Fabricated high-strength lightweight concrete wall

Abstract

The invention belongs to the field of prefabricated building materials, and provides an assembly type high-strength lightweight concrete wall which comprises a steel reinforcement framework, lightweight concrete and a supporting steel plate assembly, and the lightweight steel reinforcement framework and the lightweight concrete are prefabricated into a wall body unit with a parallelogram-shaped cross section; the steel reinforcement framework comprises parallelogram reinforcement rings, rectangular reinforcement rings and anchor bar steel wires which are connected, a supporting steel plate assembly is arranged on the inner side of the steel reinforcement framework and comprises a main steel plate, and a pair of diagonal bracing steel plates, namely an upper steel plate and a lower steel plate, is arranged on the main steel plate and connected with the main steel plate in an inserted mode. The top of the upper steel plate and the bottom of the lower steel plate are each provided with a set of auxiliary assembly ends, each auxiliary assembly end comprises a pair of angle steel plates, a plurality of pairs of side steel pipes and a plurality of positioning steel pipes, and the side steel pipes of the adjacent wall units are connected through inserting rods. The connecting structure is reasonable in design, simple in structure, high in assemblability, high in assembly flexibility, beneficial for reducing construction difficulty and improving construction quality and suitable for large-scale popularization.

Description

Technical Field

[0001] The invention belongs to the field of prefabricated building materials, and in particular relates to an assembled high-strength lightweight concrete wall. Background Art

[0002] Lightweight concrete, also known as foamed concrete, is a lightweight thermal insulation material containing a large number of closed pores. Lightweight concrete wall, lightweight concrete wall is a component of the solid wall system. The most important advantage of lightweight concrete wall is its extremely light weight and the resulting good thermal insulation performance, which can achieve fast, energy-saving and economical building structures. By prefabricating the lightweight concrete wall panels required for the building, the construction efficiency can be effectively improved and the construction period can be shortened.

[0003] Existing prefabricated lightweight concrete wall panels mostly adopt a whole-surface structure, and the area of ​​the front and back surfaces is mostly about 1.8X3.5m, such as the crack-resistant prefabricated concrete panel disclosed in CN213710096U, the prefabricated thermal insulation composite panel disclosed in CN102477778A, and the prefabricated concrete panel disclosed in CN215290221U. The use of such concrete panels has high requirements for the space and equipment of the production workshop, and will also cost a lot in terms of transportation; in addition, even if the larger volume of concrete wall panels saves time in assembly operations compared with traditional casting, the construction difficulty and risk factor are also greater, and the requirements for the construction site are also higher; secondly, the joints between the prefabricated walls are mostly vertical surfaces, and the sealing performance needs to be improved. Summary of the invention

[0004] In view of the technical problems existing in the actual assembly of the above-mentioned prefabricated walls, the present invention proposes an assembled high-strength lightweight concrete wall with reasonable design, simple structure, strong assemblability, high assembly flexibility, which is conducive to reducing construction difficulty and improving construction quality.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is that the present invention provides an assembled high-strength lightweight concrete wall, including a steel skeleton and lightweight concrete, the steel skeleton includes a plurality of anchor steel wires, the lightweight steel skeleton and the lightweight concrete are prefabricated into a wall unit with a parallelogram cross section, the thickness of the wall unit is 20 to 30 cm and the height is greater than 330 cm, the steel skeleton includes a plurality of parallelogram reinforcement rings spaced apart along the length direction of the wall unit, the steel skeleton also includes a plurality of rectangular reinforcement rings spaced apart along the thickness direction of the wall unit, the rectangular reinforcement ring is located on the inner side of the parallelogram reinforcement ring and is connected to all the parallelogram reinforcement rings by anchor steel wires. A supporting steel plate assembly is provided on the inner side of the steel frame, and the supporting steel plate assembly includes a main steel plate, and a pair of diagonal steel plates plugged therein are provided on the main steel plate, and the upper steel plate and the lower steel plate are respectively provided. The plate surface of the diagonal steel plate and the plate surface of the main steel plate are respectively located on the planes where the two diagonals of the wall unit are located. A group of auxiliary assembly end heads are provided on the top of the upper steel plate and the bottom of the lower steel plate. The auxiliary assembly end heads include a pair of angle steel plates distributed on both sides of the main steel plate and located on the inner side of the steel frame, and a plurality of pairs of side steel pipes and a plurality of positioning steel pipes are provided on the angle steel plates, and one end of the side steel pipe and one end of the positioning steel pipe are both flush with the surface of the wall unit, and the side steel pipes of adjacent wall units are connected by plug rods.

