JPH0161129B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is widely applied to the construction of earth retaining walls and water-stop walls because it is easy to construct, has low construction costs, and is a low-pollution construction method. In the soil pile construction method, earth, sand, water, cement,
A method of reusing (recycling) surplus liquid mixed with bentonite. Specifically, the surplus liquid generated during soil pile creation is separated into a liquid containing earth and sand components and a liquid containing cement components. This invention relates to a method for reusing liquid for soil pile creation.

To explain in more detail, there are two ways to dispose of the surplus liquid generated during soil pile construction: ○1) Dumping it as industrial waste using a vacuum truck; ○B) Mixing a solidifying agent with the surplus liquid and solidifying it, then disposing of it using a dump truck. ○C A method of mixing a solidifying agent into the surplus liquid to solidify it and reusing it as a landfill at ports or sites, ○D A method of separating the surplus liquid into a liquid containing earth and sand components and a liquid containing cement components. A known method is to reuse the liquid containing cement components as material for creating soil piles, but in ○a, all of the surplus liquid generated in large quantities must be disposed of as industrial waste, and the disposal costs are enormous. ○B and ○C have the disadvantages of ○B and ○C, and furthermore, the material cost of solidifying agent, mixing processing cost, labor cost, and machine damage costs are added, making the disposal cost even more enormous. Compared to these, ○ni is the most rational and economical,
The method of the present invention relates to this method.

By the way, the conventional method (○2) is a method of reusing the cement component-containing liquid separated from the earth and sand component as it is as a soil pile construction material, but in this case, there are problems listed below and it is not practical.

The cement component in the excess liquid gels and its viscosity increases over time, making it impossible to pump up the liquid during the liquid recovery process. Furthermore, when water is added to reduce the viscosity, the amount of excess liquid increases, which increases processing costs accordingly.

The recycled components in the surplus liquid are water, cement, and bentonite excluding soil and sand, but when the soil and recycled components are separated, cement components adhere to the discharged soil (80 to 90% of the cement components). )
However, most of the cement components are wasted along with the earth and sand.

In view of the deterioration of the cement in the recycled liquid and the resulting reduction in pile strength, the effectiveness of recycled cement components is low, and therefore the effect of saving cement materials in soil pile construction in general is small.

In view of the above-mentioned circumstances, the present invention makes it possible to reuse the cement components in the surplus liquid as effectively as possible, thereby making it possible to expect a great saving effect on cement materials necessary for soil pile construction, and to treat the soil components. The purpose is to propose a method that can reduce costs.

The method for reusing soil pile surplus liquid according to the present invention devised to achieve the above object is to add 0.4 to 1.0 percent by weight of a cement admixture to delay the solidification of cement into cement milk for soil pile construction. The effects of the present invention having such features are as follows.

(1) Since a cement admixture with a retarding effect is mixed into the cement milk in advance, the increase in viscosity due to gelation of the cement components in the excess liquid can be suppressed as much as possible, thereby making it possible to recover the excess liquid. There are no inconveniences such as the impossibility of pumping up and the increase in liquid volume due to the use of dilution water.

(2) As mentioned above, since the gelation of the cement component is suppressed to the utmost, it is easy to efficiently separate the surplus liquid into earth and sand and the cement-containing liquid, and the residual rate of the cement component in the reused liquid is improved. When excess liquid is separated using the conventional method, the cement components in the excess liquid gel and increase in viscosity, making it difficult to separate the cement components attached to the earth and sand particles. 90% of the cement components were disposed of along with soil and sand. On the other hand, the method of the present invention, which actively suppresses the increase in viscosity due to gelation of cement, can reduce the adhesion rate of cement to soil and sand components, as shown in the graph of Figure 3. Component residual rate can be improved. Therefore, the absolute amount of soil components to be dumped is reduced compared to the conventional method, and it is possible to reduce the processing cost of the soil components, and also to expect a significant reduction in cement materials required for soil pile construction.

