CN115745519A - Foamed light soil based on expansive soil and industrial solid waste and preparation method thereof - Google Patents

Abstract

The invention relates to a foamed lightweight soil based on expansive soil and industrial solid waste and a preparation method thereof, belonging to the technical field of civil engineering materials. The raw material composition of the foam light soil includes expansion, cement, carbide slag, blast furnace slag, water, and foaming agent; the raw material composition is 300-500 parts by weight of expansive soil, 100-400 parts of cement, and 50-150 parts of calcium carbide slag 100-350 parts of blast furnace slag, 400-600 parts of water, 1-2 parts of blowing agent. In view of the lack of effective ways for expansive soil improvement and large-scale utilization, the present invention proposes an operation method for preparing foamed lightweight soil by using expansive soil and industrial solid waste, thereby effectively promoting the development and application of foundation treatment technology and promoting The consumption of expansive soil and industrial solid waste saves land resources and turns waste into treasure.

Description

A kind of foam light soil based on expansive soil and industrial solid waste and its preparation method

technical field

The invention relates to a foam light soil based on expansive soil and industrial solid waste and a preparation method thereof, belonging to the technical field of civil engineering materials.

Background technique

Expansive soil, also known as "expansive soil", is a cohesive soil that expands violently after soaking in water and shrinks significantly after dehydration. Because the soil contains more clay minerals such as montmorillonite and illite, it is very hydrophilic. When the natural moisture content is high, the expansion amount and expansion force after soaking in water are small, but the shrinkage amount and shrinkage force after dehydration are large, which will cause serious damage to buildings, but the strength is average in the natural state. Taller, less compressible, easily mistaken for a better foundation. Expansive soils are distributed in southern and central parts of my country. At present, the research on the treatment of expansive soil is not perfect. In actual projects, complex pile foundations are used, or the expansive soil is cleaned and backfilled with high-quality soil. The project cost is high and the efficiency is low. In particular, the expansive soil after cleaning lacks effective utilization methods, and often can only be piled up in the muck field, occupying a huge amount of land resources.

The foam light soil is to fully foam the foaming agent mechanically through the foaming system of the foaming machine, and evenly mix the foam with the raw material slurry, and then pass through the pumping system of the foaming machine for cast-in-place construction or mold molding. A new type of lightweight thermal insulation material with a large number of closed pores formed by natural conservation. The research and application of this material has developed rapidly in recent years, and it is widely used in roadbed backfill, load reduction of underground structures, tunnel cavity grouting, old bridge reinforcement, sandwich component production, landscaping, emergency rescue and other fields.

At present, cement is mainly used as the cementitious material for foamed lightweight soil, but this preparation method has the disadvantages of high cost, high energy consumption, and large pollution, and does not conform to the principle of green environmental protection; at the same time, the foamed lightweight soil prepared by cement is easy to dry and crack, early The strength is poor, and the strength basically stops increasing after 7d to 14d, which limits the scope of its engineering application. Some typical industrial solid wastes have good properties. The calcium carbide slag produced by the ethylene industry can provide a large amount of calcium and an alkaline environment to promote the hydration gelation reaction; the blast furnace slag produced by ironmaking is rich in cementitious material components, which can It has a certain substitution effect on cement and has very high application potential.

Contents of the invention

technical problem:

In order to solve the above problems, the invention discloses a foamed lightweight soil prepared from expansive soil, cement, carbide slag and blast furnace slag as raw materials and a preparation method thereof. A large amount of expansive soil is used in the foam lightweight soil, and industrial solid waste is used to partially and effectively replace cement. It has the characteristics of reliable quality and simple construction, and can be used as an effective means for treating expansive soil.

Technical solutions:

The present invention adopts following technical scheme:

The invention provides a lightweight soil based on expansive soil and industrial solid waste foam, and its raw material composition includes: 300-500 parts of expansive soil, 100-400 parts of cement, 50-150 parts of carbide slag, and 100 parts of blast furnace slag -350 parts, 400-600 parts of water, 1-2 parts of foaming agent.

Preferably, the free expansion rate of the expansive soil is not less than 20%. The raw soil is air-dried, crushed and passed through a 2mm sieve. For raw soil that does not meet the requirements, deslagging and necessary screening should be performed in advance.