[0006] Preferably, the main steel plate, the upper steel plate and the lower steel plate are each provided with a plurality of teeth that cooperate with the steel bar skeleton.

[0007] Preferably, the side steel pipe is arranged on one side of the slope facing the wall unit, there are at least three pairs of side steel pipes on the angle steel plate and they are spaced apart along the length direction of the wall unit, one end of the side steel pipe facing the positioning socket is a blocked end, and multiple positioning steel pipes are distributed in a triangular shape on the top surface of the angle steel plate, and one end of the positioning steel pipe facing the positioning socket is a blocked end.

[0008] Preferably, the cross section of the angle steel plate is in the shape of a “>”, and a positioning socket is provided on the side of the angle steel plate which is in surface contact with the main steel plate, and the positioning socket is used for plugging with the upper steel plate and the lower steel plate.

[0009] Preferably, the diagonal bracing steel plate comprises a parallelogram-shaped butt joint plate, the butt joint plate of the upper steel plate is connected to the butt joint plate of the lower steel plate by bolts, the butt joint plate is provided with a diagonal bracing plate perpendicular thereto, the diagonal bracing plate is provided with an oblique insertion seam penetrating the butt joint plate, and the main steel plate is provided with a main insertion seam cooperating with the oblique insertion seam.

[0010] Preferably, the vertical plane where the main steel plate is located is located on the obtuse diagonal line of the wall unit, and the plane where the obtuse diagonal line is located is perpendicular to the wall surface of the wall unit.

[0011] Preferably, the main steel plate and the diagonal bracing steel plate are both provided with a plurality of long strip-shaped weight-reducing holes.

[0012] Preferably, the lightweight concrete comprises silicate cement concrete and external additives, wherein the external additives comprise mineral admixtures, retarders, expansion agents, air entraining agents, polypropylene fibers, anti-carbonization agents and polycarboxylate water reducers prepared from silane-modified polyethers.

[0013] Preferably, the water-to-cement ratio of the Portland cement concrete is 0.40-0.50.

[0014] Preferably, the anti-carbonization agent is a mixture of calcium hydroxide and calcium carbonate with a mixing ratio of 5:1, and the amount of the mineral admixture is not more than 40%.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are:

[0016] 1. The present invention provides an assembled high-strength lightweight concrete wall, which uses multiple wall units to form the entire wall surface, breaking the whole into parts, can reduce the production space requirements and transportation costs, and can reduce the difficulty and danger in the assembly process, while also having high support strength and good assembly sealing. The present invention has a reasonable design, simple structure, strong assemblability, high assembly flexibility, is conducive to reducing construction difficulty and improving construction quality, and is suitable for large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 An axonometric view of an assembled high-strength lightweight concrete wall provided in an embodiment;

[0019] Figure 2 A front view of an assembled high-strength lightweight concrete wall provided in an embodiment;

[0020] Figure 3 A front view of a steel reinforcement skeleton and a supporting steel plate assembly provided in an embodiment;

[0021] Figure 4 An axonometric view of a steel reinforcement skeleton and supporting steel plate assembly provided for an embodiment;

[0022] Figure 5 A top view of a steel reinforcement skeleton and a supporting steel plate assembly provided in an embodiment;

[0023] Figure 6 An exploded view of a support steel plate assembly provided for an embodiment;

[0024] Figure 7 A combined diagram of a support steel plate assembly provided for an embodiment;

[0025] Figure 8 A front view of an upper steel plate provided in an embodiment;

