Method for producing a maintenance-free concrete

Abstract

The application relates to the technical field of building materials, and discloses a preparation method of maintenance-free concrete, and the specific steps are as follows: S1. binding steel bars, wherein the steel bars are provided with porous steel pipes, and the porous steel pipes are filled with water-saturated sand washing or water-absorbing resin; S2. erecting a concrete heat insulation template; S3. spraying silica sol or saturated calcium hydroxide solution on the surface of concrete aggregates, and pouring concrete, wherein the concrete contains fiber tubes, cellulose and cellulose fibers; and S4. after the concrete is poured and initial setting, before final setting, spraying a concrete protective layer material on the surface of the concrete, and then carrying out second-time troweling and light receiving. The application solves the problem that the performance of the concrete is greatly reduced when the maintenance condition is not met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a preparation method of maintenance-free concrete. BACKGROUND

[0002] Concrete is a kind of artificial stone made of cementitious materials, sand and stone aggregates, water and other additives according to suitable proportions. The development of the strength of cast-in-place concrete requires certain humidity and temperature conditions. When the construction site does not have maintenance conditions, the water on the surface of the concrete is easy to evaporate, which can cause cracking or strength reduction of the concrete, and the strength does not meet the standard.

[0003] At present, the domestic concrete construction generally adopts the traditional methods of natural maintenance by watering, maintenance by covering film, and maintenance by covering geotextile. In winter, building electric blankets are also used for maintenance. The above methods are not easy to implement under special environmental conditions. The watering frequency and time need to be adjusted according to the temperature at the time of construction and the size of the concrete member. The film used for maintenance by covering film is not easy to fix and is easy to damage, resulting in poor maintenance effect. The geotextile is flammable and difficult to recycle. The maintenance-free concrete can well solve the above problems, which not only reduces the labor cost but also saves water resources. In areas where water resources are scarce and water is inconvenient to use, the construction can also be guaranteed.

[0004] At present, there are various ways to maintain concrete, one of which is to spray an inhibitor on the surface of the concrete to achieve maintenance. The inhibitor will form a film on the surface of the concrete to inhibit the evaporation of water in the concrete, thereby achieving the purpose of maintenance.

[0005] Patent 200810014216.8 discloses a concrete curing agent, which comprises a benzyl acrylate emulsion, an acrylamide solution, a sodium silicate solution and an organic silane solution. By blocking the capillary pore channel, a strong waterproof layer is formed, which prevents the internal water from evaporating and prevents external harmful substances from entering, thereby helping to improve the durability of the concrete.

[0006] Patent 201710512187.7 discloses an environmentally friendly concrete curing agent and a preparation method thereof, which comprises: 20-25 parts of high-grade fatty acid, 15-20 parts of industrial paraffin, 3-8 parts of stearic acid, 2-3 parts of rosin, 0.5-1.5 parts of caustic soda, 0.2-0.8 parts of triethanolamine, and 180-220 parts of water. The film formed by the invention has good water retention and is easy to peel off.

[0007] Patent 201910124783.7 grafts acrylic monomers onto carboxymethyl cellulose as a base to prepare a composite emulsion as a raw material for a composite concrete curing agent, and then adds water glass, urea and sodium methylsilanol to prepare a composite concrete curing agent with good water retention.

[0008] Patent 202011494072.8 discloses a concrete curing agent, which comprises the following raw materials in parts by weight: paraffin emulsion 10-15 parts, styrene-acrylic emulsion 10-20 parts, repair microcapsule 5-10 parts, sodium silicate 5-8 parts, magnesium sulfate 5-8 parts, aluminum sulfate 5-8 parts, animal and plant fibers 4-10 parts, methyl methacrylate 10-20 parts, defoaming agent 1-1.5 parts, leveling agent 1-3 parts, plasticizer 0.2-0.4 parts and deionized water 20-30 parts.

