SiO2 / aramid composite modified high-strength foam concrete and preparation method thereof

Abstract

The application provides a SiO2 / aramid composite modified high-strength foam concrete, the high-strength foam concrete comprises the following components in parts by weight: natural broken stone 500-800 parts, river sand 400-550 parts, cement 300-360 parts, fly ash 80-100 parts, foaming agent 3-6 parts, SiO2 / aramid composite reticular cloth 15-30 parts and water 180-200 parts; wherein the SiO2 / aramid composite reticular cloth is a SiO2 nanofiber film loaded on two sides of aramid fiber cloth, and the SiO2 / aramid composite reticular cloth is selected to have an area of 1cm 2 -10cm 2 . The application adds the SiO2 / aramid composite reticular cloth into the foam concrete, improves the compressive strength of the concrete, and obtains a high-strength concrete.

Description

TECHNICAL FIELD

[0001] The application relates to the field of building materials, in particular to SiO2 / aramid composite modified high-strength foam concrete and a preparation method thereof. BACKGROUND

[0002] With the development of buildings to high-rise and super high-rise, reducing the self weight of walls has become the goal pursued by many builders, meanwhile, the requirements of building energy saving and building environmental protection make some light concrete become the focus of development and research, and in recent years, foam concrete has attracted much attention and research.

[0003] The foam concrete has the characteristics of small bulk density, excellent heat preservation, heat insulation, fire resistance, sound insulation and earthquake resistance, and can be factory-produced into various shapes of prefabricated products or cast on site, and has a wide application prospect in various buildings, especially building energy saving.

[0004] The foam concrete refers to light concrete formed by introducing a proper amount of small bubbles into cement paste or cement mortar, stirring uniformly and then pouring and hardening, and is an environment-friendly wall material with heat preservation, fire prevention and good economic benefits. The traditional foam concrete has very low strength (only 1-10 MPa), and can only be used in some filling engineering and cannot meet the requirements of structural engineering. In recent years, some studies on high-strength foam concrete prepared by using low water-binder ratio and replacing sand with micro-silica fume and fly ash have appeared, for example, foam concrete with a compressive strength of 60 MPa is prepared under special curing conditions. Although there are a large number of research reports on the related properties and preparation process of foam concrete, there are few research reports on high-strength foam concrete. SUMMARY

[0005] The technical problem to be solved is to provide SiO2 / aramid composite modified high-strength foam concrete, which adds SiO2 / aramid composite mesh cloth in the foam concrete, improves the compressive strength of the concrete, and obtains high-strength concrete.

[0006] Technical scheme: The SiO2 / aramid composite modified high-strength foam concrete comprises the following components in parts by weight: natural crushed stone 500-800 parts, river sand 400-550 parts, cement 300-360 parts, fly ash 80-100 parts, foaming agent 3-6 parts, SiO2 / aramid composite mesh cloth 15-30 parts and water 180-200 parts.

[0007] The SiO2 / aramid composite mesh cloth is SiO2 nanofiber film loaded on both sides of aramid fiber cloth, and the SiO2 / aramid composite mesh cloth has an area of 1cm 2 -10cm 2 .

[0008] The preparation method of the SiO2 / aramid composite modified high-strength foam concrete, the preparation method comprises the following steps:

[0009] S1. Mix the foaming agent and water in a ratio of 1:15-20, stir into foam, add SiO2 / aramid composite mesh cloth, stir together, and keep foaming;

[0010] S2. Mix natural crushed stone, river sand, cement and fly ash, dry mix evenly, then add the remaining water, stir evenly, and obtain a slurry;

[0011] S3. Add the foaming agent solution prepared in step S1 to the slurry prepared in step S2, mix and stir to prepare a uniform fluid slurry, and pour to obtain SiO2 / aramid composite modified high-strength foam concrete.

[0012] Preferably, the stirring time of the SiO2 / aramid composite mesh cloth in step S1 is 2-4 min.

[0013] Preferably, the mixing and stirring time in step S3 is 2-4 min.

[0014] Preferably, the SiO2 / aramid composite mesh cloth is prepared by the following steps:

[0015] S11. Preparation of mesh aramid fiber cloth: select double-stranded 21 tex twisted aramid filaments, weave the aramid filaments into plain weave with a warp density of 120-150 filaments per 10 cm and a weft density of 100-120 filaments per cm to form an aramid fiber cloth with a mesh structure;

[0016] S12. Preparation of SiO2 nanofiber membrane: prepare a PVA aqueous solution with a concentration of 25wt%, add tetraethyl orthosilicate to water, stir evenly, then add hydrochloric acid to adjust the pH of the solution to 3-4, continue to stir and hydrolyze, obtain a tetraethyl orthosilicate hydrolysate, then mix the PVA aqueous solution and the tetraethyl orthosilicate hydrolysate according to the ratio, then perform electrospinning, dry the electrospun membrane, and sinter to obtain a SiO2 nanofiber membrane;

