CN107777981A - A kind of regeneration concrete and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of building materials, in particular to a recycled concrete and a preparation method thereof. The recycled concrete provided by the invention is made of the following raw materials by weight: 1000-1300 parts of recycled crushed stone; 400-600 parts of sand; 100-500 parts of slag powder; 100-500 parts of fly ash; alkali metal hydroxide 15-25 parts; 60-75 parts of alkali metal silicate; 240-260 parts of water; 5-10 parts of retarding superplasticizer. The invention uses regenerated crushed stone and sand as aggregates, and uses industrial by-products such as slag powder and fly ash as a cementitious material binder after alkali excitation to obtain a concrete material that is environmentally friendly and has excellent performance. The concrete material not only realizes the effective reuse of abandoned buildings and industrial waste, but also has the advantages of fast setting time and high early strength, which is conducive to popularization and application in disaster relief and national defense construction.

Description

A kind of recycled concrete and its preparation method

technical field

The invention belongs to the field of building materials, in particular to a recycled concrete and a preparation method thereof.

Background technique

With the continuous development of the economy, the traditional construction industry has reached an unprecedented scale. On the one hand, it has greatly accelerated the urbanization process in China, but on the other hand, high energy consumption, high pollution, high waste, and extensive on-site people The industry has brought extremely serious negative impacts on ecology, cities, and industrial structure.

Construction waste often occurs in the reconstruction and demolition of old buildings in urbanization, the demolition and maintenance of municipal facilities, and the remaining waste at construction sites or building component factories, of which a considerable proportion is waste concrete. The traditional waste concrete treatment method is mainly to transport it to the suburbs for stacking or landfill, which not only costs a lot of freight, but also takes up a lot of valuable land resources and causes secondary pollution to the environment. At the same time, at present, we mainly use ordinary Portland cement. In the process of its production, due to the calcination of limestone and the combustion of fossil fuels, a large amount of carbon dioxide will be produced. With the increase of warming substances such as CO ₂ in the atmosphere, Warming the earth's climate, leading to the greenhouse effect. Fly ash is the fine ash collected from the flue gas after coal combustion. Its storage not only takes up a lot of land, but also causes serious environmental pollution. Slag is a molten material mainly composed of calcium aluminosilicate obtained from blast furnace ironmaking, and its large-scale stockpiling will inevitably cause pollution and harm to air, soil, and water systems. For a long time, how to correctly dispose of abandoned buildings and these two kinds of industrial solid wastes has been the focus of the sustainable development of the national economy.

In addition, in the development of construction industrialization, construction units and construction units strongly require concrete to have higher early strength and shorter setting time to meet the requirements of the project cycle. Therefore, how to improve the early strength of concrete and shorten the setting time of concrete is an urgent industry problem to be solved.

Contents of the invention

In view of this, the purpose of the present invention is to provide a recycled concrete and its preparation method. The recycled concrete provided by the present invention realizes the resource utilization of construction waste, and has the advantages of fast setting time and high early strength.

The invention provides a kind of recycled concrete, which is made of raw materials including the following parts by weight:

Preferably, the recycled gravel includes recycled gravel with a particle size of 5-10 mm and recycled gravel with a particle size of 10-20 mm.

Preferably, the mass ratio of the regenerated crushed stone with a particle diameter of 5-10 mm to the regenerated crushed stone with a particle diameter of 10-20 mm is 1:(0.5-2).

Preferably, the apparent density of the regenerated gravel is 2000-3000kg/m ³ ; the bulk density of the regenerated gravel is 1000-1200kg/m ³ ; the water absorption of the regenerated gravel is 4-8%; The crushing index of the regenerated gravel is 15-20%.

Preferably, the specific gravity of the sand is 2-3; the fineness modulus of the sand is 2-3.

Preferably, the specific surface area of the slag powder is 300-500m ² /kg; the density of the slag powder is 2-3g/cm ³ .

Preferably, the specific surface area of the fly ash is 500-700m ² /kg; the density of the fly ash is 2-3g/cm ³ .

