Recycled concrete aggregate reinforced by construction waste micro powder and preparation method thereof
阅读说明：本技术 一种利用建筑垃圾微粉强化的再生混凝土骨料及制备方法 (Recycled concrete aggregate reinforced by construction waste micro powder and preparation method thereof ) 是由 赵计辉 李忠 丁晓平 王葆霞 丁继鹏 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种利用建筑垃圾微粉强化的再生混凝土骨料,所述再生混凝土骨料由基体、改性包裹层与表面强化层组成,所述基体为回收骨料,所述改性包裹层为强化浆液,所述表面强化层为碳化物；其中,质量份数为：所述回收骨料占80％-95％,所述强化浆液占4％-15％,所述碳化物占1％-5％。本发明还提供了所述再生混凝土骨料的制备方法。本发明方法原料易得,最大程度地利用了废弃混凝土骨料及其微粉,利废环保、成本低、工艺流程简单,便于应用工程实际,制备的改性再生混凝土骨料物理力学性能优异,应用前景广阔。(The invention discloses a recycled concrete aggregate reinforced by construction waste micro powder, which consists of a substrate, a modified coating layer and a surface reinforcing layer, wherein the substrate is a recycled aggregate, the modified coating layer is reinforcing slurry, and the surface reinforcing layer is carbide; wherein the mass portions are as follows: the recycled aggregate accounts for 80-95%, the reinforced slurry accounts for 4-15%, and the carbide accounts for 1-5%. The invention also provides a preparation method of the recycled concrete aggregate. The method has the advantages of easily available raw materials, maximum utilization of the waste concrete aggregate and the micro powder thereof, waste utilization, environmental protection, low cost, simple process flow and convenient application of engineering practice, and the prepared modified recycled concrete aggregate has excellent physical and mechanical properties and wide application prospect.)
1. The recycled concrete aggregate reinforced by the construction waste micro powder is composed of a base body, a modified wrapping layer and a surface reinforcing layer, and is characterized in that the base body is recycled aggregate, the modified wrapping layer is reinforcing slurry, and the surface reinforcing layer is carbide; wherein the mass portions are as follows: the recycled aggregate accounts for 80-95%, the reinforced slurry accounts for 4-15%, and the carbide accounts for 1-5%.
2. The recycled concrete aggregate reinforced by the construction waste micropowder according to claim 1, wherein the recycled aggregate is a waste concrete aggregate containing a binding mortar, and the reinforcing grout is composed of construction waste micropowder, cement, a water reducing agent and water; the carbide consists of one or more of the products of intensified slurry carbonization, calcite, vaterite, and aragonite.
3. A method for preparing the recycled concrete aggregate reinforced with construction waste micropowder according to claim 1, characterized by comprising the steps of:
s1, stirring the recycled aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled aggregate, taking out, and screening out the dust and impurities to obtain the spare recycled concrete aggregate;
s2, uniformly stirring the construction waste micro powder, the cement, the water reducing agent and the water according to a certain proportion to prepare the reinforced slurry with the water-cement ratio of 0.35 and the bone-paste ratio of 0.5;
s3, putting the recycled concrete aggregate pretreated in the step S1 into the reinforced slurry prepared in the step S2, uniformly stirring in a horizontal stirrer, taking out the slurry, draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer on the surface of the recycled concrete aggregate;
s4, placing the recycled concrete aggregate wrapped by the reinforced slurry obtained in the step S3 into a carbonization box for maintenance, taking out the recycled concrete aggregate after the maintenance age is reached, naturally drying the recycled concrete aggregate, and forming a compact carbide reinforced layer on the basis of the recycled concrete aggregate reinforced slurry wrapping layer, so that the recycled concrete aggregate reinforced by the building waste micro powder is obtained.
4. The method for preparing recycled concrete aggregate reinforced with construction waste micropowder according to claim 3, wherein the recycled aggregate stirred in step S1 has a particle size of 4.75 to 9.5mm and a class III grade.
5. The method for preparing recycled concrete aggregate reinforced by construction waste micropowder according to claim 3, wherein the construction waste micropowder has a particle size of less than 0.16mm and an average particle size of 15 to 25 μm in an amount of 10 to 30% by mass of the cementitious material in step S2.