[0017] S13. Finishing of aramid fiber cloth: add tetraethyl orthosilicate to water, stir evenly, then add hydrochloric acid to adjust the pH of the solution to 3-4, continue to stir and hydrolyze, obtain a tetraethyl orthosilicate hydrolysate, add fly ash to the hydrolysate, mix and stir evenly, then immerse the aramid fiber cloth in the mixed hydrolysate to fully coat the surface of the aramid fiber cloth with the hydrolysate;

[0018] S14. Preparation of SiO2 / aramid composite reticular cloth: the aramid fiber cloth obtained by finishing in step S13 is attached and adsorbed with the SiO2 nanofiber membrane prepared in step S12 on both sides, and dried to obtain the SiO2 / aramid composite reticular cloth.

[0019] Preferably, the molar ratio of tetraethyl orthosilicate and water in step S12 is 1:6.5-8.2, the hydrolysis time is 8-15h, and the volume ratio of PVA aqueous solution and the hydrolysis solution of tetraethyl orthosilicate is 1:1.5-2.5.

[0020] Preferably, the molar ratio of tetraethyl orthosilicate and water in step S13 is 1:8-10, and the content of fly ash in the tetraethyl orthosilicate hydrolysis solution is 10-15wt%.

[0021] Preferably, the drying temperature in step S14 is 90-120℃, and the time is 4-6h.

[0022] Beneficial effects: the SiO2 / aramid composite modified high-strength foam concrete has the following advantages:

[0023] In the present application, the SiO2 / aramid composite reticular cloth is used to reinforce the concrete. First, aramid filament is used to weave aramid fiber cloth. In order to make the aramid fiber cloth well blend with other components of the concrete, the warp density and weft density of the aramid fiber cloth are controlled to be relatively small when the aramid fiber cloth is manufactured. In this way, the woven aramid fiber cloth has a large porosity, which is convenient for the filling of the concrete. Second, the aramid fiber cloth is compounded on both sides to increase the rigidity of the aramid fiber cloth and improve the strength of the foam concrete.

[0024] In the present application, the SiO2 / aramid composite reticular cloth is directly cut to 1-10cm 2 Then it is directly added to the foaming solution. Since it is light in quality, it will not cause the collapse of the foam. After mixing with other components in the concrete, it can play a supporting role for the foam concrete. Both the aramid cloth and the SiO2 nanofiber membrane have pores. Part of the small particles of the concrete can enter the pores to improve the strength of the concrete.

[0025] In the present application, in addition to adding fly ash directly in the concrete, fly ash is also added in the compounding process of the SiO2 / aramid composite reticular cloth. The rigidity of the SiO2 / aramid composite reticular cloth is increased, and the strength of the concrete is improved. DETAILED DESCRIPTION

[0026] The present application will be further described below in conjunction with examples. The following examples are an explanation of the present application, and the present application is not limited to the following examples:

[0027] Example 1

[0028] A SiO2 / aramid composite modified high-strength foamed concrete, wherein the high-strength foamed concrete comprises the following components in parts by weight: 500 parts of natural crushed stone, 550 parts of river sand, 300 parts of cement, 80 parts of fly ash, 3 parts of foaming agent, 15 parts of SiO2 / aramid composite mesh cloth and 180 parts of water.

[0029] The SiO2 / aramid composite mesh fabric consists of aramid fiber fabric with SiO2 nanofiber membranes loaded on both sides. The SiO2 / aramid composite mesh fabric is selected with an area range of 1 cm². 2 -10cm 2 ;

[0030] The above-mentioned method for preparing SiO2 / aramid composite modified high-strength foamed concrete includes the following steps:

[0031] S1. Mix the foaming agent and water in a ratio of 1:15, stir to form foam, add SiO2 / aramid composite mesh cloth, stir together, stir for 4 minutes, and keep it in foam form;

[0032] S2. Mix natural crushed stone, river sand, cement and fly ash, dry mix evenly, add the remaining water, stir evenly to obtain slurry;

[0033] S3. Add the foaming agent solution prepared in step S1 to the slurry prepared in step S2, mix and stir for 4 minutes to form a uniform fluid slurry, and pour it to obtain SiO2 / aramid composite modified high-strength foamed concrete.

[0034] Preferably, the SiO2 / aramid composite mesh fabric is prepared by the following steps:

[0035] S11. Preparation of mesh aramid fiber cloth: Select double-strand 21tex twisted aramid filaments, and weave the aramid filaments into a plain weave with a warp density of 125 threads / 10cm and a weft density of 100 threads / cm to form an aramid fiber cloth with a mesh structure.

