Concrete based on calcined kaolin-limestone powder low-carbon LC3 cementing material

Abstract

The invention discloses concrete based on a calcined kaolin-limestone powder low-carbon LC3 cementing material, which adopts a quaternary composite cementing material system of cement clinker, calcined kaolin, limestone powder and gypsum. A multi-component synergistic LC3 exclusive system is constructed by utilizing a pozzolanic effect of calcined kaolin, a crystal nucleus effect of limestone powder and hydration regulation and control of gypsum, so that high-added-value utilization is realized by utilizing industrial wastes, the cement consumption and CO2 emission are reduced, the cost is optimized, and meanwhile, the strength, durability and toughness are also improved; the novel low-carbon, high-performance and low-cost ECC concrete system is constructed, the problem of large-scale application of ECC is solved, the requirements of the building industry can be met, and the novel low-carbon, high-performance and low-cost ECC concrete system has remarkable environmental, economic and social benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a low-carbon LC based on calcined kaolin-limestone powder. 3 Cementitious concrete. Background Art

[0002] As global awareness of climate change and environmental protection increases, the construction industry, as one of the main sources of carbon emissions, is facing tremendous pressure to transform to a low-carbon and environmentally friendly industry. Traditional cement raw materials used in concrete generate large amounts of carbon dioxide emissions during the production process, which not only exacerbates the greenhouse effect but also has a serious impact on the ecological environment. Therefore, the development of low-carbon cementitious materials to replace or partially replace traditional cement has become a research hotspot in the current field of building materials. In recent years, the use of industrial solid waste, urban garbage and other waste to prepare low-carbon cementitious materials has become an important direction. Among them, calcined kaolin and limestone powder, as common industrial waste, have abundant sources and potential application value.

[0003] Engineered cementitious composites (ECCs), as an ultra-high-performance concrete with excellent performance, can overcome the brittle defects of traditional concrete and achieve ultra-high tensile ductility, tensile strain hardening, and crack propagation inhibition in concrete. ECC concrete is typically formulated with low fine aggregate and no coarse aggregate to optimize and enhance material performance. However, this design significantly increases the amount of cement in ECC, to approximately two to three times that of traditional concrete. While the synergistic effect of high cement content and polymer fibers gives ECC excellent performance, it also inevitably brings about problems such as high energy consumption, large carbon emissions, and increased production costs, which restrict the large-scale promotion and application of this material.

[0004] After searching, the existing Chinese invention application document with publication number CN116988381A discloses an assembled full FRP bridge deck structure and its construction method, wherein the ECC high-toughness fiber cement-based composite material used for cast-in-place ECC wet joints includes cement, fly ash, limestone powder, metakaolin, silica fume, water reducer, PVA fiber with a length of 12mm, 1m 3The masses of cement, fly ash, limestone powder, metakaolin, silica fume, water, sand, water reducer, and PVA fiber in the ECC high-toughness fiber-cement composite are 552kg, 690kg, 55.2kg, 55.2kg, 27.6kg, 358.8kg, 496.8kg, 138kg, and 24kg, respectively. The high cement content in this composite leads to high CO2 emissions, making it difficult to achieve low-carbon emission reduction goals. Furthermore, the lack of synergy between its components makes it unable to meet ECC's requirements for fiber dispersion and high performance. For example, the metakaolin and silica fume in this composite are both highly active pozzolanic materials. They have overlapping functions in the system and require a large amount of water, which can easily lead to uneven fiber dispersion due to the high amount of water reducer required.

[0005] For example, the Chinese invention application document with the existing publication number CN119100709A discloses a low-carbon, high-strength water-resistant cement-based composite material, its preparation method and application. Although the composite material adopts a calcined clay-limestone powder-gypsum system to reduce the amount of cement, the cement still accounts for a high proportion and the low-carbon property is insufficient; moreover, the ternary system of calcined clay-limestone-gypsum in the composite material lacks clinker synergy and cannot be directly adapted to LC. 3 chemical reaction path; at the same time, the high-strength polyethylene fiber used in the composite material has low density and large aspect ratio, which makes the fiber-matrix interaction mechanism in the composite material more dependent on high-speed stirring in the process, which has certain limitations. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention aims to provide a low carbon LC based on calcined kaolin-limestone powder. 3 The concrete of cementitious materials adopts a four-component composite cementitious material system of cement clinker, calcined kaolin, limestone powder and gypsum, and utilizes the volcanic ash effect of calcined kaolin, the crystal nucleation effect of limestone powder and the hydration regulation of gypsum to construct a multi-component synergistic LC 3 The exclusive system constructs a new low-carbon, high-performance, low-cost ECC concrete system; at the same time, compared with the fiber-matrix interaction mechanism that relies on high-speed stirring, the present invention only needs to regulate the cohesiveness of the slurry through the thickener to ensure uniform dispersion, and its interfacial interaction with the matrix focuses more on improving toughness.

