阅读说明：本技术 一种再生骨料混凝土及其制备方法 (Recycled aggregate concrete and preparation method thereof ) 是由 胡福华 于 2021-07-26 设计创作，主要内容包括：本申请涉及混凝土技术领域,具体公开了一种再生骨料混凝土及其制备方法,该再生骨料混凝土包括以下重量份的原料：水泥350-390份、天然砂500-600份、粉煤灰60-80份、矿粉40-70份、硅灰粉50-80份、改性再生粗骨料800-1000份、丁苯乳液60-100份、聚氨酯纤维30-80份、聚乙烯醇纤维20-50份、减水剂5-7份；水150-170份；制备方法为：将改性再生粗骨料、天然砂、水泥以及40-80重量份的水混合,混合均匀后加入粉煤灰、矿粉、硅灰粉混合均匀,后与丁苯乳液、聚氨酯纤维、聚乙烯醇纤维以及剩余的水混合均匀后,加入减水剂混合均匀得到再生骨料混凝土；该再生骨料混凝土具有强度高的优点。(The application relates to the technical field of concrete, and particularly discloses recycled aggregate concrete and a preparation method thereof, wherein the recycled aggregate concrete comprises the following raw materials in parts by weight: 390 parts of cement 350-containing material, 600 parts of natural sand 500-containing material, 60-80 parts of fly ash, 40-70 parts of mineral powder, 50-80 parts of silica fume powder, 1000 parts of modified and regenerated coarse aggregate 800-containing material, 60-100 parts of butylbenzene emulsion, 30-80 parts of polyurethane fiber, 20-50 parts of polyvinyl alcohol fiber and 5-7 parts of water reducing agent; 150 portions of water and 170 portions of water; the preparation method comprises the following steps: mixing the modified recycled coarse aggregate, the natural sand, the cement and 40-80 parts by weight of water, adding the fly ash, the mineral powder and the silica fume powder after uniformly mixing, then uniformly mixing with the butylbenzene emulsion, the polyurethane fiber, the polyvinyl alcohol fiber and the rest water, adding the water reducing agent, and uniformly mixing to obtain recycled aggregate concrete; the recycled aggregate concrete has the advantage of high strength.)

1. The recycled aggregate concrete is characterized by comprising the following raw materials in parts by weight:

cement 350-;

500 portions and 600 portions of natural sand;

60-80 parts of fly ash;

40-70 parts of mineral powder;

50-80 parts of silica fume powder;

800 portions of modified regenerated coarse aggregate and 1000 portions of modified regenerated coarse aggregate;

60-100 parts of butylbenzene emulsion;

30-80 parts of polyurethane fiber;

20-50 parts of polyvinyl alcohol fibers;

5-7 parts of a water reducing agent;

150 portions of water and 170 portions of water.

2. The recycled aggregate concrete of claim 1, wherein the modified recycled coarse aggregate comprises the following preparation steps:

a1, cleaning the recycled coarse aggregate, heating at the temperature of 340-360 ℃, and then grinding and crushing to obtain the processed recycled coarse aggregate;

a2, mixing the treated recycled coarse aggregate with polyolefin fibers, an accelerant and a silane coupling agent, and uniformly mixing to obtain the modified recycled coarse aggregate.

3. The recycled aggregate concrete according to claim 2, wherein: the weight ratio of the recycled coarse aggregate, the polyolefin fiber, the accelerator and the silane coupling agent is 1 (0.05-0.1): (0.03-0.05): 0.01-0.02).

4. The recycled aggregate concrete of claim 2, wherein the accelerator comprises at least one of a cationic rosin size and a polyamide epichlorohydrin resin.

5. The recycled aggregate concrete according to claim 2, wherein: in the step A1, the recycled coarse aggregate is ultrasonically cleaned for 3-5 times by adopting an acetic acid solution, wherein the concentration of the acetic acid solution is 0.2-0.4 mol/L.

6. The recycled aggregate concrete according to claim 1, wherein: the raw materials of the recycled aggregate concrete also comprise 11-24 parts by weight of reinforcing agent, and the reinforcing agent consists of poplar fiber and n-dodecyl mercaptan in a mass ratio of 1 (0.1-0.2).