6. The method for preparing recycled concrete aggregate reinforced by construction waste micropowder according to claim 3, wherein the cement in step S2 is Portland cement of 42.5MPa grade, and the amount of the cement is 70-90% of the cementitious material.
7. The method for preparing recycled concrete aggregate reinforced by construction waste micropowder according to claim 3, wherein the water reducing agent in step S2 is a polycarboxylic acid high efficiency water reducing agent with 40% of liquid solid content, the water reducing rate is not less than 25%, and the mixing amount is 0.2-0.5% of the total mass of the cementitious material.
8. The method for preparing recycled concrete aggregate reinforced by using construction waste micropowder according to claim 3, wherein the control conditions of the carbonization chamber in the step S4 are that the humidity is 60-90%, the temperature is 20 ℃ ± 2 ℃, the carbon dioxide concentration is 20-40%, and the pressure is 0.1-0.5 MPa; the curing age is 7-28 days.
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to recycled concrete aggregate reinforced by building waste micro powder and a preparation method thereof.
Background
With the acceleration of the urbanization construction process of China, the quantity of the construction waste in China can reach 20 hundred million tons every year, the annual average speed is increased by 10 percent, and the quantity of the construction waste in China accounts for 30 to 40 percent of the total quantity of the urban waste. The site selection of the construction waste stacking site is random to a great extent and is difficult to degrade, and the problems of dust and the like generated in the process of clearing and stacking the construction waste cause environmental pollution. At present, the comprehensive utilization rate of construction waste resources in China is less than 10%, the comprehensive utilization rate is mainly focused on the aspect of recycled concrete aggregate, while the construction waste micro powder is a problem which is not negligible when waste concrete is recycled and accounts for about 5% -20% of the total amount of the waste concrete, the main mineral components of the construction waste micro powder are silicon dioxide, calcium hydroxide, ettringite, calcium aluminosilicate and other components which have potential activation characteristics, and a large amount of carbon dioxide waste gas is generated in the production of the cement industry.
The recycled concrete aggregate is adhered with a layer of old mortar, and the structure damage is inevitably generated in the recycling process and other processes, so that the recycled concrete aggregate has micro cracks, the strength, the apparent density and the bulk density of the recycled concrete aggregate are lower than those of the natural aggregate, and the water absorption rate are much higher than those of the natural aggregate. Due to the factors, the application effect of the recycled aggregate in concrete is not ideal, and the utilization rate of building material resource is limited.
How to effectively improve the performance of recycled concrete aggregate, break through the resource recycling of construction waste micropowder, realize economic and environmental benefits, and is an industry problem which is urgently needed to be dealt with in the current industry construction resource utilization process.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a recycled concrete aggregate reinforced by using construction waste micro powder and a preparation method thereof. The method realizes that the performance of the recycled concrete aggregate can be effectively improved, the utilization rate of the construction waste micro powder can be improved, and a new way for consuming carbon dioxide is provided.
In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:
a recycled concrete aggregate reinforced by construction waste micro powder is composed of a substrate, a modified coating layer and a surface reinforcing layer, wherein the substrate is a recycled aggregate, the modified coating layer is reinforcing slurry, and the surface reinforcing layer is carbide; wherein the mass portions are as follows: the recycled aggregate accounts for 80-95%, the reinforced slurry accounts for 4-15%, and the carbide accounts for 1-5%.
The recycled aggregate is waste concrete aggregate containing bonding mortar, and the reinforced slurry consists of construction waste recycled micro powder, cement, a water reducing agent and water; the carbide consists of one or more of the products of intensified slurry carbonization, calcite, vaterite, and aragonite.