Preferably, the cement is Portland cement, ie typical industrial Portland cement.

Preferably, the main mineral components of the calcium carbide slag are calcium oxide and silicon dioxide, and contain a small amount of oxides of ^potassium , sodium, and iron metal elements; kg.

Carbide slag is solid waste produced by the acetylene industry. The mass fraction of calcium oxide in the main minerals is greater than 55%, and the mass fraction of silicon dioxide is greater than 30%.

Preferably, the main mineral components of the blast furnace slag are calcium oxide, silicon dioxide, aluminum oxide, and magnesium oxide; oxides containing a small amount of iron and titanium metal elements; the blast furnace slag needs to be pretreated by ball milling to reduce its surface area. Less than 250m ² /kg.

Blast furnace slag is solid waste produced by the iron and steel smelting industry. The main mineral components are more than 30% of the mass fraction of calcium oxide, more than 30% of the mass fraction of silicon dioxide, more than 10% of the mass fraction of aluminum oxide, and more than 10% of the mass fraction of magnesium oxide. Score greater than 5%.

Preferably, the water is tap water, purified water or distilled water, including water required for foaming.

Preferably, the foaming agent is rosin resins (rosin soap foaming agent, etc.), synthetic surfactants (sodium lauryl alcohol ether sulfate, sodium dodecylsulfonate, etc.), proteins (vegetable protein and Animal protein foaming agent), composite foaming agent (vegetable composite foaming agent, etc.), etc., any one or more mixtures. When using rosin resins and synthetic surface-active foaming agents, an appropriate amount of foam stabilizers can be mixed according to the situation, including but not limited to cellulose ether, lauryl alcohol, triethanolamine, calcium stearate, etc.

The present invention also provides a preparation method based on expansive soil and industrial solid waste foam light soil, the steps are as follows:

S1. Raw material preparation. Weigh raw materials as needed and set aside.

S2, slurry preparation. Put the expansive soil, cement, calcium carbide slag and blast furnace slag into the mixing device according to the proportion, and stir at a speed of not less than 120r/min for 2-3min to make the raw materials evenly mixed. Divide the water into 2 groups, one group is 30-100 times the number of foaming agent, the specific value should be determined according to the type of foaming agent, and set aside; the other group is divided into 2-3 parts, added to the mixture in turn, each time After adding water, it needs to be stirred for 1min-2min until the water is added. During the stirring process, pay attention to the mixture not sinking to the bottom or agglomerating to ensure that the slurry is uniform, without sedimentation, and without hanging on the wall.

S3, foam preparation. Dilute the foaming agent into water according to the dilution ratio, and stir slightly. Connect the mixed liquid to the foaming machine through a plastic tube, and then open the foam valve. Different foaming agents and different foaming agent dilution ratios have different optimal speed ratios for the pumps. Adjust the pressure and The water pump speed ratio, the control pressure range is 0.1mpa-0.4mpa, the water pump speed ratio is 20-80, and the corresponding water pump flow rate is 1L/min-4L/min, releasing fine and stable foam. Use a container to pick up the foam and set aside.

S4, mixing and stirring. Pour the foam into the slurry and stir. The stirring speed should be 100r/min-200r/min. It should not be too fast to avoid foam bursting. The stirring time is controlled at 10min-12min to ensure that the air bubbles are evenly distributed, and the slurry is fine and dense without sedimentation, that is, a well-mixed mixture can be obtained.

S5, sample preparation and maintenance. Immediately pour the mixed mixture into the mold, seal it, demould after 1d-2d, and maintain it in a standard curing room (relative humidity 99%, temperature 25°C) to a specified age, so as to obtain the foam lightness. quality soil.

Beneficial effect:

In view of the lack of effective ways for expansive soil improvement and large-scale utilization, the present invention proposes an operation method for preparing foamed lightweight soil by using expansive soil and industrial solid waste, thereby effectively promoting the development and application of foundation treatment technology and promoting The consumption of expansive soil and industrial solid waste saves land resources and turns waste into treasure.

