Anti-crack foam concrete as well as preparation method and application thereof

Abstract

The invention provides anti-crack foam concrete as well as a preparation method and application thereof, and belongs to the technical field of building materials. The added quick lime can generate a certain micro-expansion effect when encountering water, shrinkage of the material caused by hydration can be compensated to a certain extent, an alkaline environment can be provided for the foaming agent, and smooth foaming is guaranteed; the magnesite tailing powder is added, so that dicalcium silicate, tricalcium silicate and periclase crystal phases with relatively high fire resistance can be obtained when a fire disaster occurs; the phosphogypsum is added as an activator of the coal gasification slag, so that the hydration induction period is shortened, the later strength development is promoted, and the crack resistance of the foam concrete is improved; the modified fibers are added, the fibers form an irregular supporting structure in the multi-bubble slurry to play a role in protecting the foam, meanwhile, the fibers can improve the pore structure and also have an effect of hindering microcrack propagation, and the three fibers have a synergistic effect, so that the crack resistance of the foam concrete is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a crack-resistant foam concrete and a preparation method and application thereof. Background Art

[0002] Foamed concrete is an inorganic thermal insulation material with excellent performance. Compared with ordinary concrete, it has low dry density and low thermal conductivity, good fluidity, light weight, good thermal insulation performance, etc. It is mainly prepared from cement binder, foaming agent, foam stabilizer and water. However, the foamed concrete in the prior art will shrink after pouring, which will cause the foamed concrete to crack, affecting its use effect. At the same time, its low strength also limits its application to a certain extent.

[0003] Therefore, there is an urgent need for a foamed concrete with low shrinkage and high strength. Summary of the invention

[0004] The purpose of the present invention is to provide a crack-resistant foam concrete and a preparation method and application thereof. The foam concrete provided by the present invention has a low shrinkage rate, good crack-resistant effect and high strength.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides a crack-resistant foam concrete, comprising component A, component B and component C; in terms of weight, the component A comprises 350-400 parts of cement, 110-150 parts of quicklime, 140-170 parts of fly ash, 65-70 parts of magnesite tailing powder, 80-160 parts of phosphogypsum, 80-100 parts of coal gasification slag, 1050-1200 parts of water and 10-12 parts of a coagulant;

[0007] The B component includes 2 to 5 parts of a foaming agent, 20 to 50 parts of a foam stabilizer and 450 to 550 parts of water;

[0008] The C component includes 2 to 5 parts of modified fibers; the fibers in the modified fibers include basalt fibers, polyvinyl alcohol fibers and polypropylene fibers; the modified fibers are prepared from fibers, buffers, organic solvents, silane coupling agents and surfactants.

[0009] Preferably, the mass ratio of the basalt fiber, the polyvinyl alcohol fiber and the polypropylene fiber is (2-3):(1-2):3.

[0010] Preferably, the cement comprises silicate cement and sulphoaluminate cement.

[0011] Preferably, the particle size of the quicklime is 30-80 μm.

[0012] Preferably, the particle size of the fly ash is 5 - 10 μm.

[0013] Preferably, the particle size of the magnesite tailings powder is 10 - 35 μm.

[0014] Preferably, the particle size of the phosphogypsum is 5 - 10 μm.

[0015] Preferably, the foaming agent includes one or more of lauramidopropyl hydroxysultaine, α-olefin sulfonate, octylphenol polyoxyethylene ether, sodium dodecyl ether sulfate, and sodium dodecyl sulfate; the foam stabilizer includes one of gum arabic powder, alkylolamide, and calcium stearate.

[0016] The present invention also provides a method for preparing the crack-resistant foam concrete described in the above technical solution, comprising the following steps:

[0017] (1) Mix component A and component C to obtain a mixed slurry.

[0018] (2) Mix the foaming agent, water, and foam stabilizer in component B, then foam to obtain foam.

[0019] (3) Mix the mixed slurry obtained in step (1) and the foam obtained in step (2), and after solidification, cure to obtain the crack-resistant foam concrete.

