CN113372061B

CN113372061B - Preparation method of baking-free ecological fish nest brick

Info

Publication number: CN113372061B
Application number: CN202110689885.0A
Authority: CN
Inventors: 黄晓丽; 霍堂斌; 金星; 赵晨; 王慧博
Original assignee: Heilongjiang River Fisheries Research Institute of Chinese Academy of Fishery Sciences
Current assignee: Heilongjiang River Fisheries Research Institute of Chinese Academy of Fishery Sciences
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2021-12-14
Anticipated expiration: 2041-06-22
Also published as: CN113372061A

Abstract

A preparation method of baking-free ecological fish nest brick, which relates to a preparation method of baking-free ecological fish nest brick. The invention aims to solve the technical problem of waste caused by the fact that straw and fly ash are not utilized. The method comprises the following steps: firstly, preparing a straw fiber raw material; and secondly, putting the cement, the coarse sand and the fly ash into a stirrer, mixing and stirring for 5min, adding the straw fiber dispersion, putting into a mold, compacting on a compaction table, maintaining, demolding, and maintaining in a maintenance room with the temperature of 20 +/-1 ℃ and the relative humidity of not less than 90% for 28 days after demolding to obtain the straw fiber composite material. According to the method, the agricultural waste straw and the industrial waste fly ash are utilized, resource utilization is realized, the prepared burning-free ecological fish nest brick has a good adsorption effect on heavy metals, nitrogen and phosphorus in water, and the hollowed-out space can be used for sheltering larvae and fish or planting aquatic plants, so that the environment is restored and the water quality is purified. The invention belongs to the field of preparation of baking-free ecological fish nest bricks.

Description

Preparation method of baking-free ecological fish nest brick

Technical Field

The invention relates to a preparation method of a baking-free ecological fish nest brick.

Background

In recent years, in order to maintain the water and air permeability and biological diversity of natural river water and land interlaced belts, ecological slope protection is often adopted to ensure the habitat of fishes and aquatic organisms and realize the ecological function of a riparian zone. However, with the development of social economy and the improvement of environmental protection requirements, the requirements for ecological slope protection are increasingly improved, and besides flood control and water and soil conservation, the requirements for improving water environment capacity, ecological environment restoration and the like are increased. The fish nest brick is developed on the basis, and can provide safe reproduction and rest space for aquatic organisms such as fish and the like and amphibians. The fish nest brick can meet the stability of a riverway side slope and the functions of flood control and drainage of the riverway, is used as a sheltering place for aquatic organisms such as fishes, helps the fishes to avoid natural enemies, reduces the damage to the fishes caused by rapid water flow, sand stones and the like in flood seasons, and can provide space for the growth of aquatic plants. The fish nest brick has preliminary research in China, but most of the fish nest brick focuses on the structural design, and the development and research on the preparation process and diversified functions of the fish nest brick are less. The invention and application of the multifunctional fish nest brick are the trend of river course revetment development. Straw is a main byproduct in agricultural production, and has huge yield and wide source. The fly ash is fine ash collected from flue gas generated after coal combustion, and is also main solid waste discharged from a coal-fired power plant. The straw and the fly ash cause waste if not used.

Disclosure of Invention

The invention aims to solve the technical problem that straw and fly ash are not used to cause waste, and provides a preparation method of a baking-free ecological fish nest brick.

The preparation method of the baking-free ecological fish nest brick is carried out according to the following steps:

firstly, preparing straw fiber raw materials:

cutting straw stalk into pieces with length of 20-40mm, air separating, removing light impurities, sieving with 18 mesh sieve to remove heavy impurities and grains, steaming in NaOH alkaline solution at 100 deg.C for 120min, cleaning, and sun drying to obtain straw fiber;

wherein NaOH alkali liquor accounts for 8% of the mass of the absolutely dry straw raw material;

secondly, weighing the cement, the coarse sand, the fly ash, the straw fiber and the water according to the mass ratio of 1: 1.8: 1.2: 0.03: 0.8 of the cement, the coarse sand, the fly ash, the straw fiber and the water;

dispersing the straw fiber in water to obtain a straw fiber dispersion liquid, putting cement, coarse sand and fly ash into a stirrer to be mixed and stirred for 5min, adding the straw fiber dispersion liquid, and fully stirring to obtain mixed mortar;

and putting the mixed mortar into a mold, compacting on a compaction table, curing the test mold in a curing box for 24 hours, demolding, and continuously curing in a curing room with the temperature of 20 +/-1 ℃ and the relative humidity of not less than 90% for 28 days after demolding to obtain the baking-free ecological fish nest brick.

