High-flow-state regenerated light aggregate concrete and method for backfilling high, narrow, long and narrow fertilizer grooves by using high-flow-state regenerated light aggregate concrete

Abstract

The invention discloses high-flow-state recycled light aggregate concrete, which is prepared from the following ingredients in parts by mass: 46 to 52 parts of curing agents, 415 to 432 parts of sand, 390 to 410 parts of recycled fine aggregates, 500 to 525 parts of slurry sheet powder, 15 to 19 parts of additives and 375 to 395 parts of water. In addition, the invention further provides a method for backfilling the high-narrow long-narrow fertilizer groove by using the high-flow-state regenerated light aggregate concrete, the high-narrow long-narrow fertilizer groove is blocked by adopting a segmented template, the high-flow-state regenerated light aggregate concrete is poured by using a pump truck, and the backfilling of the high-narrow long-narrow fertilizer groove is completed without vibrating. The high-flow-state regenerated light aggregate concrete is high in flowability and good in self-compaction performance and shows extremely high flowability, a mixture can flow by means of the gravity of the mixture and fill all corners in a fertilizer groove without vibration, and the problem that backfilling of the fertilizer groove cannot be completed in a foundation pit area of a high, narrow, long and narrow fertilizer groove part is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-fluidity recycled lightweight aggregate concrete, and particularly relates to a high-fluidity recycled lightweight aggregate concrete and a method for using the same for backfilling high-narrow and long fat grooves. Background Art

[0002] During the construction process of a building, the underground structure construction process usually involves carrying out underground structure operations after excavating the foundation pit fat groove, and then backfilling the fat groove after the construction of the underground exterior wall is completed. However, due to unique designs of some buildings, there are "high-narrow and long" fat grooves with a depth greater than 12 m and a width greater than 1.2 m. Such special fat grooves result in extremely limited backfilling sites, making it difficult for construction workers to reach the pouring surface for construction. The existing conventional fat groove backfilling methods are not applicable, resulting in difficulty in completing the backfilling of the fat grooves in some foundation pit areas.

[0003] In addition, traditionally, the backfilling of fat grooves mostly uses the 2:8 lime-soil process (i.e., lime-soil with a mass ratio of lime to soil of 2:8). However, this process has many drawbacks. It requires multi-layer backfilling and is extremely vulnerable to weather changes and relevant policies. In the scenario of "high-narrow and long" fat grooves, the operating space for construction machinery is severely insufficient, and it is difficult to guarantee the ramming quality. According to the calculation of the project duration quota, for every 100 m 3 backfilled manually, it takes 70 man-days, and the efficiency is extremely low. In addition, for the high-narrow and long fat grooves of deep foundation pits, there are great safety risks in the vertical transportation of lime-soil. Moreover, the process is complex, the single-layer backfilling thickness is limited, and multiple backfilling layers are required, resulting in high labor costs. Based on this, there is an urgent need to seek a new backfilling material and process to solve problems such as the influence of weather and policies, limited operating space for construction machinery, and easy settlement during ramming, improve the backfilling construction efficiency, and ensure that the safety, quality, and progress requirements are met.

[0004] Therefore, there is a need for a high-fluidity recycled lightweight aggregate concrete and a method for using the same for backfilling high-narrow and long fat grooves to overcome problems such as the influence of weather and policies, limited construction space, and difficulty in vibration ramming, improve the backfilling construction efficiency of fat grooves, and ensure that the safety, quality, and construction period requirements are met. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-fluidity recycled lightweight aggregate concrete in view of the deficiencies of the above-mentioned prior art. This high-fluidity recycled lightweight aggregate concrete is composed of a curing agent, sand, recycled fine aggregate, slurry powder, admixture, and water. It has high fluidity and good self-compacting performance. The slump expansion value can reach more than 680 mm, showing extremely high fluidity. The mixture can flow and fill every corner in the fat groove by its own gravity without vibration, solving the situation where the backfilling of some foundation pit areas in high-narrow and long fat grooves cannot be completed.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a high-fluidity recycled lightweight aggregate concrete, characterized in that the high-fluidity recycled lightweight aggregate concrete is composed of the following components in parts by mass: 46 to 52 parts of a curing agent, 415 to 432 parts of sand, 390 to 410 parts of recycled fine aggregate, 500 to 525 parts of slurry powder, 15 to 19 parts of an admixture, and 375 to 395 parts of water.

[0007] In the high-fluidity recycled lightweight aggregate concrete of the present invention, the curing agent inhibits the movement of sand and recycled fine aggregate to improve stability, reacts with substances on the surfaces of sand and recycled fine aggregate to improve adhesion and reduce the influence of water absorption, synergistically accelerates the gelling reaction with slurry powder, and works synergistically with the admixture to improve the workability of the high-fluidity recycled lightweight aggregate concrete, and on this basis, improves the strength and stability of the high-fluidity recycled lightweight aggregate concrete; the sand provides a skeleton for the slurry powder, changes the interface properties in combination with the admixture, and improves adhesion and stability in combination with water; the recycled fine aggregate provides an adsorption and reaction site for the slurry powder, and improves the workability of the high-fluidity recycled lightweight aggregate concrete in combination with the admixture; the slurry powder and the admixture affect each other's reaction rate and performance, ensuring the performance of the high-fluidity recycled lightweight aggregate concrete; the admixture adjusts the performance of the high-fluidity recycled lightweight aggregate concrete; water is used to optimize the water-binder ratio, so that sufficient paste fills the gaps between aggregates, forming a self-leveling ability, and cooperating to achieve the characteristics of high fluidity.

