Activating treatment method for all components of waste concrete, regenerated and activated powder and application

Abstract

The invention discloses an activating treatment method for all components of waste concrete, regenerated and activated powder and application. The activating treatment method for the all components of the waste concrete comprises the following steps: crushing and grinding the all components of the waste concrete to obtain pretreated powder; the pretreated powder is subjected to low-temperature activation treatment and then cooled, and regenerated and activated powder is obtained. All the components of the waste concrete are subjected to surface activation modification, a large number of active nano-particles are generated on the surface of the powder, and interface bonding of the regenerated and activated powder, a new mineral admixture and cement paste is remarkably improved; and moreover, the traditional waste concrete treatment process is simplified by adopting an all-component crushing and screening treatment mode.

Description

Technical Field

[0001] The invention relates to the technical field of waste concrete recycling, and in particular to an activation treatment method for all components of waste concrete, a regenerated activated powder and an application thereof. Background Art

[0002] With the rapid advancement of global urbanization and the continuous development of the construction industry, the amount of construction waste is increasing. According to statistics, billions of tons of construction waste are generated every year around the world. If these waste concretes are not effectively disposed of and utilized, they will not only occupy a large amount of land resources, but may also have serious negative impacts on the environment, such as dust pollution and soil erosion. At the same time, the construction industry's demand for raw materials such as natural aggregates and cement is also growing, leading to over-exploitation of natural resources, further exacerbating environmental pressure. In this context, the development of waste concrete recycling technology has become an urgent problem to be solved, which can not only alleviate the environmental problems caused by waste disposal, but also reduce the consumption of natural resources, with significant economic and ecological benefits.

[0003] At present, the recycling of waste concrete mainly focuses on crushing and screening waste concrete to prepare recycled micro powder and recycled aggregate, and then use them to produce recycled concrete or apply them to road base and other fields. However, the performance of recycled aggregate and recycled concrete is often difficult to compare with natural aggregate and ordinary concrete. This is mainly because the cement paste and impurities remaining in the waste concrete have an adverse effect on the performance of recycled aggregate. In addition, the separation technology of recycled aggregate and recycled micro powder is still immature, which has hindered the recycling of waste concrete.

[0004] Therefore, it is urgent to develop new waste concrete treatment technologies, simplify the treatment process, expand the application scope of waste concrete, realize the high-value utilization of waste concrete, and promote the resource utilization of construction waste and the green development of the construction industry. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, propose an activation treatment method for all components of waste concrete, regenerated activated powder and application, and solve the technical problems of complex waste concrete treatment process and poor interface bonding of existing recycled aggregates in the prior art.

[0006] In a first aspect, the present invention provides a method for activating all components of waste concrete, comprising the following steps: Crushing and grinding all components of waste concrete to obtain pre-treated powder; The pretreated powder is subjected to low temperature activation treatment and then cooled to obtain regenerated activated powder.

[0007] In a second aspect, the present invention provides a regenerated activated powder, which is obtained by the activation treatment method of all components of waste concrete provided in the first aspect of the present invention.

[0008] In a third aspect, the present invention provides an application of the above-mentioned regenerated activated powder, wherein the regenerated activated powder is applied as a cementitious component in regenerated concrete.

[0009] Compared with the prior art, the beneficial effects of the present invention include: The present invention performs surface activation modification on all components of waste concrete, thereby producing a large number of active nanoparticles on the surface of the powder, significantly improving the interface bonding between the regenerated activated powder and new mineral admixtures and cement paste; moreover, the full-component crushing and screening treatment method simplifies the traditional waste concrete treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a 28d compressive strength diagram of recycled concrete test blocks F1-F13 obtained in Examples 1-5 of the present invention and Comparative Examples 1-8; Figure 2 This is a SEM image of the regenerated activated powder obtained in Example 6 of the present invention; Figure 3 This is a SEM image of the regenerated activated powder obtained in Comparative Example 9 of the present invention; Figure 4 This is a SEM image of the regenerated activated powder obtained in Comparative Example 10 of the present invention; Figure 5 This is a SEM image of the regenerated activated powder obtained in Comparative Example 11 of the present invention. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0012] In a first aspect, the present invention provides a method for activating all components of waste concrete, comprising the following steps: Crushing and grinding all components of waste concrete to obtain pre-treated powder; The pretreated powder is subjected to low temperature activation treatment and then cooled to obtain regenerated activated powder.

