Blast furnace slag-based geopolymer concrete composition design method

Abstract

The invention discloses a blast furnace slag-based geopolymer concrete composition design method, and belongs to the technical field of building materials. The method comprises the following steps: (1) based on an aggregate ternary composition diagram, optimizing aggregate gradation by adopting a triangular single centroid method; (2) determining a water-solid ratio and an alkali-solid ratio according to the target strength; (3) determining the slurry demand according to the target slump; (4) on the basis of the sodium silicate-sodium carbonate-active MgO ternary diagram, optimizing the composition of the excitant through a coordinate transformation contour map; (5) optimizing aluminosilicate composition based on a slag-fly ash-fired clay-based volcanic ash material ternary diagram; and (6) completing concrete proportion calculation. According to the method, through multi-component collaborative optimization design, the problems of quick setting and high shrinkage of geopolymer concrete are solved, and the working performance and durability are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a composition design method for blast furnace slag-based polymer concrete. Background Art

[0002] Geopolymer concrete is a cementitious concrete material prepared from chemically activated aluminosilicate waste. Compared to traditional Portland cement, geopolymer concrete offers low energy consumption, high strength, and excellent durability, and has broad application prospects in building materials, high-strength, and corrosion-resistant materials. Blast furnace slag-based geopolymer concrete, the most widely studied cementitious material, remains limited in its engineering applications by inadequate theoretical research into its compositional design. Existing methods struggle to systematically optimize key parameters such as aggregate packing density, activator ratio, and aluminosilicate composition, resulting in concrete properties (such as setting time, shrinkage, and strength) that cannot be precisely matched to engineering requirements.

[0003] Chinese patent CN106007541A discloses a high-performance concrete design method based on multiple performance requirements, which provides a basis for the design of cementitious material components. However, there are significant differences in the composition design of blast furnace slag-based polymer concrete: The factors affecting strength are complex: the water-solid ratio, alkali-solid ratio, slag replacement ratio, etc. are different from those of traditional silicate concrete; Ternary gelling system: the ratio of solid activator (sodium silicate-sodium carbonate) and mineral admixture (active MgO) needs to be optimized simultaneously; Special constraints: Content constraints (e.g., 60-100% sodium silicate) need to be incorporated into the ternary composition design through coordinate transformation; Workability correlation: The slurry requirement needs to be determined based on the target workability (such as slump) and the excess slurry thickness.

[0004] Existing methods do not specifically address the above problems, which restricts the precise control of material properties and engineering applications. Summary of the Invention

[0005] The present invention provides a blast furnace slag-based polymer concrete composition design method, which can effectively solve at least one technical problem involved in the background technology.

[0006] To achieve the above object, the technical solution of the present invention is: A method for designing a composition of blast furnace slag-based polymer concrete comprises the following steps: Step S1, based on the aggregate ternary composition diagram, a bulk density experiment is set up using the triangle single centroid method, and the optimal aggregate composition is determined according to the bulk density contour map; Step S2, determining the water-to-solid ratio and the alkali-to-solid ratio based on the target strength; wherein the water in the water-to-solid ratio is the sum of the mass of the blending water and the water in the activator, the alkali in the alkali-to-solid ratio is the mass of the sodium oxide in the activator, and the solid phase in the water-to-solid ratio and the alkali-to-solid ratio is the sum of the mass of the solid aluminosilicate material and the solid phase of the activator; Step S3, determining the thickness of the rich slurry on the aggregate surface based on the water-solid ratio and the target slump, and calculating the slurry requirement; Step S4, based on the ternary composition diagram of sodium silicate-sodium carbonate-activated MgO powder, a target performance experiment is set using the triangle single centroid method, and the optimal composition of sodium silicate-sodium carbonate-activated MgO is determined by the overlapping area that meets the target requirements in the coordinate transformation contour map; Step S5: Based on the aluminosilicate ternary composition diagram of the blast furnace slag-fly ash-burned clay-based pozzolan material, a target performance experiment is set, and the optimal composition of the blast furnace slag-fly ash-burned clay-based pozzolan material is determined by the overlapping areas that meet the target requirements in the coordinate transformation contour map; Step S6, completing the composition analysis and calculation of the blast furnace slag-based polymer concrete.