[0008] The above-mentioned high-fluidity recycled lightweight aggregate concrete is characterized in that the high-fluidity recycled lightweight aggregate concrete is composed of the following components in parts by mass: 48 to 51 parts of a curing agent, 418 to 427 parts of sand, 395 to 405 parts of recycled fine aggregate, 505 to 515 parts of slurry powder, 16 to 18 parts of an admixture, and 378 to 385 parts of water.

[0009] The above-mentioned high-fluidity recycled lightweight aggregate concrete is characterized in that the high-fluidity recycled lightweight aggregate concrete is composed of the following components in parts by mass: 50 parts of a curing agent, 423 parts of sand, 400 parts of recycled fine aggregate, 510 parts of slurry powder, 17 parts of an admixture, and 380 parts of water.

[0010] The above-mentioned high-fluidity recycled lightweight aggregate concrete is characterized in that the solidifying agent meets the "Technical Standard for Filling with Premixed Fluid-solidified Soil", the sand has a particle size of 5 mm to 16 mm and a continuous gradation, the fineness modulus of the recycled fine aggregate is 2.5 to 3.0, the passing rate through the 0.315 mm sieve hole is not less than 15%, and the passing rate through the 0.15 mm sieve hole is not less than 5%. The admixtures are water reducing agent and air entraining agent. In the present invention, the solidifying agent required in the "Technical Standard for Filling with Premixed Fluid-solidified Soil" is a composite cementitious material mainly composed of CaO, active Al2O3 and SiO2, and at the same time, functional additives and activity activators are added. The solidifying agent in the present invention is composed of the following components in parts by mass: active Al2O3 8% to 15%, SiO2 20% to 30%, Na5P3O 10 0.5% to 1.5%, NaCl 1.0% to 3.0% and the balance CaO, where Na5P3O 10 and NaCl are used as reaction activators to activate potential active components and accelerate the cementitious reaction process; in the present invention, sand with continuous gradation is adopted, and the parameters of the recycled fine aggregate are controlled to make the particle gradations of the sand and the recycled fine aggregate complementary, avoiding excessive void ratio of aggregate accumulation, ensuring the performance of the high-fluidity recycled lightweight aggregate concrete, increasing the content of fine particles in the concrete to form a lubricating layer and avoiding pipe blockage; in the present invention, the water reducing agent adopts a polycarboxylate-based high-performance water reducing agent with a water reducing rate of ≥25%, significantly reducing the amount of mixing water, while maintaining fluidity, controlling the slump by adjusting the dosage, adopting an air entraining agent to introduce tiny and uniform air bubbles, reducing the friction between aggregates, improving workability, and controlling the air bubble stability by adjusting the dosage to avoid strength loss;

[0011] The above-mentioned high-fluidity recycled lightweight aggregate concrete is characterized in that the paste powder is composed of the following components in parts by mass: fly ash 20% to 30%, mineral powder 10% to 20%, fine powder of construction waste 5% to 15%, and the balance is cement. In the present invention, by adopting fly ash and controlling its quality, the spherical particles of fly ash play the role of ball bearings, reducing the viscosity of the concrete and improving fluidity, replacing part of the cement to reduce the heat of hydration. By adding mineral powder and controlling its quality, the gaps between cement particles are filled, improving the density of the concrete. By adding fine powder of construction waste and controlling its quality, while reducing the cost, as an inert fine filler, it improves the continuity of gradation. By adding cement, it provides basic bonding strength, ensures the encapsulation of aggregates, and improves the strength of the concrete.

[0012] The above-mentioned high-fluidity recycled lightweight aggregate concrete is characterized in that the paste powder is prepared by the following steps:

[0013] Step 1: crushing, sorting and screening the construction waste in sequence to obtain fine powder of construction waste; the construction waste includes one or more of waste bricks, concrete, old mortar, broken ceramics, stone chips, powder and ash, and the particle size of the fine powder of construction waste is less than 9.5 mm;

[0014] Step 2: Mix the construction waste fine powder obtained in step 1 with cement, fly ash and mineral powder to obtain slurry powder.

[0015] The present invention reduces the exploitation of natural resources and the pollution to the environment by adopting construction waste, reduces the cost and meets the environmental protection requirements.

[0016] The above-mentioned high-flow recycled lightweight aggregate concrete is characterized in that the expansion of the high-flow recycled lightweight aggregate concrete is greater than 680 mm, and the strength after curing for 28 days after pouring is greater than 3.2 MPa. The expansion of the high-flow recycled lightweight aggregate concrete of the present invention is greater than 680mm, achieving the characteristics of high flowability. It can rely on its own gravity to fill every corner of the fertilizer trough without vibration, ensuring dense and uniform backfill, overcoming the quality problems caused by the difficulty of traditional backfilling and vibration. The strength of the high-flow recycled lightweight aggregate concrete after pouring and curing for 28 days is greater than 3.2MPa, which meets the use requirements; the high-flow recycled lightweight aggregate concrete involved in the present invention shows excellent performance advantages, and its expansion is far beyond the conventional standard after professional testing, and is stably greater than 680mm. This outstanding high-flowability characteristic makes it extremely valuable in practical applications. When carrying out fertilizer trough backfilling operations, there is no need to use vibration equipment. The concrete can rely on its own gravity to flow naturally and smoothly to every corner of the fertilizer trough like a smart water flow, including those narrow, hidden areas that are difficult to reach with conventional construction methods. This feature ensures the high efficiency of the backfilling process, greatly saves manpower and time costs, and effectively avoids It eliminates quality defects such as honeycombs and holes caused by inadequate vibration, ensures the density and uniformity of backfill, and completely overcomes many quality problems caused by difficult vibration in traditional backfilling methods; from the perspective of strength performance, after the pouring of high-flow recycled lightweight aggregate concrete, after a standard curing period of 28 days, its strength performance is also excellent, with a compressive strength greater than 3.2MPa, which fully meets the use requirements of fertilizer trough backfill. This strength can not only provide reliable support for the fertilizer trough, effectively withstand the load from the upper structure and the lateral pressure of the surrounding soil, but also maintain the stability of the structure during long-term use, and resist the erosion and influence of environmental factors. In addition, the concrete of the present invention also performs well in durability. Through special mix design and raw material screening, it has good impermeability, frost resistance and erosion resistance, and can adapt to the fertilizer trough backfill needs under different climatic conditions and complex engineering environments, greatly extending the service life of the project and reducing the later maintenance costs.

