High-thixotropy self-compacting concrete for building formwork construction and preparation method of high-thixotropy self-compacting concrete

Abstract

The invention discloses high-thixotropy self-compacting concrete for building formwork construction and a preparation method of the high-thixotropy self-compacting concrete, and relates to a concrete material. The invention aims to provide the high-thixotropy self-compacting concrete which can improve the concrete construction efficiency and the structure entity quality of a building formwork and realize the mutual coordination of the workability, the strength grade and the durability of the concrete in the construction process of the building formwork, and the preparation method thereof. The high-thixotropy self-compacting concrete for building formwork construction is prepared from the following components per cubic meter: 500 to 530 kg of a cementing material, 774 to 828 kg of coarse aggregate, 861 to 873 kg of machine-made sand, 0.10 to 0.16 kg of an organic thixotropic modifier, 40 to 60 kg of an inorganic thixotropic modifier, 6.0 to 6.4 kg of an additive and 170 to 180 kg of mixing water, the preparation method comprises the following steps: uniformly mixing the organic thixotropic modifier with the additive to obtain a composite additive; the method comprises the following steps: firstly, adding part of machine-made sand, a binding material, an inorganic thixotropic modifier, water and part of a composite additive, and stirring to prepare mortar; and adding the coarse aggregate, the residual machine-made sand and the composite additive, and fully stirring.

Description

Technical Field

[0001] The invention relates to the technical field of concrete materials, in particular to a high-thixotropic self-compacting concrete used for building formwork construction and a preparation method thereof. Background Art

[0002] With the continuous development of modern construction engineering technology, the application of building formwork construction technology in various complex structures such as low-rise residential buildings, public buildings, factories, and country villas is becoming more and more widespread. Building formwork is a permanent formwork used to prepare concrete walls. It has a filtering function. Its spatial grid structure is composed of two pieces of steel wire mesh. After the internal cavity is filled with concrete, it can form a wall material. No formwork is required in the construction of building formwork, which avoids the contractor's high investment in formwork; during construction, concrete does not need to be vibrated, there is no noise pollution, the construction speed is fast, the site is clean, and labor and machinery costs are reduced. When pouring concrete, a certain proportion of industrial solid waste or construction waste can be added to reduce material costs and is beneficial to environmental protection.

[0003] Since the construction formwork is an unconventional form of formwork with a relatively complex spatial grid structure, the thixotropy of the poured concrete is required to be high. The concrete needs to have good pumping performance to ensure rapid filling in complex structures after pouring, and it also needs to quickly restore viscosity after pouring to prevent the slurry from seeping out of the holes in the formwork.

[0004] Ordinary self-compacting concrete is a high-flowability, high-performance concrete with good filling, fluidity and gap permeability. However, in order to achieve self-compacting properties, self-compacting concrete is often achieved by increasing the slurry content and increasing the slump expansion of concrete. Although it has good fluidity and can fill complex structures without relying on vibration, during formwork construction, concrete is prone to segregation in a static state, causing the slurry to seep out of the holes in the formwork, affecting the density and integrity of the concrete, and thus affecting the quality of the concrete entity structure.

[0005] A Chinese invention patent (Announcement No. CN108715531A) discloses a highly thixotropic 3D printing concrete and its preparation method. Based on one cubic meter of concrete, the weight percentage of each component is: 35-40% cement, 0.1-0.4% polycarboxylic acid water reducer, 0.1-0.4% polypropylene fiber, 1.0-3.0% thixotropic agent for 3D printing concrete, 12.5-14.5% water, and the rest is sand. Although the concrete prepared by this patent has achieved high thixotropy, it does not have self-compacting properties.

