High performance drag reduction solidified mud and preparation method thereof

Abstract

The invention discloses a high-performance drag-reducing solidifying mud and a preparation method thereof. The high-performance drag-reducing solidifying mud comprises the following components by mass: 120-160 parts of cement, 250-300 parts of floating beads, 60-100 parts of bentonite, 1-3 parts of fluid loss reducer, 6-12 parts of swelling agent, 0.5-1.5 parts of polyvinyl alcohol, 0.2-0.6 parts of nanoemulsion, and 600-680 parts of water. The invention can reduce the interface friction coefficient through the lubrication effect of the nanoemulsion, and the ball effect of the floating beads and the foaming effect after the addition of polyvinyl alcohol can convert the sliding friction into rolling friction, greatly improving the lubrication and drag-reducing performance of the mud. In the later stage, as the cement hydration proceeds and the chemical reaction of polyvinyl alcohol and nanoemulsion proceeds, the mud gradually solidifies to form a solidified body with a certain strength, which can avoid the mud replacement process after pile pressing, shorten the entire pile pressing period, and improve the construction efficiency.

Description

Technical Field

[0001] The invention relates to the field of static pile pressure engineering, and in particular to a high-performance drag-reducing solidified mud and a preparation method thereof. Background Art

[0002] During the construction of static pile pressure, grouting is required to reduce the friction resistance of the outer wall of the pile during pile sinking. The principle is to inject drag-reducing mud around the pile foundation. The slurry lubricates the friction between the pile body and the soil in a fluid form, thereby reducing the propulsion resistance; at the same time, it plays a filling and supporting role. After the slurry solidifies, it forms a gel, which can effectively support the gap between the pile body structure and the surrounding soil body, and maintain the balance of mud, water and soil pressure around the pile body during the pile sinking process. At present, there are two types of commonly used grouting lubricating materials: one is mainly bentonite, and the other is artificially synthesized polymer materials. Bentonite is still the main lubricating material in jacking construction. However, at present, both the drag-reducing mud prepared by bentonite and polymer materials have the disadvantage of insufficient strength, and the mud is not easy to discharge, and it is easy to form a layer of mud skin between the pile and the soil, reducing the friction between the pile and the soil, resulting in insufficient bearing capacity of the pile foundation.

[0003] Therefore, it is necessary to develop a cement-based drag-reducing solidifying mud to solve the problems of poor drag-reducing and lubricating effect during static pile driving and reduced bearing capacity of the mud on the pile foundation after the pile driving is completed. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the above-mentioned background technology and provide a high-performance drag-reducing solidified mud and a preparation method thereof. The drag-reducing solidified mud has good drag reduction, stability and low shrinkage. The mechanical properties after solidification meet the engineering requirements and ensure the bearing capacity of the pile foundation.

[0005] The technical solution of the present invention is: a high-performance drag-reducing solidifying mud, characterized in that it includes the following components in parts by mass: 120-160 parts of cement, 250-300 parts of floating beads, 60-100 parts of bentonite, 1-3 parts of filtration reducer, 6-12 parts of swelling agent, 0.5-1.5 parts of polyvinyl alcohol, 0.2-0.6 parts of nanoemulsion, and 600-680 parts of water.

[0006] Preferably, the cement is PO42.5 ordinary Portland cement.

[0007] Preferably, the particle size of the floating beads is ≥120 mesh.

[0008] Preferably, the bentonite is sodium bentonite with a particle size of ≥200 mesh.

[0009] Preferably, the fluid loss reducer is one or more of carboxymethyl cellulose CMC, polyanionic cellulose PAC, polyacrylamide PAM, xanthan gum and the like.

[0010] Preferably, the expansion agent is one or more of CaO and MgO.

[0011] Preferably, the polyvinyl alcohol is in powder form with a molecular weight of 84,000 to 89,000.

[0012] Preferably, the nanoemulsion may be a nano-styrene-acrylic emulsion with a solid content of 40 to 50 wt % or a nano-silicone-acrylic emulsion with a solid content of 45 to 50 wt %.

[0013] Preferably, the present invention comprises the following components in parts by mass: 150-160 parts of cement, 250-265 parts of floating beads, 80-100 parts of bentonite, 1-2 parts of filtrate reducer, 6-9 parts of expansion agent, 1-1.5 parts of polyvinyl alcohol, 0.4-0.6 parts of nanoemulsion and 650 parts of water.

[0014] The present invention also provides a method for preparing any of the above high-performance drag-reducing solidified muds, comprising the following steps:

[0015] In a mixer, all powder materials including cement, floating beads, bentonite, expansion agent, fluid loss reducer and polyvinyl alcohol are mixed and stirred for 30 to 60 seconds. After the nanoemulsion is mixed with water, it is added into the mixer and stirred for 2 to 5 minutes to obtain a high-performance drag-reducing solidified mud.

