Composite soil stabilizer based on solid waste and pavement method thereof

Abstract

The invention discloses a composite soil stabilizer based on solid waste and a pavement method thereof, the composite soil stabilizer is composed of a powder component, a liquid component and a fiber reinforcement, the powder component is prepared from steel slag, desulfurized fly ash, rice hull ash and gypsum; the liquid component is prepared from water, sodium sulfate, sodium hydroxide and water glass; and the fiber reinforcement body is polypropylene plastic. The composite soil curing agent taking the steel slag, the desulfurized fly ash and the rice hull ash as main raw materials is used in road construction, and soil is cured by utilizing the synergistic effect of all the components. Besides, polypropylene plastic waste is added on the basis to improve the curing effect, so that the purposes of treating waste with waste and turning waste into wealth can be achieved, special soil with poor engineering performance can be effectively cured, and remarkable economic, social and environmental effects are achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of road construction, and specifically relates to a composite soil solidifying agent based on solid waste and a road use method thereof. Background Art

[0002] In infrastructure construction activities, we often encounter some special soils. These soils have poor mechanical properties and are not allowed to be used directly as roadbed filling materials. They should be solidified before use. At present, the main soil solidifiers used in the world are still cement, lime or gravel. Whether it is cement or lime, high carbon emissions will be generated during the production process. It is estimated that the production of 1 ton of cement will produce 0.9 tons of carbon dioxide, while the production of 1 ton of lime will produce 1.2 tons of carbon dioxide, which is extremely unfriendly to the environment and contrary to the concept of green development. With the increasingly serious environmental problems in the world, people pay more and more attention to environmental protection and resource recycling. How to achieve green economy and low-carbon economy in soil solidification is a key issue that needs to be solved urgently.

[0003] Steel slag and desulfurization ash are both by-products of the steelmaking process. China's steel slag stockpile has exceeded 1 billion tons, but the utilization rate is less than 20%. Its mineral composition is mainly tricalcium silicate, dicalcium silicate, dicalcium ferrite and free calcium oxide. It can be found that the composition of steel slag is similar to that of Portland cement clinker. It is a cement-like material with potential gelling activity. In addition, steel slag is also a material with excellent physical properties. The steel slag aggregate has high angularity and rough surface texture. The shape of the particles provides high internal friction and can improve the bonding performance with the binder. In the steel industry, semi-dry and dry desulfurization technologies are widely used. According to statistics, nearly 150 sintering and pelletizing lines in my country use semi-dry desulfurization technology. Desulfurization ash will become the third largest solid waste in the steel industry after blast furnace slag and steel slag.

[0004] Rice husk ash is mainly produced in the direct combustion process of agricultural waste rice husk and biomass power plant boilers. It has the characteristics of rich pores, low specific gravity and large specific surface area. If it is not handled properly, it will cause serious dust, air and river pollution. Therefore, it is of great significance to conduct in-depth research on more low-carbon and economical ways to rationally utilize rice husk ash as a resource. Rice husk ash burned under certain conditions contains a large amount of SiO2, and the morphology of SiO2 is composed of nano-scale amorphous particles, which makes rice husk ash have properties similar to silica fume, which means that rice husk ash has potential gelling activity under certain conditions and can promote the formation of gelling hydration products such as CSH and CASH.

[0005] In recent years, my country has also made great progress in the comprehensive utilization of solid waste. However, due to the late start of research in this area and the low comprehensive utilization rate, my country has been in a state of high output, low consumption and high pollution. The physical composition of some solid wastes has the potential to prepare cementitious materials, but the effect is not good when used alone. For example, steel slag itself has problems such as low early activity and slow hydration rate. Therefore, in some environments or objective conditions, the use of solid waste for soil solidification has certain limitations. Summary of the invention

[0006] The purpose of the embodiment of the present application is to overcome at least one of the above technical deficiencies, and to propose a composite soil solidifier based on solid waste and a road use method thereof, which uses a composite soil solidifier with steel slag, desulfurization ash and rice husk ash as main raw materials for road construction, and utilizes the synergistic effect between the components to solidify the soil. In addition, polypropylene plastic waste is added on this basis to improve the solidification effect, so as to achieve the purpose of treating waste with waste and turning waste into treasure, and can effectively solidify special soil with poor engineering performance, with significant economic, social and environmental effects.

[0007] In order to achieve the above technical purpose, the embodiment of the present application provides a composite soil solidifier based on solid waste, which is composed of a powder component, a liquid component and a fiber reinforcement, wherein:

[0008] The powder component is prepared by weight from 45-55 parts of steel slag, 10-25 parts of desulfurization ash, 15-20 parts of rice husk ash and 10-15 parts of gypsum;

[0009] The liquid component is prepared by weight from 50 parts of water, 10-15 parts of sodium sulfate, 10-15 parts of sodium hydroxide and 20-25 parts of water glass;

[0010] The fiber reinforcement is polypropylene plastic.

[0011] Optionally, the steel slag is steel slag particles obtained after screening, crushing and magnetic separation to remove iron, the main component of which is CaO with a content of more than 50%, and passes through a 2 mm sieve.

