Novel filler flexible pile for foundation treatment and manufacturing method thereof

Abstract

The invention discloses a novel filler flexible pile for foundation treatment, the novel filler flexible pile is prepared from carbide slag, rice hull ash and plain soil according to the mass ratio of 1: 2: 7, and a manufacturing method comprises the following steps: fully and uniformly mixing the carbide slag, the rice hull ash and the plain soil according to the ratio of 1: 2: 7, backfilling the mixture into a pile hole, and fully tamping to obtain the flexible pile. Solid waste carbide slag and rice hull ash are used as a curing agent of the soil body of the flexible pile, after the solid waste carbide slag and the rice hull ash are evenly mixed with the soil body, the pile hole is backfilled and fully tamped in the pile hole, and therefore the novel flexible pile is formed and used for reinforcing a foundation or eliminating collapsibility of loess. On one hand, the lime consumption is saved, and on the other hand, waste resources can be recycled, so that the method has good application prospects.

Description

Technical Field

[0001] The present invention relates to flexible piles in composite foundations, specifically flexible piles added with carbide slag and rice husk ash, which are applicable to the field of civil engineering foundation, and are mainly used for the reinforcement and treatment of building and road foundations. Background Art

[0002] Flexible piles generally refer to piles formed by punching holes in the foundation by means of soil-extrusion hole formation or non-soil-extrusion hole formation, and then backfilling the holes with fillers in layers and tamping them layer by layer. According to different backfill materials, they are respectively called soil piles, lime-soil piles, rammed cement-soil piles, etc. Backfilling with plain soil is called the soil pile method; backfilling with lime-soil prepared by mixing lime (the main component is CaO) with soil is called the lime-soil pile method; backfilling with cement-soil prepared by mixing cement (the main active material is SiO2) with soil is called the rammed cement-soil pile method. Considering that both cement and lime consume huge amounts of natural resources and energy in their production processes, and emit a large amount of harmful substances such as dust, sulfur dioxide, and carbon dioxide, causing air pollution. It is imperative to seek substitutes for cement and lime and develop green and environmentally friendly cementitious materials for flexible piles.

[0003] Since carbide slag is rich in CaO and has strong alkalinity, while the main component of rice husk ash is SiO2, which has strong pozzolanic activity. Theoretically, it can be used as a substitute for lime and cement as a solidifying agent for soil. Through research, the present invention proposes to use the solid wastes in industrial production - rice husk ash and carbide slag to replace cement and lime and mix with soil to form flexible piles, and the flexible piles and the soil between the piles jointly form a composite foundation. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a new type of filler flexible pile for foundation treatment, which uses the solid wastes carbide slag and rice husk ash as the solidifying agent for the flexible pile soil. After being uniformly mixed with the soil, it is backfilled into the pile hole and fully tamped in the pile hole, thereby forming a new type of flexible pile for reinforcing the foundation or eliminating the collapsibility of loess.

[0005] To achieve the above object, the present invention provides the following technical solutions: A new type of filler flexible pile for foundation treatment, including the material and component mass ratio: carbide slag: rice husk ash: plain soil = 1:2:7.

[0006] Further requirements: the content of active calcium oxide CaO in the carbide slag is not less than 50%; the specific surface area of the rice husk ash is between 6000 - 7000 cm 2 / g; the plain soil is pure loess or cohesive soil or silt with a plasticity index greater than 4, and the content of organic matter shall not exceed 5%.

[0007] The method for making the novel flexible pile of filler comprises the following steps: (1) Treatment of carbide slag: First, dry the carbide slag and grind it in a universal crusher to obtain carbide slag powder, then sieve it to remove impurities. The content of active calcium oxide (CaO) is required to be no less than 50%; (2) Rice husk ash processing: The air-dried original rice husk ash is fully ground. The specific surface area of ​​the rice husk ash is between 6000-7000cm 2 / g between; (3) Soil selection: Choose pure loess, clay soil or silt soil with a plasticity index greater than 4, and the organic matter content shall not exceed 5%; (4) Mix the above calcium carbide slag, rice husk ash and plain soil in a ratio of 1:2:7 and fill them back into the pile hole and tamp them thoroughly to obtain a flexible pile. Beneficial Effects