The invention also provides a preparation method of the recycled concrete aggregate reinforced by the construction waste micro powder, which comprises the following steps:
s1, stirring the recycled aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled aggregate, taking out, and screening out the dust and impurities to obtain the spare recycled concrete aggregate;
s2, uniformly stirring the construction waste micro powder, the cement, the water reducing agent and the water according to a certain proportion to prepare the reinforced slurry with the water-cement ratio of 0.35 and the bone-paste ratio of 0.5;
s3, putting the recycled concrete aggregate pretreated in the step S1 into the reinforced slurry prepared in the step S2, uniformly stirring in a horizontal stirrer, taking out the slurry, draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer on the surface of the recycled concrete aggregate;
s4, placing the recycled concrete aggregate wrapped by the reinforced slurry obtained in the step S3 into a carbonization box for maintenance, taking out the recycled concrete aggregate after the maintenance age is reached, naturally drying the recycled concrete aggregate, and forming a compact carbide reinforced layer on the basis of the recycled concrete aggregate reinforced slurry wrapping layer, so that the recycled concrete aggregate reinforced by the building waste micro powder is obtained.
In step S1, the recycled aggregate is classified into class III aggregate having a particle size of 4.75 to 9.5 mm.
In step S2, the particle size of the construction waste micropowder is less than 0.16mm, the average particle size is 15-25 μm, and the usage amount is 10-30% of the mass of the binding material.
It should be noted that, in step S2, the cement is 42.5Mpa portland cement, and the amount of the cement is 70-90% of the cement.
It is noted that the water reducing agent in step S2 is a polycarboxylic acid high-efficiency water reducing agent with a liquid solid content of 40%, the water reducing rate is not less than 25%, and the blending amount is 0.2-0.5% of the total mass of the cementitious material.
In step S4, the carbonization chamber is controlled under the conditions of humidity 60-90%, temperature 20 ℃ ± 2 ℃, carbon dioxide concentration 20-40%, and pressure 0.1-0.5 Mpa; the curing age is 7-28 days.
The invention has the beneficial effects that:
1. the invention not only effectively improves the performance of recycled concrete aggregate, but also greatly utilizes the construction waste micro powder and consumes a large amount of carbon dioxide, is an efficient green and low-carbon technology, and belongs to a new technical path of carbon peak reaching and carbon neutralization.
2. The invention relates to a recycled concrete aggregate reinforced by construction waste micropowder, the consumption of the construction waste micropowder reaches 10 to 30 percent, the raw materials are mainly derived from byproducts in the processes of construction waste recovery, recycled concrete aggregate production and the like, and on one hand, the recycling utilization (especially high value-added utilization) of the recycled concrete aggregate in China and other industrial byproducts of construction waste can be effectively promoted; on the other hand, the construction waste micro powder and the recycled concrete aggregate have wide sources (almost every province of China has a large amount of urban construction waste), most of the construction waste micro powder and the recycled concrete aggregate can be obtained from local materials and are convenient to process; in the third aspect, the construction waste micropowder is mainly utilized, so the cost is extremely low, and the production can be widely distributed, so the method is favorable for promoting the difficulty of urban construction waste treatment and can be popularized and used in a large range.
3. On one hand, the reinforced slurry wrapping layer takes the calcium silicate hydrate gel as a main reinforcing phase to fill micro cracks and pores of the recycled concrete aggregate, and bonds and reinforces the weak interface transition area of the recycled concrete aggregate and the surface of the recycled concrete aggregate to form a compact structure and a surface compact layer with equivalent aggregate strength; on the other hand, through the modification of the reinforced slurry coating layer, the water absorption rate and the crushing value of the recycled concrete aggregate are both obviously reduced, and the defects of high porosity, loose surface and poor mechanical property of the recycled concrete aggregate are effectively overcome.
4. The carbide strengthening layer of the invention forms a compact strengthening layer interweaved by calcite, vaterite, aragonite and calcium silicate hydrate on the basis of strengthening the slurry wrapping layer, further improves the mechanical property of the recycled concrete aggregate, and obviously reduces the surface porosity, the water absorption rate and the crushing value.
5. The reinforced recycled concrete aggregate is composed of a recycled aggregate matrix, a reinforced slurry coating layer and a carbide reinforcing layer in a multi-stage cooperative structure, wherein the recycled aggregate matrix plays a role of a framework, the coating layer plays a role of structure reinforcement, and the carbide layer plays a role of surface reinforcement to form a multi-stage compact structure which is interlaced from inside to outside and has different mineral phases.
