Super slow-setting concrete and preparation method thereof

Abstract

The present application relates to a super slow setting concrete and a preparation method thereof, and relates to the field of building materials, which includes the following components by mass: 300-350 parts of cement, 800-1000 parts of coarse aggregate, 600-800 parts of fine aggregate, 40-60 parts of composite retarder, 4-8 parts of slow setting water reducer, 200-300 parts of filler and 150-200 parts of water; the composite retarder includes a polymer retarder and a bio-based colloidal retarder. The preparation method includes the following steps: mixing cement, coarse aggregate, fine aggregate and filler, stirring to obtain a dry mix; adding water accounting for 70-90% of the total amount to the dry mix, stirring to obtain a premix; adding a composite retarder and a water reducer to the remaining water, stirring to obtain a mixed solution; adding the mixed solution to the premix, stirring to obtain super slow setting concrete. The present application has the effect of improving the slow setting performance of concrete, the initial setting time of concrete is long, can meet the needs of special construction, and has high compressive strength and good durability after hardening.

Description

Technical Field

[0001] The present application relates to the technical field of building materials, and in particular to a super slow-setting concrete and a preparation method thereof. Background Art

[0002] With the advancement of urbanization in my country, super-high, super-deep and super-large-scale construction projects continue to emerge, which also puts forward higher requirements for concrete technology. In the construction of bored interlocking piles for deep foundation pit maintenance structures such as subways and stations, the initial setting time of concrete is required to reach more than 60 hours, and there must be sufficient later strength, so the technical requirements for super-slow setting concrete are proposed. Super-slow setting concrete is a new type of concrete specially configured to meet special construction requirements, with an initial setting time of 60-80 hours and a 28d strength not lower than the design strength grade.

[0003] The development and application of super slow-setting concrete can meet the diversification of concrete construction technology. Although the existing slow-setting concrete can extend the setting time to a certain extent, it still faces problems such as insufficient initial setting time and poor stability. Especially in high temperature environment, the initial setting time of concrete will be significantly shortened, making it difficult to control during the construction process, so it needs to be improved. Summary of the invention

[0004] In order to improve the slow-setting performance of concrete, the present application provides a super slow-setting concrete and a preparation method thereof.

[0005] The present application provides a super slow setting concrete and a preparation method thereof using the following technical solutions: In the first aspect, the present application provides a super slow setting concrete, which adopts the following technical solution: A super slow-setting concrete comprising the following components in parts by mass: 300-350 parts of cement Coarse aggregate 800-1000 parts Fine aggregate 600-800 parts Composite retarder 40-60 parts 4-8 parts of slow setting water reducing agent Filler 200-300 parts 150-200 parts of water; The composite retarder comprises a polymer retarder and a bio-based colloidal retarder.

[0006] The polymer retarder and bio-based colloidal retarder in the composite retarder work together to effectively extend the setting time of concrete. The polymer retarder contains a variety of functional groups on its molecular chain, which can interact with the ions or active sites on the surface of cement particles to form a protective film, hindering the contact between cement particles and water, slowing down the hydration rate of cement, and extending the setting time of cement; the bio-based colloidal retarder can fill the gaps between cement particles, change the microstructure of cement paste, limit the contact and reaction between cement particles, and at the same time, the active ingredients in the colloid react with cement hydration products to delay further hydration of cement; the polymer retarder and the bio-based The colloidal retarder works synergistically to promote the dispersion of cement particles and provide more adsorption sites for the composite retarder. The composite retarder further stabilizes the dispersion state, more accurately regulates the hydration rate of cement, and effectively prolongs the initial and final setting times. The retarding water reducer achieves a dispersion effect by adsorbing on the surface of cement particles to give them the same charge, which not only reduces the water-cement ratio to ensure workability, but also affects the hydration process of cement due to the retarding components therein. The retarding water reducer and the composite retarder work synergistically to reduce the hydration rate of cement, significantly prolong the setting time of concrete, and at the same time optimize the internal structure of concrete, enhance cohesion and water retention, reduce segregation and water bleeding, and improve the strength and durability of concrete.

