Background
Along with the development of cities, the urban road surface is a great pressure for water supply and drainage after heavy rain, the landscape of urban oceans often appears, the reason is that urban municipal pipe networks are more and more complicated, the drainage is not timely enough, and the drainage effect is poor. In recent years, foam concrete is more popular in urban water supply and drainage, the foam concrete is a novel light heat-insulating material containing a large number of closed air holes, which is formed by fully foaming a foaming agent in a mechanical mode through a foaming system of a foaming machine, uniformly mixing foam and cement slurry, then carrying out cast-in-place construction or mould forming through a pumping system of the foaming machine, and carrying out natural curing. However, the water-permeable foam concrete has high porosity, so that the connection between hole walls is not tight, and the concrete strength is often low.
China is a textile consumption market which is rapidly increased in the world, is also the largest world country for producing textile and clothing and export countries, generates a large amount of waste textiles such as old clothes every year, however, at present, China is still in a primary stage in the aspect of recycling of the waste textiles, the recycling rate of the waste textiles is low, and particularly a recycling system is urgently to be perfected. The total amount of fiber processing in China per year reaches more than 5000 million tons, wherein the proportion of chemical fibers reaches about 84%, the specific gravity of terylene in the existing chemical fibers is about 80%, the social storage capacity of waste chemical fiber textiles in China is nearly 4 hundred million tons, the waste materials in the production and processing processes are more than 400 million tons per year, the used and scrapped fiber products are more than 800 million tons per year, and the resource recovery rate is less than 10%, so that the utilization level and the specific gravity of the waste textiles in China are improved as soon as possible, the huge environmental pressure caused by the undegradability of the waste textiles can be solved, and the contradiction that the chemical fiber raw materials in China are in short supply of petroleum resources can be relieved and even solved.
The terylene fabrics in the chemical fiber can be widely applied because of the advantages that other fabrics cannot replace the terylene fabrics, such as: (1) the strength of the fiber is high, the strength of short fibers is 2.6-5.7 cN/dtex, and the strength of high-strength fibers is 5.6-8.0 cN/dtex; (2) the elasticity is super strong, the elasticity is close to that of wool, the wool can be almost completely recovered when the wool is stretched by 5-6%, and the elastic modulus is 22-141 cN/dtex; (3) the heat resistance is good; (4) the light resistance is good; (5) the wear resistance is good; (6) the chemical resistance is good, and the damage degree of acid and alkali is not large; therefore, if the waste polyester textiles can be applied to concrete, not only is the secondary utilization of wastes realized, but also the problem of environmental pollution caused by the waste polyester textiles is effectively solved.
Although the terylene textile has the advantages, the terylene textile has certain defects, the terylene is the trade name of the polyethylene terephthalate fiber, and because the linear macromolecules of the terylene have a symmetrical benzene ring structure, good linearity and a stereo regular macromolecule chain structure, two ends of the molecule of the terylene textile are only provided with one hydroxyl respectively, no other hydrophilic groups are provided, the molecule chain structure is compact, the crystallinity and the orientation degree are both high, and the terylene textile is a typical hydrophobic fiber, so the terylene textile has poor hygroscopicity and the moisture absorption rate of only 0.4 percent, and if the terylene textile is applied to concrete in a large amount, the terylene textile brings adverse effect to municipal drainage.
Disclosure of Invention
Aiming at the technical defects, the invention aims to provide a recycled aggregate concrete and a preparation method and application thereof.
In order to solve the technical problems, the invention adopts the following technical scheme:
the waste fiber recycled concrete is prepared from the following raw materials in parts by weight: 1080 portions of coarse aggregate 953-.
Preferably, the raw material also comprises 13-15 parts of polyacrylonitrile fiber, and the length of the polyacrylonitrile fiber is 5-10 mm.
Preferably, the cementing material is composed of the following raw materials in percentage by mass: 74-80% of cement, 10-14% of fly ash and 10-13% of gypsum; the cement is P.O42.5 portland cement, and the fly ash is II-grade F-type low-calcium fly ash.
Preferably, the foaming agent is composed of the following raw materials in percentage by mass: 50-65% of foaming agent, 20-27% of foam stabilizer and 8-30% of air entraining agent.
Preferably, the modified fiber is prepared according to the following steps:
s1, mixing the waste polyester textiles with the swelling agent, stirring for 0.5-1h at 70-85 ℃, and cleaning to obtain swelling textiles;
wherein the mass ratio of the waste terylene textile to the swelling agent is 100-150: 4-8;
s2, placing the swollen textile obtained in the step S1 in an emulsifier aqueous solution, adding a hydrophilic finishing agent, stirring at 80-100 ℃ for 1.5-4h, and drying to obtain a modified textile;
wherein the ratio of the mass of the swollen textile to the volume of the emulsifier and the mass of the hydrophilic finishing agent is 100-150 g: 5-10 mL: 6-10 g;
s3, crushing the modified textile in the step S2 to obtain modified fibers, wherein the length of the modified fibers is 1.5-4 cm.