Detailed Description
The present invention will be further described below, and it should be noted that the present embodiment is based on the technical solution, and a detailed implementation manner and a specific operation process are provided, but the protection scope of the present invention is not limited to the present embodiment.
It should be noted that the recycled concrete aggregates used in the examples and comparative examples of the present invention are single-grain recycled concrete aggregates having a grain size of 4.75 to 9.5 mm;the cement is 42.5-grade ordinary portland cement with the density of 3200kg/m3(ii) a The particle size of the construction waste micro powder is less than 0.16mm after screening; the water reducing rate of the polycarboxylic acid high-efficiency water reducing agent is 37 percent, and the solid content of the liquid is 40 percent; example water is tap water.
The invention relates to recycled concrete aggregate reinforced by construction waste micro powder, which consists of a substrate, a modified wrapping layer and a surface reinforcing layer, wherein the substrate is recycled aggregate, the modified wrapping layer is reinforcing slurry, and the surface reinforcing layer is made of carbide; wherein the mass portions are as follows: the recycled aggregate accounts for 80-95%, the reinforced slurry accounts for 4-15%, and the carbide accounts for 1-5%.
The recycled aggregate is waste concrete aggregate containing bonding mortar, and the reinforced slurry consists of construction waste recycled micro powder, cement, a water reducing agent and water; the carbide consists of one or more of the products of intensified slurry carbonization, calcite, vaterite, and aragonite.
The invention also provides a preparation method of the recycled concrete aggregate reinforced by the construction waste micro powder, which comprises the following steps:
s1, stirring the recycled aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled aggregate, taking out, and screening out the dust and impurities to obtain the spare recycled concrete aggregate;
s2, uniformly stirring the construction waste micro powder, the cement, the water reducing agent and the water according to a certain proportion to prepare the reinforced slurry with the water-cement ratio of 0.35 and the bone-paste ratio of 0.5;
s3, putting the recycled concrete aggregate pretreated in the step S1 into the reinforced slurry prepared in the step S2, uniformly stirring in a horizontal stirrer, taking out the slurry, draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer on the surface of the recycled concrete aggregate;
s4, placing the recycled concrete aggregate wrapped by the reinforced slurry obtained in the step S3 into a carbonization box for maintenance, taking out the recycled concrete aggregate after the maintenance age is reached, naturally drying the recycled concrete aggregate, and forming a compact carbide reinforced layer on the basis of the recycled concrete aggregate reinforced slurry wrapping layer, so that the recycled concrete aggregate reinforced by the building waste micro powder is obtained.
In step S1, the recycled aggregate is classified into class III aggregate having a particle size of 4.75 to 9.5 mm.
In step S2, the particle size of the construction waste micropowder is less than 0.16mm, the average particle size is 15-25 μm, and the usage amount is 10-30% of the mass of the binding material.
It should be noted that, in step S2, the cement is 42.5Mpa portland cement, and the amount of the cement is 70-90% of the cement.
It is noted that the water reducing agent in step S2 is a polycarboxylic acid high-efficiency water reducing agent with a liquid solid content of 40%, the water reducing rate is not less than 25%, and the blending amount is 0.2-0.5% of the total mass of the cementitious material.
In step S4, the carbonization chamber is controlled under the conditions of humidity 60-90%, temperature 20 ℃ ± 2 ℃, carbon dioxide concentration 20-40%, and pressure 0.1-0.5 Mpa; the curing age is 7-28 days.
The excellent properties of the present invention will be further demonstrated by comparative tests.
Comparative example 1
This comparative example comprises the following steps:
(1) stirring raw materials of the recycled concrete aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled concrete aggregate, taking out, and screening out the dust and the impurities to obtain the spare recycled concrete aggregate;
(2) 5.037kg of cement and 18g of water reducing agent are added into 1.763kg of water and stirred uniformly to prepare reinforced slurry;
(3) pouring 13.6kg of standby recycled concrete aggregate into the reinforced slurry, uniformly stirring in a horizontal stirrer, taking out and draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer on the surface of the recycled concrete aggregate;
(4) and (3) putting the recycled concrete aggregate wrapped by the reinforced slurry into a standard curing room (the control conditions are that the humidity is more than 95 percent and the temperature is 20 +/-2 ℃) for curing, taking out the recycled concrete aggregate after the curing period reaches 14 days, and naturally drying the recycled concrete aggregate to prepare the recycled concrete aggregate reinforced by the cement slurry.