Preferably, in parts by weight, the raw materials include the following components:

The water content of the sodium hydroxide aqueous solution is 70-80 wt %; the water content of the sodium silicate aqueous solution is 60-70 wt %.

The present invention provides a method for preparing recycled concrete described in the above technical solution, comprising the following steps:

a), mixing recycled crushed stone, sand, slag powder, fly ash, alkali metal hydroxide, alkali metal silicate, water and retarding water reducer to obtain concrete slurry;

b), the concrete slurry is cured and cured to obtain recycled concrete.

Preferably, said step a) specifically includes:

a1), mixing part of the water with alkali metal hydroxide and alkali metal silicate respectively to obtain an aqueous alkali metal hydroxide solution and an aqueous alkali metal silicate solution;

a2), mixing the regenerated crushed stone with the remaining amount of water to obtain the first mixture;

a3), mixing the first mixture with slag powder, fly ash and sand to obtain a second mixture;

a4) Mixing the second mixture, an aqueous alkali metal hydroxide solution, an aqueous alkali metal silicate solution and a retarding superplasticizer to obtain a concrete slurry.

Compared with the prior art, the invention provides a recycled concrete and a preparation method thereof. The recycled concrete provided by the invention is made of the following raw materials by weight: 1000-1300 parts of recycled crushed stone; 400-600 parts of sand; 100-500 parts of slag powder; 100-500 parts of fly ash; alkali metal hydroxide 15-25 parts; 60-75 parts of alkali metal silicate; 240-260 parts of water; 5-10 parts of retarding superplasticizer. The invention uses regenerated crushed stone and sand as aggregates, and uses industrial by-products such as slag powder and fly ash as a cementitious material binder after alkali excitation to obtain a concrete material that is environmentally friendly and has excellent performance. The concrete material not only realizes the effective reuse of abandoned buildings and industrial waste, but also has the advantages of fast setting time and high early strength, which is conducive to popularization and application in disaster relief and national defense construction. Experimental results show that the 7-day compressive strength of the recycled concrete provided by the invention exceeds 55 MPa, the initial setting time is 17-28 minutes, and the final setting time is 38-53 minutes.

Detailed ways

The following clearly and completely describes the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The invention provides a kind of recycled concrete, which is made of raw materials including the following parts by weight:

The recycled concrete provided by the invention includes recycled gravel, sand, slag powder, fly ash, alkali metal hydroxide, alkali metal silicate, water and retarding water reducer. Wherein, the regenerated gravel is crushed material of waste concrete; the regenerated gravel preferably includes regenerated gravel with a particle size of 5-10 mm and regenerated gravel with a particle size of 10-20 mm; the regenerated gravel with a particle size of 5-10 mm The mass ratio of gravel to recycled gravel with a particle size of 10-20mm is preferably 1:(0.5-2), more preferably 1:1; the apparent density of the recycled gravel is preferably 2000-3000kg/m ³ , Specifically, it can be 2100kg/m ³ , 2200kg/m ³ , 2300kg/m ³ , 2400kg/m ³ , 2500kg/m ³ , 2519kg/m ³ , 2600kg/m ^{3 , 2700kg/m 3 ,} 2800kg/m ³ or 2900kg/m 3 m ³ ; the bulk density of the recycled gravel is preferably 1000-1200kg/m ³ , specifically 1050kg/m ³ , 1100kg/m ³ , 1150kg/m ³ , 1187kg/m ³ or 1190kg/m ³ ; the The water absorption rate of the regenerated gravel is preferably 4-8%, specifically 4%, 5%, 6%, 7% or 8%; the crushing index of the regenerated gravel is preferably 15-20%, specifically can be 15%, 16%, 17%, 17.5%, 18%, 19% or 20%; the recycled crushed stone preferably conforms to continuous gradation. In the present invention, the content of the recycled gravel in the raw material is 1000-1300 parts by weight, specifically 1010 parts by weight, 1020 parts by weight, 1030 parts by weight, 1038 parts by weight, 1040 parts by weight, 1050 parts by weight, 1060 parts by weight Parts by weight, 1070 parts by weight, 1080 parts by weight, 1090 parts by weight, 1100 parts by weight, 1110 parts by weight, 1120 parts by weight, 1130 parts by weight, 1140 parts by weight, 1150 parts by weight, 1155 parts by weight, 1160 parts by weight, 1170 parts by weight , 1180 parts by weight, 1190 parts by weight, 1200 parts by weight, 1210 parts by weight, 1220 parts by weight, 1225 parts by weight, 1230 parts by weight, 1240 parts by weight, 1250 parts by weight, 1260 parts by weight, 1270 parts by weight, 1280 parts by weight, 1290 parts by weight or 1300 parts by weight.