[0020] There is no sequence requirement for steps (1) and (2).

[0021] The present invention also provides the application of the crack-resistant foam concrete described in the above technical solution or the crack-resistant foam concrete prepared according to the preparation method described in the above technical solution in the construction field.

[0022] The present invention provides a crack-resistant foamed concrete, which comprises component A, component B and component C; by weight, component A includes 350-400 parts of cement, 110-150 parts of quicklime, 140-170 parts of fly ash, 65-70 parts of magnesite tailing powder, 80-160 parts of phosphogypsum, 80-100 parts of coal gasification slag, 1050-1200 parts of water and 10-12 parts of coagulant; component B includes 2-5 parts of foaming agent, 20-50 parts of foam stabilizer and 450-550 parts of water; component C includes 2-5 parts of modified fiber; the fibers in the modified fiber include basalt fiber, polyvinyl alcohol fiber and polypropylene fiber; the modified fiber is prepared from fiber, buffer, organic solvent, silane coupling agent and surfactant. The quicklime added in the present invention will produce a certain micro-expansion effect when encountering water, which can compensate the shrinkage caused by hydration to a certain extent, and can provide an alkaline environment for the foaming agent to ensure the smooth progress of foaming; adding magnesite tailing powder can obtain high-fire-resistant dicalcium silicate, tricalcium silicate and periclase crystal phases in case of fire; adding phosphogypsum as an activator for coal gasification slag can shorten the hydration induction period, promote the later strength development and improve the crack resistance of the foamed concrete; adding modified fiber, the fibers form an irregular support structure in the multi-bubble slurry to play a role in protecting the foam, so that less foam breaks during the preparation process, reducing the density of the foamed concrete. At the same time, the fiber can improve the pore structure, the pore diameter decreases and the pore shape becomes more round, and it also has the effect of hindering the expansion of microcracks. There is a synergistic effect among the three fibers to improve the crack resistance of the foamed concrete. The results of the examples show that the dry shrinkage value of the foamed concrete provided by the present invention is below 0.97 mm / m, the tensile strength is above 97 kPa, and the compressive strength is above 3.86 MPa. Detailed Embodiments

[0023] The present invention provides a crack-resistant foamed concrete, which comprises component A, component B and component C; by weight, component A includes 350-400 parts of cement, 110-150 parts of quicklime, 140-170 parts of fly ash, 65-70 parts of magnesite tailing powder, 80-160 parts of phosphogypsum, 80-100 parts of coal gasification slag, 1050-1200 parts of water and 10-12 parts of coagulant;

[0024] Component B includes 2-5 parts of foaming agent, 20-50 parts of foam stabilizer and 450-550 parts of water;

[0025] Component C includes 2-5 parts of modified fiber; the fibers in the modified fiber include basalt fiber, polyvinyl alcohol fiber and polypropylene fiber; the modified fiber is prepared from fiber, buffer, organic solvent, silane coupling agent and surfactant.

[0026] Unless otherwise specified, the present invention does not have special limitations on the sources of each component, and commercially available products well-known to those skilled in the art can be used.

[0027] The crack-resistant foamed concrete provided by the present invention includes component A.

[0028] Calculated by weight parts, the component A includes 350 - 400 parts of cement. In the embodiments of the present invention, the dosage of the cement can specifically be 350 parts, 360 parts, 370 parts, 380 parts, 390 parts or 400 parts.

[0029] In the present invention, the cement preferably includes portland cement and sulfoaluminate cement.

[0030] In the present invention, the portland cement is preferably ordinary portland cement of grade 42.5.

[0031] In the present invention, the sulfoaluminate cement is preferably sulfoaluminate cement of grade 42.5.

[0032] In the present invention, the mass ratio of the portland cement to the sulfoaluminate cement is preferably (1 - 3):1, more preferably 2:1. The present invention uses the high strength of the portland cement and the rapid hardening of the sulfoaluminate cement to ensure the stability of the bubbles generated by the foaming agent, minimize the loss rate of the bubbles to the greatest extent, and thus improve the performance of the foamed concrete.