[0016] The cement-based drag-reducing solidifying mud prepared by the present invention has good drag-reducing effect, excellent working performance and adjustable strength, and can greatly reduce the friction coefficient during pile driving, thereby improving construction efficiency and shortening construction time; at the same time, the mud can solidify by itself, and the solidified mud has a strength slightly greater than that of the soil around the pile, thereby overall improving the safety and stability of the pile foundation during the load transfer process.

[0017] The present invention has at least the following beneficial effects:

[0018] 1. The lubrication effect of nanoemulsion can reduce the interfacial friction coefficient. The rolling effect of the floating beads and the foaming effect after the addition of polyvinyl alcohol can convert sliding friction into rolling friction. The synergistic effect of the three can greatly improve the lubrication and drag reduction performance of the mud.

[0019] 2. Add expansion agent to the drag-reducing solidifying mud to reduce the shrinkage of the drag-reducing solidifying mud, ensure the load transfer between the pile and the soil, and improve the bearing capacity and stability of the pile foundation.

[0020] 3. The initial role of polyvinyl alcohol is to improve the lubrication performance of the mud, and the later role is to improve the bonding strength of cement, thereby improving the strength of the mud. At the same time, polyvinyl alcohol can reduce the interfacial tension, making it easier for the nanoemulsion to form a film, and the mechanical properties after film formation are excellent, which guarantees the mechanical properties of the entire mud system in the later stage.

[0021] 4. The mud material of the present invention has both lubrication and reinforcement effects, which can accelerate the efficiency of pile driving, and at the same time eliminate the mud replacement process after pile driving, thereby realizing a new pile driving process, shortening the entire pile driving period, and improving construction efficiency. DETAILED DESCRIPTION

[0022] The following specific examples further illustrate the present invention in detail. The drugs used in the examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified. In the following examples, the cement, floating beads, expansion agent, anti-filtration agent, and polyvinyl alcohol used are all powdered, the cement is PO42.5 ordinary Portland cement, the floating beads have a particle size of 120-200 mesh, the sodium bentonite has a particle size of 200-400 mesh, the polyvinyl alcohol has a molecular weight of 84000-89000, the CMC viscosity (2wt% aqueous solution, 25°C) is ≥5000mp·s, the PAC viscosity (2wt% aqueous solution, 25°C) is 58000-62000mp·s, and the PAM molecular weight is ≥18 million.

[0023] Example 1

[0024] The present embodiment provides a high-performance drag-reducing solidifying mud, comprising the following components in parts by mass: 140 parts of cement, 280 parts of floating beads, 80 parts of sodium bentonite, 3 parts of filtrate reducer (specifically CMC), 12 parts of swelling agent (specifically CaO), 0.5 parts of polyvinyl alcohol, 0.2 parts of nanoemulsion (specifically nano-silicone acrylic emulsion with a solid content of 48wt%), and 650 parts of water.

[0025] Example 2

[0026] The present embodiment provides a high-performance drag-reducing solidifying mud, comprising the following components in parts by mass: 150 parts of cement, 265 parts of floating beads, 80 parts of sodium bentonite, 2 parts of filtrate reducer (specifically PAC), 9 parts of swelling agent (specifically CaO), 1 part of polyvinyl alcohol, 0.4 parts of nanoemulsion (specifically nano-styrene-acrylic emulsion with a solid content of 46wt%), and 650 parts of water.

[0027] Example 3

[0028] The present embodiment provides a high-performance drag-reducing solidifying mud, comprising the following components in parts by mass: 160 parts of cement, 250 parts of floating beads, 100 parts of sodium bentonite, 1 part of filtrate reducer (specifically CMC), 6 parts of swelling agent (specifically CaO), 1.5 parts of polyvinyl alcohol, 0.6 parts of nanoemulsion (specifically nano-styrene-acrylic emulsion with a solid content of 46wt%), and 650 parts of water.

[0029] Example 4

[0030] The present embodiment provides a high-performance drag-reducing solidifying mud, comprising the following components in parts by mass: 120 parts of cement, 300 parts of floating beads, 60 parts of sodium bentonite, 1 part of filtration reducer (specifically PAM), 9 parts of swelling agent (specifically MgO), 1.5 parts of polyvinyl alcohol, 0.6 parts of nanoemulsion (specifically nano-silicone acrylic emulsion with a solid content of 48wt%), and 600 parts of water.

[0031] Example 5

[0032] The present embodiment provides a high-performance drag-reducing solidifying mud, comprising the following components in parts by mass: 140 parts of cement, 280 parts of floating beads, 80 parts of sodium bentonite, 3 parts of filtration reducer (specifically xanthan gum), 12 parts of swelling agent (specifically MgO), 0.5 parts of polyvinyl alcohol, 0.6 parts of nanoemulsion (specifically nano-styrene-acrylic emulsion with a solid content of 46wt%), and 650 parts of water.

[0033] The proportions of the components of the high performance drag reducing solidifying mud materials of the above Examples 1 to 5 are shown in Table 1 below.