[0007] To achieve the above-mentioned and other related purposes, the present invention adopts the following technical solutions:

[0008] The present invention provides a low-carbon LC based on calcined kaolin-limestone powder 3 The cementitious concrete comprises the following components in parts by weight:

[0009] LC 3405-565 parts of cementitious material, 691-751 parts of fly ash, 452-462 parts of quartz sand, 314-405 parts of water, 6.28-11.56 parts of water reducer, 23-25 ​​parts of PVA fiber, and 0.578-0.628 parts of thickener;

[0010] wherein the LC 3 The cementitious material consists of cement clinker, calcined kaolin, limestone powder and gypsum.

[0011] As a preferred technical solution, in the LC 3 The components and their mass percentages in the cementitious material are: 50% to 60% of cement clinker, 25% to 30% of calcined kaolin, 10% to 15% of limestone powder, and 3% to 5% of gypsum.

[0012] Furthermore, the cement clinker is general-purpose Portland cement clinker, with a burning rate of 0.36% to 0.42%, a 3d compressive strength of 36.1 MPa, and a 7d compressive strength of 63.9 MPa.

[0013] Furthermore, the calcined kaolin has a fineness of 1250 mesh, an Al2O3 content of 36% to 43%, and a SiO2 content of 45% to 52%.

[0014] Furthermore, the limestone powder has a fineness of 325 mesh, an MB value of 0.50 g / kg, a fluidity ratio of 102%, a 7d compressive strength ratio of 66%, and a 28d compressive strength ratio of 68%.

[0015] Furthermore, the gypsum is dihydrate gypsum, the main component of which is CaSO4·2H2O, and the calcium sulfate content is ≥98%.

[0016] As a preferred technical solution, the surface of the PVA fiber is treated with an oil film process, and the length is 12 mm, the diameter is 39 mm, and the density is 1.3 g / cm 3 , tensile strength is 1600MPa and elastic modulus is 40GPa.

[0017] As a preferred technical solution, the water reducer is a polycarboxylic acid type high-efficiency water reducer, and the thickener is hydroxypropyl methylcellulose.

[0018] As a preferred technical solution, the particle size range of the quartz sand is 140-200 mesh.

[0019] As described above, the present invention has the following beneficial effects:

[0020] (1) A low-carbon LC based on calcined kaolin-limestone powder of the present invention 3Cementitious concrete is based on the technology of industrial solid waste resource utilization, and uses industrial waste such as calcined kaolin and limestone powder as raw materials to prepare LC 3 Low-carbon cementitious materials utilize the volcanic ash effect of calcined kaolin to consume cement hydration products through secondary reaction, utilize the nucleation effect of limestone powder to optimize the slurry composition and promote hydration, utilize the hydration regulation of gypsum to stabilize the system, and combine the three with cement clinker to construct a unique four-component composite LC of cement clinker, calcined kaolin, limestone powder and gypsum. 3 The cementitious material system can achieve high-value-added utilization of industrial waste while effectively reducing high carbon emissions in traditional cement production, providing core technical support for the construction industry to achieve the "dual carbon" goals; at the same time, the abundance and low-cost characteristics of industrial waste significantly reduce raw material costs, optimize mix ratios and reduce resource consumption, effectively control production costs, and overcome the key difficulties that restrict the large-scale application of ECC, paving the way for its widespread application in the construction field, and bringing significant economic and social benefits.