[0012] Optionally, the desulfurized ash mainly consists of Al2O3 and CaO, the total content of which is above 50%, and after drying, it is ground by a grinder and passed through a 0.075 mm sieve.

[0013] Optionally, the rice husk ash is biomass solid waste produced under low-temperature combustion conditions of 550-650° C., has a silicon dioxide content of more than 80%, is dried and ground with a grinder, and passed through a 0.075 mm sieve.

[0014] The present application also provides a method for using the composite soil solidifying agent based on solid waste on a road, comprising:

[0015] Step 1: Construction preparation: level the subgrade layer of the roadbed, remove vegetation on the soil surface, and the soil surface removal range is slightly larger than the filling range. Sample the materials to be used as embankment filling materials to test the natural dry density and natural water content of the soil at the sampling point;

[0016] Step 2: Filling, spreading and leveling. The soil is transported to the paving site and piled on the roadbed from far to near according to the calculated spacing. The moisture content is controlled to be slightly higher than the optimal moisture content. After the filler meets the rolling requirements, it is first roughly leveled with a bulldozer, and then finely leveled with a grader according to the paving line to keep the filler paved flat and even.

[0017] Step 3: Add the curing agent. After the soil is leveled and statically pressed, artificial grids are laid according to the amount of powder components in the composite soil curing agent calculated in advance. The powder components in the composite soil curing agent are added according to the amount per grid, and then the liquid components in the composite soil curing agent are evenly sprayed according to a certain ratio. After spraying, water is added to the optimal moisture content of 50%;

[0018] Step 4: Mixing: Mix the powder part and the liquid part to obtain a water-soil mixture;

[0019] Step 5: Add waste plastics, cut the plastics into individual discrete fibers with a length of 20mm-30mm and a width of 2mm-3mm, distribute them as evenly as possible in the water-soil mixture according to a certain amount, and add the remaining water to the optimal moisture content to obtain a mixture;

[0020] Step 6: Mixing and leveling: Use a mixing machine to stir the paved mixture twice, and then stir it to the bottom after two times, and enter the lower layer 0.5-1cm. After the mixture meets the rolling requirements, leveling construction is carried out, and the loose paving thickness of the mixture is controlled at the same time;

[0021] Step 7: Rolling. During rolling construction, static pressure is used for the first pass, followed by vibration pressure, and the last pass is static pressure.

[0022] Optionally, in step one, the test items of the sampling test should include natural dry density, natural moisture content, liquid limit, plastic limit, particle analysis, compaction test and CBR test; the detection methods of soil at the sampling point include nuclear density meter method or ring knife method. When the planned sampling depth is large, the soil should be tested in layers and the average value should be taken.

[0023] Optionally, in step 2, before paving construction, the following steps may be further included:

[0024] In the evening of the day before filling, sprinkle water on the lower supporting layer of the planned soil pile. The watering should be even and not too wet to cause mud. To ensure uniform fill thickness, the soil should be filled strictly according to the size of the grid. The construction site should be directed by a dedicated person to unload the materials at the designated location.

[0025] Optionally, in step four, the mixing methods include factory mixing and road mixing. The factory mixing method is used for roadbed filling of high-grade highways and roadbed filling with a large scale of resource utilization; the road mixing method is used for roadbed filling of low-grade highways and roadbed filling with a small scale of resource utilization.

[0026] Optionally, in step seven, during the rolling process, if there is "spring", looseness or "peeling", it should be turned over and re-mixed in time, or treated with other rolling methods to meet the rolling requirements; the rolling construction shall be carried out until the top surface of the fill layer is stable, there is no sinking, the surface is flat and there are no wheel marks, and the corresponding rolling method and number of rolling times shall be recorded; if the rolled layer does not meet the quality requirements, the rolling process shall be modified in time. After the rolling construction is completed, the surface shall be flat and have the road humps required by the specifications.

[0027] Optionally, after step seven, the method further includes step eight: quality inspection.

[0028] The advantages of this application are:

[0029] 1. The powder component of the composite soil solidifier is made of steel slag, desulfurization ash and rice husk ash, which turns solid waste into treasure and realizes the recycling of two industrial solid wastes, steel slag and desulfurization ash, and one biological solid waste, rice husk ash. It is low-cost and can replace or partially replace cement, reduce production energy consumption and CO2 emissions, and has significant economic and environmental benefits. It is in line with my country's industrial policies of energy conservation, emission reduction, green and sustainable development, and has broad and far-reaching significance for the resource utilization of solid waste and the realization of dual carbon goals;

[0030] 2. The cementitious hydration products generated by the composite soil solidifier fill the soil particles, making the soil structure more stable and dense. The formation of cementing materials and aggregate structures reduces the internal pore structure of the soil and helps to strengthen the connection between particles, making the soil more stable and dense, thus having better mechanical properties;

[0031] 3. Using polypropylene plastic waste as fiber reinforcement material can better connect the soil structure, further play a bridging role, improve the "brittleness" of powder-cured soil, increase the toughness of the cured soil, and improve the elastic modulus of the overall soil structure;

