete thermal insulation wall block, the preparation method of which includes the following steps:

[0080] S1. Weigh out 350 parts of silicate cement, 65 parts of fly ash, 25 parts of silica fume, and 15 parts of nano calcium carbonate by weight, pour them into a mixer, dry mix at 300 r / min for 5 min, scraping the wall once every 1 min during the process, to obtain a mixed cementitious material.

[0081] S2. Take 120 parts of lightweight ceramsite and soak it in deionized water for 24 hours. After draining, mix it with 65 parts of expanded perlite and 40 parts of graphene-modified polystyrene particles. Stir at 120 r / min for 3 minutes to obtain a lightweight aggregate mixture.

[0082] S3. Pour the mixture of cementitious material and lightweight aggregate into a mixer and dry mix at 150 r / min for 3 min. Then add 4 parts of water-reducing agent and 0.8 parts of air-entraining agent and wet mix at 200 r / min for 5 min. Then pour the slurry into a mold and vibrate the mold at a vibration frequency of 50 Hz for 50 s. After that, cover it with a film and let it stand for 24 h. After demolding, standard curing for 28 days will yield high-strength lightweight concrete thermal insulation wall blocks.

[0083] Performance testing

[0084] Test 1 Mechanical property test: The blocks prepared in Examples 1-5 and Comparative Examples 1-2 were cut into 100mm×100mm×100mm cubes and 100mm×100mm×400mm prisms. The cubes were used for compressive strength testing, and the prisms were used for flexural strength testing. The compressive strength test was conducted using a compression testing machine. The maximum pressure at which the cubes failed was recorded, and the compressive strength was calculated. The flexural strength test was conducted using a flexural testing machine. The maximum load at which the prisms failed was recorded, and the flexural strength was calculated.

[0085] Test 2 Dry density test: The blocks prepared in Examples 1-5 and Comparative Examples 1-2 were sanded smooth with sandpaper, their mass was weighed, and their length, width and height were measured with vernier calipers to calculate the volume. The blocks were placed in an oven at 105℃ and dried to constant weight. The dried mass was weighed again and the dry density was calculated.

[0086] Test 3 Thermal conductivity test: The blocks prepared in Examples 1-5 and Comparative Examples 1-2 were dried in an oven at 105℃ to constant weight. The thermal conductivity was measured using a thermal conductivity meter with the hot plate method. The hot and cold plate temperatures were set to 25℃ and 15℃ respectively, with a temperature difference of 10℃. After the heat flow stabilized, the heat flow density, temperature difference and block thickness were recorded, and the thermal conductivity was calculated.

[0087] Test 4 Shrinkage test: The blocks prepared in Examples 1-5 and Comparative Examples 1-2 were cut into prism blocks of 100mm×100mm×500mm. After demolding, the initial length was measured, and then the length change was measured at 14 days and 28 days of curing, respectively, and the drying shrinkage rate was calculated.

[0088] Table 1. Test results of block performance testing

[0089]

[0090] Summary and Analysis

[0091] In terms of mechanical properties, the compressive strength of the examples (26.3-32.5 MPa) was higher than that of the comparative examples (20.1-25.6 MPa), and the flexural strength of the examples (4.2-4.8 MPa) was higher than that of the comparative examples (2.8-3.6 MPa). In particular, Example 1 had the highest glass fiber content and sufficient cementitious material, resulting in the best strength. This demonstrates that the bridging effect of glass fiber and the densification effect of the ternary cementitious system significantly improved the mechanical properties.

[0092] Regarding lightweighting and thermal insulation, the dry density of the embodiments is 1280-1420 kg / m³. 3 Comparison Example 1 (1480 kg / m³) 3The thermal conductivity of the graphene-modified polystyrene particles in Example 1 is much lower than that in Comparative Example 1 (0.168 W / (m·K)). Example 1 achieved a good thermal insulation effect because it had the highest content of graphene-modified polystyrene particles and the lowest thermal conductivity.

[0093] Regarding shrinkage performance, the shrinkage rate of the examples (0.035-0.042%) was less than that of the comparative examples (0.045-0.052%), indicating that the effect of nano-calcium carbonate in refining hydration products and reducing porosity effectively inhibited drying shrinkage.

[0094] In summary, the blocks of this invention achieve a combination of advantages including high strength, lightweight, low thermal conductivity, and low shrinkage, thus meeting the comprehensive performance requirements of wall materials for energy-efficient buildings.