[0017] In addition, the present invention also provides a method for backfilling a high, narrow, long and narrow fat groove with high-fluidity recycled lightweight aggregate concrete, which is characterized in that the method comprises the following process: using segmented formwork to block in the high, narrow, long and narrow fat groove and using a pump truck to pour the high-fluidity recycled lightweight aggregate concrete without vibration to complete the backfilling of the high, narrow, long and narrow fat groove; the depth of the high, narrow, long and narrow fat groove is greater than 12 m, and the width is greater than 1.2 m.

[0018] The high-fluidity self-compacting concrete used for backfilling the high, narrow, long and narrow fat groove in the present invention has innovations and advantages in many aspects. In terms of performance, its self-compacting property is manifested as good fluidity, and it can fill every corner of the fat groove by relying on its own gravity without vibration, ensuring dense and uniform backfilling and overcoming the quality problems caused by difficult vibration in traditional backfilling; the strength and durability can be achieved by optimizing the mix ratio, having high strength and good durability while meeting the self-compacting property, and bearing various loads and environmental impacts of the fat groove to ensure the long-term stability of the structure; in terms of green environmental protection, using construction waste aggregates, engineering concrete waste slurry, etc. as the main raw materials, adding appropriate amounts of cementitious materials, admixtures and water, reducing the exploitation of natural resources and environmental pollution. The innovation of the construction process is reflected in that the pumping construction can transport the concrete to the fat groove by means of pumping technology, realizing long-distance and high-efficiency construction, being applicable to the high, narrow, long and narrow fat groove with limited construction space, reducing the difficulty of manual handling and pouring. The layered pouring adopts appropriate thickness for layering for the high, narrow, long and narrow fat groove, controls the pouring speed and height, avoids segregation and bleeding, and ensures the pouring quality, and the pouring is not affected by weather policies, etc.; the intelligent monitoring uses sensor technology and information means to monitor parameters such as the flow state, pouring speed, pressure, etc. during the concrete pouring process in real time, ensuring controllable construction and timely solving problems, and at the same time avoiding safety accidents of personnel working in confined spaces.

[0019] In terms of construction performance, high-fluidity self-compacting recycled concrete has high fluidity and self-compactness. Without the need for vibration, it can fill every corner of the high, narrow, long and wide backfill trench by relying on its own gravity, ensuring uniform compaction density of the backfill and effectively avoiding the internal void problems that may occur due to insufficient vibration in traditional 2:8 backfill. Its good fluidity can also improve the construction speed and reduce the construction time. In terms of mechanical properties, the strength development of high-fluidity self-compacting recycled concrete is good, and it can better meet the bearing requirements after the backfill of deep foundation pit backfill trenches. The test-mixed 28-day strength result is 3.2 MPa. In contrast, the strength development of traditional 2:8 backfill materials may be difficult to accurately control. When bearing loads such as lateral earth pressure, high-fluidity self-compacting recycled concrete can provide more stable and reliable support, enhancing the stability of the overall structure of the deep foundation pit. From an environmental protection perspective, high-fluidity self-compacting recycled concrete uses recycled aggregates, greatly reducing the exploitation of natural aggregates and reducing the pressure of stacking and treating construction waste, which meets the environmental protection requirements of modern engineering construction. Traditional 2:8 backfill mainly relies on natural materials, consuming a large amount of natural resources. In terms of durability, high-fluidity self-compacting recycled concrete has good durability indicators such as impermeability and frost resistance; in the complex underground environment of deep foundation pits, it can effectively resist damage effects such as groundwater erosion and freeze-thaw cycles, extending the service life of the backfill structure of the backfill trench. Traditional 2:8 backfill may be relatively weak in terms of durability, and problems such as structural deterioration may occur after long-term use; in terms of economic cost, although the material preparation cost of high-fluidity self-compacting recycled concrete in the early stage may be slightly higher than that of traditional 2:8 backfill, due to its good construction performance, it reduces the manual vibration cost, and because of its good durability, it can reduce the later maintenance cost, and overall it has a certain cost advantage.

[0020] The above method is characterized in that the process of segmental formwork plugging meets the following conditions: stratified stepped progressive pouring is adopted, and when pouring the high-fluidity recycled lightweight aggregate concrete for each layer, a step of 0.8 m to 1.2 m is offset from the next layer. The thickness of each layer is 250 mm to 350 mm. When pouring the high-fluidity recycled lightweight aggregate concrete for the lower layer, multiple steel bars are embedded at the step, and the spacing of the steel bars is 400 mm to 600 mm, the embedded length is 200 mm to 300 mm, and the exposed length is 80 mm to 100 mm. When pouring the high-fluidity recycled lightweight aggregate concrete for the upper layer, formwork is set at the position of the steel bars, and the formwork is supported by square timbers and steel pipes. By setting steel bars in the present invention, formwork plugging construction is carried out for the top support reinforcement of the upper layer formwork. The recycled concrete is fed in a large inclined plane in layers and poured in multiple times. The height of a single pouring shall not be greater than 2 m. Stratified stepped progressive pouring is adopted, with segmented fixed points, thin-layer pouring and sequential advancement to ensure the avoidance of construction cold joints. The thickness of each layer is 250 mm to 350 mm for layered pouring. Under the condition of no vibration, the concrete can maintain a good interface bond, without obvious segregation and bleeding phenomena. This thickness range is conducive to the self-bonding between material layers and can also ensure the overall pouring efficiency. By embedding multiple steel bars, it is convenient to install the formwork, thus facilitating the pouring of the high-fluidity recycled lightweight aggregate concrete for the upper layer.