[0013] The present invention performs surface activation modification on all components of waste concrete, and a large number of active nanoparticles are generated on the surface of the powder, which significantly improves the interface bonding between the regenerated activated powder and the new mineral admixture and cement paste; moreover, the whole component crushing and screening treatment method simplifies the traditional waste concrete treatment process; in particular, different from the traditional method of regenerating aggregates, the present invention activates the surface of components such as calcium carbonate and gel in waste concrete, and the products such as free calcium oxide and highly active silica gel have significant gelling activity. At the same time, a large number of reaction products such as gel and calcium sulfonate fill the pores, optimize the reaction interface, and thus promote the strength development of recycled mixed concrete. Different from the traditional recycled concrete treatment process, the present invention expands the application scope of waste concrete.

[0014] In this embodiment, the particle size of the pretreated powder is ≤150 μm.

[0015] In this embodiment, the low-temperature activation treatment is performed by calcining the pretreated powder at a heating rate of 5-20°C / min, including but not limited to 5°C / min, 10°C / min, 15°C / min, 20°C / min, etc. The calcination temperature is 750-950°C, including but not limited to 750°C, 800°C, 850°C, 900°C, 950°C, etc. The calcination time is 0-10min, including but not limited to 0min, 2min, 4min, 6min, 8min, 10min, etc. The present invention controls the parameters of low activation within the above range, so that the obtained regenerated activated powder has a good activation effect. If the calcination temperature is too low, the activation effect on the powder is insufficient; if the calcination temperature is too high or the calcination time is too long, the activity will be greatly reduced.

[0016] In this embodiment, rapid cooling is adopted, and the rapid cooling process is: cooling to room temperature in 3-5 minutes.

[0017] In this embodiment, the rapid cooling method is fan rapid cooling.

[0018] In a second aspect, the present invention provides a regenerated activated powder, which is obtained by the activation treatment method of all components of waste concrete provided in the first aspect of the present invention.

[0019] In a third aspect, the present invention provides an application of the above-mentioned regenerated activated powder, wherein the regenerated activated powder is applied as a cementitious component in regenerated concrete.

[0020] Furthermore, the raw materials of the recycled concrete also include: cement and / or mineral admixtures.

[0021] Furthermore, the regenerated activated powder accounts for 0.1-100% of the total mass of the regenerated activated powder, cement and mineral admixtures, including but not limited to 0.1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc.

[0022] Furthermore, cement accounts for 0-99.9% of the total mass of the regenerated activated powder, cement and mineral admixtures, including but not limited to 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99.9%, etc.

[0023] Furthermore, the mineral admixture accounts for 0-99.9% of the total mass of the regenerated activated powder, cement and the mineral admixture, including but not limited to 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99.9% and the like.

[0024] Furthermore, the raw materials of the recycled concrete also include: aggregate.

[0025] Furthermore, the aggregate accounts for 0-70% of the total mass of the recycled activated powder, cement and mineral admixtures, including but not limited to 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.

[0026] Furthermore, the raw materials of the recycled concrete also include: a water reducing agent.

[0027] Furthermore, the water reducing agent is a polycarboxylate water reducing agent.

[0028] Furthermore, the solid content of the water reducing agent is 30%-50%, including but not limited to 30%, 35%, 40%, 45%, 50%, etc.

[0029] Furthermore, the water reducer accounts for 0.1%-5% of the total mass of the regenerated activated powder, cement and mineral admixtures, including but not limited to 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, etc.