[0032] 4. The powder component in the composite soil solidifier has a small particle size, which can improve its overall chemical activity, but it may cause slight shrinkage of the solidified soil volume after the reaction. The added polypropylene plastic waste and gypsum not only help to form strength, but also use their characteristics to maintain the stability of the entire solidification system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a road use method of a composite soil solidifying agent based on solid waste provided in an embodiment of the present application;

[0034] Figure 2 This is a diagram of the soil particle size distribution used in the examples of this application. DETAILED DESCRIPTION

[0035] This embodiment clearly and completely describes a road-use method of a high-efficiency composite solid waste sludge solidification technology and a composite soil solidifier based on solid waste in conjunction with a soft soil foundation treatment project of a ring expressway in a soft soil area. Obviously, the described embodiment is a part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] The embodiment of the present application provides a composite soil solidifier based on solid waste, which is composed of a powder component, a liquid component and a fiber reinforcement, wherein:

[0037] The powder component is prepared by weight from 45-55 parts of steel slag, 10-25 parts of desulfurization ash, 15-20 parts of rice husk ash and 10-15 parts of gypsum.

[0038] Specifically, the steel slag is steel slag particles obtained after screening, crushing, and magnetic separation to remove iron, and the main component is CaO, the content of which is more than 50%, and it can pass a 2mm sieve. The main components of the desulfurized ash are Al2O3 and CaO, and the total content of the two is more than 50%. After drying, it is ground with a grinder and passed through a 0.075mm sieve. The rice husk ash uses biomass solid waste produced under low-temperature combustion conditions of 550-650℃, with a silicon dioxide content of more than 80%. After drying, it is ground with a grinder and passed through a 0.075mm sieve.

[0039] The liquid component is prepared by weight from 50 parts of water, 10-15 parts of sodium sulfate, 10-15 parts of sodium hydroxide and 20-25 parts of water glass;

[0040] The fiber reinforcement is polypropylene plastic, and plastic bag garbage can be used. The plastic bag garbage is required to be decomposed and cut into single discrete fibers with a length of 20mm-30mm and a width of 2mm-3mm.

[0041] The chemical compositions of the steel slag, desulfurization ash and rice husk ash used in this application are shown in Table 1.

[0042] Table 1 Chemical composition of steel slag, desulfurization ash and rice husk ash

[0043]

[0044] The steel slag and desulfurization ash used in this application come from Xinyu Metallurgical Materials Factory in China. The steel slag and desulfurization ash are dried in a constant temperature drying oven to constant weight, and then the steel slag is ground to less than 2 mm using a ball mill. The average particle size of the desulfurization ash is 3.8 μm, and no grinding is required.

[0045] The rice husk ash used in the present application is a black powder. The rice husk ash is dried in a constant temperature drying oven to a constant weight, and then ground into powder less than 0.075 mm using a ball mill. The average particle size of the processed rice husk ash is 9.46 μm.

[0046] In this application, polypropylene plastic waste is used as fiber reinforcement material, and plastic bag garbage is used. The plastic bag garbage is decomposed and cut into single discrete fibers with a length of 20mm-30mm and a width of 2mm-2.5mm, and placed for standby use.

[0047] The solid water glass used in the present application has a modulus of 1.6 and a Baume degree of 40; the Na2SO4 used is in powder form with a purity of ≥98%; and the NaOH used is in powder form with a purity of ≥96%.

[0048] See also Figure 1 As shown, the embodiment of the present application also provides a road use method of the composite soil solidifying agent based on solid waste, comprising:

[0049] Step 1: Construction preparation: level the subgrade layer of the roadbed, remove vegetation on the soil surface, and the soil surface removal range is slightly larger than the filling range. Sample the materials to be used as embankment filling materials to test the natural dry density and natural water content of the soil at the sampling point;

[0050] Specifically, before actual construction, workers need to level the underlying layer of the roadbed and remove the tree roots and other vegetation on the soil surface. The surface is leveled with a grader or bulldozer to make it smooth, and the clearing range is slightly larger than the filling range. The flatness of the roadbed surface can ensure that the relevant indicators of the underlying layer are in line with the requirements of the corresponding specifications.

[0051] The materials to be used as embankment fillers should be sampled and tested in time. Soil test items should include natural dry density, natural moisture content, liquid limit, plastic limit, particle analysis, compaction test, CBR test, etc. Detect the natural dry density and natural moisture content of the soil at the sampling point. The nuclear density meter method or the ring knife method can be used. When the scheduled sampling depth is large, it should be tested in layers and the average value should be taken.

[0052] The loose thickness of the filler is determined based on the conditions of the construction machinery and the results of the test section. The unloading area of ​​each truck is determined based on the loading capacity and loose thickness of the dump truck to facilitate paving and leveling, and a grid is drawn with white lime.