[0021] The above method is characterized in that when pouring the high-fluidity recycled lightweight aggregate concrete, waterproof construction is carried out on the outer wall of the high, narrow, long and narrow fat groove, and the height of the waterproof construction is greater than the height of the poured high-fluidity recycled lightweight aggregate concrete. The free fall height of the high-fluidity recycled lightweight aggregate concrete during pouring does not exceed 2 m. In the present invention, through waterproof construction, it is ensured that water does not seep back from the gaps in the outer wall. By controlling the free fall height of the high-fluidity recycled lightweight aggregate concrete during pouring not to exceed 2 m, the effect of preventing the pollution and damage of the outer wall waterproof is achieved.

[0022] The present invention has the following advantages compared with the prior art:

[0023] 1. The high-fluidity recycled lightweight aggregate concrete is composed of a curing agent, sand, recycled fine aggregate, slurry powder, admixture and water in the present invention. It has high fluidity and good self-compacting property. The slump expansion value can reach more than 680 mm, showing extremely high fluidity. The mixture can flow by its own gravity and fill every corner in the fat groove without vibration, avoiding quality hazards such as honeycombing and holes caused by the inability to vibrate in narrow spaces, ensuring uniform and dense backfilling, and solving the problems that the high, narrow, long and narrow fat groove is deep in depth, narrow in width, limited in backfilling site, large in height, and it is very difficult for operators to construct on the pouring surface, resulting in the situation that partial foundation pit areas cannot complete the fat groove backfilling.

[0024] 2. The high-fluidity recycled lightweight aggregate concrete of the present invention combines the characteristics of fluid soil and recycled aggregate. It is easy to prepare, has low cost, appropriate strength, and good durability. Its compressive strength after 28 days of standard curing can reach above 3.2 MPa, fully meeting the bearing capacity requirements for backfilling the fat groove. The hardened backfill body forms a certain strength by itself, can reliably support the load of the upper structure and resist the lateral pressure of the surrounding soil, ensuring the long-term stability of the deep foundation pit structure. In addition, the optimized mix ratio endows the concrete with excellent durability, including good impermeability, freeze-thaw resistance, and erosion resistance, enabling it to adapt to the underground humid environment and cold climate, providing guarantee for the long-term use of the fat groove backfill structure.

[0025] 3. The high-fluidity recycled lightweight aggregate concrete of the present invention has self-leveling and pumpable properties. During construction, it can be directly transported and poured over a long distance by a pump truck, greatly improving the construction efficiency. Compared with the traditional manual layered ramming and filling, for every 100 m 3 of concrete backfill, it only takes about 4 hours to complete, significantly reducing the labor input, shortening the construction period, and being less affected by weather. It can also be carried out smoothly during the rainy season or winter. At the same time, since there is no need for personnel to go down into the deep trench for vibration, the safety risks of limited space operation and high-altitude vertical transportation are reduced, ensuring construction safety.

[0026] 4. The present invention uses solid wastes such as recycled fine aggregate and construction waste fine powder as the main raw materials, supplemented by a small amount of cement, fly ash and other cementitious materials, which not only reduces the exploitation and utilization of natural sand and gravel, reduces the pressure of construction waste disposal, and meets the requirements of green construction and sustainable development; at the same time, the raw material cost is relatively low. Considering factors such as labor saving and construction period shortening, the backfill scheme of the present invention can save about 30% of the total project cost compared with the traditional lime soil backfill, and significantly reduce pollution such as dust, noise, and mud discharge during the construction process.

[0027] 5. The high-fluidity recycled lightweight aggregate concrete provided by the present invention and its method for backfilling high-narrow and long fat grooves have obvious advantages in construction performance, mechanical properties, durability and environmental protection, can effectively solve the backfill problem of high-narrow and long foundation pit fat grooves, and have broad engineering application prospects.

[0028] The technical solutions of the present invention will be further described in detail below through the drawings and embodiments. Brief Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of segmented formwork plugging in the present invention.

[0030] Description of the reference numerals:

[0031] 1 - High-fluidity recycled lightweight aggregate concrete in the lower layer; 2 - Steel bars;

[0032] 3 - Formwork; 4 - Square timber; 5 - Steel pipe;

[0033] 6 - High-fluidity recycled lightweight aggregate concrete for the upper layer. Specific implementation manner

[0034] Figure 1 It is a structural schematic diagram of segmented formwork plugging in the present invention. As can be seen from Figure 1 , multiple steel bars 2 are embedded in the high-fluidity recycled lightweight aggregate concrete 1 of the lower layer. According to the multiple steel bars 2, a formwork 3 is provided, and the formwork 3 is supported by square timbers 4 and steel pipes 5, so as to facilitate the pouring of the high-fluidity recycled lightweight aggregate concrete 6 of the upper layer.

[0035] Example 1

[0036] The high-fluidity recycled lightweight aggregate concrete of this example includes: 50 parts of curing agent, 423 parts of sand, 400 parts of recycled fine aggregate, 510 parts of slurry powder, 17 parts of admixture, and 380 parts of water.