[0006] The Chinese invention patent (Announcement No. CN110423074A) discloses a high thixotropic fast-hardening self-compacting concrete and preparation method for the construction of CRTS III type slab track skylights. The weight percentages of each component are: fast-hardening sulphoaluminate cement 100-120 parts, silicate cement 20-40 parts, fly ash 8-15 parts, gypsum 15-40 parts, sand 190-240 parts, stone 185-235 parts, water 30-40 parts, powder water reducer 1-3 parts, thixotropic viscosity modifier 5-10 parts, hardening accelerator 0.1-0.5 parts, retarder 0.1-0.5 parts. The concrete prepared by this patent has both high thixotropy and self-compacting properties, but the fluidity of this concrete is too strong. When used in building formwork construction, the slurry will seep out of the holes in the formwork, affecting the quality of the physical structure. This patent also uses organic and inorganic thixotropic modifiers, but this patent uses a compound of the two modifiers to improve the thixotropy of concrete. This method cannot fully tap the potential of the two modifiers to improve the thixotropy of concrete.

[0007] A Chinese invention patent (Announcement No. CN108892535A) discloses a self-leveling recycled lightweight aggregate concrete for building formwork and its preparation method. The concrete components and weight percentages are: 25-55% cementitious material, 15-40% recycled lightweight aggregate, 1-4% vermiculite powder, 0.2-1.2% thixotropic lubricant, 0.05-0.5% ecological fiber, 0.2-2% physical foaming agent, 0.05-0.2% foam stabilizer, 0.2-1.5% water reducer, 0.03-0.3% anti-segregation agent, and 10-35% water. Although the concrete in this patent meets the construction requirements when casting the building formwork, the strength of the building formwork wall structure cast by this concrete is too low to be used as a solid structure. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a high-thixotropic self-compacting concrete and a preparation method thereof, which can improve the construction efficiency and structural quality of building formwork concrete and achieve the coordination of concrete workability, strength grade and durability during the construction of the building formwork.

[0009] The present invention provides a technical solution, a highly thixotropic self-compacting concrete for building formwork construction, wherein each cubic meter of the highly thixotropic self-compacting concrete comprises the following components:

[0010] Cementitious material: 500-530kg,

[0011] Coarse aggregate: 774~828kg,

[0012] Machine-made sand: 861-873kg,

[0013] Organic thixotropic modifier: 0.10~0.16kg,

[0014] Inorganic thixotropic modifier: 40-60kg,

[0015] Admixture: 6.0~6.4kg,

[0016] Mixing water: 170~180kg.

[0017] The invention discloses a high-thixotropic self-compacting concrete for building formwork construction, wherein the organic thixotropic modifier is a high-molecular polysaccharide and is compounded with an admixture for use.

[0018] The invention discloses a high thixotropic self-compacting concrete for building formwork construction, wherein the organic thixotropic modifier is a mixture of one or more of gellan gum, xanthan gum or carrageenan. Gellan gum is a linear high molecular polysaccharide composed of glucose, glucuronic acid and rhamnose, xanthan gum is a high molecular polysaccharide composed of glucose, mannose and glucuronic acid, and carrageenan is a high molecular polysaccharide composed of galactose and sulfate groups.

[0019] The invention discloses a high-thixotropic self-compacting concrete for building formwork construction, wherein the inorganic thixotropic modifier is a natural silicate mineral and is directly used as a mineral additive.

[0020] The invention discloses a highly thixotropic self-compacting concrete for building formwork construction, wherein the inorganic thixotropic modifier is a mixture of one or more of sepiolite, rectorite or palygorskite. Sepiolite is a fibrous silicate mineral, rectorite is a layered silicate mineral, and palygorskite is a rod-shaped or fibrous silicate mineral.

[0021] The invention discloses a highly thixotropic self-compacting concrete for building formwork construction, wherein the cementitious material is composed of 42.5-grade ordinary Portland cement, S95 mineral powder and Class C II fly ash, wherein:

[0022] The mass percentage of cement in cementitious materials is 55-70%.

[0023] The total mass percentage of mineral powder and fly ash in cementitious materials is 30-45%.

[0024] The ratio of mineral powder to fly ash is 2:5 to 2:3.

[0025] The invention discloses a high thixotropic self-compacting concrete for building formwork construction, wherein the particle size of the coarse aggregate is 5 to 16 mm and the concrete is continuously graded.