[0026] In the above figures, 1. steel bar skeleton; 11. parallelogram reinforcement ring; 12. rectangular reinforcement ring; 2. lightweight concrete; 3. wall unit; 4. supporting steel plate assembly; 41. main steel plate; 411. main insertion seam; 42. diagonal bracing steel plate; 421. upper steel plate; 422. lower steel plate; 423. butt plate; 424. diagonal bracing plate; 425. diagonal insertion seam; 43. auxiliary assembly end; 431. angle steel plate; 432. side steel pipe; 433. positioning steel pipe; 434. positioning socket; 44. tooth mouth; 45. weight reduction hole. DETAILED DESCRIPTION

[0027] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear below, they only indicate that the upper, lower, left and right directions are consistent with the accompanying drawings themselves, and do not limit the structure.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0029] Examples, such as Figure 1 As shown in FIG8 , the present invention provides an assembled high-strength lightweight concrete wall, comprising a steel skeleton 1 and lightweight concrete 2, wherein the steel skeleton 1 comprises a plurality of anchor steel wires, and the lightweight steel skeleton 1 and the lightweight concrete 2 are prefabricated into a wall unit 3 with a parallelogram cross section, the wall unit 3 has a thickness of 20 to 30 cm and a height of more than 330 cm, and a plurality of wall units 3 can be spliced ​​in sequence on the left and right sides to form a wall with uniform thickness, and the two sides of the wall can be formed with concrete wall units 3 with triangular cross sections, and the basic design of the triangular concrete wall unit 3 is similar to the parallelogram wall unit 3 of the present invention, and most of the supporting force inside the building is supported by columns and beams.

[0030] In order to improve the actual utilization rate of the wall unit 3, the steel frame 1 provided by the present invention includes a plurality of parallelogram reinforcement rings 11 spaced apart along the length direction of the wall unit 3, the steel frame 1 also includes a plurality of rectangular reinforcement rings 12 spaced apart along the thickness direction of the wall unit 3, the rectangular reinforcement rings 12 are located on the inner side of the parallelogram reinforcement rings 11 and are connected to all the parallelogram reinforcement rings 11 through anchor steel wires, a supporting steel plate assembly 4 is arranged on the inner side of the steel frame 1, the supporting steel plate assembly 4 includes a main steel plate 41, a pair of diagonal bracing steel plates 42 plugged therein are arranged on the main steel plate 41, and the upper steel plate 421 and the lower steel plate 422 are respectively Plate 422, the plate surface of the diagonal bracing steel plate 42 and the plate surface of the main steel plate 41 are respectively located on the planes where the two diagonals of the wall unit 3 are located, and a group of auxiliary assembly end heads 43 are provided at the top of the upper steel plate 421 and the bottom of the lower steel plate 422. The auxiliary assembly end heads 43 include a pair of angle steel plates 431 distributed on both sides of the main steel plate 41 and located on the inner side of the steel frame 1, and multiple pairs of side steel pipes 432 and multiple positioning steel pipes 433 are provided on the angle steel plates 431. One end of the side steel pipe 432 and one end of the positioning steel pipe 433 are flush with the surface of the wall unit 3, and the side steel pipes 432 of adjacent wall units 3 are connected by plug rods.

[0031] In the wall unit 3 provided by the present invention, the main steel plate 41 and the diagonal bracing steel plate 42 provide internal support for the steel skeleton 1, and the auxiliary assembly end 43 serves as the positioning parts at both ends of the system and the basis for connection with other building structures. The prefabrication workshop pours lightweight concrete 2 in the frame after the steel skeleton 1 and the supporting steel plate assembly 4 are finalized, and an effective wall unit 3 can be formed through the curing step. The wall unit 3 after demoulding has connection holes reserved for the positioning steel pipe 433 on its two end faces, and the side steel pipe 432 has reserved connection holes on the two inclined sides of the wall unit 3, that is, the assembly surface of the adjacent wall unit 3. The assembly surface of the side of the wall unit 3 is positioned by inserting rods, and the top surface and the ground of the wall unit 3 are assembled with the positioning steel bars reserved in the building. During the hoisting process of the wall unit 3, the U-shaped claw / U-shaped rod can be inserted into the side steel pipe 432, and the hoisting and transportation can be completed with the steel rope and the hoisting equipment. The connection holes on the wall unit 3 provided by the present invention are mostly concealed designs, which can not only meet the connection requirements of the assembly nodes, but also ensure the prefabrication quality of the product, save the occupied volume, and to a certain extent help reduce transportation costs.