The performance of expansive soil will significantly increase the cracking risk of engineering structures. After it is made into foam lightweight soil, the combination of fine pores and chemical composition can effectively reduce its dry shrinkage, so that it has good engineering application performance.

The present invention selects typical industrial solid waste carbide slag and blast furnace slag to partially replace cement as the cementitious material, and reduces the amount of cement by using the waste, thereby helping to reduce energy consumption and a large amount of CO ₂ , SO ₂ and Dust and other toxic substances are discharged, reducing environmental pollution and providing a new method for reducing carbon emissions.

The good synergistic performance of calcium carbide slag and blast furnace slag can effectively prevent the common cracking problem of cement-based foam light soil, and at the same time make the light soil have a certain early strength, and the strength can continue to increase with the growth of age, and the preparation method It is simple and can be applied to projects with special requirements to improve project safety.

Description of drawings

Fig. 1 is the flowchart of the preparation method of foam light soil of the present invention.

Fig. 2 is the appearance of the foamed lightweight soil prepared in Example 1.

Fig. 3 is the appearance of the foamed lightweight soil prepared in Example 2.

Fig. 4 is the appearance of the foam lightweight soil prepared in Comparative Example 1.

Detailed ways

In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the present invention is not limited to the following examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Example 1:

A kind of foam light soil based on expansive soil and industrial solid waste, the raw materials are selected according to the following mass fractions:

The expansive soil was taken from a construction site in Hefei, Anhui, 500 parts, and its basic properties are shown in Table 1. Pass through a 2mm sieve after being air-dried and pulverized.

Table 1 Basic properties of expansive soil

100 parts of carbide slag, 150 parts of blast furnace slag, the composition is shown in Table 2.

Table 2 The main components of calcium carbide slag and blast furnace slag (mass fraction%)

raw material Al₂O₃ SiO₂ CaO MgO Na₂O K₂O Fe₂O₃ TiO₂ other Carbide slag 1.36 32.14 65.51 - 0.06 0.02 0.41 - 0.50 blast furnace slag 15.76 36.21 38.14 8.51 - - 0.71 1.91 0.67

Conch 42.5 cement is selected as cement, 250 parts. The foaming agent selects 1 part of cement foaming agent with sodium dodecylbenzenesulfonate as the main raw material, and 100 parts of dilution water. Water selects tap water, except the dilution water quantity, the remaining water quantity is 500 parts.

The preparation method is as follows:

S1. Raw material preparation. According to the embodiment, after the required raw materials are measured, they are set aside.

S2, slurry preparation. Put the powder into the mixing device according to the proportion, and stir at a speed of 120r/min for 2min to make it fully mixed. Divide 500 parts of water into 3 parts, put them into the stirring device in turn, and stir for 2 minutes after each time, until the water is added. During the stirring process, pay attention to the mixture not sinking to the bottom or agglomerating, so as to ensure that the slurry is uniform, without sedimentation, and without hanging wall.

S3, foam preparation. Dilute foaming agent into water and stir slightly. Connect the mixed liquid to the foaming machine through a plastic tube, then open the foam valve, control the pressure range to 0.2mpa, and the specific speed of the water pump at 50, corresponding to the pump flow rate of 2L/min, to release fine and stable foam. Use a container to pick up the foam and set aside.

S4. Pour the foam into the slurry and stir, the stirring speed is 100r/min, and the stirring time is 10-min, to ensure that the bubbles are evenly distributed, and the slurry is fine and dense without sedimentation.

S5. Immediately pour the mixed material into the mold, seal it, demould after 2 days, and maintain it to the test age in a standard curing room (relative humidity 99%, temperature 25°C).

Example 2:

The difference between this embodiment and embodiment 1 is that the parts of cement are 100 parts, carbide slag is 150 parts, and blast furnace slag is 250 parts.

Comparative example 1:

The difference between this comparative example and Example 1 is that the parts of cement are 500 parts, carbide slag is 0 parts, and blast furnace slag is 0 parts. It should be pointed out that in Comparative Example 1, 33.3% of the samples with a curing age of more than 7 days showed cracking and fragmentation, and only uncracked samples were used in the test.