[0033] Calculated based on the dosage of the cement being 350 - 400 parts, the component A includes 110 - 150 parts of quicklime. In the embodiments of the present invention, the dosage of the quicklime can specifically be 110 parts, 120 parts, 130 parts, 140 parts or 150 parts. In the present invention, the quicklime will produce a certain micro-expansion effect when encountering water, which can, to a certain extent, supplement the shrinkage caused by hydration of the material, and can provide an alkaline environment for the foaming agent to ensure the smooth progress of foaming.

[0034] In the present invention, the mass content of calcium oxide in the quicklime is preferably 75 - 85%, more preferably 80%.

[0035] In the present invention, the particle size of the quicklime is preferably 30 - 80 μm. By controlling the dosage, particle size and other parameters of the quicklime within the above ranges, the shrinkage rate of the foamed concrete can be further reduced.

[0036] Calculated based on the dosage of the cement being 350 - 400 parts, the component A includes 140 - 170 parts of fly ash. In the embodiments of the present invention, the dosage of the fly ash can specifically be 140 parts, 150 parts, 160 parts or 170 parts.

[0037] In the present invention, the fly ash is preferably class-I fly ash or class-II fly ash from coal-fired power plants, and more preferably class-II fly ash from coal-fired power plants.

[0038] In the present invention, the particle size of the fly ash is preferably 5 - 10 μm. By controlling the dosage, particle size, etc. of the fly ash within the above ranges, the properties of the foamed concrete can be further improved.

[0039] Based on the cement dosage of 350 - 400 parts, the component A includes 65 - 70 parts of magnesite tailing powder. In the embodiments of the present invention, the dosage of the magnesite tailing powder can specifically be 65 parts, 66 parts, 67 parts, 68 parts, 69 parts or 70 parts.

[0040] In the present invention, the particle size of the magnesite tailing powder is preferably 10 - 35 μm.

[0041] The present invention has no special limitation on the source of the magnesite tailing powder, and the magnesite tailing powder from sources well-known to those skilled in the art can be used. In the embodiments of the present invention, the chemical composition and the mass percentage content of each component of the magnesite tailing powder can specifically be: magnesium oxide 40.82%, silicon dioxide 17.52%, calcium oxide 1.68%, aluminum oxide 0.54% and iron oxide 0.43%; the loss on ignition (LOI) of the magnesite tailing powder is 39.01%; the M / S (mass ratio of magnesium to silicon) of the magnesite tailing powder is 2.33.

[0042] In the present invention, the C / S (mass ratio of calcium to silicon) of the component A is preferably 2 - 3. By adding quicklime and magnesite tailing powder in the present invention to make the C / S of the component A within the above ranges, calcium silicate, tricalcium silicate and periclase crystal phases with higher fire resistance can be formed during a fire. By controlling parameters such as the dosage of the magnesite tailing powder within the above ranges in the present invention, the properties of the foamed concrete can be further improved.

[0043] Based on the cement dosage of 350 - 400 parts, the component A includes 80 - 160 parts of phosphogypsum. In the embodiments of the present invention, the dosage of the phosphogypsum can specifically be 80 parts, 90 parts, 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts or 160 parts.

[0044] In the present invention, the particle size of the phosphogypsum is preferably 5 - 10 μm. In the present invention, the phosphogypsum is used as an activator for coal gasification slag. By controlling the dosage of the phosphogypsum within the above ranges in the present invention, a better activation effect can be achieved.

[0045] Based on the cement dosage of 350 - 400 parts, the component A includes 80 - 100 parts of coal gasification slag. In the embodiments of the present invention, the dosage of the coal gasification slag can specifically be 80 parts, 85 parts, 90 parts, 95 parts or 100 parts.