In the present invention, the sand is preferably river sand; the specific gravity of the sand is preferably 2 to 3, specifically 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.69, 2.7, 2.8, 2.9 or 3; The fineness modulus of the sand is preferably 2-3, specifically 2.1, 2.2, 2.3, 2.4, 2.5, 2.52, 2.6, 2.7, 2.8, 2.9 or 3; the sand preferably conforms to continuous gradation. In the present invention, the content of the sand in the raw material is 400-600 parts by weight, specifically 405 parts by weight, 410 parts by weight, 415 parts by weight, 420 parts by weight, 425 parts by weight, 430 parts by weight, and 435 parts by weight , 440 parts by weight, 445 parts by weight, 450 parts by weight, 455 parts by weight, 460 parts by weight, 465 parts by weight, 470 parts by weight, 475 parts by weight, 480 parts by weight, 485 parts by weight, 490 parts by weight, 495 parts by weight, 500 parts by weight Parts by weight, 505 parts by weight, 510 parts by weight, 515 parts by weight, 520 parts by weight, 525 parts by weight, 530 parts by weight, 535 parts by weight, 540 parts by weight, 545 parts by weight, 550 parts by weight, 555 parts by weight, 560 parts by weight , 565 parts by weight, 570 parts by weight, 575 parts by weight, 580 parts by weight, 585 parts by weight, 590 parts by weight, 595 parts by weight or 600 parts by weight.

In the present invention, the specific surface area of the slag powder is preferably 300-500m ² /kg, specifically 320m ² /kg, 340m ² /kg, 360m ² /kg, 380m ² /kg, 400m ² /kg, 420m 2 /kg ² /kg, 440m ² /kg, 460m ² /kg, 480m ² /kg or 500m ² /kg; the density of the slag powder is 2-3g/cm ³ , specifically 2.1g/cm ³ , 2.2g/cm 3 cm ³ , 2.3g/cm ³ , 2.4g/cm ³ , 2.5g/cm ³ , 2.6g/cm ³ , 2.7g/cm ³ , 2.8g/cm ³ , 2.9g/cm ³ or 3g/cm ³ ; The loss on ignition of the slag powder is preferably ≤3%; the slag powder preferably meets the requirements of the national standard "Mineral Admixtures for High-Strength and High-Performance Concrete" GB/T 18736-2002. In the present invention, the content of the slag powder in the raw material is 100-500 parts by weight, specifically 100 parts by weight, 150 parts by weight, 200 parts by weight, 250 parts by weight, 260 parts by weight, 270 parts by weight, 280 parts by weight Parts, 290 parts by weight, 300 parts by weight, 310 parts by weight, 320 parts by weight, 330 parts by weight, 340 parts by weight, 350 parts by weight, 360 parts by weight, 370 parts by weight, 375 parts by weight, 380 parts by weight, 390 parts by weight, 400 parts by weight, 450 parts by weight or 500 parts by weight. In the present invention, the slag powder has higher potential activity and can improve the mechanical properties of concrete, and its gelling activity is higher than that of fly ash.

