CN114436621A - Alkali-activated composite recycled powder recycled aggregate pervious concrete and preparation method thereof - Google Patents

Abstract

The invention provides an alkali-excited composite regenerated powder regenerated aggregate permeable concrete, comprising 6-16 parts by weight of fly ash, 5-15 parts of mineral powder, 2-6 parts of brick powder, 2-8 parts of water, 30-50 parts of single particle size coarse aggregate, 10-30 parts of regenerated coarse aggregate, and 4-6 parts of alkaline activator. Add single particle size coarse aggregate, recycled coarse aggregate and water with 20% to 30% of the total water into the mixer, stir for 30 seconds, then add mineral powder, fly ash, silica fume, brick powder and the remaining water in sequence , continue to stir for 1 minute and 30 seconds; finally add water glass and polycarboxylate water reducer, and continue to stir for 2 minutes, the porous concrete is formed; and then the mold is installed and vibrated to form, with mold curing, demoulding, and curing to 28d age Finished pervious concrete. The product not only has the characteristics of rough surface, strong water permeability, good ductility, etc., but also effectively utilizes solid waste brick powder, recycled aggregates and solid waste mineral admixtures, etc., so that the waste can be reused as a resource.

Description

Alkali-activated composite recycled powder recycled aggregate pervious concrete and preparation method thereof

Technical Field

The invention relates to a concrete and a preparation method of a product thereof, in particular to alkali-activated composite recycled powder recycled aggregate permeable concrete and a preparation method of a product thereof, belonging to the technical field of building materials.

Background

With the rapid development of urbanization, the ground hardening of the traditional concrete makes the ground rainwater difficult to rapidly infiltrate, so that the inland inundation disasters of large and medium cities in China are frequent, and the problem is particularly prominent in recent years due to frequent occurrence of extreme rainstorm weather. Based on this, scholars propose the concept of sponge city. The pervious concrete is one of important ways for realizing sponge cities, and has excellent water seepage, noise reduction, skid resistance and other properties. Meanwhile, the rapid development of urbanization also generates a large amount of construction waste, wherein the amount of waste concrete and masonry generated by removal and construction is huge.

The pervious concrete is also called porous concrete, is green concrete for regulating urban ecology, and the common pervious concrete building blocks have higher strength, durability and permeability. However, most of the existing pervious concrete in the market at present is prepared by mixing coarse aggregate with single particle size, cement, an additive and water according to a certain proportion, and the coarse aggregate with single particle size mostly adopts natural sandstone aggregate.

Patent application CN112500087A discloses a high-strength high-toughness pervious cement concrete and a preparation method thereof. The method is characterized in that certain ultrashort-cut polyethylene fibers and calcium carbonate whiskers are doped to improve the strength and toughness of the pervious concrete. However, 335-385 kg of cement, 155-195 kg of machine-made sand and 1300-1500 kg of stones are required to be used in each cubic meter of the pervious concrete, the high cement dosage and the sandstone aggregate dosage are difficult to meet the requirement of the future double-carbon strategy in China, and the resource utilization of wastes is not realized.

Patent application CN108249859A discloses an alkali-activated cementitious material pervious concrete and a preparation method thereof. The method is characterized in that fly ash, mineral powder and cement are compounded, and an alkali activator, single-particle-size aggregate, a water reducing agent and water are added to prepare the pervious concrete. However, 3% -8% of cement and 60% -80% of natural aggregate are still used in the pervious concrete, carbon emission is still high, and the concrete is cured by steam, so that the material is poor in practicability for large-area cast-in-place concrete pavements.

The research and application status of the recycled aggregate pervious concrete are reviewed in the study progress of recycled aggregate pervious concrete (concrete and cement products 2021, (07): 1-6) of Shilitong and Benxiangbo, and it can be found that the existing recycled aggregate pervious concrete partially utilizes recycled coarse aggregate, so that the recycling of waste construction waste is realized to a certain extent, but the existing recycled aggregate pervious concrete is not utilized for the recycled powder such as brick powder, concrete powder, mortar powder and the like with smaller particles generated after the waste construction waste is crushed. These recycled powders that are not properly disposed of also pose a significant threat to the environment and waste resources.

It can be seen from the analysis of the above patents and academic papers that the existing technical means is not enough to fully digest the construction waste, the coarse aggregate with single particle size mainly adopts natural sandstone aggregate, the production cost is high, the exploitation of the natural sandstone aggregate is increased, and simultaneously, a large amount of silicate cement, a product with high energy consumption, is still needed, and the ecological sustainable development of the construction industry cannot be realized.