And step two, the fly ash is class II and is used after being dried.

And step two, the coarse sand is naturally dried and then is sieved by a 40-mesh sieve for use.

And step two, the cement is Portland cement with the minimum compressive strength of 42.5MPa in 28 days.

In the process of preparing the baking-free ecological fish nest brick, bricks with different shapes can be prepared by adopting different moulds according to requirements, such as: cubic, perforated brick, hollow hexagon, block.

The straw stalks are directly mixed into the concrete, which can not play a role in enhancing the strength and toughness of the brick body, but can reduce the strength of the brick body; if the ecological brick is added with the straw powder, the function of increasing the toughness and the strength can not be achieved. Therefore, the straw fiber needs to be separated, is in a bundle shape and is easy to disperse in water, and can be fully mixed with concrete to enhance the toughness and strength of the brick body.

The lignin of the rice straw is removed, and then the fiber is separated by two methods: alkali treatment and acid treatment. Under the acidic condition, cellulose and hemicellulose in the straws are easy to hydrolyze, so that the straws are greatly damaged, and the subsequent utilization is influenced. The alkali treatment method has low cost and simple and convenient treatment method, so the invention adopts the alkali treatment method.

The purpose of the NaOH alkali liquor treatment is to remove lignin from the straw stalks and further separate fibers. Parameters such as cooking temperature, heat preservation time, NaOH dosage and the like play a vital role in removing lignin and separating fiber. Lignin, pectin and some macromolecular substances in the straw fiber can be degraded only at a higher temperature, so that the effect cannot be achieved at a too low temperature. When the temperature is greater than 100 ℃, the rate of lignin removal is less than the rate of temperature increase, while the temperature increase will result in the degradation of carbohydrates including cellulose and hemicellulose. In addition, the cooking temperature is one of the important factors of energy consumption in the process, and 100 ℃ at normal pressure is adopted as the final temperature from the viewpoints of resources, cost and material performance. Thus not only ensuring the separation of the fiber, but also ensuring the yield of the straw fiber.

The lignin removal is closely related to the heat preservation time, the complete lignin removal cannot be guaranteed in a short time, and the hydrolysis of carbohydrates can be caused in a long time. With the increase of the heat preservation time, the yield of the straw stalk fiber is gradually reduced. And (3) at the stage of removing a large amount of lignin in 30-90 min, combining NaOH with hydroxyl and ether bonds in the lignin to generate sodium salt, so that the macromolecular structure of the lignin is degraded and dissolved in alkali liquor. The time period of 90-120 min is the degradation stage of carbohydrate. In order to ensure the performance of the straw fiber, the heat preservation time is preferably prolonged, so that 120min is selected as the heat preservation time.

NaOH can react with lignin and hemicellulose in the slurry to generate sodium salt, but the lignin removal effect is poor due to too low consumption of NaOH, the prepared fibers have poor dispersion performance, and environmental pollution is caused by too high consumption of NaOH. As the amount of NaOH is increased, the yield of the straw fiber is gradually reduced and shows a linear relationship. The NaOH dosage has great influence on the removal of lignin, and the rate of decline of the brown stock yield tends to be smooth in the process that the NaOH dosage is from 8 percent to 10 percent, so the NaOH dosage is selected to be 8 percent.

The invention is maintained after demoulding to ensure that the cement mortar reaches the design strength within the specified age and prevent shrinkage cracks. If the curing is not timely, the cement can not be fully hydrated, and the phenomenon that the strength of the powder concrete on the surface of the concrete is unqualified can occur. Factors that affect the quality of the cement mortar maintenance include temperature, humidity and age. At temperatures below 0 c, the water content of the mortar has already begun to partially freeze, which leads to freezing damage to the mortar, and therefore the curing temperature of the mortar is guaranteed. However, the higher the temperature is, the more beneficial the strength of the cement mortar is, and when the temperature is too high, the moisture on the surface of the cement mortar can be greatly evaporated, so that the hydration of the surface layer of the cement mortar is poor due to water shortage, the hydration speed of the internal cement is obviously accelerated, and the distribution of hydration products is not uniform, thereby further influencing the hydration of the cement and the development of later strength. The curing temperature is 5 ℃ every time, and the strength is reduced by 1.0MPa after 28 days. The temperature of room temperature is 20 +/-1 ℃, so that the cement hydration reaction is ensured to be smoothly carried out, and the later strength development is not influenced by too high temperature.