[0037] The slurry powder of this example is prepared by the following steps:

[0038] Step 1: The construction waste is successively crushed, sorted, and screened to obtain construction waste fine powder; the construction waste includes waste bricks, concrete, old mortar, broken ceramics, stone chips, powder, and lime soil, and the particle size of the construction waste fine powder is less than 9.5 mm;

[0039] Step 2: The construction waste fine powder obtained in Step 1 is mixed with cement, fly ash, and slag powder to obtain slurry powder; the mass content of fly ash in the slurry powder is 25%, the mass content of slag powder is 15%, the mass content of construction waste fine powder is 8%, and the balance is cement.

[0040] The method for using the high-fluidity recycled lightweight aggregate concrete of this embodiment for backfilling high-narrow and long narrow trenches includes the following process: In the high-narrow and long narrow trenches, segmented formwork is used for blocking and a pump truck is used to pour the high-fluidity recycled lightweight aggregate concrete without vibration to complete the backfilling of the high-narrow and long narrow trenches; the process of segmented formwork blocking meets the following conditions: Stratified stepped gradual retreat pouring is adopted, and when pouring each layer of high-fluidity recycled lightweight aggregate concrete, a step of 0.8 m to 1.2 m is offset from the next layer, and the thickness of each layer is 250 mm to 350 mm. When pouring the lower layer of high-fluidity recycled lightweight aggregate concrete, multiple steel bars are buried at the step, and the spacing of the steel bars is 400 mm to 600 mm, the buried length is 200 mm to 300 mm, and the exposed length is 80 mm to 100 mm. When pouring the upper layer of high-fluidity recycled lightweight aggregate concrete, formwork is set at the position of the steel bars, and the formwork is supported by square timbers and steel pipes; when pouring the high-fluidity recycled lightweight aggregate concrete, waterproof construction is carried out on the outer wall of the high-narrow and long narrow trenches, and the height of the waterproof construction is greater than the height of the poured high-fluidity recycled lightweight aggregate concrete. The free fall height of the high-fluidity recycled lightweight aggregate concrete during pouring does not exceed 2 m; the depth of the high-narrow and long narrow trenches is greater than 12 m, and the width is greater than 1.2 m.

[0041] In this embodiment, for every 100 m 3 The construction period required for the high-fluidity recycled lightweight aggregate concrete is about 4 h. Using a pump truck for pouring, there is no risk of deep foundation pit material transportation. After the high-fluidity recycled lightweight aggregate concrete solidifies, it has self-holding force and can reduce the lateral pressure on the structure, and the structure does not need to be strengthened. The strength of the recycled lightweight aggregate after solidification is about 3.5 MPa, and it has a certain self-bearing capacity, thus reducing the lateral pressure of the backfill soil on the underground outer wall. There is no need for additional reinforcement of the underground structure. During the entire backfilling process, the discharge of dust and mud is significantly reduced, and the pressure of pollution control and haze reduction is small, meeting the requirements of green construction. The backfilling of the trench is constructed from west to east along with the main structure. Slump detection is carried out during pouring, and there is no segregation or bleeding. The free flow distance after pouring is about 50 m, and the pouring effect is good. Through cost calculation, the cost is saved by about 30%, reflecting significant economic and social benefits.

[0042] Comparative Example 1

[0043] In this comparative example, 2:8 lime soil is used for backfilling.

[0044] In this comparative example, the use of 2:8 lime soil for backfilling is greatly affected by weather and policies, the operation space for construction machinery and tools is limited, and it is difficult to ensure the ramming quality. For every 100 m backfilled manually 3It takes 70 man-days. The foundation pit is relatively deep, and there are safety risks during the vertical transportation of lime soil. There is a certain lateral pressure on the backfill soil, and the garage structure needs to be strengthened to resist lateral horizontal forces. The quality of manual backfill is not easy to guarantee. The strength of the backfill soil is about 0.2 MPa. The pressure of pollution control and haze reduction is high. It is a conventional process without green construction content. The process is complex, the single backfill thickness is limited, and there are many backfill layers, which requires a large amount of labor costs. Lime soil is significantly affected by the weather and cannot be operated in rainy days and is prone to mud loss. The traditional 2:8 lime soil process exposes deficiencies such as cumbersome processes, low efficiency, many safety hazards, and difficult quality guarantee in the backfill of high, narrow, long and fat trenches.

[0045] Example 2

[0046] The high-fluidity recycled lightweight aggregate concrete of this example includes: 51 parts of curing agent, 427 parts of sand, 395 parts of recycled fine aggregate, 505 parts of slurry powder, 16 parts of admixture, and 385 parts of water.

[0047] The slurry powder of this example is prepared by the following steps:

[0048] Step 1: Crush, separate and screen the construction waste in turn to obtain construction waste fine powder; the construction waste includes waste bricks, and the particle size of the construction waste fine powder is less than 9.5 mm;

[0049] Step 2: Mix the construction waste fine powder obtained in Step 1 with cement, fly ash, and slag powder to obtain slurry powder; the mass content of fly ash in the slurry powder is 23%, the mass content of slag powder is 14%, the mass content of construction waste fine powder is 9%, and the balance is cement.