Disclosure of Invention

Aiming at the problems and defects in the prior art, the invention aims to provide the alkali-activated composite recycled powder recycled aggregate pervious concrete which not only has good compressive strength, flexural strength, permeability coefficient and porosity, but also can be used for recycling garbage and waste materials, so that the exploitation of natural gravel aggregates is reduced, and the ecological sustainable development of the building industry is realized.

The invention aims to provide alkali-activated composite recycled powder recycled aggregate pervious concrete which is characterized by comprising 6-16 parts by weight of fly ash, 5-15 parts by weight of mineral powder, 2-6 parts by weight of brick powder, 2-8 parts by weight of water, 30-50 parts by weight of single-particle-size aggregate, 10-30 parts by weight of recycled aggregate and 4-6 parts by weight of an alkali activator.

In order to achieve the technical effects of improving the workability of pervious concrete and improving the mechanical property of a concrete hardened substance, the alkali-activated composite recycled powder recycled aggregate pervious concrete further comprises 0.1-3 parts by weight of silica fume and/or 0.1-2 parts by weight of a polycarboxylic acid water reducing agent.

The aggregate with the single particle size is stone with the particle size of 10-20 mm.

The brick powder is solid waste which is sieved to be 1.0-2.0 mm in particle size.

The recycled aggregate is construction waste which is sieved into particles with the particle size of 10-20 mm, and the recycled aggregate is in a saturated surface dry state before being mixed.

The alkali activator is a 1.5-modulus water glass solution.

The invention also aims to provide a preparation method of the alkali-activated composite recycled powder recycled aggregate pervious concrete, which comprises the following steps:

1) weighing fly ash, mineral powder, brick powder, water, single-particle-size aggregate, recycled aggregate and an alkaline activator according to a formula proportion for later use;

2) adding aggregate with single particle size, recycled aggregate and water with the total water amount of 20-30 parts into a stirrer, stirring for 20-40 seconds, then sequentially adding mineral powder, fly ash, brick powder and the rest 60-70 parts of water, and continuously stirring for 1-2 minutes; finally, adding an alkaline activator, and continuing to stir for 1-3 minutes to form porous concrete;

3) filling the porous concrete obtained in the step 2) into a mould for vibration molding twice;

4) covering a plastic film on the surface of the molded test piece with the mold, and removing the mold after 24 hours;

5) and (5) after demoulding, preserving heat and moisture for maintenance for not less than 3 days until 28 days, thus obtaining the finished product of the pervious concrete.

While the mineral powder and the fly ash are added, silica fume can also be added.

The alkali activator is added, and the polycarboxylate superplasticizer can be added at the same time.

The invention aims to prepare pervious concrete and various pervious blocks required by cities by replacing natural sandstone aggregates with solid wastes and replacing traditional cement with the advantage of high strength of alkali-activated cementing materials, and prepare products with high strength, durability and permeability by using resources such as waste mineral admixtures and the like under the effects of meeting the requirements of green and safe development of cities and efficiently recycling construction wastes.

If the waste building garbage is treated by methods such as crushing, screening and the like to obtain the recycled coarse aggregate and the recycled brick powder, so that part of natural aggregate with short resources is replaced, and the green recycled aggregate pervious concrete is prepared, the urban ecological environment can be well regulated, a certain flood storage space is created for heavy rain flood, the garbage waste can be fully recycled, the exploitation of natural gravel aggregate is reduced, and the ecological sustainable development of the building industry is realized.

Compared with the prior art, the alkali-activated composite recycled powder recycled aggregate pervious concrete has the following beneficial effects:

1. the recycled aggregate pervious concrete has the characteristics of rough surface, strong water permeability, good ductility and the like, and has the most basic mechanical property, water permeability and durability. Meanwhile, the concrete does not need to be steamed, and is convenient for large-area cast-in-place pavement engineering application.

2. The alkali-activated preparation process has the advantages of low energy consumption, small emission, simple preparation process, high hardness and strength, heat resistance, high temperature resistance, acid corrosion resistance and the like.

3. The solid waste brick powder, the recycled coarse aggregate, the waste mineral admixture and the like are effectively utilized, so that the waste forms resources for recycling.

