CN116535164A - Recycled concrete prepared from waste concrete as raw material and preparation method thereof - Google Patents
Recycled concrete prepared from waste concrete as raw material and preparation method thereof Download PDFInfo
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- CN116535164A CN116535164A CN202310516997.5A CN202310516997A CN116535164A CN 116535164 A CN116535164 A CN 116535164A CN 202310516997 A CN202310516997 A CN 202310516997A CN 116535164 A CN116535164 A CN 116535164A
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- 239000002699 waste material Substances 0.000 title claims abstract description 142
- 238000002360 preparation method Methods 0.000 title claims abstract description 52
- 239000002994 raw material Substances 0.000 title claims abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 59
- 239000000835 fiber Substances 0.000 claims abstract description 50
- 239000004115 Sodium Silicate Substances 0.000 claims abstract description 36
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910052911 sodium silicate Inorganic materials 0.000 claims abstract description 36
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 35
- 229920005646 polycarboxylate Polymers 0.000 claims abstract description 35
- 239000002202 Polyethylene glycol Substances 0.000 claims abstract description 27
- 229920001223 polyethylene glycol Polymers 0.000 claims abstract description 27
- 238000002156 mixing Methods 0.000 claims abstract description 18
- 239000004568 cement Substances 0.000 claims abstract description 17
- 239000000463 material Substances 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 5
- 229910052599 brucite Inorganic materials 0.000 claims description 25
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 23
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 23
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 23
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 23
- 239000007788 liquid Substances 0.000 claims description 16
- 238000003756 stirring Methods 0.000 claims description 15
- 238000002791 soaking Methods 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 4
- 238000012216 screening Methods 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 claims description 2
- 239000004917 carbon fiber Substances 0.000 claims description 2
- 239000010962 carbon steel Substances 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 2
- 230000000052 comparative effect Effects 0.000 description 17
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- 239000011148 porous material Substances 0.000 description 9
- 239000004576 sand Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 239000000378 calcium silicate Substances 0.000 description 4
- 229910052918 calcium silicate Inorganic materials 0.000 description 4
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000011049 filling Methods 0.000 description 4
- 230000008595 infiltration Effects 0.000 description 4
- 238000001764 infiltration Methods 0.000 description 4
- UFWIBTONFRDIAS-UHFFFAOYSA-N naphthalene-acid Natural products C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000000084 colloidal system Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 239000008030 superplasticizer Substances 0.000 description 2
- 239000011398 Portland cement Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000005923 long-lasting effect Effects 0.000 description 1
- 125000001624 naphthyl group Chemical group 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/10—Coating or impregnating
- C04B20/1055—Coating or impregnating with inorganic materials
- C04B20/1077—Cements, e.g. waterglass
- C04B20/1085—Waterglass
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The present application relates to the field of recycled concrete, and more particularly, to recycled concrete prepared from waste concrete and a preparation method thereof. The recycled concrete prepared from the waste concrete comprises the following raw materials in parts by weight: 70-80 parts of water, 350-400 parts of modified waste concrete, 500-550 parts of coarse aggregate, 0-20 parts of admixture, 145-155 parts of cement and 0-20 parts of fiber; the modified waste concrete comprises the following preparation raw materials: 400-500 parts of water, 1-5 parts of polyethylene glycol, 90-110 parts of waste concrete, 1.8-4.5 parts of polycarboxylate water reducer and 3.6-7.5 parts of sodium silicate; the preparation method comprises the following steps: mixing water, cement, fiber and admixture to obtain a primary mixed material; and uniformly mixing the primary mixed material with coarse aggregate and modified waste concrete to obtain a finished product. The method has the advantage of improving the strength of the recycled concrete.
Description
Technical Field
The present application relates to the field of recycled concrete, and more particularly, to recycled concrete prepared from waste concrete and a preparation method thereof.
Background
With the ever-increasing urban housing renewal and municipal movement, a number of construction waste is produced. If the construction waste is not reasonably recycled, serious pollution to the environment is easy to cause, and resource waste is caused. Accordingly, the recycled concrete related art is natural.
The recycled concrete is prepared by crushing, cleaning and grading waste concrete blocks, mixing with grading according to a certain proportion, partially or completely replacing natural aggregates such as sand and stone, and adding cement, water and the like.