(3) Furthermore, since the gelation of the cement components is suppressed, there is almost no problem with the strength of the soil pile even if the surplus liquid is reused after being left for more than a day (30 hours). The surplus liquid obtained by the conventional method starts a cement hardening reaction as time passes, and as seen in the increase in viscosity due to gelation in FIG. 2, the reaction starts rapidly within a short period of time. For this reason, if conventional surplus liquid was used, the cement components that had undergone reaction solidification would be reused, and as shown in the graph in Figure 4 (b), the strength of the cement would decrease due to the reuse of the deteriorated surplus liquid. . In contrast, in the method of the present invention, the solidification of cement components is suppressed, so there is no significant deterioration of cement unlike in the conventional method, and even when using surplus liquid that has been left for a certain period of time, the graph in Figure 4 (b) As shown in , the decrease in soil pile strength can be suppressed.

By combining the above (1) to (3), the effective cement components in the surplus liquid can be reused as effectively as possible, the amount of cement material required for soil pile construction can be significantly reduced, and at the same time industrial waste can be reduced. This has resulted in a significant economic effect as it has reduced the occurrence of this and significantly reduced the costs involved.

Examples of the method of the present invention will be described below in detail based on the drawings. 1 is an excavator for creating soil piles;
As a result, a vertical hole 2 is excavated in the ground, and the bentonite and cement milk injected into the vertical hole 2 through a pump 3 are mixed and stirred with the earth and sand resulting from the excavation, thereby creating a soil pile SP. are created in sequence. 4 is a cement milk mixing tank, into which cement supplied at appropriate ratios through tanks 5, 6, 7, and 8, a cement admixture for delaying cement solidification, water, and bentonite are mixed and prepared. Above, the structure is such that cement milk is injected into the vertical hole 2 via the pump 3. 9
is a separation device that separates the surplus liquid a generated during the construction of the soil pipe SP and sent through the pump 10 into a liquid containing earth and sand components and a liquid containing cement components, and the separated earth and sand components are disposed of. While the recycled liquid containing cement components is dumped via a dump truck or the like received in the soil tank 11,
After being stored in the tank 12, it is supplied into the mixing tank 4 and reused for creating the soil pile SP. This reuse makes it possible to reduce the amount of cement used. 1 in the diagram
3 is a valve, and as the above-mentioned cement admixture, one whose main component is lignin sulfonate, oxycarboxylate, magnesium silicofluoride, etc. is used.

The following are the results of experiments conducted by the applicant to demonstrate the effects of the method of the present invention, and in each experiment, a carboxylic acid-based retarder was used as the cement admixture.

[] Effect on viscosity due to addition of cement admixture - As shown in the graph in Figure 2,
It was clear that if the admixture was added in an amount of 0.8% by weight, there would be no problem in pump-up if the standing time was about 30 hours (hr).

[] Adhesion rate of cement components to soil and sand components due to the addition of cement admixtures (residual rate of cement components in recycled liquid) - As shown in the graph in Figure 3, the size of the soil and sand components (particle diameter) Although there are some differences depending on the amount, adding 0.8% by weight of the admixture will improve the separation of the cement component and the sand component, and the residual rate of the cement component in the recycled liquid will be reduced.
It was clear that about 80% could be expected.

[] Effect on soil pile quality (strength) by reusing liquid containing cement admixture - As shown in the graphs in Figure 4 A and B,
It was found that the admixture plays an important role in the final strength (unconfined compressive strength) of the pile, and that adding 0.8% by weight of the admixture allows sufficient reuse even after 30 hours of standing time.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of the soil pile surplus liquid reuse method according to the present invention, and FIG. 1 is an overall system diagram, and FIGS. 2, 3, and 4 A and 4 are graphs showing experimental results.

Claims (1)

[Claims] 1 A method of separating surplus liquid generated during the creation of soil pile SP into soil and cement components and reusing the separated cement component-containing liquid for creating soil pile SP, which method is used for creating soil pile SP. 1. A method for reusing surplus soil pile liquid, characterized in that 0.4 to 1.0 weight percent of a cement admixture for retarding the solidification of cement is mixed into cement milk in advance.