[0036] S12. Preparation of SiO2 nanofiber membrane: Prepare a 25wt% PVA aqueous solution, add tetraethyl orthosilicate to the water, the molar ratio of tetraethyl orthosilicate to water is 1:6.5, stir evenly, add hydrochloric acid to adjust the pH of the solution to 3, and continue stirring for 15h to hydrolyze to obtain tetraethyl orthosilicate hydrolysate. Mix the PVA aqueous solution and the tetraethyl orthosilicate hydrolysate at a volume ratio of 1:1.5, and then perform electrospinning. After drying the electrospun membrane, sinter it to obtain SiO2 nanofiber membrane;

[0037] S13. Finishing of aramid fiber cloth: tetraethyl orthosilicate is added to water, the molar ratio of tetraethyl orthosilicate to water is 1:10, hydrochloric acid is added after stirring uniformly, the pH of the solution is adjusted to 3, hydrolysis is continued under stirring, a tetraethyl orthosilicate hydrolysate is obtained, fly ash is added to the hydrolysate, the content of fly ash in the tetraethyl orthosilicate hydrolysate is 10wt%, after mixing and stirring uniformly, the aramid fiber cloth is immersed in the mixed hydrolysate so that the surface of the aramid fiber cloth is fully coated with the hydrolysate;

[0038] S14. Preparation of SiO2 / aramid composite mesh cloth: the aramid fiber cloth finished in step S13 is attached and adsorbed with the SiO2 nanofiber membrane prepared in step S12 on both sides, then dried, the drying temperature is 120℃, the drying time is 4h, and the SiO2 / aramid composite mesh cloth is obtained.

[0039] Example 2

[0040] A SiO2 / aramid composite modified high-strength foam concrete, the high-strength foam concrete comprises the following components by weight: natural crushed stone 800 parts, river sand 400 parts, cement 360 parts, fly ash 100 parts, foaming agent 6 parts, SiO2 / aramid composite mesh cloth 20 parts and water 200 parts;

[0041] The SiO2 / aramid composite mesh cloth is a SiO2 nanofiber membrane loaded on both sides of aramid fiber cloth, and the SiO2 / aramid composite mesh cloth is selected to have an area interval of 1cm 2 -10cm 2 ;

[0042] The preparation method of the above-mentioned SiO2 / aramid composite modified high-strength foam concrete, the preparation method comprises the following steps:

[0043] S1. Mix the foaming agent and water in a ratio of 1:20, stir into foam, add the SiO2 / aramid composite mesh cloth, stir together, and maintain the foam state for 2min;

[0044] S2. Mix the natural crushed stone, river sand, cement and fly ash, dry mix uniformly, then add the remaining water, and stir uniformly to obtain a slurry;

[0045] S3. Add the foaming agent solution prepared in step S1 to the slurry prepared in step S2, mix and stir for 2min to prepare a uniform fluid slurry, and then pour to obtain the SiO2 / aramid composite modified high-strength foam concrete.

[0046] Preferably, the SiO2 / aramid composite mesh cloth is prepared by the following steps:

[0047] S11. Preparation of the reticular aramid fiber cloth: select double-stranded 21 tex twisted aramid filaments, weave the aramid filaments into a plain weave with a warp density of 150 ends / 10 cm and a weft density of 120 ends / cm to form an aramid fiber cloth with a reticular structure;

[0048] S12. Preparation of the SiO2 nanofiber membrane: prepare a PVA aqueous solution with a concentration of 25 wt%, add tetraethyl orthosilicate to the water, the molar ratio of tetraethyl orthosilicate to water is 1:8.2, after stirring uniformly, add hydrochloric acid to adjust the pH of the solution to 4, continue to stir for 8 h to obtain a tetraethyl orthosilicate hydrolysate, then mix the PVA aqueous solution and the tetraethyl orthosilicate hydrolysate according to a volume ratio of 1:2.5, and then perform electrospinning, dry the electrospun membrane and sinter to obtain a SiO2 nanofiber membrane;

[0049] S13. Finishing of the aramid fiber cloth: add tetraethyl orthosilicate to water, the molar ratio of tetraethyl orthosilicate to water is 1:8, after stirring uniformly, add hydrochloric acid to adjust the pH of the solution to 3, continue to stir for hydrolysis, obtain a tetraethyl orthosilicate hydrolysate, add fly ash to the hydrolysate, the content of fly ash in the tetraethyl orthosilicate hydrolysate is 15 wt%, after stirring uniformly, immerse the aramid fiber cloth in the mixed hydrolysate to fully coat the surface of the aramid fiber cloth with the hydrolysate;

[0050] S14. Preparation of the SiO2 / aramid composite reticular cloth: attach and adsorb the SiO2 nanofiber membrane prepared in step S12 on both sides of the aramid fiber cloth finished in step S13, then dry, the drying temperature is 90°C, and the drying time is 6 h, to obtain a SiO2 / aramid composite reticular cloth.