[0026] The invention discloses a high thixotropic self-compacting concrete for building formwork construction, wherein the machine-made sand has a particle size of 0.16 mm to 5 mm, a fineness modulus of 2.6 to 3.2, an MB value of less than 1.0, and a stone powder content of 5 to 8%.

[0027] The invention discloses a high thixotropic self-compacting concrete for building formwork construction, wherein the admixture is a polycarboxylic acid high-performance admixture, the water reduction rate is not less than 25%, and the solid content is 15%.

[0028] The invention discloses a high thixotropic self-compacting concrete for building formwork construction, wherein the water-binder ratio is 0.32-0.36, the volume percentage of coarse aggregate is 29%-31%, and the concrete sand ratio is 51%-53%.

[0029] Another technical solution provided by the present invention is a method for preparing a highly thixotropic self-compacting concrete for building formwork construction, comprising the following steps:

[0030] S1. Fully mix the organic thixotropic modifier and the admixture to obtain a composite admixture;

[0031] S2. When feeding, first add 80% of machine-made sand and cementitious materials, inorganic thixotropic modifier, water and 50% of composite admixture, stir for 1 minute, and prepare mortar with good fluidity;

[0032] S3. Add coarse aggregate, the remaining machine-made sand and composite admixture, stir thoroughly for 2 minutes, and finally obtain highly thixotropic self-compacting concrete suitable for building formwork construction.

[0033] The high thixotropic self-compacting concrete for building formwork construction and the preparation method thereof of the present invention are different from the prior art in that the high thixotropic self-compacting concrete for building formwork construction and the preparation method thereof of the present invention have the following technical effects:

[0034] (1) The present invention uses an organic thixotropic modifier and an inorganic thixotropic modifier simultaneously through two different approaches to improve the thixotropy of concrete. Organic thixotropic modifiers are all high molecular weight polysaccharides, which are composed of monosaccharide units connected by glycosidic bonds, have a linear or branched structure, and can be dissolved in water to form a high viscosity solution or gel with shear thinning properties (i.e., a gel network is formed in a static state to increase the viscosity and yield stress of the concrete; when subjected to shear force, the gel network is destroyed, the viscosity is reduced, and the fluidity is enhanced). Therefore, they are compounded with admixtures for use, thereby giving full play to their potential for improving the thixotropy of concrete. Inorganic thixotropic modifiers are all natural silicate minerals with a layered or fibrous structure. The layered or fibrous particles in these minerals achieve shear thinning through physical crosslinking and adsorption between particles, so they are directly put into the raw materials of concrete as mineral additives for use. By using organic thixotropic modifiers and inorganic thixotropic modifiers simultaneously in different ways, the synergistic effect of the two can be fully exerted. Inorganic particles form a physical cross-linked network in the slurry through their special morphology, while organic polymer polysaccharides further enhance the stability of the network structure through polymer chain entanglement and gelation. The two promote and overlap each other, making the concrete show higher viscosity and yield stress in a static state, and can flow quickly and fill complex structures when subjected to external forces, thus giving the self-compacting concrete excellent high thixotropic properties.

[0035] (2) The present invention obtains a high thixotropic self-compacting concrete for building formwork construction by a reasonable proportion of each component, wherein the reasonable design of the cementitious material system ensures that the concrete slurry has sufficient fluidity, viscosity and wrapping properties; the preferred grading of aggregates ensures that the concrete slurry fully exerts its lubricating effect and provides a skeleton for concrete that is more suitable for filling the complex structure of the formwork; the polycarboxylic acid high-performance admixture can improve the dispersibility of the cementitious material and reduce the water-cement ratio; the use of organic thixotropic modifiers and inorganic thixotropic modifiers provides the mixture with higher thixotropy and improves stability to avoid segregation and bleeding; the high thixotropic self-compacting concrete prepared by the present invention can fully meet the construction requirements of the building formwork concrete entity structure.