[0007] Optionally, in step S1, the optimal aggregate composition is the aggregate proportion corresponding to the maximum bulk density in the bulk density contour map.

[0008] Optionally, in step S2, the relationship between target strength and water-solid ratio and alkali-solid ratio is obtained by Figure 3 The quantitative relationship shown in the figure is determined by satisfying both the Borromi formula and GB / T 50476-2008 "Code for Durability Design of Concrete Structures", and for every 20 MPa increase in target strength, the blast furnace slag replacement ratio is reduced by 10%.

[0009] Optionally, in step S3, the quantitative relationship between the thickness of the rich slurry and the slump is obtained by Figure 4 The quantitative relationship shown is determined.

[0010] Optionally, in step S4, the sum of the mass percentages of sodium silicate, sodium carbonate and active MgO powder is 1, and the percentage of each component is ≥0; wherein the content of sodium silicate is 60-100%, sodium carbonate is 0-40%, and active MgO powder is 0-20%.

[0011] Optionally, in step S4, the target performance mainly includes early performance such as setting time and shrinkage.

[0012] Optionally, in step S5, the calcined clay-based pozzolan material is at least one of metakaolin and montmorillonite.

[0013] Optionally, in step S5, the sum of the mass percentages of blast furnace slag, fly ash and burned clay-based pozzolanic material is 1, and the percentage of each component is ≥0.

[0014] Optionally, in step S5, the target performance includes mechanical and durability properties such as compressive strength and impermeability.

[0015] The beneficial effects of the present invention are as follows: 1. The present invention uses the triangle single centroid method in the aggregate ternary composition diagram and the bulk density contour map ( Figure 1 、 Figure 2 ), accurately determine the optimal aggregate ratio, significantly improve aggregate density, reduce slurry demand, and reduce shrinkage risk.

[0016] 2. This invention specifies the water-to-solid ratio (blending water + activator water) and the alkali-to-solid ratio (mass of Na2O in the activator) based on the target strength, and links them to industry standards (such as the Borromi formula and GB / T 50476-2008) to ensure a balance between strength and durability.

[0017] 3. The present invention uses the quantitative relationship between slurry thickness and slump ( Figure 4 ), accurately calculate the slurry demand and ensure the performance of concrete construction.

[0018] 4. The present invention adopts the ternary composition diagram of sodium silicate-sodium carbonate-active MgO ( Figure 5-Figure 9 ), the optimal mix ratio is determined by the overlapping area of ​​the contour lines after coordinate transformation, and the setting time and shrinkage are optimized simultaneously (for example, in Example 1, the initial setting time is greater than 3 hours, the slump is not less than 150 mm, and the 3d autogenous shrinkage is not greater than 500 microstrains, etc.), solving the problems of rapid setting and large shrinkage of geopolymers.

[0019] 5. The present invention is based on the ternary composition diagram of slag-fly ash-burned clay (metakaolin / montmorillonite) ( Figure 9 ), adjust the ratio while meeting the slag replacement ratio constraint to achieve efficient resource utilization of industrial solid waste.

