CN111423080B

CN111423080B - Foundation excavation slurry stabilizing and curing agent and preparation and use method thereof

Info

Publication number: CN111423080B
Application number: CN202010134367.8A
Authority: CN
Inventors: 李雁; 王福喜; 李捷; 王远; 李琦; 梁华石; 韩慧
Original assignee: Nanjing Environment Group Co ltd; Nanjing City Construction Investment Holding Group Co ltd
Current assignee: Nanjing Environment Group Co ltd; Nanjing City Construction Investment Holding Group Co ltd
Priority date: 2020-03-02
Filing date: 2020-03-02
Publication date: 2022-09-16
Anticipated expiration: 2040-03-02
Also published as: CN111423080A

Abstract

The invention provides a stable curing agent for foundation excavation slurry and a preparation and use method thereof, wherein the curing agent is prepared by mixing 45-80% of mixture of volcanic ash silica, silica gel compound and the like and 18-42% of inorganic calcined paper pulp ash mixed powder. The invention has the advantages that: 1) the soil particles can be instantly solidified; 2) the use amount is greatly reduced (the weight ratio is 0.08-0.55); 3) the improved soil has stable property and can be directly used as backfill soil; 4) the environmental pollution is reduced; 5) can not be decomposed by microorganisms such as bacteria in the soil, and can maintain the strength of the solidified sandy soil for a long time.

Description

Foundation excavation slurry stabilizing and curing agent and preparation and use method thereof

Technical Field

The invention relates to a stable curing agent for foundation excavation slurry and a preparation and use method thereof, belonging to the technical field of building materials.

Background

The excessive foundation excavation slurry in the urban building foundation construction site is usually buried as waste due to high collection cost, complex transportation and intermediate treatment, high manpower and material resources consumption and high transportation cost. Currently, national policies require technical development with the goal of improving the effective utilization of various resources and reducing the cost of regeneration treatment. The mainstream treatment method of the foundation excavation slurry in the prior art is a physical dehydration method using equipment such as filter pressing and a centrifuge, and a solidification treatment method using organic and inorganic dehydrating agents (such as iron-aluminum polymer, lime, waste paper and the like) for water absorption/dehydration. However, the above-described solidification treatment technique is difficult to apply to a slurry for excavation of a ground having an extremely high water content (100% by mass or more).

The curing materials used in the prior art described above produce complex chemical reactions leading to strong self-hardening phenomena, the maximum required water content being about 60%; wherein, the absorption amount of the hydration reaction crystal water is about 25% in the case of using the portland slag cement, and about 35% in the case of using the ordinary portland cement setting mud; if the water content is higher than 35%, slurry is reflected to the foundation excavation slurry and cannot be completely cured, and in order to increase the curing effect, a large amount of cement needs to be used, so that the cost problem is obvious; in addition, when the cement-based or lime-based stable curing material is used for curing, the slurry becomes strong alkaline, and cannot be directly recycled as planting greening soil, and even causes environmental pollution.

In the prior art, a method for adjusting the moisture content of slurry by using cheap and easily available quick lime exists: in the adjusting process of using the quicklime, the reaction heat between the water contained in the slurry and the quicklime is utilized to quickly evaporate the redundant heat, so that the slurry solidification treatment can be completed in a short time; however, this method generates a large amount of heat, and the central portion of the slurry often generates high temperature, resulting in deterioration of the working environment. Other curing methods for on-site construction typically require hours of agitation, which can create problems in routine operations. As described above, the operability of the method of treating conventional high water content mud using cement or lime as a stabilizing treatment material is very problematic.

For the foundation excavation slurry containing organic matters such as humus, fluoric acid and the like, the organic matters are adsorbed on the surface of cement particles in the curing process, so that the hydration reaction of cement is hindered, and the treatment effect is not ideal. In the prior art, the method of using lime and blast furnace cement together and using pretreated foundation excavation slurry and high molecular organic polymer material together is adopted to improve the curing performance of the cement; the method for preparing granular soil for greening by mixing incineration ash and foundation excavation slurry with high water content is also used for preparing the solidified material for improving the high-water-content construction slurry, and the solidified material can reduce the alkaline pH value and reduce the negative effect on plants by inhibiting the using amount of strong alkaline cement. In the implementation process of the method, a large number of repeated tests are needed to determine the optimal composition ratio according to the characteristics of the foundation excavation slurry, the time period is long, the cost required by curing treatment is increased, and the method is not suitable for being used in a large range.

