CN1448358A

CN1448358A - Composite silt solidified material

Info

Publication number: CN1448358A
Application number: CN03113373A
Authority: CN
Inventors: 朱伟; 张春雷; 范昭平; 李磊
Original assignee: Hohai University HHU
Current assignee: Hohai University HHU
Priority date: 2003-05-07
Filing date: 2003-05-07
Publication date: 2003-10-15
Anticipated expiration: 2023-05-07
Also published as: CN1301929C

Abstract

The present invention is one kind of composite sludge curing material for curing sludge produced in water engineering and civil engineering. It is cement-based curing material with certain amount of flyash as industrial waste and gypsum added. Through mixing with sludge, it is possible to improve the property of sludge, which has hydroxide water content and low strength, and reusing waste sludge with likely environmental pollution as engineering material. The utilization of industrial waste results in low cost.

Description

Composite sludge solidifying material

Technical Field

The present invention relates to a composite solidifying material for solidifying sludge produced in water conservancy engineering and civil engineering, and the solidified sludge can be used as filling soil for earthwork of road and embankment, etc. Belongs to the technical field of civil engineering materials.

Background

In many water conservancy projects and civil engineering projects such as the dredging of oceans, lakes and rivers, the construction of urban subways, the excavation of foundation pits and the like, a large amount of sludge is generated, the sludge has high water content, high clay content and extremely low strength, can not be directly used as engineering filling soil, and is usually treated by sludge throwing. The disposal method not only pollutes the environment around the mud throwing point, but also occupies a large amount of farmlands or fishponds. In many earthwork projects such as sea filling projects, embankment projects and road projects, a large amount of filling soil is needed, and most of the filling soil is obtained by mining sandstone on land. The invention combines the requirements of environmental protection and civil engineering sustainable development, and converts the waste sludge into the geotechnical renewable resources for utilization by a curing method. The composite sludge solidifying material is developed by adding fly ash and gypsum which are wastes produced in large quantity in industrial production and can promote cement hydration reaction, and selecting an optimal formula, so that the industrial waste can replace the amount of partial cement to the maximum extent, the solidifying effect of the cement is improved, the manufacturing cost is saved, and the aim of treating waste by waste is fulfilled.

Disclosure of Invention

The purpose of the invention is as follows: the composite sludge solidifying material is developed for solving the problem of disposinga large amount of sludge generated in hydraulic engineering and civil engineering and is used for treating waste sludge into solidified soil with good engineering properties. The technical scheme of the invention is as follows: by utilizing the characteristics of cement hydrolysis and hydration reaction, industrial waste capable of promoting cement hydration reaction is added, and the optimal proportion is selected, so that the composite effect of the material is exerted, and the manufacturing cost of the curing material is reduced on the whole. The curing reaction equation of the invention is shown in formulas (1) to (7).

The invention is prepared by uniformly mixing a plurality of raw materials according to a certain proportion, and the raw materials are grey powdery solid, and the main technical characteristic is that industrial waste fly ash and gypsum are added into cement according to a certain proportion and are uniformly mixed, and the cement is prepared by the following components in percentage by weight:

15 to 25 percent of cement

45-83.5 percent of fly ash

1.5-7.5% of gypsum and a preparation process thereof: adding fly ash and gypsum into cement according to the above-mentioned proportion, uniformly mixing them so as to obtain the invented product

The invention has the advantages and effects that: (1) and (3) environmental protection: the invention can reduce the pollution of the waste disposal of the sludge generated in the engineering to the surrounding environment; (2) resource regeneration and utilization: by utilizing the method, the waste sludge is processed into the geotechnical material with good engineering property, and the renewable resources are generated; (3) the price is low: the main raw materials of the invention are a large amount of cheap waste materials generated in industry, and the product priceis cheap; (4) treating wastes with wastes: the invention mainly aims at the problem of treating waste sludge generated in engineering, utilizes waste generated in industry in large quantity, and simultaneously achieves the purpose of treating waste by waste; (5) the treatment effect is good: the invention carries out filling construction after fully mixing the sludge through mechanical stirring, the construction is easy to control, the mixing effect is good, and the curing treatment effect is better; (6) the application range is wide: the invention can be widely used in sea filling engineering (figure 1), road engineering (figure 2) and embankment engineering (figure 3), and can adjust the addition amount according to different engineering requirements, thereby meeting the requirements of various engineering.

Description of the drawings fig. 1-sludge composite type solidifying material used in sea filling engineering fig. 2-sludge composite type solidifying material used in embankment engineering fig. 3-sludge composite type solidifying material used in road engineering

FIG. 1 is a view illustrating that the present invention can cure sludge generated in ocean engineering, and the treated sludge can be directly used for underwater casting construction.

