CN116161917A

CN116161917A - Special concrete with high water permeability

Info

Publication number: CN116161917A
Application number: CN202310443979.9A
Authority: CN
Inventors: 冯涛; 许银; 景洪刚
Original assignee: Zibo Taikun Concrete Co ltd
Current assignee: Zibo Taikun Concrete Co ltd
Priority date: 2023-04-24
Filing date: 2023-04-24
Publication date: 2023-05-26
Anticipated expiration: 2043-04-24
Also published as: CN116161917B

Abstract

The application belongs to the technical field of special concrete, and particularly discloses special concrete with high water permeability. The special concrete with high water permeability comprises the following raw materials in parts by weight: 650-750 parts of coarse aggregate, 300-400 parts of fine aggregate, 200-300 parts of cement, 150-200 parts of water, 30-60 parts of fly ash, 15-45 parts of modified ceramsite, 5-10 parts of water reducer, 10-30 parts of reinforced polypropylene fiber and 150-300 parts of crushed stone. The reinforced polypropylene fiber, the fly ash and the modified ceramsite are matched for use, so that the mechanical property, the cracking resistance and the wear resistance of the concrete are improved, the service performance of the pavement is improved, accumulated water is discharged rapidly after raining, the service performance of the pavement is improved, and the probability of repairing the pavement is reduced.

Description

Special concrete with high water permeability

Technical Field

The application relates to the technical field of special concrete, in particular to special concrete with high water permeability.

Background

The special concrete is concrete with special purpose made of new materials, industrial waste or new technology. Such as lightweight aggregate concrete, fiber reinforced concrete, polymer concrete, water permeable concrete, and the like. The permeable concrete is usually used for processing permeable concrete products such as permeable bricks and the like, and is usually applied to paving urban road surfaces or constructing road surfaces in parks.

Asphalt concrete or cement concrete paved road surfaces often have ponding phenomenon in rainy days, and water permeable bricks made of water permeable concrete are used for paving, so that water can be quickly permeated into the ground, the ponding phenomenon of the road surfaces is relieved, and the possibility of wetting pedestrians and shoes is reduced.

The existing permeable concrete products mainly comprise granules with tiny through holes, such as cement, coarse aggregate, fine aggregate, ceramsite, waste ceramic tile, kaolin and the like, and the granules introduce the through holes into a concrete product system, so that water can permeate, and accumulated water of a pavement can be quickly discharged.

However, the water-permeable concrete is added with a plurality of granular materials with tiny through holes, so that the strength of the water-permeable concrete product is not high, the problems of easy breakage, short pot life and the like of the subsequently paved road surface are caused, the road surface is further required to be repaired, traffic is influenced, and complex repair work is caused.

Disclosure of Invention

In order to solve the problem of poor strength of water-permeable concrete, the application provides special concrete with high water permeability.

The application provides special concrete with high water permeability, which adopts the following technical scheme:

the special concrete with high water permeability comprises the following raw materials in parts by weight: 650-750 parts of coarse aggregate, 300-400 parts of fine aggregate, 200-300 parts of cement, 150-200 parts of water, 30-60 parts of fly ash, 15-45 parts of modified ceramsite, 5-10 parts of water reducer, 10-30 parts of reinforced polypropylene fiber and 150-300 parts of crushed stone.

By adopting the technical scheme, coarse aggregate and broken stone are piled into a compact framework in concrete, the framework function is realized, the stability of the concrete is ensured, fine aggregate is filled in the concrete, the fine aggregate and cement are mixed into mortar to fill the gaps of the framework, the fine aggregate cuts and blocks the cement mortar, so that the shrinkage stress of the cement mortar is dispersed, the probability of cracking of the structure due to the shrinkage of the cement mortar is further relieved, and the concrete can form a stable structure; the addition of the water reducer can improve the fluidity of the concrete, so that the structure of the concrete is more stable, and the strength of the concrete is improved.

The fly ash can play an active role in concrete, gaps between cement and coarse and fine aggregates can be smaller, the effect of filling is achieved, the structural density of the concrete is improved, a large number of mutually communicated pores exist in the modified ceramsite, the pores enable the ceramsite to have good water absorption capacity and air permeability, after rain, rainwater can quickly infiltrate into the ground through the concrete, the pressure of a road surface is effectively relieved, no water accumulation on the road surface is guaranteed, and the fly ash has a porous structure and spherical particle size, has good permeability and good fluidity in a loose state, is further beneficial to the infiltration of the rainwater, is loaded on the surface and in part of the pores of the modified ceramsite, the phenomenon that the stress of the ceramsite is concentrated when the ceramsite bears external load is improved, the mechanical property of the concrete is improved, and when the modified ceramsite is formed in a vibration mode, the friction among particles is small, the particles are closely arranged, and the mechanical property of the concrete is improved.

