Straw fiber recycled aggregate concrete filling block for composite dense rib plate and preparation method of straw fiber recycled aggregate concrete filling block

Abstract

The invention relates to the field of building materials, in particular to a straw fiber recycled aggregate concrete filling block for a composite dense rib plate and a preparation method of the straw fiber recycled aggregate concrete filling block. The straw fiber recycled aggregate concrete filling block is prepared from the following raw materials: 300 to 350 parts of cement, 1200 to 1300 parts of construction waste recycled aggregate, 50 to 100 parts of fly ash, 50 to 100 parts of silica powder, 10 to 20 parts of straw fiber, 5 to 10 parts of polyphenyl particles, 5 to 10 parts of a polycarboxylic acid water reducing agent, 0.1 to 1 part of a foaming agent and 180 to 220 parts of water. And waste is recycled, so that resources are saved, environmental pollution is reduced, and the requirement of sustainable development is met.

Description

Technical Field

[0001] The present invention relates to the field of building materials, and particularly to a straw fiber recycled aggregate concrete filling block for a composite ribbed slab and a preparation method thereof. Background Art

[0002] With the continuous advancement of economic development and urbanization, as the most widely used building material at present, concrete consumes a large amount of raw materials such as sand and stone. Some regions are already facing a serious shortage of aggregate resources. At the same time, the demolition of old buildings generates a large amount of waste construction waste. Recycling it to replace natural aggregate not only saves resources but also reduces environmental pollution, meeting the requirements of sustainable development.

[0003] As a new type of horizontal support structure, the ribbed slab is widely used as a building material, and related research has been relatively mature. However, there is no report on applying waste construction waste to the concrete filling block of the ribbed slab. Summary of the Invention

[0004] Object of the Invention: Aiming at the above technical problems, the present invention provides a straw fiber recycled aggregate concrete filling block for a composite ribbed slab and a preparation method thereof.

[0005] The technical solution adopted is as follows:

[0006] A straw fiber recycled aggregate concrete filling block for a composite ribbed slab is made from the following raw materials in parts by weight:

[0007] 300 - 350 parts of cement, 1200 - 1300 parts of construction waste recycled aggregate, 50 - 100 parts of fly ash, 50 - 100 parts of silica fume, 10 - 20 parts of straw fiber, 5 - 10 parts of polystyrene particles, 5 - 10 parts of polycarboxylate water reducer, 0.1 - 1 part of foaming agent, and 180 - 220 parts of water.

[0008] Further, the preparation method of the construction waste recycled aggregate is as follows:

[0009] The construction waste is crushed, magnetically separated, washed with water, and dried to obtain primary aggregate. Then, a polystyrene sulfonate film layer is coated on the surface of the primary aggregate by solution polymerization to obtain secondary aggregate. The nano-inorganic material is ultrasonically dispersed in an aqueous solution of poly(diallyldimethylammonium chloride), continuously stirred for 12 - 36 h, and then centrifuged to obtain modified nano-inorganic material. The secondary aggregate and the modified nano-inorganic material are added to anhydrous ethanol, continuously stirred for 1 - 10 h, and then the precipitate is collected and dried.

[0010] Further, the preparation method of the secondary aggregate is as follows:

[0011] Add styrene, divinylbenzene, and sodium styrene sulfonate to N-methylpyrrolidone. After fully stirring and dissolving, add primary aggregate and mix well. Then add a radical initiator, stir and heat up to 90 - 120 °C, react for 8 - 12 h, filter to collect the precipitate, wash with absolute ethanol, and dry.

[0012] Furthermore, the molar ratio of styrene to sodium styrene sulfonate is 1:1 - 10.

[0013] Furthermore, the nano-inorganic material is nano-silica.

[0014] Furthermore, the preparation method of the straw fiber is as follows:

[0015] Add crop straw with a length of 10 - 50 mm to sodium hydroxide solution and soak for 12 - 48 h. After soaking, filter, wash, and dry, then add to a silane coupling agent solution and impregnate for 1 - 5 h for modification treatment.