[0009] Patent 202110096319.9 discloses a concrete curing agent, which comprises, in mass parts, 10-80 parts of sodium silicate, 5-60 parts of paraffin emulsion, 1-10 parts of urea, 1-10 parts of coupling agent, 1-10 parts of alkanolamine, 1-10 parts of sodium fluorosilicate, 1-20 parts of film-forming agent, 5-30 parts of superabsorbent resin, 1-20 parts of gelatin, 1-20 parts of diatomite and 90-150 parts of water.

[0010] Although the above curing agent reduces the evaporation of free water in the concrete to some extent, it also causes the reduction of the strength of the concrete. SUMMARY

[0011] The purpose of the application is to provide a preparation method of maintenance-free concrete, which solves the problem of significant reduction of concrete strength and other performances when curing conditions are not available.

[0012] Technical scheme: The application provides a preparation method of maintenance-free concrete, which comprises the following steps:

[0013] S1. Binding the steel bars, wherein the steel bars are provided with a perforated steel pipe filled with water-saturated sand or water-absorbing resin;

[0014] S2. Erecting a concrete heat-insulating formwork;

[0015] S3. Spraying silica sol or saturated calcium hydroxide solution on the surface of concrete aggregate, and pouring concrete; the concrete contains fiber tubes, cellulose and cellulose fibers;

[0016] S4. Spraying a concrete protective layer material on the surface of the concrete after pouring and before final setting, and then performing second-time troweling and polishing; the protective layer material comprises, in parts by weight, ordinary portland cement 50-100 parts, sulphoaluminate cement 20-50 parts, limestone powder 10-30 parts, quartz sand powder 10-30 parts, sodium carbonate 1-10 parts, sodium silicate 1-10 parts, aluminum sulfate 1-10 parts, and redispersible glue powder 1-10 parts.

[0017] Further, in S3, the fiber tube is a porous fiber tube; the cellulose fiber needs to be boiled at high temperature; before use, the fiber tube and the cellulose fiber need to be soaked in a composite ion solution with a mass fraction of 0.05-1% for treatment, and the composite ion solution is composed of 10-40% sodium silicate, 10-30% sodium carbonate, 5-30% sodium hydroxide, 5-30% potassium hydroxide, 1-10% urea, and 1-10% triethanolamine by weight.

[0018] Further, the content of the fiber tube in the concrete is 0.5-5 kg / m 3 ; the content of the cellulose in the concrete is 0.5-2 kg / m 3 ; and the content of the cellulose fiber in the concrete is 0.5-5 kg / m 3 .

[0019] Further, in S1, the volume of the porous steel tube is 10-40% of the volume of the steel bar.

[0020] Further, in S1, the particle size of the sand-saturated or water-absorbing resin is less than 2 mm.

[0021] Further, in S3, the silica sol is a silica sol with a concentration of 0.01-1%.

[0022] Further, in S3, the spraying amount of the silica sol or the saturated calcium hydroxide solution is 0.5-2 kg of silica sol or saturated calcium hydroxide solution per ton of concrete aggregate.

[0023] Further, in S4, the spraying amount of the protective layer material is 50-200 g of protective layer material per square meter of concrete surface.

[0024] Preferably, in S3, the concrete aggregate needs to be cleaned before use.

[0025] Beneficial effects: Compared with the prior art, the beneficial effects of the present application are:

[0026] 1) By using silica sol or saturated calcium hydroxide solution to infiltrate the surface of the concrete aggregate, and by the action of carbon dioxide in the air, nanocrystalline nuclei are deposited on the surface of the concrete aggregate, which can promote the hydration of cement; at the same time, by using the thermal insulation concrete formwork, the heat loss of the heat released during the hydration of concrete is reduced, and the heat of the hydration heat is utilized to accelerate the hydration of cement, thereby reducing the water loss caused by the long setting time of concrete.