The reinforced polypropylene fiber has higher strength, impact resistance and wear resistance, can effectively prevent shrinkage crack phenomenon of concrete, is uniformly dispersed in the concrete and is mixed with the fly ash and the modified ceramsite, so that the modified ceramsite and the fly ash are more tightly bonded, the cracking phenomenon of the concrete is further inhibited, the water permeability of the concrete is ensured, the mechanical property, the cracking resistance and the wear resistance of the concrete are increased, the service performance of a pavement is further enhanced, and the probability of repairing the pavement is reduced.

Preferably, the preparation method of the reinforced polypropylene fiber comprises the following steps:

(1) Immersing polypropylene fibers into a dilute hydrochloric acid solution, stirring for 10-15min at 60-70 ℃, and then flushing with deionized water to be neutral for later use;

(2) Putting the polypropylene fiber treated in the step (1) into a modifying solution, performing ultrasonic treatment at 80-90 ℃ for 25-35min, and then flushing with deionized water to be neutral for later use;

the modified liquid comprises the following raw materials in parts by weight: nano silicon dioxide, N-dimethylacetamide, chitosan, magnesium stearate, a silane coupling agent and deionized water;

(3) And (3) drying the polypropylene fiber treated in the step (2) at the temperature of 120-150 ℃ for 5-10h to obtain the reinforced polypropylene fiber.

By adopting the technical scheme, the polypropylene fiber is immersed into the dilute hydrochloric acid solution, and the dilute hydrochloric acid carries out micro corrosion on the surface of the polypropylene fiber, so that a large amount of microporation is formed on the surface of the polypropylene fiber, the surface of the fiber is roughened, the specific surface area of the fiber is increased, and the adsorption multiplying power of the fiber is further improved. Then the polypropylene fiber is put into the modified liquid for treatment, so that the structural strength, impact resistance and wear resistance of the polypropylene fiber are improved, nano silicon dioxide has higher strength and compression resistance, nano silicon dioxide is loaded on the outer surface and in micropores of the polypropylene fiber, the strength of the polypropylene fiber is further improved, chitosan is a macromolecular spiral structure, the chitosan is coated on the outer surfaces of the polypropylene fiber and the nano silicon dioxide, the connectivity between the nano silicon dioxide and the fiber is further improved, the nano silicon dioxide is more stably loaded on the outer surfaces of the fiber, magnesium stearate has better lubrication and flow-assisting effects, the fluidity of the nano silicon dioxide is improved, the nano silicon dioxide is uniformly attached on the surface of the fiber, meanwhile, the viscosity of the chitosan is reduced, excessive chitosan is prevented from being loaded on the surface of the fiber, and the cohesiveness between the chitosan and the fiber is further reduced.

In the subsequent preparation process of special concrete, the reinforced polypropylene fiber not only increases the strength, cracking resistance and impact resistance of the concrete, but also has the effects of high physical filling effect and micro-cracks and gaps filled by chemical activity on the surface of the fiber, so that the reinforced polypropylene fiber is more tightly connected with modified ceramsite, fly ash and the like, and the compactness of the nano structure of the concrete is further improved, thereby improving the mechanical property and durability of the concrete, ensuring that the concrete has better water permeability and improving the mechanical properties such as cracking resistance, impact resistance, strength and the like of the concrete.

Preferably, the mass ratio of the nano silicon dioxide to the chitosan to the magnesium stearate is 1:2-6:0.5-0.8.

By adopting the technical scheme, the mass ratio of the nano silicon dioxide, the chitosan and the magnesium stearate is controlled within a certain range, the reinforced polypropylene fiber with higher structural strength, impact resistance and wear resistance is obtained, the nano silicon dioxide increases the strength of the fiber, the chitosan enables the nano silicon dioxide to be loaded on the surface of the fiber, the magnesium stearate enables the nano silicon dioxide to be uniformly attached on the surface of the fiber, meanwhile, the magnesium stearate reduces the viscosity of the chitosan, excessive chitosan is prevented from being loaded on the surface of the fiber, the cohesiveness between the chitosan and the fiber is further reduced, the nano silicon dioxide, the chitosan and the magnesium stearate have a synergistic effect, and the comprehensive performance of the fiber is improved.

Preferably, the preparation method of the modified ceramsite comprises the following steps:

(1) Soaking ceramsite in citric acid solution, washing with water to neutrality, and calcining at 900-1100 deg.C for 2-3 hr;

(2) Dispersing the ceramsite treated in the step (1) in a silane coupling agent solution, soaking for 1-2h, then adding nano titanium dioxide, stirring for 2-3h, and drying to obtain the modified ceramsite.