[0053] The soil used in this application was collected from a highway site near Xinyu City, Jiangxi Province, China, with a depth of more than 2 meters. The physical properties of the soil sample are shown in Table 2, and the particle size distribution is as follows: Figure 2 The soil is classified as high plastic clay (CH), which has a high natural water content, a high liquid limit, a large plasticity index, and a high strength under dry conditions. Once it comes into contact with water, it will soften rapidly, the linear expansion rate will rise sharply, the strength will drop sharply, and the water stability is extremely poor.

[0054] Table 2 Soil properties

[0055] parameter value proportion 2.53 Natural moisture content (%) 28.5 Liquid limit (%) 65.0 Plastic limit (%) 31.4 Plasticity index (%) 33.5 <![CDATA[Maximum dry density (g / cm 3 )]]> 1.71 Optimum moisture content (%) 22.0 California load factor (%) 7.28 Unconfined compressive strength (MPa) 0.79

[0056] Step 2: Filling, spreading and leveling. The soil is transported to the paving site and piled on the roadbed from far to near according to the calculated spacing. The moisture content is controlled to be slightly higher than the optimal moisture content. After the filler meets the rolling requirements, it is first roughly leveled with a bulldozer, and then finely leveled with a grader according to the paving line to keep the filler paved flat and even.

[0057] Specifically, the soil from the soil storage plant is transported to the paving site by a dump truck, and the soil is piled on the roadbed from far to near according to the calculated spacing, and its water content is controlled to be slightly greater than the optimal water content. In the evening of the day before the soil is added, water is sprinkled on the lower bearing layer of the scheduled soil pile. The watering should be uniform and should not be too wet to cause mud. In order to ensure the uniform thickness of the fill, the soil should be added strictly according to the size of the cloth grid, and the construction site should be directed by a special person to unload the material at the designated location. During the paving construction, the loose paving thickness should be controlled and tested to ensure that the paving thickness is uniform and consistent, meeting the requirements determined by the test section. After the filler meets the rolling requirements, it is first roughly leveled with a bulldozer, and then the grader is finely leveled according to the paving line. At the same time, 3 to 5 people and a wheelbarrow are equipped behind the bulldozer to fill the gaps or remove the blocks that do not meet the requirements, so that the filler paving remains flat and uniform. During the paving period, attention should be paid to the flatness and uniformity of the edge of the embankment.

[0058] Step 3: Add the curing agent. After the soil is leveled and statically pressed, artificial grids are laid according to the amount of powder components in the composite soil curing agent calculated in advance. The powder components in the composite soil curing agent are added according to the amount per grid, and then the liquid components in the composite soil curing agent are evenly sprayed according to a certain ratio. After spraying, water is added to the optimal moisture content of 50%;

[0059] Step 4: Mixing: Mix the powder part and the liquid part to obtain a water-soil mixture;

[0060] Specifically, there are two mixing methods: factory mixing and road mixing. The factory mixing method is used for high-grade highways and roadbed filling with large-scale resource utilization, and its mixing quality is good; the road mixing method is used for low-grade highways and roadbed filling with small-scale resource utilization. In addition, the road mixing method construction technology has obvious construction advantages over other construction technologies during road construction, such as simple and convenient construction and low investment cost.

[0061] Step 5: Add waste plastics, cut the plastics into individual discrete fibers with a length of 20mm-30mm and a width of 2mm-3mm, distribute them as evenly as possible in the water-soil mixture according to a certain amount, and add the remaining water to the optimal moisture content to obtain a mixture;

[0062] Step 6: Mixing and leveling: Use a mixing machine to stir the paved mixture twice, and then stir it to the bottom after two times, and enter the lower layer 0.5-1cm. After the mixture meets the rolling requirements, leveling construction is carried out, and the loose paving thickness of the mixture is controlled at the same time;

[0063] Specifically, first use a mixing machine to stir the paved mixture twice, but do not stir it to the bottom to prevent the curing agent and fiber reinforcement material from falling to the bottom. The last two times should be stirred to the bottom and preferably enter the lower layer 0.5 to 1 cm, so that the curing agent and fiber reinforcement material are evenly distributed in the fill, and at the same time facilitate the bonding of the upper and lower layers. It is strictly forbidden to leave "fill" between the upper and lower layers. At the same time, it is necessary to prevent the mixture from being stirred too deeply or too much, which will damage the surface structure of the lower layer. After mixing evenly, the mixture should have a consistent color. After the mixture meets the rolling requirements, leveling construction can be carried out. During leveling, the loose paving thickness of the mixture should be controlled at any time.

[0064] Step 7: Rolling. During rolling construction, static pressure is used for the first time, followed by vibration pressure, and static pressure is used for the last time.

[0065] Specifically, the rolling work adopts the layered rolling method, and a roller of more than 18 tons should be selected. The rolling should be a combination of static pressure and vibration pressure. The best rolling technology used in the construction process is applicable after field testing. During the rolling construction, static pressure should be used for the first pass, followed by vibration and other rolling methods, and static pressure should be used for the last pass. The specific rolling technology and number of rolling passes should be determined according to the test section. During the rolling process, if there are "spring", looseness, "peeling" and other phenomena, they should be turned over and re-mixed in time, or other rolling methods should be used to treat them to meet the rolling requirements. Rolling construction is carried out until the top surface of the filling layer is stable, there is no sinking, the surface is flat and there is no wheel mark, and the corresponding rolling method and number of rolling passes are recorded. If the rolling layer does not meet the quality requirements such as compaction, the rolling technology should be modified in time. After the rolling construction is completed, the surface should be flat and have the road humps required by the specifications.