[0050] The method for using the high-fluidity recycled lightweight aggregate concrete of this embodiment for backfilling high-narrow and long and narrow foundation pits includes the following process: In the high-narrow and long and narrow foundation pit, segmented formwork is used for plugging, and a pump truck is used to pour the high-fluidity recycled lightweight aggregate concrete without vibration to complete the backfilling of the high-narrow and long and narrow foundation pit; the process of segmented formwork plugging meets the following conditions: stratified stepped progressive pouring is adopted, when pouring each layer of high-fluidity recycled lightweight aggregate concrete, a step of 0.8 m to 1.2 m is offset from the next layer, the thickness of each layer is 250 mm to 350 mm, when pouring the lower layer of high-fluidity recycled lightweight aggregate concrete, multiple steel bars are buried at the step, and the spacing of the steel bars is 400 mm to 600 mm, the buried length is 200 mm to 300 mm, and the exposed length is 80 mm to 100 mm. When pouring the upper layer of high-fluidity recycled lightweight aggregate concrete, formwork is set at the position of the steel bars, and the formwork is supported by square timbers and steel pipes; when pouring the high-fluidity recycled lightweight aggregate concrete, waterproof construction is carried out on the outer wall of the high-narrow and long and narrow foundation pit, and the height of the waterproof construction is greater than the height of the poured high-fluidity recycled lightweight aggregate concrete. The free fall height of the high-fluidity recycled lightweight aggregate concrete during pouring does not exceed 2 m; the depth of the high-narrow and long and narrow foundation pit is greater than 12 m, and the width is greater than 1.2 m.

[0051] In this embodiment, for every 100 m 3 The construction period required for the high-fluidity recycled lightweight aggregate concrete is about 4 h. It is poured by a pump truck, and there is no risk of deep foundation pit material transportation. After the high-fluidity recycled lightweight aggregate concrete solidifies, it has self-holding force and can reduce the lateral pressure on the structure, and the structure does not need to be strengthened. The strength of the recycled lightweight aggregate after solidification is about 3.4 MPa, and it has a certain self-bearing capacity, thereby reducing the lateral pressure of the backfill soil on the underground outer wall, and there is no need for additional reinforcement of the underground structure. The dust and mud discharge during the entire backfilling process are significantly reduced, and the pressure of pollution control and haze reduction is small, meeting the requirements of green construction. The backfilling of the foundation pit is constructed from west to east along with the main structure. Slump detection is carried out during pouring, and there is no segregation or bleeding. The free flow distance after pouring is about 50 m, and the pouring effect is good. Through cost calculation, the cost is saved by about 30%, reflecting significant economic and social benefits.

[0052] Example 3

[0053] The high-fluidity recycled lightweight aggregate concrete of this embodiment includes: 48 parts of curing agent, 418 parts of sand, 405 parts of recycled fine aggregate, 515 parts of slurry powder, 18 parts of admixture, and 378 parts of water.

[0054] The slurry powder of this embodiment is prepared through the following steps:

[0055] Step 1: The construction waste is successively crushed, sorted, and screened to obtain construction waste fine powder; the construction waste includes waste bricks, concrete, and old mortar, and the particle size of the construction waste fine powder is less than 9.5 mm;

[0056] Step 2: Mix the fine construction waste powder obtained in Step 1 with cement, fly ash, and mineral powder to obtain the slurry powder; the mass content of fly ash in the slurry powder is 26%, the mass content of mineral powder is 17%, the mass content of the fine construction waste powder is 10%, and the balance is cement.

[0057] The method for using the high-fluidity recycled lightweight aggregate concrete of this embodiment for backfilling high-narrow and long narrow trenches includes the following process: In the high-narrow and long narrow trenches, use segmented formwork to block and use a pump truck to pour the high-fluidity recycled lightweight aggregate concrete without vibration to complete the backfilling of the high-narrow and long narrow trenches; the process of segmented formwork blocking meets the following conditions: Adopt layered stepped progressive pouring. When pouring each layer of high-fluidity recycled lightweight aggregate concrete, stagger 0.8 m to 1.2 m steps with the next layer. The thickness of each layer is 250 mm to 350 mm. When pouring the lower layer of high-fluidity recycled lightweight aggregate concrete, bury multiple steel bars at the steps, and the spacing of the steel bars is 400 mm to 600 mm, the buried length is 200 mm to 300 mm, and the exposed length is 80 mm to 100 mm. When pouring the upper layer of high-fluidity recycled lightweight aggregate concrete, set formwork at the positions of the steel bars and support the formwork with square timbers and steel pipes; when pouring the high-fluidity recycled lightweight aggregate concrete, perform waterproof construction on the outer wall of the high-narrow and long narrow trenches, and the height of the waterproof construction is greater than the height of the poured high-fluidity recycled lightweight aggregate concrete. The free fall height of the high-fluidity recycled lightweight aggregate concrete during pouring does not exceed 2 m; the depth of the high-narrow and long narrow trenches is greater than 12 m, and the width is greater than 1.2 m.

[0058] In this embodiment, for every 100 m 3 The construction period required for the high-fluidity recycled lightweight aggregate concrete is about 4 h. Using a pump truck for pouring, there is no risk of material transportation in deep foundation pits. After the high-fluidity recycled lightweight aggregate concrete solidifies, it has self-supporting force, which can reduce the lateral pressure on the structure. The structure does not need to be strengthened. The strength of the recycled lightweight aggregate after solidification is about 3.3 MPa, with a certain self-bearing capacity, thus reducing the lateral pressure of the backfill soil on the underground outer wall. There is no need to additionally reinforce the underground structure. The dust and mud discharge during the entire backfilling process are significantly reduced, and the pressure of pollution control and haze reduction is small, meeting the requirements of green construction. The backfilling of the narrow trench is constructed from west to east along with the main structure. Slump detection is carried out during pouring, and there is no segregation or bleeding. The free flow distance after pouring is about 50 m, and the pouring effect is good. Through cost calculation, the cost is saved by about 30%, reflecting significant economic and social benefits.