[0095] Working principle: Silicate cement, fly ash and silica fume hydrate to form CSH gel. Nano-calcium carbonate acts as a crystal nucleus to promote uniform growth of the gel and fill the pores. Glass fibers are anchored in the matrix through interfacial chemical bonds and hydrogen bonds. When under stress, they bridge microcracks and transfer stress from the matrix to the fibers, inhibiting crack propagation and improving the flexural and compressive strength of the blocks.

[0096] The porous structure of lightweight ceramsite and expanded perlite reduces the density of the blocks, while the closed-cell structure of graphene-modified polystyrene particles further reduces weight. The microbubbles introduced by the air-entraining agent reduce the proportion of dense matrix, thus achieving lightweight structural optimization.

[0097] The low thermal conductivity of graphene-modified polystyrene particles, the porous air layer of expanded perlite, and the still air inside the bubbles form a three-level insulation system, which significantly reduces heat transfer and achieves the comprehensive performance of high strength, low weight, and excellent thermal insulation of the blocks.

[0098] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A high-strength lightweight concrete insulation wall block, comprising high-strength insulation blocks, characterized in that: The high-strength thermal insulation block comprises the following components by weight: 300-400 parts silicate cement, 50-80 parts fly ash, 20-30 parts silica fume, 100-150 parts lightweight ceramsite, 50-80 parts expanded perlite, 10-20 parts nano-calcium carbonate, 5-10 parts glass fiber, 30-50 parts graphene-modified polystyrene particles, 3-5 parts water-reducing agent, and 0.5-1 part air-entraining agent. The preparation method of the high-strength thermal insulation block includes the following steps: Step 1: Pour silicate cement, fly ash, silica fume and nano calcium carbonate into a mixer and dry mix for 5 minutes until uniform to form a mixed cementitious material; Step 2: Place lightweight ceramsite, expanded perlite, and graphene-modified polystyrene particles into a low-speed mixer and mix for 3 minutes to obtain a lightweight aggregate mixture. Step 3: Pour the mixture of cementitious material and lightweight aggregate into a mixer, add glass fiber and dry mix for 3 minutes, then add an aqueous solution containing water-reducing agent and air-entraining agent and wet mix for 5 minutes until the slurry is uniform. Pour the slurry into a mold and shape it. After standing for 24 hours, demold it and place it in a standard curing room for 28 days to obtain high-strength thermal insulation blocks.

2. The high-strength lightweight concrete insulation wall block according to claim 1, characterized in that: The lightweight ceramsite was sieved through a 5mm sieve and then soaked in deionized water for 24 hours, with the water changed every 8 hours. After soaking, it was dried at 105℃ to constant weight. The expanded perlite was sieved through a 2mm sieve and then mixed with a 3% (w / w) ethanol solution of silane coupling agent KH-550. The mixture was stirred at 60℃ for 1 hour, filtered, and then dried at 105℃ for 2 hours.

3. The high-strength lightweight concrete insulation wall block according to claim 1, characterized in that: The glass fiber is alkali-resistant and 15 mm in length. It is soaked in a 5% hydrochloric acid solution for 30 minutes, then washed with deionized water until neutral, and then dried at 60°C for 1 hour.

4. The high-strength lightweight concrete insulation wall block according to claim 1, characterized in that: The preparation method of the graphene-modified polystyrene particles includes the following steps: Polystyrene particles were placed in a 5% ethanol solution and ultrasonically cleaned for 30 minutes to remove surface impurities. After drying, a 5% graphene dispersion with a graphene content of 2 wt% was added, and the mixture was mechanically stirred for 60 minutes. Then, silane coupling agent KH550 was added at a rate of 2% of the mass of the polystyrene particles, and the mixture was reacted in a water bath at 60°C for 3 hours. After the reaction was completed, the mixture was filtered and dried to obtain graphene-modified polystyrene particles.

5. A high-strength lightweight concrete insulation wall block according to claim 1, characterized in that: The preparation method of the water-reducing agent includes the following steps: Pour acrylic acid, polyethylene glycol methacrylate, sodium allyl sulfonate and deionized water into a four-necked flask and stir well. Then dissolve ammonium persulfate in deionized water to prepare an initiator solution. Place the flask in a 65°C water bath and set the stirring speed to 300 r / min. Then, add 1 / 3 of the initiator solution and react for 10 minutes. Then, start adding the remaining initiator solution and the remaining monomer mixture dropwise at a rate of 2 mL / min for 2 hours. After the addition is complete, raise the temperature to 75°C, keep the reaction at this temperature for 1.5 hours, and then cool it to 40°C. Adjust the pH to 7 with a 30% sodium hydroxide solution to obtain the water-reducing agent.