The properties of the foamed lightweight soil prepared in Examples 1, 2 and Comparative Example 1 were tested, and the results are shown in Table 3.

Table 3 foam lightweight soil performance test results

It can be seen from Table 3 that the unconfined compressive strength of Examples 1 and 2 is slightly lower than that of Comparative Example 1, but the volume shrinkage rate is better than that of Comparative Example 1. According to the China Engineering Construction Association standard CECS249:2008 "Technical Regulations for Cast-in-place Foam Lightweight Soil", the wet density and fluidity of Examples 1 and 2 all meet the requirements of the regulations, and the unconfined compressive strength can reach F1.0 and F0 respectively .6 level, can be applied in engineering.

Finally, the method of the present application is only a preferred embodiment, and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A foam light soil based on expansive soil and industrial solid waste, characterized in that: the raw material composition of foam light soil comprises expansion, cement, carbide slag, blast furnace slag, water, blowing agent; Raw material composition is by weight ratio: 300-500 parts of expansive soil, 100-400 parts of cement, Carbide slag 50-150 parts, 100-350 parts of blast furnace slag, 400-600 parts of water, Foaming agent 1-2 parts. 2. The foam light soil based on expansive soil and industrial solid waste according to claim 1, characterized in that: the free expansion rate of the expansive soil is not less than 20%. 3. The foam light soil based on expansive soil and industrial solid waste according to claim 1, characterized in that: the cement is Portland cement. 4. based on expansive soil and industrial solid waste foam light soil according to claim 1, it is characterized in that: described carbide slag is the solid waste that acetylene industry produces, and the massfraction of calcium oxide is greater than 55% in the carbide slag , The mass fraction of silicon dioxide is greater than 30%. 5. The foam light soil based on expansive soil and industrial solid waste according to claim 1, characterized in that: the blast furnace slag is the solid waste produced by the iron and steel smelting industry, and the mass fraction of calcium oxide in the blast furnace slag is greater than 30 %, the mass fraction of silicon dioxide is greater than 30%, the mass fraction of aluminum oxide is greater than 10%, and the mass fraction of magnesium oxide is greater than 5%. 6. based on expansive soil and industrial solid waste foam lightweight soil according to claim 1, it is characterized in that: described foaming agent is any in rosin resins, synthetic surface active class, protein, compound class foaming agent One or more mixtures. 7. A preparation method based on expansive soil and industrial solid waste foam light soil, characterized in that, the preparation method may further comprise the steps: S1. Raw material preparation: Weigh the raw materials as required and set aside; S2. Slurry preparation: Put expansive soil, cement, calcium carbide slag and blast furnace slag into the mixing device according to the proportion, and stir for 2-3 minutes at a speed of not less than 120r/min, so that the raw materials are evenly mixed to form a mixed dry material; Add water to the mixed dry material in turn, and stir for 1-2mins after adding water each time, until the water is added to form a slurry; S3. Foam preparation: add the foaming agent into water to dilute according to the dilution factor; connect the mixed liquid to the foaming machine through a plastic tube, then open the foam valve, adjust the pressure and pump speed ratio according to the demand, and release fine, For stable foam, use a container to pick up the foam and keep it for later use; S4, mixing and stirring: Pour the spare foam obtained in S3 into the spare slurry obtained in S2 and stir, and the mixed mixture is obtained after stirring; S5. Sample preparation and curing: pour the mixed material into the mold immediately, seal it, demould after 1d-2d, and cure it in a standard curing room to the specified age, and then obtain foamy light soil. 8. The preparation method based on expansive soil and industrial solid waste foam light soil according to claim 7, characterized in that, in S3, foaming agent is added into water and diluted by 30-100 times of foaming agent parts. 9. The preparation method based on expansive soil and industrial solid waste foam light soil according to claim 7, characterized in that, the control pressure range of the foam valve in S3 is at 0.1mpa-0.4mpa, and the specific speed of the water pump is at 20-80 , the corresponding pump flow is 1L/min-4L/min. 10. The preparation method based on expansive soil and industrial solid waste foam light soil according to claim 7, characterized in that, in S4, the stirring speed is 100-r/min 200r/min, and the stirring time is controlled at 10min-12min.

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