By adopting the technical scheme, the ceramsite is soaked in the citric acid, the citric acid is used for cleaning and removing organic impurities in the ceramsite, the pores and pore channels of the ceramsite are cleaned, the ventilation and water permeability of the ceramsite are maintained, then the ceramsite is calcined at high temperature, the organic impurities in the ceramsite are further removed, and meanwhile, the pores and the pore channels in the ceramsite are enlarged, so that the ventilation and water permeability of the ceramsite are improved.

The nano titanium dioxide is loaded in part of pores and pore channels of the modified ceramsite, so that the strength and compression resistance of the ceramsite are improved, the silane coupling agent is added to enhance the combination between the ceramsite and the nano titanium dioxide on one hand, and on the other hand, a certain dispersing effect is achieved, so that the nano titanium dioxide is uniformly dispersed on the surface of the ceramsite, the pores and pore channels of the ceramsite are not completely blocked, the water permeability of the ceramsite is further ensured, the subsequent modified ceramsite is applied to special concrete, the water permeability of the concrete is ensured, and meanwhile, the mechanical properties such as the strength of the concrete are improved.

Preferably, the mass ratio of the ceramsite to the nano titanium dioxide to the silane coupling agent solution is 1:0.2-0.5:3-5.

By adopting the technical scheme, the mass ratio of the ceramsite, the nano titanium dioxide and the silane coupling agent solution is controlled, so that the modified ceramsite with higher strength is obtained, the ceramsite, the nano titanium dioxide and the silane coupling agent solution have a synergistic effect, the nano titanium dioxide increases the mechanical property of the ceramsite, the silane coupling agent enables the nano titanium dioxide to be uniformly dispersed, and meanwhile, the silane coupling agent increases the binding force of the ceramsite and the nano titanium dioxide, so that the strength of the ceramsite is improved.

Preferably, the fly ash is pretreated by the following steps: grinding and sieving the fly ash, dispersing the fly ash in oxalic acid solution, soaking for 20-30min, washing with water to neutrality, calcining for 10-30min at 300-500 ℃, dispersing the fly ash in mixed solution, soaking for 30-40min, filtering, and drying to obtain treated fly ash, wherein the mixed solution is prepared by dispersing wood fiber powder in ethanol solution.

By adopting the technical scheme, the fly ash is dispersed in the oxalic acid solution, the activity of the fly ash is improved, organic impurities in the fly ash are removed, the specific surface area of the fly ash is increased, the adsorption effect of the fly ash is enhanced, the fly ash is calcined at a certain temperature, the specific surface area and the activity of the fly ash are further increased, the follow-up fly ash is dispersed in the mixed solution, the wood fiber powder can be dispersed in the pores of the fly ash, the structural strength of the fly ash is increased, in addition, the wood fiber has a very strong crosslinking function and is mixed with the fly ash, the connectivity among fly ash particles is increased, a three-dimensional net structure is formed, the follow-up fly ash is applied to special concrete, the cohesive force of each component of the concrete is increased, the connection between the modified ceramsite and the reinforced polypropylene fiber is facilitated to be more compact, and the mechanical property and the cracking resistance of the concrete are further increased.

Preferably, the crushed stone comprises 100-200 parts of crushed stone with the particle size of 15-25mm and 50-100 parts of crushed stone with the particle size of 20-30 mm.

Through adopting above-mentioned technical scheme, the rubble includes two kinds of rubble that particle diameter scope is different, and the particle diameter is different to help the follow-up more even of mixing in concrete, makes the structure of concrete more compact, improves the structural strength and the mechanical stability of concrete.

Preferably, the water reducing agent is a polycarboxylate water reducing agent.

In summary, the application has the following beneficial effects:

1. coarse aggregate and rubble pile in this application become inseparable framework in concrete, have guaranteed the stability of concrete, and fine aggregate plays the filling effect in concrete, and fine aggregate mixes into the space that the framework was filled to mortar with cement, and fine aggregate cuts apart cement mortar and blocks, makes cement mortar's shrinkage stress disperse, and then has alleviateed the probability that the structure ftractures because of cement mortar's shrink, promotes that concrete can form stable structure.

2. The fly ash in this application can play active effect in concrete, can make the gap between cement and the thick and thin aggregate become littleer, has played the effect of filling, makes the structural density of concrete improve, and inside a large amount of holes that communicate each other that exist of modified haydite, these holes make the haydite have better ability and the gas permeability that absorb water, after raining, can make the rainwater permeate underground through concrete rapidly, effectively alleviate the pressure on road surface, guarantee that the road surface does not have ponding.