The humidity of cement mortar curing is very important, and drying dehydration can affect the hydration of cement, and can also cause the cement mortar to bear the tensile stress caused by shrinkage under a low-strength state, so that cracks appear on the surface of concrete, and the strength is finally affected, therefore, the concrete is required to be kept at a sufficient humidity in the curing period. At a relative humidity of less than 80%, cement hydration tends to stop and if the cement mortar is dried early, its strength, impermeability and durability are adversely affected.

The 28-day strength is the basis for determining the compressive strength of the cement cube. The strength increasing process of the concrete is the process of hydration reaction of chemical components (silicate, aluminate and the like) in the cement. Under standard 28-day conditions, the strength is about 97% of its 90-day strength and about 99% of its 180-day strength. After 180 days, although the strength still increases, the increase is small and extremely slow. The strength of the concrete still increases after 6 years, but the increase rate is only about 1%.

After the cement is finally set, the humidity of the concrete is kept to be more than 95%, the temperature is 20 ℃, and the optimum curing condition is 1 standard atmospheric pressure.

Straw is a main byproduct in agricultural production, and has huge yield and wide source. The concrete prepared from the plant fiber can meet the requirements of low carbon, environmental protection, convenient material acquisition, light weight and high strength. The concrete is doped with a certain amount of fly ash, so that the drying shrinkage of the concrete can be effectively reduced, the crack resistance and the temperature crack prevention capability of the concrete can be improved, and the durability of the concrete can be improved. Therefore, the straw and the fly ash are applied to the preparation of the fish nest brick, so that the resource utilization of wastes can be realized, and the aim of protecting the ecological environment can be fulfilled.

In view of the above, the preparation method of the baking-free ecological fish nest brick with the water purification function provided by the invention better overcomes the problems in the prior art, and realizes resource utilization of straw and fly ash to a certain extent. The rice straw is treated to obtain straw fiber, and then the fish nest brick prepared by mixing raw materials such as cement, fly ash, straw fiber, coarse sand and the like is used for treating ammonia nitrogen, TP and Cu in water²⁺、Cd²⁺Has good adsorption and purification performance.

The invention has the advantages that:

(1) the method utilizes the agricultural waste straw and the industrial waste fly ash, thereby realizing resource utilization;

(2) the baking-free ecological fish nest brick prepared by the method has good adsorption effect on heavy metals, nitrogen and phosphorus in water; (3) the baking-free ecological fish nest brick prepared by the method has the advantages that the hollow space can be used for sheltering larvae and fish or planting aquatic plants, so that the environment is restored and the water quality is purified.

Drawings

FIG. 1 is a schematic structural view of a baking-free ecological fish nest brick in experiments I to III;

FIG. 2 is a schematic front structure view of the baking-free ecological fish nest brick in experiments one to three;

fig. 3 is a schematic side structure view of the baking-free ecological fish nest brick in experiments one to three.

Detailed Description

The technical solution of the present invention is not limited to the following specific embodiments, but includes any combination of the specific embodiments.

The first embodiment is as follows: the preparation method of the baking-free ecological fish nest brick of the embodiment is carried out according to the following steps:

firstly, preparing straw fiber raw materials:

The second embodiment is as follows: the difference between the first embodiment and the second embodiment is that the fly ash in the second step is class II and is used after being dried. The rest is the same as the first embodiment.

The third concrete implementation mode: the difference between the first embodiment and the second embodiment is that the coarse sand in the second step is naturally dried and then is sieved by a 40-mesh sieve for use. The others are the same as in the first or second embodiment.

The fourth concrete implementation mode: the difference between the present embodiment and one of the first to third embodiments is that the cement in the second step is portland cement having a minimum compressive strength of 42.5MPa in 28 days. The rest is the same as one of the first to third embodiments.

The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is that the second step is released from the mold and then is maintained in a curing chamber with a temperature of 19 ℃ and a relative humidity of not less than 90% for a period of 28 days. The rest is the same as one of the first to fourth embodiments.

The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is that the second step is released from the mold and then is maintained in a curing chamber with a temperature of 20 ℃ and a relative humidity of not less than 90% for a period of 28 days. The rest is the same as one of the first to fifth embodiments.