[0020] 6. The present invention uses step-by-step iterative optimization (if step (5) does not meet the slag ratio, return to step (2) for adjustment) and multi-performance contour line superposition ( Figure 6 、 Figure 7 etc.), avoid the blindness of traditional trial and error method and improve the efficiency and accuracy of ratio design. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which: Figure 1 The bulk density response contour diagram of the ternary composition of the aggregate provided by the present invention; Figure 2 The bulk density contour map of aggregates of different particle sizes provided in Example 1 of the present invention; Figure 3 A graph showing the relationship between the water-to-solid ratio, alkali-to-solid ratio and target strength of the blast furnace slag-based polymer concrete provided by the present invention; Figure 4 A graph showing the relationship between the slump and excess slurry thickness of the blast furnace slag-based polymer concrete provided by the present invention; Figure 5 A schematic diagram of the conversion relationship between the rectangular coordinate system and the ternary coordinate system provided by the present invention; Figure 6 The ternary composition of sodium silicate, sodium carbonate and active MgO provided in Example 1 of the present invention; contour map; wherein (a) is the contour map of initial setting time; (b) is the contour map of final setting time; Figure 7 The autogenous shrinkage contour map of the sodium silicate-sodium carbonate-active MgO ternary composition provided in Example 1 of the present invention; wherein (a) is the autogenous shrinkage contour map; (b) is the drying shrinkage contour map; Figure 8 The overlapping area of ​​the contour map that meets the target setting time and shrinkage requirements provided in Example 1 of the present invention; Figure 9 This is a contour diagram of the initial and final setting times of the ternary composition of the slag-fly ash-burned clay-based pozzolan material provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0025] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can refer to fixed connection, detachable connection, or integration; it can refer to mechanical connection; it can refer to direct connection or indirect connection through an intermediate medium; it can refer to internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0026] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0027] An embodiment of the present invention provides a method for designing the composition of blast furnace slag-based polymer concrete, comprising the following steps: Step S1, based on the aggregate ternary composition diagram, a bulk density experiment is set up using the triangle single centroid method, and the optimal aggregate composition is determined according to the bulk density contour map; Step S2, determining the water-to-solid ratio and the alkali-to-solid ratio based on the target strength; wherein the water in the water-to-solid ratio is the sum of the mass of the blending water and the water in the activator, the alkali in the alkali-to-solid ratio is the mass of the sodium oxide in the activator, and the solid phase in the water-to-solid ratio and the alkali-to-solid ratio is the sum of the mass of the solid aluminosilicate material and the solid phase of the activator; Step S3, setting the thickness of the rich slurry on the aggregate surface based on the water-solid ratio and the target slump, and calculating the slurry requirement; Step S4, based on the ternary composition diagram of sodium silicate-sodium carbonate-activated MgO powder, a target performance experiment is set using the triangle single centroid method, and the optimal composition of sodium silicate-sodium carbonate-activated MgO is determined by the overlapping area that meets the target requirements in the coordinate transformation contour map; Step S5: Based on the aluminosilicate ternary composition diagram of the blast furnace slag-fly ash-burned clay-based pozzolan material, a target performance experiment is set, and the optimal composition of the blast furnace slag-fly ash-burned clay-based pozzolan material is determined by the overlapping areas that meet the target requirements in the coordinate transformation contour map; Step S6, completing the composition analysis and calculation of the blast furnace slag-based polymer concrete.

[0028] In step S1, the optimal aggregate composition is the aggregate proportion corresponding to the maximum bulk density in the bulk density contour map.

[0029] In step S2, the relationship between target strength and water-solid ratio and alkali-solid ratio is obtained by Figure 3 The quantitative relationship shown in the figure is determined by satisfying both the Borromi formula and GB / T 50476-2008 "Code for Durability Design of Concrete Structures", and for every 20 MPa increase in target strength, the blast furnace slag replacement ratio is reduced by 10%.

[0030] In step S3, the quantitative relationship between the water-solid ratio, the thickness of the rich slurry and the slump is obtained by Figure 4 The quantitative relationship shown is determined.

[0031] In step S4, the sum of the mass percentages of sodium silicate, sodium carbonate and active MgO powder is 1, and the percentage of each component is ≥0; wherein the content of sodium silicate is 60-100%, the content of sodium carbonate is 0-40%, and the content of active MgO powder is 0-20%.

[0032] In step S4, the target performance mainly includes early performance such as setting time and shrinkage.

[0033] In step S5, the burnt clay-based pozzolan material is at least one of metakaolin and montmorillonite. The sum of the mass percentages of blast furnace slag, fly ash and burnt clay-based pozzolan material is 1, and the percentage of each component is ≥0.

[0034] In step S6, the quantitative relationship between the thickness of the rich slurry and the slump is obtained by Figure 4 The curve shown is determined.

[0035] In step S6, the target performance mainly includes mechanical and durability properties such as compressive strength and impermeability.

[0036] The composition design method of blast furnace slag-based polymer concrete provided by the present invention is described in detail below with reference to specific embodiments.

[0037] Example 1 The concrete materials required for a certain project A must meet the following requirements: initial setting time greater than 3 hours, final setting time greater than 5 hours; slump not less than 150mm; 3d autogenous shrinkage not greater than 500 microstrain; drying shrinkage not greater than 800 microstrain; strength not less than 30Mpa at 28d age.