3. The reinforced polypropylene fiber has higher strength, impact resistance and wear resistance, can effectively prevent shrinkage crack phenomenon of concrete, is uniformly dispersed in the concrete and is mixed with the fly ash and the modified ceramsite, so that the modified ceramsite and the fly ash are more tightly bonded, the cracking phenomenon of the concrete is further inhibited, the water permeability of the concrete is ensured, the mechanical property, the cracking resistance and the wear resistance of the concrete are increased, the service performance of a pavement is further enhanced, and the probability of repairing the pavement is reduced.

Detailed Description

The present application is described in further detail below with reference to examples.

The raw materials used in examples and comparative examples are all commercially available, and the water reducing agent is a polycarboxylate water reducing agent.

PREPARATION EXAMPLE 1-1

The preparation method of the reinforced polypropylene fiber comprises the following steps:

(1) 1kg of polypropylene fiber is immersed into 10L of dilute hydrochloric acid solution with mass fraction of 5%, stirred for 12min at 65 ℃, and then washed to be neutral by deionized water for standby;

(2) Putting the polypropylene fiber treated in the step (1) into 5L of modified liquid, performing ultrasonic treatment at the temperature of 85 ℃ for 30min, and then flushing with deionized water to be neutral for later use;

wherein the modifying liquid comprises the following raw materials by weight: 15kg of nano silicon dioxide, 2kg of N, N-dimethylacetamide, chitosan, magnesium stearate, 9kg of silane coupling agent and 150kg of deionized water; the mass ratio of the nano silicon dioxide to the chitosan to the magnesium stearate is 1:4:0.7.

(3) And (3) drying the polypropylene fiber treated in the step (2) at the temperature of 140 ℃ for 8 hours to obtain the reinforced polypropylene fiber.

PREPARATION EXAMPLES 1-2

The difference from preparation example 1-1 is that step (2) was not performed.

Preparation examples 1 to 3

The difference from preparation example 1-1 is that in the step (2), chitosan was not added to the modified liquid.

Preparation examples 1 to 4

The difference from preparation example 1-1 is that magnesium stearate is not added to the modified liquid in step (2).

Preparation examples 1 to 5

The difference from preparation example 1-1 is that the mass ratio of nano silicon dioxide, chitosan and magnesium stearate is 1:2:0.5.

Preparation examples 1 to 6

The difference from preparation example 1-1 is that the mass ratio of nano silicon dioxide, chitosan and magnesium stearate is 1:6:0.8.

Preparation examples 1 to 7

The difference from preparation example 1-1 is that the mass ratio of nano silicon dioxide, chitosan and magnesium stearate is 1:8:0.2.

Preparation examples 1 to 8

The difference from preparation example 1-1 is that the preparation method of the reinforced polypropylene fiber comprises the following steps:

(1) 1kg of polypropylene fiber is immersed into 10L of dilute hydrochloric acid solution with mass fraction of 5%, stirred for 10min at 60 ℃, and then washed to be neutral by deionized water for standby;

(2) Putting the polypropylene fiber treated in the step (1) into 5L of modified liquid, performing ultrasonic treatment at 80 ℃ for 25min, and then flushing with deionized water to be neutral for later use;

(3) And (3) drying the polypropylene fiber treated in the step (2) at the temperature of 120 ℃ for 10 hours to obtain the reinforced polypropylene fiber.

Preparation examples 1 to 9

(1) 1kg of polypropylene fiber is immersed into 10L of dilute hydrochloric acid solution with mass fraction of 5%, stirred for 15min at 70 ℃, and then washed to be neutral by deionized water for standby;

(2) Putting the polypropylene fiber treated in the step (1) into 5L of modified liquid, performing ultrasonic treatment at 90 ℃ for 35min, and then flushing with deionized water to be neutral for later use;

(3) And (3) drying the polypropylene fiber treated in the step (2) at the temperature of 150 ℃ for 5 hours to obtain the reinforced polypropylene fiber.

PREPARATION EXAMPLE 2-1

The preparation method of the modified ceramsite comprises the following steps:

(1) 1.5kg of ceramsite is soaked in 10L of 15% citric acid solution for 30min, washed to be neutral, and then calcined for 3h at 1000 ℃ for later use;

(2) Dispersing the ceramsite treated in the step (1) in a silane coupling agent solution, soaking for 2 hours, then adding nano titanium dioxide, stirring for 3 hours, and drying to obtain modified ceramsite, wherein the mass ratio of the ceramsite to the nano titanium dioxide to the silane coupling agent solution is 1:0.4:4.