[0051] Example 3

[0052] A SiO2 / aramid composite modified high-strength foam concrete, the high-strength foam concrete comprises the following components by weight: natural crushed stone 600 parts, river sand 500 parts, cement 320 parts, fly ash 85 parts, foaming agent 4 parts, SiO2 / aramid composite reticular cloth 18 parts, and water 180 parts;

[0053] The SiO2 / aramid composite reticular cloth is a SiO2 nanofiber membrane loaded on both sides of the aramid fiber cloth, and the SiO2 / aramid composite reticular cloth has an area of 3 cm 2 -7 cm 2 ;

[0054] The preparation method of the above-mentioned SiO2 / aramid composite modified high-strength foam concrete, the preparation method comprises the following steps:

[0055] S1. Mix the foaming agent and water in a ratio of 1:15, stir to form foam, add SiO2 / aramid composite mesh cloth, stir together, stir for 4 minutes, and keep it in foam form;

[0056] S2. Mix natural crushed stone, river sand, cement and fly ash, dry mix evenly, add the remaining water, stir evenly to obtain slurry;

[0057] S3. Add the foaming agent solution prepared in step S1 to the slurry prepared in step S2, mix and stir for 2 minutes to form a uniform fluid slurry, and pour it to obtain SiO2 / aramid composite modified high-strength foamed concrete.

[0058] Preferably, the SiO2 / aramid composite mesh fabric is prepared by the following steps:

[0059] S11. Preparation of mesh aramid fiber cloth: Select double-strand 21tex twisted aramid filaments, and weave the aramid filaments into a plain weave with a warp density of 125 threads / 10cm and a weft density of 105 threads / cm to form an aramid fiber cloth with a mesh structure.

[0060] S12. Preparation of SiO2 nanofiber membrane: Prepare a 25wt% PVA aqueous solution, add tetraethyl orthosilicate to the water, the molar ratio of tetraethyl orthosilicate to water is 1:6.8, stir evenly, add hydrochloric acid to adjust the pH of the solution to 4, and continue stirring and hydrolyzing for 10h to obtain tetraethyl orthosilicate hydrolysate. Mix the PVA aqueous solution and the tetraethyl orthosilicate hydrolysate at a volume ratio of 1:2.2, and then perform electrospinning. After drying the electrospun membrane, sinter it to obtain SiO2 nanofiber membrane;

[0061] S13. Finishing of aramid fiber cloth: Tetraethyl orthosilicate is added to water at a molar ratio of 1:8. After stirring evenly, hydrochloric acid is added to adjust the pH of the solution to 3. The solution is continuously stirred and hydrolyzed to obtain a tetraethyl orthosilicate hydrolysate. Fly ash is added to the hydrolysate at a content of 14 wt%. After mixing and stirring evenly, the aramid fiber cloth is immersed in the mixed hydrolysate to fully coat its surface with the hydrolysate.

[0062] S14. Preparation of SiO2 / aramid composite mesh: The SiO2 nanofiber membrane prepared in step S12 is adsorbed onto both sides of the aramid fiber cloth obtained in step S13, and then dried at 100℃ for 6 hours to obtain SiO2 / aramid composite mesh.

[0063] Example 4

[0064] SiO2 / aramid composite modified high-strength foam concrete, the high-strength foam concrete comprises the following components in parts by weight: natural crushed stone 700 parts, river sand 450 parts, cement 340 parts, fly ash 95 parts, foaming agent 5 parts, SiO2 / aramid composite mesh cloth 25 parts and water 200 parts;

[0065] The SiO2 / aramid composite mesh cloth is a SiO2 nanofiber film loaded on both sides of an aramid fiber cloth, and the SiO2 / aramid composite mesh cloth has an area of 3 cm 2 -7 cm 2 ;

[0066] The preparation method of the SiO2 / aramid composite modified high-strength foam concrete comprises the following steps:

[0067] S1. Mix the foaming agent and water in a ratio of 1:20, stir into foam, add the SiO2 / aramid composite mesh cloth, and stir together for 2 min to maintain the foam state;

[0068] S2. Mix the natural crushed stone, river sand, cement and fly ash, dry mix uniformly, then add the remaining water and stir uniformly to obtain a slurry;

[0069] S3. Add the foaming agent solution prepared in step S1 to the slurry prepared in step S2, mix and stir for 4 min to prepare a uniform fluid slurry, and then cast to obtain the SiO2 / aramid composite modified high-strength foam concrete.