[0046] In the present invention, the particle size of the coal gasification slag is preferably 5 - 6 μm. In the present invention, after the coal gasification slag is activated by phosphogypsum, it can shorten the hydration induction period and accelerate the appearance of the second exothermic peak, thereby promoting the later strength development and improving the crack resistance of the foamed concrete.

[0047] The present invention has no special limitation on the source of the coal gasification slag, and the coal gasification slag from sources well-known to those skilled in the art can be used. In the embodiments of the present invention, the chemical composition and the mass content of each component of the coal gasification slag can specifically be: silicon dioxide 29.53%, calcium oxide 22.36%, aluminum oxide 17.55%, magnesium oxide 10.12%, sodium oxide 6.75%, iron oxide 2.25%, titanium dioxide 2.01%, sulfur trioxide 1.54% and potassium oxide 0.58%; the loss on ignition (LOI) of the coal gasification slag is 7.31%.

[0048] Based on the cement dosage of 350 - 400 parts, the component A includes 1050 - 1200 parts of water. In the embodiments of the present invention, the dosage of the water can specifically be 1050 parts, 1080 parts, 1100 parts, 1150 parts or 1200 parts. By controlling the water dosage within the above range, the present invention can have an appropriate water-binder ratio and further improve the various properties of the foamed concrete.

[0049] Based on the cement dosage of 350 - 400 parts, the component A includes 10 - 12 parts of coagulant. In the embodiments of the present invention, the dosage of the coagulant can specifically be 10 parts, 11 parts or 12 parts. In the present invention, the coagulant can accelerate the setting of the concrete and reduce the foam breakage rate when the slurry starts to set.

[0050] In the present invention, the coagulant preferably includes sodium chloride and triethanolamine; the mass ratio of sodium chloride to triethanolamine is preferably 1:(3 - 5), more preferably 1:4. By controlling the dosage and type of the accelerator within the above range, the present invention can further improve the various properties of the foamed concrete.

[0051] The crack-resistant foamed concrete provided by the present invention includes component B.

[0052] Based on the cement dosage of 350 - 400 parts in component A, the component B includes 2 - 5 parts of foaming agent. In the embodiments of the present invention, the dosage of the foaming agent can specifically be 2 parts, 3 parts, 4 parts or 5 parts.

[0053] In the present invention, the foaming agent preferably comprises one or more of lauramidopropyl hydroxysultaine, sodium α-olefin sulfonate, octylphenol polyoxyethylene ether, sodium dodecyl ether sulfate and sodium dodecyl sulfate, and more preferably sodium dodecyl sulfate.

[0054] Based on the amount of cement in component A being 350 to 400 parts, component B comprises 20 to 50 parts of foam stabilizer. In the embodiments of the present invention, the amount of the foam stabilizer can specifically be 20 parts, 30 parts, 40 parts or 50 parts.

[0055] In the present invention, the foam stabilizer preferably comprises one of gum arabic powder, alkylolamide and calcium stearate, and more preferably calcium stearate.

[0056] Based on the amount of cement in component A being 350 to 400 parts, component B comprises 450 to 550 parts of water. In the embodiments of the present invention, the amount of the water can specifically be 450 parts, 460 parts, 470 parts, 480 parts, 490 parts, 500 parts, 510 parts, 520 parts, 530 parts, 540 parts or 550 parts.

[0057] By controlling the amounts of the foaming agent, foam stabilizer and water within the above ranges in the present invention, good foaming and foam stabilizing effects can be achieved, and the various properties of the foam concrete can be further improved.

[0058] The crack-resistant foam concrete provided by the present invention further comprises component C.

[0059] Based on the amount of cement in component A being 350 to 400 parts, component C comprises 2 to 5 parts of modified fiber. In the embodiments of the present invention, the amount of the modified fiber can specifically be 2 parts, 3 parts, 4 parts or 5 parts.

[0060] In the present invention, the fibers in the modified fiber include basalt fiber, polyvinyl alcohol fiber and polypropylene fiber.