Fig. 2 illustrates that the invention can solidify the sludge generated in the river dredging project, and the treated sludge can be directly used for reinforcing the river bank, thus not only avoiding the pollution of the sludge waste to the environment, but also reducing the cost of taking soil from other places for reinforcing the bank.

Fig. 3 is a view illustrating that the present invention can be combined with a solidification treatment of sludge generated in various works, and the treated sludge can be used for the filling of a roadbed in road works. In road engineering, a large amount of soil for filling is needed, and most of the soil is obtained by arranging soil taking pits along a road, so that the method destroys a large amount of cultivated land. The solidified sludge can effectively avoid the pollution of sludge waste to the environment, and can reduce the quantity and cost of taking soil from other places in road engineering.

Detailed Description

Example 1:

the invention is prepared by uniformly mixing the following components in percentage by weight:

24.4 percent of cement

73.2 percent of fly ash

2.4 percent of gypsum

According to the proportion, 90kg of curing material is added into each cubic meter of sludge, the unconfined compressive strength of the cured sludge can reach 110kPa in 7 days, and the unconfined compressive strength can reach 170kPa in 28 days. The water permeability coefficient of the solidified sludge is less than 10^-5cm/s. Compared with the use of a material of cement, the cost can be saved by 21% to achieve the same curing effect. And the material has good quick hardness (the strength can reach 110kPa after 7 days), and other engineering construction can be carried out on the material soon after construction.

Example 2:

17.5 percent of cement

79.0 percent of fly ash

3.5 percent of gypsum

By utilizing the proportion, 100kg of curing material is added into each side of sludge, the unconfined compressive strength of the cured sludge can reach 100kPa in 7 days, and the unconfined compressive strength can reach 150kPa in 28 days. The water permeability coefficient of the solidified sludge is less than 10^-5cm/s. Compared with the use of a material of cement, the cost can be saved by 18% to achieve the same curing effect. Curing reaction equations (1) to (7) of the composite sludge curing material: hydrolysis reaction formulae (1) to (4): (1) (2) (3) (4) hydration reactions (5) to (7): (5) (6) (7) description of the reaction principle: since much Ca (OH) is generated in the hydrolysis reaction of cement₂(formula 1, 2)Shown in (b) Ca (OH)₂Slightly soluble in water, which, when coated on the cement surface, hinders further reaction of the cement and does not further increase the strength of the solidified soil. Adding SiO as the main component₂The fly ash of (3) can be mixed with Ca (OH)₂Of the formula (5)The reaction produces calcium silicate hydrate crystals, which produce cementation between soil grains, so-called volcanic ash reaction, and can obviously promote the strength increase of the solidified soil. The mechanism of the gypsum solidification reaction is shown in formula (7), and CaO&Al is generated₂O₃·3CaSO₄·32H₂The O is called ettringite and has 32 crystal water, thesolid phase volume is increased by about 120 percent in the forming process, the effects of filling pores and reducing pore diameter can be achieved, and great contribution is made to the strength of the solidified soil.

However, an optimum ratio of these two substances to cement exists because fly ash and gypsum contain a certain amount of CaO (about 20% in fly ash and about 30% in gypsum) which, during the setting process, causes a certain expansion of the volume of the set soil and, when the expansion amount is appropriate, promotes the strength of the set soil. However, when the swelling action is too large, the cementation between the grains of the soil which is already formed by the calcium silicate hydrate is destroyed, and the strength is reduced. Therefore, the key point of the invention is that the fly ash and gypsum are added in amounts to achieve the most appropriate ratio of expansion filling and cementation during the curing process. The combination advantages of various materials are exerted on the whole, thereby achieving the purposes of promoting the curing effect and reducing the manufacturing cost.

Claims

1. The composite sludge solidifying material is characterized by comprising the following raw material components in percentage by weight:

15 to 25 percent of cement

45-83.5 percent of fly ash

1.5-7.5% of gypsum. The preparation process comprises the following steps: adding fly ash and gypsum into cement according to the above proportion, and mixing uniformly to obtain the cement.

2. The composite sludge solidification material as claimed in claim 1, wherein the composite sludge solidification material comprises the following raw material components in percentage by weight:

24.4 percent of cement

73.2 percent of fly ash

2.4 percent of gypsum.

3. The composite sludge solidification material as claimed in claim 1, wherein the composite sludge solidification material comprises the following raw material components in percentage by weight:

17.5 percent of cement

79.0 percent of fly ash

3.5 percent of gypsum.