Detailed description of the invention

For a better understanding of the present invention, the following examples are given in connection with the accompanying drawings, which are not intended to limit the present invention.

The materials used in the examples and comparative examples were as follows:

the alkali activator is: the water glass solution produced by the Changlong sodium silicate factory in Guyi city has the modulus of 3.22, the baume degree of 40 and the content of sodium oxide of 9.0 parts. The experiment adopts water glass with the modulus of 1.5, and the water glass with the modulus is prepared by sodium hydroxide particles. The brick powder is a material with the solid waste screened to be 1.0-2.0 mm, the recycled aggregate is 10-20 mm of construction waste screened to be 1.0-2.0 mm, and the aggregate with the single particle size is 10-201.0-2.0 mm of stones.

Example 1

1) Weighing 6 parts of fly ash, 15 parts of mineral powder, 6 parts of brick powder, 8 parts of water, 30 parts of single-particle-size aggregate, 15 parts of saturated surface dry-state recycled aggregate and 4 parts of alkaline activator according to a formula proportion for later use;

2) adding the aggregate with the single particle size, the recycled aggregate and water with the total water amount of 20% into a stirrer, stirring for 40 seconds, then sequentially adding the mineral powder, the fly ash, the brick powder and the rest water, and continuing stirring for 2 minutes; finally, adding an alkaline activator, and continuing to stir for 2 minutes to form porous concrete;

3) filling the porous concrete obtained in the step 2) into a mould for vibration molding twice;

4) covering a plastic film on the surface of the molded test piece with the mold, and removing the mold after 24 hours;

5) and (5) after demoulding, preserving heat and moisture for maintenance for not less than 3 days until 28 days, thus obtaining the finished product of the pervious concrete.

Example 2

1) Weighing 11 parts of fly ash, 12 parts of mineral powder, 4 parts of brick powder, 5 parts of water, 50 parts of single-particle-size aggregate, 30 parts of saturated surface dry state recycled aggregate and 6 parts of alkaline activator according to the formula proportion for later use;

2) adding aggregate with single particle size, recycled aggregate and water with the total water amount of 25% into a stirrer, stirring for 30 seconds, then sequentially adding mineral powder, fly ash, brick powder and the rest water, and continuing stirring for 1.5 minutes; finally, adding an alkaline activator, and continuing to stir for 3 minutes to form porous concrete;

3) filling the porous concrete obtained in the step 2) into a mould for vibration molding twice;

4) covering a plastic film on the surface of the molded test piece with the mold, and removing the mold after 24 hours;

5) and (5) after demoulding, preserving heat and moisture for maintenance for not less than 3 days until 28 days, thus obtaining the finished product of the pervious concrete.

Example 3

1) Weighing 16 parts of fly ash, 5 parts of mineral powder, 2 parts of brick powder, 2 parts of water, 40 parts of single-particle-size aggregate, 10 parts of saturated surface dry state recycled aggregate and 5 parts of alkaline activator according to the formula proportion for later use;

2) adding aggregate with single particle size, recycled aggregate and water with the total water amount of 30% into a stirrer, stirring for 20 seconds, then sequentially adding mineral powder, fly ash, brick powder and the rest water, and continuing stirring for 1 minute; finally, adding an alkaline activator, and continuing to stir for 1 minute to form porous concrete;

3) filling the porous concrete obtained in the step 2) into a mould for vibration molding twice;

4) covering a plastic film on the surface of the molded test piece with the mold, and removing the mold after 24 hours;

5) and (5) after demoulding, preserving heat and moisture for maintenance for not less than 3 days until 28 days, thus obtaining the finished product of the pervious concrete.

Example 4

1) Weighing 5.5 parts of fly ash, 15 parts of mineral powder, 6 parts of brick powder, 8 parts of water, 30 parts of single-particle-size aggregate, 15 parts of saturated surface dry-state recycled aggregate, 4 parts of alkaline activator, 0.1 part of silica fume and 0.1 part of polycarboxylic acid water reducer according to the formula proportion for later use;

2) adding the aggregate with the single particle size, the recycled aggregate and water with the total water amount of 20% into a stirrer, stirring for 40 seconds, then sequentially adding the mineral powder, the fly ash, the silica fume, the brick powder and the rest water, and continuing stirring for 2 minutes; and finally, adding an alkaline activator and a polycarboxylic acid water reducing agent, continuing stirring for 3 minutes to form porous concrete, and performing the other steps in the same manner as in example 1.