[0061] In the present invention, the length of the basalt fiber is preferably 6 to 8 mm; the diameter of the basalt fiber is preferably 0.01 to 0.02 mm, and more preferably 0.015 mm.

[0062] In the present invention, the length of the polyvinyl alcohol fiber is preferably 9 to 10 mm; the diameter of the polyvinyl alcohol fiber is preferably 0.02 to 0.06 mm, and more preferably 0.04 mm.

[0063] In the present invention, the length of the polypropylene fiber is preferably 12 to 13 mm; the diameter of the polypropylene fiber is preferably 0.02 to 0.04 mm, more preferably 0.03 mm. The present invention does not have special limitations on the source of the fiber, and commercially available products well-known to those skilled in the art can be used. In the examples of the present invention, the density of the basalt fiber is 2.6 g / mm 3 , the tensile strength is 4000 MPa, and the elastic modulus is 80 GPa; the density of the polyvinyl alcohol fiber is 1.3 g / mm 3 , the tensile strength is 1600 MPa, and the elastic modulus is 40 GPa; the density of the polypropylene fiber is 0.9 g / mm 3 , the tensile strength is 420 MPa, and the elastic modulus is 5 GPa.

[0064] In the present invention, the mass ratio of the basalt fiber, polyvinyl alcohol fiber and polypropylene fiber is preferably (2 to 3):(1 to 2):3. In the present invention, the fibers form an irregular support structure in the multi-bubble slurry to protect the foam, so that fewer foams break during the preparation process, reducing the density of the foam concrete. At the same time, the fibers can improve the pore structure, the pore diameter decreases and the pore shape becomes more round, and they also have the effect of hindering the propagation of microcracks. In addition, there is a synergistic effect among the three fibers, improving the crack resistance of the foam concrete.

[0065] In the present invention, the modified fiber is prepared from a fiber, a buffer, an organic solvent, a silane coupling agent and a surfactant.

[0066] In the present invention, the buffer is preferably ammonium bicarbonate.

[0067] In the present invention, the organic solvent is preferably absolute ethanol.

[0068] In the present invention, the mass ratio of the fiber, buffer and organic solvent is preferably 1:(2 to 2.5):(1.8 to 2.2), more preferably 1:2.3:2.

[0069] In the present invention, the silane coupling agent preferably includes at least one of KH550, KH560 and KH570.

[0070] In the present invention, the surfactant is preferably alkylphenol polyoxyethylene ether emulsion OP-10.

[0071] In the present invention, the mass ratio of the silane coupling agent and the surfactant is preferably 1:(0.5 to 1.5), more preferably 1:1.

[0072] In the present invention, the total mass of the silane coupling agent and the surfactant is preferably 45-50% of the mass of the fiber, more preferably 48%. By controlling the amounts of the respective components within the above ranges in the present invention, a better modification effect on the fiber can be achieved, fiber sedimentation can be avoided, and the various properties of the foamed concrete can be further improved.

[0073] In the present invention, the preparation method of the modified fiber is preferably as follows: basalt fiber, polyvinyl alcohol fiber and polypropylene fiber are mixed to obtain a mixed fiber; the mixed fiber, the buffer agent and the organic solvent are mixed, and then a silane coupling agent and a surfactant are added, and after standing for 1-10 min, drying is carried out to obtain the modified fiber.

[0074] The present invention has no special limitation on the operation of the drying, and the drying technical solutions well-known to those skilled in the art can be adopted.

[0075] The present invention also provides a preparation method of the crack-resistant foamed concrete described in the above technical solution, including the following steps:

[0076] (1) Component A and component C are mixed to obtain a mixed slurry;

[0077] (2) The foaming agent, water and foam stabilizer in component B are mixed and then foamed to obtain foam;

[0078] (3) The mixed slurry obtained in step (1) and the foam obtained in step (2) are mixed, and after solidification, curing is carried out to obtain the crack-resistant foamed concrete;

[0079] There is no sequence requirement for steps (1) and (2).