[0038] The blast furnace slag-based polymer concrete composition design method provided in Example 1 includes the following steps: (1) Based on the aggregate ternary composition diagram (see Figure 1As shown in the figure), the triangle single centroid method is used to set up the bulk density experiment. The aggregate configuration table and bulk density test values ​​are shown in Table 1. Based on this configuration and test results, the bulk density contour map can be drawn (see Figure 2 As shown), the maximum bulk density is 2160kg / m 3 , appropriately reduce the amount of aggregate to retain the gap between aggregates, so as to obtain the optimal aggregate formulation of fine aggregate (particle size 0-5mm) 800kg / m 3 , coarse aggregate (particle size 5-10mm) 400kg / m 3 , fine aggregate (particle size 10-20mm) 800kg / m 3 .

[0039] Table 1 Aggregate ternary composition and corresponding bulk density results (2) Based on the relationship between target strength (30 MPa) and water-solid ratio and alkali-solid ratio (see Figure 3 As shown in the figure, the alkali-solid ratio is set to 0.04, and the water-solid ratio is ~0.4-~0.5, which meets the requirements of the Borromy formula and the "Code for Durability Design of Concrete Structures" (GB / T 50476-2008). To ensure the strength of concrete, it is recommended to reduce it by 0.01-0.03, so the water-solid ratio is set to 0.48. The replacement ratio of blast furnace slag is not more than 40%. (3) Based on the target slump and the quantitative relationship between excess slurry thickness and slump under different water-solid ratio conditions (see Figure 4 As shown in the figure), the thickness of the surplus slurry is calculated to be 55 μm. According to the specific surface area of ​​the aggregate (about 0.25 m 2 / kg) and the thickness of the surplus paste, the paste requirement of blast furnace slag-based polymer concrete is calculated to be 500kg / m 3 ; (4) Set the mass ratio of sodium silicate-sodium carbonate-active MgO to 0.5-1:0-0.4:0-0.2 (see Figure 4 As shown), we can get the contour map and the transformation relationship between the rectangular coordinate system and the ternary coordinate system (see Figure 5 As shown); 100% blast furnace slag was used as the aluminosilicate material, with a water-solid ratio of 0.48 and an alkali-solid ratio of 0.04. The coarse and fine aggregates determined in step (1) were used to prepare slag-based polymer concrete samples, and setting time and shrinkage experiments were set; the sodium silicate-sodium carbonate-active MgO ternary composition and related test results are shown in Table 2. Based on this configuration and test results, the initial setting and final setting time contour maps can be drawn (see Figure 6 (a) and (b)), autogenous shrinkage and drying shrinkage contour diagram (see Figure 7 The overlapping area that meets the target setting time and shrinkage requirements (see Figure 8 As shown in Figure 2, the optimal sodium silicate-sodium carbonate-active MgO ternary composition design is shown in Figure 2. The optimal sodium silicate-sodium carbonate-active MgO composition determined in this example is 0.55:0.4:0.05.

[0040] Table 2 The ternary composition of sodium silicate-sodium carbonate-active MgO and the corresponding setting time (5) Based on the aggregate gradation, water-solid ratio, alkali-solid ratio and optimal sodium silicate-sodium carbonate-active MgO ternary composition design determined in steps (1), (2) and (3), the ternary composition of blast furnace slag-fly ash-burned clay-based pozzolan material is set. Its constraint condition should meet step (2). Blast furnace slag-based polymer concrete is prepared and a compressive strength test experiment is set. The test results are shown in Table 3. Based on this configuration and test results, a compressive strength contour map can be drawn (see Figure 9 As shown). In the region that meets the compressive strength requirements, the group with a higher pozzolanic material content is selected as the optimal ternary composition design of blast furnace slag-fly ash-burned clay-based pozzolanic material. The composition of blast furnace slag-fly ash-burned clay-based pozzolanic material should meet the replacement ratio of blast furnace slag in step (2). Otherwise, return to step (2) and adjust until the composition result meets the replacement ratio.

