Cement-wood pervious concrete and preparation method thereof

Abstract

The invention discloses cement-wood pervious concrete and a preparation method thereof, and relates to the field of concrete, and the cement-wood pervious concrete is prepared from cement, wood-impregnated aggregate and water in a weight ratio of 100: (30-55): (40-65). Organic acid contained in the wood-impregnated aggregate reacts with calcium hydroxide in the concrete to generate acidic calcium which can permeate into soil and cannot generate a blocking phenomenon in the water-permeable concrete, the wood-impregnated aggregate is connected in the cement-wood water-permeable concrete in a root-to-root manner to form a filiform structure, the anti-cracking function and cohesiveness of the material are improved, and the wood-impregnated aggregate has the advantages of being high in cohesiveness, high in durability and the like. The use function of the cement pervious concrete is improved, and the service life of the cement pervious concrete is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and particularly relates to a cement wood permeable concrete and a preparation method thereof. Background Art

[0002] At present, there are many quality common problems in cement permeable concrete. Surface blockage, easy cracking and internal biofilms seriously affect the service function and lifespan of cement permeable concrete. First, the sand and soil in the surface gaps of cement permeable concrete are prone to form a hardpan phenomenon. The sand and soil in the surface gaps come from the dust in the air and the sand and soil brought by rain runoff. When a series of chemical reactions occur between calcium hydroxide in the permeable concrete and aluminum hydroxide in the sand and soil in the gaps, it causes the sand and soil in the surface gaps of the permeable concrete to form a hardpan "saline-alkali land". Second, the formation of internal biofilms in cement concrete is also likely to block its internal gaps. Third, the contact surface between the cement gel and the aggregate in cement permeable concrete is small, resulting in the cracking phenomenon of cement permeable concrete.

[0003] Therefore, those skilled in the art are committed to developing a crack-resistant and blockage-preventing permeable concrete. The cement wood permeable concrete provided by the present invention solves the "efflorescence" of permeable concrete and resists the formation of internal biofilms in permeable concrete, and slows down the blockage problem of permeable concrete. Adding coarse impregnated wood aggregate to permeable concrete solves the cracking problem of permeable concrete. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that the existing cement permeable concrete has surface blockage, easy cracking and internal biofilms, etc., which seriously affect the service function and lifespan of cement permeable concrete. The present invention provides a crack-resistant and blockage-preventing cement wood permeable concrete and a preparation method thereof to overcome the problems of poor bonding performance, easy cracking and blockage of existing concrete, and improve the service function and lifespan of cement permeable concrete.

[0005] To achieve the above object, the present invention provides a cement wood permeable concrete, wherein the weight ratio of cement, impregnated wood aggregate, and water is cement: impregnated wood aggregate: water = 100: (30 - 55): (40 - 65).

[0006] The specifications of the impregnated wood aggregate are as follows: length 20 - 40 mm, average diameter 10 - 15 mm.

[0007] Cement: Ordinary Portland Cement.

[0008] Preferably, the impregnated wood aggregate of the present invention is prepared by the following method: soaking the wooden aggregate in an anti-corrosion and water-repellent agent, fishing it out and drying to obtain the impregnated wood aggregate;

[0009] Preferably, the above anti-corrosion and water-repellent agent includes wood vinegar liquid, and may also include chitosan and / or sodium alginate.

[0010] Preferably, the weight ratio of wood vinegar liquid, chitosan and sodium alginate in the anti-corrosion and water-repellent agent is (10 - 100):(1 - 5):(0.5 - 1).

[0011] Preferably, the anti-corrosion and water-repellent agent is diluted with water at 2% - 5% and then the woody aggregate is soaked.

[0012] Preferably, the soaking time of the woody aggregate in the anti-corrosion and water-repellent agent is 1 - 15 days.

[0013] The present invention also provides a preparation method of cement wood permeable concrete, which comprises the following steps:

[0014] Step 1: Preparation of soaked wood aggregate

[0015] The woody aggregate is soaked in the anti-corrosion and water-repellent agent for 1 - 15 days, fished out and dried to obtain the soaked wood aggregate, wherein the ratio of the anti-corrosion and water-repellent agent is that the weight ratio of wood vinegar liquid, chitosan and sodium alginate is (10 - 100):(1 - 5):(0.5 - 1), and the anti-corrosion and water-repellent agent is diluted with water at 2% - 5% and then the woody aggregate is soaked.