7. The recycled aggregate concrete according to claim 1, wherein: the raw materials of the recycled aggregate concrete also comprise 10-20 parts by weight of rubber powder.

8. The method for producing recycled aggregate concrete according to any one of claims 1 to 7, wherein: the method comprises the following steps:

s1, mixing the modified recycled coarse aggregate, the natural sand, the cement and 60-80 parts by weight of water, adding the fly ash, the mineral powder and the silica fume powder after uniformly mixing, and uniformly mixing to obtain a first mixture;

and S2, uniformly mixing the first mixture with the butylbenzene emulsion, the polyurethane fiber, the polyvinyl alcohol fiber and the rest water, adding the water reducing agent, and uniformly mixing to obtain the recycled aggregate concrete.

9. The method for preparing recycled aggregate concrete according to claim 8, wherein the concrete is prepared by the following steps: in the step S2, a reinforcing agent and rubber powder are added, and the reinforcing agent and the rubber powder are added together with the butylbenzene emulsion, the polyurethane fiber, the polyvinyl alcohol fiber and the rest water.

Technical Field

The invention relates to the technical field of concrete, in particular to recycled aggregate concrete and a preparation method thereof.

Background

The recycled aggregate concrete is prepared by mechanically crushing and cleaning waste concrete to obtain test blocks, finally screening the test blocks to obtain recycled aggregate, and substituting natural aggregate with the recycled aggregate according to a certain proportion, so that resources are effectively saved, and the environment is protected.

The recycled aggregate concrete disclosed in publication No. CN101671147A, 03/2010 and 17/2010 is composed of cement, recycled coarse aggregate, recycled fine aggregate, admixture, water and pumping agent, and comprises the following components in percentage by weight: 4-20% of cement and 0-35% of recycled fine aggregate; 0-46% of regenerated coarse aggregate, 1-8% of admixture, 1.5-2.5% of concrete pumping aid based on the total weight of cement and admixture, and the balance of water; the admixture is fly ash and granulated blast furnace slag powder.

Through the related technology, as the recycled aggregate is derived from the waste concrete and a certain amount of cement mortar exists on the surface, the water absorption of the recycled aggregate is higher, and the strength of the recycled aggregate concrete is reduced.

Disclosure of Invention

In order to enhance the strength of the recycled aggregate concrete, the application provides the recycled aggregate concrete and a fermentation process thereof.

In a first aspect, the present application provides a recycled aggregate concrete, which adopts the following technical scheme:

the recycled aggregate concrete comprises the following raw materials in parts by weight:

cement 350-;

500 portions and 600 portions of natural sand;

60-80 parts of fly ash;

40-70 parts of mineral powder;

50-80 parts of silica fume powder;

800 portions of modified regenerated coarse aggregate and 1000 portions of modified regenerated coarse aggregate;

60-100 parts of butylbenzene emulsion;

30-80 parts of polyurethane fiber;

20-50 parts of polyvinyl alcohol fibers;

5-7 parts of a water reducing agent;

150 portions of water and 170 portions of water;

by adopting the technical scheme, the recycled aggregate concrete with higher strength is prepared by adding the butylbenzene emulsion, the polyurethane fiber and the polyvinyl alcohol fiber and modifying the recycled coarse aggregate. The recycled coarse aggregate is modified, so that the water absorption of the recycled coarse aggregate is reduced, and the density of the recycled coarse aggregate is improved, thereby improving the strength of the recycled coarse aggregate. The combination of polyurethane fiber with higher elasticity and strength and polyvinyl alcohol fiber with better water resistance is adopted, so that the water absorption of the recycled aggregate concrete is reduced, and the strength of the concrete is improved. Because the bonding performance of the fiber and a cement stone interface in concrete is poor, the polyurethane fiber, the polyvinyl alcohol fiber and the modified recycled coarse aggregate are effectively combined with natural sand, cement and the like in the concrete by adding the butylbenzene emulsion, so that the strength of the concrete is enhanced. In addition, the silica fume powder further enhances the strength of the recycled aggregate concrete by filling the pores in the modified recycled coarse aggregate.