[0070] Preferably, the SiO2 / aramid composite mesh cloth is prepared by the following steps:

[0071] S11. Preparation of mesh aramid fiber cloth: select double-stranded 21 tex twisted aramid filaments, weave the aramid filaments into a plain weave with a warp density of 140 filaments / 10 cm and a weft density of 115 filaments / cm to form an aramid fiber cloth with a mesh structure;

[0072] S12. Preparation of SiO2 nanofiber membrane: prepare a PVA aqueous solution with a concentration of 25 wt%, add tetraethyl orthosilicate to water, the molar ratio of tetraethyl orthosilicate to water is 1:7.8, after stirring uniformly, add hydrochloric acid to adjust the pH of the solution to 3, continue to stir for 14 h to obtain a tetraethyl orthosilicate hydrolysate, then mix the PVA aqueous solution and the tetraethyl orthosilicate hydrolysate according to a volume ratio of 1:1.8, then perform electrospinning, dry the electrospun membrane and sinter to obtain a SiO2 nanofiber membrane;

[0073] S13. Finishing of aramid fiber cloth: tetraethyl orthosilicate is added to water, the molar ratio of tetraethyl orthosilicate to water is 1:10, hydrochloric acid is added after stirring uniformly, the pH of the solution is adjusted to 4, hydrolysis is continued under stirring, a tetraethyl orthosilicate hydrolysate is obtained, fly ash is added to the hydrolysate, the content of fly ash in the tetraethyl orthosilicate hydrolysate is 12wt%, after mixing and stirring uniformly, the aramid fiber cloth is immersed in the mixed hydrolysate so that the surface of the aramid fiber cloth is fully coated with the hydrolysate;

[0074] S14. Preparation of SiO2 / aramid composite mesh cloth: the aramid fiber cloth finished in step S13 is attached and adsorbed with the SiO2 nanofiber membrane prepared in step S12 on both sides, then dried, the drying temperature is 115℃, the time is 6h, and the SiO2 / aramid composite mesh cloth is obtained.

[0075] Example 5

[0076] A SiO2 / aramid composite modified high-strength foam concrete, the high-strength foam concrete comprises the following components by weight: natural crushed stone 650 parts, river sand 460 parts, cement 330 parts, fly ash 90 parts, foaming agent 4.5 parts, SiO2 / aramid composite mesh cloth 30 parts and water 190 parts;

[0077] The SiO2 / aramid composite mesh cloth is a SiO2 nanofiber membrane loaded on both sides of aramid fiber cloth, and the SiO2 / aramid composite mesh cloth has an area of 4cm 2 -6cm 2 ;

[0078] The preparation method of the above-mentioned SiO2 / aramid composite modified high-strength foam concrete comprises the following steps:

[0079] S1. Mix the foaming agent and water in a ratio of 1:18, stir into foam, add the SiO2 / aramid composite mesh cloth, stir together, and maintain the foam state for 3min;

[0080] S2. Mix the natural crushed stone, river sand, cement and fly ash, dry mix uniformly, then add the remaining water and stir uniformly to obtain a slurry;

[0081] S3. Add the foaming agent solution prepared in step S1 to the slurry prepared in step S2, mix and stir for 3min to prepare a uniform fluid slurry, and then pour to obtain the SiO2 / aramid composite modified high-strength foam concrete.

[0082] Preferably, the SiO2 / aramid composite mesh cloth is prepared by the following steps:

[0083] S11. Preparation of the reticular aramid fiber cloth: double-stranded 21 tex twisted aramid filaments are selected, the aramid filaments are woven into the aramid fiber cloth with a reticular structure by using plain weave, the warp density is 130 roots / 10 cm, and the weft density is 110 roots / cm;

[0084] S12. Preparation of the SiO2 nanofiber membrane: a PVA aqueous solution with a concentration of 25wt% is configured, tetraethyl orthosilicate is added to the water, the molar ratio of the tetraethyl orthosilicate to the water is 1:7.2, hydrochloric acid is added after uniform stirring, the pH of the solution is adjusted to 3, and the hydrolysis is continued for 12 hours, thereby obtaining a tetraethyl orthosilicate hydrolysate, the PVA aqueous solution and the tetraethyl orthosilicate hydrolysate are mixed in a volume ratio of 1:2, and then electrospinning is performed, the electrospun membrane is dried and sintered to obtain the SiO2 nanofiber membrane;