[0021] (2) A low-carbon LC based on calcined kaolin-limestone powder of the present invention 3 Concrete made of cementitious materials uses industrial waste such as calcined kaolin and limestone powder to reduce cement consumption from the source, significantly reducing CO2 emissions during cement production and achieving low-carbon emission reduction goals; in addition, the calcined kaolin and limestone powder compound has a synergistic coupling effect, which can strengthen the dense accumulation of carbon aluminate hydrates, refine the pore structure, and significantly improve the strength of cementitious materials. The synergistic effect of the high activity of calcined kaolin and the nucleation effect of limestone powder can promote hydration reaction, improve concrete strength and durability, and ensure the high In terms of performance, compared with ordinary Portland cement (OPC), this system can generate additional low-density hydration products (such as hydrated calcium silicate aluminate, etc.) during the hydration process. At the same time, the continuous pozzolanic reaction of calcined kaolin can further promote the formation of hydrated calcium silicate aluminate and reduce the gel pores in the microstructure, making the system have a higher pore filling effect than OPC; in addition, the use of thickeners regulates the cohesiveness of the slurry, ensures that the PVA fibers are evenly dispersed in the concrete, further improves the toughness of the concrete, and meets the performance requirements of the construction industry for materials.

[0022] (3) A low-carbon LC based on calcined kaolin-limestone powder of the present invention 3Concrete with cementitious materials addresses the high energy consumption and increased costs caused by high cement content in ECC. It utilizes abundant and low-cost industrial waste such as calcined kaolin and limestone powder as cementitious materials to reduce cement content, which not only reduces CO2 emissions but also significantly reduces raw material costs. At the same time, it optimizes the material mix ratio to reduce unnecessary resource consumption and effectively controls production costs, solving the key problems that restrict the large-scale promotion and application of ECC, paving the way for its widespread application in the construction field, and has significant economic and social benefits. By synergizing calcined kaolin with cement clinker, strength development can be optimized, so that the concrete has both early strength and later durability. Moreover, by combining the thickener with PVA fiber, the fiber dispersion can be ensured by regulating the viscosity of the slurry, thereby improving toughness, and meeting the performance requirements of different application scenarios, such as prefabricated structures and areas with high crack resistance requirements, thus expanding the application range of ECC concrete. BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION

[0023] In order to better understand the technical solution of the present invention, the following examples are listed. It should be noted that in the description of the present invention, the raw materials, reactions and post-processing methods appearing in this specification, unless otherwise stated or specified, are all well-known commercially available chemical raw materials and technical means well known to those skilled in the art.

[0024] Example 1

[0025] This embodiment provides a low-carbon LC based on calcined kaolin-limestone powder 3 Cementitious concrete is made from the following raw material components and quantities:

[0026] LC 3 Cementitious material 565kg / m 3 、Fly ash 691kg / m 3 , quartz sand 452kg / m 3 , water 314kg / m 3 , water reducing agent 6.28kg / m 3 , PVA fiber 25kg / m 3 , thickener 0.628kg / m 3 .

[0027] wherein the LC 3 The cementitious material is cement clinker 283kg / m 3 , calcined kaolin 170kg / m 3 , limestone powder 85kg / m 3 , gypsum 28kg / m 3 composition.

[0028] The concrete in this embodiment is prepared by the following preparation method, which includes the following steps:

[0029] S1. Powder premix: weigh LC according to the amount of each component. 3 Cementitious materials, fly ash and quartz sand are poured into a mixer and dry mixed for 2 minutes until a uniform dry mixture is obtained;

[0030] S2. Preparation of liquid components: Add the water reducer and thickener to a predetermined amount of water, stir and dissolve until uniform, to form a mixed liquid;

[0031] S3, wet mixing stage: the mixed liquid obtained in step S2 is added to the dry mixed material in step S1 at one time, and wet mixed for 6 minutes until the materials are evenly mixed to obtain a wet mix;

[0032] S4, fiber dispersion: PVA fibers are dispersed and evenly added to the wet mix obtained in step S3, and stirred for 5 minutes to ensure that the PVA fibers are thoroughly dispersed to obtain an ECC mixture;

[0033] S5, molding and initial curing: Pour the ECC mixture prepared in step S4 into a pre-prepared mold, place it on a vibration table and vibrate it for 1 minute until it is dense, cover it with plastic wrap, place it in a standard curing room, and demold it after leaving it for 24 hours;

[0034] S6. Demolding and curing: After demoulding, mark and place in a standard curing room for curing to the specified age.

[0035] Furthermore, the temperature of the standard curing room in step S5 is 20±2° C., and the relative humidity is ≥95%; and the curing period in step S6 is 28 days.

[0036] in:

[0037] The cement clinker is general-purpose Portland cement clinker, with a burning rate of 0.36% to 0.42%, a 3d compressive strength of 36.1 MPa, and a 7d compressive strength of 63.9 MPa.

[0038] The calcined kaolin has a fineness of 1250 meshes, an Al2O3 content of 36% to 43%, and a SiO2 content of 45% to 52%.

