CN103013526B - Soil solidifier and soil solidification method - Google Patents

Abstract

The invention relates to a soil curing agent and a soil curing method. The soil curing agent contains 15-30% of fly ash, 4-15% of lime, 10-20% of water glass, 8-20% of caustic soda, 5-16% of gypsum, 10-32% of ordinary Portland cement, fluorite 0.5-3.5%, sodium sulfate 0-1.5%. When the soil curing agent solidifies the soil, it solidifies tightly, with low shrinkage and expansion coefficients. The shrinkage of the consolidated soil is extremely small, and it is not easy to be deformed and cracked by thermal expansion and contraction caused by temperature changes. Therefore, the impermeability of the solidified soil, It has good anti-freeze and anti-crack performance, which better solves the problems of poor water stability, large dry shrinkage, and easy cracking when traditional solidification materials solidify soil, and the consolidated soil has good heat insulation function. The soil solidification method of the invention is simple and convenient in construction, saves time and labor, uses the solidifying agent without being affected by temperature, has fast solidification time, high work efficiency, and can greatly shorten the construction period and reduce the cost.

Description

Soil stabilizer and soil stabilizer method

technical field

The invention relates to the technical field of civil engineering, in particular to a soil curing agent and a soil curing method.

Background technique

Soil solidification is actually physical and chemical treatment of the soil with external admixtures to change the composition of the soil and the engineering properties of the soil, so as to achieve the purpose of improving soil strength and soil compaction. The fly ash soil curing agent is mainly composed of fly ash, which is a hydraulic cementitious material prepared from a variety of inorganic and organic materials after reasonable matching. It belongs to a new type of building material and can be directly cemented at room temperature. Soil particles may be able to react with clay minerals to form gelling substances.

At the beginning of the 20th century, due to the needs of construction of roads and ports, some economically developed countries used lime and cement to improve the soil, and achieved good results in the initial stage of construction. However, in the long-term soil stabilization projects, people gradually realized that simply using Traditional soil solidification materials such as lime and cement have obvious deficiencies and cannot meet the needs of engineering construction development. Therefore, it is very necessary to look for soil solidification materials with the characteristics of stable soil solidification, good water stability, small shrinkage and expansion, non-toxic and harmless, energy saving, and easy construction.

With the rapid development of highway construction in my country, the demand for cost-effective soil curing agents is becoming increasingly apparent. Although there are many types of soil curing agents currently on the market, the following problems generally exist:

①The compressive strength does not meet the industry standard. my country's roads are divided into five grades and two standards. Expressways and first-class roads require the 7-day saturated compressive strength of the solidified soil to be above 5MPa, and second-, third-, and fourth-grade roads require the day-saturated compressive strength of the solidified soil to be greater than 3MPa ( CJJ/T801998). Soil stabilizers that have been used in road construction can only make up for their strength by increasing their dosage.

②The price is expensive. There are very few domestic soil stabilizer manufacturers in my country, only a few production units in Beijing and Tianjin, and a large number of them are imported from the United States, Japan, and Australia, which greatly increases the cost. The price of soil stabilizer sold in the market is basically above 1800 yuan.

③Water resistance is not good enough. The water stability of the soil curing agent that has been constructed is not enough, especially the water agent, which cannot consolidate the foundation soil after soaking in rainwater for a long time.

Therefore, seeking high-strength and cheap raw materials, exploring the curing mechanism, improving the compressive strength and water resistance of soil curing agents, reducing material prices, realizing waste utilization, and improving the convenience of construction have become urgent tasks in the industry.

Contents of the invention

The technical problem to be solved by the present invention is to provide a soil curing agent that can solidify soil, has high compressive strength, good water and moisture resistance, and cheap raw materials, and discloses a soil curing agent that is simple in construction and high in working efficiency. method.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

Design a kind of soil curing agent, in terms of weight percentage, containing 15-30% of fly ash, 4-15% of lime, 10-20% of water glass, 8-20% of caustic soda, 5-16% of gypsum, ordinary silicate Cement 10-32%, fluorite 0.5-3.5%, sodium sulfate 0-1.5%.