[0032] The present invention adopts a plurality of wall units 3 to form the entire wall surface, which can reduce the production space requirements and transportation costs. Compared with the whole wall as a single piece for hoisting and transportation, the difficulty and danger of the assembly operation are significantly reduced. At the same time, the design of breaking the whole into parts can be flexibly installed according to the construction conditions on site, reducing the assembly error between the on-site assembly conditions and design conditions and the wall unit 3, which is conducive to improving the construction accuracy and quality, and provides a new construction plan for specific construction operations. In addition, the auxiliary assembly end 43, the main steel plate 41, the upper steel plate 421 and the lower steel plate 422 provide a good support foundation for the steel skeleton 1, which is conducive to improving the structural strength of the wall unit 3. Further, on the basis of meeting the support strength of the wall after assembly, the adjacent wall units 3 adopt inclined docking surfaces, which can increase the difficulty of wind flow on both sides of the wall and improve the assembly sealing of the wall.

[0033] In order to improve the connection reliability between the steel skeleton 1 and the supporting steel plate assembly 4, the main steel plate 41, the upper steel plate 421 and the lower steel plate 422 provided by the present invention are all provided with a plurality of teeth 44 that cooperate with the steel skeleton 1. The steel skeleton 1 at each position is positioned by the teeth 44, and each intersection node is fixed by the anchor steel wire, thereby ensuring the reliability and strength of the internal system of the lightweight concrete 2.

[0034] In order to improve the assembly performance of the wall unit 3, the side steel pipe 432 provided by the present invention is arranged on the side of the slope facing the wall unit 3, there are at least 3 pairs of side steel pipes 432 on the angle steel plate 431 and they are spaced apart along the length direction of the wall unit 3, the end of the side steel pipe 432 facing the positioning socket 434 is a blocked end, and a plurality of positioning steel pipes 433 are distributed in a triangular shape on the top surface of the angle steel plate 431, and the end of the positioning steel pipe 433 facing the positioning socket 434 is a blocked end. Among them, the two angle steel plates 431 of the same auxiliary assembly end 43 can establish a relatively complete end face, which not only plays the role of supporting the main steel plate 41 and the diagonal bracing steel plate 42, but also provides accurate orientation and connection nodes for the side steel pipe 432 and the positioning steel pipe 433, which is conducive to ensuring that the final prefabricated wall unit 3 has a uniformly regulated reserved hole, and is conducive to improving the assembly quality of adjacent wall units 3.

[0035] In order to ensure that the angle steel plate 431 has sufficient structural strength, the cross section of the angle steel plate 431 provided by the present invention is in the shape of a “>”. One end of the angle steel plate 431 facing the butt joint of the upper steel plate 421 and the lower steel plate 422 is open for the lightweight concrete 2 to flow and fill, and the other end of the angle steel plate 431 is a blocking surface, serving as a support plane for positioning the steel pipe 433. Furthermore, the angle steel plate 431 is provided with a positioning socket 434 on the side where it is in contact with the main steel plate 41. The positioning socket 434 is used to be plugged with the upper steel plate 421 and the lower steel plate 422, thereby improving the accuracy and reliability of the position of the angle steel plate 431 inside the steel frame 1, thereby ensuring the quality of the prefabricated product.