The recycled concrete can fully utilize the resource recovery, so that the cost is saved; however, recycled aggregate used in recycled concrete has many corners and uneven surfaces, and is accompanied by a large amount of cement particle powder, which results in low strength of recycled aggregate and also affects the performance of recycled concrete. Therefore, there is still a need for improvement.
Disclosure of Invention
In order to improve the strength of recycled concrete, the application provides recycled concrete prepared from waste concrete and a preparation method thereof.
In a first aspect, the present application provides a recycled concrete prepared from waste concrete, which adopts the following technical scheme:
the recycled concrete prepared from the waste concrete comprises the following raw materials in parts by weight: 70-80 parts of water, 350-400 parts of modified waste concrete, 500-550 parts of coarse aggregate, 0-20 parts of admixture, 145-155 parts of cement and 0-20 parts of fiber;
the modified waste concrete comprises the following preparation raw materials: 400-500 parts of water, 1-5 parts of polyethylene glycol, 90-110 parts of waste concrete, 1.8-4.5 parts of polycarboxylate water reducer and 3.6-7.5 parts of sodium silicate.
Since the main cause of the deterioration of the recycled concrete is derived from the waste concrete, the waste concrete is modified by using a specific raw material by adopting the above-mentioned technical scheme. Under the joint coordination of polyethylene glycol, polycarboxylate water reducer and sodium silicate, the infiltration of the polycarboxylate water reducer and the sodium silicate is further promoted, the polycarboxylate water reducer and the sodium silicate are adhered to the waste concrete, and the waste concrete is rapidly covered and infiltrated into the pores and gaps of the waste concrete. In the infiltration process, sodium silicate is promoted to fully react with hydration products in the waste concrete, and calcium silicate colloid is generated to fill pores and gaps, so that the density and strength of the waste concrete are improved; in addition, the holes and gaps are filled, so that the required water absorption amount of the waste concrete in the preparation of the recycled concrete can be effectively reduced, and the slump is improved. Under the cooperation of special proportion, the side chain of polycarboxylate water reducer combines with the calcium silicate of production to form special stable structure, promote polycarboxylate water reducer to adsorb the waste concrete surface, further strengthened the stability of filling hole, gap, be difficult for droing.
When the sodium silicate is in subsequent reaction contact with cement, the sodium silicate can further react with the cement to generate a wrapper to strengthen the blocking effect, so that the structure and the strength of the waste concrete are further improved.
The waste concrete is modified, so that the surface structure is changed, and the problems of low strength and poor fluidity are effectively solved when the waste concrete is used for preparing the recycled concrete, and the strength and the slump of the recycled concrete are greatly improved.
Preferably, the weight ratio of the polyethylene glycol, the polycarboxylate water reducer and the sodium silicate is (1.2-3.0): (3.0-4.5): (5.5-7.0).
When the amount of sodium silicate is too large, the resulting structure may overcoated the waste concrete surface, causing the roughness of the waste concrete surface to decrease, thereby affecting the subsequent engagement with the cement.
By adopting the technical scheme, the usage amount among the three materials is further limited, so that the effect of well filling the pores can be achieved, and the occurrence of excessive coating can be reduced.
Preferably, the preparation of the modified waste concrete comprises the following steps:
crushing and screening to obtain concrete to be treated;
uniformly mixing water, polyethylene glycol, a polycarboxylate water reducer and sodium silicate to obtain a standby liquid;
mixing the standby liquid with the concrete to be treated, stirring, and standing and soaking for 2-3.5h;
and (3) solid-liquid separation and drying of the solid to obtain the modified waste concrete.
By adopting the technical scheme, the waste concrete is mixed with polyethylene glycol, the polycarboxylate water reducer and sodium silicate in a soaking way, so that a good environment is provided for the polyethylene glycol, the polycarboxylate water reducer and the sodium silicate to enter, infiltrate gaps and pores, and the pores of the waste concrete are uniformly filled, so that the structure and performance of the waste concrete are improved.
Preferably, when the standby liquid and the concrete to be treated are mixed and stirred, stirring is carried out under the conditions of 80-90 ℃ and 250-350 r/min; and when the mixture is placed for soaking, the temperature is kept at 50-65 ℃.