Example 5

1) Weighing 9.5 parts of fly ash, 12 parts of mineral powder, 4 parts of brick powder, 5 parts of water, 50 parts of single-particle-size aggregate, 30 parts of saturated surface dry state recycled aggregate, 6 parts of alkaline activator, 1.5 parts of silica fume and 1 part of polycarboxylic acid water reducer according to the formula proportion for later use;

2) adding aggregate with single particle size, recycled aggregate and water with the total water amount of 25% into a stirrer, stirring for 30 seconds, then sequentially adding mineral powder, fly ash, silica fume, brick powder and the rest water, and continuing stirring for 1.5 minutes; and finally, adding an alkaline activator and a polycarboxylic acid water reducing agent, continuing stirring for 2 minutes to form porous concrete, and performing the other steps in the same manner as in example 1.

Example 6

1) Weighing 13 parts of fly ash, 5 parts of mineral powder, 2 parts of brick powder, 2 parts of water, 40 parts of single-particle-size aggregate, 10 parts of saturated surface dry state recycled aggregate, 5 parts of alkaline activator, 3 parts of silica fume and 2 parts of polycarboxylic acid water reducer according to a formula proportion for later use;

2) adding aggregate with single particle size, recycled aggregate and water with the total water amount of 30% into a stirrer, stirring for 20 seconds, then sequentially adding mineral powder, fly ash, silica fume, brick powder and the rest water, and continuing stirring for 1 minute; and finally, adding an alkaline activator and a polycarboxylic acid water reducing agent, continuing stirring for 1 minute to form porous concrete, and performing the other steps in the same manner as in example 1.

Example 7

1) Weighing 7 parts of fly ash, 6 parts of mineral powder, 2.6 parts of silica fume, 3 parts of brick powder, 44.9 parts of pebbles, 28.6 parts of recycled aggregate, 4.8 parts of alkali activator, 2.6 parts of water and 0.1 part of polycarboxylic acid water reducing agent according to the formula proportion.

2) Adding the stones, the recycled aggregate and 25 parts of water of the total water amount into a stirrer, stirring for half a minute, then sequentially adding the mineral powder, the fly ash, the silica fume, the brick powder and the remaining 65 parts of water, and continuously stirring for 90 seconds; finally, adding water glass and a polycarboxylic acid water reducing agent, and continuing stirring for 2 minutes to form porous concrete; the stirred permeable concrete of the building excitation cementing material is filled into a triple die with the diameter of 100 multiplied by 100mm for two times, and is formed by manual and mechanical vibration. Curing the molded product with a mold for 24 hours, and removing the mold; and (3) after demoulding, curing for 7 hours by steam at 70 ℃ to obtain the permeable concrete of the invention.

Example 8

1) Weighing 16 parts of fly ash, 5 parts of mineral powder, 2 parts of brick powder, 2 parts of water, 40 parts of single-particle-size aggregate, 15 parts of saturated surface dry state recycled aggregate, 5 parts of alkaline activator and 2 parts of polycarboxylic acid water reducer according to a formula proportion for later use;

2) adding aggregate with single particle size, recycled aggregate and water with the total water amount of 30% into a stirrer, stirring for 20 seconds, then sequentially adding mineral powder, fly ash, brick powder and the rest water, and continuing stirring for 1 minute; and finally, adding an alkaline activator and a polycarboxylic acid water reducing agent, continuing stirring for 1 minute to form porous concrete, and performing the other steps in the same manner as in example 1.

Example 9

1) Weighing 6 parts of fly ash, 15 parts of mineral powder, 6 parts of brick powder, 6 parts of water, 30 parts of single-particle-size aggregate, 15 parts of saturated surface dry-state recycled aggregate, 4 parts of alkaline activator and 3 parts of silica fume according to the formula proportion for later use;

2) adding aggregate with single particle size, recycled aggregate and water with the total water amount of 30% into a stirrer, stirring for 20 seconds, then sequentially adding mineral powder, fly ash, silica fume, brick powder and the rest water, and continuing stirring for 1 minute; finally, adding the alkaline activator, continuing to stir for 1 minute to form the porous concrete, and the rest steps are the same as the example 1.

