A quick-hardening and early-strength soft soil stabilizer based on ammonia alkali white mud and a preparation method thereof

Abstract

The present application relates to a kind of soft soil solidifying agent based on ammonia alkali white mud and its preparation method, the present application is according to the weight ratio of ammonia alkali white mud 10~40%, mineral powder 30~60%, steel slag powder 0~30%, desulfurization gypsum 5~20%, cement 0~15%, lime 0~10%, activator 0~3%.The present application can realize the fast hardening and early strength effect of soft soil solidification, 1d can reach 1.0MPa or more, shorten construction period, and cost is lower.

Description

Technical Field

[0001] The invention relates to the technical field of soft soil curing agents, in particular to a rapid-hardening and early-strengthening soft soil curing agent based on ammonia-alkali white mud and a preparation method thereof. Background Art

[0002] Soft soil solidifiers are inorganic hydraulic cementitious materials used to solidify soft soil and other fine-grained soils. Currently, commonly used soft soil solidifiers include cement, lime, and various industrial solid waste composite solidifiers. Cement and lime are relatively expensive, and due to their own characteristics, they are not effective in many soil solidification fields such as saline soil, soil with high organic matter content, and soil with high water content. The production process of cement and lime also requires the emission of large amounts of carbon dioxide. Currently, they are gradually being replaced by low-cost, high-performance industrial solid waste composite solidifiers. However, they generally have the problems of slow early reaction and low early strength. In order to obtain higher early strength, many studies have added alkali such as sodium hydroxide and water glass to stimulate industrial solid waste, or added early-strength cement such as sulfoaluminate cement or aluminate cement to provide early strength. The cost of obtaining early strength remains high, and the addition of alkali in the actual construction process has certain risks.

[0003] Ammonia-alkali white mud has the characteristics of high alkali, high chlorine, high sulfur and high fineness, which makes it difficult to use in the preparation of building materials. However, it has advantages in the preparation of soft soil solidifying agents, as it can play the role of chemical stimulation and physical filling.

[0004] In recent years, with breakthroughs in grinding technology, the building materials industry has achieved low-cost production of ultrafine powders. Higher early strength can be obtained through ultrafine mechanical activation, which is safer than chemical activation.

[0005] Authorization number CN 102153326B (A soft soil solidifying agent and its application), the soft soil solidifying agent includes 10-25% cement clinker, 65%-80% slag, 4-10% filling material, 1-10% expansion agent, 0.2-5% alkaline activator and 0.02-0.3% surfactant, wherein the filling material is fine sand and / or fly ash, the expansion agent is raw gypsum or desulfurized gypsum, the expansion agent is quicklime or sodium hydroxide; the surfactant is triethanolamine or calcium lignin sulfonate, and the dosage of the soft soil solidifying agent is 8%-20% of the weight of the reinforced soil.

[0006] Authorization number CN 102899048B (Desulfurized Gypsum Alkali Slag Soil Solidifier) ​​discloses a desulfurized gypsum alkali slag soil solidifier, characterized by being prepared from the following components in weight percentage: 12-30% desulfurized gypsum, 20-50% alkali slag, 0-30% slag, 0-5% admixture, and 0-20% fly ash; the desulfurized gypsum contains greater than 38% sulfur trioxide; the desulfurized gypsum is wet-discharge gypsum from flue gas desulfurization in power plants; the admixture is one or more of silicate, aluminate, and sulfoaluminate; and the alkali slag is ground to have a specific surface area greater than 450 m² / kg. Preparation method: First, grind the alkali slag with a specific surface area greater than 450 m² / kg with slag powder and fly ash for 15 minutes, then add the desulfurized gypsum and admixture and mechanically mix for 10 minutes to obtain the desulfurized gypsum alkali slag soil solidifier. This patent does not reflect the rapid hardening and early strength of the soft soil solidifier. When the incorporation ratio is 10%, the 28-day strength of the solidified soil is relatively low, only 0.75 to 1.05 MPa, and is not suitable for applications with high strength requirements.

[0007] Application Publication No. CN 117776649A (Preparation Method for a Rapid-Hardening Curing Agent Suitable for Soft Silt Soil) relates to the technical field of soft silt soil and discloses a preparation method for a rapid-hardening curing agent suitable for soft silt soil, comprising the following preparation steps: 1) preparing main ingredients, including fly ash, gypsum, aluminate cement, and mineral powder; preparing an activator, including quicklime, water glass, and sodium hydroxide; the ratio of the main ingredients to the activator being (9.5-11) to (0.8-1.2) by weight; 2) placing the main ingredients and the activator in a blender and stirring to form a mixture; placing the mixture and water in a blender and stirring to form a curing agent; the ratio of the mixture to the water being (0.9-1.3) to (0.8-1.2) by weight. The activator components in the curing agent are quicklime, water glass, and sodium hydroxide, which are relatively expensive and account for approximately 10%, resulting in high costs.