[0008] The present invention uses solid waste rice husk ash and carbide slag instead of cement and lime to mix with soil to form flexible piles for reinforcing foundations or eliminating the collapsibility of loess. On the one hand, it saves lime usage, and on the other hand, it can also achieve the recycling of waste resources, so it has good application prospects. DETAILED DESCRIPTION

[0009] The mass ratio of carbide slag to rice husk ash is determined mainly by referring to the cementitious material "Cement Mortar Strength Test Method".

[0010] In order to determine whether the mixture of carbide slag and rice husk ash has gelling properties after adding water to it, seven ratios were selected for the two admixtures, namely 3:1, 2:1, 1.5:1, 1:1, 1:1.5, 1:2, and 1:3. The ratios were mixed with water to make gel samples for testing. Studies have shown that the mixture of carbide slag and rice husk ash has good gelling properties. To give full play to the gelling material function of the carbide slag / rice husk ash mixture, the amounts of the two need to be matched. If too much rice husk ash is added to the admixture, exceeding the required amount, some SiO2 activity will inevitably not be activated. If too much carbide slag is added, it will lead to excess Ca(OH)2, which will affect the hardening of the gel in a humid environment. The best ratio measured is 1:2.

[0011] The optimal proportion of fill is mainly determined by the unconfined compressive strength of the reinforced soil.

[0012] First, ensure that the mixing ratio of carbide slag and rice husk ash mixture is the optimal cementitious material ratio (1:2). Then, select 6 different mixing ratios of 5%, 10%, 15%, 20%, 25%, and 30% respectively for test preparation, calculate the required amounts of carbide slag-rice husk ash mixture and fill soil under different mixing ratios, and carry out mixing; after forming by static mechanical compaction method, use an electric demolding instrument for demolding and curing. Finally, test the unconfined compressive strength of the soil at the 28-day and 90-day curing periods after curing, and determine the optimal fill soil amount according to the strength. The actual measurement shows that when the mass mixing ratio range of carbide slag-rice husk ash mixture and soil is 20% - 30%, the strength of the cured soil is high. That is, when the ratio of carbide slag and rice husk ash mixture / fill soil amount is in the range of 2:8 - 3:7, the compaction strength is better. Considering the workability during construction and the sufficiency of the reaction of the cured soil, finally, the mixing ratio of carbide slag and rice husk ash mixture / fill soil amount = 3:7 is selected as the optimal mix ratio of the fill soil.

[0013] Combined with the optimal ratio of carbide slag:rice husk ash being 1:2, so the final mix ratio of the three components in the present invention is carbide slag:rice husk ash:silty soil = 1:2:7.

[0014] 1) Hydration and hydrolysis reactions of carbide slag-rice husk ash Through the chemical composition analysis of carbide slag and rice husk ash, it can be known that the main component of carbide slag is calcium oxide (CaO), while the main component of rice husk ash is active silicon dioxide (SiO₂). After the two are mixed, no chemical reaction will occur in an anhydrous environment. When the carbide slag-rice husk ash-based cementitious material is placed in a humid environment, calcium oxide (CaO) immediately undergoes a hydration reaction with water to generate calcium hydroxide (Ca(OH)₂), and then Ca(OH)₂ continues to react with active SiO₂ in a hydrolysis reaction to generate calcium silicate hydrate. In addition, a small amount of aluminum oxide Al₂O₃ contained in carbide slag and rice husk ash, and Ca(OH)₂ will also undergo a chemical reaction with Al₂O₃ to generate calcium aluminate hydrate. The generated hydration products have a fibrous structure, high strength, and are insoluble in water.

