Two-graded rockfill concrete and construction method thereof

Abstract

The present disclosure provides a two-graded rockfill concrete and its construction method. The two-graded rockfill concrete comprises a two-graded rockfill body composed of medium-sized rock aggregate with a particle size of 150 to 350 mm and large-sized rock aggregate with a particle size greater than 350 mm, and high-performance self-compacting concrete that fills the voids within the rockfill body. The construction method includes: preparing the medium-sized rock aggregate and the large-sized rock aggregate; erecting a formwork or its alternative, and simultaneously feeding the medium-sized rock aggregate and the large-sized rock aggregate into a casting bin to a set height through either horizontal or vertical feeding, thereby forming a two-graded rockfill body with a rockfill ratio of 65 to 70%; and pouring high-performance self-compacting concrete to flow and fill the voids within the two-graded rockfill body to form a complete two-graded rockfill concrete. The present disclosure can improve the rockfill ratio of the rockfill concrete, reduce cement usage and hydration heat, and has the advantages of energy conservation, environmental protection, and economy. The rockfill bin method, which combines vertical and horizontal feeding, ensures the efficiency of rockfill concrete construction.

Description

Technical Field

[0001] The present disclosure relates to a concrete material and a construction method thereof, and in particular to a two-graded rockfill concrete and a construction method thereof. Background Art

[0002] Rockfill concrete is a new type of mass concrete originally developed in China with independent intellectual property rights (Jin Feng, An Xuehui. Construction Method for Rockfill Concrete Dams, ZL03102674.5). Existing rockfill concrete consists of a rockfill mass formed by the natural accumulation of rocks larger than 300mm in diameter, with high-performance self-compacting concrete filling the voids within the rockfill mass. Common construction methods for rockfill concrete include the conventional rockfill concrete method (Jin Feng, An Xuehui, Ohara Takayuki, et al. Conventional rockfill concrete construction method, ZL200710100315.3), in which rocks are first piled to form a rockfill mass and then self-compacting concrete is poured; and the riprap rockfill concrete method (An Xuehui, Jin Feng, Ohara Takayuki, et al. Riprap rockfill concrete construction method, ZL200710121791.3), in which rocks are first poured into the self-compacting concrete mass and then thrown into the mass to form a rockfill mass. Both methods require no vibration or compaction during construction, and the rockfill ratio can reach 55% to 60%. Compared to conventional large-volume concrete, rockfill concrete fully utilizes local stone, requires less cement, has a low hydration heat, and eliminates the need for complex temperature control measures. It offers advantages such as energy conservation, environmental protection, and cost-effectiveness.

[0003] In the two decades since its invention in 2003, rockfill concrete technology has developed rapidly, with many innovations in materials, construction techniques, and emerging applications. For example, the invention of a technology for applying rockfill concrete underwater by adding a protective agent to the water (Jin Feng, Zhou Hu, et al. A method for underwater rockfill concrete construction, CN201110117387.5), and a technology for reinforcing existing rockfill dams by setting rockfill strips and grouting rockfill concrete (Xu Yanjie, Jin Feng, et al. A rockfill dam based on rockfill concrete). reinforcement method, ZL201310116483.7), invented reinforced rockfill concrete and its construction method to improve the tensile toughness of rockfill concrete (Jin Feng, Nie Jianguo et al. A reinforced rockfill concrete structure and its construction method, ZL202010608113.5), and screened and piled construction waste to form a rockfill body to further improve its environmental friendliness (Ji Jingan, Chen Yiqun et al. A recycled rockfill concrete, CN202210844850.4), etc.

[0004] In recent years, the development of rockfill concrete has entered a new stage, and its engineering application will gradually be extended to high dam construction. On the basis of ensuring material performance, further improving the rockfill rate to reduce cement consumption and reduce hydration heat is one of the current research hotspots of rockfill concrete, and further improvement is still needed. Summary of the Invention

[0005] This application is based on the inventor's discovery and understanding of the following facts and problems:

[0006] Existing rockfill concrete uses ungraded rockfill bodies, and the rockfill ratio in rockfill concrete projects is less than 60%. The rockfill is often delivered into the warehouse by dump trucks. Facing the steep slope of the high dam, it is difficult to build a road for dump trucks to access the dam, resulting in low construction efficiency.