[0007] Preferably, the raw materials for preparing the polymer retarder include citric acid, triethanolamine and methoxy polyethylene glycol methacrylate.

[0008] The carboxyl group of citric acid reacts with the hydroxyl group of triethanolamine to form an esterification reaction, and the product can form a physical adsorption layer on the surface of cement particles, which hinders the contact between cement particles and water; the esterification reaction product generated by citric acid and triethanolamine polymerizes with methoxy polyethylene glycol methacrylate to generate a molecule with a three-dimensional branched structure, which contains rich terminal functional groups. These functional groups can complex with ions in the cement hydration process, reduce the ion concentration in the liquid phase, and delay the formation of cement hydration products, thereby effectively extending the initial and final setting times of concrete; the retarding effect makes the cement hydration process more sufficient and uniform, and the hydration products can better fill the internal pores of the concrete to form a denser microstructure. The three-dimensional branched structure also plays a reinforcing role, effectively improving the compressive strength of the concrete; the polymer retarder can enhance the water retention of concrete, reduce the appearance of shrinkage cracks caused by excessive water loss, limit the development of shrinkage stress caused by water evaporation in the concrete, maintain the stability of the concrete, and thus improve the durability of the concrete.

[0009] Preferably, the mass ratio of the citric acid, triethanolamine and methoxy polyethylene glycol methacrylate is 1:1:(0.6-0.8).

[0010] The polymer retarder prepared according to the above mass ratio has good retarding performance and can improve the compressive strength and durability of concrete.

[0011] Preferably, the raw materials for preparing the bio-based colloidal retarder include bio-based waste, alkali and maleic anhydride.

[0012] Alkali can destroy the internal structure of bio-based waste, release its active ingredients, and increase the active groups on the surface of the waste; maleic anhydride reacts with these active ingredients and active groups to generate colloids with retarding function. These colloids can be adsorbed on the surface of cement particles to form a protective film, hindering the contact between cement and water, slowing down the hydration reaction rate, and thus prolonging the setting time of concrete; bio-based colloidal retarders can also fill in the gaps between cement particles, improve the microstructure of concrete, enhance the cohesion of concrete, reduce water seepage and segregation, and make the concrete structure denser, thereby improving the compressive strength and durability of concrete, effectively resisting the erosion of concrete by external environmental factors, and further improving the overall performance of concrete.

[0013] Preferably, the bio-based waste includes waste penicillin residue and waste Aspergillus niger residue.

[0014] Penicillin waste residue and Aspergillus niger waste residue have rich active groups, such as proteins, polysaccharides and other components, which can be activated and react with maleic anhydride to form a colloid with a retarding effect, hinder the process of hydration reaction, fill and optimize the internal structure of concrete, thereby improving the durability and compressive strength of concrete.

[0015] Preferably, the bio-based retarder is prepared by the following steps: Pre-treating the waste penicillin residue and the waste Aspergillus niger residue, performing preliminary screening, drying, and then crushing, washing with water, and then drying to obtain pre-treated bio-based waste; The pretreated bio-based waste, alkali and water are mixed, heated and stirred for reaction, and maleic anhydride is added after cooling, and stirred while adding. After the addition is completed, the temperature is raised and stirred for reaction, and the material is discharged after cooling to obtain a bio-based colloidal retarder.

[0016] The bio-based colloidal retarder prepared according to the above steps has good retarding performance and can effectively improve the compressive strength and durability of concrete.

[0017] Preferably, the retarding water reducer includes a naphthalene-based retarding high-efficiency water reducer and a polycarboxylic acid high-performance retarding water reducer.