PREPARATION EXAMPLE 2-2

The difference from preparation example 2-1 is that in step (2), the silane coupling agent solution is not added.

PREPARATION EXAMPLE 2-2

The difference from preparation example 2-1 is that nano titania is not added in step (2).

PREPARATION EXAMPLES 2 to 4

The difference from preparation example 2-1 is that the mass ratio of the ceramsite, the nano titanium dioxide and the silane coupling agent solution is 1:0.5:3.

PREPARATION EXAMPLES 2 to 5

The difference from preparation example 2-1 is that the mass ratio of the ceramsite, the nano titanium dioxide and the silane coupling agent solution is 1:0.2:5.

Preparation examples 2 to 6

The difference from preparation example 2-1 is that the mass ratio of the ceramsite, the nano titanium dioxide and the silane coupling agent solution is 1:0.8:1.5.

Preparation examples 2 to 7

The preparation method of the modified ceramsite comprises the following steps:

(1) 1.5kg of ceramsite is soaked in 10L of citric acid solution with the mass fraction of 12%, the soaking time is 20min, the ceramsite is washed to be neutral, and then the ceramsite is calcined for 3 hours at 900 ℃ for standby;

(2) Dispersing the ceramsite treated in the step (1) in a silane coupling agent solution, soaking for 1h, then adding nano titanium dioxide, stirring for 3h, and drying to obtain the modified ceramsite.

Preparation examples 2 to 8

The preparation method of the modified ceramsite comprises the following steps:

(1) 1.5kg of ceramsite is soaked in 10L of 15% citric acid solution for 35min, washed to be neutral, and then calcined for 2h at 1100 ℃ for standby;

(2) Dispersing the ceramsite treated in the step (1) in a silane coupling agent solution, soaking for 2 hours, then adding nano titanium dioxide, stirring for 2 hours, and drying to obtain the modified ceramsite.

Example 1 a special concrete with high water permeability comprising the following raw materials by weight: 700kg of coarse aggregate, 350 kg of fine aggregate, 250kg of cement, 180 kg of water kg, 50kg of fly ash, 30 kg of modified ceramsite, 8 kg of water reducer, 20kg of reinforced polypropylene fiber and 200kg of crushed stone. The crushed stone comprises 120kg of crushed stone with the grain size of 15-25mm and 80kg of crushed stone with the grain size of 20-30 mm.

The fly ash is pretreated by the following steps: grinding the fly ash, sieving the fly ash with a 500-mesh sieve, dispersing the fly ash in 100L oxalic acid solution with the concentration of 0.1mol/L for soaking for 25min, washing the fly ash with water to be neutral, calcining the fly ash at 400 ℃ for 20min, dispersing the fly ash in mixed solution for soaking for 35min, filtering and drying the mixed solution to obtain treated fly ash, wherein the mixed solution is prepared by dispersing 10kg of wood fiber powder in 80L of ethanol solution; the grade of the fly ash is two-grade, coarse aggregate adopts stone proportion with the grading of 5-10mm and 10-20mm, and fine aggregate adopts medium sand grain grading of 2-5 mm.

The special concrete with high water permeability is formed by stirring coarse aggregate, fine aggregate, cement, water, fly ash, modified ceramsite, a water reducing agent, reinforced polypropylene fiber and crushed stone.

Reinforced polypropylene fibers were prepared using preparation example 1-1; the modified ceramsite was prepared by using preparation example 2-1.

Comparative example 1

A special concrete with high water permeability is different from the concrete in example 1 in 550kg of coarse aggregate, 200kg of fine aggregate, 150kg of cement, 120kg of water, 20kg of fly ash, 10kg of modified ceramsite, 3 kg of water reducing agent, 8 kg of reinforced polypropylene fiber and 120kg of crushed stone. The broken stone comprises 10kg of broken stone with the grain size of 15-25mm and 110 parts of broken stone with the grain size of 20-30 mm.

Comparative example 2

The special concrete with high water permeability is different from the special concrete in example 1 in 800kg of coarse aggregate, 500 kg of fine aggregate, 350 kg of cement, 250kg of water, 70 kg of fly ash, 55 kg of modified ceramsite, 12 kg of water reducer, 35 kg of reinforced polypropylene fiber and 350 kg of crushed stone. The broken stone comprises 300kg of broken stone with the grain size of 15-25mm and 50 parts of broken stone with the grain size of 20-30 mm.

Comparative example 3

A special concrete with high water permeability is different from example 1 in that the modified ceramsite is replaced by an equal amount of ceramsite.

Comparative example 4

A special concrete with high water permeability is distinguished from example 1 in that the reinforcing polypropylene fibers are replaced by equal amounts of polypropylene fibers.