In summary, the polyurethane fiber and the polyvinyl alcohol fiber are added to modify the recycled coarse aggregate, and the modified recycled coarse aggregate is matched with the butylbenzene emulsion to be effectively bonded in cement and natural sand, so that the water absorption of the concrete is reduced, and simultaneously, the pores in the concrete are filled, and the strength of the recycled aggregate concrete is enhanced.

Preferably, the modified recycled coarse aggregate comprises the following preparation steps:

a1, cleaning the recycled coarse aggregate, heating at the temperature of 340-360 ℃, and then grinding and crushing to obtain the processed recycled coarse aggregate;

a2, mixing the treated recycled coarse aggregate with polyolefin fiber, an accelerant and a silane coupling agent, and uniformly mixing to obtain the modified recycled aggregate.

By adopting the technical scheme, the recycled coarse aggregate is firstly cleaned, some cement mortar existing on the surface is removed, and if the cement mortar is remained on the surface of the recycled coarse aggregate, the water absorption rate is easily high, so that the strength of the prepared concrete is reduced. And then heating, decomposing the mortar remained on the surface of the recycled coarse aggregate after cleaning, and then grinding to reduce the pores of the recycled coarse aggregate. And then the polyolefin fiber with better water resistance and the accelerant are bonded on the recycled coarse aggregate through the silane coupling agent, so that the water absorption performance of the recycled coarse aggregate is effectively reduced, and the strength of the recycled aggregate concrete prepared from the obtained modified recycled coarse aggregate is enhanced.

Preferably, the weight ratio of the recycled coarse aggregate, the polyolefin fiber, the accelerator and the silane coupling agent is 1 (0.05-0.1): (0.03-0.05): 0.01-0.02).

By adopting the technical scheme, the weight ratio of the raw materials in the prepared modified recycled coarse aggregate is optimized, so that the reduction of the water absorption of the recycled coarse aggregate is facilitated, and the strength of the prepared recycled aggregate concrete is further enhanced.

Preferably, the accelerator comprises at least one of cationic rosin size and polyamide epichlorohydrin resin.

By adopting the technical scheme, the promoters of the cationic rosin size and the polyamide epichlorohydrin resin are used for being firmly combined with the polyolefin fiber, so that the water absorption of the modified recycled coarse aggregate is further reduced, and the strength of the prepared recycled aggregate concrete is further enhanced.

Preferably, in the step a1, the recycled coarse aggregate is ultrasonically cleaned for 3-5 times by using an acetic acid solution, and the concentration of the acetic acid solution is 0.2-0.4 mol/L.

By adopting the technical scheme, the effect of ultrasonic cleaning of cement mortar on the surface of the recycled coarse aggregate is better, and loose particles on the surface of the recycled coarse aggregate are removed; in the ultrasonic cleaning process, the cement mortar on the surface of the recycled coarse aggregate is dissolved by acetic acid solution, and the cement mortar on the surface of the recycled coarse aggregate, which is firmer, is removed; the effect of removing cement mortar on the surface of the recycled aggregate concrete is further enhanced by the matching of ultrasonic cleaning and acetic acid solution, so that the water absorption of the recycled coarse aggregate is reduced, and the strength of the recycled aggregate concrete is enhanced.

Preferably, the raw materials of the recycled aggregate concrete also comprise 11-24 parts by weight of reinforcing agent, and the reinforcing agent consists of poplar fiber and n-dodecyl mercaptan in a mass ratio of 1 (0.1-0.2).

By adopting the technical scheme, the n-dodecyl mercaptan is matched with the poplar fiber to modify the poplar fiber, so that the poplar fiber is matched with the polyurethane fiber and the polyvinyl alcohol fiber together, the water absorption of the concrete is further reduced, and the strength of the recycled aggregate concrete is further enhanced.

Preferably, the raw materials of the recycled aggregate concrete also comprise 10-20 parts by weight of rubber powder.

By adopting the technical scheme, the rubber powder, the polyurethane fiber, the polyethylene fiber and the modified recycled coarse aggregate are matched together, so that the water absorption rate of the concrete is reduced, the elasticity of the concrete is improved, and the strength of the concrete is enhanced.