[0018] Naphthalene-based slow-setting high-efficiency water-reducing agent contains functional groups such as sulfonic acid groups. Sulfonic acid groups can be adsorbed on the surface of cement particles, making cement particles carry the same charge and generate electrostatic repulsion, thereby dispersing cement particles and reducing agglomeration. The fluidity of concrete can be improved while reducing the water-cement ratio. Its slow-setting components can react with calcium ions in cement, delay the formation of hydration products such as ettringite, and prolong the setting time. Polycarboxylic acid high-performance slow-setting water-reducing agent has a unique comb-like molecular structure. Strong polar groups such as carboxyl groups on the main chain are adsorbed on cement particles, and side chains form steric hindrance around cement particles, further enhancing the dispersion effect of cement particles. At the same time, it effectively controls the hydration rate of cement, so that concrete maintains good fluidity, cohesion and water retention for a long time, reduces segregation and bleeding, and allows cement hydration reaction to proceed more fully and evenly during the hardening process, making the concrete structure denser and improving compressive strength and durability.

[0019] Preferably, the filler comprises fly ash and slag, and the mass ratio of the fly ash to the slag is (2-3):1.

[0020] Fly ash contains a large number of glass beads, which have a rolling effect and can improve the fluidity of concrete. The volcanic ash activity can react with the cement hydration product calcium hydroxide to produce more gel, which fills the internal pores of concrete, makes the concrete structure denser, and enhances the strength and durability of concrete. Slag contains aluminosilicate components, which can participate in the hydration reaction of cement in an alkaline environment and further improve the later strength of concrete. By compounding according to the above-mentioned mass ratio, slag and fly ash can complement each other, optimize the particle grading of concrete, improve the microstructure of concrete, reduce porosity, and not only improve the workability of concrete, but also enhance its strength and durability.

[0021] Preferably, the fly ash and slag are modified to obtain a modified slow-setting filler, and the modified slow-setting filler is prepared by the following steps: The fly ash and slag are sorted and ground to obtain pretreated fly ash and pretreated slag; the pretreated fly ash and pretreated slag are mixed and dispersed in a water glass solution, heated and stirred for reaction, and discharged after cooling to obtain a modified slow-setting filler.

[0022] By sorting and grinding fly ash and slag to increase the specific surface area, the pretreated fly ash and slag are mixed and dispersed in a water glass solution. The silicate ions in the water glass will react with the active components on the surface of the fly ash and slag to form a gel film with a retarding effect on the surface of the fly ash and slag. This gel film can be adsorbed on the surface of cement particles, hindering the rapid contact between cement particles and water, slowing down the cement hydration rate, and thus prolonging the setting time of concrete; water glass can also enhance the volcanic ash activity of fly ash and slag, so that their secondary hydration reaction with the cement hydration product calcium hydroxide during the concrete hardening process is more complete, and the generated gel product can more effectively fill the internal pores of the concrete, optimize the pore structure, reduce harmful pores, and increase the density of the concrete, thereby improving the compressive strength and durability of the concrete.

[0023] In a second aspect, the present application provides a method for preparing super slow-setting concrete, which adopts the following technical solution: A method for preparing super slow-setting concrete comprises the following steps: Cement, coarse aggregate, fine aggregate and filler are mixed and stirred to obtain a dry mix; water accounting for 70-90% of the total amount is added to the dry mix, and the mixture is stirred to obtain a premix; a composite retarder and a water reducing agent are added to the remaining water, and the mixture is stirred to obtain a mixed liquid; the mixed liquid is added to the premix, and the mixture is stirred to obtain a super-retarded concrete.

[0024] The concrete prepared according to the above steps has good retarding properties, can meet the needs of special construction, maintains good fluidity, can be fully hydrated, and has good compressive strength and durability.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. The polymer retarder and bio-based colloidal retarder in the composite retarder work together to effectively extend the setting time of concrete. The polymer retarder contains a variety of functional groups on its molecular chain, which can interact with the ions or active sites on the surface of cement particles to form a protective film, hindering the contact between cement particles and water, slowing down the hydration rate of cement, and extending the setting time of cement; the bio-based colloidal retarder can fill the gaps between cement particles, change the microstructure of cement paste, limit the contact and reaction between cement particles, and at the same time, the active ingredients in the colloid react with cement hydration products to delay further hydration of cement; polymer retarders and bio-based colloidal retarders can effectively extend the setting time of concrete. The synergistic effect of the base colloidal retarder promotes the dispersion of cement particles and provides more adsorption sites for the composite retarder. The composite retarder further stabilizes the dispersion state, more accurately regulates the hydration rate of cement, and effectively prolongs the initial and final setting times. The retarding water reducer achieves a dispersion effect by adsorbing on the surface of cement particles to give them the same charge, which not only reduces the water-cement ratio to ensure workability, but also affects the hydration process of cement due to the retarding components therein. The retarding water reducer and the composite retarder work synergistically to reduce the hydration rate of cement, significantly prolong the setting time of concrete, and at the same time optimize the internal structure of concrete, enhance cohesion and water retention, reduce segregation and water bleeding, and improve the strength and durability of concrete.