By adopting the technical scheme, the rotating speed and the temperature during soaking the waste concrete are further limited, so that polyethylene glycol, a polycarboxylate water reducing agent, sodium silicate and the surface and pores of the waste concrete are more fully combined and reacted.
Preferably, the particle size of the modified waste concrete is 1.5-3.0mm.
Preferably, the fiber is one or more of brucite fiber, sodium carboxymethyl cellulose, carbon fiber and steel fiber.
By adopting the technical scheme, the specific type of fiber is selected to be put into the recycled concrete for preparation, which is favorable for forming a network structure to strengthen the bonding strength between the waste concrete and the cement, thereby improving the compressive strength and the tensile strength of the recycled concrete.
Preferably, the fibers are brucite fibers and sodium carboxymethyl cellulose, and the weight ratio of the brucite fibers to the sodium carboxymethyl cellulose is 1: (0.1-0.4).
By adopting the technical scheme, the types and the proportions of the fibers are further limited, and the sodium carboxymethyl cellulose reacts with groups on the surface of brucite fibers to generate hydrogen bonds, so that the fiber is favorable for uniform dispersion and forms a special network structure.
When the modified waste concrete is mixed with the special network structure, the charges on the surfaces of the modified waste concrete and brucite fibers tend to attract each other, so that the modified waste concrete can be anchored on the special network structure, and can be uniformly distributed in the system while still maintaining a relatively stable state, thereby ensuring that the performance of the recycled concrete is more stable and has a long-lasting effect.
In a second aspect, the present application provides a method for preparing recycled concrete from waste concrete, which adopts the following technical scheme:
the preparation method of the recycled concrete prepared by taking the waste concrete as the raw material comprises the following steps:
mixing water, cement, fiber and admixture to obtain a primary mixed material;
and uniformly mixing the primary mixed material with coarse aggregate and modified waste concrete to obtain a finished product.
In summary, the present application has the following beneficial effects:
1. under the joint coordination of polyethylene glycol, polycarboxylate water reducer and sodium silicate, the infiltration of the polycarboxylate water reducer and the sodium silicate is further promoted, the polycarboxylate water reducer and the sodium silicate are adhered to the waste concrete, and the waste concrete is rapidly covered and infiltrated into the pores and gaps of the waste concrete. In the infiltration process, sodium silicate is promoted to fully react with hydration products in the waste concrete, and calcium silicate colloid is generated to fill pores and gaps, so that the density and strength of the waste concrete are improved.
2. Under the cooperation of special proportion, the side chain of polycarboxylate water reducer combines with the calcium silicate of production to form special stable structure, promote polycarboxylate water reducer to adsorb the waste concrete surface, further strengthened the stability of filling hole, gap, be difficult for droing.
3. The waste concrete is modified, so that the surface structure is changed, and the problems of low strength and poor fluidity are effectively solved when the waste concrete is used for preparing the recycled concrete, and the strength and the slump of the recycled concrete are greatly improved.
Detailed Description
The present application is described in further detail below with reference to examples.
The raw materials used in the following examples and comparative examples are all commercially available products.
Preparation example
Preparation example 1
The modified waste concrete comprises the following raw materials: 450kg of water, 1.8kg of polyethylene glycol, 100kg of waste concrete, 4kg of polycarboxylate water reducer and 7kg of sodium silicate.
The preparation example also discloses a preparation method of the modified waste concrete, which comprises the following steps:
step 1): and selecting, crushing and screening the waste concrete to obtain the concrete to be treated with the particle size of 2.0 mm.
Step 2): adding water into a stirrer, then sequentially adding polyethylene glycol, a polycarboxylate water reducer and sodium silicate into the water, stirring while adding, and mixing until uniformity is achieved, thus obtaining the standby liquid.
Step 3): and (3) putting the concrete to be treated into a reaction kettle, and then adding the standby liquid while stirring, wherein the standby liquid is added in four parts, and the intervals between the parts are 3min. Mixing the standby liquid and the concrete to be treated at the temperature of 85 ℃ and the speed of 300 r/min.
After stirring evenly, the temperature is reduced to 60 ℃, and the mixture is kept stand and soaked for 3 hours.
Step 4): and 3) carrying out solid-liquid separation on the mixture obtained in the step 3), airing the solid, and further sieving to ensure that the particle size is 1.5-3.0mm, thus obtaining the modified waste concrete.