[0016] The above-mentioned crop straw is the general name of the mature crops such as the stems, leaves (ears) of wheat, rice, corn, potatoes, rapeseed, and cotton, which is characterized by a high crude fiber content (30% - 40%) and contains lignin, etc., and preferably rice straw.

[0017] Furthermore, the silane coupling agent solution is composed of a silane coupling agent, absolute ethanol, and deionized water with a mass ratio of 1:1:1 - 5.

[0018] Furthermore, the silane coupling agent is any one or a combination of two or more of KH-550, KH-560, and KH-570.

[0019] Furthermore, the foaming agent is a composition of an animal protein foaming agent and an anionic surfactant;

[0020] The mass ratio of the animal protein foaming agent to the anionic surfactant is 1:0.01 - 0.1.

[0021] Compared with plant protein foaming agents, animal protein foaming agents are more flexible in the water dilution ratio, and the foam generated by animal protein foaming agents is more closed, which makes the products made with animal protein foaming agents have better heat preservation, anti-seepage, and noise reduction properties.

[0022] An anionic surfactant refers to a surfactant in which the part that plays a surface-active role after ionization in water carries a negative charge. It can be divided into four categories: carboxylates, sulfonates, sulfate esters, and phosphate esters. Preferably, it is sodium bis(2-phenylethyl) sulfosuccinate. As a special double-chain anionic surfactant, it has a disulfonate hydrophilic group, is non-toxic, non-irritating, highly soluble in water, biodegradable, has strong hydrophilicity and emulsifying ability. It can cooperate with animal protein foaming agents to reduce the surface tension of the liquid, enhance the foaming activity, reduce the bubble pore size, and at the same time can also play a role in stabilizing the bubbles, increase the number of closed pores, and improve the mechanical strength of the concrete filling block.

[0023] The present invention also provides a preparation method for a concrete filling block with straw fiber recycled aggregate for a composite ribbed slab:

[0024] The foaming agent is mixed with part of the water and foamed by a foaming machine to obtain foam. Cement, recycled construction waste aggregate, fly ash, silica fume, straw fiber, and polystyrene particles are mixed evenly and then added to the remaining water in which the polycarboxylate water reducer has been pre-dissolved, and continuously stirred to obtain mortar. The foam and the mortar are mixed evenly and then poured into a mold and cured to a fixed age.

[0025] Advantages of the present invention:

[0026] The present invention provides a concrete filling block with straw fiber recycled aggregate for a composite ribbed slab. The waste construction waste still retains a certain amount of bonding mortar, and during demolition and crushing, it will also cause damage to the surface and inside of the aggregate, resulting in cracks. Direct use will affect the mechanical strength of the filling block. In this application, the sodium polystyrene sulfonate film layer on the surface of the secondary aggregate is negatively charged, and the surface of the modified nano-inorganic material is positively charged. Through the electrostatic-induced self-assembly of the two, the modified nano-inorganic material is adsorbed and filled in the surface and internal gaps of the aggregate, achieving the effect of improving aggregate regeneration and enhancing the overall mechanical properties;

[0027] As a reinforcing material, straw fiber can improve the toughness and ductility of the filling block, enabling it to withstand greater stress without damage. After being treated with a silane coupling agent, it is not easy to agglomerate, and the bonding force with cement and aggregate is enhanced, thereby further improving the mechanical strength of the filling block;

[0028] The anionic surfactant and the animal protein foaming agent can cooperate to reduce the surface tension of the liquid, enhance the foaming activity, reduce the bubble pore size, and at the same time can also play a role in stabilizing the bubbles, increase the number of closed pores, and improve the mechanical strength of the filling block. The straw fiber recycled aggregate concrete filling block provided by the present invention has high mechanical strength and heat preservation performance, and uses waste resources, which not only saves resources but also reduces environmental pollution, meeting the requirements of sustainable development. Description of the drawings

[0029] Figure 1SEM photograph of the straw fiber recycled aggregate concrete filling block prepared in Example 1. Detailed implementation mode

[0030] For those not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase. Technologies not mentioned in the present invention refer to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel tests and adopt the same treatment steps and parameters.