Comparative example 5

A special concrete with high water permeability is different from example 1 in that the reinforced polypropylene fiber is prepared by using preparation examples 1-2.

Comparative example 6

A special concrete with high water permeability is different from example 1 in that the reinforced polypropylene fiber is prepared by using preparation examples 1-3.

Comparative example 7

A special concrete with high water permeability is different from example 1 in that the reinforced polypropylene fiber is prepared by using preparation examples 1-4.

Example 2

A special concrete with high water permeability is different from example 1 in that the reinforced polypropylene fiber is prepared by using preparation examples 1 to 5.

Example 3

A special concrete with high water permeability is different from example 1 in that the reinforced polypropylene fiber is prepared by using preparation examples 1 to 6.

Comparative example 8

A special concrete with high water permeability is different from example 1 in that the reinforced polypropylene fiber is prepared by using preparation examples 1 to 7.

Comparative example 9

A special concrete with high water permeability is different from example 1 in that modified ceramsite is prepared by adopting preparation example 2-2.

Comparative example 10

A special concrete with high water permeability is different from example 1 in that modified ceramsite is prepared by adopting preparation examples 2-3.

Example 4

A special concrete with high water permeability is different from example 1 in that modified ceramsite is prepared by adopting preparation examples 2-4.

Example 5

A special concrete with high water permeability is different from example 1 in that modified ceramsite is prepared by adopting preparation examples 2-5.

Comparative example 11

A special concrete with high water permeability is different from example 1 in that modified ceramsite is prepared by adopting preparation examples 2-6.

Example 6

The special concrete with high water permeability is different from the special concrete in example 1 in 650kg of coarse aggregate, 300kg of fine aggregate, 200kg of cement, 150kg of water, 30 kg of fly ash, 15kg of modified ceramsite, 5kg of water reducer, 10kg of reinforced polypropylene fiber and 150kg of crushed stone. The broken stone comprises 100kg of broken stone with the grain size of 15-25mm and 50 parts of broken stone with the grain size of 20-30 mm.

Example 7

The special concrete with high water permeability is different from the concrete in the embodiment 1 in 750kg of coarse aggregate, 400 kg of fine aggregate, 300kg of cement, 200kg of water, 60 kg of fly ash, 45 kg of modified ceramsite, 10kg of water reducer, 30 kg of reinforced polypropylene fiber and 300kg of crushed stone. The broken stone comprises 200kg of broken stone with the grain size of 15-25mm and 100 parts of broken stone with the grain size of 20-30 mm.

Example 8

A special concrete with high water permeability is different from example 1 in that the reinforced polypropylene fiber is prepared by using preparation examples 1 to 8.

Example 9

A special concrete with high water permeability is different from example 1 in that the reinforced polypropylene fiber is prepared by using preparation examples 1 to 9.

Example 10

A special concrete with high water permeability is different from example 1 in that modified ceramsite is prepared by adopting preparation examples 2-7.

Example 11

A special concrete with high water permeability is different from example 1 in that modified ceramsite is prepared by adopting preparation examples 2-8.

Comparative example 12

The special concrete with high water permeability is different from the concrete in the embodiment 1 in that the fly ash is not soaked by the mixed solution in the fly ash pretreatment.

Performance test

The special concrete with high water permeability prepared in the examples and the comparative examples is subjected to mechanical property test, the concrete prepared in the examples and the comparative examples is respectively poured into a cubic standard sample with the dimensions of 100mm multiplied by 100mm, after curing for 28d, whether cracks are generated on the surface of the concrete sample is observed, the crack width is recorded, if the crack width is smaller than 0.5mm, the concrete is considered to be in a range allowing the cracks to appear, and if the crack width is larger than 0.5mm, the crack resistance of the concrete is considered to be weaker; meanwhile, the compressive strength and the splitting tensile strength of the sample after curing for 28 days are tested according to the detection standard of GB/T50081-2019 'test method Standard for physical and mechanical properties of concrete', and the test results are shown in Table 1 according to the specification CJJ/T135-2009 'test procedure for Water-permeable concrete pavement'.