[0036] (3) In the technical scheme of the method for preparing highly thixotropic self-compacting concrete, the organic thixotropic modifier and the admixture are first fully mixed to obtain a composite admixture; when adding materials, 80% of machine-made sand and cementitious materials, inorganic thixotropic modifier, water and 50% of the admixture are added in sequence and stirred for 1 minute to improve the homogeneity of the mortar; subsequently, coarse aggregate, the remaining sand and admixture are added and stirred for another 2 minutes to improve the uniformity and workability of the components of the self-compacting concrete, thereby reducing the segregation rate and water bleeding rate of the self-compacting concrete. DETAILED DESCRIPTION

[0037] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0038] The raw materials in the following examples are as follows:

[0039] (1) Cement: 42.5 grade ordinary Portland cement;

[0040] (2) Mineral powder: S95 mineral powder;

[0041] (3) Fly ash: Class C, Grade II fly ash;

[0042] (4) Coarse aggregate: particle size is 5-16 mm, continuous grading, apparent density is 2670 kg / m 3 ;

[0043] (5) Artificial sand: fineness modulus is 2.8, MB is 0.8, and stone powder content is 6.6%;

[0044] (6) Organic thixotropic modifiers: common commercially available gellan gum, xanthan gum and carrageenan;

[0045] (7) Inorganic thixotropic modifiers: common commercially available sepiolite, rectorite and palygorskite;

[0046] (8) Admixture: Use polycarboxylic acid high-performance admixture with a water reduction rate of 25% and a solid content of 15%;

[0047] (9) Mixing water: ordinary tap water.

[0048] Example 1

[0049] The high thixotropic self-compacting concrete used for building formwork construction of the present invention comprises the following components per cubic meter:

[0050] Cementitious material: 530kg,

[0051] Coarse aggregate: 774kg,

[0052] Machine-made sand: 873kg,

[0053] Organic thixotropic modifier: 0.10kg,

[0054] Inorganic thixotropic modifier: 60kg,

[0055] Admixture: 6.4kg,

[0056] Mixing water: 170kg.

[0057] In this embodiment, the cementitious material is composed of 371kg cement, 45kg S95 mineral powder and 114kg Class II fly ash; the sand ratio is 53%; the volume percentage of coarse aggregate is selected to be 29%; and the water-cement ratio is 0.32.

[0058] In this embodiment, the organic thixotropic modifier is prepared by mixing gellan gum and xanthan gum in a ratio of 1:1.

[0059] In this embodiment, the inorganic thixotropic modifier is a mixture of sepiolite and rectorite in a ratio of 1:1.

[0060] In addition, this embodiment also provides a method for preparing highly thixotropic self-compacting concrete for building formwork construction, and the specific steps are as follows:

[0061] S1. Fully mix the organic thixotropic modifier and the admixture to obtain a composite admixture;

[0062] S2. When feeding, first add 80% of machine-made sand and cementitious materials, inorganic thixotropic modifier, water and 50% of composite admixture, stir for 1 minute, and prepare mortar with good fluidity;

[0063] S3. Add coarse aggregate, remaining machine-made sand and composite admixture, stir thoroughly for 2 minutes, and finally obtain highly thixotropic self-compacting concrete suitable for building formwork construction.

[0064] Example 2

[0065] The high thixotropic self-compacting concrete used for building formwork construction of the present invention comprises the following components per cubic meter:

[0066] Cementitious material: 500kg,

[0067] Coarse aggregate: 828kg,

[0068] Machine-made sand: 861kg,

[0069] Organic thixotropic modifier: 0.16kg,

[0070] Inorganic thixotropic modifier: 40kg,

[0071] Admixture: 6.0kg,

[0072] Mixing water: 180kg.

[0073] In this embodiment, the cementitious material is composed of 275kg cement, 90kg S95 mineral powder and 135kg Class II fly ash; the sand ratio is 51%; the volume percentage of coarse aggregate is selected to be 31%; and the water-cement ratio is 0.36.

[0074] In this embodiment, the organic thixotropic modifier is prepared by mixing gellan gum and xanthan gum in a ratio of 1:1.

[0075] In this embodiment, the inorganic thixotropic modifier is a mixture of sepiolite and rectorite in a ratio of 1:1.