Preparation example 2
The modified waste concrete is different from the preparation example 1 in that the weight ratio of polyethylene glycol, polycarboxylate water reducer and sodium silicate is 1.2:4.5:7.0, namely, the using amount of polyethylene glycol is 1.2kg, the using amount of polycarboxylate water reducer is 4.5kg, and the using amount of sodium silicate is 7.1kg.
Preparation example 3
The modified waste concrete is different from the preparation example 1 in that the weight ratio of polyethylene glycol, polycarboxylate water reducer and sodium silicate is 3.0:3.0:5.5, namely, the using amount of polyethylene glycol is 3.3kg, the using amount of polycarboxylate water reducer is 3.3kg, and the using amount of sodium silicate is 6.2kg.
Preparation example 4
A preparation method of modified waste concrete is different from preparation example 1 in that in step 3), the standby liquid and the concrete to be treated are stirred under the conditions of normal temperature and 25 r/min; stirring uniformly, and standing and soaking at normal temperature.
Preparation example 5
The modified waste concrete was different from preparation example 1 in that the amount of water used was 500kg, the amount of polyethylene glycol used was 5kg, the amount of waste concrete used was 110kg, the amount of polycarboxylate water reducer used was 4.5kg, and the amount of sodium silicate used was 7.5kg.
The preparation method of the modified waste concrete is different from that of the preparation example 1 in that:
in the step 3), stirring the standby liquid and the concrete to be treated at 80 ℃ and 350 r/min; after stirring evenly, standing and soaking for 3.5h at 50 ℃.
Preparation example 6
The modified waste concrete was different from preparation example 1 in that the amount of water used was 400kg, the amount of polyethylene glycol used was 1kg, the amount of waste concrete used was 90kg, the amount of polycarboxylate water reducer used was 1.8kg, and the amount of sodium silicate used was 3.6kg.
The preparation method of the modified waste concrete is different from that of the preparation example 1 in that:
in the step 3), stirring the standby liquid and the concrete to be treated at 90 ℃ and 250 r/min; after stirring evenly, standing and soaking for 2 hours at 65 ℃.
Preparation example 7
The modified waste concrete was different from preparation example 1 in that polyethylene glycol was replaced with water, i.e., the amount of polyethylene glycol used was 0kg and the amount of water used was 451.8kg.
Preparation example 8
The modified waste concrete was different from preparation example 1 in that the polycarboxylate water reducer was replaced with a naphthalene-based superplasticizer, namely, the amount of polycarboxylate water reducer used was 0kg, and the amount of naphthalene-based superplasticizer used was 4kg.
Preparation example 9
The modified waste concrete was different from preparation example 1 in that sodium silicate was replaced with silica, that is, the amount of sodium silicate used was 0kg and the amount of silica used was 7kg.
Preparation example 10
The modified waste concrete was different from preparation example 1 in that the amount of polyethylene glycol used was 9kg, the amount of polycarboxylate water reducer used was 1kg, and the amount of sodium silicate used was 2.8kg.
Examples
Example 1
The regenerated concrete prepared by taking waste concrete as a raw material comprises the following raw materials: 75kg of water, 380kg of modified waste concrete, 550kg of coarse aggregate, 10kg of admixture, 450kg of cement and 10kg of fiber.
The modified waste concrete was the modified waste concrete produced in preparation example 1.
The coarse aggregate is crushed stone with the particle size of 10-15 mm.
The admixture is fly ash.
The cement was portland cement with PO 42.5.
The fibers are brucite fibers and sodium carboxymethyl cellulose, and the weight ratio of the brucite fibers to the sodium carboxymethyl cellulose is 1:0.2, i.e. brucite fibre 1.7kg and sodium carboxymethylcellulose 8.3kg.
The embodiment of the application also discloses a preparation method of the recycled concrete prepared by taking the waste concrete as a raw material, which comprises the following steps:
step a): mixing cement, fiber and admixture, then adding water and stirring until uniform to obtain a primary mixed material.
Step b): and uniformly mixing the coarse aggregate and the modified waste concrete, and then adding the primary mixed material, stirring and mixing to obtain a finished product.
Example 2
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 2.
Example 3
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 3.
Example 4
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 4.