[0008] Currently, there are few patents and published literature that address fast-hardening, early-strengthening soft soil stabilizers. Most currently use cement, mineral powder, fly ash, and other cementing materials, with activators such as water glass, sodium hydroxide, and sodium sulfate used to activate these admixtures to achieve strength development. Furthermore, some patents incorporate expensive sulfoaluminate cement or aluminate cement to increase the setting and hardening speed, resulting in generally high costs for these soft soil stabilizers. Therefore, there is a need for a fast-hardening, early-strengthening soft soil stabilizer based on ammonia-soda white mud and a preparation method thereof. Summary of the Invention

[0009] The purpose of the present invention is to provide a rapid-hardening and early-strengthening soft soil solidifying agent based on ammonia-alkali white mud and a preparation method thereof.

[0010] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0011] In the first aspect, a fast-hardening and early-strengthening soft soil solidifier based on ammonia-alkali white mud is provided, which comprises, by weight, 10-40% ammonia-alkali white mud, 30-60% mineral powder, 0-30% steel slag powder, 5-20% desulfurized gypsum, 0-15% cement, 0-10% lime, and 0-3% activator.

[0012] Furthermore, the ammonia-soda mud is solid waste generated during the preparation of soda ash by the ammonia-soda process. After filtering, breaking up, airing and drying, the ammonia-soda mud with a moisture content of less than 5% is obtained, and the content of the ammonia-soda mud is greater than 99%.

[0013] Furthermore, the mineral powder is S95 grade granulated blast furnace slag powder with a specific surface area greater than 400m 2 / kg.

[0014] Furthermore, the steel slag powder is Grade II steel slag powder with a specific surface area greater than 350m 2 / kg.

[0015] Furthermore, the desulfurized gypsum has a dihydrate gypsum content greater than 90%, is dried to a moisture content less than 5%, and has a specific surface area of ​​200 to 400 m 2 / kg.

[0016] Furthermore, the cement is one or more mixtures of 42.5 grade Portland cement, composite Portland cement or slag Portland cement.

[0017] Furthermore, the lime is a mixture of calcium oxide, calcium hydroxide and calcium carbonate, which is obtained by drying and then passing through a 0.15mm sieve.

[0018] Furthermore, the activator is any one of aluminum sulfate and alum or a mixture of the two.

[0019] In the second aspect, the preparation method of the fast-hardening and early-strength soft soil curing agent based on ammonia-alkali white mud is as follows: ammonia-alkali white mud, mineral powder, steel slag powder, desulfurized gypsum, cement, lime, and activator are transported to an ultrafine ball mill for ultrafine grinding, and then the powder is sent to a powder separator for sorting to obtain a specific surface area of ​​more than 700m 2 / kg product is a fast-hardening and early-strengthening soft soil solidifier.

[0020] The beneficial effects of the present invention are:

[0021] The present invention is a fast-hardening and early-strengthening soft soil curing agent based on ammonia-alkali white mud and a preparation method thereof. Compared with the prior art, the present invention has the following technical effects:

[0022] The present invention has the following beneficial effects compared to the prior art:

[0023] The present invention can achieve the effect of rapid hardening and early strengthening of soft soil, reaching above 1.0 MPa in 1 day, thus shortening the construction period.

[0024] The present invention uses ammonia-soda white mud as a key raw material, and accounts for a high proportion of the soft soil solidifier, opening up a way for its large-scale utilization. Since industrial solid waste accounts for more than 90% of the soft soil solidifier, the cost is relatively low. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an electron microscope picture of the early-age hydration product of the solidified soil of the fast-hardening and early-strength soft soil solidifier based on ammonia-alkali white mud and its preparation method of the present invention. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] The present invention comprises the following steps:

[0028] A fast-hardening and early-strengthening soft soil solidifier based on ammonia-alkali white mud is composed of ammonia-alkali white mud, mineral powder, steel slag powder, desulfurized gypsum, cement, lime, and an activator. The proportions of the components are: 10-40% of ammonia-alkali white mud, 30-60% of mineral powder, 0-30% of steel slag powder, 5-20% of desulfurized gypsum, 0-15% of cement, 0-10% of lime, and 0-3% of activator.

[0029] Ammonia-soda mud itself is alkaline, which can stimulate the mineral powder to cause the depolymerization of silicon-oxygen bonds and aluminum-oxygen bonds. It also contains soluble chlorides and sulfates, which can produce ettringite and Friedel salts with mineral powder. At the same time, ammonia-soda mud is a nanoparticle, which can play a certain filling role after grinding and promote strength growth.

[0030] Mineral powder is the main body of the reaction, providing silicon-oxygen tetrahedrons and aluminum-oxygen tetrahedrons for the reaction system, and providing the basis for the formation of hydrated calcium silicate and ettringite.

[0031] Steel slag powder provides an alkaline environment for the reaction system. At the same time, the steel slag also generates a certain amount of calcium silicate hydrate gel. A small amount of aluminate in the steel slag will also react with desulfurization gypsum and chloride salt to generate ettringite and Friedel salt.

[0032] Desulfurized gypsum provides sulfate to the system and promotes the formation of ettringite.