[0085] S13. Finishing of the aramid fiber cloth: tetraethyl orthosilicate is added to the water, the molar ratio of the tetraethyl orthosilicate to the water is 1:9, hydrochloric acid is added after uniform stirring, the pH of the solution is adjusted to 3, and the hydrolysis is continued, thereby obtaining a tetraethyl orthosilicate hydrolysate, fly ash is added to the hydrolysate, the content of the fly ash in the tetraethyl orthosilicate hydrolysate is 13wt%, and the aramid fiber cloth is immersed in the mixed hydrolysate so that the surface of the aramid fiber cloth is fully coated with the hydrolysate;

[0086] S14. Preparation of the SiO2 / aramid composite reticular cloth: the aramid fiber cloth finished in step S13 is attached and adsorbed with the SiO2 nanofiber membrane prepared in step S12 on both sides, and then dried, the drying temperature is 110°C, and the drying time is 5h, thereby obtaining the SiO2 / aramid composite reticular cloth.

[0087] Comparative Example 1

[0088] An aramid modified high-strength foam concrete, the high-strength foam concrete comprises the following components by weight: natural crushed stone 650 parts, river sand 460 parts, cement 330 parts, fly ash 90 parts, foaming agent 4.5 parts, aramid fiber cloth 15 parts, and water 200 parts;

[0089] The aramid fiber cloth has an area of 4cm 2 -6cm 2 ;

[0090] The preparation method of the aramid modified high-strength foam concrete, the preparation method comprises the following steps:

[0091] S1. Selecting double-stranded 21 tex twisted aramid filaments, weaving the aramid filaments into aramid fiber cloth with a reticular structure by using plain weave, the warp density is 130 roots / 10 cm, and the weft density is 110 roots / cm;

[0092] S2. Add tetraethyl orthosilicate into water, the molar ratio of tetraethyl orthosilicate and water is 1:9, after stirring evenly, add hydrochloric acid, adjust the pH of the solution to 3, continue to stir hydrolysis, obtain tetraethyl orthosilicate hydrolyzate, add fly ash into the tetraethyl orthosilicate hydrolyzate, the content of fly ash in the tetraethyl orthosilicate hydrolyzate is 13wt%, after mixing and stirring evenly, dip aramid fiber cloth into the mixed hydrolyzate, make its surface fully coated with the hydrolyzate, then dry, the drying temperature is 110℃, the time is 5h, obtain aramid fiber cloth;

[0093] S3. Mix the foaming agent and water according to the ratio of 1:18, stir into foam, add aramid fiber cloth, stir together, the stirring time is 3min, keep foaming;

[0094] S4. Mix natural crushed stone, river sand, cement and fly ash, dry mix evenly, then add the remaining water, stir evenly, obtain slurry;

[0095] S5. Add the foaming agent solution prepared in step S3 into the slurry prepared in step S4, mix and stir for 3min, make uniform fluid slurry, cast to obtain aramid modified high-strength foam concrete.

[0096] Comparative example 2

[0097] A SiO2 / aramid composite modified high-strength foam concrete, the high-strength foam concrete comprises the following components by weight: natural crushed stone 700 parts, river sand 450 parts, cement 340 parts, fly ash 95 parts, foaming agent 5 parts, SiO2 / aramid composite mesh cloth 18 parts and water 200 parts;

[0098] The SiO2 / aramid composite mesh cloth is SiO2 nanofiber film loaded on both sides of aramid fiber cloth, the SiO2 / aramid composite mesh cloth selected has an area of 3cm 2 -7cm 2 ;

[0099] The preparation method of the above-mentioned SiO2 / aramid composite modified high-strength foam concrete, the preparation method comprises the following steps:

[0100] S1. Mix the foaming agent and water according to the ratio of 1:20, stir into foam, add SiO2 / aramid composite mesh cloth, stir together, the stirring time is 2min, keep foaming;

[0101] S2. Mix natural crushed stone, river sand, cement and fly ash, dry mix evenly, then add the remaining water, stir evenly, obtain slurry;

[0102] S3. The foaming agent solution prepared in step S1 is added to the slurry prepared in step S2, mixed and stirred for 4 min to prepare a uniform and fluid slurry, and then cast to obtain SiO2 / aramid composite modified high-strength foam concrete;

[0103] Preferably, the SiO2 / aramid composite mesh cloth is prepared by the following steps:

[0104] S11. Preparation of mesh aramid fiber cloth: double-stranded 21 tex twisted aramid filaments are selected, and the aramid filaments are woven into a mesh structure aramid fiber cloth with a weft density of 140 roots / 10 cm and a weft density of 115 roots / cm;