Disclosure of Invention

The invention aims to solve the defects of the existing foundation excavation slurry curing method and curing material, and provides a foundation excavation slurry stabilizing and curing agent and a preparation and use method thereof; compared with the common foundation excavation slurry curing agent, the product of the invention can be added with a small amount of the curing agent to stably cure the foundation excavation slurry, and provides an efficient and stable scheme for the curing treatment technology of the foundation excavation slurry.

The technical solution of the invention is as follows: a stabilization curing agent for foundation excavation slurry is formed by mixing 45-80% of mixture of volcanic ash silica and silica gel compounds by mass fraction and 18-42% of inorganic calcined paper pulp ash mixed powder by mass fraction, and also contains 5-18% of bentonite by mass fraction; wherein the volcanic ash silica ultrafine grain powder with the grain diameter of less than 18 mu m accounts for 20 to 40 percent by mass, and the volcanic ash silica powder with the grain diameter of 18 mu m to 0.45mm accounts for 35 to 62 percent by mass. In actual use, 0.08 to 0.55 parts by weight of a solidification improver for the stability of a ground excavation slurry is added to 100 parts by weight of a ground excavation slurry and mixed.

Further, the mixture of the pozzolana silica and the silica gel compound comprises the following components in percentage by mass: 62 to 72 percent of silicon compound, 10 to 20 percent of alumina, 2 to 5 percent of sodium oxide, 2.5 to 3.5 percent of potassium oxide, 1 to 5 percent of ferric oxide and 1 to 6 percent of calcium oxide; the particle size of the ash content of the paper pulp is less than 0.25mm, and the mass fraction content of each component is as follows: 45-62% of silicon dioxide, 12-31% of aluminum oxide, 3-8% of ferric oxide and 1.5-6% of calcium oxide.

The preparation method comprises the following steps:

1) adding a trace amount of hydrochloric acid or sulfuric acid into superfine powder of volcanic ash silica and silica gel compounds with the mass fraction of 30-72% and the particle size of 18 mu m-0.55mm, mixing and inorganic calcining at the temperature of 180-425 ℃, preferably heating at the temperature of 260-325 ℃, then cooling to obtain a powdery mixture, and activating the hydration reaction property of the powdery mixture;

2) mixing the powdery mixture obtained in the step 1) in a weight ratio of 100: (18-82), and mixing and calcining at 550-820 ℃, preferably at 620-710 ℃, to form inorganic calcined powder having 6 hydroxyl groups.

3) Crushing the inorganic sintering powder obtained in the step 2) by a crusher to prepare the modifier powder for stabilizing and curing the foundation excavation slurry.

Compared with the prior art, the invention has the advantages that:

1) the mud can be instantly solidified, and the mud is modified into sandy soil which hardly flows;

2) compared with the common slurry modifying agent, the use amount is greatly reduced, and the stable solidification treatment is carried out on the foundation excavation slurry;

3) the solidified and modified sandy soil has stable property, the improved soil can be directly used as backfill soil, and the fluidity of the improved soil can not be recovered due to factors such as vibration during conveying;

4) the solid components can be solidified almost completely, and even under the condition of residual moisture, the water quality clarity is very high, so the environment is not polluted;

5) the soil conditioner using the inorganic sintered powder is not decomposed by microorganisms such as bacteria in the soil, and can maintain the strength of the solidified sandy soil for a long time.

Drawings

FIG. 1 is a graph showing the comparison of the curing effect of the mixture of the slurry samples with different water contents and the curing agent of the present invention.

Detailed Description

A stabilizing and curing agent for foundation excavation slurry is prepared by mixing 45-80% of mixture of pozzolan silica and silica gel compounds and 18-42% of pulp ash mixed powder subjected to inorganic calcination, wherein the mass fraction of pozzolan silica ultrafine grain powder with the grain size of less than 18 mu m is 20-40%, and the mass fraction of powder with the grain size of 18 mu m-0.45mm is 35-62%.

In the mixture of the volcanic ash silica and the silica gel compound, the ultrafine powder of the silica gel compound can be used alone or mixed with the volcanic ash silica.

The foundation excavation slurry stabilizing and curing agent also contains bentonite with the mass fraction of 5-18%; a modifier for the slurry of foundation excavation containing bentonite can adsorb and capture the superfine clay particles in the slurry and increase the clarity of residual water in the process of solidification treatment.

The volcanic ash silica is a general term for white volcanic ash deposits, and the mixture of the volcanic ash silica and the silica gel compound comprises the following components in percentage by mass: 62 to 72 percent of silicon compound, 10 to 20 percent of alumina, 2 to 5 percent of sodium oxide, 2.5 to 3.5 percent of potassium oxide, 1 to 5 percent of ferric oxide and 1 to 6 percent of calcium oxide.