In the present invention, the fly ash is recovered from industrial dust produced after coal combustion; the fineness of the fly ash is preferably 400-1000 mesh, specifically 400 mesh, 450 mesh, 500 mesh mesh, 550 mesh, 600 mesh, 650 mesh, 700 mesh, 750 mesh, 800 mesh, 850 mesh, 900 mesh or 950 mesh; the specific surface area of the fly ash is preferably 500-700m ² /kg, specifically 520m ² /kg, 540m ² /kg, 560m ² /kg, 580m ² /kg, 600m ² /kg, 620m ² /kg, 640m ² /kg, 660m ² /kg, 680m ² /kg or 700m ² /kg; The density of the fly ash is 2-3g/cm ³ , specifically 2.1g/cm ³ , 2.2g/cm ³ , 2.3g/cm ³ , 2.34g/cm ³ , 2.4g/cm ³ , 2.5g/cm 3 , 2.5g/cm 3 cm ³ , 2.6g/cm ³ , 2.7g/cm ³ , 2.8g/cm ³ , 2.9g/cm ³ or 3g/cm ³ ; the loss on ignition of the fly ash is preferably ≤3%, more preferably ≤2.34 %; The fly ash preferably meets the requirements of the national standard "Mineral Admixtures for High-Strength and High-Performance Concrete" GB/T18736-2002. In the preferred technical solution of the present invention, fly ash with a small particle size can be used for filling and compacting, and the homogeneity and compactness of concrete can also be improved. In the present invention, the content of the fly ash in the raw material is 100 to 500 parts by weight, specifically 100 parts by weight, 105 parts by weight, 110 parts by weight, 115 parts by weight, 120 parts by weight, 125 parts by weight, 130 parts by weight Parts by weight, 135 parts by weight, 140 parts by weight, 145 parts by weight, 150 parts by weight, 160 parts by weight, 167 parts by weight, 170 parts by weight, 200 parts by weight, 250 parts by weight, 300 parts by weight, 350 parts by weight, 400 parts by weight , 450 parts by weight or 500 parts by weight.

In the present invention, the alkali metal hydroxide is sodium hydroxide and/or potassium hydroxide; the content of the alkali metal hydroxide in the raw material is 15 to 25 parts by weight, specifically 15 parts by weight, 16 parts by weight Parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight or 25 parts by weight.

In the present invention, the alkali metal silicate is sodium silicate and/or potassium silicate; the content of the alkali metal silicate in the raw material is 60 to 75 parts by weight, specifically 60 parts by weight, 61 parts by weight Parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight , 74 parts by weight or 75 parts by weight.

In the present invention, the content of the water in the raw material is 240 to 260 parts by weight, specifically 240 parts by weight, 241 parts by weight, 242 parts by weight, 243 parts by weight, 244 parts by weight, 245 parts by weight, and 246 parts by weight , 247 parts by weight, 248 parts by weight, 249 parts by weight, 250 parts by weight, 251 parts by weight, 252 parts by weight, 253 parts by weight, 254 parts by weight, 255 parts by weight, 256 parts by weight, 257 parts by weight, 258 parts by weight, 259 parts by weight parts by weight or 260 parts by weight.

In an embodiment provided by the present invention, part of the water in the raw material is firstly combined with alkali metal hydroxide and alkali metal silicate to form an aqueous alkali metal hydroxide solution and an aqueous alkali metal silicate solution, and the remaining water is used as a raw material alone components. Wherein, the water content of the alkali metal hydroxide aqueous solution is preferably 70-80wt%, specifically 71wt%, 72wt%, 73wt%, 74wt%, 74.9wt%, 75wt%, 76wt%, 77wt%, 78wt% , 79wt% or 80wt%; the content of the alkali metal hydroxide aqueous solution in the raw material is preferably 75 to 80 parts by weight, specifically 75 parts by weight, 76 parts by weight, 77 parts by weight, 77.5 parts by weight, 78 parts by weight , 78.5 parts by weight, 79 parts by weight or 80 parts by weight; the water content of the alkali metal silicate aqueous solution is preferably 60 to 70wt%, specifically 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt% %, 66wt%, 67wt%, 68wt%, 69wt% or 70wt%; the content of the alkali metal silicate aqueous solution in the raw material is preferably 190 to 200 parts by weight, specifically 190 parts by weight, 191 parts by weight, 192 parts by weight Parts by weight, 193 parts by weight, 193.8 parts by weight, 194 parts by weight, 195 parts by weight, 196 parts by weight, 197 parts by weight, 198 parts by weight, 199 parts by weight or 200 parts by weight; the content of the balance of water in the raw material Preferably 62 to 74 parts by weight, specifically 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 69.3 parts by weight, 70 parts by weight , 71 parts by weight, 72 parts by weight, 73 parts by weight, 73.5 parts by weight or 74 parts by weight.