[0007] To this end, the first aspect of the present disclosure proposes a two-graded rockfill concrete. Compared with conventional rockfill concrete, the two-graded rockfill concrete can increase the rockfill rate by at least 5%, fully utilize the stone, reduce the cement content of conventional rockfill concrete, further reduce the total amount of hydration heat, and improve the environmental protection and economic efficiency of the rockfill concrete.

[0008] To achieve the above objectives, the present disclosure provides, in a first aspect, a two-graded rockfill concrete, comprising a two-graded rockfill body disposed in a casting bin and high-performance self-compacting concrete filling voids within the two-graded rockfill body. The two-graded rockfill body is composed of medium-sized rock aggregate with a particle size of 150 mm to 350 mm and large-sized rock aggregate with a particle size greater than 350 mm.

[0009] Optionally, the medium stone aggregate and the large stone aggregate are fed into the casting bin at the same time, and the medium stone aggregate and the large stone aggregate are fed into the casting bin by either or both of horizontal and vertical feeding.

[0010] Optionally, the ratio of the total volume of the medium stone aggregate to the total volume of the two-graded rockfill body is defined as the medium stone ratio α, and the ratio of the total volume of the two-graded rockfill body to the total volume of the two-graded rockfill concrete is defined as the rockfill ratio r, and the rockfill ratio r is a function of the medium stone ratio α and the thickness of the casting bin.

[0011] Optionally, the rockfill rate r shows a parabolic variation law of first increasing and then decreasing as the proportion of medium rocks α increases, specifically:

[0012] When the proportion of the medium-sized rocks is α=0% to 30%, the rock-filling ratio r is 55% to 65%, and the rock-filling ratio r is positively correlated with the thickness of the casting bin;

[0013] When the proportion of the medium-sized rocks α=30% to 70%, the rock-filling ratio r is 65% to 70%, and the positive correlation between the rock-filling ratio r and the thickness of the casting bin decreases with the increase of the proportion of the medium-sized rocks;

[0014] When the proportion of the medium-sized rocks is α=40% to 60%, the rockfill ratio r reaches the maximum rockfill ratio of the two-graded rockfill concrete, i.e., 67% to 70%;

[0015] When the proportion of the medium-sized rocks α=70% to 100%, the rock-filling ratio r is 62% to 63%, and the rock-filling ratio r is weakly correlated with the thickness of the casting bin.

[0016] Optionally, in engineering applications, the value range of the proportion of medium-sized rocks α is 30% to 70%, and the rockfill rate r is 65% to 70%.

[0017] Optionally, the coarse aggregate particle size of the high-performance self-compacting concrete is 10mm-16mm, the slump is 270mm-290mm, the expansion is 650mm-800mm, the V-funnel passage time is 4s-15s, and the self-compacting performance stability should be greater than or equal to 1 hour.

[0018] Optionally, the thickness of the casting bin is 1.0m to 4.0m.

[0019] A second aspect of the present disclosure provides a construction method for the above-mentioned two-graded rockfill concrete, comprising the following steps:

[0020] (1) Prepare the medium block aggregate and the large block aggregate, and formulate the high performance self-compacting concrete. Assume that the total mass of the medium block aggregate entering the warehouse is M 中 , should meet the following requirements:

[0021] M 中 =α·r·ρ·V

[0022] Wherein, ρ is the density of the medium stone aggregate, V is the volume of the casting bin, α is the proportion of medium stone, that is, the ratio of the total volume of the medium stone aggregate to the total volume of the two-graded rockfill body, and r is the rockfill ratio, that is, the ratio of the total volume of the two-graded rockfill body to the total volume of the two-graded rockfill concrete;

[0023] (2) supporting the formwork of the casting bin or its substitute, and then simultaneously feeding the large stone aggregate and the medium stone aggregate into the casting bin so that the two-graded rock pile in the casting bin reaches a set height, wherein the medium stone aggregate and the large stone aggregate are fed into the casting bin by either horizontal feeding or vertical feeding, or both;

[0024] (3) pouring the high-performance self-compacting concrete so that it flows and fills the voids in the two-graded rockfill body until it reaches the designed height of the top of the silo surface, thereby forming the two-graded rockfill concrete.

[0025] Optionally, the tool used for the vertical warehousing method is a tower crane or its substitute.

[0026] Optionally, the tool used for the horizontal warehousing method is a belt conveyor or its substitute.