[0080] In the present invention, component A and component C are mixed to obtain a mixed slurry.

[0081] In the present invention, the mixing of component A and component C is preferably as follows: component A and component C are mixed, stirred at 150-200 rpm for 0.5-5 min, and then left standing for 1-10 min to obtain a mixed slurry; more preferably: component A and component C are mixed, stirred at 180 rpm for 1 min, and then left standing for 5 min to obtain a mixed slurry.

[0082] In the present invention, the foaming agent, water and foam stabilizer in component B are mixed and then foamed to obtain foam.

[0083] In the present invention, the mixing of the foaming agent, water and foam stabilizer is preferably as follows: mix the foaming agent and water, stir at 200 - 400 rpm for 5 - 15 min, then add the foam stabilizer and stir at 200 - 400 rpm for 5 - 15 min; more preferably: mix the foaming agent and water, stir at 300 rpm for 10 min, then add the foam stabilizer and stir at 300 rpm for 10 min.

[0084] In the present invention, the foaming is preferably carried out using a compressed air foaming machine; the foaming amount is preferably 50 - 70 L / min, more preferably 60 L / min; the air pressure is 0.3 - 0.6 MPa, more preferably 0.5 MPa; the compression frequency is preferably 50 - 70 Hz, more preferably 60 Hz; the foaming time is preferably 5 - 15 s, more preferably 10 s.

[0085] After obtaining the mixed slurry and foam, the present invention mixes the mixed slurry and the foam, solidifies and then cures to obtain crack-resistant foam concrete.

[0086] In the present invention, the mixing of the mixed slurry and foam is preferably carried out under stirring conditions; the stirring rate is preferably 150 - 200 rpm, more preferably 180 rpm; the stirring time is preferably 1 - 10 min, more preferably 5 min.

[0087] After mixing is completed, the present invention preferably pours the mixture obtained from the mixing into a mold, covers it with a plastic film, and then solidifies it.

[0088] The present invention has no special limitation on the size of the mold, and it can be selected according to actual needs.

[0089] The present invention has no special limitation on the source and type of the plastic film, and commercially available products well-known to those skilled in the art can be used.

[0090] In the present invention, the solidification temperature is preferably room temperature; the solidification time is preferably 20 - 25 h, more preferably 24 h.

[0091] After solidification is completed, the present invention preferably demolds the solidified product and then cures it.

[0092] The present invention has no special limitation on the demolding operation, and technical solutions well-known to those skilled in the art can be used.

[0093] In the present invention, the curing temperature is preferably 80 - 100 °C, more preferably 90 °C; the curing time is preferably 1 - 3 days, more preferably 2 days; the curing is preferably carried out in a steam chamber; the humidity of the steam chamber is preferably 90% - 100%, more preferably 95%.

[0094] By controlling the preparation method and parameters within the above ranges, the present invention can further improve the various properties of foamed concrete.

[0095] The present invention also provides the application of the crack-resistant foamed concrete described in the above technical solution or the crack-resistant foamed concrete prepared according to the preparation method described in the above technical solution in the construction field.

[0096] The present invention has no special limitation on the operation of the above application, and the technical solutions of the application well-known to those skilled in the art can be adopted.

[0097] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0098] The chemical compositions and mass contents of magnesite tailings powder in the examples and comparative examples are shown in Table 1.

[0099] Table 1 Chemical Compositions and Mass Contents of Magnesite Tailings Powder

[0100] M / S MgO <![CDATA[SiO 2 > CaO <![CDATA[Al 2 O 3 > <![CDATA[Fe 2 O 3 > LOI 2.33 40.82％ 17.52％ 1.68％ 0.54％ 0.43％ 39.01％

[0101] The chemical compositions and mass contents of coal gasification slag in the examples and comparative examples are shown in Table 2.