[0066] Step 8: Quality inspection.

[0067] The solid waste-based composite soil solidifier provided in the present application is described in detail below with reference to specific Examples 1-8 and comparative examples.

[0068] Example 1

[0069] The composite soil solidifier in this embodiment 1 includes powder, fiber reinforcement and liquid, wherein the powder component is prepared from 47 parts of steel slag, 23 parts of desulfurization ash, 18 parts of rice husk ash and 12 parts of gypsum; the liquid component is prepared from 50 parts of water, 13 parts of sodium sulfate, 12 parts of sodium hydroxide and 25 parts of water glass.

[0070] This embodiment requires that desulfurized ash, rice husk ash and gypsum be ground and dried in a constant temperature drying oven to constant weight and then crushed to less than 0.075 mm; steel slag is required to be dried in a constant temperature drying oven to constant weight and then crushed to less than 2 mm. The powders are mixed and stirred evenly in a mixer for later use.

[0071] This embodiment requires adding 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass to 50 parts of water at room temperature, stirring until the solid is completely dissolved to obtain a transparent liquid component for use.

[0072] In this embodiment, polypropylene plastic waste is used as fiber reinforcement material, and plastic bag waste is used. The quality of the fiber is checked by hand tension. If the fiber is easy to break, it is not used. The plastic bag waste is decomposed and cut into single discrete fibers with a length of 20mm-40mm and a width of 2mm-3mm, and placed for use.

[0073] In this embodiment, the powder is added to the soil at a dosage of 18% (i.e., the powder product accounts for 18% of the total mass), and after being fully stirred, the liquid component is evenly sprayed at a dosage of 5% (i.e., the liquid component accounts for 18% of the total mass). After spraying, water is added to 50% of the optimal moisture content, and then the fiber reinforcement material is distributed as evenly as possible in the hydrated soil mixture at 0.4% of the total mass, and the remaining water is added to the optimal moisture content, stirred evenly, and a solidified soil specimen is prepared. It is worth noting that since the fibers tend to aggregate together, it is necessary to be as careful as possible to ensure that the fiber reinforcement material is evenly distributed in the mixture.

[0074] Example 2

[0075] The composite soil solidifying agent in this embodiment 2 includes powder, fiber reinforcement and liquid, wherein the powder component is prepared by 47 parts of steel slag, 17 parts of desulfurized ash, 24 parts of rice husk ash and 12 parts of gypsum; the liquid component is prepared by 50 parts of water, 13 parts of sodium sulfate, 14 parts of sodium hydroxide and 23 parts of water glass. The other preparation and steps are the same as those in embodiment 1, and will not be repeated.

[0076] Example 3

[0077] The composite soil solidifying agent in this embodiment 3 includes powder, fiber reinforcement and liquid, wherein the powder component is prepared by 47 parts of steel slag, 11 parts of desulfurized ash, 30 parts of rice husk ash and 12 parts of gypsum; the liquid component is prepared by 50 parts of water, 13 parts of sodium sulfate, 16 parts of sodium hydroxide and 21 parts of water glass. The other preparation and steps are the same as those in embodiment 1, and will not be repeated.

[0078] Example 4

[0079] The composite soil solidifier in this embodiment 4 includes powder, fiber reinforcement and liquid, wherein the powder component is prepared from 53 parts of steel slag, 17 parts of desulfurization ash, 18 parts of rice husk ash, and 12 parts of gypsum; the liquid component is prepared from 50 parts of water, 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass.

[0080] This embodiment requires that desulfurized ash, rice husk ash and gypsum be ground and dried in a constant temperature drying oven to constant weight and then crushed to less than 0.075 mm; steel slag is required to be dried in a constant temperature drying oven to constant weight and then crushed to less than 2 mm. The powders are mixed and stirred evenly in a mixer for later use.

[0081] This embodiment requires adding 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass to 50 parts of water at room temperature, stirring until the solid is completely dissolved to obtain a transparent liquid component for use.

[0082] In this embodiment, polypropylene plastic waste is used as fiber reinforcement material, and plastic bag waste is used. The quality of the fiber is checked by hand tension. If the fiber is easy to break, it is not used. The plastic bag waste is decomposed and cut into single discrete fibers with a length of 20mm-40mm and a width of 2mm-3mm, and placed for use.

[0083] In this embodiment, the powder is added to the soil at a dosage of 18% (i.e., the powder product accounts for 18% of the total mass), and after being fully stirred, the liquid component is evenly sprayed at a dosage of 6% (i.e., the liquid component accounts for 18% of the total mass). After spraying, water is added to 50% of the optimal moisture content, and then the fiber reinforcement material is distributed as evenly as possible in the hydrated soil mixture at 0.4% of the total mass, and the remaining water is added to the optimal moisture content, stirred evenly, and a solidified soil specimen is prepared. It is worth noting that since the fibers tend to aggregate together, it is necessary to be as careful as possible to ensure that the fiber reinforcement material is evenly distributed in the mixture.