[0059] Example 4

[0060] The high-fluidity recycled lightweight aggregate concrete of this embodiment includes: 46 parts of curing agent, 415 parts of sand, 410 parts of recycled fine aggregate, 500 parts of slurry powder, 19 parts of admixture, and 375 parts of water.

[0061] The slurry powder of this embodiment is prepared through the following steps:

[0062] Step 1: The construction waste is successively crushed, sorted, and screened to obtain fine construction waste powder; the construction waste includes one or more of waste bricks, concrete, old mortar, broken ceramics, stone chips, powder, and lime soil, and the particle size of the fine construction waste powder is less than 9.5 mm;

[0063] Step 2: The fine construction waste powder obtained in Step 1 is mixed with cement, fly ash, and slag powder to obtain slurry powder; the mass content of fly ash in the slurry powder is 20%, the mass content of slag powder is 20%, the mass content of fine construction waste powder is 15%, and the balance is cement.

[0064] The method for using the high-fluidity recycled lightweight aggregate concrete of this embodiment for backfilling high-narrow and long and narrow fat grooves includes the following process: In the high-narrow and long and narrow fat groove, segmented formwork is used for plugging and a pump truck is used to pour the high-fluidity recycled lightweight aggregate concrete without vibration to complete the backfilling of the high-narrow and long and narrow fat groove; the process of segmented formwork plugging meets the following conditions: stratified stepped progressive pouring is adopted, and when pouring each layer of high-fluidity recycled lightweight aggregate concrete, a step of 0.8 m to 1.2 m is offset from the next layer, the thickness of each layer is 250 mm to 350 mm, when pouring the lower layer of high-fluidity recycled lightweight aggregate concrete, multiple steel bars are buried at the step, and the spacing of the steel bars is 400 mm to 600 mm, the buried length is 200 mm to 300 mm, and the exposed length is 80 mm to 100 mm. When pouring the upper layer of high-fluidity recycled lightweight aggregate concrete, formwork is set at the position of the steel bars, and the formwork is supported by square timbers and steel pipes; when pouring the high-fluidity recycled lightweight aggregate concrete, waterproof construction is carried out on the outer wall of the high-narrow and long and narrow fat groove, and the height of the waterproof construction is greater than the height of the poured high-fluidity recycled lightweight aggregate concrete. The free fall height of the high-fluidity recycled lightweight aggregate concrete during pouring does not exceed 2 m; the depth of the high-narrow and long and narrow fat groove is greater than 12 m, and the width is greater than 1.2 m.

[0065] In this embodiment, for every 100 m 3 The construction period required for pouring the high-fluidity recycled lightweight aggregate concrete is about 4 h. Using a pump truck for pouring, there is no risk of material transportation in deep foundation pits. After the high-fluidity recycled lightweight aggregate concrete solidifies, it has self-holding force and can reduce the lateral pressure on the structure. The structure does not need to be strengthened. The strength of the recycled lightweight aggregate after solidification is about 3.3 MPa, and it has a certain self-bearing capacity, thereby reducing the lateral pressure of the backfill soil on the underground outer wall. There is no need to additionally reinforce the underground structure. During the entire backfilling process, the discharge of dust and slurry is significantly reduced, and the pressure of pollution control and haze reduction is small, meeting the requirements of green construction. The backfilling of the fat groove is constructed from west to east along with the main structure. Slump detection is carried out during pouring, and there is no segregation or bleeding. The free flow distance after pouring is about 50 m, and the pouring effect is good. After cost calculation, the cost is saved by about 30%, reflecting significant economic and social benefits.

[0066] Example 5

[0067] The high-fluidity recycled lightweight aggregate concrete of this example includes: 52 parts of curing agent, 432 parts of sand, 390 parts of recycled fine aggregate, 525 parts of slurry powder, 15 parts of admixture, and 395 parts of water.

[0068] The slurry powder of this example is prepared through the following steps:

[0069] Step 1: Crush, sort, and screen construction waste in sequence to obtain fine powder of construction waste; the construction waste includes old mortar, broken ceramics, stone chips, powder, and lime soil, and the particle size of the fine powder of construction waste is less than 9.5 mm;

[0070] Step 2: Mix the fine powder of construction waste obtained in Step 1 with cement, fly ash, and slag powder to obtain slurry powder; the mass content of fly ash in the slurry powder is 30%, the mass content of slag powder is 10%, the mass content of the fine powder of construction waste is 5%, and the balance is cement.

[0071] The method for using the high-fluidity recycled lightweight aggregate concrete of this example for backfilling high-narrow and long and narrow foundation trenches includes the following process: Use segmented formwork to block and use a pump truck to pour the high-fluidity recycled lightweight aggregate concrete in the high-narrow and long and narrow foundation trenches without vibration to complete the backfilling of the high-narrow and long and narrow foundation trenches; the process of segmented formwork blocking meets the following conditions: Adopt layered stepped gradual withdrawal pouring, with a step of 0.8 m to 1.2 m between each layer of high-fluidity recycled lightweight aggregate concrete pouring and the next layer, and the thickness of each layer is 250 mm to 350 mm. When pouring the high-fluidity recycled lightweight aggregate concrete in the lower layer, bury multiple steel bars at the step, and the spacing of the steel bars is 400 mm to 600 mm, the buried length is 200 mm to 300 mm, and the exposed length is 80 mm to 100 mm. When pouring the high-fluidity recycled lightweight aggregate concrete in the upper layer, set up formwork at the position of the steel bars and support the formwork with square timbers and steel pipes; when pouring the high-fluidity recycled lightweight aggregate concrete, carry out waterproof construction on the outer wall of the high-narrow and long and narrow foundation trench, and the height of the waterproof construction is greater than the height of the poured high-fluidity recycled lightweight aggregate concrete, and the free fall height of the high-fluidity recycled lightweight aggregate concrete during pouring does not exceed 2 m; the depth of the high-narrow and long and narrow foundation trench is greater than 12 m, and the width is greater than 1.2 m.