[0027] The present disclosure has the following features and beneficial effects:

[0028] 1. By rationally designing the volume ratio of medium and large aggregates, the rockfill ratio of rockfill concrete can be increased by at least 5%, and up to 15%. This increased rockfill ratio reduces the amount of self-compacting concrete, which in turn reduces cement usage and reduces the overall hydration heat of rockfill concrete, improving its environmental and economic performance.

[0029] 2. A construction method developed for two-graded rockfill concrete, combining horizontal and vertical loading, ensures efficient construction of the concrete. Furthermore, this method offers advantages for high-dam construction, further promoting its application in high-dam construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic structural diagram of a two-graded rockfill concrete provided in an embodiment of the present disclosure.

[0031] Figures 2 to 5 A schematic diagram of the steps of a construction method of two-graded rockfill concrete provided in an embodiment of the present disclosure, wherein: Figure 2 A schematic diagram of the supporting formwork. Figure 3 Schematic diagram of horizontally entering medium-sized stone aggregates and vertically entering large-sized stone aggregates. Figure 4 This is a schematic diagram of the two-level rockfill body that has been put into storage. Figure 5 Schematic diagram of pouring high-performance self-compacting concrete into a two-graded rockfill mass.

[0032] Reference numerals:

[0033] 1: Medium stone aggregate; 2: Large stone aggregate; 3: High-performance self-compacting concrete; 4: Formwork or its substitute; 5: Tower crane or its substitute; 6: Belt conveyor or its substitute DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of this application more clear, the following is a further detailed description of this application in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0035] On the contrary, this application covers any alternatives, modifications, equivalents, and solutions made within the spirit and scope of this application as defined by the claims. Furthermore, to facilitate a better understanding of this application, certain specific details are described in detail below in the detailed description of this application. Those skilled in the art will be able to fully understand this application without these details.

[0036] like Figure 1As shown, a two-graded rockfill concrete provided by an embodiment of the first aspect of the present disclosure includes a two-graded rockfill body disposed within a casting bin (not shown) and high-performance self-compacting concrete 3 filling the voids within the two-graded rockfill body. The two-graded rockfill body is composed of medium-sized rock aggregate 1 with a particle size of 150 mm to 350 mm and large-sized rock aggregate 2 with a particle size greater than 350 mm. The medium-sized rock aggregate 1 should account for 30% to 70% of the total volume of the two-graded rockfill body, resulting in a rockfill ratio of 65% to 70%.

[0037] In some embodiments, a casting bin is formed by supporting a formwork or its substitute 4 at a designated position, and the medium-sized stone aggregate 1 and the large-sized stone aggregate 2 are simultaneously fed into the casting bin, and the medium-sized stone aggregate 1 and the large-sized stone aggregate 2 are fed into the casting bin in a manner of horizontal entry or vertical entry, or both. It should be noted that horizontal entry refers to the process in which the stone aggregate is transported to the top of the casting bin by a horizontal transport machine (such as a belt conveyor or its substitute) in a horizontal manner before being put into the casting bin, and vertical entry refers to the process in which the stone aggregate is transported to the top of the casting bin by a vertical transport machine (such as a tower crane or its substitute) in a vertical manner before being put into the casting bin. The flexible coordination of horizontal entry and vertical entry ensures the construction efficiency of two-graded rockfill concrete. Furthermore, the problem of difficulty in constructing a road for dump trucks to access the dam on the steep slope of a high dam can be solved, making two-graded rockfill concrete advantageous for high dam construction and promoting the development of rockfill concrete high dam applications.

[0038] In some embodiments, the ratio of the total volume of the medium-sized stone aggregate 1 to the total volume of the two-graded rockfill body is defined as the medium-sized stone ratio α, which reflects the rockfill particle size distribution. The ratio of the total volume of the two-graded rockfill body to the total volume of the two-graded rockfill concrete is defined as the rockfill ratio r, which is a function of the medium-sized stone ratio α and the thickness h of the casting bin (i.e., the height dimension of the casting bin).

[0039] Furthermore, the rockfill rate r shows a parabolic change law of first increasing and then decreasing with the increase of the proportion of medium-sized rocks α, specifically:

[0040] When the proportion of the medium-sized rocks is α=0% to 30%, the rock-filling ratio r is 55% to 65%, and the rock-filling ratio r is positively correlated with the thickness h of the casting bin;

[0041] When the proportion of medium-sized rocks α=30% to 70%, the rockfill ratio r is 65% to 70%, and the positive correlation between the rockfill ratio r and the thickness h of the casting bin decreases with the increase of the proportion of medium-sized rocks;

[0042] When the proportion of the medium-sized rocks is α=40% to 60%, the rockfill ratio r reaches the maximum rockfill ratio of the two-graded rockfill concrete, i.e., 67% to 70%;

[0043] When the proportion of the medium-sized rocks α=70% to 100%, the rock-filling ratio r is 62% to 63%, and the rock-filling ratio r is weakly correlated with the thickness h of the casting bin.