[0076] In addition, this embodiment also provides a method for preparing highly thixotropic self-compacting concrete for building formwork construction, and the preparation method is the same as that of Example 1.

[0077] Example 3

[0078] The high thixotropic self-compacting concrete used for building formwork construction of the present invention comprises the following components per cubic meter:

[0079] Cementitious material: 510kg,

[0080] Coarse aggregate: 801kg,

[0081] Machine-made sand: 869kg,

[0082] Organic thixotropic modifier: 0.13kg,

[0083] Inorganic thixotropic modifier: 50kg,

[0084] Admixture: 6.1kg,

[0085] Mixing water: 175kg.

[0086] In this embodiment, the cementitious material is composed of 281kg cement, 77kg S95 mineral powder and 153kg Class II fly ash; the sand ratio is 52%; the volume percentage of coarse aggregate is selected to be 30%; and the water-cement ratio is 0.34.

[0087] In this embodiment, the organic thixotropic modifier is prepared by mixing gellan gum and xanthan gum in a ratio of 1:1.

[0088] In this embodiment, the inorganic thixotropic modifier is a mixture of sepiolite and rectorite in a ratio of 1:1.

[0089] In addition, this embodiment also provides a method for preparing highly thixotropic self-compacting concrete for building formwork construction, and the preparation method is the same as that of Example 1.

[0090] Example 4

[0091] The high thixotropic self-compacting concrete used for building formwork construction of the present invention comprises the following components per cubic meter:

[0092] Cementitious material: 510kg,

[0093] Coarse aggregate: 801kg,

[0094] Machine-made sand: 869kg,

[0095] Organic thixotropic modifier: 0.13kg,

[0096] Inorganic thixotropic modifier: 50kg,

[0097] Admixture: 6.1kg,

[0098] Mixing water: 175kg.

[0099] In this embodiment, the cementitious material is composed of 281kg cement, 77kg S95 mineral powder and 153kg Class II fly ash; the sand ratio is 52%; the volume percentage of coarse aggregate is selected to be 30%; and the water-cement ratio is 0.34.

[0100] In this embodiment, the organic thixotropic modifier is a mixture of gellan gum and carrageenan in a ratio of 1:1.

[0101] In this embodiment, the inorganic thixotropic modifier is a mixture of sepiolite and palygorskite in a ratio of 1:1.

[0102] In addition, this embodiment also provides a method for preparing highly thixotropic self-compacting concrete for building formwork construction, and the preparation method is the same as that of Example 1.

[0103] Example 5

[0104] The high thixotropic self-compacting concrete used for building formwork construction of the present invention comprises the following components per cubic meter:

[0105] Cementitious material: 510kg,

[0106] Coarse aggregate: 801kg,

[0107] Machine-made sand: 869kg,

[0108] Organic thixotropic modifier: 0.13kg,

[0109] Inorganic thixotropic modifier: 50kg,

[0110] Admixture: 6.1kg,

[0111] Mixing water: 175kg.

[0112] In this embodiment, the cementitious material is composed of 281kg cement, 77kg S95 mineral powder and 153kg Class II fly ash; the sand ratio is 52%; the volume percentage of coarse aggregate is selected to be 30%; and the water-cement ratio is 0.34.

[0113] In this embodiment, the organic thixotropic modifier is a mixture of xanthan gum and carrageenan in a ratio of 1:1.

[0114] In this embodiment, the inorganic thixotropic modifier is a mixture of rectorite and palygorskite in a ratio of 1:1.

[0115] In addition, this embodiment also provides a method for preparing highly thixotropic self-compacting concrete for building formwork construction, and the preparation method is the same as that of Example 1.

[0116] Comparative Example 1

[0117] A self-compacting concrete compounded with a thixotropic modifier, comprising the following components per cubic meter:

[0118] Cementitious material: 510kg,

[0119] Coarse aggregate: 801kg,

[0120] Machine-made sand: 869kg,

[0121] Composite thixotropic modifier: 50.13kg,

[0122] Admixture: 6.1kg,

[0123] Mixing water: 175kg.