[0072] In this example, for every 100 m of pouring 3The construction period required for high-fluidity recycled lightweight aggregate concrete is about 4 hours. It is poured using a concrete pump truck, eliminating the risk of material transportation in deep foundation pits. After the high-fluidity recycled lightweight aggregate concrete solidifies, it has self-holding force, which can reduce the lateral pressure on the structure, and the structure does not need to be strengthened. The strength of the recycled lightweight aggregate after solidification is about 3.4 MPa, with a certain self-bearing capacity, thus reducing the lateral pressure of the backfill soil on the underground exterior wall and eliminating the need for additional reinforcement of the underground structure. The dust and mud emissions during the entire backfill process are significantly reduced, resulting in less pollution control and haze reduction pressure, meeting the requirements of green construction. The backfill of the side ditch is constructed from west to east along with the main structure. The slump is detected during pouring, and there is no segregation or bleeding. The free-flowing distance after pouring is about 50 m, and the pouring effect is good. The cost is estimated to be saved by about 30%, reflecting significant economic and social benefits.

[0073] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A high-fluidity recycled lightweight aggregate concrete, characterized in that, The high-fluidity recycled lightweight aggregate concrete is composed of the following components by mass parts: 46 parts to 52 parts of curing agent, 415 parts to 432 parts of sand, 390 parts to 410 parts of recycled fine aggregate, 500 parts to 525 parts of slurry powder, 15 parts to 19 parts of admixture, and 375 parts to 395 parts of water.

2. The high-fluidity recycled lightweight aggregate concrete according to claim 1, wherein, The high-fluidity recycled lightweight aggregate concrete is composed of the following components by mass parts: 48 parts to 51 parts of curing agent, 418 parts to 427 parts of sand, 395 parts to 405 parts of recycled fine aggregate, 505 parts to 515 parts of slurry powder, 16 parts to 18 parts of admixture, and 378 parts to 385 parts of water.

3. A highly fluid regenerated lightweight aggregate concrete according to claim 1, characterized in that The high-fluidity recycled lightweight aggregate concrete is composed of the following components by mass parts: 50 parts of curing agent, 423 parts of sand, 400 parts of recycled fine aggregate, 510 parts of slurry powder, 17 parts of admixture, and 380 parts of water.

4. A high-fluidity recycled lightweight aggregate concrete according to claim 1, characterized in that, The curing agent meets the "Technical Standard for Filling with Premixed Fluidized Solidified Soil". The particle size of the sand is 5mm to 16mm and has a continuous gradation. The fineness modulus of the recycled fine aggregate is 2.5 to 3.0, the passing rate through the 0.315mm sieve hole is not less than 15%, and the passing rate through the 0.15mm sieve hole is not less than 5%. The admixture is a water reducing agent and an air entraining agent.

5. The high-fluidity recycled lightweight aggregate concrete according to claim 1, wherein The slurry powder is composed of the following components by mass parts: 20% to 30% of fly ash, 10% to 20% of mineral powder, 5% to 15% of fine powder of construction waste, and the balance is cement.

6. The high-fluidity recycled lightweight aggregate concrete according to claim 5, characterized in that The slurry powder is prepared through the following steps: Step 1: Crush, separate, and screen the construction waste in sequence to obtain fine powder of construction waste. The construction waste includes one or more of waste bricks, concrete, old mortar, broken ceramics, stone chips, powder, and lime soil. The particle size of the fine powder of construction waste is less than 9.5mm. Step 2: Mix the fine powder of construction waste obtained in Step 1 with cement, fly ash, and mineral powder to obtain the slurry powder.

7. A high-fluidity recycled lightweight aggregate concrete according to claim 1, characterized in that, The slump flow of the high-fluidity recycled lightweight aggregate concrete is greater than 680mm, and the strength after curing for 28 days is greater than 3.2MPa.

8. A method for backfilling a high, narrow, long and narrow fat groove with high-fluidity recycled lightweight aggregate concrete as described in any one of claims 1 to 7, characterized in that, This method includes the following process: In a high, narrow, long and narrow fat groove, use segmented formwork to block and use a pump truck to pour high-fluidity recycled lightweight aggregate concrete without vibration to complete the backfill of the high, narrow, long and narrow fat groove. The depth of the high, narrow, long and narrow fat groove is greater than 12m, and the width is greater than 1.2m.

9. The method according to claim 8, characterized in that The process of the segmented formwork blocking meets the following conditions: Adopt layered stepped gradual retreat pouring. When pouring each layer of high-fluidity recycled lightweight aggregate concrete, stagger a step of 0.8m to 1.2m with the next layer. The thickness of each layer is 250mm to 350mm. When pouring the lower layer of high-fluidity recycled lightweight aggregate concrete, bury multiple steel bars at the step, and the spacing of the steel bars is 400mm to 600mm, the buried length is 200mm to 300mm, and the exposed length is 80mm to 100mm. When pouring the upper layer of high-fluidity recycled lightweight aggregate concrete, set up formwork at the position of the steel bars and support the formwork with square timbers and steel pipes.

10. The method according to claim 8, characterized in that, When casting the high-fluidity recycled lightweight aggregate concrete, waterproof construction is carried out on the outer wall of the high, narrow, long and narrow fat groove, and the height of the waterproof construction is greater than the height of the cast high-fluidity recycled lightweight aggregate concrete. The free fall height of the high-fluidity recycled lightweight aggregate concrete during casting does not exceed 2m.

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