The seventh embodiment: the difference between this embodiment and the first to sixth embodiments is that the second step is demolded and then is maintained in a curing chamber with a temperature of 21 ℃ and a relative humidity of not less than 90% for a period of 28 days. The rest is the same as one of the first to sixth embodiments.

The specific implementation mode is eight: the difference between this embodiment mode and one of the first to seventh embodiment modes is that the first step is to cut the straw stalk material into grass pieces with the length of 20 mm. The rest is the same as one of the first to seventh embodiments.

The specific implementation method nine: the difference between the first embodiment and the first to eighth embodiments is that the first step is to cut the straw stalk into grass pieces with the length of 30 mm. The rest is the same as the first to eighth embodiments.

The detailed implementation mode is ten: the difference between this embodiment mode and one of the first to ninth embodiment modes is that the first step is to cut the straw stalk material into grass pieces with the length of 40 mm. The rest is the same as one of the first to ninth embodiments.

The following experiments are adopted to verify the effect of the invention:

experiment one:

the preparation method of the baking-free ecological fish nest brick with the combination of the figures 1 to 3 is carried out according to the following steps:

firstly, preparing straw fiber raw materials:

cutting straw stalk into pieces with length of 20mm, air separating, grading, removing light impurities, sieving with 18 mesh sieve to remove heavy impurities and grains, decocting qualified pieces in NaOH alkali solution at 100 deg.C for 120min, cleaning, and sun drying to obtain straw fiber;

and putting the mixed mortar into a mold, compacting on a compaction table, curing the test mold in a curing box for 24 hours, demolding, and continuously curing in a curing room with the temperature of 19 ℃ and the relative humidity of not less than 90% for 28 days after demolding to obtain the baking-free ecological fish nest brick.

And step two, the fly ash is class II and is used after being dried.

According to the growth and propagation of fish and the fattening characteristics of the fish with the bait, the single body appearance and the relevant size of the baking-free ecological fish nest brick in the experiment are shown in figure 1. The size of the main body part of the brick body is 350 multiplied by 200 multiplied by 150mm, front holes 3 are respectively arranged above and below the baking-free ecological fish nest brick, side holes 4 are respectively arranged in the front and the back of the baking-free ecological fish nest brick, grooves 1 are arranged on one side of the front and the back of the baking-free ecological fish nest brick, bumps 2 are arranged on the other side of the baking-free ecological fish nest brick, the left side and the right side of the baking-free ecological fish nest brick are hollowed, the baking-free ecological fish nest brick is hollowed inside and communicated up and down, two adjacent baking-free ecological fish nest bricks are inserted into the grooves 1 through the bumps 2, a space with the size of 100 multiplied by 50mm can be formed after the baking-free ecological fish nest bricks are connected and combined, and living and sheltering spaces are provided for fish and other aquatic organisms.

And (3) carrying out constant-temperature oscillation adsorption test on the unfired ecological fish nest brick prepared in the first experiment under the conditions of the temperature of 25 ℃, the rotating speed of 120r/min, the initial ammonia nitrogen concentration of 1.0mg/L, the phosphorus concentration of 0.5mg/L, the initial copper ion concentration of 30mg/L and the cadmium ion concentration of 0.5mg/L, and after 4 hours of constant-temperature oscillation, removing rate of ammonia nitrogen, phosphorus, cadmium and copper ions of the unfired ecological fish nest brick material is 61%, 56%, 18% and 12%. The vertical compression strength was determined to be 131 KN.

Experiment two:

firstly, preparing straw fiber raw materials:

cutting straw stalk into 30mm long pieces, air separating, removing light impurities, sieving with 18 mesh sieve to remove heavy impurities and grains, decocting the qualified pieces in NaOH solution at 100 deg.C for 120min, cleaning, and sun drying to obtain straw fiber;

and putting the mixed mortar into a mold, compacting on a compaction table, curing the test mold in a curing box for 24 hours, demolding, and continuously curing in a curing room with the temperature of 20 ℃ and the relative humidity of not less than 90% for 28 days after demolding to obtain the baking-free ecological fish nest brick.

And step two, the fly ash is class II and is used after being dried.