[0084] Example 5

[0085] The composite soil solidifier in this embodiment 5 includes powder, fiber reinforcement and liquid, wherein the powder component is prepared from 53 parts of steel slag, 13 parts of desulfurization ash, 24 parts of rice husk ash and 10 parts of gypsum; the liquid component is prepared from 50 parts of water, 13 parts of sodium sulfate, 12 parts of sodium hydroxide and 25 parts of water glass.

[0086] This embodiment requires that desulfurized ash, rice husk ash and gypsum be ground and dried in a constant temperature drying oven to constant weight and then crushed to less than 0.075 mm; steel slag is required to be dried in a constant temperature drying oven to constant weight and then crushed to less than 2 mm. The powders are mixed and stirred evenly in a mixer for later use.

[0087] This embodiment requires adding 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass to 50 parts of water at room temperature, stirring until the solid is completely dissolved to obtain a transparent liquid component for use.

[0088] In this embodiment, polypropylene plastic waste is used as fiber reinforcement material, and plastic bag waste is used. The quality of the fiber is checked by hand tension. If the fiber is easy to break, it is not used. The plastic bag waste is decomposed and cut into single discrete fibers with a length of 20mm-40mm and a width of 2mm-3mm, and placed for use.

[0089] In this embodiment, the powder is added to the soil at a dosage of 21% (i.e., the powder product accounts for 18% of the total mass), and after being fully stirred, the liquid component is evenly sprayed at a dosage of 7% (i.e., the liquid component accounts for 18% of the total mass). After spraying, water is added to 50% of the optimal moisture content, and then the fiber reinforcement material is distributed as evenly as possible in the hydrated soil mixture at 0.4% of the total mass, and the remaining water is added to the optimal moisture content, stirred evenly, and a solidified soil specimen is prepared. It is worth noting that since the fibers tend to aggregate together, it is necessary to be as careful as possible to ensure that the fiber reinforcement material is evenly distributed in the mixture.

[0090] Example 6

[0091] The composite soil solidifier in this embodiment 6 includes powder, fiber reinforcement and liquid, wherein the powder component is prepared from 47 parts of steel slag, 23 parts of desulfurization ash, 18 parts of rice husk ash, and 12 parts of gypsum; the liquid component is prepared from 50 parts of water, 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass.

[0092] This embodiment requires that desulfurized ash, rice husk ash and gypsum be ground and dried in a constant temperature drying oven to constant weight and then crushed to less than 0.075 mm; steel slag is required to be dried in a constant temperature drying oven to constant weight and then crushed to less than 2 mm. The powders are mixed and stirred evenly in a mixer for later use.

[0093] This embodiment requires adding 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass to 50 parts of water at room temperature, stirring until the solid is completely dissolved to obtain a transparent liquid component for use.

[0094] In this embodiment, polypropylene plastic waste is used as fiber reinforcement material, and plastic bag waste is used. The quality of the fiber is checked by hand tension. If the fiber is easy to break, it is not used. The plastic bag waste is decomposed and cut into single discrete fibers with a length of 20mm-40mm and a width of 2mm-3mm, and placed for use.

[0095] In this embodiment, the powder is added to the soil at a dosage of 18% (i.e., the powder product accounts for 18% of the total mass), and after being fully stirred, the liquid component is evenly sprayed at a dosage of 5% (i.e., the liquid component accounts for 18% of the total mass). After spraying, water is added to 50% of the optimal moisture content, and then the fiber reinforcement material is distributed as evenly as possible in the hydrated soil mixture at 0.8% of the total mass, and the remaining water is added to the optimal moisture content, stirred evenly, and a solidified soil specimen is prepared. It is worth noting that since the fibers tend to aggregate together, it is necessary to be as careful as possible to ensure that the fiber reinforcement material is evenly distributed in the mixture.

[0096] Example 7

[0097] The composite soil solidifier in this embodiment 7 includes powder, fiber reinforcement and liquid, wherein the powder component is prepared from 47 parts of steel slag, 23 parts of desulfurization ash, 18 parts of rice husk ash, and 12 parts of gypsum; the liquid component is prepared from 50 parts of water, 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass.

[0098] This embodiment requires that desulfurized ash, rice husk ash and gypsum be ground and dried in a constant temperature drying oven to constant weight and then crushed to less than 0.075 mm; steel slag is required to be dried in a constant temperature drying oven to constant weight and then crushed to less than 2 mm. The powders are mixed and stirred evenly in a mixer for later use.

[0099] This embodiment requires adding 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass to 50 parts of water at room temperature, stirring until the solid is completely dissolved to obtain a transparent liquid component for use.