Example 5
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 5.
Example 6
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 6.
Example 7
The regenerated concrete prepared from the waste concrete is different from the embodiment 1 in that the fibers are brucite fibers and sodium carboxymethyl cellulose, and the weight ratio of the brucite fibers to the sodium carboxymethyl cellulose is 1:1, i.e. brucite fibre, has a weight of 5kg and sodium carboxymethylcellulose has a weight of 5kg.
Example 8
The regenerated concrete prepared from the waste concrete was different from example 1 in that the fibers were brucite fibers, i.e., the weight of brucite fibers was 10kg, and the weight of sodium carboxymethylcellulose was 0kg.
Example 9
The regenerated concrete prepared from the waste concrete was different from example 1 in that the amount of water used was 70kg, the amount of modified waste concrete used was 350kg, the amount of coarse aggregate used was 550kg, the amount of admixture used was 20kg, the amount of cement used was 145kg, and the amount of fiber used was 5kg.
The fibers are brucite fibers and sodium carboxymethyl cellulose, and the weight ratio of the brucite fibers to the sodium carboxymethyl cellulose is 1:0.1, i.e. brucite fibre, weight 0.5kg and sodium carboxymethylcellulose weight 4.5kg.
Example 10
The regenerated concrete prepared from the waste concrete was different from example 1 in that the amount of water used was 80kg, the amount of modified waste concrete used was 400kg, the amount of coarse aggregate used was 500kg, the amount of admixture used was 5kg, the amount of cement used was 155kg, and the amount of fiber used was 20kg.
The fibers are brucite fibers and sodium carboxymethyl cellulose, and the weight ratio of the brucite fibers to the sodium carboxymethyl cellulose is 1:0.4, i.e. brucite fibre, weight 5.7kg and sodium carboxymethylcellulose weight 14.3kg.
Comparative example
Comparative example 1
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 7.
Comparative example 2
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 8.
Comparative example 3
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 9.
Comparative example 4
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was the modified waste concrete prepared in preparation example 10.
Comparative example 5
The regenerated concrete prepared from the waste concrete was different from example 1 in that the modified waste concrete was replaced with river sand, i.e., the amount of the modified waste concrete used was 0kg and the amount of the river sand used was 380kg.
Performance test
1. Compressive strength: the compressive strength of the products of examples 1-11 and comparative examples 1-5 were tested according to GB/T50081-2019 Standard of test methods for physical mechanical Properties of concrete.
2. Tensile strength: the products of examples 1-11 and comparative examples 1-5 were tested for split tensile strength according to GB/T50081-2019 Standard of test methods for physical mechanical Properties of concrete.
3. Fluidity: the products of examples 1-11 and comparative examples 1-5 were filled with a trumpet-shaped slump barrel with an upper opening of 100mm, a lower opening of 200mm and a height of 300mm, respectively, and each product was filled three times, and after each filling, a ram was used to uniformly hit 25 down the barrel wall from outside to inside, and the barrel was smoothed. Then the barrel is pulled up, the height of the highest point of the concrete after the collapse is subtracted by the height of the barrel (300 mm), and the obtained difference value is the slump. The slump is large and the fluidity is good.
4. Apparent density: the products of examples 1-11 and comparative examples 1-5 were tested for compactness according to GB/T50081-2019 Standard of test methods for physical mechanical Properties of concrete.
The results of the above tests 1-4 are detailed in Table 1.
TABLE 1
As can be seen from comparison of the test data of examples 1-3 with comparative examples 1-3 in Table 1, the concrete products prepared in comparative examples 1-3 were inferior in compressive strength, tensile strength, fluidity and apparent density to those of example 1 in the absence of one of polyethylene glycol, polycarboxylate water reducer and sodium silicate. In combination with the test data of comparative example 4, even though polyethylene glycol, a polycarboxylate water reducing agent and sodium silicate were used, the three were not blended at a specific use ratio, and the prepared concrete product was slightly better than comparative examples 1 to 3, but far inferior to example 1. The modification of the waste concrete is described, and polyethylene glycol, a polycarboxylate water reducer and sodium silicate are required to be specifically mixed in a specific proportion to effectively improve the structure of the waste concrete.