[0026] 2. The carboxyl group of citric acid reacts with the hydroxyl group of triethanolamine to form an esterification reaction, and the product can form a physical adsorption layer on the surface of cement particles, which hinders the contact between cement particles and water; the esterification reaction product generated by citric acid and triethanolamine polymerizes with methoxy polyethylene glycol methacrylate to generate a molecule with a three-dimensional branched structure, which contains rich terminal functional groups. These functional groups can complex with ions in the cement hydration process, reduce the ion concentration in the liquid phase, and delay the formation of cement hydration products, thereby effectively extending the initial and final setting time of concrete; the retarding effect makes the cement hydration process more sufficient and uniform, and the hydration products can better fill the internal pores of the concrete to form a denser microstructure. The three-dimensional branched structure also plays a reinforcing role, effectively improving the compressive strength of the concrete; the polymer retarder can enhance the water retention of concrete, reduce the appearance of shrinkage cracks caused by excessive water loss, limit the development of shrinkage stress caused by water evaporation in the concrete, maintain the stability of the concrete, and thus improve the durability of the concrete.

[0027] 3. Alkali can destroy the internal structure of bio-based waste, release its active ingredients, and increase the active groups on the surface of the waste; maleic anhydride reacts with these active ingredients and active groups to generate colloids with retarding function. These colloids can be adsorbed on the surface of cement particles to form a protective film, hindering the contact between cement and water, slowing down the hydration reaction rate, and thus prolonging the setting time of concrete; bio-based colloidal retarders can also fill in the gaps between cement particles, improve the microstructure of concrete, enhance the cohesion of concrete, reduce water seepage and segregation, and make the concrete structure denser, thereby improving the compressive strength and durability of concrete, effectively resisting the erosion of concrete by external environmental factors, and further improving the overall performance of concrete. DETAILED DESCRIPTION

[0028] The present application discloses an ultra-slow setting concrete and a preparation method thereof. The raw materials used in the present application can be obtained from commercially available raw materials unless otherwise specified. The present application is further described in detail below in conjunction with the embodiments: Raw materials description: citric acid (CAS No.: 77-92-9), triethanolamine (CAS No.: 102-71-6), methoxy polyethylene glycol methacrylate (CAS No.: 26915-72-0), azobisisobutyronitrile (CAS No.: 78-67-1), penicillin waste residue was collected from Suzhou Erye Pharmaceutical Co., Ltd., Aspergillus niger waste residue was collected from Suzhou Renpin Chemical Technology Co., Ltd., alkali is sodium hydroxide, maleic anhydride (CAS No.: 108-31-6), water glass (CAS No.: 1344-09-8), cement is Portland cement P.O42.5, coarse aggregate is 5-20mm continuously graded crushed stone, fine aggregate is river sand with fineness modulus 2.3, mud content is 2%, fly ash is Class II fly ash, fineness is 15%, water requirement ratio is 95%, loss on ignition is 2%, slag model is S95, polycarboxylic acid high-performance retarding water reducer model is ZY-SR, purchased from Hunan Zhongyan Building Materials Technology Co., Ltd., naphthalene-based retarding high-efficiency water reducer model is DC-WR2, purchased from Beijing Dechang Weiye Construction Engineering Technology Co., Ltd., and polycarboxylic acid high-efficiency water reducer model is ZK-PCA.