[0105] S12. Preparation of SiO2 nanofiber membrane: a PVA aqueous solution with a concentration of 25wt% is prepared, tetraethyl orthosilicate is added to water, the molar ratio of tetraethyl orthosilicate to water is 1:7.8, hydrochloric acid is added after stirring, the pH of the solution is adjusted to 3, and the hydrolysis is continued for 14h to obtain a tetraethyl orthosilicate hydrolysate, then the PVA aqueous solution and the tetraethyl orthosilicate hydrolysate are mixed in a volume ratio of 1:1.8, and then electrospinning is performed, and the electrospinning membrane is dried and sintered to obtain a SiO2 nanofiber membrane;

[0106] S13. Finishing of aramid fiber cloth: tetraethyl orthosilicate is added to water, the molar ratio of tetraethyl orthosilicate to water is 1:10, hydrochloric acid is added after stirring, the pH of the solution is adjusted to 4, and the hydrolysis is continued to obtain a tetraethyl orthosilicate hydrolysate, and the aramid fiber cloth is immersed in the mixed hydrolysate to fully coat the surface of the aramid fiber cloth with the hydrolysate;

[0107] S14. Preparation of SiO2 / aramid composite mesh cloth: the aramid fiber cloth finished in step S13 has SiO2 nanofiber membranes attached and adsorbed on both sides, and then dried at a temperature of 115°C for 6h to obtain a SiO2 / aramid composite mesh cloth.

[0108] Comparative Example 3

[0109] A SiO2 / aramid composite modified high-strength foam concrete, the high-strength foam concrete comprising the following components by weight: natural crushed stone 600 parts, river sand 500 parts, cement 320 parts, fly ash 85 parts, foaming agent 4 parts, SiO2 / aramid composite mesh cloth 8 parts, and water 180 parts;

[0110] The SiO2 / aramid composite mesh cloth is a SiO2 nanofiber membrane loaded on both sides of the aramid fiber cloth, and the SiO2 / aramid composite mesh cloth has an area of 13cm 2 -18cm 2 ;

[0111] The preparation method of the SiO2 / aramid composite modified high-strength foam concrete, the preparation method comprises the following steps:

[0112] S1. Mix the foaming agent and water in a ratio of 1:15, stir into foam, add SiO2 / aramid composite mesh cloth, stir together, stirring time is 4 min, keep foaming;

[0113] S2. Mix natural crushed stone, river sand, cement and fly ash, dry mix evenly, then add the remaining water, stir evenly to get slurry;

[0114] S3. Add the foaming agent solution prepared in step S1 to the slurry prepared in step S2, mix and stir for 2 min to make a uniform fluid slurry, and pour to get SiO2 / aramid composite modified high-strength foam concrete.

[0115] Preferably, the SiO2 / aramid composite mesh cloth is prepared by the following steps:

[0116] S11. Preparation of mesh aramid fiber cloth: select double-stranded 21 tex twisted aramid filaments, weave the aramid filaments into a plain weave with a warp density of 125 roots / 10 cm and a weft density of 105 roots / cm to form an aramid fiber cloth with a mesh structure;

[0117] S12. Preparation of SiO2 nanofiber membrane: prepare a PVA aqueous solution with a concentration of 25wt%, add tetraethyl orthosilicate to water, the molar ratio of tetraethyl orthosilicate to water is 1:6.8, after stirring evenly, add hydrochloric acid to adjust the pH of the solution to 4, continue to stir for 10h to obtain a tetraethyl orthosilicate hydrolysate, then mix the PVA aqueous solution and the tetraethyl orthosilicate hydrolysate according to a volume ratio of 1:2, then perform electrospinning, dry the electrospun membrane and sinter to obtain a SiO2 nanofiber membrane;

[0118] S13. Finishing of aramid fiber cloth: add tetraethyl orthosilicate to water, the molar ratio of tetraethyl orthosilicate to water is 1:8, after stirring evenly, add hydrochloric acid to adjust the pH of the solution to 3, continue to stir for hydrolysis, obtain a tetraethyl orthosilicate hydrolysate, add fly ash to the hydrolysate, the content of fly ash in the tetraethyl orthosilicate hydrolysate is 12wt%, after mixing and stirring evenly, immerse the aramid fiber cloth in the mixed hydrolysate to fully coat the surface of the aramid fiber cloth with the hydrolysate;

[0119] S14. Preparation of SiO2 / aramid composite mesh cloth: attach and adsorb the SiO2 nanofiber membrane prepared in step S12 on both sides of the aramid fiber cloth finished in step S13, then dry, the drying temperature is 100℃, the time is 6h, to obtain SiO2 / aramid composite mesh cloth.

[0120] Performance test:

[0121] The compressive strength test selected size of 100 mm*100 mm*100 mm cube specimens, compressive strength test in 2000kN press, wherein the compressive strength test loading rate of 0.3-0.5MPa / s.