[0033] On the one hand, cement hydration produces hydrated calcium silicate and calcium hydroxide, which provide a source of strength and an alkaline environment.

[0034] Lime provides an alkaline environment for the system. Quicklime can absorb some of the moisture in the soft soil and reduce the water content. The heat released by absorbing water can also accelerate the hydration reaction. Calcium carbonate can provide a nucleation matrix for the hydration products and promote hydration.

[0035] Aluminum sulfate or alum provides soluble aluminum salts for early reactions, promoting the massive generation of ettringite in the early stages and improving early strength.

[0036] After ultrafine grinding, the soft soil solidifier has a higher specific surface area. On the one hand, the required wetting water increases, thereby absorbing the moisture in the soft soil and reducing the water content; on the other hand, the increase in specific surface area is more conducive to the effective contact of the various components, promoting the hydration reaction to proceed as early as possible, thereby increasing the setting and hardening speed and early strength.

[0037]

[0038]

[0039] Implementation Case 1: Ammonia-soda white mud 10%, mineral powder 48%, steel slag powder 12%, desulfurization gypsum 15%, cement 9%, lime 5%, activator 1%, wherein the activator is aluminum sulfate.

[0040] Implementation Case 2: Ammonia-soda white mud 18%, mineral powder 40%, steel slag powder 11%, desulfurization gypsum 13%, cement 7%, lime 9%, activator 2%, wherein the activator is a mixture of aluminum sulfate and alum.

[0041] Implementation Case 3: Ammonia-soda white mud 24%, mineral powder 45%, steel slag powder 7%, desulfurization gypsum 12%, cement 10%, lime 2%.

[0042] Implementation Case 4: Ammonia-soda white mud 32%, mineral powder 35%, steel slag powder 10%, desulfurization gypsum 10%, cement 3%, lime 8%, activator 2%, wherein the activator is a mixture of aluminum sulfate and alum.

[0043] Implementation Case 5: Ammonia-soda white mud 40%, mineral powder 36%, steel slag powder 5%, desulfurization gypsum 8%, cement 8%, lime 2%, activator 1%, wherein the activator is a mixture of aluminum sulfate and alum.

[0044] Ammonia-soda white mud, mineral powder, steel slag powder, desulfurized gypsum, cement, lime and activator are measured and transported to the ultrafine ball mill for ultrafine grinding. After grinding, they are sent to the powder separator for sorting to obtain a specific surface area greater than 700m 2 / kg of mixture with a specific surface area of ​​less than 700m 2 / kg of mixed material is returned to the ultrafine ball mill for further grinding.

[0045]

[0046] like Figure 1 As shown, the ratio of soft soil solidifying agent to solidified soil sample is 1:10, the soil sample has a moisture content of 40%, a plasticity index of 15%, and an organic matter content of 1.6%. Figure 1 The SEM images not only clearly reveal the details of the solidified soil's microstructure, but also intuitively demonstrate the high performance of the solidifying agent and the scientific nature of its preparation method. These meticulous SEM images provide a deeper understanding of the formation and development of hydration products during the solidification process.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A fast-hardening and early-strengthening soft soil curing agent based on ammonia-alkali white mud, characterized in that: The weight ratio is 10-40% ammonia-soda white mud, 30-60% mineral powder, 0-30% steel slag powder, 5-20% desulfurized gypsum, 0-15% cement, 0-10% lime, and 0-3% activator. The mineral powder is S95 grade granulated blast furnace slag powder with a specific surface area of ​​more than 400m 2 / kg, the steel slag powder is Grade II steel slag powder, and the specific surface area is greater than 350m 2 / kg, the desulfurized gypsum has a dihydrate gypsum content of >90%, is dried to a moisture content of <5%, and has a specific surface area of ​​200-400m 2 / kg, the ammonia-soda mud is a solid waste generated in the process of preparing soda ash by the ammonia-soda process. After filtering, breaking up, airing and drying, the ammonia-soda mud with a moisture content of less than 5% is obtained, and the content of the ammonia-soda mud is greater than 99%. The lime is a mixture of calcium oxide, calcium hydroxide and calcium carbonate, which is obtained by drying and passing through a 0.15mm sieve.

2. The rapid-hardening and early-strength soft soil curing agent based on ammonia-soda white mud according to claim 1, characterized in that: The cement is one or more mixtures of 42.5 grade Portland cement, composite Portland cement or slag Portland cement.

3. The rapid-hardening and early-strength soft soil curing agent based on ammonia-soda white mud according to claim 1, characterized in that: The activator is any one of aluminum sulfate and alum or a mixture of the two.

4. A method for preparing a rapid-hardening and early-strength soft soil curing agent based on ammonia-soda white mud according to any one of claims 1 to 3, characterized in that: The ammonia-soda white mud, mineral powder, steel slag powder, desulfurized gypsum, cement, lime and activator are transported to the ultrafine ball mill for ultrafine grinding. After grinding, they are sent to the powder separator for sorting to obtain a specific surface area of ​​more than 700m 2 / kg product is a fast-hardening and early-strengthening soft soil solidifier.

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