[0031] Cement: P·O42.5, Conch

[0032] Recycled construction waste aggregate: self-made

[0033] Fly ash: Class F Grade I, Shijiazhuang Niudong Mineral Products Co., Ltd.

[0034] Silica fume: Lingshou County Jianshi Mineral Powder Factory

[0035] Straw fiber: self-made

[0036] Polystyrene particles: 1 - 5 mm, Langfang Best Energy Saving Building Materials Co., Ltd.

[0037] Polycarboxylate superplasticizer: Sierbang Petrochemical

[0038] Animal protein foaming agent: Xiongguan

[0039] Sodium bis(2 - ethylhexyl) sulfosuccinate: Shandong Jubang Chemical Co., Ltd.

[0040] Water: tap water

[0041] Example 1:

[0042] This example provides a straw fiber recycled aggregate concrete filling block for composite ribbed slabs, which is made from the following raw materials in parts by weight:

[0043] 320 parts of cement, 1250 parts of recycled construction waste aggregate, 60 parts of fly ash, 60 parts of silica fume, 20 parts of straw fiber, 8 parts of polystyrene particles, 5 parts of polycarboxylate superplasticizer, 0.5 part of animal protein foaming agent, 0.02 part of sodium bis(2 - ethylhexyl) sulfosuccinate, and 200 parts of water.

[0044] Among them, the preparation method of the recycled construction waste aggregate is as follows:

[0045] The construction waste mainly composed of waste concrete and sintered clay bricks at a demolition site is crushed by a jaw crusher. After the crushed particles are removed of metals by a magnetic separator, they are washed with tap water to remove the attached soil and then dried to obtain primary aggregates with a particle size of 1 - 10 mm. 10.42 g (0.1 mol) of styrene, 2.5 g of divinylbenzene, and 185.57 g (0.9 mol) of sodium styrene sulfonate are added to 50 L of N-methylpyrrolidone. After being fully stirred and dissolved, 5 kg of primary aggregates are added and mixed evenly. 1 g of free radical initiator BPO is added, and the mixture is stirred and heated to 100 °C and reacted for 10 h. Then the precipitate is collected by filtration, washed thoroughly with absolute ethanol, and dried to obtain secondary aggregates. 1 kg of nano-silica is ultrasonically dispersed in 5000 ml of an aqueous solution of polydiallyldimethylammonium chloride with a mass concentration of 20%. After continuously stirring for 24 h, the modified nano-silica is obtained by centrifugation. The secondary aggregates and the modified nano-silica are added to 50 L of absolute ethanol, continuously stirred for 10 h, and then the precipitate is collected and dried.

[0046] The preparation method of the straw fiber is as follows:

[0047] The rice straw is crushed to a length of 10 - 50 mm, and then 100 g is taken and added to 1000 ml of a sodium hydroxide solution with a mass concentration of 5% and soaked for 24 h. After the soaking is completed, it is filtered out, washed with deionized water until neutral, and then dried. A silane coupling agent solution is prepared by mixing the silane coupling agent KH-570, absolute ethanol, and deionized water in a mass ratio of 1:1:3. Then the dried rice straw is added to 500 ml of the silane coupling agent solution and impregnated and modified at room temperature for 2 h, and then filtered out and dried.

[0048] The preparation method of the above composite ribbed slab filled with straw fiber recycled aggregate concrete blocks:

[0049] An animal protein foaming agent, sodium hexadecyl diphenyl ether disulfonate, and 10% by mass of water are mixed and foamed by a foaming machine to obtain foam. Cement, construction waste recycled aggregate, fly ash, silica fume, straw fiber, and polystyrene particles are mixed evenly, and then the remaining water in which a polycarboxylate water reducer is pre-dissolved is added, and continuously stirred for 5 min to obtain mortar. The foam and the mortar are stirred and mixed for 5 min and then poured into a mold and tamped to form. Demolding is carried out after 24 h, and curing is carried out under standard conditions for 28 d.

[0050] Example 2:

[0051] It is basically the same as Example 1, the difference is that, by weight, it is made from the following raw materials:

[0052] 350 parts of cement, 1300 parts of recycled construction waste aggregate, 100 parts of fly ash, 100 parts of silica fume, 20 parts of straw fiber, 10 parts of polystyrene particles, 5 parts of polycarboxylate superplasticizer, 0.5 part of animal protein foaming agent, 0.02 part of sodium bis(2-phenylethyl) sulfosuccinate, 220 parts of water.