The particle size of the ash content of the paper pulp is less than 0.25mm, and the mass fractions of the components are as follows: 45-62% of silicon dioxide, 12-31% of aluminum oxide, 3-8% of ferric oxide and 1.5-6% of calcium oxide.

The invention relates to a preparation method of a stable curing agent for foundation excavation slurry, which comprises the following steps:

In actual use, 0.08 to 0.55 parts by weight of a stabilizer modifier for the excavation slurry for the foundation is added to 100 parts by weight of the excavation slurry for the foundation and mixed; when the slurry improver is added and mixed in the slurry, the slurry improver undergoes a water-activating reaction or the like with calcium present in the slurry, and slurry particles are bonded to each other. Then, the pulp ash in the slurry modifier holds moisture in the slurry mixture, and ettringite (needle crystal hydrate) and the like are continuously generated using the retained moisture.

If the content of the mixture of pozzolana silica and silica gel compound (rice husk charcoal, etc.) is less than 45%, the amount of ettringite produced is too small, and the amount of slurry improver required to stabilize the slurry increases; on the other hand, when the mixture exceeds 80%, the water content of flocs formed in the sludge is not easily separated, so that it cannot be effectively used as a sludge improver.

When the ash content of the paper pulp is less than 18 percent, enough composite water required for producing the ettringite cannot be reserved, so the ettringite cannot be continuously generated; on the other hand, when the ash content of the pulp exceeds 42%, the drying time of the slurry becomes long because it excessively absorbs the moisture in the slurry.

In conclusion, the invention is formed by mixing 45-80% of mixture of pozzolana silica and silica gel compounds by mass fraction and 18-42% of pulp ash mixed powder subjected to inorganic calcination by mass fraction, and the mixture of the pozzolana silica and the silica gel compounds (rice husk carbon and the like) is reacted with calcium existing in slurry to generate ettringite. The effective component of the modifier for the slurry for foundation excavation contains 6 hydroxyl groups, and in the process of forming ettringite, the inorganic calcined powder containing 6 hydroxyl groups consumes a large amount of water as crystal water and composite water required by hydration reaction. At this time, since the pulp ash absorbs and retains a large amount of water in the slurry, ettringite is continuously generated by the water retained in the pulp ash, thereby achieving an effect of rapidly and stably solidifying the slurry for excavation of the foundation.

FIG. 1 is a graph showing the comparison of the curing effect of the slurry samples with different water contents and the curing agent of the present invention, and the basic ratio of the slurry and the curing agent is shown in the following table.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A stabilization curing agent for foundation excavation slurry is characterized by being formed by mixing 45-80% of mixture of pozzolana silica and silica gel compounds by mass and 18-42% of pulp ash mixed powder subjected to inorganic calcination by mass, wherein the pozzolana silica ultrafine grain powder with the grain diameter of less than 18 mu m accounts for 20-40% by mass, and the pozzolana silica powder with the grain diameter of 18 mu m-0.45mm accounts for 35-62% by mass;

the mixture of the volcanic ash silica and the silica gel compound comprises the following components in percentage by mass: 62 to 72 percent of silicon compound, 10 to 20 percent of alumina, 2 to 5 percent of sodium oxide, 2.5 to 3.5 percent of potassium oxide, 1 to 5 percent of ferric oxide and 1 to 6 percent of calcium oxide;

the particle size of the ash content of the paper pulp is less than 0.25mm, and the mass fraction content of each component is as follows: 45-62% of silicon dioxide, 12-31% of aluminum oxide, 3-8% of ferric oxide and 1.5-6% of calcium oxide;

the preparation method of the foundation excavation slurry stabilizing and curing agent comprises the following steps:

1) adding a trace amount of hydrochloric acid or sulfuric acid into superfine powder of volcanic ash silica and silica gel compounds with the mass fraction of 30-72% and the particle size of 18 mu m-0.55mm, mixing and inorganic calcining at the temperature of 180-425 ℃, and then cooling to obtain a powdery mixture, and activating the hydration reaction property of the powdery mixture;

2) mixing the powdery mixture obtained in the step 1) in a weight ratio of 100: (18-82) mixing the pulp ash and calcining at 550-820 ℃ to form inorganic calcined powder with 6 hydroxyl groups;

2. The agent for stabilizing and curing excavation slurry of claim 1, wherein 0.08 to 0.55 parts by weight of a stabilizer modifier for excavation slurry is added to 100 parts by weight of excavation slurry and mixed in actual use.