[0030] Furthermore, the raw materials of the recycled concrete also include: water.

[0031] Furthermore, water accounts for 30%-50% of the total mass of the regenerated activated powder, cement and mineral admixtures.

[0032] To avoid redundancy, some of the raw materials in the following embodiments and comparative examples of the present invention are summarized as follows: The solid content of the polycarboxylate water-reducing agent used is 40%; The waste concrete used was obtained from the demolition of old buildings. After crushing and grinding, its chemical composition was determined by X-ray fluorescence spectrometer (Zetium, Malvern Panalytics). The test results are shown in Table 1.

[0033] Table 1 Physical and chemical analysis of waste concrete

[0034] Example 1 A method for preparing recycled concrete comprises the following steps: Select waste concrete, crush and grind it into powder with a particle size of ≤150μm, calcine the powder in a drum calciner, heat it from room temperature to 900℃ at a heating rate of 10℃ / min, and then cool it to room temperature with a fan for 3-5min. Take 500g of the cooled sample, add 500g of slag, stir slowly for two minutes in a stirring pot to mix, then add 400g of water (water-binder ratio is 0.40) and 5g of water reducer and stir quickly for 3min to obtain a slurry, which is poured into a 40×40×40mm mold and subjected to a compressive performance test after standard curing for 28d, recorded as F1.

[0035] Example 2 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected and crushed into powder with a particle size of ≤150μm. The powder was calcined in a drum calciner, and the temperature was raised from room temperature to 900℃ at a heating rate of 10℃ / min, and then rapidly cooled by a fan and cooled to room temperature for 3-5min. 250g of the cooled sample was taken, 500g (PO425) cement and 250g slag were added, and the mixture was slowly stirred in a stirring pot for two minutes, and then 400g water (water-cement ratio of 0.40) and 5g water reducer were added and stirred quickly for 3min to obtain a slurry, which was poured into a 40×40×40mm mold. After standard curing for 28d, the compressive strength test was carried out and recorded as F2.

[0036] Example 3 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected and crushed into powder with a particle size of ≤150μm. The powder was calcined in a drum calciner, and the temperature was raised from room temperature to 900℃ at a heating rate of 10℃ / min, and then rapidly cooled by a fan and cooled to room temperature for 3-5min. 700g of the cooled sample was taken, 300g of slag was added, and the mixture was slowly stirred in a stirring pot for two minutes, then 400g of water (water-binder ratio of 0.40) and 5g of water reducer were added and stirred quickly for 3min to obtain a slurry, which was poured into a 40×40×40mm mold and subjected to a compressive performance test after standard curing for 28d, which was recorded as F3.

[0037] Example 4 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected and crushed into powder with a particle size of ≤150μm. The powder was calcined in a drum calciner, and the temperature was raised from room temperature to 750℃ at a heating rate of 10℃ / min, and then rapidly cooled by a fan and cooled to room temperature for 3-5min. 500g of the cooled sample was taken, 500g of slag was added, and the mixture was slowly stirred in a stirring pot for two minutes, and then 400g of water (water-binder ratio of 0.40) and 5g of water reducer were added and stirred quickly for 3min to obtain a slurry, which was poured into a 40×40×40mm mold and subjected to a compressive performance test after standard curing for 28d, which was recorded as F4.

[0038] Example 5 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected, crushed and ground into powder with a particle size of ≤150μm, and calcined in a drum calciner, with the temperature rising from room temperature to 950℃ at a heating rate of 10℃ / min, and then rapidly cooled by a fan and cooled to room temperature for 3-5min; 500g of the cooled sample was taken, 500g of slag was added, and the mixture was slowly stirred in a stirring pot for two minutes, and then 400g of water (water-binder ratio of 0.40) and 5g of water reducer were added and stirred quickly for 3min to obtain a slurry, which was poured into a 40×40×40mm mold and subjected to a compressive performance test after standard curing for 28d, recorded as F5.