Comparative example 1

The following inventors conducted comparative tests on various specifications of pervious concrete prepared in examples 1, 4, 7, 8 and 9 of the present invention and comparative example 1 (the preparation method is the same as example 1 except that the raw materials are only cement, single-particle-size coarse aggregate, recycled coarse aggregate, polycarboxylic acid water reducer and water) and comparative example 2 (the preparation method is the same as example 1 except that the raw materials are only cement, single-particle-size coarse aggregate, polycarboxylic acid water reducer and water), and examined the compressive strength, flexural strength, water permeability and porosity of the pervious concrete and calculated the production cost, respectively, and the specific results are shown in table 1 below.

TABLE 1 comparison of test results of examples and comparative examples

As can be seen from table 1, the alkali-activated solid waste recycled aggregate permeable concrete of the present invention is superior to comparative example 1 and comparative example 2 in compressive strength, flexural strength, permeability coefficient, porosity technical index and production cost economic index, and can perform resource utilization on garbage waste, reduce exploitation of natural sandstone aggregate, and realize ecological sustainable development of building industry.

Claims (8)

1. an alkali-excited composite regeneration powder regeneration aggregate permeable concrete is characterized in that: comprise 6～16 parts of fly ash, 5～15 parts of mineral powder, 2～6 parts of brick powder, 2～8 parts of water of weight portion parts, 30-50 parts of single particle size aggregate, 10-30 parts of recycled coarse aggregate, and 4-6 parts of alkaline activator. 2. a kind of alkali-excited composite regenerated powder regenerated aggregate pervious concrete according to claim 1, is characterized in that: also comprise 0.1～3 part of silica fume and/or 0.1～2 part of polycarboxylate water-reducing part of weight portion agent. 3 . The alkali-excited composite regenerated powder regenerated aggregate permeable concrete according to claim 1 , wherein the single particle size aggregate is a stone with a particle size of 10-20 mm. 4 . 4 . The alkali-excited composite regenerated powder regenerated aggregate permeable concrete according to claim 1 , wherein the brick powder is sieved into waste clay brick powder with a particle size of less than 1.0 mm. 5 . 5 . The alkali-excited composite regenerated powder regenerated aggregate permeable concrete according to claim 1 , wherein the regenerated aggregate is sieved into construction waste with a particle size of 10-20 mm. 6 . 6 . The alkali-excited composite regenerated powder regenerated aggregate permeable concrete according to claim 1 , wherein the alkali-excited agent is a water glass solution with a modulus of 1.5. 7 . 7. the preparation method of a kind of alkali-excited composite regeneration powder regeneration aggregate permeable concrete described in claim 1, is characterized in that, comprises the following steps: 1) Weigh fly ash, mineral powder, brick powder, water, single particle size aggregate, regenerated aggregate, and alkaline activator according to the formula ratio, and set aside for later use; 2) Add single particle size aggregate, recycled aggregate and 20% to 30% water of the total water into the mixer, stir for 20 to 40 seconds, then add mineral powder, fly ash, brick powder and the remaining water in sequence, Continue to stir for 1 to 2 minutes; finally add an alkaline activator, and continue to stir for 1 to 3 minutes to form porous concrete; 3) the porous concrete obtained in step 2) is charged into the mould twice and vibrated and formed; 4) After molding, the surface of the mold is covered with a plastic film to keep moisture for 24 hours, and the mold is removed; 5) After demoulding, the heat preservation and moisturizing maintenance shall be no less than 3d, and the finished product of permeable concrete shall be obtained after 28d. 8. the preparation method of a kind of alkali-excited composite regeneration powder regeneration aggregate permeable concrete described in claim 2, is characterized in that, comprises the following steps: 1) Weigh fly ash, mineral powder, brick powder, silica fume, water, single particle size aggregate, regenerated aggregate, alkaline activator, polycarboxylate water reducer according to the formula ratio, and set aside for later use; 2) Add single particle size aggregate, recycled aggregate and water with 20% to 30% of the total water into the mixer, stir for 20 to 40 seconds, and then add mineral powder, fly ash, silica fume, brick powder and the rest in sequence. Continue to stir for 1 to 2 minutes; finally add alkaline activator and polycarboxylate water reducer, and continue to stir for 1 to 3 minutes to form porous concrete; 3) the porous concrete obtained in step 2) is charged into the mould twice and vibrated and formed; 4) After molding, the surface of the specimen with mold is covered with plastic film, and the mold is removed within 24 hours; 5) After demoulding, the heat preservation and moisturizing maintenance shall be no less than 3d, and the finished product of permeable concrete shall be obtained after 28d.