[0029] Preparation Example 1 Preparation of polymer retarder 7.69 kg of citric acid and 7.69 kg of triethanolamine were mixed, stirred at a speed of 300 rpm, slowly heated to 120°C at a speed of 5°C / min, and water was removed through a condenser. After reacting for 6 hours, a preliminary product was obtained; the preliminary product was cooled to 80°C, 4.62 kg of methoxypolyethylene glycol methacrylate was added, and stirred at a speed of 300 rpm during the addition, and the addition was completed within 1 hour, 0.1 kg of azobisisobutyronitrile was added, and the mixture was stirred at a speed of 300 rpm at 80°C for 4 hours, and small molecular substances were removed by reduced pressure distillation to obtain a hyperbranched polyester.

[0030] Preparation Example 2 Preparation Example 2 is based on Preparation Example 1. The only difference between Preparation Example 2 and Preparation Example 1 is that the amount of citric acid used in Preparation Example 2 is 7.14 kg, the amount of triethanolamine used is 7.14 kg, and the amount of methoxy polyethylene glycol methacrylate used is 5.72 kg.

[0031] Preparation Example 3 Preparation Example 3 is based on Preparation Example 1. The only difference between Preparation Example 3 and Preparation Example 1 is that the amount of citric acid used in Preparation Example 3 is 7.41 kg, the amount of triethanolamine used is 7.41 kg, and the amount of methoxy polyethylene glycol methacrylate used is 5.18 kg.

[0032] Preparation Example 4 Preparation Example 4 is based on Preparation Example 1. The only difference between Preparation Example 4 and Preparation Example 1 is that the amount of citric acid used in Preparation Example 4 is 8 kg, the amount of triethanolamine used is 8 kg, and the amount of methoxy polyethylene glycol methacrylate used is 4 kg.

[0033] Preparation Example 5 Preparation Example 5 is based on Preparation Example 1. The only difference between Preparation Example 5 and Preparation Example 1 is that the amount of citric acid used in Preparation Example 5 is 6.9 kg, the amount of triethanolamine used is 6.9 g, and the amount of methoxy polyethylene glycol methacrylate used is 6.2 kg.

[0034] Preparation Example 6 Preparation of Bio-based Colloidal Retarder The waste residues of penicillin and Aspergillus niger were pretreated, initially screened, dried at 60°C to a moisture content of 10%, crushed to a particle size of 0.5 mm, washed with water three times, and dried at 60°C to a moisture content of 10% to obtain pretreated bio-based waste.

[0035] The pretreated bio-based waste, alkali and water are mixed in a mass ratio of 1:0.2:5, the temperature is raised to 70°C, stirred at 200rpm for reaction for 3h, the temperature is lowered to 50°C, maleic anhydride accounting for 20% of the mass content of the bio-based waste is added, and the mixture is stirred at 200rpm. After the addition is completed, the temperature is raised to 80°C and stirred at 200rpm for reaction for 4h. After cooling to 30°C, the material is discharged to obtain a bio-based colloidal retarder.

[0036] Preparation Example 7 Preparation Example 7 is based on Preparation Example 6. The only difference between Preparation Example 7 and Preparation Example 6 is that in Preparation Example 7, waste Aspergillus niger residue is not added to the bio-based waste.

[0037] Preparation Example 8 Preparation of modified slow-setting filler The fly ash and slag are sorted and ground to obtain pretreated fly ash and pretreated slag; the pretreated fly ash and pretreated slag are dispersed in a water glass solution with a mass fraction of 20% at a mass ratio of 2.5:1 and a solid-liquid ratio of 1:0.5, and the mixture is stirred at a speed of 300 rpm at 40°C for 4 hours, and the mixture is discharged after being cooled to 30°C to obtain a modified slow-setting filler.