[0053] Example 3:

[0054] Basically the same as Example 1, except that, by weight, it is made from the following raw materials:

[0055] 300 parts of cement, 1200 parts of recycled construction waste aggregate, 50 parts of fly ash, 50 parts of silica fume, 10 parts of straw fiber, 5 parts of polystyrene particles, 5 parts of polycarboxylate superplasticizer, 0.5 part of animal protein foaming agent, 0.02 part of sodium bis(2-phenylethyl) sulfosuccinate, 200 parts of water.

[0056] Comparative Example 1:

[0057] Basically the same as Example 1, except that primary aggregate is directly used instead of recycled construction waste aggregate.

[0058] Comparative Example 2:

[0059] Basically the same as Example 1, except that the primary aggregate and nano-silica are directly mixed and stirred without treatment.

[0060] The preparation method of the recycled construction waste aggregate is as follows:

[0061] The construction waste mainly composed of waste concrete and sintered clay bricks at a demolition site is crushed by a jaw crusher. After the crushed particles are removed of metals by a magnetic separator, they are washed with tap water to remove the attached soil and then dried to obtain primary aggregate with a particle size of 1 - 10 mm. 5 kg of the primary aggregate and 1 kg of nano-silica are added to 50 L of absolute ethanol, continuously stirred for 10 h, and then the precipitate is collected and dried.

[0062] Comparative Example 3:

[0063] Basically the same as Example 1, except that the primary aggregate and nano-silica are directly mixed and stirred without treatment and then evaporated to dryness.

[0064] The preparation method of the recycled construction waste aggregate is as follows:

[0065] The construction waste mainly composed of waste concrete and sintered clay bricks at a demolition site was crushed by a jaw crusher. After the crushed particles were removed of metals by a magnetic separator, the attached soil was removed by washing with tap water and then dried to obtain primary aggregates with a particle size of 1-10 mm. 5 kg of primary aggregates and 1 kg of nano-silica were added to 50 L of absolute ethanol. After continuous stirring for 10 h, the absolute ethanol was evaporated by heating to 80 °C, and the precipitate was collected.

[0066] Comparative Example 4:

[0067] It is basically the same as Example 1, except that the straw fiber is not impregnated and modified with a silane coupling agent solution during preparation.

[0068] The preparation method of the straw fiber is as follows:

[0069] The rice straw was crushed to a length of 10-50 mm, then 100 g was taken and added to 1000 ml of a sodium hydroxide solution with a mass concentration of 5% and soaked for 24 h. After soaking, it was filtered out, washed with deionized water until neutral, and then dried.

[0070] Comparative Example 5:

[0071] It is basically the same as Example 1, except that sodium hexadecyl diphenyl ether disulfonate is not added.

[0072] Performance test:

[0073] The straw fiber recycled aggregate concrete filling blocks prepared in Examples 1-3 and Comparative Examples 1-5 were made into specimens for performance testing:

[0074] According to the "Standard Test Method for Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), relevant mechanical property tests were carried out. The specimen size for the compressive strength test was 100 mm × 100 mm × 100 mm, and the specimen size for the flexural strength test was 40 mm × 40 mm × 160 mm. The thermal conductivity was tested according to the standard of "Determination of Steady-State Thermal Resistance and Related Characteristics of Thermal Insulation Materials - Heat Flow Meter Method" (GB / T10295-2008). The test results are shown in Table 1 below:

[0075] Table 1:

[0076]

[0077] As can be seen from Table 1 above, the straw fiber recycled aggregate concrete filling blocks prepared by the present invention have high mechanical strength and heat insulation performance;

[0078] By comparing Example 1 with Comparative Examples 1-3, it can be seen that the recycled construction waste aggregate prepared by the method of the present invention has certain advantages compared with the general recycling method, and the performance of the straw fiber recycled aggregate concrete filling block is greatly improved;

[0079] By comparing Example 1 with Comparative Example 4, it can be seen that the straw fiber prepared by the method of the present invention has a better strengthening and toughening effect;

[0080] By comparing Example 1 with Comparative Example 5, it can be seen that the addition of sodium hexadecyl diphenyl ether disulfonate plays a positive role in improving the performance of the straw fiber recycled aggregate concrete filling block.