In the present invention, the retarded water reducer is preferably calcium sugar; the pH of the retarded water reducer is preferably 11 to 13, specifically 12; the water reducing rate of the retarded water reducer is preferably 5 ~10%, specifically 8%; the air content of the retarded superplasticizer is preferably 2-4%, specifically 2.9%; the shrinkage ratio of the retarded superplasticizer is preferably ≤100%. In the present invention, the content of the retarding superplasticizer in the raw material is 5 to 10 parts by weight, specifically 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight Parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight or 10 parts by weight.

The present invention also provides a method for preparing recycled concrete described in the above technical solution, comprising the following steps:

a), mixing recycled crushed stone, sand, slag powder, fly ash, alkali metal hydroxide, alkali metal silicate, water and retarding water reducer to obtain concrete slurry;

b), the concrete slurry is cured and cured to obtain recycled concrete.

In the preparation method provided by the present invention, at first each raw material component is mixed to prepare concrete slurry, and specific process comprises:

a1), mixing part of the water with alkali metal hydroxide and alkali metal silicate respectively to obtain an aqueous alkali metal hydroxide solution and an aqueous alkali metal silicate solution;

a2), mixing the regenerated crushed stone with the remaining amount of water to obtain the first mixture;

a3), mixing the first mixture with slag powder, fly ash and sand to obtain a second mixture;

a4) Mixing the second mixture, an aqueous alkali metal hydroxide solution, an aqueous alkali metal silicate solution and a retarding superplasticizer to obtain a concrete slurry.

In the preparation method of the above-mentioned concrete slurry provided by the present invention, in step a2), the mixing method is preferably stirring, and the mixing time is preferably 2 to 10 minutes, more preferably 5 minutes; in step a3), the mixing method is preferably Stirring, the mixing time is preferably 2 to 10 minutes, more preferably 5 minutes; in step a4), the mass ratio of the alkali metal hydroxide aqueous solution to the alkali metal silicate aqueous solution is preferably 1:2.5; the mixing method is preferably stirring, The mixing time is preferably 0.5 to 5 minutes, more preferably 2 minutes.

After the concrete slurry is obtained, the concrete slurry is solidified and maintained to obtain recycled concrete materials. In an embodiment provided by the invention, the concrete slurry can be solidified and maintained in the following manner:

Pour the concrete slurry into the plastic mold and vibrate it compactly. Cover it with plastic film on the first day, and then pour water on the plastic film, preferably twice a day; Put it into the high-temperature steam rapid curing box, the curing temperature is preferably 75-85°C, more preferably 80°C; the curing time is preferably 12-36h, more preferably 24h; after the high-temperature steam curing is completed, the concrete specimen is removed from the high-temperature steam Take it out of the quick curing box and put it on the ground, pour water on the surface of the concrete specimen and the ground, cover it with a plastic film, and then pour water on the plastic film, preferably watering twice a day, and curing until the required time, preferably until the 7th day sky.

The recycled concrete provided by the invention and its preparation method have the following beneficial effects:

The slag powder used in the present invention has potential activity, can improve the strength of concrete, has the effect of micro-aggregate, and suppresses the shrinkage of concrete. As an independent component of concrete, slag powder is not only beneficial to hydration and improving compactness, but also It can reduce the porosity and improve the pore structure, thereby improving the impermeability of hardened concrete.

The fly ash used in the present invention is recovered from the industrial dust produced after coal combustion, has a wide range of sources, has extremely strong pozzolanic properties, and can rapidly generate calcium silicate compound (C-S-H) gel by hydration reaction with alkali solution , Improve the mechanical properties of concrete, such as compressive and flexural strength. At the same time, it has good acid corrosion resistance and durability, low shrinkage and low permeability, and has good volume stability during condensation hardening and use.