In a second aspect, the application provides a preparation method of recycled aggregate concrete, which adopts the following technical scheme: a preparation method of recycled aggregate concrete comprises the following steps:

s1, mixing the modified recycled coarse aggregate, the natural sand, the cement and 40-80 parts by weight of water, adding the fly ash, the mineral powder and the silica fume powder after uniformly mixing, and uniformly mixing to obtain a first mixture;

and S2, uniformly mixing the first mixture with the butylbenzene emulsion, the polyurethane fiber, the polyvinyl alcohol fiber and the rest water, adding the water reducing agent, and uniformly mixing to obtain the recycled aggregate concrete.

By adopting the technical scheme, part of water is mixed with substances such as modified recycled coarse aggregate, and then powder substances such as fly ash and silica fume powder are added to fill up the pores between the natural sand and the coarse aggregate; then adding other raw materials and mixing uniformly to endow the recycled coarse aggregate with better strength.

Preferably, the reinforcing agent and the rubber powder are added in the step S2, and are added together with the butylbenzene emulsion, the polyurethane fiber, the polyvinyl alcohol fiber and the rest water.

By adopting the technical scheme, the reinforcing agent and the rubber powder are added and matched with the polyurethane fiber, the polyvinyl alcohol and the modified recycled coarse aggregate, so that the strength of the recycled aggregate concrete is further enhanced.

In summary, the present application has the following beneficial solutions:

1. in the application, the butylbenzene emulsion, the polyurethane fiber and the polyvinyl alcohol fiber are added, and the regenerated coarse aggregate is modified, so that the water absorption rate of the regenerated aggregate concrete is reduced, and the strength of the concrete is enhanced. The regenerated coarse aggregate is modified by adopting the polyolefin fiber, the accelerant and the silane coupling agent, so that the modified regenerated coarse aggregate is endowed with lower water absorption, and the strength of the prepared regenerated aggregate concrete is further enhanced.

2. In the application, cationic rosin size and polyamide epichlorohydrin resin are preferably used as accelerators, and the accelerators are matched with polyolefin fibers, so that the water absorption rate of the modified recycled coarse aggregate is further reduced, and the strength of the prepared recycled aggregate concrete is further enhanced. Meanwhile, the reinforcing agent and the rubber powder are added into the recycled aggregate concrete, so that the strength of the recycled aggregate concrete is further enhanced.

3. In the application, in the process of preparing the modified recycled coarse aggregate, firstly, the recycled coarse aggregate is subjected to ultrasonic cleaning by adopting an acetic acid solution, so that cement mortar on the surface of the recycled coarse aggregate is effectively removed; the water absorption of the recycled coarse aggregate is reduced, and the strength of recycled aggregate concrete is enhanced; then mixing all the raw materials to prepare the recycled aggregate concrete with higher strength.

Detailed Description

The present application is described in further detail below.

The components and manufacturers in the examples are shown in Table 1.

TABLE 1 Components and manufacturers

Components	Model/specification	Manufacturer of the product
			Recycled coarse aggregate	Type 2 macadam	Dongfu Shi Co Ltd of Ma City
Polyolefin fibers (Polypropylene fiber)	9003-07-0	Jinan Hui Jingchuan commercial Co Ltd
			Cationic rosin size	BY-03	ANHUI BAIYI BIOLOG TECHNOLOGY Co.,Ltd.
Polyamide epichlorohydrin resin	SQ-2	Xindi chemical Co Ltd of Qingzhou city
			Chitosan	fdqwrq	Jiangsu Caosheng Biotech Co., Ltd
Silane coupling agent	kh-550	Jinan Rong Guanghu chemical Co., Ltd
			Portland cement	PO42.5	Sea snail cement
Natural sand	70-100 mesh	Beijing Yulu building engineering Co Ltd
			Fly ash	zc001	Hangzhou Cheng Ca products Ltd
Mineral powder	Stage S95	Lingshou county Dingwang mineral product processing factory
			Silica fume powder	1500 mesh screen	Guishou county Jiagong mineral products Limited
Butylbenzene emulsion	LW-93	Wuhan La Na Bai pharmaceutical chemical Co Ltd
			Polyurethane fiber	400KN	The Shandong road material hasLimited company
Polyvinyl alcohol fiber	First stage	Shandong Haosen New Material Co Ltd
			Polycarboxylic acid water reducing agent	HQ-1(S)	Hangzhou Shibao building materials science and technology Co Ltd
Poplar fiber	CC-DMPT02	Weian county de gus cellulose plant
			N-dodecyl mercaptan	LA-7Q	Shandong Li-ang New Material science and technology Co Ltd
Rubber powder	60 mesh	Dongying Guang Shang Co Ltd
			Pumping agent	YL-300RBJ	Xinxiang Zhongtun Electromechanical Equipment Co., Ltd.
Granulated blast furnace slag powder	S95	Tangshan Industrial building materials Co Ltd
			Recycled fine aggregate	0.074-2mm	Wu Shi Dong of Macheng CityCompany of industry Ltd