[0016] Step 2: Preparation of cement wood permeable concrete

[0017] The soaked wood aggregate is wetted with water and then added into a concrete mixer, and cement is added and stirred so that the wetted soaked wood aggregate and cement form a cemented state, and then water is added and stirred to obtain cement wood permeable concrete.

[0018] Preferably, the stirring time in Step 2 is 60 - 180 seconds.

[0019] Technical effects

[0020] 1. The concrete of the present invention has strong bonding performance.

[0021] The woody aggregate is treated with the anti-corrosion and water-repellent agent to obtain the soaked wood aggregate, and a dense modified lignin film is formed on the surface of the soaked wood aggregate. When the soaked wood aggregate is stirred with cement and water, the ions in the solution impact and collide with the surface of the soaked wood aggregate, causing a part of the modified lignin on the surface of the soaked wood aggregate to migrate and diffuse into the cement paste, and on the outer ionization layer of the cement particles, it combines with the hydrated ions of the cement particles to form a new molecular film.

[0022] 2. The concrete of the present invention is crack-resistant.

[0023] The soaked wood aggregates are connected to each other in the cement wood permeable concrete, forming a fibrillar structure, which improves the crack resistance of the material.

[0024] 3. The concrete of the present invention is anti-blocking.

[0025] Since calcium hydroxide in the cement wood concrete reacts with the organic acid material to produce acidic calcium, which is loose and penetrates into the soil under the scouring of rainwater, it will not react with carbon monoxide and dust in the air and will not cause blockage inside the permeable concrete. Brief Description of the Drawings

[0026] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the drawings to fully understand the purpose, features and effects of the present invention.

[0027] Figure 1 is an application example of the cement wood permeable concrete base in Embodiment 1 of the present invention; Detailed Embodiments

[0028] The following introduces multiple preferred embodiments of the present invention with reference to the drawings of the specification to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0029] The present invention provides a cement wood permeable concrete, wherein the weight ratio of cement, impregnated wood aggregate, and water is cement: impregnated wood aggregate: water = 100: (30 - 55): (40 - 65).

[0030] The specifications of the impregnated wood aggregate are: length 20 - 40 mm, average diameter 10 - 15 mm.

[0031] Cement: Ordinary Portland Cement

[0032] Preferably, the impregnated wood aggregate of the present invention is prepared by the following method: soaking the wooden aggregate in an antiseptic and water-repellent agent, fishing out and drying to obtain the impregnated wood aggregate;

[0033] Preferably, the above antiseptic and water-repellent agent includes wood vinegar liquid, and may also include chitosan and / or sodium alginate.

[0034] Preferably, the weight ratio of wood vinegar liquid, chitosan and sodium alginate in the antiseptic and water-repellent agent is (10 - 100): (1 - 5): (0.5 - 1).

[0035] Preferably, the soaking time of the wooden aggregate is 1 - 15 days.

[0036] The preparation method of the cement wood permeable concrete is as follows:

[0037] Spray the impregnated wood aggregate with water and add it to the concrete mixer, stir (for about 30 seconds) to make the wetted impregnated wood aggregate form a cemented state with the cement, and then add water and stir (for about 3 minutes) to obtain the cement wood permeable concrete.

[0038] Example 1

[0039] Step 1: Preparation of impregnated wood aggregates

[0040] The wooden aggregates are soaked in the antiseptic and water-repellent agent for 2 days, fished out and dried to obtain impregnated wood aggregates, where:

[0041] - Ratio of antiseptic and water-repellent agent: Wood vinegar; Chitosan: Sodium alginate = 50:3:1, diluted with water at 2% before use;

[0042] - Ratio of woody aggregates to preservative: Woody aggregates: Preservative = 1:0.4;

[0043] - Soaking time: After 48 hours, dry to a moisture content < 15%.

[0044] Step 2: Preparation of concrete

[0045] The impregnated wood aggregates are wetted with water and then added to a concrete mixer. Cement is added and stirred (for about 30 seconds) to form a cementitious state between the wetted impregnated wood aggregates and the cement. Then water is added and stirred (for about 3 minutes) to obtain cementitious woody permeable concrete.