The soil curing agent contains 15-25% of fly ash, 8-12% of lime, 12-18% of water glass, 12-18% of caustic soda, 10-15% of gypsum, 15-25% of ordinary portland cement, firefly Stone 1.0-2.0%, sodium sulfate 0-1.0%.

The soil curing agent contains 19% of fly ash, 10% of lime, 16% of water glass, 16% of caustic soda, 13% of gypsum, 23.5% of ordinary Portland cement, 1.5% of fluorite, and 1.0% of sodium sulfate.

The specific surface area of the fly ash is 1.70×10 ⁴ to 1.90×10 ⁴ cm ² /g.

The lime at least meets the relevant requirements of the third grade slaked lime in the national standard GB1594-79.

The fluorite conforms to the national standard GB19321-88.

A kind of method utilizing above-mentioned soil solidifying agent to carry out soil solidification, main step comprises:

Prepare the lower bearing layer, construction measurement, material preparation, paving, mixing, leveling and rolling forming, and initial maintenance. In the material preparation step, prepare the raw materials of the soil curing agent according to the above-mentioned soil curing agent raw material ratio; In the above mixing step, the water content of the soil is adjusted to 10-20%, and the soil curing agent is mixed at a mixing ratio of 1:14-20.

In the mixing step, the moisture content of the soil is preferably adjusted to 15.5%, and the soil stabilizer is mixed at an optimal mixing ratio of 1:17.

The present invention has positive and beneficial effects:

(1) The curing agent of the present invention contains activator components (such as caustic soda, sodium sulfate, etc.), which can activate the surface of the curing agent particles and soil particles. During the hydration reaction process, the specific surface area of the curing agent itself increases greatly, and is suitable for It is suitable for the soil with a small solidified particle size range; the soil solidifying agent of the present invention not only exerts the hydration reaction and ion exchange effect in the past, but also greatly improves the compressive strength of the solidified soil by stimulating the activity of the soil itself, and has better Waterproof and moisture-proof, the cured soil will not appear "secondary muddy" phenomenon.

(2) When the soil curing agent of the present invention solidifies the soil, it solidifies tightly, has low shrinkage and expansion coefficients, and the relative shrinkage of the consolidated soil is extremely small, and it is not easy to cause deformation and cracking due to thermal expansion and contraction due to changes in temperature. Therefore, the anti-seepage, anti-freeze, and crack resistance of the solidified soil are good, and the problems of poor water stability, large drying shrinkage, and easy cracking that exist when the traditional solidification material solidifies the soil are better solved.

(3) Thermal conductivity is extremely small. The soil solidifying agent of the invention has strong coagulation and solidification effect, the solidification surface is compact, and has good heat insulation function and cooling function.

(4) The raw materials used are non-toxic, harmless and energy-saving. If a large amount of industrial waste—fly ash is used, it has double energy-saving effects and is non-toxic. At the same time, it can be directly used for industrial fly ash and industrial waste residue. When used to seal harmful materials, harmful substances should not seep out, and the safety is good.

(5) The soil solidification method of the present invention is easy to construct, saves time and effort, is not affected by temperature when using the solidifying agent, has fast solidification time, high work efficiency, can greatly shorten the construction period and reduce the cost. The construction site using the curing agent of the present invention can obtain local materials without occupying space, and avoid vehicles transporting waste soil from affecting traffic and polluting the surrounding environment.

(6) It can be applied to ground engineering such as roads, streets, and airports for different soil properties. One of the most widely used applications is the application in road subgrades.

(7) Under the condition of the formula of the present invention, the cost of soil curing agent is about 530 yuan/ton, while the current market price of conventional soil curing agent is about 1800 yuan/ton.