[0034] Table 1 Amount of each component of high performance drag reduction solidified mud material of Examples 1 to 5

[0035]

[0036]

[0037] The preparation method of the high performance drag reduction solidified mud of the above embodiments 1 to 5 is as follows:

[0038] First, stir all the powder materials (cement, bentonite, floating beads, expansion agent, filtration reducer, polyvinyl alcohol) in a mixer for about 30 seconds to mix them evenly, then dissolve the nanoemulsion in water and add it to the mixer for stirring for 2 minutes. Stop stirring after high-speed stirring.

[0039] Comparative Example

[0040] A comparative slurry was obtained by mixing 140 parts of cement, 280 parts of fly ash, 80 parts of bentonite and 650 parts of water in parts by mass.

[0041] Performance Testing

[0042] The high performance drag reduction solidified mud obtained in Examples 1 to 5 and the comparative mud were tested according to the following test method. The test results are shown in Table 2.

[0043] Test method:

[0044] The test methods for 28d compressive strength, setting time and volume shrinkage of drag-reducing solidified mud refer to JGJ / T70-2009 "Standard for Test Methods for Basic Properties of Building Mortar".

[0045] Viscosity coefficient test: Use mud viscosity coefficient tester (Shandong Meike Instrument NZ-3A).

[0046] The determination of water loss and mud thickness refers to TGT F50-2011 "Technical Specifications for Highway Bridge and Culvert Construction".

[0047] Table 2 Performance parameters of mud in Examples 1 to 5 and Comparative Examples

[0048]

[0049]

[0050] The test results show that the mud prepared in the comparative example has poor drag reduction effect, strength after solidification, anti-filtration and anti-shrinkage properties, and is difficult to meet the needs of engineering construction; the drag reduction solidification mud prepared by the present invention has significantly improved properties. From the results of Examples 1 to 3, it can be seen that with the replacement of fly ash with floating beads and the increase of polyvinyl alcohol and nanoemulsion, the viscosity coefficient of the mud gradually decreases, that is, the drag reduction effect is getting better and better, and the strength in the later stage also gradually increases, indicating that the floating beads, polyvinyl alcohol and nanoemulsion have a significant improvement effect on the mechanical properties and drag reduction and lubrication properties of the mud. By adding filtration reducers and swelling agents, the water loss, mud skin thickness and volume shrinkage rate of the mud are significantly reduced, indicating that the mud filtration loss and volume shrinkage are small. By comparing Example 1 with Example 5, it can be seen that when the dosage of floating beads and polyvinyl alcohol remains unchanged and the dosage of nanoemulsion is increased alone, the lubrication performance of the mud is improved slightly, indicating that when the dosage of nanoemulsion and polyvinyl alcohol is maintained at a certain ratio, the lubrication performance and mechanical properties of the mud will be significantly improved, reflecting the synergistic effect of nanoemulsion and polyvinyl alcohol. Therefore, when preparing drag-reducing and solidifying mud, special attention should be paid to the proportion of various materials to maximize the advantages of the materials.

[0051] The above test results show that high-performance drag-reducing solidified mud can be prepared by mixing large amounts of floating beads, filtration reducers, swelling agents, polyvinyl alcohol and nanoemulsions.

Claims

1. A high-performance drag-reducing solidified mud, characterized in that: The invention comprises the following components by weight: 120-160 parts of cement, 250-300 parts of floating beads, 60-100 parts of bentonite, 1-3 parts of fluid loss reducer, 6-12 parts of expansion agent, 0.5-1.5 parts of polyvinyl alcohol, 0.2-0.6 parts of nanoemulsion, and 600-680 parts of water; The particle size of the floating beads is ≥120 meshes, the expansion agent is one or more of CaO and MgO, the polyvinyl alcohol is in powder form with a molecular weight of 84000-89000, and the nanoemulsion is a nano styrene-acrylic emulsion with a solid content of 40-50wt% or a nano silicone-acrylic emulsion with a solid content of 45-50wt%.

2. The high performance drag reduction solidification mud according to claim 1, characterized in that: The cement is PO42.5 ordinary Portland cement.

3. The high performance drag reduction solidification mud according to claim 1, characterized in that: The bentonite is sodium-based bentonite with a particle size of ≥200 meshes.

4. The high performance drag reduction solidification mud according to claim 1, characterized in that: The fluid loss reducer is one or more of carboxymethyl cellulose CMC, polyanionic cellulose PAC, polyacrylamide PAM, xanthan gum and the like.

5. The method for preparing high-performance drag-reducing solidified mud according to any one of claims 1 to 4, characterized in that: The following steps are involved: In a mixer, all powder materials including cement, floating beads, bentonite, expansion agent, fluid loss reducer and polyvinyl alcohol are mixed and stirred for 30 to 60 seconds. After the nanoemulsion is mixed with water, it is added into the mixer and stirred for 2 to 5 minutes to obtain a high-performance drag-reducing solidified mud.

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