[0046] - Raw material ratio: Cement: Impregnated wood aggregates: Water = 100:38:50

[0047] - Specific operation:

[0048] - 38 kg of impregnated wood aggregates are wetted with water (pre-adding 5 kg of water);

[0049] - 100 kg of cement is added and stirred for 30 seconds;

[0050] - 45 kg of water is added and stirred for 3 minutes.

[0051] Example 2

[0052] Step 1: The ratio of the preservative remains unchanged. The difference from Example 1 is that the ratio of woody aggregates to the preservative is 1:0.3;

[0053] Step 2: The method is the same as that in Example 1. The difference is the raw material ratio: Cement: Aggregates: Water = 100;50:60

[0054] Example 3

[0055] Step 1: The ratio of the preservative remains unchanged. The difference from Example 1 is that the ratio of woody aggregates to the preservative is 100:50;

[0056] Step 2: The method is the same as that in Example 1. The difference is the raw material ratio: Cement: Impregnated wood aggregates: Water = 100:30:45.

[0057] Performance analysis

[0058] 1. The performance of the cement-wood permeable concrete prepared in Example 1 was tested, and the results are as follows:

[0059] - The compressive strength reached 22.5 MPa, meeting the C20 permeable concrete standard;

[0060] - The water permeability coefficient was 3.2 mm / s, taking into account both water permeability and structural strength;

[0061] - The water absorption rate was only 4.8%, and the preservative effectively sealed the wood pores.

[0062] 2. Performance comparison between Example 2 and Example 3 and Example 1:

[0063] - In Example 2, due to insufficient preservative, the water absorption rate increased and the corrosion resistance decreased; the water absorption rate of the untreated aggregate exceeded 12%, and water swelling caused structural damage; the imbalance in the preservative ratio resulted in caking, affecting the bonding strength.

[0064] - In Example 3, due to the increase in the cement ratio, the water permeability was sacrificed, making it more suitable for high-load scenarios.

[0065] - Additionally, if the amount of cement is too small, the bonding between aggregates is insufficient, resulting in a sharp drop in strength.

[0066] The core innovation of the present invention lies in:

[0067] 1. Synergistic effect of preservatives: Wood vinegar liquid penetration anti-corrosion + chitosan antibacterial + sodium alginate film-forming, triple protection;

[0068] 2. Optimal ratio control: When the aggregate:preservative = 1:0.4, complete coating is achieved, and when the cement:aggregate = 1:0.38, a continuous pore structure is formed;

[0069] As Figure 1 shown, the application example of the cement-wood permeable concrete base in Example 1 of the present invention. It can be seen from the figure that the wood aggregates and cement are evenly mixed, the wood aggregates crisscross, and the cement is wrapped around the wood materials.

[0070] Reasons for the surface blockage of cement permeable concrete: The cement gel in cement permeable concrete undergoes a hydration reaction with water to generate calcium silicate, calcium hydroxide, etc. Calcium hydroxide remains in the cement permeable concrete for a long time. When the cement permeable concrete is soaked in water, calcium hydroxide reacts with water to form a solution that precipitates from the gaps in the cement permeable concrete and accumulates on the surface of the cement permeable concrete. The calcium hydroxide solution undergoes a secondary chemical reaction with aluminum hydroxide in the sand to generate calcium aluminate. Calcium aluminate reacts with carbon dioxide in the air to form calcium bicarbonate. Calcium bicarbonate is easily decomposed by water to form calcium carbonate solids. Calcium carbonate is insoluble in water and is not easily decomposed at room temperature. This is because there is a large amount of aluminum hydroxide in the sand. Aluminum hydroxide is an amphoteric hydroxide that can react chemically with both acids and strong bases. On the other hand, calcium hydroxide is a strong base with a large adsorption capacity.

[0071] Functions of impregnated wood aggregates in cement wood permeable concrete: Since the contact surface between the cement gel and the aggregates in cement permeable concrete is small, cracks are likely to occur under the action of external and internal forces, leading to quality problems of cement permeable concrete. Adding impregnated wood aggregates to cement permeable concrete can play a role in cracking resistance of cement permeable concrete. Impregnated wood aggregates have the properties of flexural strength, impact resistance, fatigue resistance, freeze-thaw resistance, and good toughness. The impregnated wood aggregates are randomly distributed in the permeable concrete, which can effectively hinder the expansion of microcracks and the formation of macro-cracks in the concrete. In addition, impregnated wood aggregates are a multi-phase composite material. The irregular impregnated wood aggregates grow obliquely and horizontally inside the concrete, causing a water storage phenomenon inside the structure of the cement permeable concrete, and it is a treasure trove for the atmospheric circulation in the air.

