Preparation of a modified tuff rock powder-based curing agent and method for in-situ curing of construction waste soil

Abstract

The present invention discloses a method for preparing a modified tuff rock powder-based curing agent and for in-situ curing of engineering construction waste. The method aims to overcome the problems of low activity and low resource utilization efficiency of tuff rock powder in the prior art, and provides a tuff rock powder-based curing agent for curing engineering construction waste prepared by a combined modification method of lignin, sodium silicate and sodium hydroxide. The method also provides an in-situ curing method for engineering construction waste. The tuff rock powder-based curing agent prepared by the technical solution of the present application for curing engineering construction waste has the advantages of being green, low-carbon and low-cost, can replace high-energy-consuming cement, and can simultaneously improve the resource utilization value of tuff rock powder and engineering construction waste.

Description

Technical Field

[0001] The invention relates to the field of engineering construction waste soil solidification and improvement, and in particular to the field of preparing a modified tuff rock powder-based solidifying agent and using the agent for improving engineering construction waste soil. Background Art

[0002] Construction waste is an important component of construction by-products. Reasonable disposal of construction waste and resource utilization is not only an urgent problem to be solved, but also breeds a huge market. Construction waste solidification technology can effectively improve the mechanical properties of construction waste and expand the resource utilization scenarios of waste. Forming an economical and simple waste solidification construction process and corresponding waste solidification products is one of the best ways to deal with construction waste at present. Conventional waste solidifiers often use cement, fly ash, slag, etc., but with the large-scale promotion and use of these solidifier raw materials in the concrete field, the prices of cement, fly ash, etc. have risen sharply, especially the cement production process has a large carbon emission. With the implementation of the "dual carbon" concept, the use of such traditional solidifiers is undoubtedly not the best choice.

[0003] Tuff, a new inorganic non-metallic mineral resource, is widely distributed. It contains primary components such as SiO2, Al2O3, K2O, and Na2O, as well as secondary components such as CaO, MgO, TiO2, FeO, and Fe2O3. It exhibits a degree of chemical activity similar to that of volcanic ash and fly ash. Tuff dust, a byproduct of tuff sand production, is often transported and disposed of in landfills. This is undoubtedly a waste of resources. Summary of the Invention

[0004] The purpose of the present invention is to overcome the high cost of traditional curing agents used in the prior art and the low resource efficiency of tuff stone powder and engineering construction waste, provide a method for modifying tuff stone powder, and at the same time propose a method for curing and improving engineering construction waste with modified tuff stone powder. The technical solution of the present invention uses modified tuff stone powder to solidify engineering construction waste with the advantages of low cost and simple operation.

[0005] To achieve the above object, according to one aspect of the present invention, the present invention adopts the following technical solution:

[0006] A method for preparing a modified tuff stone powder-based curing agent, characterized in that the method comprises the following steps:

[0007] The tuff stone powder collected in the aggregate production process of mining is first passed through a 200-mesh sieve, and then the sieved tuff stone powder is placed in a mixed aqueous solution of sodium hydroxide, water glass and sodium lignin sulfonate, and reacted at 20-25°C for 24-48 hours to obtain a modified tuff stone powder-based curing agent slurry.

[0008] Preferably, the mass ratio of the sodium hydroxide to water is 1:20-30.

[0009] Preferably, the mass ratio of sodium hydroxide to water glass is 1:4-5, wherein the modulus of water glass is 3.3-3.7.

[0010] Preferably, the mass ratio of sodium lignin sulfonate to water is 1:200-300.

[0011] Preferably, the mass ratio of sodium hydroxide to tuff stone powder is 1:30-60.

[0012] The present application also provides a method for treating construction slag by solidifying modified tuff stone powder, the method comprising the following steps: adding the modified tuff stone powder-based solidifying agent slurry prepared above to the construction slag, with the mass ratio of tuff slurry to slag being 1:5-10, and adjusting the water content of the system to the optimal water content; + 0.2%, stir evenly, compact and cure for not less than 7 days.

[0013] Therefore, the present invention has the following beneficial effects:

[0014] (1) This method modifies low-activity tuff rock powder and activates its activity for use in the solidification of construction waste, which is of great significance in treating waste with waste, reducing solidification costs, and improving the resource value of construction waste.

[0015] (2) The preparation method of this scheme is simple to operate, can react at room temperature, and has low energy consumption.

[0016] (3) The present invention uses alkali to jointly excite stone powder and lignin. On the basis of alkali excitation of stone powder, it also promotes hydroxylation of lignin, improves the activity of lignin, strengthens the combination with stone powder, and is beneficial to the solidification reaction with engineering construction waste.