[0036] In order to ensure that the diagonal brace steel plate 42 has sufficient structural strength, the diagonal brace steel plate 42 provided by the present invention includes a parallelogram-shaped butt joint plate 423, the butt joint plate 423 of the upper steel plate 421 is connected to the butt joint plate 423 of the lower steel plate 422 by bolts, and a diagonal brace plate 424 perpendicular to it is provided on the butt joint plate 423, and an oblique insertion slit 425 penetrating the butt joint plate 423 is provided on the diagonal brace plate 424, and a main insertion slit 411 cooperating with the oblique insertion slit 425 is provided on the main steel plate 41. Among them, the two diagonal brace steel plates 42 are matched with the length span of the main steel plate 41 by butt joint, and the steel plate structure formed after the three are plugged is a three-dimensional cross structure, especially matching the parallelogram characteristics of the wall unit 3, showing a stable support system, ensuring the support strength of the steel plate support system. At the same time, a prefabricated wall unit 3 uses two diagonal brace steel plates 42, which have a high degree of interchangeability and can reduce production costs, while the main steel plate 41 itself is a single flat plate design, and the structure is relatively simple, which is easy to manufacture.

[0037] In order to improve the structural strength of the wall unit 3, the vertical plane where the main steel plate 41 provided by the present invention is located is located on the obtuse diagonal line of the wall unit 3, and the plane where the obtuse diagonal line is located is perpendicular to the wall surface of the wall unit 3. In this way, the main steel plate 41 and the diagonal bracing steel plate 42 can correspond to the position where the stress is concentrated, especially the main steel plate 41 can form a three-axis support with the building beam, the ground and the prefabricated wall, with a high support strength angle and a long service life.

[0038] In order to reduce the weight of the wall unit 3 , the present invention provides a plurality of long strip-shaped weight-reducing holes 45 on both the main steel plate 41 and the diagonal bracing steel plate 42 .

[0039] In order to improve the quality of the wall unit 3, from the material aspect, the lightweight concrete 2 provided by the present invention includes silicate cement concrete and external additives, and the external additives include mineral admixtures, retarders, expansion agents, air entraining agents, polypropylene fibers, anti-carbonization agents and polycarboxylic acid water reducers prepared from silane-modified polyethers. Among them, the mineral admixture adopts ground mineral powder / slag, which can improve the impermeability and durability, and the active ingredients in the mineral admixture participate in the cement hydration reaction, promote the formation of cement hydration products, form a dense gel, and improve the impermeability of cement concrete; the retarder can delay the coagulation and hardening process of cement paste; the anti-carbonation agent can cooperate with the mineral admixture to improve the anti-carbonation performance of lightweight concrete 2; the expansion agent and air entraining agent can promote the generation of stable bubbles, form a microscopic pore structure, reduce the density of concrete, and increase the porosity of concrete, and the expansion agent and air entraining agent can also reduce the possibility of carbon dioxide entering, and improve the anti-carbonation performance of lightweight concrete 2; polypropylene fiber can improve the compressive strength of lightweight concrete 2; the polycarboxylic acid water reducer prepared by silane-modified polyether can improve the anti-adhesion property of concrete, so that it has a better flow filling effect in the prefabricated system, thereby ensuring the quality of the wall unit 3.

[0040] In order to improve the durability of the wall unit 3, the water-cement ratio of the silicate cement concrete provided by the present invention is 0.40-0.50. The lightweight concrete 2 designed with this water-cement ratio has better performance in carbonation resistance in the later stage, which is beneficial to ensure the quality and actual life of the building.