Preparation example

Preparation example 1A modified recycled coarse aggregate, comprising the specific components and weights shown in Table 2, was prepared by the following steps:

a1, washing the recycled coarse aggregate with water for 3 times, wherein the washing time is 20min each time, 1500L each time is used, heating at 340 ℃ for 3h, grinding with a concrete grinder, and crushing with a concrete crusher to obtain the processed recycled coarse aggregate;

a2, mixing and stirring the treated recycled aggregate, the polypropylene fiber and the silane coupling agent at a stirring speed of 600r/min, and uniformly mixing to obtain the modified recycled aggregate.

Preparation example 2 a modified recycled coarse aggregate, which is different from preparation example 1 in that an accelerator was added to and mixed in step a2, and the specific components and weights included are shown in table 2.

Preparation examples 3 to 4 a modified recycled coarse aggregate, which is different from preparation example 2 in the raw materials and weight ratio of each component, and the specific components and weights included are shown in table 2.

Preparation examples 5 to 6A modified recycled coarse aggregate was different from preparation example 4 in the specific components of the accelerator and included specific components and weights as shown in Table 2.

Preparation example 7A modified recycled coarse aggregate, which is different from preparation example 2 in that the recycled coarse aggregate is ultrasonically cleaned 3 times by using an acetic acid solution in step A1, wherein the cleaning time is 20min each time; the concentration of the acetic acid solution is 0.4mol/L, and the dosage is 1500L each time.

Preparation example 8A modified recycled coarse aggregate, which is different from preparation example 7 in that the recycled coarse aggregate is ultrasonically cleaned 5 times in step A1 by using an acetic acid solution, wherein the cleaning time is 20min each time; the concentration of the acetic acid solution is 0.2mol/L, and the dosage is 1500L each time.

Preparation examples 9 to 10 modified recycled coarse aggregate, which is different from preparation example 2 in that in step A1, the recycled coarse aggregate is ultrasonically cleaned for 3 times with 20min each time by using an acetic acid solution; the concentration of the acetic acid solution is 0.4mol/L, and the dosage is 1500L each time; heating at 360 deg.C; meanwhile, the specific components of the raw materials are different, and the specific components and the weight are shown in table 2.

TABLE 2 specific compositions and weights of preparations 1 to 6 and 9 to 10

Examples

Example 1A recycled aggregate concrete comprising the specific components and weights shown in Table 3 was prepared by the following steps:

s1, mixing and stirring the modified recycled coarse aggregate in the preparation example 1, the natural sand, the cement and 60kg of water, wherein the mixing and stirring speed is 800 r/min. After uniformly mixing, adding the fly ash, the mineral powder and the silica fume powder, mixing and stirring at the stirring speed of 1000r/min, and uniformly stirring to obtain a first mixture;

and S2, mixing and stirring the first mixture, the butylbenzene emulsion, the polyurethane fiber, the polyvinyl alcohol fiber and the rest water at the stirring speed of 1000r/min, adding the water reducing agent after uniformly stirring, mixing and stirring at the stirring speed of 1200r/min, and uniformly stirring to obtain the recycled aggregate concrete.

Example 2A recycled aggregate concrete was different from example 1 in specific components and weights, and the specific components and weights included were as shown in Table 3.

Examples 3 to 11A recycled aggregate concrete which is different from example 1 in that the modified recycled coarse aggregate had a weight of 800 kg; preparation examples 2 to 10 correspond to the modified recycled coarse aggregates in examples 3 to 11, respectively.

Examples 12 to 13 a recycled aggregate concrete, which is different from example 1 in that a reinforcing agent was added in step S2, and it was added together with styrene-butadiene emulsion, polyurethane fiber, polyvinyl alcohol fiber and the remaining water, and the specific components and weights thereof were included as shown in table 3.