[0038] Example 1 300kg cement, 800kg coarse aggregate, 600kg fine aggregate and 200kg filler were mixed, the mass ratio of fly ash to slag in the filler was 2:1, and stirred at 80rpm for 5min and at 120rpm for 5min to obtain a dry mix; 70% of water was added to the dry mix, the total amount of water was 150kg, and stirred at 120rpm for 10min to obtain a premix; 40kg of composite retarder and 4kg of retarding water reducer were added to the remaining water, and the composite retarder and slag were added to the remaining water, and the mixture was stirred at 120rpm for 10min. The mass ratio of the polymer retarder to the bio-based colloidal retarder in the composite retarder is 1:5, the polymer retarder is the polymer retarder prepared in Preparation Example 1, the bio-based colloidal retarder is the bio-based colloidal retarder prepared in Preparation Example 6, and the mass ratio of the naphthalene-based retarding high-efficiency water-reducing agent and the polycarboxylic acid high-performance retarding water-reducing agent in the retarding water-reducing agent is 1:5. Stir at a speed of 200 rpm for 5 min to obtain a mixed solution; add the mixed solution to the premix and stir at a speed of 150 rpm for 30 min to obtain super retarded concrete.

[0039] Example 2 350kg cement, 1000kg coarse aggregate, 800kg fine aggregate and 300kg filler were mixed, the mass ratio of fly ash to slag in the filler was 3:1, and stirred at 80rpm for 5min and at 120rpm for 5min to obtain a dry mix; 90% of the total amount of water was added to the dry mix, the total amount of water was 200kg, and stirred at 120rpm for 10min to obtain a premix; 60kg of composite retarder and 8kg of retarder water reducer were added to the remaining water, The mass ratio of the polymer retarder to the bio-based colloidal retarder in the composite retarder is 1:5, the polymer retarder is the polymer retarder prepared in Preparation Example 2, the bio-based colloidal retarder is the bio-based colloidal retarder prepared in Preparation Example 6, and the mass ratio of the naphthalene-based retarding high-efficiency water-reducing agent and the polycarboxylic acid high-performance retarding water-reducing agent in the retarding water-reducing agent is 1:5. Stir at a speed of 200 rpm for 5 min to obtain a mixed solution; add the mixed solution to the premix and stir at a speed of 150 rpm for 30 min to obtain super retarded concrete.

[0040] Example 3 325kg cement, 900kg coarse aggregate, 700kg fine aggregate and 250kg filler were mixed, the mass ratio of fly ash to slag in the filler was 2.5:1, stirred at 80rpm for 5min, and stirred at 120rpm for 5min to obtain a dry mix; 80% of the total amount of water was added to the dry mix, the total amount of water was 175kg, and stirred at 120rpm for 10min to obtain a premix; 50kg of composite retarder and 6kg of retarder water reducer were added to the remaining water, The mass ratio of the polymer retarder to the bio-based colloidal retarder in the composite retarder is 1:5, the polymer retarder is the polymer retarder prepared in Preparation Example 3, the bio-based colloidal retarder is the bio-based colloidal retarder prepared in Preparation Example 6, and the mass ratio of the naphthalene-based retarding high-efficiency water reducer and the polycarboxylic acid high-performance retarding water reducer in the retarding water reducer is 1:5. Stir at a speed of 200 rpm for 5 min to obtain a mixed solution; add the mixed solution to the premix and stir at a speed of 150 rpm for 30 min to obtain super retarded concrete.

[0041] Example 4 Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that in Example 4, the polymer retarder prepared in Preparation Example 3 is replaced by the polymer retarder prepared in Preparation Example 4.

[0042] Example 5 Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that in Example 5, the polymer retarder prepared in Preparation Example 3 is replaced by the polymer retarder prepared in Preparation Example 5.

[0043] Example 6 Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that in Example 6, the bio-based colloidal retarder prepared in Preparation Example 6 is replaced by the bio-based colloidal retarder prepared in Preparation Example 7.

[0044] Example 7 Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that in Example 7, no naphthalene-based retarding high-efficiency water-reducing agent is added to the retarding water-reducing agent.

[0045] Example 8 Example 8 is based on Example 3, and the only difference between Example 8 and Example 3 is that the mass ratio of fly ash to slag in Example 8 is 1:1.

[0046] Example 9 Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that the mass ratio of fly ash to slag in Example 9 is 5:1.