[0102] Table 2 Chemical Compositions and Mass Contents of Coal Gasification Slag

[0103] <![CDATA[SiO 2 > CaO <![CDATA[Al 2 O 3 > MgO <![CDATA[Sodium 2 O]]> <![CDATA[Fe 2 O 3 > <![CDATA[TiO 2 > <![CDATA[SO 3 > <![CDATA[K 2 O]]> LOI 29.53％ 22.36％ 17.55％ 10.12％ 6.75％ 2.25％ 2.01％ 1.54％ 0.58％ 7.31％

[0104] Example 1

[0105] A kind of crack-resistant foamed concrete is composed of component A, component B and component C; by weight, component A consists of 394 parts of cement (ordinary Portland cement of grade 42.5 and sulphoaluminate cement of grade 42.5 with a mass ratio of 2:1), 111 parts of quicklime (calcium oxide mass content 80%, particle size 30 - 80 μm), 159 parts of fly ash (class II fly ash from coal power plants, particle size 5 - 10 μm), 65 parts of magnesite tailings powder (particle size 10 - 35 μm), 135 parts of phosphogypsum (particle size 5 - 10 μm), 90 parts of coal gasification slag (particle size 5 - 6 μm), 1134 parts of water and 11 parts of coagulant promoter (sodium chloride and triethanolamine with a mass ratio of 1:4);

[0106] Component B consists of 4 parts of foaming agent (sodium dodecyl sulfate), 22 parts of foam stabilizer (calcium stearate) and 471 parts of water;

[0107] The component C is 3 parts of modified fiber; the fiber in the modified fiber is composed of basalt fiber (length 6 - 8 mm, diameter 0.015 mm), polyvinyl alcohol fiber (length 9 - 10 mm, diameter 0.04 mm) and polypropylene fiber (length 12 - 13 mm, diameter 0.03 mm); the modified fiber is prepared from fiber, buffer (ammonium bicarbonate), organic solvent (absolute ethanol), silane coupling agent (KH550) and surfactant (alkylphenol polyoxyethylene ether emulsion OP - 10); the mass ratio of fiber, buffer and organic solvent is 1:2.3:2, the mass ratio of silane coupling agent and surfactant is 1:1, and the total mass of silane coupling agent and surfactant is 48% of the mass of fiber;

[0108] The preparation method of the modified fiber is as follows: mix basalt fiber, polyvinyl alcohol fiber and polypropylene fiber to obtain mixed fiber, mix the mixed fiber with buffer and organic solvent, then add silane coupling agent and surfactant, let it stand for 5 min and then dry to obtain modified fiber;

[0109] The preparation method of the crack - resistant foamed concrete is as follows: (1) Mix component A and component C, stir at 180 rpm for 1 min, then let it stand for 5 min to obtain a mixed slurry;

[0110] (2) Mix the foaming agent and water in component B, stir at 300 rpm for 10 min, then add the foam stabilizer and stir at 300 rpm for 10 min, and use a compressed air foaming machine to foam; the foaming amount is 60 L / min; the air pressure is 0.5 MPa; the compression frequency is 60 Hz; the foaming time is 10 s to obtain foam;

[0111] (3) Stir - mix the mixed slurry and the foam at 180 rpm for 5 min, pour it into a mold, cover it with a plastic film, uncover the film after solidifying at room temperature for 24 h, and cure it in a steam chamber at 90℃ (humidity 95%) for 2 days to obtain crack - resistant foamed concrete.

[0112] Examples 2 - 8, Comparative Examples 1 - 8

[0113] The differences between Examples 2 - 8 and Comparative Examples 1 - 8 and Example 1 are only the dosages of each component, and other parameters and preparation methods are the same as those of Example 1.

[0114] The compositions and dosages of each component of the foamed concrete in Examples 1 - 8 and Comparative Examples 1 - 8 are shown in Table 3.