By combining the detection results of comparative example 5, it is known that the concrete product (example 1) prepared by the most preferable scheme of the technical scheme of the application has similar compression resistance, fracture resistance, fluidity and apparent density to those of comparative example 5 (namely, the product prepared by using river sand instead of waste concrete), and even slightly better than that of example 1. The modified waste concrete is used as fine aggregate to be put into recycled concrete, so that the effect similar to that of river sand can be achieved, and the problems caused by conventional waste concrete are effectively relieved.
From comparison of the test results of example 1 and example 4 in table 1, it is understood that when the treatment conditions (soaking temperature, stirring speed, etc.) of the concrete to be treated in step 3) are changed, the uniformity of the polyethylene glycol, the polycarboxylate water reducer, and the sodium silicate covering the surface of the waste concrete and the pores is affected, thereby affecting the structure of the modified waste concrete.
From comparison of the test results of example 1 and examples 7 and 8 in table 1, it is understood that the modified waste concrete can be attracted to each other and its performance in the system can be improved, thereby improving the performance of the recycled concrete, when the fibers are brucite fibers and sodium carboxymethyl cellulose and are blended in a specific ratio under the same condition as the modified waste concrete. When the mixing proportion between brucite fiber and sodium carboxymethyl cellulose is changed, the mixing effect with modified waste concrete is slightly reduced; after the coordination between brucite fiber and sodium carboxymethyl cellulose is destroyed, the coordination effect with modified waste concrete is obviously reduced.
The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.
Claims (8)
1. The regenerated concrete prepared from the waste concrete is characterized by comprising the following raw materials in parts by weight: 70-80 parts of water, 350-400 parts of modified waste concrete, 500-550 parts of coarse aggregate, 0-20 parts of admixture, 145-155 parts of cement and 0-20 parts of fiber;
the modified waste concrete comprises the following preparation raw materials: 400-500 parts of water, 1-5 parts of polyethylene glycol, 90-110 parts of waste concrete, 1.8-4.5 parts of polycarboxylate water reducer and 3.6-7.5 parts of sodium silicate.
2. The recycled concrete prepared from waste concrete as claimed in claim 1, wherein: the weight ratio of the polyethylene glycol to the polycarboxylate water reducer to the sodium silicate is (1.2-3.0): (3.0-4.5): (5.5-7.0).
3. The recycled concrete prepared from waste concrete as claimed in claim 1, wherein: the preparation of the modified waste concrete comprises the following steps:
crushing and screening to obtain concrete to be treated;
uniformly mixing water, polyethylene glycol, a polycarboxylate water reducer and sodium silicate to obtain a standby liquid;
mixing the standby liquid with the concrete to be treated, stirring, and standing and soaking for 2-3.5h;
and (3) solid-liquid separation and drying of the solid to obtain the modified waste concrete.
4. The recycled concrete prepared from waste concrete as claimed in claim 3, wherein: when the standby liquid and the concrete to be treated are mixed and stirred, stirring is carried out under the conditions of 80-90 ℃ and 250-350 r/min; and when the mixture is placed for soaking, the temperature is kept at 50-65 ℃.
5. The recycled concrete prepared from waste concrete as claimed in claim 3, wherein: the particle size of the modified waste concrete is 1.5-3.0mm.
6. The recycled concrete prepared from waste concrete as claimed in claim 1, wherein: the fiber is one or more of brucite fiber, sodium carboxymethyl cellulose, carbon fiber and steel fiber.
7. The recycled concrete prepared from waste concrete as claimed in claim 6, wherein: the fiber is brucite fiber and sodium carboxymethyl cellulose, and the weight ratio of the brucite fiber to the sodium carboxymethyl cellulose is 1: (0.1-0.4).
8. A method for preparing recycled concrete prepared from waste concrete according to any one of claims 1 to 7, comprising the steps of:
mixing water, cement, fiber and admixture to obtain a primary mixed material;
and uniformly mixing the primary mixed material with coarse aggregate and modified waste concrete to obtain a finished product.
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| CN202310516997.5A CN116535164A (en) | 2023-05-09 | 2023-05-09 | Recycled concrete prepared from waste concrete as raw material and preparation method thereof |
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| CN202310516997.5A CN116535164A (en) | 2023-05-09 | 2023-05-09 | Recycled concrete prepared from waste concrete as raw material and preparation method thereof |
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