Preferably, the swelling agent of step S1 is chlorobenzene or m-cresol or a mixture of the two.
Preferably, the emulsifier in step S2 is AOE9, tween 20, tween 60 or tween 80, and the hydrophilic treatment agent is a polysiloxane hydrophilic treatment agent, a polyurethane hydrophilic treatment agent, a polyacrylate hydrophilic treatment agent or a chitosan hydrophilic treatment agent.
The invention also protects a preparation method of the waste fiber recycled concrete, which comprises the following steps:
(1) weighing: weighing the following raw materials in parts by weight: 1080 parts of coarse aggregate 953-;
(2) mixing and uniformly stirring coarse aggregate, fine aggregate, a cementing material, a foaming agent, a water reducing agent, modified fiber, slag and water, quickly paving to a construction surface, and curing to form the formed waste fiber recycled concrete.
Preferably, 13-15 parts of polyacrylonitrile fiber is also weighed in the step (1) and added into the step (2).
The invention also protects the application of the waste fiber recycled concrete in preparing the road engineering water permeable material.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention carries out technical modification on waste polyester textiles, and the specific method comprises the following steps: the waste polyester textiles are swelled by adopting the swelling agent firstly, so that the polyester textiles with compact structures are loosened, and then the other modifiers are promoted to diffuse into the polyester textiles, so that the attachment areas of the other modifiers are increased, the higher moisture absorption rate is obtained, and the moisture absorption of the waste polyester textiles is facilitated under the action of the swelling agent, and the result shows that the moisture absorption rate is obviously increased under the action of chlorobenzene or m-cresol, and is increased to 6-7% from the moisture absorption rate of 0.4-0.5%.
After swelling, performing hydrophilic treatment on the swollen textile, wherein the specific treatment method comprises the following steps: the swelling textile is added into the emulsifier water solution, and the emulsifier has both oleophilic groups and hydrophilic groups, so that the emulsifier promotes the mixing of the swelling textile and the hydrophilic treatment agent, and the hydrophilic treatment agent is uniformly and firmly covered on the surface of the polyester fiber to form a hydrophilic film, thereby improving the hydrophilic performance of the polyester; and then in the heating process, the co-crystallization phenomenon is generated between the hydrophilic treatment agent and the surface of the terylene, so that the surface of the waste terylene textile is rich in hydrophilic groups, and the aim of moisture absorption is fulfilled.
2. The modified fiber is applied to concrete, the concrete comprises coarse aggregate, fine aggregate, a cementing material, a foaming agent, a water reducing agent, modified fiber, slag and water, the cementing material and the modified fiber are used for improving the strength of the concrete, the foaming agent and the slag are used for forming a large number of closed air holes to facilitate water permeation, and meanwhile the modified fiber has a water absorption effect, so that the excellent water absorption and water permeation effects are realized while the mechanical property of the concrete is ensured.
In addition, the cementing material comprises gypsum, slag and cement, and the hydration products of the gypsum, the slag and the cement form a C-H-S amorphous gel structure, so that the mechanical property of the concrete is improved.
Detailed Description
The following detailed description of specific embodiments of the invention is provided, but it should be understood that the scope of the invention is not limited to the specific embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. The experimental methods described in the examples of the present invention are all conventional methods unless otherwise specified.
Example 1
A preparation method of waste fiber recycled concrete comprises the following steps:
(1) preparing modified fibers:
s1, dissolving 100g of waste polyester textiles and 4g of chlorobenzene swelling agent into 100mL of water, stirring for 1 hour at 70 ℃, and cleaning to obtain swelling textiles;
s2, adding 100g of the swollen textile obtained in the step S1 into an aqueous solution containing 5mL of Tween 20, adding 10g of polysiloxane hydrophilic treatment agent, stirring at 80 ℃ for 4h, and drying to obtain a modified textile;
s3, crushing the modified textile obtained in the step S2 to obtain modified fibers, wherein the length of the modified fibers is 1.5 cm;
(2) weighing: weighing the following raw materials in parts by weight: 953 parts of coarse aggregate, 813 parts of fine aggregate, 340 parts of cementing material, 6 parts of foaming agent, 6.8 parts of water reducing agent, 11 parts of modified fiber, 40 parts of slag and 200 parts of water for later use;
the cementing material is composed of the following raw materials in percentage by mass: 80% of cement, 10% of fly ash and 10% of gypsum;
the foaming agent is prepared from the following raw materials in percentage by mass: 65% of foaming agent, 27% of foam stabilizer and 8% of air entraining agent;
(3) mixing and uniformly stirring coarse aggregate, fine aggregate, a cementing material, a foaming agent, a water reducing agent, modified fiber, slag and water, quickly paving to a construction surface, and curing to form the formed waste fiber recycled concrete.