[0039] The limestone powder has a fineness of 325 mesh, an MB value of 0.50 g / kg, a fluidity ratio of 102%, a 7d compressive strength ratio of 66%, and a 28d compressive strength ratio of 68%.

[0040] The gypsum is dihydrate gypsum, the main component of which is CaSO4·2H2O, and the calcium sulfate content is ≥98%.

[0041] The quartz sand is selected high-quality quartz sand with a mesh size of 140-200.

[0042] The water is laboratory tap water.

[0043] The water reducer is a polycarboxylic acid type high efficiency water reducer with a water reduction rate of 28% and a solid content of 22%.

[0044] The PVA fiber surface is treated with oil film technology, with a length of 12 mm, a diameter of 39 mm, and a density of 1.3 g / cm 3 , tensile strength is 1600MPa and elastic modulus is 40GPa.

[0045] The thickener is hydroxypropyl methylcellulose.

[0046] Example 2

[0047] This embodiment provides a low-carbon LC based on calcined kaolin-limestone powder 3 Cementitious concrete is made from the following raw material components and quantities:

[0048] LC 3 Cementitious material 565kg / m 3 , fly ash 691kg / m 3 , quartz sand 452kg / m 3 , water 314kg / m 3 , water reducing agent 6.28kg / m 3 , PVA fiber 25kg / m 3 , Hydroxypropyl methylcellulose 0.628kg / m 3 .

[0049] wherein the LC 3 The cementitious material is composed of cement clinker 339kg / m 3 , calcined kaolin 141kg / m 3 , limestone powder 57kg / m 3 , gypsum 28kg / m 3 composition.

[0050] The difference between Example 2 and Example 1 is that the LC in Example 1 is replaced by 3 The amounts of the components of the cementitious material were adjusted, the amount of cement clinker was increased, and the amounts of calcined kaolin and limestone powder were reduced; the preparation method was the same as in Example 1.

[0051] Comparative Example 1

[0052] This embodiment provides an ordinary cement-based concrete, which is made from the following raw material components and amounts:

[0053] P·O42.5 cement 565kg / m3 , fly ash 691kg / m 3 , quartz sand 452kg / m 3 , water 314kg / m 3 , water reducing agent 6.28kg / m 3 , PVA fiber 25kg / m 3 , Hydroxypropyl methylcellulose 0.628kg / m 3 The difference from Example 1 is that P·O42.5 cement is used to replace LC 3 Cementitious material.

[0054] The difference between Comparative Example 1 and Example 1 is that the LC in Example 1 3 The total amount of cementitious materials used was replaced by P·O42.5 cement; and the preparation method was the same as in Example 1.

[0055] Example 3

[0056] This embodiment provides a low-carbon LC based on calcined kaolin-limestone powder 3 Cementitious concrete is made from the following raw material components and quantities:

[0057] LC 3 Cementitious material 405kg / m 3 , fly ash 751kg / m 3 , quartz sand 462kg / m 3 , water 405kg / m 3 , water reducing agent 11.56kg / m 3 , PVA fiber 23kg / m 3 , Hydroxypropyl methylcellulose 0.578kg / m 3 .

[0058] wherein the LC 3 The cementitious material is cement clinker 202kg / m 3 , calcined kaolin 121kg / m 3 , limestone powder 61kg / m 3 , gypsum 20kg / m 3 composition.

[0059] The difference between Example 3 and Example 1 is that: while maintaining Example 1, the LC 3 While the proportions of the various components of the gelling material remain essentially unchanged, the LC in Example 1 is reduced. 3 The total amount of cementitious material used is increased, and the proportions of fly ash, quartz sand, water, and water reducer are increased, while the proportions of PVA fiber and hydroxypropyl methylcellulose are reduced; the preparation method is the same as Example 1.

[0060] Example 4

[0061] This embodiment provides a low-carbon LC based on calcined kaolin-limestone powder 3 Cementitious concrete is made from the following raw material components and quantities:

[0062] The difference between Example 4 and Example 3 is that the LC in Example 3 is replaced by 3 The amounts of the components of the cementitious material were adjusted, the amount of cement clinker was increased, and the amounts of calcined kaolin and limestone powder were reduced; the preparation method was the same as that of Example 3.

[0063] Comparative Example 2

[0064] This embodiment provides an ordinary cement-based concrete, which is made from the following raw material components and amounts:

[0065] The difference between Comparative Example 1 and Example 3 is that the LC in Example 1 3 The total amount of cementitious materials used was replaced by P·O42.5 cement; the preparation method was the same as that in Example 3.