Examples 14 to 15 a recycled aggregate concrete, which is different from example 13 in that rubber powder was added in step S2, and concrete components and weights thereof included together with styrene-butadiene emulsion, polyurethane fiber, polyvinyl alcohol fiber and the remaining water were as shown in table 3.

Examples 16 to 17A recycled aggregate concrete, which is different from example 11 in that reinforcing agents and rubber powder were added together with styrene-butadiene emulsion, polyurethane fiber, polyvinyl alcohol fiber and the remaining water, and the specific components and weights thereof were as shown in Table 3.

TABLE 3 specific Components and weights of the examples

Comparative example

Comparative example 1 a recycled aggregate concrete, which is different from example 1 in that polyurethane fiber is not contained.

Comparative example 2 a recycled aggregate concrete, which is different from example 1 in that polyvinyl alcohol fiber is not contained.

Comparative example 3 a recycled aggregate concrete, which is different from example 1 in that polyurethane and polyvinyl alcohol fibers are not contained.

Comparative example 4 a recycled aggregate concrete, which is different from example 1 in that it does not contain a styrene-butadiene emulsion.

Comparative example 5 a recycled aggregate concrete, which is different from example 1 in that it does not contain styrene-butadiene emulsion, polyurethane fiber and polyvinyl alcohol fiber.

Comparative example 6 a recycled aggregate concrete was distinguished from example 1 in that no modification was made to the recycled coarse aggregate.

Comparative example 7A recycled aggregate concrete comprising the following components in percentage by weight: 15% of cement and 20% of recycled fine aggregate; 30% of recycled coarse aggregate, 7% of admixture, 2.5% of concrete pumping aid in the weight of the cement and the admixture, and the balance of water; the admixture is fly ash and granulated blast furnace slag powder; the types and manufacturers of the included specific components are shown in table 1.

The preparation method comprises the following steps: mixing and stirring cement, recycled fine aggregate, recycled coarse aggregate, admixture, concrete pumping aid and water at the stirring speed of 1000r/min, and uniformly stirring to obtain the recycled aggregate concrete.

Detection method

Experiment one: experimental sample of the water content of the modified recycled coarse aggregate: taking 6kg of the modified recycled coarse aggregates of preparation examples 1 to 10 and 6kg of the unmodified recycled coarse aggregate adopted in the comparative example 6, placing the modified recycled coarse aggregates on a flat plate, uniformly mixing the modified recycled coarse aggregates and the unmodified recycled coarse aggregate in a natural state, and piling the modified recycled coarse aggregates into a pile, wherein 5 parts of the modified recycled coarse aggregates are used in each preparation example; the recycled coarse aggregate in comparative example 6 was a blank group.

An experimental instrument: forced air drying cabinet (temperature controlled at 105 ℃); a balance; a square hole sieve (one sieve with the hole diameter of 4.75 mm); a container; an enamel tray.

The experimental method comprises the following steps: the detection is carried out by referring to a moisture content detection method of construction pebbles and gravels in GB/T14685-2011, and the specific steps are as follows:

placing the preparation example in a container containing water, soaking for 24h, taking out from the water, wiping off water on the surface of the particles by using a wet towel to obtain a saturated dry face sample, and immediately weighing the sample until the mass is 1 g; drying the saturated dried noodle sample in a drying box to constant weight, wherein the temperature of the drying box is 105 ℃; after cooling to room temperature, the mass was weighed out to the nearest 1 g. And calculating the water content of the experimental sample according to the calculation method of the water absorption recorded in the national standard. The above experiment was performed for each of 5 production examples 1, and the average of the water contents of the 5 production examples 1 was determined as the final water content of production example 1.

The water contents of preparation examples 1 to 10 and the blank group were obtained by the above-described experimental methods, respectively.

The experimental results are as follows: the water contents of preparation examples 1 to 10 are shown in Table 4.

TABLE 4 Water content test results of modified recycled coarse aggregates of test samples 1 to 10

As is clear from the data in Table 4, the water contents of the prepared examples 1 to 10 were 0.83 to 1.58% and the water contents of the blank group were 5.13%, which indicates that the water contents of the modified recycled coarse aggregate were effectively reduced after the recycled coarse aggregate was modified.