[0044] Furthermore, based on the above principles, in engineering applications, the range of the medium rock fraction α is 30% to 70%, and the rockfill ratio r is 65% to 70%. This embodiment can increase the rockfill ratio of rockfill concrete by at least 5%, and up to 15%. This increased rockfill ratio reduces the amount of self-compacting concrete, further reducing cement usage and the overall hydration heat of rockfill concrete, thereby improving the environmental and economic performance of rockfill concrete.

[0045] In some embodiments, the coarse aggregate particle size of the high-performance self-compacting concrete 3 is 10 mm to 16 mm, the slump is 270 mm to 290 mm, the spread is 650 mm to 800 mm, the V-funnel passage time is 4 seconds to 15 seconds, and the self-compacting performance stability is greater than or equal to 1 hour (i.e., the time for the high-performance self-compacting concrete to maintain good fluidity is greater than or equal to 1). The maximum particle size of the coarse aggregate in the high-performance self-compacting concrete 3 is reduced from the conventional 20 cm to 16 cm, considering that an increase in the rockfill ratio of the rockfill concrete in this embodiment may result in a reduction in rockfill voids, to ensure that the high-performance self-compacting concrete 3 can flow smoothly in the voids of the two-graded rockfill body.

[0046] In some embodiments, the thickness h of the casting bin is generally set between 1.0m and 4.0m. Casting bin thickness is a critical parameter in the design and construction of hydraulic concrete dams. Existing casting bins for dam concrete or ungraded rockfill concrete have a thickness of 1m to 3m. However, in this embodiment, due to the lower heat of hydration of two-graded rockfill concrete, the casting bin can be thicker, up to 4m.

[0047] like Figures 2 to 5 As shown, the second aspect of the present disclosure is directed to Figure 1 The construction method of the two-graded rockfill concrete comprises the following steps:

[0048] (1) Prepare medium stone aggregate 1 and large stone aggregate 2, and prepare high-performance self-compacting concrete 3. Assume that the total mass of medium stone aggregate 1 entering the warehouse is M 中 , should meet the following requirements:

[0049] M 中 =α·r·ρ·V

[0050] Wherein, ρ is the density of the medium stone aggregate 1, which is set to 2700 kg / m 3 ; V is the volume of the casting bin. In this embodiment, the casting bin is 10m long, 5m wide and 2m thick, so the volume V of the casting bin is 100m 3 α is the proportion of medium-sized aggregate 1, i.e., the ratio of the total volume of medium-sized aggregate 1 to the total volume of the two-graded rockfill body. In this embodiment, α is set to 50%. r is the rockfill ratio, i.e., the ratio of the total volume of the two-graded rockfill body to the total volume of the two-graded rockfill concrete. When α = 50%, based on the aforementioned law that the rockfill ratio r varies with the proportion of medium-sized aggregate α, the rockfill ratio of the two-graded rockfill concrete can reach 66% to 70%. Substituting the above specific numerical values ​​into calculations, it can be obtained that the total mass of the medium-sized aggregate 1 entering the warehouse is 89.1t to 94.5t, with 90t being used in this embodiment. Large-sized aggregate 2 with a mass of no less than 90t must also be prepared.

[0051] (2) The formwork of the casting bin or its substitute 4 is supported, and then the large stone aggregate 2 and the medium stone aggregate 1 are simultaneously fed into the casting bin so that the two-graded rock mass in the casting bin reaches the set height, completing the entry of the two-graded rock mass into the bin, wherein the medium stone aggregate 1 and the large stone aggregate 2 are fed into the casting bin by either horizontal entry or vertical entry, or both. In this embodiment, the medium stone aggregate 1 is fed into the bin horizontally, specifically by a belt conveyor or its substitute 6 to transport the medium stone aggregate 1 horizontally to the top of the casting bin, and then the medium stone aggregate 1 is put into the casting bin; the large stone aggregate 2 is fed into the bin vertically, specifically by a tower crane or its substitute 5 to transport the large stone aggregate 2 vertically to the top of the casting bin, and then the large stone aggregate 2 is put into the casting bin, and the medium stone aggregate 1 and the large stone aggregate 2 are fed into the bin simultaneously.