[0100] In this embodiment, polypropylene plastic waste is used as fiber reinforcement material, and plastic bag waste is used. The quality of the fiber is checked by hand tension. If the fiber is easy to break, it is not used. The plastic bag waste is decomposed and cut into single discrete fibers with a length of 20mm-40mm and a width of 2mm-3mm, and placed for use.

[0101] In this embodiment, the powder is added to the soil at a dosage of 24% (i.e., the powder product accounts for 18% of the total mass), and after being fully stirred, the liquid component is evenly sprayed at a dosage of 7% (i.e., the liquid component accounts for 18% of the total mass). After spraying, water is added to 50% of the optimal moisture content, and then the fiber reinforcement material is distributed as evenly as possible in the hydrated soil mixture at 0.8% of the total mass, and the remaining water is added to the optimal moisture content, stirred evenly, and a solidified soil specimen is prepared. It is worth noting that since the fibers tend to aggregate together, it is necessary to be as careful as possible to ensure that the fiber reinforcement material is evenly distributed in the mixture.

[0102] Example 8

[0103] The composite soil solidifier in this Example 8 includes powder, fiber reinforcement and liquid, wherein the powder component is prepared from 47 parts of steel slag, 23 parts of desulfurization ash, 18 parts of rice husk ash, and 12 parts of gypsum; the liquid component is prepared from 50 parts of water, 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass.

[0104] This embodiment requires that desulfurized ash, rice husk ash and gypsum be ground and dried in a constant temperature drying oven to constant weight and then crushed to less than 0.075 mm; steel slag is required to be dried in a constant temperature drying oven to constant weight and then crushed to less than 2 mm. The powders are mixed and stirred evenly in a mixer for later use.

[0105] This embodiment requires adding 13 parts of sodium sulfate, 12 parts of sodium hydroxide, and 25 parts of water glass to 50 parts of water at room temperature, stirring until the solid is completely dissolved to obtain a transparent liquid component for use.

[0106] In this embodiment, polypropylene plastic waste is used as fiber reinforcement material, and plastic bag waste is used. The quality of the fiber is checked by hand tension. If the fiber is easy to break, it is not used. The plastic bag waste is decomposed and cut into single discrete fibers with a length of 20mm-40mm and a width of 2mm-3mm, and placed for use.

[0107] In this embodiment, the powder is added to the soil at a dosage of 30% (i.e., the powder product accounts for 18% of the total mass), and after being fully stirred, the liquid component is evenly sprayed at a dosage of 9% (i.e., the liquid component accounts for 18% of the total mass). After spraying, water is added to 50% of the optimal moisture content, and then the fiber reinforcement material is distributed as evenly as possible in the hydrated soil mixture at 0.8% of the total mass, and the remaining water is added to the optimal moisture content, stirred evenly, and a solidified soil specimen is prepared. It is worth noting that since the fibers tend to aggregate together, it is necessary to be as careful as possible to ensure that the fiber reinforcement material is evenly distributed in the mixture.

[0108] Comparative Example

[0109] In this comparative example, P.O42.5R cement is used as a soil solidifier, which is added into the soil at 6% of the total mass. After the soil is stirred evenly, water is added to the soil to reach the optimum moisture content, and the soil is stirred evenly to prepare a solidified soil specimen.

[0110] After the specimens were prepared according to the above case, they were immediately wrapped in plastic wrap and then transferred to a standard curing box for curing. After the required number of curing days, the performance parameters of each cured soil specimen were tested. The results are shown in Table 3 below.

[0111] Table 3 Test results

[0112]

[0113] It can be seen from the test results in Table 3 that the CBR value, 7d unconfined compressive strength and water stability of the cured soil specimens of Examples 1-8 of the present application are in compliance with JTG D50-2017 "Highway Asphalt Pavement Design Specification" and JTGD 30-2015 "Highway Roadbed Design Specification", indicating that the composite soil curing agent provided in the present application has a better curing effect and can replace or partially replace cement for soil curing in highway engineering.

[0114] The advantages of this application are:

[0115] 1. The powder component of the composite soil solidifier is made of steel slag, desulfurization ash and rice husk ash, which turns solid waste into treasure and realizes the recycling of two industrial solid wastes, steel slag and desulfurization ash, and one biological solid waste, rice husk ash. It is low-cost and can replace or partially replace cement, reduce production energy consumption and CO2 emissions, and has significant economic and environmental benefits. It is in line with my country's industrial policy of energy conservation, emission reduction, green and sustainable development, and has broad and far-reaching significance for the resource utilization of solid waste;

[0116] 2. The cementitious hydration products generated by the composite soil solidifier fill the soil particles, making the soil structure more stable and dense. The formation of cementing materials and aggregate structures reduces the internal pore structure of the soil and helps to strengthen the connection between particles, making the soil more stable and dense, thus having better mechanical properties;

[0117] 3. Using polypropylene plastic waste as fiber reinforcement material can better connect the soil structure, further play a bridging role, improve the "brittleness" of powder-cured soil, increase the toughness of the cured soil, and improve the elastic modulus of the overall soil structure;

[0118] 4. The powder component in the composite soil solidifier has a small particle size, which can improve its overall chemical activity, but it may cause slight shrinkage of the solidified soil volume after the reaction. The added polypropylene plastic waste and gypsum not only help to form strength, but also use their characteristics to maintain the stability of the entire solidification system.