As is clear from comparison between preparation example 1 and the blank group, the modified recycled coarse aggregate had a low water content, indicating that the modified recycled coarse aggregate had a reduced water absorption. The polyolefin fiber has certain hydrophobic property, and is bonded on the surface of the recycled coarse aggregate through the silane coupling agent, so that the water absorption property of the recycled coarse aggregate is effectively reduced. Comparing the preparation examples 1 and 2, after the accelerant is added, the accelerant is matched with the polyolefin fiber together, and the water absorption performance of the modified recycled coarse aggregate is reduced. As can be seen from comparison between preparation examples 2 and 3 to 4, when cationic rosin size and polyamide epichlorohydrin resin are preferably used as the accelerator, the cationic rosin size and the polyamide epichlorohydrin resin are firmly bonded to the polyolefin fiber which is easy to generate static electricity, and the good water resistance is achieved, so that the water absorption performance of the modified recycled coarse aggregate is further reduced, and the water content is reduced.

It is understood from comparison between preparation example 4 and preparation examples 5 to 6 that the weight ratio of the modified recycled coarse aggregate is preferable and the water content of the modified recycled coarse aggregate is further reduced. Comparing preparation example 2 with preparation examples 7-8, it can be seen that the acetic acid solution is adopted to carry out ultrasonic cleaning, and the concentration of the acetic acid solution is controlled, so that cement mortar existing on the surface of the recycled coarse aggregate is effectively removed, the water absorption rate is reduced, and the water absorption performance of the modified recycled coarse aggregate can be reduced. As can be seen from comparison of preparation examples 2 and 9 to 10, the components of the accelerator and the components of the modified recycled coarse aggregate are preferable, and the preparation step is also preferable, and the modified recycled coarse aggregate having a low water content is obtained.

Experiment two: concrete compressive strength experiment sample: examples 1 to 17 and comparative examples 1 to 7 were each prepared as a test piece of a cubic body having a side of 150mm, and designated as experimental samples 1 to 17 and comparative samples 1 to 7, respectively.

An experimental instrument: pressure tester (from the yan w series, the kn wining test instruments ltd).

The experimental method comprises the following steps:

compressive strength test: the compressive strength of the self-compacting concrete is evaluated according to the compressive strength test in GB/T50081-2019 'Specification of Experimental methods for physical and mechanical properties of self-compacting concrete'.

When the experimental sample reaches the experimental age, namely 28 days, the experimental sample is taken out from the maintenance place and is placed in front of a compression-resistant experimental machine, and the surface of the experimental sample and the upper and lower bearing plate surfaces are wiped clean; the side surface of the experimental sample during molding is taken as a pressure bearing surface. The experimental sample is placed on a lower pressing plate or a base plate of the compression testing machine, and the center of the experimental sample is aligned with the center of the lower pressing plate of the compression testing machine. And starting the compression test machine, and uniformly contacting the surface of the test sample 1 with the upper and lower bearing plates or the steel base plate. In the experimental process, the load is continuously and uniformly added, and the loading speed is 1.0 MPa/s. When the compressive strength of the experimental sample is less than 30MPa, the loading speed is preferably 0.5 MPa/s; when the compressive strength of the experimental sample is 60MPa, the loading speed is preferably 0.8 MPa/s; when the compressive strength of the experimental sample is not less than 60MPa, the loading speed is preferably 1.0 MPa/s. When the loading speed of the compression test machine is manually controlled, when the test sample is close to the damage and begins to deform rapidly, the accelerator of the compression test machine is stopped and adjusted until the test sample is damaged, the damage load is recorded at the moment, and the compression strength of the test sample is calculated.

The experimental results are as follows: the compression strength tests of the experimental samples 1 to 17 and the comparative samples 1 to 7 are shown in Table 4.

Experiment three: concrete flexural strength experiment sample: samples, which were 150mm × 150mm × 600mm prism test pieces, were prepared according to examples 1 to 17 and comparative examples 1 to 7, and the samples obtained according to examples 1 to 17 were designated as experimental samples 1 to 17, respectively, and the samples obtained according to comparative examples 1 to 7 were designated as comparative samples 1 to 7, respectively, and 5 samples were provided for each of experimental samples 1 to 17 and comparative samples 1 to 7.