[0039] Example 6 A method for activating all components of waste concrete, comprising the following steps: Select waste concrete, crush and grind it into powder with a particle size of ≤150μm, use a drum calcining furnace to heat the temperature from room temperature to 900℃ at a heating rate of 10℃ / min, then use a fan to cool it down to room temperature in 3~5min, and observe the surface morphology of the powder under a magnification of 20000 times. Figure 2 shown.

[0040] Comparative Example 1 A method for preparing recycled concrete comprises the following steps: Select waste concrete, crush and grind it into powder with a particle size of ≤150μm, take 500g sample, add 500g slag, stir slowly for two minutes in a mixing pot to mix, then add 400g water (water-cement ratio is 0.40) and 5g water reducer and stir quickly for 3min to obtain slurry, which is poured into a 40×40×40mm mold and subjected to a compressive strength test after standard curing for 28d. The slurry is recorded as F6.

[0041] Comparative Example 2 A method for preparing recycled concrete comprises the following steps: Select waste concrete, crush it and grind it into powder with a particle size of ≤150μm, take 250g sample, add 500g (PO425) cement and 250g slag, stir slowly for two minutes in a mixing pot to mix, then add 400g water (water-cement ratio is 0.40) and 5g water reducer and stir quickly for 3min to obtain slurry, which is poured into a 40×40×40mm mold. After standard curing for 28d, the compressive strength test is carried out and recorded as F7.

[0042] Comparative Example 3 A method for preparing recycled concrete comprises the following steps: Select waste concrete, crush it and grind it into powder with a particle size of ≤150μm, take 700g sample, add 300g slag, stir slowly for two minutes in a mixing pot to mix, then add 400g water (water-cement ratio is 0.40) and 5g water reducer and stir quickly for 3min to obtain slurry, which is poured into a 40×40×40mm mold and subjected to a compressive strength test after standard curing for 28d, recorded as F8.

[0043] Comparative Example 4 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected, and after preliminary crushing, it was sorted to remove large aggregates such as sand and gravel. The remaining cement stone components were then ball-milled, and powder with a particle size of ≤150μm was screened out as recycled micropowder. 500g of recycled micropowder was added with 500g of slag, and the mixture was slowly stirred in a stirring pot for two minutes. After that, 400g of water (water-cement ratio of 0.40) and 5g of water reducer were added and stirred quickly for 3min to obtain a slurry, which was poured into a 40×40×40mm mold. After standard curing for 28d, the compressive strength test was carried out and recorded as F9.

[0044] Comparative Example 5 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected, and after preliminary crushing, it was sorted to remove large aggregates such as sand and gravel. The remaining cement stone components were then ball-milled, and powder with a particle size of ≤150μm was screened out as recycled micropowder. 250g of recycled micropowder was selected, 500g (PO425) cement and 250g of slag were added, and the mixture was slowly stirred in a mixing pot for two minutes, then 400g of water (water-cement ratio of 0.40) and 5g of water reducer were added and stirred quickly for 3min to obtain a slurry, which was poured into a 40×40×40mm mold. After standard curing for 28d, the compressive strength test was carried out and recorded as F10.

[0045] Comparative Example 6 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected and crushed into powder with a particle size of ≤150μm. The temperature was raised from room temperature to 900℃ at a heating rate of 10℃ / min in a drum calciner, kept at this temperature for 20min, and then rapidly cooled by a fan. It took 500g of the cooled sample and added 500g of slag. The mixture was stirred slowly for two minutes in a stirring pot, and then 400g of water (water-binder ratio was 0.40) and 5g of water reducer were added and stirred quickly for 3min to obtain a slurry. The slurry was poured into a 40×40×40mm mold and subjected to a compressive performance test after standard curing for 28d. The slurry was recorded as F11.