[0066] In summary, the raw material components and amounts of each embodiment and comparative example are shown in Table 1:

[0067] Table 1 Raw materials for Examples and Comparative Examples (kg / m 3 )

[0068]

[0069] According to JC / T2461-2018 "Test Method for Mechanical Properties of High Ductility Fiber Reinforced Cement-Based Composite Materials", the cube compressive strength and flexural strength tests were performed on Examples 1 to 4 and Comparative Examples 1 to 2. The results are shown in Table 2:

[0070] Table 2 Performance test data table

[0071] project Cube compressive strength (MPa) Flexural strength (MPa) Example 1 57.1 13.6 Example 2 57.6 13.7 Comparative Example 1 55.4 12.3 Example 3 37.8 9.2 Example 4 39.2 8.9 Comparative Example 2 37.2 8.4

[0072] Combining Examples 1 to 4 and Comparative Examples 1 to 2 and Tables 1 and 2, it can be seen that the addition of calcined kaolin-limestone powder low carbon LC 3 Cementitious materials have a good performance in improving the compressive and flexural strength of ECC concrete, and the strengthening effect is more significant when the amount of cement clinker is increased. Through the synergistic effect of the active reaction of calcined kaolin and the fiber, LC 3 The ECC concrete shows a significant toughness advantage, as analyzed below:

[0073] Combined with the raw material table in Table 1, it can be seen that Examples 1 to 4 all use LC composed of cement clinker, calcined kaolin, limestone powder, and gypsum. 3Cementitious material system, while Comparative Examples 1 and 2 only use conventional P·O42.5 cement as the cementitious material. From the performance test data in Table 2, it can be seen that, with the same total amount of cementitious material, compared with Comparative Example 1, the compressive strength of the cube of Example 1 increased by 3.1%, and the flexural strength increased by 10.6%; the compressive strength of the cube of Example 2 increased by 4.0%, and the flexural strength increased by 11.4%. Compared with Comparative Example 2, the compressive strength of the cube of Example 3 increased by 1.6%, and the flexural strength increased by 9.5%; the compressive strength of the cube of Example 4 increased by 5.4%, and the flexural strength increased by 6.0%. This LC 3 The cementitious material system reacts with cement hydration products through the volcanic ash effect of calcined kaolin to generate more cementitious products, thereby improving the strength and density of concrete. In addition, the nucleation effect of limestone powder optimizes the particle size distribution of cement paste, promotes the hydration reaction, and further improves the performance of concrete. At the same time, gypsum plays a role in regulating hydration in the system, stabilizing the volume of concrete and reducing the risk of cracking. In addition, this LC 3 The cementitious material system utilizes calcined kaolin and limestone powder as high-value-added industrial waste, which not only reduces the amount of cement clinker and carbon dioxide emissions, but also reduces the cost of raw materials, and has significant economic and environmental value.

[0074] At the same time, combined with the raw material table in Table 1 and the performance test data in Table 2, it can be seen that the amount of cement clinker used in Example 1 and Example 2 is increased compared with that in Example 3 and Example 4, forming a more efficient low-carbon cementitious material system than that in Example 3 and Example 4. By reasonably adjusting LC 3 Increasing the composition ratio of cementitious materials and the amount of cement clinker can further exert the synergistic effect of calcined kaolin and limestone powder and improve the mechanical properties of ECC concrete. At the same time, the use of thickener improves the cohesion of the slurry, ensures the uniform dispersion of PVA fibers in concrete, and makes the interface effect between the fiber and the matrix focus more on improving toughness, thereby enhancing the crack resistance of concrete.

[0075] Further, by analyzing the data in Table 1 and Table 2, it can be found that in LC 3When the total amount of cementitious materials and other raw material components are exactly the same, when the amount of cement clinker is increased, such as Example 2 compared with Example 1, and Example 4 compared with Example 3, the cube compressive strength and flexural strength are both improved. This shows that cement clinker still plays a key role in contributing strength in the cementitious material system, and the synergistic effect with calcined kaolin, limestone powder and gypsum can further enhance the performance of concrete; in addition, the addition of PVA fiber and its good interaction with the matrix also play an important role in improving the toughness of concrete; and the active reaction of calcined kaolin and the synergistic effect of fiber work together to make LC 3 ECC concrete exhibits a more significant toughness advantage, which can effectively resist the generation and expansion of cracks and improve the service life and durability of concrete.