[0124] In this embodiment, the cementitious material is composed of 281kg cement, 77kg S95 mineral powder and 153kg Class II fly ash; the sand ratio is 52%; the volume percentage of coarse aggregate is selected to be 30%; and the water-cement ratio is 0.34.

[0125] In this embodiment, the composite thixotropic modifier is a mixture of an organic thixotropic modifier and an inorganic thixotropic modifier, and the mass ratio of the organic thixotropic modifier to the inorganic thixotropic modifier is 0.13:50. The organic thixotropic modifier is a mixture of xanthan gum and carrageenan in a ratio of 1:1, and the inorganic thixotropic modifier is a mixture of rectorite and palygorskite in a ratio of 1:1.

[0126] In addition, this embodiment also provides a method for preparing self-compacting concrete using a thixotropic modifier in combination, and the specific steps are as follows:

[0127] S1. When feeding, first add 80% of machine-made sand and cementitious materials, composite thixotropic modifier, water and 50% of admixtures, stir for 1 minute, and prepare mortar with good fluidity;

[0128] S2. Add coarse aggregate, the remaining machine-made sand and admixtures, stir them fully for 2 minutes, and finally obtain self-compacting concrete with thixotropic modifier compound.

[0129] Comparative Example 2

[0130] A high thixotropic self-compacting concrete prepared by a conventional method comprises the following components per cubic meter:

[0131] Cementitious material: 510kg,

[0132] Coarse aggregate: 801kg,

[0133] Machine-made sand: 869kg,

[0134] Organic thixotropic modifier: 0.13kg,

[0135] Inorganic thixotropic modifier: 50kg,

[0136] Admixture: 6.1kg,

[0137] Mixing water: 175kg.

[0138] In this embodiment, the cementitious material is composed of 281kg cement, 77kg S95 mineral powder and 153kg Class II fly ash; the sand ratio is 52%; the volume percentage of coarse aggregate is selected to be 30%; and the water-cement ratio is 0.34.

[0139] In this embodiment, the organic thixotropic modifier is a mixture of xanthan gum and carrageenan in a ratio of 1:1.

[0140] In this embodiment, the inorganic thixotropic modifier is a mixture of rectorite and palygorskite in a ratio of 1:1.

[0141] In addition, this embodiment also provides a method for preparing a high thixotropic self-compacting concrete according to a standard preparation method, and the specific steps are as follows:

[0142] S1. Fully mix the organic thixotropic modifier and the admixture to obtain a composite admixture;

[0143] S2. Mix the coarse aggregate, machine-made sand, cementitious material, inorganic thixotropic modifier, water and composite admixture for 3 minutes to finally obtain a highly thixotropic self-compacting concrete.

[0144] Comparative Example 3

[0145] A highly thixotropic self-compacting concrete prepared by a standard method, comprising the following components per cubic meter:

[0146] Cementitious material: 510kg,

[0147] Coarse aggregate: 801kg,

[0148] Machine-made sand: 869kg,

[0149] Organic thixotropic modifier: 0.13kg,

[0150] Inorganic thixotropic modifier: 50kg,

[0151] Admixture: 6.1kg,

[0152] Mixing water: 175kg.

[0153] In this embodiment, the cementitious material is composed of 281kg cement, 77kg S95 mineral powder and 153kg Class II fly ash; the sand ratio is 52%; the volume percentage of coarse aggregate is selected to be 30%; and the water-cement ratio is 0.34.

[0154] In addition, this embodiment also provides a method for preparing a high thixotropic self-compacting concrete according to a standard preparation method, and the specific steps are as follows:

[0155] S1. Mix coarse aggregate, machine-made sand, cementitious material, water and admixture for 3 minutes to finally obtain self-compacting concrete.

[0156] Comparative Example 4

[0157] A self-compacting concrete without using an organic thixotropic modifier comprises the following components per cubic meter:

[0158] Cementitious material: 510kg,

[0159] Coarse aggregate: 801kg,

[0160] Machine-made sand: 869kg,

[0161] Inorganic thixotropic modifier: 50kg,

[0162] Admixture: 6.1kg,

[0163] Mixing water: 175kg.