[0046] Comparative Example 7 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected and crushed into powder with a particle size of ≤150μm. The temperature was raised from room temperature to 1000℃ at a heating rate of 10℃ / min in a drum calciner, and then rapidly cooled by a fan and cooled to room temperature for 3-5min. 500g of the cooled sample was taken, 500g of slag was added, and the mixture was slowly stirred in a stirring pot for two minutes. After that, 400g of water (water-binder ratio was 0.40) and 5g of water reducer were added and stirred quickly for 3min to obtain a slurry, which was poured into a 40×40×40mm mold. After standard curing for 28d, the compressive strength test was carried out and recorded as F12.

[0047] Comparative Example 8 A method for preparing recycled concrete comprises the following steps: Waste concrete was selected and crushed into powder with a particle size of ≤150μm. The temperature was raised from room temperature to 900℃ in a drum calcining furnace at a heating rate of 10℃ / min, and the mixture was cooled to room temperature for about 5h. 500g of the cooled sample was taken, 500g of slag was added, and the mixture was slowly stirred in a stirring pot for two minutes. After that, 400g of water (water-binder ratio of 0.40) and 5g of water reducer were added and stirred quickly for 3min to obtain a slurry, which was poured into a 40×40×40mm mold. After standard curing for 28d, the compressive strength test was carried out and recorded as F13.

[0048] Comparative Example 9 A method for activating all components of waste concrete, comprising the following steps: Select waste concrete, crush and grind it into powder with a particle size of ≤150μm, use a drum calcining furnace to heat the temperature from room temperature to 700℃ at a rate of 10℃ / min, then cool it down to room temperature in 3~5min by fan, and observe the surface morphology of the powder under a magnification of 20000 times. Figure 3 shown.

[0049] Comparative Example 10 A method for activating all components of waste concrete, comprising the following steps: Select waste concrete, crush and grind it into powder with a particle size of ≤150μm, use a drum calcining furnace to heat the temperature from room temperature to 1000℃ at a heating rate of 10℃ / min, then use a fan to cool it down to room temperature in 3~5min, and observe the surface morphology of the powder under a magnification of 20000 times. Figure 4 shown.

[0050] Comparative Example 11 A method for activating all components of waste concrete, comprising the following steps: Waste concrete was selected, crushed and ground into powder with a particle size of ≤150μm. The temperature was raised from room temperature to 900℃ in a drum calcining furnace at a heating rate of 10℃ / min, and then cooled to room temperature for about 5h. The surface morphology of the powder was observed at a magnification of 20,000 times. Figure 5 shown.

[0051] See also Figure 1 , Figure 1 The 28d compressive strength diagram of recycled concrete test blocks F1-F13 obtained from Examples 1-5 and Comparative Examples 1-8 of the present invention. Figure 1 It can be seen that compared with the control group of F6-F8 without activation treatment, F1-F5 has a significant improvement in compressive strength. This is due to the fact that after the surface activation of calcium carbonate, gel and other components in the waste concrete, the free calcium oxide, high-activity silica gel and other products produced have significant gelling activity. At the same time, a large amount of reaction products such as gel and calcium aluminate fill the pores, optimize the reaction interface, and ultimately promote the strength development of high-surface-active recycled concrete. Then, compared with the F9 and F10 groups using recycled micropowder, the F1 and F2 groups have higher mechanical properties. This is because the regenerated activated powder after activation treatment can effectively stimulate the slag, promote the volcanic ash reaction, and promote strength development. Finally, for the F11-F13 groups, compared with the F1 treatment method, F11 increased the holding time at 900 °C, F12 increased the calcination temperature to 1000 °C, and F13 adopted the method of furnace cooling at 900 °C. The strength of the three groups decreased significantly. This is because, under the three methods, the calcination time for the carbonate component to reach the decomposition temperature (above 700 °C) becomes longer, which will lead to an increase in the degree of calcination, and the nanoparticles originally formed on the surface will agglomerate, which will cause their size to increase and their activity to decrease.