[0047] Example 10 Example 10 is based on Example 3. The only difference between Example 10 and Example 3 is that in Example 10, the filler is replaced by the modified retarding filler prepared in Preparation Example 8.

[0048] Comparative Example 1 Comparative Example 1 is based on Example 3, and the only difference between Comparative Example 1 and Example 3 is that no bio-based colloidal retarder is added in Comparative Example 1.

[0049] Comparative Example 2 Comparative Example 2 is based on Example 3, and the only difference between Comparative Example 2 and Example 3 is that in Comparative Example 2, the retarding water reducer is replaced by a polycarboxylic acid high-efficiency water reducer.

[0050] Performance testing (1) Select GB / T8076-2008 Concrete Admixtures as the standard to test the initial setting time and final setting time of the samples. Each sample is tested three times and the average value is taken after measurement. The results are recorded in Table 1.

[0051] (2) GB / T50080-2016 Test method for performance of ordinary concrete mixtures was selected as the standard to test the initial slump and 28d compressive strength of the samples. Each sample was tested three times and the average value was taken after measurement. The results are recorded in Table 1.

[0052] (3) The GB / T50082-2024 Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete was selected as the standard, and the 28d shrinkage value (10 -6 ), each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.

[0053] Table 1 Test results of concrete retarding properties, compressive strength, slump and durability As shown in Table 1, the initial setting time of Examples 1-3 is greater than 67.5h, the final setting time is greater than 80.0h, the 28d compressive strength is greater than 56.3MPa, the slump is 215-220mm, and the shrinkage value is less than 125*10 -6 It can be seen that the concrete prepared in this application has good retarding properties, fluidity, compressive strength and durability.

[0054] As can be seen from Table 1, the only difference between Examples 4 and 5 and Example 3 is that the polymer retarder is replaced in Examples 4 and 5. Compared with Example 3, the retarding performance, fluidity, compressive strength and durability of Examples 4 and 5 are reduced. This is because the amount of the synthetic component in the polymer retarder is changed, which affects the performance of the polymer retarder, resulting in excessive inhibition of the hydration reaction or insufficient retarding effect, poor fluidity, and further affecting the structural stability of the concrete, resulting in reduced compressive strength and durability.

[0055] It can be seen from Table 1 that the only difference between Example 6 and Example 3 is that in Example 6, the bio-based colloidal retarder prepared in Preparation Example 6 is replaced by the bio-based colloidal retarder prepared in Preparation Example 7. Compared with Example 3, Example 6 has reduced retarding performance, compressive strength and durability; this is because the components of the bio-based waste are reduced, the synergistic effect of the active substances between the two is lacking, the retarding effect is reduced, and the compressive strength and durability are affected.

[0056] As can be seen from Table 1, the only difference between Example 7 and Example 3 is that no naphthalene-based retarding high-efficiency water-reducing agent is added to the retarding water-reducing agent in Example 7. Compared with Example 3, the retarding performance, compressive strength and durability of Example 7 are reduced. This is because the retarding effect is reduced due to the lack of composite synergistic effect, which affects the hydration reaction and further affects the compressive strength and durability.

[0057] It can be seen from Table 1 that the only difference between Examples 8 and 9 and Example 3 is that the mass ratio of fly ash to slag in Example 8 is 1:1, and the mass ratio of fly ash to slag in Example 9 is 5:1. Compared with Example 3, Examples 8 and 9 have reduced retarding performance, compressive strength and durability; this is because adjusting the ratio of the two will affect their synergistic effect, the retarding performance changes, and then affects the hydration of cement, and the compressive strength and durability of the concrete are affected.

[0058] It can be seen from Table 1 that the only difference between Example 10 and Example 3 is that in Example 10, the filler is replaced by the modified retarding filler prepared in Preparation Example 8. Compared with Example 3, Example 10 has improved retarding performance, compressive strength and durability. This is because the filler is modified to improve its retarding performance, adjust the structure of concrete, increase density, and thus improve compressive strength and durability.