The present invention preferably uses a sodium hydroxide aqueous solution with a mass concentration of 25.1% and a sodium silicate solution with a mass concentration of 35% to mix uniformly according to a mass ratio of 1:2.5 as an alkali activator. At this concentration and ratio, the alkali activator It can well stimulate the activity of slag powder and fly ash, and improve the performance of the prepared concrete.

The invention uses regenerated crushed stone and sand as aggregates, and uses industrial by-products such as slag powder and fly ash as a cementitious material binder after alkali excitation to obtain a concrete material that is environmentally friendly and has excellent performance. The preparation process of the concrete material is simple, not only realizes the effective reuse of abandoned buildings and industrial waste, but also has the advantages of fast setting time and high early strength, which is conducive to popularization and application in emergency rescue and national defense construction. In addition, the recycled concrete material provided by the invention also has good acid and alkali corrosion resistance and durability, low shrinkage and low permeability.

Experimental results show that the 7-day compressive strength of the recycled concrete provided by the invention exceeds 55 MPa, the initial setting time is 17-28 minutes, and the final setting time is 38-53 minutes.

For more clarity, detailed description is given below through the following examples.

The materials involved in the embodiments of the present invention and comparative examples are specifically as follows:

The recycled crushed stones are produced by Shenzhen Lvfa Pengcheng Environmental Protection Technology Co., Ltd. They are recycled crushed stones with a particle size of 5-10mm and 10-20mm respectively. The mass ratio is 1:1, which conforms to continuous gradation, and the apparent density is 2519kg/ m ³ , bulk density 1187kg/m ³ , water absorption 6%, crushing index 17.5%, remove debris such as glass, sawdust, bricks, etc., wash with clean water, and dry naturally for use;

Granite crushed stone is used as the natural coarse aggregate, which are natural coarse aggregates with a particle size between 5-10mm and 10-20mm respectively, and the mass ratio is 1:1, which conforms to continuous gradation;

The river sand is made of continuously graded natural fine aggregate, with a specific gravity of 2.69 and a fineness modulus of 2.52;

The slag powder is produced by Guangdong Basic New Century Concrete Co., Ltd., with a specific surface area of 400m ² /kg, a density of 2.8g/cm ³ , and an ignition loss of no more than 3%;

Fly ash is produced by Gongyi No. 2 Power Plant, with a specific surface area of 600m ² /kg, a density of 2.34g/cm ³ , a loss on ignition of no more than 3%, and a fineness of 600 mesh;

The cement is Shijing brand ordinary Portland cement with a strength grade of 42.5R;

The NaOH solution is prepared by titration of 99% pure white needle-like solid produced by Tianjin Botian Chemical Co., Ltd., the concentration of the substance is 8mol/L, the density is 1.275g/cm ³ , and the mass percent of sodium hydroxide is The concentration is 25.1%, and the concentration of water content is 74.9%;

The Na ₂ SiO ₃ solution is produced by Foshan Nanhai Coning Chemical Co., Ltd., with a modulus of 3.34, a density of 1.387g/cm ³ , a sodium oxide content of 7.3%, a silicon dioxide content of 27.6%, and a water content of 65% by mass;

The slow-setting superplasticizer is produced by Sichuan Miyihuasen Sugar Industry Co., Ltd. Its appearance is brownish yellow powder, PH value is 12, water reducing rate is 8%, air content is 2.9%, and shrinkage ratio is ≤110%.

Example 1

Add 1155kg of continuously graded regenerated crushed stones with a particle size of 5-10mm and 10-20mm (mixed at a mass ratio of 1:1), 69.3kg of additional water, and stir for 5 minutes in a forced mixer; add 375kg of slag powder, powder 125kg of coal ash, 495kg of river sand, stirring for 5 minutes; adding 77.51kg of sodium hydroxide solution, 193.77kg of sodium silicate solution, 7.5kg of retarding superplasticizer, and stirring for 2 minutes to obtain concrete slurry 1.