Description of drawings

Fig. 1 is the relationship diagram of the dry density-water content-soil solidifying agent dosage of soil among the present invention.

Detailed ways

The present invention is further described below in conjunction with specific examples. All raw materials involved in the following examples are commercially available raw materials unless otherwise specified.

The raw material formula of soil solidifying agent in embodiment 1～18 is shown in Table 1, and the index requirement of main raw material is as follows:

Fly ash: The specific surface area of the factory fly ash is 1.85×10 ⁴ cm ² /g, and its particle size distribution is shown in Table 1 below.

Table 1 Particle size distribution of fly ash

Mix fly ash and water at a mass ratio of 4:1 and wet grind them with a ceramic ball mill.

Lime: Refer to the national standard (GB1594-79), use slaked lime, three grades.

Portland cement: choose ordinary Portland cement, the components of which are as follows: 3CaO·SiO ₂ (46%), 2CaO·SiO ₂ (32%), 3CaO·AL ₂ O ₃ (12%), 4CaO·Al ₂ O ₃ ·Fe ₂ O ₃ (10%); the factory cement passes through a 0.080mm round hole sieve, and the sieve residue is less than 4%.

Water glass: commonly known as sodium silicate, is a water-soluble silicate, and its aqueous solution is water glass. The water glass used is an aqueous solution of sodium silicate (Na ₂ O·nSiO ₂ ).

Gypsum: Natural dihydrate gypsum (CaSO ₄ ·2H ₂ O), also known as raw gypsum, can be calcined and ground to obtain β-type hemihydrate gypsum (CaSO ₄ ·1/2H ₂ O), that is, building gypsum.

Fluorite, also known as fluorite. Choose according to the national standard GB19321-88 of fluorite in my country's building materials industry.

Caustic soda and sodium sulfate are common commercially available raw materials.

Blend the above-mentioned various raw materials together according to the formula ratio in Table 2, and fully stir them with a mixer. After stagnation for 5 to 10 minutes, stir again evenly. After 12 hours, it can be used; it can also be used without Packed in breathable plastic bags. Stored for use, the storage period is 12 months.

The inspection of the performance index of the soil stabilizer in the above-mentioned examples is carried out according to the regulations in the industry standard soil stabilizer CJ/T3073-1998, and its compressive strength index is shown in Table 1 (the soil dry density index can reach 1.80g/cm ³ , The optimum moisture content is 15.5%).

Table 2 Soil stabilizer formula table

The above examples of soil stabilizers have been tested many times in the laboratory and in the field, and the main physical indicators of the stabilized soil are shown in Table 3.

Table 3 Main indicators of solidified foundation soil

Specific gravity (g/m ³ ) Liquid limit% Plastic limit% plasticity index soil type (1.69) 27.8 16.2 11.6 Powder sand soil ~ sandy loam soil

Field experiments have proved that the soil curing agents in the above examples can be applied to the soil consolidation treatment of second, third, and fourth grade roads, and can also be used for soil consolidation of expressways and first grade road subbases.

Embodiment 19: Maximum dry density and compressive strength test of soil stabilizer

(1) Soil maximum dry density experiment

1. according to the preparation method of formula described in embodiment 1 and curing agent, prepare soil curing agent;

②Add the weighed curing agent to the soaked soil sample, fully mix it with a stirrer to a uniform state, and place it for 12 hours;

③According to the requirements of TO804-94 in JTJ057-94, select the heavy-duty test method, and prepare soil samples according to the water content of 10%, 12%, 14%, 16%, 18%, and 20% respectively; use the instrument to detect the soil of the test piece dry density; and dot-plot soil dry density-water content diagram, see Figure 1.

④ The optimal soil water content under the maximum dry soil density can be found from Figure 1. The maximum dry density of the soil is 1.80g/cm ³ , and the optimal water content is 15.5%.

(2) Compressive strength test

①Use the method of soil drilling to take out the soil specimen;

The amount of solidified soil material required for a specimen is calculated by the following formula:

The moisture content of the mixture (%).