[0164] In this embodiment, the cementitious material is composed of 281kg cement, 77kg S95 mineral powder and 153kg Class II fly ash; the sand ratio is 52%; the volume percentage of coarse aggregate is selected to be 30%; and the water-cement ratio is 0.34.

[0165] In this embodiment, the inorganic thixotropic modifier is a mixture of rectorite and palygorskite in a ratio of 1:1.

[0166] In addition, this comparative example also provides a method for preparing a self-compacting concrete without using an organic thixotropic modifier, and the specific steps are as follows:

[0167] S1. When feeding, first add 80% of machine-made sand and cementitious materials, inorganic thixotropic modifier, water and 50% of admixtures, stir for 1 minute, and prepare mortar with good fluidity;

[0168] S2. Add coarse aggregate, the remaining machine-made sand and composite admixture, stir thoroughly for 2 minutes, and finally obtain self-compacting concrete without using organic thixotropic modifier.

[0169] Comparative Example 5

[0170] A self-compacting concrete without using an inorganic thixotropic modifier, comprising the following components per cubic meter:

[0171] Cementitious material: 510kg,

[0172] Coarse aggregate: 801kg,

[0173] Machine-made sand: 869kg,

[0174] Organic thixotropic modifier: 0.13kg,

[0175] Admixture: 6.1kg,

[0176] Mixing water: 175kg.

[0177] In this embodiment, the cementitious material is composed of 281kg cement, 77kg S95 mineral powder and 153kg Class II fly ash; the sand ratio is 52%; the volume percentage of coarse aggregate is selected to be 30%; and the water-cement ratio is 0.34.

[0178] In this embodiment, the organic thixotropic modifier is a mixture of xanthan gum and carrageenan in a ratio of 1:1.

[0179] In addition, this comparative example also provides a method for preparing a self-compacting concrete without using an inorganic thixotropic modifier, and the specific steps are as follows:

[0180] S1. Fully mix the organic thixotropic modifier and the admixture to obtain a composite admixture;

[0181] S2. When adding materials, first add 80% of machine-made sand and cementitious materials, water and 50% of composite admixtures, stir for 1 minute, and prepare mortar with good fluidity;

[0182] S3. Add coarse aggregate, the remaining machine-made sand and composite admixture, stir thoroughly for 2 minutes, and finally obtain self-compacting concrete without using inorganic thixotropic modifier.

[0183] The concrete of Examples 1-5 and Comparative Examples 1-5 were subjected to performance tests, and the test results are shown in Table 1.

[0184] Table 1 Concrete performance test results

[0185]

[0186] In combination with Examples 1-3, it can be seen that by reasonably mixing the components in the present invention, a highly thixotropic self-compacting concrete for building formwork construction can be obtained, and different consistencies can be obtained by adjusting the ratio of the components in the present invention according to different project requirements.

[0187] In combination with Examples 3-5, it can be seen that by using different types of organic thixotropic modifiers and inorganic thixotropic modifiers involved in the present invention, the performance indicators of the highly thixotropic self-compacting concrete obtained are not much different, and the formula of the organic thixotropic modifier and the inorganic thixotropic modifier can be flexibly adjusted according to the difficulty of obtaining materials and changes in material prices.

[0188] Combining Example 5 with Comparative Example 1, it can be seen that the preferred method of using the organic thixotropic modifier and the inorganic thixotropic modifier of the present invention can exert the potential of both to improve the thixotropy of concrete to a greater extent than directly compounding the two.

[0189] Combining Example 5 with Comparative Example 2, it can be seen that the preferred high thixotropic self-compacting concrete mixing process design technical solution of the present invention can more fully stimulate the self-compacting property and high thixotropy of the concrete in the present invention.