And (3) carrying out constant-temperature oscillation adsorption test on the baking-free ecological fish nest brick prepared in the second experiment under the conditions of the temperature of 25 ℃, the rotating speed of 120r/min, the initial ammonia nitrogen concentration of 1.0mg/L, the phosphorus concentration of 0.5mg/L, the initial copper ion concentration of 30mg/L and the cadmium ion concentration of 0.5mg/L, and after 4 hours of constant-temperature oscillation, removing rate of ammonia nitrogen, phosphorus, cadmium and copper ions of the baking-free ecological fish nest brick material is 70%, 65%, 20% and 20% respectively. The vertical compression strength was determined to be 132 KN.

Experiment three:

firstly, preparing straw fiber raw materials:

cutting straw stalk into 40mm long pieces, air separating, removing light impurities, sieving with 18 mesh sieve to remove heavy impurities and grains, decocting the qualified pieces in NaOH solution at 100 deg.C for 120min, cleaning, and sun drying to obtain straw fiber;

and putting the mixed mortar into a mold, compacting on a compaction table, curing the test mold in a curing box for 24 hours, demolding, and continuously curing in a curing room with the temperature of 21 ℃ and the relative humidity of not less than 90% for 28 days after demolding to obtain the baking-free ecological fish nest brick.

And step two, the fly ash is class II and is used after being dried.

And (3) carrying out constant-temperature oscillation adsorption test on the unfired ecological fish nest brick prepared in the third experiment under the conditions of the temperature of 25 ℃, the rotating speed of 120r/min, the initial ammonia nitrogen concentration of 1.0mg/L, the phosphorus concentration of 0.5mg/L, the initial copper ion concentration of 30mg/L and the cadmium ion concentration of 0.5mg/L, wherein after 4 hours of constant-temperature oscillation, the unfired ecological fish nest brick material has the ammonia nitrogen removal rate of 78%, the phosphorus removal rate of 73%, the cadmium ion removal rate of 31% and the copper ion removal rate of 25%. The vertical compression strength was determined to be 134 KN.

And (3) carrying out constant-temperature oscillation adsorption tests on the unfired ecological fish nest bricks prepared in the first experiment to the third experiment at the temperature of 25 ℃, the rotating speed of 120r/min, the initial ammonia nitrogen concentration of 1.0mg/L, the phosphorus concentration of 0.5mg/L, the initial copper ion concentration of 30mg/L and the cadmium ion concentration of 0.5mg/L, wherein after 4 hours of constant-temperature oscillation, the unfired ecological fish nest brick material has the ammonia nitrogen removal rate of 61-78%, the phosphorus removal rate of 56-73%, the cadmium ion removal rate of 18-31% and the copper ion removal rate of 12-25%. The vertical compression strength was determined to be 132. + -. 1.73 KN.

Experiment four: after the ecological brick is continuously maintained in a maintenance room with the temperature of 20 +/-1 ℃ and the relative humidity of not less than 90% for 3 days and 7 days, the vertical compressive strength of the ecological brick is respectively 38KN and 67KN which are far lower than that of the ecological brick prepared by the first experiment to the third experiment and maintained for 28 days.

Claims

1. The preparation method of the baking-free ecological fish nest brick is characterized by comprising the following steps:

firstly, preparing straw fiber raw materials:

2. The method for preparing the baking-free ecological fish nest brick according to claim 1, wherein the fly ash is grade II and is used after being dried.

3. The preparation method of the baking-free ecological fish nest brick according to claim 1, characterized in that the coarse sand is used after being screened by a 40-mesh sieve after being naturally dried in the sun.

4. The method for preparing the baking-free ecological fish nest brick according to the claim 1, characterized in that the cement is portland cement with 28 days compressive strength of 42.5MPa at the lowest.

5. The method for preparing the baking-free ecological fish nest brick according to the claim 1, characterized in that the baking-free ecological fish nest brick is still placed in a curing room with the temperature of 19 ℃ and the relative humidity of not less than 90 percent for continuous curing for 28 days after being demolded.

6. The method for preparing the baking-free ecological fish nest brick according to the claim 1, characterized in that the baking-free ecological fish nest brick is still placed in a curing room with the temperature of 20 ℃ and the relative humidity of not less than 90 percent for continuous curing for 28 days after being demolded.

7. The method for preparing the baking-free ecological fish nest brick according to the claim 1, characterized in that the baking-free ecological fish nest brick is still placed in a curing room with the temperature of 21 ℃ and the relative humidity of not less than 90 percent for continuous curing for 28 days after being demolded.