[0027] 2) The concrete protective layer material is used for finishing and collecting light, can absorb the bleeding water on the surface of the concrete, fill and repair the bleeding water channel on the surface of the concrete, and harden on the surface of the concrete quickly to seal the water in the concrete, thereby reducing the loss of water in the concrete. In the protective layer material, sodium carbonate, sodium silicate, aluminum sulfate and the like can consume calcium hydroxide in the concrete to form calcium carbonate, calcium silicate, ettringite and the like to fill the holes on the surface of the concrete, and limestone powder and quartz sand powder mainly play the role of filler and aggregate to solve the surface layer sanding and peeling phenomenon caused by the sinking of the aggregate on the surface of the concrete.

[0028] 3) The use of water-saturated ceramic sand and water-absorbing resin in the porous steel pipe solves the problem of water supplement for the concrete and the problem of reduction of the strength of the concrete caused by the use of ceramic sand and water-absorbing resin under normal conditions.

[0029] 4) The use of cellulose fiber and fiber tube can improve the crack resistance of the concrete, and in the case of water shortage of the concrete, in addition to supplementing alkaline water for the concrete, the unreacted cement particles and auxiliary cementitious materials in the concrete can be excited to store power for the later strength of the concrete. Embodiment

[0030] The application will be described in detail in combination with the embodiments.

[0031] Embodiment 1

[0032] The embodiment provides a preparation method of maintenance-free concrete, and the specific steps are as follows:

[0033] Step 1) binding the steel bars, wherein the steel bars are provided with the porous steel pipe with a volume fraction of 20% of the ordinary steel bars, and the porous steel pipe is filled with water-saturated ceramic sand with a particle size less than 2 mm;

[0034] Step 2) erecting the concrete heat insulation template;

[0035] Step 3) pouring the concrete, wherein the aggregate in the concrete needs to be cleaned before use, and 1% silica sol is sprayed, and the spraying amount of each ton of aggregate is 0.5 kg; the concrete further contains 5 kg / m 3 of fiber tube, 0.5 kg / m 3 of cellulose, and 0.5 kg / m 3 of cellulose fiber; the fiber tube is a porous fiber tube, and the cellulose fiber needs to be boiled at high temperature; before use, the fiber tube and the cellulose fiber need to be immersed in a composite ion solution with a mass fraction of 0.05%, and the composite ion solution is composed of 40% sodium silicate, 20% sodium carbonate, 19% sodium hydroxide, 19% potassium hydroxide, 1% urea and 1% triethanolamine;

[0036] Step 4) After the concrete is poured, initial setting and before final setting, 200g of concrete protective layer material is sprayed on each square of the concrete surface, and then the second finishing is carried out; the concrete protective layer material comprises ordinary Portland cement 100 parts, sulphoaluminate cement 20 parts, limestone powder 30 parts, quartz sand powder 10 parts, sodium carbonate 1 part, sodium silicate 1 part, aluminum sulfate 5 parts, and redispersible glue powder 1 part.

[0037] Embodiment 2

[0038] The embodiment provides a preparation method of the maintenance-free concrete, and specific steps are as follows:

[0039] Step 1) binding steel bars, wherein the steel bars are provided with porous steel pipes with a volume fraction of 10% of ordinary steel bars, and the porous steel pipes are filled with water-saturated water-absorbing resins;

[0040] Step 2) erecting a concrete heat insulation template;

[0041] Step 3) pouring concrete, wherein the aggregate in the concrete needs to be cleaned before use, and saturated calcium hydroxide solution is sprayed on the aggregate, and the spraying amount of the solution is 2kg per ton of aggregate; the concrete further contains 0.5kg / m 3 of fiber tubes, 2kg / m 3 of cellulose and 5kg / m 3 of cellulose fibers; the fiber tubes are porous fiber tubes, and the cellulose fibers need to be boiled at high temperature; before use, the fiber tubes and the cellulose fibers need to be immersed in a composite ion solution with a mass fraction of 1%, and the composite ion solution is composed of 10% sodium silicate, 30% sodium carbonate, 30% sodium hydroxide, 10% potassium hydroxide, 10% urea and 10% triethanolamine;

[0042] Step 4) After the concrete is poured, initial setting and before final setting, 200g of concrete protective layer material is sprayed on each square of the concrete surface, and then the second finishing is carried out; the concrete protective layer material comprises ordinary Portland cement 100 parts, sulphoaluminate cement 20 parts, limestone powder 30 parts, quartz sand powder 10 parts, sodium carbonate 1 part, sodium silicate 1 part, aluminum sulfate 5 parts, and redispersible glue powder 1 part.