[0122] Table 1 is the compressive strength of different curing age

[0123] 20d 40d 60d 80d Example 1 39.8 47.6 51.6 55..9 Example 2 36.8 45.9 50.1 54.2 Example 3 39.5 47.5 51.3 55.8 Example 4 40.1 48.9 52.6 56.8 Example 5 40.8 48.8 52.9 57.1 Comparative Example 1 28.6 32.9 36.1 37.7 Comparative Example 2 35.1 38.6 40.9 42.3 Comparative Example 3 20.5 25.6 27.8 30.5

[0124] Obviously, the above examples are merely illustrative examples for clarity, and not limited to the embodiments. For those of ordinary skill in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A SiO2 / aramid composite modified high-strength foamed concrete, characterized in that, The high-strength foamed concrete comprises the following components by weight: 500-800 parts of natural crushed stone, 400-550 parts of river sand, 300-360 parts of cement, 80-100 parts of fly ash, 3-6 parts of foaming agent, 15-30 parts of SiO2 / aramid composite mesh cloth, and 180-200 parts of water. The SiO2 / aramid composite mesh fabric consists of aramid fiber fabric with SiO2 nanofiber membranes loaded on both sides. The SiO2 / aramid composite mesh fabric has an area of ​​1 cm². 2 -10cm 2 .

2. The method for preparing SiO2 / aramid composite modified high-strength foamed concrete according to claim 1, characterized in that, The preparation method includes the following steps: S1. Mix the foaming agent and water in a ratio of 1:15-20, stir to form foam, add SiO2 / aramid composite mesh cloth, stir together, and maintain the foam state; S2. Mix natural crushed stone, river sand, cement and fly ash, dry mix evenly, add the remaining water, stir evenly to obtain slurry; S3. Add the foaming agent solution prepared in step S1 to the slurry prepared in step S2, mix and stir to form a uniform fluid slurry, and pour it to obtain SiO2 / aramid composite modified high-strength foamed concrete.

3. The method for preparing SiO2 / aramid composite modified high-strength foamed concrete according to claim 1, characterized in that: In step S1, the stirring time for adding the SiO2 / aramid composite mesh is 2-4 minutes.

4. The method for preparing SiO2 / aramid composite modified high-strength foamed concrete according to claim 1, characterized in that: The mixing and stirring time in step S3 is 2-4 minutes.

5. The method for preparing SiO2 / aramid composite modified high-strength foamed concrete according to claim 1, characterized in that, The SiO2 / aramid composite mesh fabric is prepared by the following steps: S11. Preparation of mesh aramid fiber cloth: Select double-strand 21tex twisted aramid filaments, and weave the aramid filaments into a plain weave with a warp density of 120-150 threads / 10cm and a weft density of 100-120 threads / cm to form an aramid fiber cloth with a mesh structure. S12. Preparation of SiO2 nanofiber membrane: Prepare a 25wt% PVA aqueous solution, add tetraethyl orthosilicate to the water, stir evenly, add hydrochloric acid, adjust the pH of the solution to 3-4, and continue stirring to hydrolyze to obtain tetraethyl orthosilicate hydrolysate. Mix the PVA aqueous solution and tetraethyl orthosilicate hydrolysate in a certain proportion, and then perform electrospinning. After drying the electrospun membrane, sinter it to obtain SiO2 nanofiber membrane. S13. Finishing of aramid fiber cloth: Add tetraethyl orthosilicate to water, stir evenly, add hydrochloric acid, adjust the pH of the solution to 3-4, continue stirring to hydrolyze, and obtain tetraethyl orthosilicate hydrolysate. Add fly ash to the hydrolysate, mix and stir evenly, and then immerse the aramid fiber cloth in the mixed hydrolysate to fully coat its surface with the hydrolysate. S14. Preparation of SiO2 / aramid composite mesh: The SiO2 nanofiber membrane prepared in step S12 is adsorbed onto both sides of the aramid fiber cloth obtained in step S13, and then dried to obtain SiO2 / aramid composite mesh.

6. The method for preparing SiO2 / aramid composite modified high-strength foamed concrete according to claim 1, characterized in that: In step S12, the molar ratio of tetraethyl orthosilicate to water is 1:6.5-8.2, the hydrolysis time is 8-15 h, and the volume ratio of PVA aqueous solution to tetraethyl orthosilicate hydrolysate is 1:1.5-2.

5.

7. The method for preparing SiO2 / aramid composite modified high-strength foamed concrete according to claim 1, characterized in that: In step S13, the molar ratio of tetraethyl orthosilicate to water is 1:8-10, and the content of fly ash in the tetraethyl orthosilicate hydrolysate is 10-15 wt%.

8. The method for preparing SiO2 / aramid composite modified high-strength foamed concrete according to claim 1, characterized in that: In step S14, the drying temperature is 90-120℃ and the time is 4-6 hours.