[0015] 2) Ion exchange and granulation Clay fill soil, as a multiphase dispersion system, exhibits general colloid characteristics when combined with water. After the highest content of SiO₂ in the fill soil encounters water, it forms silicic acid colloid particles, whose surface is carried with sodium ions (Na + ) or potassium ions (K + ), and they can carry out equivalent adsorption exchange with calcium ions Ca 2+ in the calcium hydroxide (Ca(OH)₂) solution, making smaller soil particles form larger aggregates, thereby increasing the strength of the soil. This effect called water glue connection is the main reason for the hardening of lime soil.

[0016] The gel particles of carbide slag-rice husk ash cementitious materials after hydration have a large specific surface area, generate strong surface energy, and have strong adsorption activity, which can further combine the larger soil aggregates formed by ion exchange and close the gaps between the soil aggregates to form a solidified soil aggregate structure. It can also close the pores between the soil aggregates to form a strong connection. From a macroscopic point of view, the strength of the solidified soil can be further improved.

[0017] 3) Pozzolanic reaction As the hydration reaction progresses, a large amount of calcium ions are precipitated in the solution. When the amount exceeds the amount required for the above ion exchange, part or most of the silicon dioxide and aluminum oxide that make up the clay minerals can react chemically with the calcium ions in an alkaline environment to form water-insoluble stable crystalline compounds - hydrated calcium silicate and hydrated calcium aluminate, and gradually generate water-insoluble stable crystalline compounds.

[0018] 4) Carbonation Free Ca(OH)2 in the hydrate can absorb carbon dioxide in the air and water, undergo a carbonation reaction, and produce water-insoluble calcium carbonate (CaCO3). Calcium carbonate is a hard crystal, and its production can increase the strength of the solidified soil, but the rate of increase is very slow and the magnitude is very small.

[0019] In the process of solidifying fill, through the hydration and hydrolysis of the gel, the fine soil particles agglomerate, condense and harden, and the aggregated structure forms a dense overall structure, which greatly improves the strength. The method for making a novel flexible pile of filler material comprises the following steps: (1) Treatment of carbide slag: First, dry the carbide slag and grind it in a universal crusher to obtain carbide slag powder, then sieve it to remove impurities. The content of active calcium oxide (CaO) is required to be no less than 50%; (2) Rice husk ash processing: The air-dried original rice husk ash is fully ground. The specific surface area of ​​the rice husk ash is between 6000-7000cm 2 / g between; (3) Soil selection: Choose pure loess, clay soil or silt soil with a plasticity index greater than 4, and the organic matter content shall not exceed 5%; (4) Mix the above calcium carbide slag, rice husk ash and plain soil in a ratio of 1:2:7 and fill them back into the pile hole and tamp them thoroughly to obtain a flexible pile.

[0020] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A new type of flexible pile with filler for foundation treatment, characterized in that: The mass ratio of materials and components is: carbide slag: rice husk ash: bare soil = 1:2:

7.

2. The novel filler flexible pile for foundation treatment according to claim 1, characterized in that: The content of active calcium oxide (CaO) in the carbide slag is not less than 50%.

3. The novel filler flexible pile for foundation treatment according to claim 1, wherein: The specific surface area of the rice husk ash is between 6000-7000 cm 2 / g.

4. A novel filler flexible pile for foundation treatment according to claim 1, characterized in that: The plain soil is pure loess or clay soil or silt soil with a plasticity index greater than 4, and the organic matter content thereof shall not exceed 5%.

5. A manufacturing method of a new type of flexible pile with a filler for foundation treatment, characterized in that, The following steps are involved: (1) Treatment of carbide slag: First, dry the carbide slag and grind it in a universal crusher to obtain carbide slag powder, then sieve it to remove impurities. The content of active calcium oxide (CaO) is required to be no less than 50%; (2)Treatment of rice husk ash: The air-dried original rice husk ash is fully ground, and the specific surface area of the rice husk ash ranges from 6000 to 7000 cm 2 / g; (3) Soil selection: Choose pure loess, clay soil or silt soil with a plasticity index greater than 4, and the organic matter content shall not exceed 5%; (4) Mix the above calcium carbide slag, rice husk ash and plain soil in a ratio of 1:2:7 and fill them back into the pile hole and tamp them thoroughly to obtain a flexible pile.