An experimental instrument: pressure tester (from the yan w series, the kn wining test instruments ltd).

The experimental method comprises the following steps: the flexural strength of the experimental sample is evaluated by referring to the flexural strength test in the experimental method standard for physical and mechanical properties of concrete of GB/T50081-2019, for example, the flexural strength of 5 experimental samples 1 is respectively detected, and then the average value of the flexural strength of the 5 experimental samples 1 is taken as the final flexural strength of the experimental sample 1.

The experimental results are as follows: flexural strength tests of the experimental samples 1 to 17 and the comparative samples 1 to 7 are shown in Table 5.

TABLE 5 results of the intensity measurement test of the test samples 1 to 17 and the comparative samples 1 to 7

As can be seen from Table 5, the 28d compressive strength of the test samples 1-17 is 47.7-56.3MPa, and the 28d flexural strength is 8.4-14.4 MPa; the 28d compressive strength of comparative samples 1-7 was 19.7-31.3 MPa; the 28d flexural strength is 3.2-6.6 MPa. The compressive strength and the flexural strength of the experimental samples 1 to 17 are higher than those of the comparative samples 1 to 7, which shows that the recycled aggregate concrete of the experimental samples 1 to 7 has higher strength.

Comparative experiment sample 1 and comparative samples 1-3, polyurethane fiber and polyvinyl alcohol fiber; comparing the experimental sample 1 and the comparative samples 1 to 5, it can be seen that the water absorption of the modified recycled coarse aggregate can be reduced by optimizing the components and the preparation steps of the modified recycled coarse aggregate, so that the density of the modified recycled coarse aggregate is improved, and the strength of the recycled aggregate concrete is enhanced; it can be seen from comparison of experimental sample 1 and comparative sample 6 that the compressive strength and the flexural strength of the recycled aggregate concrete are enhanced after the recycled aggregate is modified.

Comparing the experimental sample 1 and the experimental samples 3-5, it can be seen that the water absorption of the modified recycled coarse aggregate is reduced and the compressive strength and the flexural strength of the recycled aggregate concrete are enhanced after the accelerator is added and preferably selected. Compared with the experimental samples 5-7, the proportion of each component is preferably selected, so that the matching effect of the polyolefin fiber, the accelerant and the recycled coarse aggregate is better, the water absorption of the recycled coarse aggregate is reduced, and the prepared recycled aggregate concrete has higher strength; comparing the experimental sample 3 with the experimental samples 8-9, it can be seen that the acetic acid solution is adopted and the ultrasonic cleaning is performed, so that cement mortar existing on the surface of the recycled coarse aggregate is effectively removed, the water absorption rate is reduced, the water absorption performance of the modified recycled coarse aggregate can be reduced, and the strength of the recycled aggregate concrete is further enhanced. Comparing the experimental sample 3 with the experimental samples 10-11, the modification method is optimized, and the composition and the proportion of the raw materials are controlled, so that the recycled aggregate concrete with higher compressive strength and flexural strength is obtained.

Comparing the experimental sample 1 with the experimental samples 12-13, the poplar fiber has better strength and elasticity by adding the reinforcing agent poplar fiber and n-dodecyl mercaptan; the n-dodecyl mercaptan carries out hydrophobic modification on the surface of the poplar fiber, so that the poplar fiber with good strength is endowed with better hydrophobic performance, the water absorption of concrete is further reduced, and the compressive strength and the flexural strength of the recycled aggregate concrete are enhanced; comparing the experimental sample 13 with the experimental samples 14-15, it can be seen that after the rubber powder is added, the rubber powder is used as a high-density elastomer, is not only hydrophobic, but also has high stability, and after the rubber powder is added into the recycled aggregate concrete, the rubber powder is combined with the modified recycled coarse aggregate, so that the strength of the recycled aggregate concrete is further enhanced. Comparing the experimental sample 11 with the experimental samples 16 to 17, it can be seen that when the components of the raw materials are optimized, and the reinforcing agent and the rubber powder are added to be matched with each other, the compressive strength and the flexural strength of the recycled aggregate concrete are improved, and are greatly improved.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.