Example 2
A preparation method of waste fiber recycled concrete comprises the following steps:
(1) preparing modified fibers:
s1, dissolving 120g of waste polyester textiles and 6g of m-cresol swelling agent into 100mL of water, stirring at 80 ℃ for 45min, and cleaning to obtain swollen textiles;
s2, adding 120g of the swollen textile obtained in the step S1 into an aqueous solution containing 8mL of Tween 60, adding a polyurethane hydrophilic treatment agent, stirring at 90 ℃ for 2.5h, and drying to obtain a modified textile;
s3, crushing the modified textile obtained in the step S2 to obtain modified fibers, wherein the length of the modified fibers is 3 cm;
(2) weighing: weighing the following raw materials in parts by weight: 1000 parts of coarse aggregate, 800 parts of fine aggregate, 400 parts of cementing material, 5 parts of foaming agent, 7 parts of water reducing agent, 12 parts of modified fiber, 38 parts of slag and 230 parts of water for later use;
the cementing material is composed of the following raw materials in percentage by mass: 75% of cement, 12% of fly ash and 13% of gypsum;
the foaming agent is prepared from the following raw materials in percentage by mass: 60% of foaming agent, 20% of foam stabilizer and 20% of air entraining agent;
(3) mixing and uniformly stirring coarse aggregate, fine aggregate, a cementing material, a foaming agent, a water reducing agent, modified fiber, slag and water, quickly paving to a construction surface, and curing to form the formed waste fiber recycled concrete.
Example 3
A preparation method of waste fiber recycled concrete comprises the following steps:
(1) preparing modified fibers:
s1, dissolving 150g of waste polyester textiles and 8g of mixed swelling agent of chlorobenzene and m-cresol into 150mL of water, stirring at 85 ℃ for 0.5h, and cleaning to obtain swelling textiles;
s2, adding 150g of the swollen textile obtained in the step S1 into 10mL of AOE 9-containing aqueous solution, adding 6g of chitosan hydrophilic treatment agent, stirring at 100 ℃ for 1.5h, and drying to obtain a modified textile;
s3, crushing the modified textile obtained in the step S2 to obtain modified fibers, wherein the length of the modified fibers is 4 cm;
(3) weighing: weighing the following raw materials in parts by weight: 1080 parts of coarse aggregate, 728 parts of fine aggregate, 490 parts of cementing material, 3 parts of foaming agent, 8.33 parts of water reducing agent, 15 parts of modified fiber, 35 parts of slag and 250 parts of water for later use;
the cementing material is composed of the following raw materials in percentage by mass: 74% of cement, 13% of fly ash and 13% of gypsum;
the foaming agent is prepared from the following raw materials in percentage by mass: 50% of foaming agent, 20% of foam stabilizer and 30% of air entraining agent;
(3) mixing and uniformly stirring coarse aggregate, fine aggregate, a cementing material, a foaming agent, a water reducing agent, modified fiber, slag and water, quickly paving to a construction surface, and curing to form the formed waste fiber recycled concrete.
Example 4
A preparation method of waste fiber recycled concrete comprises the following steps:
(1) preparing modified fibers:
s1, dissolving 120g of waste polyester textiles and 6g of m-cresol swelling agent into 100mL of water, stirring at 80 ℃ for 45min, and cleaning to obtain swollen textiles;
s2, adding 120g of the swollen textile obtained in the step S1 into an aqueous solution containing 8mL of Tween 60, adding a polyurethane hydrophilic treatment agent, stirring at 90 ℃ for 2.5h, and drying to obtain a modified textile;
s3, crushing the modified textile obtained in the step S2 to obtain modified fibers, wherein the length of the modified fibers is 3 cm;
(2) weighing: weighing the following raw materials in parts by weight: 1000 parts of coarse aggregate, 800 parts of fine aggregate, 400 parts of cementing material, 5 parts of foaming agent, 7 parts of water reducing agent, 12 parts of modified fiber, 38 parts of slag, 230 parts of water and 14 parts of polyacrylonitrile fiber for later use;
the cementing material is composed of the following raw materials in percentage by mass: 75% of cement, 12% of fly ash and 13% of gypsum;
the foaming agent is prepared from the following raw materials in percentage by mass: 60% of foaming agent, 20% of foam stabilizer and 20% of air entraining agent;
(3) mixing and uniformly stirring coarse aggregate, fine aggregate, a cementing material, a foaming agent, a water reducing agent, modified fiber, polyacrylonitrile fiber, slag and water, quickly paving the mixture on a construction surface, and curing the mixture to form the formed waste fiber recycled concrete.