[0076] In summary, in combination with Examples 1 to 4 and Comparative Examples 1 to 2 and in combination with Tables 1 and 2, it can be clearly seen that the synergistic effect of the components and process conditions of the present invention is that the low-carbon LC based on calcined kaolin-limestone powder of the present invention 3 The concrete of cementitious materials adopts a four-component composite cementitious material system consisting of cement clinker, calcined kaolin, limestone powder and gypsum, and utilizes the volcanic ash effect of calcined kaolin, the crystal nucleation effect of limestone powder and the hydration regulation of gypsum to construct a multi-component synergistic LC 3 This proprietary system not only improves the compressive and flexural strength of ECC concrete, but also achieves low-carbon emission reduction goals. Furthermore, a thickener regulates the paste's cohesiveness to ensure uniform dispersion of PVA fibers, enhancing the concrete's toughness. Compared to Comparative Examples 1 and 2, the concrete of this invention effectively reduces cement usage and carbon emissions while maintaining strength and durability. This offers significant economic and environmental benefits, making it more suitable for modern green building projects.

[0077] Therefore, the low carbon LC based on calcined kaolin-limestone powder in the present invention 3 Concrete prepared from cementitious materials can make full use of industrial waste, realize the recycling of resources and the balanced development of the ecological environment, and conform to the concept of sustainable development. At the same time, applying it to ECC concrete can not only significantly reduce carbon dioxide emissions, but also help optimize comprehensive technical indicators, expand its application scope in complex engineering scenarios, and provide strong support for the low-carbon transformation of the construction industry.

[0078] The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Furthermore, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A low carbon LC based on calcined kaolin-limestone powder 3 Concrete of cementitious material, characterized in that Contains the following components in parts by weight: LC 3 405-565 parts of cementitious material, 691-751 parts of fly ash, 452-462 parts of quartz sand, 314-405 parts of water, 6.28-11.56 parts of water reducer, 23-25 ​​parts of PVA fiber, and 0.578-0.628 parts of thickener; wherein the LC 3 The cementitious material consists of cement clinker, calcined kaolin, limestone powder and gypsum.

2. A low-carbon LC based on calcined kaolin-limestone powder according to claim 1 3 Concrete of cementitious material, characterized in that In the LC 3 The components and their mass percentages in the cementitious material are: 50% to 60% of cement clinker, 25% to 30% of calcined kaolin, 10% to 15% of limestone powder, and 3% to 5% of gypsum.

3. A low-carbon LC based on calcined kaolin-limestone powder according to claim 1 or 2 3 Concrete of cementitious material, characterized in that The cement clinker is general-purpose Portland cement clinker, with a burning rate of 0.36% to 0.42%, a 3d compressive strength of 36.1 MPa, and a 7d compressive strength of 63.9 MPa.

4. A low-carbon LC based on calcined kaolin-limestone powder according to claim 1 or 2 3 Concrete of cementitious material, characterized in that The calcined kaolin has a fineness of 1250 meshes, an Al2O3 content of 36% to 43%, and a SiO2 content of 45% to 52%.

5. A low-carbon LC based on calcined kaolin-limestone powder according to claim 1 or 2 3 Concrete of cementitious material, characterized in that The limestone powder has a fineness of 325 mesh, an MB value of 0.50 g / kg, a fluidity ratio of 102%, a 7d compressive strength ratio of 66%, and a 28d compressive strength ratio of 68%.

6. A low-carbon LC based on calcined kaolin-limestone powder according to claim 1 or 2 3 Concrete of cementitious material, characterized in that The gypsum is dihydrate gypsum, the main component of which is CaSO4·2H2O, and the calcium sulfate content is ≥98%.

7. A low-carbon LC based on calcined kaolin-limestone powder according to claim 1 3 Concrete of cementitious material, characterized in that The PVA fiber surface is treated with oil film technology, with a length of 12 mm, a diameter of 39 mm, and a density of 1.3 g / cm 3 , tensile strength is 1600MPa and elastic modulus is 40GPa.

8. A low-carbon LC based on calcined kaolin-limestone powder according to claim 1 3 Concrete of cementitious material, characterized in that The water reducer is a polycarboxylic acid type high efficiency water reducer, and the thickener is hydroxypropyl methylcellulose.

9. A low-carbon LC based on calcined kaolin-limestone powder according to claim 1 3 Concrete of cementitious material, characterized in that The particle size range of the quartz sand is 140-200 mesh.

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