[0081] The above examples are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A straw fiber recycled aggregate concrete filling block for a composite ribbed slab, characterized in that, It is made from the following raw materials by weight: 300-350 parts of cement, 1200-1300 parts of recycled aggregate from construction waste, 50-100 parts of fly ash, 50-100 parts of silica powder, 10-20 parts of straw fiber, 5-10 parts of polystyrene particles, 5-10 parts of polycarboxylic acid water reducer, 0.1-1 parts of foaming agent, and 180-220 parts of water.

2. The straw fiber recycled aggregate concrete filling block for the composite ribbed slab according to claim 1, wherein The preparation method of the construction waste recycled aggregate is as follows: The construction waste is crushed, magnetically separated, washed and dried to obtain primary aggregate, and then a sodium polystyrene sulfonate film is coated on the surface of the primary aggregate by solution polymerization to obtain secondary aggregate, and the nano-inorganic material is ultrasonically dispersed in an aqueous solution of polydiallyldimethylammonium chloride, and the modified nano-inorganic material is obtained by centrifugation after continuous stirring for 12-36 hours, and the secondary aggregate and the modified nano-inorganic material are added to anhydrous ethanol, and the precipitate is collected and dried after continuous stirring for 1-10 hours.

3. The straw fiber recycled aggregate concrete filling block for a composite ribbed slab according to claim 2, wherein, The preparation method of the secondary aggregate is as follows: Add styrene, divinylbenzene and sodium styrene sulfonate to N-methylpyrrolidone, stir thoroughly to dissolve, add primary aggregate and mix well, add free radical initiator, stir and heat to 90-120℃, react for 8-12h, filter and collect the precipitate, wash with anhydrous ethanol and dry.

4. The straw fiber recycled aggregate concrete filling block for composite ribbed slab according to claim 3, characterized in that, The molar ratio of styrene to sodium styrene sulfonate is 1:1-10.

5. The straw fiber recycled aggregate concrete filling block for composite ribbed slab according to claim 3, characterized in that, The nano inorganic material is nano silicon dioxide.

6. The straw fiber recycled aggregate concrete filling block for the composite ribbed slab according to claim 1, characterized in that, The preparation method of the straw fiber is as follows: The crop straw with a length of 10-50 mm is added to a sodium hydroxide solution and soaked for 12-48 hours. After the soaking is completed, it is filtered out, washed, and dried, and then added to a silane coupling agent solution for immersion modification treatment for 1-5 hours.

7. The straw fiber recycled aggregate concrete filling block for composite ribbed slab according to claim 6, characterized in that, The silane coupling agent solution consists of a silane coupling agent, anhydrous ethanol and deionized water in a mass ratio of 1:1:1-5.

8. The straw fiber recycled aggregate concrete filling block for composite ribbed slab according to claim 6, characterized in that, The silane coupling agent is any one of KH-550, KH-560, and KH-570, or a combination of two or more thereof.

9. The straw fiber recycled aggregate concrete filling block for composite ribbed slab according to claim 1, characterized in that, The foaming agent is a composition of an animal protein foaming agent and an anionic surfactant; The mass ratio of the animal protein foaming agent to the anionic surfactant is 1:0.01-0.

1.

10. The method for preparing the straw fiber recycled aggregate concrete filling block for composite multi-ribbed slab according to any one of claims 1 to 9, characterized in that: The foaming agent and part of the water are mixed and foamed by a foaming machine to obtain foam. The cement, recycled aggregate from construction waste, fly ash, silica powder, straw fiber and polystyrene particles are evenly mixed, and the remaining water in which the polycarboxylic acid water-reducing agent is pre-dissolved is added, and the mortar is obtained by continuous stirring. The foam and mortar are mixed evenly and then poured into a mold for molding and cured to a fixed age.

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