[0043] Embodiment 3

[0044] The embodiment provides a preparation method of the maintenance-free concrete, and specific steps are as follows:

[0045] Step 1) binding steel bars, wherein the steel bars are provided with porous steel pipes with a volume fraction of 40% of ordinary steel bars, and the porous steel pipes are filled with water-saturated sand with a particle size of less than 2mm;

[0046] Step 2) erecting a concrete heat insulation template;

[0047] Step 3) pouring concrete, the aggregate in the concrete needs clean surface before use, and spraying 0.05% concentration of silica sol, the spraying amount of each ton of aggregate is 1kg; the concrete also contains 2kg / m 3 of fiber tube, 1kg / m 3 of cellulose and 2kg / m 3 of cellulose fiber; the fiber tube is a porous fiber tube, the cellulose fiber needs to be boiled at high temperature; the fiber tube and the cellulose fiber need to be immersed into a composite ion solution with a mass fraction of 0.1% before use, the composite ion solution is composed of 20% sodium silicate, 20% sodium carbonate, 25% sodium hydroxide, 20% potassium hydroxide, 7% urea and 8% triethanolamine;

[0048] Step 4) after the concrete is poured and after initial setting and before final setting, 100g of concrete protective layer material is sprayed on each square of concrete surface, and then the second finishing and polishing are carried out; the concrete protective layer material includes ordinary portland cement 70 parts, sulphoaluminate cement 30 parts, limestone powder 30 parts, quartz sand powder 30 parts, sodium carbonate 3 parts, sodium silicate 6 parts, aluminum sulfate 4 parts and redispersible glue powder 5 parts.

[0049] Embodiment 4:

[0050] The embodiment provides a preparation method of maintenance-free concrete, and the specific steps are as follows:

[0051] Step 1) binding steel bars, the reinforcing bars also have porous steel pipes with a volume fraction of 30% of ordinary steel bars, and the porous steel pipes are filled with saturated water-washed sand with a particle size of less than 2mm;

[0052] Step 2) erecting a concrete heat insulation template;

[0053] Step 3) pouring concrete, the aggregate in the concrete needs clean surface before use, and spraying 0.1% concentration of silica sol, the spraying amount of each ton of aggregate is 0.5kg; the concrete also contains 3kg / m 3 of fiber tube, 2kg / m 3 of cellulose and 1kg / m 3 of cellulose fiber; the fiber tube is a porous fiber tube, the cellulose fiber needs to be boiled at high temperature; the fiber tube and the cellulose fiber need to be immersed into a composite ion solution with a mass fraction of 0.5% before use, the composite ion solution is composed of 40% sodium silicate, 24% sodium carbonate, 15% sodium hydroxide, 15% potassium hydroxide, 3% urea and 3% triethanolamine;

[0054] Step 4) after the concrete is poured, initial setting and before final setting, spray 150g of concrete protective layer material on each square of concrete surface, and then perform second time troweling and polishing; the concrete protective layer material comprises ordinary Portland cement 80 parts, sulphoaluminate cement 20 parts, limestone powder 20 parts, quartz sand powder 20 parts, sodium carbonate 5 parts, sodium silicate 5 parts, aluminum sulfate 5 parts, and redispersible glue powder 4 parts.

[0055] Performance detection

[0056] Table 1 is the performance evaluation index of the present application, and the test of the mechanical properties of the concrete is performed according to the standard GB / T50081-2002; the dry shrinkage test is performed according to the standard GB / T50082-2009 "Standard for Testing Methods of Long-term Performance and Durability of Ordinary Concrete", and the deformation of the test piece is measured by using a micrometer during the test.