[0041] Table 3 The ternary composition of blast furnace slag-fly ash-burned clay-based pozzolan materials and the corresponding setting time and compressive strength results (6) Based on the above design and calculation, the specific mix ratio of blast furnace slag-based geopolymer concrete is 200 kg blast furnace slag, 100 kg grade I fly ash, 200 kg metakaolin, 11 kg sodium silicate, 8 kg sodium carbonate, 1 kg active MgO powder, 240 kg water, 800 kg fine aggregate (particle size 0-5 mm), 400 kg coarse aggregate (particle size 5-10 mm), and 800 kg fine aggregate (particle size 10-20 mm). The mix ratio can then be reduced proportionally based on the measured bulk density. This mix ratio not only overcomes the common problems of rapid setting and high shrinkage of geopolymer concrete, but also ensures good workability and durability.

[0042] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0043] Furthermore, it should be noted that the scope of the methods and systems of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in reverse order, depending on the functions involved. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Furthermore, features described with reference to certain examples may be combined in other examples.

[0044] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for designing the composition of blast furnace slag-based polymer concrete, characterized in that: The following steps are involved: Step S1, based on the aggregate ternary composition diagram, a bulk density experiment is set up using the triangle single centroid method, and the optimal aggregate composition is determined according to the bulk density contour map; Step S2, determining the water-to-solid ratio and the alkali-to-solid ratio based on the target strength; wherein the water in the water-to-solid ratio is the sum of the mass of the blending water and the water in the activator, the alkali in the alkali-to-solid ratio is the mass of the sodium oxide in the activator, and the solid phase in the water-to-solid ratio and the alkali-to-solid ratio is the sum of the mass of the solid aluminosilicate material and the solid phase of the activator; Step S3, setting the thickness of the rich slurry on the aggregate surface based on the water-solid ratio and the target slump, and calculating the slurry requirement; Step S4, based on the ternary composition diagram of sodium silicate-sodium carbonate-activated MgO powder, a target performance experiment is set using the triangle single centroid method, and the optimal composition of sodium silicate-sodium carbonate-activated MgO is determined by the overlapping area that meets the target requirements in the coordinate transformation contour map; Step S5: Based on the aluminosilicate ternary composition diagram of the blast furnace slag-fly ash-burned clay-based pozzolan material, a target performance experiment is set, and the optimal composition of the blast furnace slag-fly ash-burned clay-based pozzolan material is determined by the overlapping areas that meet the target requirements in the coordinate transformation contour map; Step S6, completing the composition analysis and calculation of the blast furnace slag-based polymer concrete.

2. The method according to claim 1, characterized in that In step S1, the optimal aggregate composition is the aggregate proportion corresponding to the maximum bulk density in the bulk density contour map.

3. The method according to claim 1, characterized in that In step S2, the relationship between the target strength and the water-solid ratio and the alkali-solid ratio is determined by FIG3 , and must satisfy both the Borromee formula and GB / T 50476-2008 "Code for Durability Design of Concrete Structures". Furthermore, for every 20 MPa increase in the target strength, the blast furnace slag replacement ratio is reduced by 10%.

4. The method according to claim 1, wherein In step S3, the quantitative relationship between the water-to-solid ratio, the thickness of the rich slurry and the slump is determined by FIG4 .

5. The method according to claim 1, characterized in that In step S4, the sum of the mass percentages of sodium silicate, sodium carbonate and active MgO powder is 1, and the percentage of each component is ≥0; wherein the content of sodium silicate is 60-100%, the content of sodium carbonate is 0-40%, and the content of active MgO powder is 0-20%.

6. The method according to claim 1, characterized in that In step S4, the target performance mainly includes early performance such as setting time and shrinkage.

7. The method according to claim 1, characterized in that In step S5, the calcined clay-based pozzolan material is at least one of metakaolin and montmorillonite.

8. The method according to claim 1 or 6, characterized in that In step S5, the sum of the mass percentages of blast furnace slag, fly ash and burned clay-based pozzolanic material is 1, and the percentage of each component is ≥0.

9. The method according to claim 1, characterized in that In step S5, the target performance includes mechanical and durability properties such as compressive strength and impermeability.

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