6. The high-strength lightweight concrete insulation wall block according to claim 1, characterized in that: The method for preparing the air-entraining agent includes the following steps: After rosin is crushed to a particle size of 2 mm, it is put into a reaction vessel equipped with a stirrer, a 30% sodium hydroxide solution is added, the temperature is raised to 80°C, and then the saponification reaction is carried out by stirring at 300 r / min for 1 h. After the reaction was completed, the temperature was lowered to 60°C, and a 37% formaldehyde solution was slowly added dropwise over 30 minutes. After the addition was complete, the temperature was raised to 90°C and the reaction was continued for 2 hours. Then, sodium dodecylbenzenesulfonate was added and stirred for 30 minutes. Triethanolamine was then added, and the reaction was maintained at 60°C for 1 hour. Finally, the mixture was cooled to room temperature, diluted with deionized water, and the pH was adjusted to 9 to obtain the air-entraining agent.

7. A high-strength lightweight concrete insulation wall block according to claim 1, characterized in that: The preparation method of the nano-calcium carbonate includes the following steps: Limestone was crushed to a particle size of 50 mm and calcined at 1000℃ for 2 hours to produce quicklime. The quicklime was added to hot water at 80℃ at a solid-liquid ratio of 1:

8. After 30 minutes, impurities were removed by sieving to obtain a calcium hydroxide suspension with a concentration of 1.2 mol / L. The suspension was cooled to 25°C, and a mixed gas containing 20% ​​CO2 was introduced. The ratio of CO2 to N2 was 1:4, and the gas flow rate was set to 0.5 m³ / min. 3 / h, while adding 0.5% by mass of sucrose as a crystal form control agent, and maintaining a stirring speed of 300 r / min during the reaction; When the pH dropped to 7.5, the aeration was stopped, and 1% stearic acid was added. The mixture was stirred at 60°C for 30 minutes to modify the surface. The reaction product was then filtered, dried at 80°C, and pulverized by air jet to obtain nano-calcium carbonate with an average particle size of 50 nm.

8. A high-strength lightweight concrete insulation wall block according to claim 1, characterized in that: The method for preparing the silicate cement includes the following steps: Limestone, clay, and iron ore powder were mixed in a mass ratio of 85:12:3, crushed to a particle size of 5 mm, and fed into a raw meal mill. Water was added and the mixture was ground to a particle size of 80 μm to obtain a raw meal slurry. The slurry was spray-dried and then fed into a rotary kiln, where it was heated to 1450°C at a rate of 5°C / min and calcined for 30 minutes to produce clinker. After cooling to room temperature, the clinker was mixed with 5% dihydrate gypsum and ground in a cement mill to a specific surface area of ​​350 m² / g. 2 / kg, and then sieved to obtain silicate cement.

9. A method for preparing a high-strength lightweight concrete insulated wall block, applicable to the high-strength lightweight concrete insulated wall block described in any one of claims 1-8, characterized in that: The preparation method includes the following steps: S1. According to the formula, take silicate cement, fly ash, silica fume and nano calcium carbonate and pour them into the mixer. Set the mixing speed to 300 r / min and dry mix for 5 minutes. During this period, scrape off the residual material on the inner wall of the mixer with a scraper every 1 minute to finally obtain the mixed cementitious material. S2. Soak the lightweight ceramsite in deionized water for 24 hours, changing the water every 8 hours. After soaking, drain the ceramsite with a filter until there is no free water on the surface. Take the treated lightweight ceramsite, expanded perlite, and graphene-modified polystyrene particles, pour them into a mixer, set the speed to 120 r / min, and stir for 3 minutes. Take a sample to observe the uniformity of the mixture, ensuring that there is no obvious stratification of the three aggregates, and obtain a lightweight aggregate mixture.

10. The method for preparing a high-strength lightweight concrete thermal insulation wall block according to claim 9, characterized in that: The preparation method further includes the following steps: S3. Pour the mixture of cementitious material and lightweight aggregate into the mixer, add glass fiber according to the formula, set the speed to 150 r / min and dry mix for 3 minutes. Then dissolve the water-reducing agent and air-entraining agent in water to make a solution, pour it into the mixer, adjust the speed to 200 r / min and wet mix for 5 minutes, and stir until the slurry is in a uniform flow state. S4. Pour the slurry into a steel mold, place it on a vibrating table and vibrate at a frequency of 50Hz and an amplitude of 0.5mm for 1 minute. Scrape the surface of the mold with a scraper and cover it with a plastic film. Let it stand in a 20℃ environment for 24 hours. After demolding, number the blocks and place them in a standard curing room. Maintain the temperature at 20℃ and spray the surface with water 3 times a day to keep it moist. Take them out after curing for 28 days.

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