Comparative example 2
This comparative example comprises the following steps:
(1) stirring raw materials of the recycled concrete aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled concrete aggregate, taking out, and screening out the dust and the impurities to obtain the spare recycled concrete aggregate;
(2) 5.037kg of cement and 18g of water reducing agent are added into 1.763kg of water and stirred uniformly to prepare reinforced slurry;
(3) pouring 13.6kg of standby recycled concrete aggregate into the reinforced slurry, uniformly stirring in a horizontal stirrer, taking out and draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer on the surface of the recycled concrete aggregate;
(4) and (2) putting the recycled concrete aggregate wrapped by the reinforced slurry into a carbonization box (under the control conditions that the humidity is 70%, the temperature is 20 ℃, the carbon dioxide concentration is 20% and the pressure is 0.1Mpa), curing, taking out the recycled concrete aggregate after the curing age reaches 14 days, naturally drying the recycled concrete aggregate, and forming a compact carbide reinforced layer on the basis of the recycled concrete aggregate reinforced slurry wrapping layer, thereby preparing the recycled concrete aggregate reinforced by the cement slurry.
Comparative example 3
The embodiment comprises the following steps:
(1) stirring raw materials of the recycled concrete aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled concrete aggregate, taking out, and screening out the dust and the impurities to obtain the spare recycled concrete aggregate;
(2) 5.037kg of cementing material (0.504 kg of construction waste micro powder and 4.533kg of cement) and 18g of water reducing agent are added into 1.763kg of water and stirred evenly to prepare reinforced slurry;
(3) putting 13.6kg of standby recycled concrete aggregate into the reinforced slurry, uniformly stirring in a stirrer, taking out and draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer on the surface of the recycled concrete aggregate;
(4) and (3) putting the recycled concrete aggregate wrapped by the reinforced slurry into a standard curing room (the control conditions are that the humidity is more than 95% and the temperature is 20 +/-2 ℃) for curing, taking out the recycled concrete aggregate after the curing period reaches 14 days, and naturally drying the recycled concrete aggregate to prepare the recycled concrete aggregate reinforced by the construction waste micro-powder slurry.
Comparative example 4
The embodiment comprises the following steps:
(1) stirring raw materials of the recycled concrete aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled concrete aggregate, taking out, and screening out the dust and the impurities to obtain the spare recycled concrete aggregate;
(2) 5.037kg of cementing material (1.007 kg of construction waste micro powder and 4.03kg of cement) and 18g of water reducing agent are added into 1.763kg of water and stirred uniformly to prepare reinforced slurry;
(3) putting 13.6kg of standby recycled concrete aggregate into the reinforced slurry, uniformly stirring in a stirrer, taking out and draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer on the surface of the recycled concrete aggregate;
(4) and (3) putting the recycled concrete aggregate wrapped by the reinforced slurry into a standard curing room (the control conditions are that the humidity is more than 95% and the temperature is 20 +/-2 ℃) for curing, taking out the recycled concrete aggregate after the curing period reaches 14 days, and naturally drying the recycled concrete aggregate to prepare the recycled concrete aggregate reinforced by the construction waste micro-powder slurry.
Comparative example 5
The embodiment comprises the following steps:
(1) stirring raw materials of the recycled concrete aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled concrete aggregate, taking out, and screening out the dust and the impurities to obtain the spare recycled concrete aggregate;
(2) 5.037kg of cementing material (1.511 kg of construction waste micro powder and 3.526kg of cement) and 18g of water reducing agent are added into 1.763kg of water and stirred uniformly to prepare reinforced slurry;
(3) putting 13.6kg of standby recycled concrete aggregate into the reinforced slurry, uniformly stirring in a stirrer, taking out and draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer on the surface of the recycled concrete aggregate;
(4) and (3) putting the recycled concrete aggregate wrapped by the reinforced slurry into a standard curing room (the control conditions are that the humidity is more than 95% and the temperature is 20 +/-2 ℃) for curing, taking out the recycled concrete aggregate after the curing period reaches 14 days, and naturally drying the recycled concrete aggregate to prepare the recycled concrete aggregate reinforced by the construction waste micro-powder slurry.