[0057] The reference concrete mixture ratio is as follows: P·O42.5 cement 320 kg, mineral powder 60 kg, fly ash 60 kg, sand 700 kg, stone 1150 kg, water 160 kg, and polycarboxylic acid water reducing agent 5 kg.

[0058] The concrete of the comparative example is prepared by using the above concrete mixture ratio and the conventional construction method. The fiber tube, the cellulose, and the cellulose fiber in the embodiments 1-4 are added by replacing the sand with the same mass, and the construction method of the present application is used. The concrete in the comparative example and the embodiments 1-4 is demolded after 3 days, and is maintained under the natural conditions in autumn. In addition, for the convenience of comparison, the performance of the concrete in the comparative example under the standard curing conditions is also tested.

[0059]

[0060] As shown in Table 1, the strength of the maintenance-free concrete can be significantly improved, and the dry shrinkage of the concrete can be reduced after the present application is used; compared with the standard curing concrete, the prepared concrete of the present application has a smaller decrease in compressive strength and a similar volume deformation rate.

[0061] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent transformation or modification made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A method for producing a maintenance-free concrete, characterized by, It comprises the following steps: S1. Binding the steel bars, in which the perforated steel pipes filled with water-saturated sand or water-absorbing resin are arranged; S2. Setting up the concrete heat insulation template; S3. Spraying the silica sol or saturated calcium hydroxide solution on the surface of the concrete aggregate, and pouring the concrete; the concrete contains the fiber tube, cellulose and cellulose fiber; S4. Spraying the concrete protective layer material on the surface of the concrete after the pouring and before the final setting after the initial setting, and then performing the second troweling and polishing; the protective layer material comprises ordinary portland cement 50-100 parts by weight, sulphoaluminate cement 20-50 parts by weight, limestone powder 10-30 parts by weight, quartz sand powder 10-30 parts by weight, sodium carbonate 1-10 parts by weight, sodium silicate 1-10 parts by weight, aluminum sulfate 1-10 parts by weight, and redispersible glue powder 1-10 parts by weight.

2. The method of producing a maintenance-free concrete according to claim 1, characterized in that: In S3, the fiber tube is a perforated fiber tube; the cellulose fiber needs to be boiled at high temperature; before use, the fiber tube and the cellulose fiber need to be soaked in a composite ion solution with a mass fraction of 0.05-1%; the composite ion solution is composed of 10-40% sodium silicate, 10-30% sodium carbonate, 5-30% sodium hydroxide, 5-30% potassium hydroxide, 1-10% urea and 1-10% triethanolamine by weight.

3. The method of producing a maintenance-free concrete according to claim 2, characterized in that: The content of the fiber tube in the concrete is 0.5-5 kg / m 3 The content of the cellulose in the concrete is 0.5-2 kg / m 3 The content of the cellulose fiber in the concrete is 0.5-5 kg / m 3 .

4. The method of making a no-maintenance concrete according to claim 1, characterized in that: In S1, the volume of the perforated steel pipe is 10-40% of the volume of the steel bar.

5. The method of making a no-maintenance concrete according to claim 1, wherein: In S1, the particle size of the water-saturated sand or water-absorbing resin is less than 2mm.

6. The method of making a no-maintenance concrete according to claim 1, wherein: In S3, the silica sol is a silica sol with a concentration of 0.01-1%.

7. The method of making a no-maintenance concrete according to claim 1, wherein: In S3, the spraying amount of the silica sol or saturated calcium hydroxide solution is 0.5-2kg of silica sol or saturated calcium hydroxide solution per ton of concrete aggregate.

8. The method of making a maintenance-free concrete according to claim 1, characterized in that: In S4, the spraying amount of the protective layer material is 50-200g of protective layer material per square meter of concrete surface.

9. The method of producing a no-maintenance concrete according to any one of claims 1 to 8, characterized in that: In S3, the concrete aggregate needs to be cleaned before use.

Images