[0119] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A composite soil solidifier based on solid waste, characterized in that: It is composed of a powder component, a liquid component and a fiber reinforcement, wherein: The powder component is prepared by weight from 45-55 parts of steel slag, 10-25 parts of desulfurization ash, 15-20 parts of rice husk ash and 10-15 parts of gypsum; The liquid component is prepared by weight from 50 parts of water, 10-15 parts of sodium sulfate, 10-15 parts of sodium hydroxide and 20-25 parts of water glass; The fiber reinforcement is polypropylene plastic.

2. The composite soil solidifier based on solid waste according to claim 1, characterized in that: The steel slag is steel slag particles obtained after screening, crushing and magnetic separation to remove iron, and the main component is CaO, the content of which is more than 50%, and passes through a 2mm sieve.

3. The composite soil solidifier based on solid waste according to claim 1, characterized in that: The desulfurized ash is mainly composed of Al2O3 and CaO, the total content of which is above 50%. After drying, it is ground by a grinder and passed through a 0.075mm sieve.

4. The composite soil solidifier based on solid waste according to claim 1, characterized in that: The rice husk ash is biomass solid waste produced under low-temperature combustion conditions of 550-650° C., has a silicon dioxide content of more than 80%, is ground by a grinder after drying, and passes through a 0.075 mm sieve.

5. A method for road use of the composite soil solidifier based on solid waste according to any one of claims 1 to 4, characterized in that: include: Step 1: Construction preparation: level the subgrade layer of the roadbed, remove vegetation on the soil surface, and the soil surface removal range is slightly larger than the filling range. Sample the materials to be used as embankment filling materials to test the natural dry density and natural water content of the soil at the sampling point; Step 2: Filling, spreading and leveling. The soil is transported to the paving site and piled on the roadbed from far to near according to the calculated spacing. The moisture content is controlled to be slightly higher than the optimal moisture content. After the filler meets the rolling requirements, it is first roughly leveled with a bulldozer, and then finely leveled with a grader according to the paving line to keep the filler paved flat and even. Step 3: Add the curing agent. After the soil is leveled and statically pressed, artificial grids are laid according to the amount of powder components in the composite soil curing agent calculated in advance. The powder components in the composite soil curing agent are added according to the amount per grid, and then the liquid components in the composite soil curing agent are evenly sprayed according to a certain ratio. After spraying, water is added to the optimal moisture content of 50%; Step 4: Mixing: Mix the powder part and the liquid part to obtain a water-soil mixture; Step 5: Add waste plastics, cut the plastics into individual discrete fibers with a length of 20mm-30mm and a width of 2mm-3mm, distribute them as evenly as possible in the water-soil mixture according to a certain amount, and add the remaining water to the optimal moisture content to obtain a mixture; Step 6: Mixing and leveling: Use a mixing machine to stir the paved mixture twice, and then stir it to the bottom after two times, and enter the lower layer 0.5-1cm. After the mixture meets the rolling requirements, leveling construction is carried out, and the loose paving thickness of the mixture is controlled at the same time; Step 7: Rolling. During rolling construction, static pressure is used for the first pass, followed by vibration pressure, and the last pass is static pressure.

6. The method according to claim 5, characterized in that In step one, the test items of the sampling test should include natural dry density, natural moisture content, liquid limit, plastic limit, particle analysis, compaction test and CBR test; the detection methods of soil at the sampling point include nuclear density meter method or ring knife method. When the planned sampling depth is large, the soil should be tested in layers and the average value should be taken.

7. The method according to claim 6, characterized in that In step 2, before paving construction, it also includes: In the evening of the day before filling, sprinkle water on the lower supporting layer of the planned soil pile. The watering should be even and not too wet to cause mud. To ensure uniform fill thickness, the soil should be filled strictly according to the size of the grid. The construction site should be directed by a dedicated person to unload the materials at the designated location.

8. The method according to claim 5, characterized in that In step four, the mixing methods include factory mixing and road mixing. The factory mixing method is used for roadbed filling on high-grade highways and roadbeds with a large scale of resource utilization; the road mixing method is used for roadbed filling on low-grade highways and roadbeds with a small scale of resource utilization.

9. The method according to claim 5, characterized in that In step seven, during the rolling process, if there is any "spring", looseness or "peeling" phenomenon, it should be turned over and re-mixed in time, or treated with other rolling methods to meet the rolling requirements; the rolling construction should be carried out until the top surface of the fill layer is stable, there is no sinking, the surface is flat and there are no wheel marks, and the corresponding rolling method and number of rolling times are recorded; if the rolled layer does not meet the quality requirements, the rolling process should be modified in time. After the rolling construction is completed, the surface should be flat and have the road humps required by the specifications.

10. The method according to claim 5, characterized in that After step seven, step eight is also included: quality inspection.

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