Table 1 test data for examples and comparative examples

	Coefficient of water permeability, mm/s	Porosity%	Compressive strength, MPa	Split tensile strength, MPa	With or without cracks	Crack width, mm
							Example 1	3.5	15.8	69.8	6.5	Without any means for	/
Comparative example 1	2.9	13.8	65.4	5.7	Has the following components	0.4
							Comparative example 2	2.8	13.7	65.8	5.6	Has the following components	0.5
Comparative example 3	2.1	11.4	55.1	4.1	Has the following components	1.6
							Comparative example 4	2.3	12.1	52.2	3.5	Has the following components	2.1
Comparative example 5	3.7	16.2	60.2	4.9	Has the following components	0.9
							Comparative example 6	3.4	15.7	65.7	5.8	Has the following components	0.4
Comparative example 7	3.5	15.6	67.3	6.1	Without any means for	/
							Example 2	3.5	15.9	69.7	6.4	Without any means for	/
Example 3	3.4	15.6	69.6	6.5	Without any means for	/
							Comparative example 8	3.2	15.4	67.9	6.2	Without any means for	/
Comparative example 9	2.6	13.2	66.9	5.9	Has the following components	0.3
							Comparative example 10	2.9	13.9	62.5	5.2	Has the following components	0.8
Example 4	3.5	15.9	69.7	6.4	Without any means for	/
							Example 5	3.6	15.8	69.8	6.5	Without any means for	/
Comparative example 11	3.1	14.2	67.1	6.1	Without any means for	/
							Example 6	3.4	15.7	69.7	6.3	Without any means for	/
Example 7	3.5	15.8	69.5	6.4	Without any means for	/
							Example 8	3.4	15.6	69.6	6.3	Without any means for	/
Example 9	3.3	15.7	69.8	6.4	Without any means for	/
							Example 10	3.4	15.5	69.7	6.5	Without any means for	/
Example 11	3.5	15.8	69.6	6.4	Without any means for	/
							Comparative example 12	2.4	12.3	61.2	4.8	Has the following components	1.1

As can be seen from Table 1, the special concrete with high water permeability prepared in the examples 1, 2-3, 4-5 and 6-11 has better water permeability and mechanical property, the compressive strength reaches 69.8MPa, the splitting tensile strength reaches 6.5MPa, and no crack is generated, so that the special concrete prepared in the application has better mechanical property and cracking resistance while ensuring higher water permeability.

As shown in table 1, the water permeability of the concrete is less changed than that of the concrete in example 1, but the compressive strength is 60.2MPa, the splitting tensile strength is 4.9MPa, the crack is formed, and the crack width is 0.9mm, which indicates that the polypropylene fiber is soaked by the modifying liquid, so that the strength, the cracking resistance and the impact resistance of the fiber are improved, and the mechanical properties such as the strength, the cracking resistance and the impact resistance of the concrete are improved when the polypropylene fiber is subsequently applied to the concrete.

In the preparation method of the reinforced polypropylene fiber in the comparative example 6, chitosan is not added into the modified liquid, the water permeability of the concrete is not changed greatly, but the compressive strength is 65.7MPa, the splitting tensile strength is 5.8MPa, and the crack is formed, and the crack width is 0.4mm; in the preparation method of the reinforced polypropylene fiber in the comparative example 7, magnesium stearate is not added into the modified liquid, the water permeability of the concrete is not changed greatly, but the compressive strength is 67.3MPa, the splitting tensile strength is 6.1MPa, and no crack exists; in the preparation method of the reinforced polypropylene fiber in comparative example 8, the mass ratio of nano silicon dioxide, chitosan and magnesium stearate is changed, the water permeability of concrete is not greatly changed, the compressive strength and the splitting tensile strength are larger than those of comparative examples 6-7, but smaller than those of examples 2-3, the fact that the mechanical property of the reinforced polypropylene fiber is obviously influenced by not adding chitosan or magnesium stearate is shown, the mass ratio of nano silicon dioxide, chitosan and magnesium stearate is changed, the mechanical property of the reinforced polypropylene fiber is also influenced, the fact that the nano silicon dioxide, chitosan and magnesium stearate have a synergistic effect is shown, the nano silicon dioxide is loaded on the surface of the fiber by chitosan, and the nano silicon dioxide is uniformly attached on the surface of the fiber by magnesium stearate, so that the comprehensive property of the fiber is improved.

The modified ceramsite of comparative example 9 is not added with silane coupling agent solution, the water permeability coefficient of concrete is 2.6mm/s, the porosity is 13.2%, the compressive strength is 66.9MPa, the splitting tensile strength is 5.9MPa, and the crack is 0.3mm in width; the modified ceramsite of comparative example 10 is not added with nano titanium dioxide, the water permeability coefficient of concrete is 2.9mm/s, the porosity is 13.9%, the compressive strength is 62.5MPa, the splitting tensile strength is 5.2MPa, and the crack is 0.8mm in width; comparative example 11 changes the mass ratio of the ceramsite, the nano titanium dioxide and the silane coupling agent solution, the water permeability coefficient, the porosity, the compressive strength and the splitting tensile strength of the concrete are larger than those of comparative examples 9-10, but smaller than those of examples 4-5, and the fact that the water permeability and the mechanical properties of the modified ceramsite are obviously affected by the absence of the silane coupling agent solution or the nano titanium dioxide is shown, and the ceramsite, the nano titanium dioxide and the silane coupling agent solution have a synergistic effect, the nano titanium dioxide increases the mechanical properties of the ceramsite, the silane coupling agent enables the nano titanium dioxide to be uniformly dispersed, and meanwhile, the silane coupling agent increases the binding force of the ceramsite and the nano titanium dioxide, so that the strength of the ceramsite is improved.