[0017] (4) The tuff rock powder-based curing agent containing lignin prepared by the present invention is characterized in that when interacting with construction waste soil, the alkali-activated tuff rock powder acts as an inorganic binder, while the lignin plays a role in conditioning the surface properties of the construction waste soil particles, compressing the double electrical layer, reducing the negative charge on the surface of the soil particles, and connecting the polymer chains, thereby promoting the bonding between the soil particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is a comparison of the unconfined strength performance results of soil stabilized using tuff rock powder-based solidifier. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] Example 1

[0021] This embodiment provides a method for preparing a modified tuff rock powder-based curing agent, the method comprising the following steps:

[0022] Step S1: First, tuff rock powder is passed through a 200-mesh sieve. The chemical composition table is shown in Table 1:

[0023] Chemical formula <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[TiO2]]> MnO content(%) 65.1 20.6 4.21 3.88 2.58 2.44 0.566 0.219 0.119

[0024] Step S2: preparing a mixed solution of sodium hydroxide, water glass, sodium lignin sulfonate and water, wherein the ratio of sodium hydroxide: water glass: water is 1:5:20, and the mass fraction of sodium lignin sulfonate is 0.3%.

[0025] Step S3: placing tuff stone powder passing through a 200-mesh sieve into a mixed aqueous solution of sodium hydroxide, water glass and sodium lignin sulfonate, controlling the reaction temperature to 20° C., and stirring for 24 hours to obtain a modified tuff stone powder-based curing agent slurry.

[0026] Example 2: This example provides a method for in-situ solidification of construction waste using a modified tuff rock powder-based solidifying agent, the method comprising the following steps:

[0027] The modified tuff stone powder-based curing agent slurry prepared in Example 1 was added to construction waste soil. The chemical composition of the construction waste soil is shown in Table 2. The mass ratio of tuff slurry to waste soil was 1:5-10. The moisture content of the system was adjusted to the optimal moisture content, stirred evenly, compacted, and cured under standard conditions for 7 days.

[0028] Table 2: Chemical composition of construction waste

[0029] Chemical formula <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[K2O]]> <![CDATA[P2O5]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[TiO2]]> MnO content(%) 56.1 21.6 3.23 0.339 13.6 0.364 1.71 2.95 0.184

[0030] Control group 1: Cement was added to the construction waste soil at a rate of 7% by internal admixture method, the optimum moisture content was maintained, the soil was stirred and compacted, and then cured for 7 days under standard conditions.

[0031] Control group 2: Unmodified stone powder was added to the construction waste soil at an internal mixing rate of 20%, the optimum moisture content was maintained, the mixture was stirred and compacted, and cured for 7 days under standard conditions.

[0032] The unconfined compressive strength of the cured structures of Example 2, Control Group 1, and Control Group 2 was measured. The measured data are shown below:

[0033] Table 3, and see Figure 1

[0034]

[0035]

[0036] The experimental results show that the unmodified stone powder has low solidification activity and the unconfined strength is only 0.336Mpa, but the unconfined strength of the modified solidified soil is greatly improved. When the dosage is 15%, it can replace 7% of the cement dosage and reach a solidified soil strength of 1.5Mpa. It can also achieve the effect of reducing costs and reusing fossil powder and construction waste.

Claims

1. A method for preparing a modified tuff stone powder-based curing agent, characterized in that: The method comprises the following steps: The tuff stone powder collected in the aggregate production process of mining is first passed through a 200-mesh sieve, and then the sieved tuff stone powder is placed in a mixed aqueous solution of sodium hydroxide, water glass and sodium lignin sulfonate, and reacted at 20-25°C for 24-48 hours to obtain a modified tuff stone powder-based curing agent slurry.

2. The method for preparing a modified tuff stone powder-based curing agent according to claim 1, wherein: The mass ratio of the sodium hydroxide to water is 1:20-30.

3. The method for preparing a modified tuff stone powder-based curing agent according to claim 1, wherein: The mass ratio of the sodium hydroxide to the water glass is 1:4-5, wherein the modulus of the water glass is 3.3-3.

7.

4. The method for preparing a modified tuff stone powder-based curing agent according to claim 1, wherein: The mass ratio of sodium lignin sulfonate to water is 1:200-300.

5. The method for preparing a modified tuff stone powder-based curing agent according to claim 1, wherein: The mass ratio of the sodium hydroxide to the tuff stone powder is 1:30-60.

6. A method for in-situ solidification of construction waste, characterized by: The modified tuff rock powder-based curing agent slurry prepared by any preparation method described in any one of claims 1-5 is added to the construction waste soil, the mass ratio of the tuff rock powder-based curing agent slurry to the waste soil is 1:5-10, and the moisture content is adjusted to the optimal moisture content ±0.2%, and the mixture is stirred evenly, compacted, and cured for not less than 7 days.

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