[0059] It can be seen from Table 1 that the only difference between Comparative Example 1 and Example 3 is that no bio-based colloidal retarder is added in Comparative Example 1. Compared with Example 3, the retarding performance, compressive strength and durability of Comparative Example 1 are significantly reduced. This is because without adding the bio-based colloidal retarder, the synergistic effect of the components in the system is reduced, thereby reducing the retarding effect, deteriorating the stability of the concrete, and deteriorating the compressive strength and durability.

[0060] It can be seen from Table 1 that the only difference between Comparative Example 2 and Example 3 is that the retarding water-reducing agent in Comparative Example 2 is replaced by a polycarboxylic acid high-efficiency water-reducing agent. Compared with Example 3, the retarding performance, compressive strength and durability of Comparative Example 2 are reduced. This is because the retarding water-reducing agent is replaced by an ordinary water-reducing agent, which lacks a retarding effect, and the synergistic effect of the water-reducing agent and the composite retarder is reduced, which affects the hydration effect, and thus the compressive strength and durability are affected.

[0061] This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. Through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of ​​the present application. The technical scope of the present application is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A super slow setting concrete, characterized in that: The composition includes the following components in parts by weight: 300-350 parts of cement Coarse aggregate 800-1000 parts Fine aggregate 600-800 parts Composite retarder 40-60 parts 4-8 parts of slow setting water reducing agent Filler 200-300 parts 150-200 parts of water; The composite retarder comprises a polymer retarder and a bio-based colloidal retarder.

2. The super slow setting concrete according to claim 1, characterized in that: The raw materials for preparing the polymer retarder include citric acid, triethanolamine and methoxy polyethylene glycol methacrylate.

3. The super slow setting concrete according to claim 2, characterized in that: The mass ratio of the citric acid, triethanolamine and methoxy polyethylene glycol methacrylate is 1:1:(0.6-0.8).

4. The super slow setting concrete according to claim 1, characterized in that: The raw materials for preparing the bio-based colloidal retarder include bio-based waste materials, alkali and maleic anhydride.

5. The super slow setting concrete according to claim 4, characterized in that: The bio-based waste materials include waste penicillin residue and waste Aspergillus niger residue.

6. The super slow setting concrete according to claim 5, characterized in that: The bio-based retarder is prepared by the following steps: Pre-treating the waste penicillin residue and the waste Aspergillus niger residue, performing preliminary screening, drying, and then crushing, washing with water, and then drying to obtain pre-treated bio-based waste; The pretreated bio-based waste, alkali and water are mixed, heated and stirred for reaction, and maleic anhydride is added after cooling, and stirred while adding. After the addition is completed, the temperature is raised and stirred for reaction, and the material is discharged after cooling to obtain a bio-based colloidal retarder.

7. The super slow setting concrete according to claim 1, characterized in that: The retarding water reducer comprises a naphthalene-based retarding high-efficiency water reducer and a polycarboxylic acid high-performance retarding water reducer.

8. The super slow setting concrete according to claim 1, characterized in that: The filler includes fly ash and slag, and the mass ratio of the fly ash to the slag is (2-3):

1.

9. The super slow setting concrete according to claim 8, characterized in that: The fly ash and slag are modified to obtain a modified slow-setting filler, and the modified slow-setting filler is prepared by the following steps: The fly ash and slag are sorted and ground to obtain pretreated fly ash and pretreated slag; the pretreated fly ash and pretreated slag are mixed and dispersed in a water glass solution, heated and stirred for reaction, and discharged after cooling to obtain a modified slow-setting filler.

10. A method for preparing the super slow setting concrete as claimed in any one of claims 1 to 9, characterized in that: The steps include: Cement, coarse aggregate, fine aggregate and filler are mixed and stirred to obtain a dry mix; water accounting for 70-90% of the total amount is added to the dry mix, and the mixture is stirred to obtain a premix; a composite retarder and a water reducing agent are added to the remaining water, and the mixture is stirred to obtain a mixed liquid; the mixed liquid is added to the premix, and the mixture is stirred to obtain a super-retarded concrete.

Images