[0052] (3) Pour high-performance self-compacting concrete 3 to make it flow and fill the voids in the two-graded rockfill until it reaches the designed height of the top of the silo, and finally form Figure 1 Two-graded rockfill concrete shown.

[0053] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0054] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and intent of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A two-graded rockfill concrete, characterized in that: The invention comprises a two-graded rockfill body arranged in a casting bin and high-performance self-compacting concrete filling the voids in the two-graded rockfill body, wherein the two-graded rockfill body is composed of medium-sized stone aggregates with a particle size of 150 mm to 350 mm and large-sized stone aggregates with a particle size greater than 350 mm; The ratio of the total volume of the medium block aggregate to the total volume of the two-graded rockfill body is defined as the medium block proportion α, and the ratio of the total volume of the two-graded rockfill body to the total volume of the two-graded rockfill concrete is defined as the rockfill ratio r, wherein the rockfill ratio r is a function of the medium block proportion α and the thickness of the casting bin; In engineering applications, the value range of the proportion of medium-sized rocks α is 30% to 70%, and the rockfill ratio r is 65% to 70%.

2. The two-graded rockfill concrete according to claim 1, characterized in that: The medium block stone aggregate and the large block stone aggregate are simultaneously fed into the casting bin, and the medium block stone aggregate and the large block stone aggregate are fed into the casting bin in a manner of either horizontal feeding or vertical feeding or both.

3. The two-graded rockfill concrete according to claim 1, characterized in that: The rockfill rate r shows a parabolic variation law of first increasing and then decreasing as the proportion of medium rocks α increases, specifically: When the proportion of the medium-sized rocks is α=0% to 30%, the rock-filling ratio r is 55% to 65%, and the rock-filling ratio r is positively correlated with the thickness of the casting bin; When the proportion of the medium-sized rocks α=30% to 70%, the rock-filling ratio r is 65% to 70%, and the positive correlation between the rock-filling ratio r and the thickness of the casting bin decreases with the increase of the proportion of the medium-sized rocks; When the proportion of the medium-sized rocks is α=40% to 60%, the rockfill ratio r reaches the maximum rockfill ratio of the two-graded rockfill concrete, i.e., 67% to 70%; When the proportion of the medium-sized rocks α=70% to 100%, the rock-filling ratio r is 62% to 65%, and the rock-filling ratio r is weakly correlated with the thickness of the casting bin.

4. The two-graded rockfill concrete according to claim 1, characterized in that: The high-performance self-compacting concrete has a coarse aggregate particle size of 10 mm to 16 mm, a slump of 270 mm to 290 mm, an expansion of 650 mm to 800 mm, a V-funnel passage time of 4 s to 15 s, and a self-compacting performance stability of greater than or equal to 1 hour.

5. The two-graded rockfill concrete according to claim 1, characterized in that: The thickness of the casting bin is 1.0m to 4.0m.

6. A construction method for the two-graded rockfill concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Prepare the medium block aggregate and the large block aggregate, and formulate the high performance self-compacting concrete. Assume that the total mass of the medium block aggregate entering the warehouse is M 中 , should meet the following requirements: M 中 =α·r·ρ·V Wherein, ρ is the density of the medium stone aggregate, V is the volume of the casting bin, α is the proportion of medium stone, that is, the ratio of the total volume of the medium stone aggregate to the total volume of the two-graded rockfill body, and r is the rockfill ratio, that is, the ratio of the total volume of the two-graded rockfill body to the total volume of the two-graded rockfill concrete; (2) supporting the formwork of the casting bin or its substitute, and then simultaneously feeding the large stone aggregate and the medium stone aggregate into the casting bin so that the two-graded rock pile in the casting bin reaches a set height, wherein the medium stone aggregate and the large stone aggregate are fed into the casting bin by either horizontal feeding or vertical feeding, or both; (3) pouring the high-performance self-compacting concrete so that it flows and fills the voids in the two-graded rockfill body until it reaches the designed height of the top of the silo surface, thereby forming the two-graded rockfill concrete.

7. The construction method according to claim 6, characterized in that: The tool used in the vertical warehousing method is a tower crane or a substitute thereof.

8. The construction method according to claim 6, characterized in that: The tool used in the horizontal warehousing method is a belt conveyor or a substitute thereof.

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