[0072] Functions of cement gel in preventing the swelling of impregnated wood aggregates when exposed to water, dehydration shrinkage, and decay of wood fibers: The quality problems caused by the swelling of impregnated wood aggregates when exposed to water, dehydration shrinkage, and decay of wood fibers are due to the continuous erosion of the impregnated wood aggregates by water. The cement gel on the surface of the impregnated wood aggregates can prevent water molecules from invading the interior of the wood fibers. On the one hand, the main components of impregnated wood aggregates are cellulose, hemicellulose, and lignin, which are all organic compounds containing polar functional groups. Inside the wood fibers, due to the intermolecular forces, these polar groups attract each other to reach a balanced state.

[0073] Due to the polarity of the impregnated wood aggregate, it has a certain surface free energy, and when the cement sets, they can bond with each other. On the other hand, the impregnated wood aggregate belongs to the porous-capillary-colloid type, and its cell wall is composed of microcrystals, microfibers and fibers. There are gaps between these microcrystals and microcrystals, microfibers and microfibers, and fibers and fibers, which are interconnected to form the microcapillary system of the wood. Therefore, its surface is convenient for the adsorption and conduction of liquids. To sum up, the solid cement gel can block the capillary channels of the impregnated wood aggregate, and the cement gel bonded to the surface of the impregnated wood aggregate improves the density and strength of the material, making it difficult for air and water molecules to enter the impregnated wood aggregate, thus ensuring the service life of the impregnated wood aggregate in the permeable concrete.

[0074] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in this technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A cement-based woody permeable concrete, characterized in that, Among them, the weight ratio of cement, wood-soaked aggregate, and water is cement: wood-soaked aggregate: water = 100: (30 - 55): (40 - 65).

2. A cement-based woody permeable concrete according to claim 1, characterized in that, The specifications of the wood-soaked aggregate are a length of 20 - 40 mm and an average diameter of 10 - 15 mm.

3. A cement-based woody permeable concrete as claimed in claim 1, characterized in that, The cement is ordinary Portland cement.

4. A cement-based woody permeable concrete according to claim 2, characterized in that, The wood-soaked aggregate is prepared by the following method: soaking the wooden aggregate in an anti-corrosion and water-repellent agent, fishing it out and drying it to obtain the wood-soaked aggregate.

5. A cement wood permeable concrete according to claim 4, characterized in that, The anti-corrosion and water-repellent agent includes wood vinegar liquid, and also includes chitosan and / or sodium alginate.

6. A cement wood permeable concrete according to claim 5, characterized in that, In the anti-corrosion and water-repellent agent, the weight ratio of wood vinegar liquid, chitosan, and sodium alginate is (10 - 100): (1 - 5): (0.5 - 1).

7. A cement-wood permeable concrete according to claim 4, wherein Dilute the anti-corrosion and water-repellent agent with water at 2% - 5% and then soak the wooden aggregate.

8. A cement-based woody permeable concrete according to claim 1, characterized in that, Preferably, the time for soaking the wooden aggregate in the anti-corrosion and water-repellent agent is 1 - 15 days.

9. A preparation method of the cement woody permeable concrete according to claim 1, characterized in that, The method includes the following steps: Step 1: Preparation of wood-soaked aggregate Soak the wooden aggregate in the anti-corrosion and water-repellent agent for 1 - 15 days, fish it out and dry it to obtain the wood-soaked aggregate. Among them, the ratio of the anti-corrosion and water-repellent agent is that the weight ratio of wood vinegar liquid, chitosan, and sodium alginate is (10 - 100): (1 - 5): (0.5 - 1). Dilute the anti-corrosion and water-repellent agent with water at 2% - 5% and then soak the wooden aggregate; Step 2: Preparation of cement-wood permeable concrete Spray the wood-soaked aggregate with water to moisten it, then add it to a concrete mixer, add cement and stir to make the moistened wood-soaked aggregate and cement form a cementitious state, and then add water and stir to obtain cement-wood permeable concrete.

10. The preparation method of a cement-based woody permeable concrete according to claim 9, characterized in that, The stirring time in Step 2 is 60 - 180 seconds.

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