Comparative example 1
The same procedure as in example 2 was followed except that no modified fiber was added.
The waste fiber recycled concrete which ensures the mechanical property of the concrete and simultaneously realizes excellent water absorption and water permeation effects is prepared in the examples 1 to 3 of the invention, the effects are parallel, the concrete prepared in the examples 1 to 3 and the comparative examples 1 and 4 is contrastively analyzed, a standard test block of 150mm multiplied by 150mm is formed by a flat plate vibrator, the test is carried out after 28 days of maintenance, and the test scheme of the compressive strength and the flexural strength is carried out according to the standard GB/T50081 of the test method of the mechanical property of the common concrete; the porosity and the water permeability coefficient refer to a gravimetric method and a water head determination method introduced in permeable concrete and application technology thereof (edited by Song Zhongnan et al, Chinese architecture industry Press, 2011.8); specific results are shown in table 1:
TABLE 1 comparison of Properties of waste fiber recycled concrete
Compared with the embodiment 2, the embodiment 4 has the advantages that the polyacrylonitrile fiber is added on the basis of the embodiment 2, the mechanical property of the waste fiber recycled concrete is effectively improved after the polyacrylonitrile fiber and the cementing material are blended, but the water permeability coefficient and the porosity are both reduced to a certain degree, but the water permeability coefficient of the embodiment 4 is more than or equal to 0.5, the porosity is 11-17, the standard of the pervious concrete is met, and the excellent mechanical property is realized, and the result shows that the waste fiber recycled concrete with better mechanical property and water permeability is prepared after the polyacrylonitrile fiber is added.
Compared with the examples 1 to 3, the water permeability coefficient, the porosity, the compressive strength and the flexural strength of the recycled concrete are not greatly different, and the results show that the prepared recycled concrete of the waste fibers has excellent water permeability and mechanical properties;
compared with the comparative example 1, in the example 2, after the modified fiber is not added, the water permeability coefficient and the porosity are not obviously improved, but the mechanical property is obviously reduced, which indicates that the water permeability is influenced before and after the modified fiber is added, but the influence is not large, namely, the polyester fiber has certain water absorption in concrete due to the modification, so that the water permeability on the concrete is not obvious any more; and because of not adding modified fiber, lead to producing huge influence to mechanical properties, the result has also shown that this application has carried out effective modification to polyester fiber to regard it as the addition material and be used for promoting the mechanical properties of concrete.
And (3) durability test:
placing the standard test block in a composite salt solution to carry out a dry-wet alternation test, wherein the dry-wet alternation operation comprises the following steps: na (Na)2SO4-MgSO4Soaking in NaCl complex salt solution for 15h, airing indoors for 1h, drying at 60 ℃ for 7h, and cooling indoors for 1h, wherein the total time is 24 h; testing the pH value of the compound salt solution by using a handheld pH meter every 7 days, adjusting the pH value of the solution to 7.0 +/-0.5 by using analytically pure concentrated sulfuric acid, and replacing the solution every 30 days; after the standard test block is dried and wetted for 180 times alternately, the standard test block is dried for 48 hours at the temperature of 60 ℃, the dynamic elastic modulus, the quality, the compressive strength and the splitting tensile strength of the standard test block are tested again, and the relative value of each index is calculated; the durability index of the waste fiber recycled concrete is shown in table 2:
TABLE 2 durability index of waste fiber recycled concrete
The result shows that compared with the corresponding physical and mechanical performance indexes of the standard test block of the non-eroded recycled concrete, the waste fiber recycled concrete eroded for a long time, the mechanical property and the relative dynamic elastic modulus of the material have certain loss, after the dry-wet alternation is carried out for 180 times, the mechanical properties of the waste fiber recycled concrete prepared in the embodiment 2 and the embodiment 4 of the invention are reduced, but the performance is not obviously reduced, which shows that the waste fiber recycled concrete prepared in the embodiment 2 and the embodiment 4 of the invention has better corrosion resistance which is obviously superior to that of the comparative example 1, this also shows that the mechanical properties of the concrete are improved after the modified fiber and the polyacrylonitrile fiber are added, and the corrosion resistance of the concrete is improved, which shows that the modified fiber and the polyacrylonitrile fiber have positive effects on the corrosion resistance of the waste fiber recycled concrete.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.