[0041] Furthermore, the anti-carbonation agent provided by the present invention is a mixture of calcium hydroxide and calcium carbonate with a mixing ratio of 5:1, and the amount of the mineral admixture is not more than 40%. When the amount of the mineral admixture exceeds 40%, the anti-carbonation property of the prefabricated lightweight concrete 2 will be reduced; by adding calcium hydroxide to the components of the lightweight concrete 2, it can directly improve the anti-carbonation property of the concrete, and the calcium carbonate mixed with it can also increase the diffusivity of calcium hydroxide in the process of mixing with other additives, and play a certain expansion role, thereby improving the stability of bubbles generated inside the prefabricated concrete.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. An assembled high-strength lightweight concrete wall, comprising a steel skeleton and lightweight concrete, wherein the steel skeleton comprises a plurality of anchor steel wires, characterized in that: The lightweight steel skeleton and lightweight concrete are prefabricated into a wall unit with a parallelogram cross section, the wall unit has a thickness of 20 to 30 cm and a height of more than 330 cm, the steel skeleton includes a plurality of parallelogram reinforcement rings spaced apart along the length direction of the wall unit, the steel skeleton also includes a plurality of rectangular reinforcement rings spaced apart along the thickness direction of the wall unit, the rectangular reinforcement rings are located on the inner side of the parallelogram reinforcement rings and are connected to all parallelogram reinforcement rings through anchor steel wires, a support steel plate assembly is arranged on the inner side of the steel skeleton, the support steel plate assembly includes a main steel plate, The main steel plate is provided with a pair of diagonal bracing steel plates plugged therein, which are an upper steel plate and a lower steel plate respectively. The plate surface of the diagonal bracing steel plate and the plate surface of the main steel plate are respectively located on the planes where the two diagonals of the wall unit are located. The top of the upper steel plate and the bottom of the lower steel plate are each provided with a group of auxiliary assembly ends. The auxiliary assembly ends include a pair of angle steel plates distributed on both sides of the main steel plate and located on the inner side of the steel frame. Multiple pairs of side steel pipes and multiple positioning steel pipes are provided on the angle steel plates. One end of the side steel pipe and one end of the positioning steel pipe are both flush with the surface of the wall unit, and the side steel pipes of adjacent wall units are connected by an insertion rod.

2. The assembled high-strength lightweight concrete wall according to claim 1, characterized in that: The main steel plate, the upper steel plate and the lower steel plate are all provided with a plurality of teeth which match with the steel bar skeleton.

3. The assembled high-strength lightweight concrete wall according to claim 2, characterized in that: The side steel pipe is arranged on one side of the slope facing the wall unit, there are at least three pairs of side steel pipes on the angle steel plate and they are spaced apart along the length direction of the wall unit, one end of the side steel pipe facing the positioning socket is a blocked end, and multiple positioning steel pipes are distributed in a triangular shape on the top surface of the angle steel plate, and one end of the positioning steel pipe facing the positioning socket is a blocked end.

4. The assembled high-strength lightweight concrete wall according to claim 3, characterized in that: The cross section of the angle steel plate is in the shape of a ">"; a positioning socket is provided on one side of the angle steel plate which is in contact with the main steel plate surface, and the positioning socket is used for plugging with the upper steel plate and the lower steel plate.

5. The assembled high-strength lightweight concrete wall according to claim 1, characterized in that: The diagonal bracing steel plate comprises a parallelogram-shaped butt joint plate, the butt joint plate of the upper steel plate is connected to the butt joint plate of the lower steel plate by bolts, the butt joint plate is provided with a diagonal bracing plate perpendicular thereto, the diagonal bracing plate is provided with an oblique insertion seam penetrating the butt joint plate, and the main steel plate is provided with a main insertion seam cooperating with the oblique insertion seam.

6. The assembled high-strength lightweight concrete wall according to claim 1, characterized in that: The vertical plane where the main steel plate is located is located on the obtuse diagonal line of the wall unit, and the plane where the obtuse diagonal line is located is perpendicular to the wall surface of the wall unit.

7. The assembled high-strength lightweight concrete wall according to claim 1, characterized in that: The main steel plate and the diagonal bracing steel plate are both provided with a plurality of long strip-shaped weight-reducing holes.

8. The assembled high-strength lightweight concrete wall according to claim 1, characterized in that: The lightweight concrete comprises silicate cement concrete and external additives, wherein the external additives comprise mineral admixtures, a retarder, an expansion agent, an air entraining agent, polypropylene fiber, an anti-carbonization agent and a polycarboxylate water-reducing agent prepared from silane-modified polyether.

9. The assembled high-strength lightweight concrete wall according to claim 8, characterized in that: The water-to-binder ratio of the Portland cement concrete is 0.40-0.

50.

10. The assembled high-strength lightweight concrete wall according to claim 9, characterized in that: The anti-carbonization agent is a mixture of calcium hydroxide and calcium carbonate with a mixing ratio of 5:1, and the amount of the mineral admixture is not more than 40%.

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