Comparative example 6
This comparative example was made in order to investigate the effect of carbonization alone on recycled concrete aggregate, and it included the following steps:
(1) cleaning raw materials of the recycled concrete aggregate with water, putting the cleaned raw materials into a carbonization box (under the control conditions that the humidity is 70%, the temperature is 20 ℃, the carbon dioxide concentration is 20% and the pressure is 0.1Mpa), curing for 24 hours, taking out the cured raw materials, and naturally drying the cured raw materials to prepare the carbonized recycled concrete aggregate.
The crushing value test before and after the carbonization of the recycled concrete aggregate is carried out according to the test method of the standard GB/T24685-2011 construction pebbles and macadam. According to the implementation results, the crushing value of the recycled concrete aggregate after only carbonization is not improved, and is even slightly increased. This is because the recycled concrete aggregate has a low content of carbonizable substances, and the carbonization has a low effect on modifying the recycled concrete aggregate, which is limited to a large extent.
Example 1
The embodiment comprises the following steps:
(1) stirring raw materials of the recycled concrete aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled concrete aggregate, taking out, and screening out the dust and the impurities to obtain the spare recycled concrete aggregate;
(2) 5.037kg of cementing material (0.504 kg of construction waste micro powder and 4.533kg of cement) and 18g of water reducing agent are added into 1.763kg of water and stirred evenly to prepare reinforced slurry;
(3) putting 13.6kg of standby recycled concrete aggregate into the reinforced slurry, uniformly stirring in a stirrer, taking out and draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer (the mass fraction is about 5%) on the surface of the recycled concrete aggregate;
(4) and (2) putting the recycled concrete aggregate wrapped by the reinforced slurry into a carbonization box (under the control conditions that the humidity is 70%, the temperature is 20 ℃, the carbon dioxide concentration is 20% and the pressure is 0.1Mpa), curing for 14 days, taking out the recycled concrete aggregate and naturally drying the recycled concrete aggregate after the curing age is reached, and forming a compact carbide reinforced layer (the mass fraction is about 3.5%) on the basis of the recycled concrete aggregate reinforced slurry wrapping layer, thereby preparing the recycled concrete aggregate reinforced by the construction waste micro powder.
Example 2
The embodiment comprises the following steps:
(1) stirring raw materials of the recycled concrete aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled concrete aggregate, taking out, and screening out the dust and the impurities to obtain the spare recycled concrete aggregate;
(2) 5.037kg of cementing material (1.007 kg of construction waste micro powder and 4.03kg of cement) and 18g of water reducing agent are added into 1.763kg of water and stirred uniformly to prepare reinforced slurry;
(3) putting 13.6kg of standby recycled concrete aggregate into the reinforced slurry, uniformly stirring in a stirrer, taking out and draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer (the mass fraction is about 6%) on the surface of the recycled concrete aggregate;
(4) and (2) putting the recycled concrete aggregate wrapped by the reinforced slurry into a carbonization box (under the control conditions that the humidity is 70%, the temperature is 20 ℃, the carbon dioxide concentration is 20% and the pressure is 0.1Mpa), curing, taking out the recycled concrete aggregate after the curing age reaches 14 days, naturally drying the recycled concrete aggregate, and forming a compact carbide reinforced layer (the mass fraction is about 4%) on the basis of the recycled concrete aggregate reinforced slurry wrapping layer, thereby preparing the recycled concrete aggregate reinforced by the construction waste micro powder.