[0052] See also Figure 2-5 , Figure 2-5 The surface morphologies of the regenerated activated powder obtained after treating all components of the waste concrete at different temperatures or different cooling methods in Example 6 and Comparative Examples 9-11 are shown respectively. Figure 2 It can be seen that under the system of Example 6, there are a large number of active calcium oxide and magnesium oxide particles of about 50 nm on the surface of the sample; Figure 3 It can be seen that when the temperature is lowered, the surface does not change because no reaction occurs; Figure 4 and 5 It can be seen that when the treatment temperature is increased or rapid cooling is not used, the nanoparticles tend to aggregate and the particle size becomes larger, resulting in a decrease in activity.

[0053] In summary, compared with the prior art, the beneficial effects of the present invention include: (1) The present invention uses surface activation treatment technology to activate the surface of calcium carbonate, gel and other components in waste concrete. The resulting products such as free calcium oxide and highly active silica gel have significant gelling activity. At the same time, a large amount of reaction products such as gel and calcium aluminate fill the pores, optimize the reaction interface, and ultimately promote the strength development of recycled concrete.

[0054] (2) The present invention significantly improves the activity of the regenerated activated powder and the interface bonding with new mineral admixtures and cement paste by surface activation modification of all components of the waste concrete.

[0055] (3) The present invention simplifies the traditional waste concrete treatment process by adopting a full-component crushing and screening treatment method. This technology is expected to promote the high-value utilization of waste concrete and provide new ideas and methods for the resource utilization of construction waste.

[0056] (4) The recycled waste concrete prepared by the present invention can be applied to various cement concrete fields such as buildings, roads, bridges, etc.

[0057] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

[0058] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for activating all components of waste concrete, characterized in that: The following steps are involved: Crushing and grinding all components of waste concrete to obtain pre-treated powder; The pretreated powder is subjected to low-temperature activation treatment and then cooled to obtain regenerated activated powder.

2. The method for activating all components of waste concrete according to claim 1, characterized in that: The particle size of the pretreated powder is ≤150 μm.

3. The method for activating all components of waste concrete according to claim 1, characterized in that: The low-temperature activation treatment is carried out by calcining the pretreated powder at a heating rate of 5-20°C / min, a calcination temperature of 750-950°C, and a calcination time of 0-10min.

4. The method for activating all components of waste concrete according to claim 1, characterized in that: Rapid cooling is adopted, and the process of the rapid cooling is: cooling to room temperature in 3-5 minutes.

5. A regenerated activated powder, characterized in that: The regenerated activated powder is obtained by the activation treatment method of all components of waste concrete as described in any one of claims 1-4.

6. An application of regenerated activated powder, characterized in that: The regenerated activated powder as claimed in claim 5 is used as a cementitious component in recycled concrete.

7. The use of the regenerated activated powder according to claim 6, characterized in that: The raw materials of the recycled concrete also include: cement and / or mineral admixtures; wherein, The regenerated activated powder accounts for 0.1-100% of the total mass of the regenerated activated powder, cement and mineral admixtures; The cement accounts for 0-99.9% of the total mass of the regenerated activated powder, cement and mineral admixtures; The mineral admixture accounts for 0-99.9% of the total mass of the regenerated activated powder, cement and the mineral admixture.

8. The use of the regenerated activated powder according to claim 6, characterized in that: The raw materials of the recycled concrete also include: aggregate; wherein, The aggregate accounts for 0-70% of the total mass of the regenerated activated powder, cement and mineral admixtures.

9. The use of the regenerated activated powder according to claim 6, characterized in that: The raw materials of the recycled concrete also include: water reducing agent; wherein, The water reducer is a polycarboxylate water reducer; and / or, The solid content of the water reducing agent is 30%-50%; and / or, The water reducing agent accounts for 0.1%-5% of the total mass of the regenerated activated powder, cement and mineral admixtures.

10. The use of the regenerated activated powder according to claim 6, characterized in that: The raw materials of the recycled concrete also include: water; wherein, The water accounts for 30%-50% of the total mass of the regenerated activated powder, cement and mineral admixtures.

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