[0115] Table 3 Compositions and dosages of each component of the foamed concrete in Examples 1 - 8 and Comparative Examples 1 - 8

[0116]

[0117]

[0118] Test the dry density, compressive strength, tensile strength, thermal conductivity, combustion performance grade and drying shrinkage value of the foamed concrete in Test Examples 1 to 8 and Comparative Examples 1 to 8. The test standards for each parameter are as follows: Dry density: "Foamed Concrete" JG / T 266; Compressive strength: "Foamed Concrete" JG / T 266; Tensile strength: "Elastomeric Polystyrene Granule Thermal Insulation Materials for External Thermal Insulation Systems of External Walls" JG / T 158-2013; Thermal conductivity: "Determination of Steady-State Thermal Resistance and Related Characteristics of Thermal Insulation Materials - Guarded-Hot-Plate Method" GB / T 10294; Combustion performance grade: "Code for Fire Protection Design of Buildings" GB 50016-2014; Drying shrinkage value: "Test Methods for Properties of Autoclaved Aerated Concrete" GB / T 10969. The results are shown in Table 4.

[0119] Table 4 Dry density, compressive strength, thermal conductivity, drying shrinkage value of the foamed concrete in Examples 1 to 8 and Comparative Examples 1 to 8

[0120]

[0121]

[0122] It can be seen from the data in Table 4 that the drying shrinkage value of the crack-resistant foamed concrete provided by the present invention is smaller, the strength is higher, and there is a synergistic effect among the three kinds of fibers, which can further improve the various properties of the foamed concrete.

[0123] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A crack-resistant foamed concrete, comprising component A, component B and component C; in parts by weight, the component A comprises 350-400 parts of cement, 110-150 parts of quicklime, 140-170 parts of fly ash, 65-70 parts of magnesite tailings powder, 80-160 parts of phosphogypsum, 80-100 parts of coal gasification slag, 1050-1200 parts of water and 10-12 parts of accelerator; The B component includes 2 to 5 parts of a foaming agent, 20 to 50 parts of a foam stabilizer and 450 to 550 parts of water; The C component includes 2 to 5 parts of modified fibers; the fibers in the modified fibers include basalt fibers, polyvinyl alcohol fibers and polypropylene fibers; the modified fibers are prepared from fibers, buffers, organic solvents, silane coupling agents and surfactants.

2. The crack-resistant foamed concrete according to claim 1, characterized in that: The mass ratio of the basalt fiber, the polyvinyl alcohol fiber and the polypropylene fiber is (2-3): (1-2):

3.

3. The crack-resistant foamed concrete according to claim 1, characterized in that: The cement includes silicate cement and sulphoaluminate cement.

4. The crack-resistant foamed concrete according to claim 1, characterized in that: The particle size of the quicklime is 30 to 80 μm.

5. The crack-resistant foamed concrete according to claim 1, characterized in that: The particle size of the fly ash is 5 to 10 μm.

6. The crack-resistant foamed concrete according to claim 1, characterized in that: The particle size of the magnesite tailings powder is 10 to 35 μm.

7. The crack-resistant foamed concrete according to claim 1, characterized in that: The particle size of the phosphogypsum is 5 to 10 μm.

8. The crack-resistant foamed concrete according to claim 1, characterized in that: The foaming agent includes one or more of lauryl amide propyl hydroxysulfobetaine, sodium α-olefin sulfonate, octylphenyl polyoxyethylene ether, sodium dodecyl ether sulfate and sodium dodecyl sulfate; the foam stabilizer includes one of gum arabic powder, alkyl alcohol amide and calcium stearate.

9. The method for preparing the crack-resistant foamed concrete according to any one of claims 1 to 8, comprising the following steps: (1) mixing component A and component C to obtain a mixed slurry; (2) mixing the blowing agent, water and foam stabilizer in component B and foaming to obtain foam; (3) mixing the mixed slurry obtained in step (1) and the foam obtained in step (2), and solidifying the mixed slurry after solidification to obtain crack-resistant foamed concrete; There is no order of precedence for steps (1) and (2).

10. Use of the crack-resistant foamed concrete according to any one of claims 1 to 8 or the crack-resistant foamed concrete prepared by the preparation method according to claim 9 in the field of construction.

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