JPS5842226B2 - Construction method that forms hardened material in the ground - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for forming hardened underground materials for the purpose of ground improvement, construction of water-stop walls, ground improvement around existing piles, and tip root hardening.

Conventionally, in order to form a hardened material in the ground, a ground hardening liquid containing cement such as a cement milk liquid, for example, water:cement-1:1.5 (i.e., W/C = 67%), is poured into the ground. It is injected and filled.

However, if such a hardening liquid is left to stand after mixing, the cement particles will settle, and if it is pumped or injected, it will foam. Therefore, if it is injected into the ground, it may cause solid-liquid separation or This has been a drawback in forming a highly reliable and uniform cured product since it entrains air bubbles and impedes uniform filling.

In addition, it has a low viscosity and is often washed away by underground water, so there has been a strong demand for improvements to this method.

This invention aims to improve the above-mentioned problems, and uses a hardening liquid that significantly improves breathing and foaming properties and is stable against underground water to form a hardened product in the ground. It provides a construction method.

This construction method uses basic magnesium carbonate (e.g. (3-5) Mg (
This is a construction method in which 03・Mg(OH)2・(3-7)H2O, etc.) is added to a hardening liquid containing cement, and this is injected into the ground.

An example of basic physical properties when basic magnesium carbonate is added to cement milk, for example, is shown in Table 1.

As shown in Table 1, the addition of basic magnesium carbonate in an amount of 0.2 to 1.0 significantly reduces the breathing rate;
By adding 0%, cement particles do not settle even when left standing even in a fresh state, and the viscosity improves.

Moreover, the compressive strength is increased, and an example thereof is shown in Table 2.

Nao, the upper limit of the amount of basic magnesium carbonate added to cement milk with a W/C of 67% is about 4 mounds, although it varies slightly depending on the temperature.If more than this is added, the cement milk will become jelly-like and pump It becomes difficult to transport or inject, making it unsuitable for use for this purpose.

The method of forming a hardened product of the present invention is achieved by injecting a hardening liquid containing cement into which at least 0.62 kg of basic magnesium carbonate has been added into the ground according to a conventional method.

In this method, a hardening liquid with a low breathing rate and high viscosity is injected, so compared to conventional methods using hardening liquids, solid-liquid separation is less likely to occur as shown in Table 1, resulting in a uniform It is possible to form a hardened product with high properties.

The high viscosity also reduces the chances of it being washed away by underground water.

Even when the conventional cement milk construction method is impossible due to the surrounding fixative being washed away, the construction method of the present invention prevents the washing away and enables stable construction.

Furthermore, a feature of the construction method using this hardening liquid is that foaming can be significantly suppressed by using a small amount of antifoaming agent, compared to conventional hardening liquids containing cement.

For example, as an antifoaming agent, the product name "Nobuco N" manufactured by San Nobro Co., Ltd.
XZ” (fatty acid ester antifoaming agent) to cement 100%
Cement milk added with 0.033cc per g (W/C
67%, basic magnesium carbonate added at 1.0% by weight (based on cement) does not generate any bubbles during pumping.

As a result, in this construction method, by injecting a hardening liquid containing a small amount of antifoaming agent, it is possible to form a hardened product in the ground with very few air bubbles.

In addition to the above-mentioned fatty acid ester antifoaming agents, silicone-based, fatty acid ester-based, metal soap, phosphoric acid ester-based antifoaming agents, etc. can also be used to achieve a great antifoaming effect.

The hardening liquid targeted by this method is not limited to cement milk made of water and cement; the same effect can be achieved even when applied to hardening liquids whose main hardening component is cement. .

Claims (1)

[Scope of Claims] 1. A hardening solution in which basic magnesium carbonate is added in an amount of at least O12 by weight based on the weight of cement, when a hardening liquid containing cement is injected into the ground to form a hardened product. A construction method that forms a hardened material in the ground, which is characterized by injecting liquid into the ground. 2. The construction method for forming a hardened material in the ground according to claim 1, which comprises adding an antifoaming agent to the hardening liquid.