Pour the slurry into a standard plastic mold and vibrate it compactly. On the first day, the ground is watered, and the mold filled with concrete slurry is placed on the ground, covered with a plastic film, and then watered on the plastic film, watered twice a day; Remove the formwork in two days, and immediately put the concrete specimen into the high-temperature steam rapid curing box after removing the formwork, the curing temperature is 80°C, and the curing time is 24h; Take it out and put it on the ground, then pour water directly on the surface of the concrete specimen and the ground, then cover it with a plastic film, pour water on the plastic film, water twice a day, and cure until the seventh day to obtain slag of 150mm*150mm*150mm - Fly ash based geopolymer recycled concrete specimens.

Example 2

Add 1225kg of regenerated crushed stones (mixed according to the mass ratio of 1:1) and 73.5kg of additional water into the forced mixer, and the mixing time is 5 minutes; add 300kg of slag powder, powder 100kg of coal ash, 525kg of river sand, stirring for 5 minutes; adding 77.51kg of sodium hydroxide solution, 193.77kg of sodium silicate solution, 6kg of retarding superplasticizer, and stirring for 2 minutes to obtain concrete slurry 2. The curing method refers to Example 1, and a slag-fly ash based geopolymer recycled concrete specimen of 150mm*150mm*150mm is obtained.

Example 3

Add 1038kg of continuously graded regenerated crushed stones with a particle size of 5-10mm and 10-20mm (mixed at a mass ratio of 1:1), 62.3kg of additional water, and stir for 5 minutes in a forced mixer; add 500kg of slag powder, powder 167kg of coal ash, 445kg of river sand, stirring for 5 minutes; adding 77.51kg of sodium hydroxide solution, 193.77kg of sodium silicate solution, 10kg of retarding superplasticizer, and stirring for 2 minutes to obtain concrete slurry 3. The curing method refers to Example 1, and a slag-fly ash based geopolymer recycled concrete specimen of 150mm*150mm*150mm is obtained.

Comparative example 1

Comparative example 1 was prepared according to the conventional concrete preparation method, specifically adding 1155 kg of regenerated crushed stones (mixed at a mass ratio of 1:1) with a particle size of 5 to 10 mm and a continuous gradation of 10 to 20 mm in a forced mixer, and 69.3 kg of additional water, The mixing time is 5 minutes; 500kg of cement and 495kg of river sand are added, and the mixing time is 5 minutes; 184kg of water, 7.5kg of retarding superplasticizer are added, and the mixing time is 2 minutes, and the comparison concrete slurry 1 is obtained. Referring to Example 1 for the curing method, a comparative concrete specimen of 150mm*150mm*150mm was obtained.

Comparative example 2

Prepare comparative example 2 according to the conventional concrete preparation method, specifically add 1155 kg of natural coarse aggregate (mixed according to the mass ratio 1:1) with a particle size of 5 to 10 mm and a continuous gradation of 10 to 20 mm in a forced mixer, and add 69.3 kg of water , the stirring time is 5 minutes; add 500kg of cement, 495kg of river sand, and the stirring time is 5 minutes; add 184kg of water, 7.5kg of retarding superplasticizer, and the stirring time is 2 minutes, and the comparison concrete slurry 2 is obtained. Referring to Example 1 for the curing method, a comparative concrete specimen of 150mm*150mm*150mm was obtained.

Performance Testing

For the convenience of comparing the differences in the raw material consumption of different embodiments and comparative examples, the raw material consumption of each embodiment and comparative examples are summarized in Table 1 and Table 2 respectively:

Table 1 embodiment raw material consumption table

Table 2 Contrastive Raw Material Consumption Table

Note: 1. The additional water is to consider the characteristics of the high water absorption of the recycled coarse aggregate. In order to keep the water-binder ratio of the concrete unchanged, an additional additional water calculated by 6% of the mass of the recycled crushed stone is added;

2. Free water = NaOH solution mass × water percentage concentration 74.9% + Na ₂ SiO ₃ solution mass × water percentage concentration 65%;

3. Water-binder ratio = free water/slag powder + fly ash.

Carry out performance test to the sample that embodiment and comparative example obtain, described slump, setting time, compressive strength performance test method and instrument are respectively strictly according to GB/T-50080 " ordinary concrete mixture performance test method ", GB/T-50081 "Test Methods for Mechanical Properties of Ordinary Concrete" is implemented, and the data are shown in Table 3:

Table 3 performance test results

sample Slump (mm) Compressive strength (MPa) Initial setting time final setting time Example 1 210 67.4 21min 44min Example 2 130 55.3 28min 53min Example 3 110 74.1 17min 38min Comparative example 1 153 23.7 8h25min 10h40min Comparative example 2 166 34.2 8h45min 10h50min

As can be seen from the above experimental results, the slag-fly ash-based geopolymer recycled concrete prepared by the present invention has a slump of 110 to 210mm, belongs to fluid concrete or high fluid concrete, has good working performance, and is convenient for practical engineering Construction process operations such as pouring, vibrating, and plastering in applications. The 7d compressive strength is 55.3-74.1MPa, higher than the C55 concrete strength grade, and has a higher early strength. The initial setting time is 17-28 minutes, and the final setting time is 38-53 minutes. It has a relatively fast setting time, and its performance indicators are in line with the technical performance indicators of concrete.

Through the comparison of Example 1, Example 2, Example 3 and Comparative Example 1 and Comparative Example 2, it can be seen that the slag-fly ash base geopolymer recycled concrete of the present invention is better than ordinary Portland cement primary aggregate concrete and ordinary The strength of Portland cement recycled aggregate concrete is increased by 62% to 213%, the initial setting time is accelerated by 17 to 30 times, and the final setting time is accelerated by 11 to 16 times. It has the advantages of high early strength and fast setting time, which is conducive to popularization and application in emergency rescue and disaster relief and national defense construction.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. a kind of regeneration concrete, it is made up of the raw material including following parts by weight：

2. regeneration concrete according to claim 1, it is characterised in that the regeneration rubble includes 5~10mm's of particle diameter Regenerate 10~20mm of rubble and particle diameter regeneration rubble.

3. regeneration concrete according to claim 2, it is characterised in that the regeneration rubble and grain of the 5~10mm of particle diameter The mass ratio of 10~20mm of footpath regeneration rubble is 1:(0.5~2).

4. regeneration concrete according to claim 1, it is characterised in that the apparent density of the regeneration rubble for 2000~ 3000kg/m³；The bulk density of the regeneration rubble is 1000~1200kg/m³；The water absorption rate of the regeneration rubble for 4~ 8%；The crush index of the regeneration rubble is 15~20%.

5. regeneration concrete according to claim 1, it is characterised in that the proportion of the sand is 2~3；The sand it is thin It is 2~3 to spend modulus.

6. regeneration concrete according to claim 1, it is characterised in that the specific surface area of the slag powders be 300~ 500m²/kg；The density of the slag powders is 2~3g/cm³。

7. regeneration concrete according to claim 1, it is characterised in that the specific surface area of the flyash be 500~ 700m²/kg；The density of the flyash is 2~3g/cm³。

8. according to the regeneration concrete described in any one of claim 1~7, it is characterised in that in terms of parts by weight, the raw material Including following components：

The water content of the sodium hydrate aqueous solution is 70~80wt%；The water content of the sodium silicate aqueous solution be 60~ 70wt%.

9. the preparation method of regeneration concrete, comprises the following steps described in a kind of claim 1：

A), will regeneration rubble, sand, slag powders, flyash, alkali metal hydroxide, alkali silicate, water and retardation water reducing agent Mixing, obtains concrete slurry；

B), the concrete slurry obtains regeneration concrete by solidification and maintenance.

10. preparation method according to claim 9, it is characterised in that the step a) is specifically included：

A1), partial moisture is not mixed with alkali metal hydroxide and alkali silicate, respectively obtains alkali metal hydroxide The aqueous solution and alkali metal silicate aqueous solution；

A2), the water for regenerating rubble and surplus is mixed, obtains the first compound；

A3), first mixture is mixed with slag powders, flyash and sand, obtains the second compound；

A4), by the second compound, alkali metal hydroxide aqueous solution, alkali metal silicate aqueous solution and the retardation water reducing agent Mixing, obtains concrete slurry.