[0190] Combining Example 5 with Comparative Example 3, it can be seen that the high thixotropic self-compacting concrete prepared by the present invention for building formwork construction has an increased viscosity and reduced fluidity compared with conventional self-compacting concrete; the J-ring expansion difference, V-funnel passage time, and U-box ΔH data are reduced, indicating that the comprehensive performance of the high thixotropic self-compacting concrete for building formwork construction in terms of filling, gap passability, thixotropy, and anti-segregation is improved; the slurry seepage rate and 28d electric flux are significantly reduced, while the 28d coring strength is significantly increased, indicating that the high thixotropic self-compacting concrete for building formwork construction of the present invention can effectively prevent the slurry from seeping out of the formwork holes, ensure the compactness of the building formwork entity structure, thereby improving the entity strength and improving the durability of the entity structure.

[0191] Combining Example 5 with Comparative Examples 4-5, it can be seen that when an organic thixotropic modifier or an inorganic thixotropic modifier is used alone, the performance of the self-compacting concrete can be optimized to a certain extent. However, when the organic thixotropic modifier and the inorganic thixotropic modifier are used in combination, a significant synergistic effect is produced between the two, making the optimization effect on the performance of the self-compacting concrete more significant and comprehensive.

[0192] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A highly thixotropic self-compacting concrete for building formwork construction, characterized in that: Each cubic meter includes components: Cementitious material: 500-530kg, Coarse aggregate: 774~828kg, Machine-made sand: 861-873kg, Organic thixotropic modifier: 0.10~0.16kg, Inorganic thixotropic modifier: 40-60kg, Admixture: 6.0~6.4kg, Mixing water: 170~180kg.

2. The highly thixotropic self-compacting concrete for building formwork construction according to claim 1, characterized in that: The organic thixotropic modifier is a high molecular weight polysaccharide, which is used in combination with an additive. The organic thixotropic modifier is a mixture of one or more of gellan gum, xanthan gum or carrageenan.

3. The highly thixotropic self-compacting concrete for building formwork construction according to claim 1, characterized in that: The inorganic thixotropic modifier is a natural silicate mineral used as a mineral additive. The inorganic thixotropic modifier is a mixture of one or more of sepiolite, rectorite or palygorskite.

4. The highly thixotropic self-compacting concrete for building formwork construction according to claim 1, characterized in that: The cementitious material is composed of 42.5 grade ordinary Portland cement, S95 mineral powder and Class C II fly ash, wherein: The mass percentage of cement in cementitious materials is 55-70%. The total mass percentage of mineral powder and fly ash in cementitious materials is 30-45%. The ratio of mineral powder to fly ash is 2:5 to 2:

3.

5. The highly thixotropic self-compacting concrete for building formwork construction according to claim 1, characterized in that: The particle size of the coarse aggregate is 5 to 16 mm, with continuous grading.

6. The highly thixotropic self-compacting concrete for building formwork construction according to claim 1, characterized in that: The particle size of the machine-made sand is 0.16 mm to 5 mm, the fineness modulus is 2.6 to 3.2, the MB value is less than 1.0, and the stone powder content is 5 to 8%.

7. The highly thixotropic self-compacting concrete for building formwork construction according to claim 1, characterized in that: The admixture is a polycarboxylic acid high-performance admixture with a water reduction rate of not less than 25% and a solid content of 15%.

8. The highly thixotropic self-compacting concrete for building formwork construction according to claim 1, characterized in that: The water-cement ratio is selected to be 0.32-0.36, the volume percentage of coarse aggregate is selected to be 29%-31%, and the concrete sand ratio is selected to be 51%-53%.

9. A method for preparing a highly thixotropic self-compacting concrete for building formwork construction, characterized in that: The following steps are involved: S1. Fully mix the organic thixotropic modifier and the admixture to obtain a composite admixture; S2. When feeding, first add 80% of machine-made sand and cementitious materials, inorganic thixotropic modifier, water and 50% of composite admixture, stir for 1 minute, and prepare mortar with good fluidity; S3. Add coarse aggregate, the remaining machine-made sand and composite admixtures, stir thoroughly for 2 minutes to obtain the finished product.

Images