②Put the test piece on the lifting platform of the hydraulic press to measure the compression resistance. During the measurement process, the deformation rate of the test piece should be kept at about 1mm/min, and the maximum pressure when the test piece is destroyed should be recorded.

③Calculation of compressive strength

The unconfined compressive strength P of the solidified soil specimen is calculated by the following formula

P =F/A= 0.00051P (MPa)

In the formula: F refers to the maximum pressure (N) when the specimen is destroyed, A refers to the bottom area of the specimen, A=πD ² /4, and D refers to the diameter of the bottom surface of the specimen (mm).

④ The experimental results prove that the saturated compressive strength of the solidified soil with 8% fly ash soil stabilizing agent is 3.66MPa.

It can be seen from the standard compaction test results that the maximum dry density of the solidified soil increases gradually with the increase of the content of the solidifying agent. When the mixing ratio of the solidifying agent is greater than 1:14, the maximum dry density of the solidified soil The maximum dry density of the compound increases obviously, and tends to a constant value with the gradual increase of the blending ratio, and the increase range is between 0.029 and 0.049g/cm ³ .

It can be seen that when the mixing ratio of the curing agent and the soil to be stabilized is 1:17, the maximum dry density of the consolidated soil is 1.80g/cm ³ , which is 0.05 higher than that of the plain soil (1.75g/cm ³ ). g/cm ³ , the change is relatively obvious, which plays a very obvious role in improving the strength of the soil, and then it shows a downward trend. It can be concluded that the optimum blending amount of fly ash soil stabilizer is 5.88% (equivalent to 1:17), the optimum water content is 15.5%, and the maximum dry density of soil can reach 1.80g/cm ³ .

Although the present invention has been described in detail with general descriptions and specific embodiments above, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims (8)

1. A soil solidifying agent, characterized in that, in weight percent, said soil solidifying agent consists of fly ash 15～30%, lime 4～15%, water glass 10～20%, caustic soda 8～20%, Composed of 5-16% gypsum, 10-32% ordinary Portland cement, 0.5-3.5% fluorite and 0-1.5% sodium sulfate. 2. soil curing agent according to claim 1, is characterized in that, described soil curing agent is made of fly ash 15～25%, lime 8～12%, water glass 12～18%, caustic soda 12～18%, Composed of 10-15% gypsum, 15-25% ordinary Portland cement, 1.0-2.0% fluorite and 0-1.0% sodium sulfate. 3. soil solidifying agent according to claim 1, is characterized in that, described soil solidifying agent is made of fly ash 19%, lime 10%, water glass 16%, caustic soda 16%, gypsum 13%, common silicate It is composed of 23.5% cement, 1.5% fluorite and 1.0% sodium sulfate. 4. The soil stabilizer according to claim 1, characterized in that the specific surface area of the fly ash is 1.70×10 ⁴ to 1.90×10 ⁴ cm ² /g. 5. The soil consolidation agent according to claim 1, characterized in that the lime at least meets the relevant requirements of the third grade slaked lime in the national standard GB1594-79. 6. The soil curing agent according to claim 1, wherein the fluorite complies with the national standard GB19321-88. 7. soil solidifying agent according to claim 1, is characterized in that, utilizes soil stabilizing agent to carry out the method for soil solidifying, and main step comprises: prepare lower bearing layer, construction measurement, stock preparation, paving, mixing, leveling and Roll forming, initial maintenance, it is characterized in that, in described preparation step, prepare each raw material of soil curing agent according to the raw material ratio described in claim 1; In described mixing step, soil water content is adjusted to 10 ～20%, and mix the soil solidifying agent described in claim 1 at a mixing ratio of 1:14～20. 8. soil solidifying agent according to claim 7, is characterized in that, in described mixing step, soil water content is adjusted to 15.5%, and mix described soil solidifying agent by the mixing ratio of 1:17 .