Example 3
The embodiment comprises the following steps:
(1) stirring raw materials of the recycled concrete aggregate in a horizontal mixer, removing loose mortar particles and part of dust impurities on the surface of the recycled concrete aggregate, taking out, and screening out the dust and the impurities to obtain the spare recycled concrete aggregate;
(2) 5.037kg of cementing material (1.511 kg of construction waste micro powder and 3.526kg of cement) and 18g of water reducing agent are added into 1.763kg of water and stirred uniformly to prepare reinforced slurry;
(3) putting 13.6kg of standby recycled concrete aggregate into the reinforced slurry, uniformly stirring in a stirrer, taking out and draining the slurry, naturally air-drying the surface of the aggregate, and preparing a reinforced slurry coating layer (the mass fraction is about 4.5%) on the surface of the recycled concrete aggregate;
(4) and (2) putting the recycled concrete aggregate wrapped by the reinforced slurry into a carbonization box (under the control conditions that the humidity is 70%, the temperature is 20 ℃, the carbon dioxide concentration is 20% and the pressure is 0.1Mpa), curing for 14 days, taking out the recycled concrete aggregate after the curing age is reached, naturally drying the recycled concrete aggregate, and forming a compact carbide reinforced layer (the mass fraction is about 3%) on the basis of the recycled concrete aggregate reinforced slurry wrapping layer, thereby preparing the recycled concrete aggregate reinforced by the construction waste micro powder.
According to the test method of the GB/T24685-2011 construction pebbles and gravels and the standard of the CJJT 253 and 2016 recycled concrete aggregate permeable concrete application technical specification, performance comparison evaluation before and after modification of the recycled concrete aggregate is carried out, and the following tables show that:
performance of
Crush value index (%)
Apparent density (kg-m3 )
Bulk density (kg-m3 )
Water absorption (%)
Raw materials
26.81
2409
1303
3.12
Comparative example 1
17
2465
1351
3.91
Comparative example 2
15.85
2509
1412
3.30
Comparative example 3
16.46
2479
1362
3.96
Comparative example 4
16.17
2503
1383
3.72
Comparative example 5
16.22
2472
1349
4.06
Example 1
15.36
2511
1422
3.7
Example 2
14.78
2543
1427
3.47
Example 3
15.93
2499
1410
3.72
As can be seen from the data in the table above in combination with the standards, the recycled concrete aggregate before treatment does not meet the standard of II-class aggregate, and the apparent density and the bulk density of the recycled concrete aggregate after treatment of the comparative example and the embodiment are obviously increased, and both meet the standard of II-class aggregate. However, the recycled concrete aggregate treated by the comparative example has the common increase amplitude of the water absorption rate of 19.2 to 30.12 percent and the common decrease amplitude of the crushing value of 36.6 to 40.9 percent; the recycled concrete aggregate treated in the example has the common increase amplitude of water absorption of 11.22-19.23% and the common decrease amplitude of crushing value of 40.58-44.87%.
The comparison of comparative example 1 (only cement reinforced slurry coating) with examples 1-3 (construction waste micropowder reinforced slurry coating + carbide reinforced coating) shows that comparative example 1 has inferior gain effect on recycled aggregate to example 2 and higher cost.
By comparing comparative example 2 (slurry-reinforced coating layer + carbide-reinforced layer only with cement slurry) with examples 1-2 (construction waste micropowder-reinforced slurry coating layer + carbide-reinforced layer), it was found that comparative example 2 is inferior in the gain effect (crushing value, apparent density, bulk density) to recycled aggregate as compared with examples 1-3 and is higher in cost.
As shown by comparing comparative examples 3-5 (reinforcing the slurry coating layer only with the construction waste micropowder) with examples 1-3 (reinforcing the slurry coating layer with the construction waste micropowder + the carbide reinforcing layer), comparative examples 3-5 have inferior effect on the gain of the recycled aggregate to examples 1-3 and higher cost.
Through comparison between examples 1-3, as the mass fractions of the reinforcing liquid coating layer and the carbide strengthening layer on the surface of the recycled aggregate are increased, the crushing value and the water absorption rate are reduced, and the apparent density and the bulk density are increased, which is shown as that the quality and the performance of the aggregate are better.
Various corresponding modifications may be suggested to one skilled in the art based on the foregoing teachings and concepts, and all such modifications are intended to be included within the scope of the present invention as defined by the appended claims.