As shown in Table 1, compared with example 1, the water permeability coefficient of the concrete is 2.4mm/s, the porosity is 12.3%, the compressive strength is 61.2MPa, the splitting tensile strength is 4.8MPa, cracks are formed, the crack width is 1.1mm, and the coal ash treated by the mixed solution can be dispersed in the pores of the coal ash, so that the structural strength of the coal ash is improved, the subsequent coal ash is applied to special concrete, and the binding force, mechanical property and cracking resistance of each component of the concrete are improved.

Comparative examples 1-2 the contents of the components in the special concrete were changed, and it is shown from Table 1 that the concrete has a water permeability coefficient of about 2.8mm/s, a porosity of about 13.7%, a compressive strength of about 65MPa, a split tensile strength of about 5.6MPa, cracks, and a crack width of about 0.5mm, compared with example 1, and that the concrete prepared with the contents of the components in a certain range has better water permeability and mechanical properties, and when the contents of the components exceed a certain range, the comprehensive properties of the concrete are significantly affected.

Comparative example 3 uses equivalent ceramsite instead of modified ceramsite, and as can be seen from table 1, compared with example 1, the water permeability coefficient of concrete is 2.1mm/s, the porosity is 11.4%, the compressive strength is 55.1MPa, the splitting tensile strength is 4.1MPa, cracks are formed, and the crack width is 1.6mm, so that the modified ceramsite prepared by the method has better water permeability and mechanical property, and is subsequently applied to concrete to improve the cracking resistance and impact resistance of the concrete.

Comparative example 4 uses equal amount of polypropylene fiber instead of reinforced polypropylene fiber, and as can be seen from table 1, compared with example 1, the water permeability coefficient of the concrete is 2.3mm/s, the porosity is 12.1%, the compressive strength is 52.2MPa, the split tensile strength is 3.5MPa, the crack is formed, the crack width is 2.1mm, and the reinforced polypropylene fiber prepared by the method has higher strength, is subsequently applied to the concrete, not only improves the water permeability of the concrete, but also enhances the crack resistance and the structural strength of the concrete.

The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.

Claims

1. The special concrete with high water permeability is characterized by comprising the following raw materials in parts by weight: 650-750 parts of coarse aggregate, 300-400 parts of fine aggregate, 200-300 parts of cement, 150-200 parts of water, 30-60 parts of fly ash, 15-45 parts of modified ceramsite, 5-10 parts of water reducer, 10-30 parts of reinforced polypropylene fiber and 150-300 parts of crushed stone.

2. The high water permeability special concrete according to claim 1, wherein the preparation method of the reinforced polypropylene fiber comprises the following steps:

the modified liquid comprises the following raw materials: nano silicon dioxide, N-dimethylacetamide, chitosan, magnesium stearate, a silane coupling agent and deionized water;

3. The special concrete with high water permeability according to claim 2, wherein the mass ratio of the nano silicon dioxide to the chitosan to the magnesium stearate is 1:2-6:0.5-0.8.

4. The special concrete with high water permeability according to claim 1, wherein the preparation method of the modified ceramsite comprises the following steps:

5. The special concrete with high water permeability according to claim 4, wherein the mass ratio of the ceramsite to the nano titanium dioxide to the silane coupling agent solution is 1:0.2-0.5:3-5.

6. The high permeability special concrete of claim 1, wherein the fly ash is pretreated by the steps of: grinding and sieving the fly ash, dispersing the fly ash in oxalic acid solution for 20-30min, washing with water to be neutral, calcining for 10-30min at 300-500 ℃, dispersing the fly ash in mixed solution for 30-40min, filtering and drying to obtain treated fly ash, wherein the mixed solution is prepared by dispersing wood fiber powder in ethanol solution.

7. The high water permeability special concrete according to claim 1, wherein the crushed stone comprises 100-200 parts of crushed stone with a grain size of 15-25mm and 50-100 parts of crushed stone with a grain size of 20-30 mm.

8. The high permeability special concrete of claim 1, wherein the water reducing agent is a polycarboxylate water reducing agent.