JPS61137916A - Sheathing wall work using slow-curable soil cement mortar - Google Patents

Abstract

PURPOSE:To smoothly erect a core material by allowing the delaying effect of coagulation of a soil cement mortar to exhibit while suppressing the lowering of the strength of the mortar by adding a bleeding inhibitor to the soil cement mortar. CONSTITUTION:In a sheathing work to erect a core material into a soil cement mortar placed, a bleeding inhibitor is added to the mortar to allow the coagulation of the mortar to delay. As the bleeding inhibitor, a methyl cellulose-based one is used in an amount of 0.4-1.2wt.% on the basis of the hardener of the soil cement mortar. Since the delaying effect of coagulation of the mortar can be exhibited while suppressing the lowering of its strength due to the presence of the bleeding inhibitor, smooth erection of the core material can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a soil mortar retaining wall construction method that effectively delays the time from soil mortar placement to core erection.

The soil mortar earth retaining wall construction method is a construction method in which soil mortar is created by adding soil materials such as excavated soil and water to a solidifying material such as cement material or bacillus material, and this is forced into a trench. While the installed soil mortar has not yet solidified, it is recommended to erect H-shaped steel as a core material to form an earth retaining wall (this has been done and has been successfully used as a temporary earth retainer for subway construction etc.). In the soil mortar earth retaining wall construction method, which uses core materials such as
For example, in the case of a pouring depth of 20 m, it takes about 5 hours on average from the start of soil mortar pouring to the completion of core material (steel material) erection. As the depth increases, the time required to construct the steel material increases accordingly, and at a depth of about 50 m, the time required to construct the steel material increases accordingly.
It will take 0 hours. In conventional construction methods, if more than 5 hours have elapsed since the start of soil mortar pouring, the soil mortar will solidify, making it impossible to erect steel.

The present invention aims to solve this problem. For this purpose, the present inventors investigated various formulations for retarding the setting of soil mortar ψ.1 Although the retarding effect is small, it has been found that anti-breathing agents, which are normally used to prevent breathing in concrete, are highly effective in retarding the setting of soil mortar. That is, the present invention provides a soil mortar retaining wall construction method in which a core material is built into poured soil mortar, by adding an appropriate amount of an anti-breathing agent, which is normally used to prevent breathing of concrete, to the soil mortar. The present invention provides a soil mortar retaining wall construction method that is characterized by delaying the setting of soil.

Suitable examples of this anti-breathing agent include 1) water-soluble polymeric materials commonly used for preventing bleeding of concrete, 9 such as those containing methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinyl alcohol, etc. as a main ingredient. In particular, commercially available anti-breathing agents include methylcellulose-based products under the trade name "Hi-Metrose" (manufactured by Shin-Etsu Chemical Co., Ltd.), "Metolose" (manufactured by Shin-Etsu Chemical Co., Ltd.), and "Marborose" (Matsumoto Yushi Pharmaceutical Co., Ltd.). It was found that ``Hymetolose'' is particularly suitable.The optimal range for the amount of such anti-breathing agent to be blended varies depending on the type, but generally speaking, it is In the case of the above-mentioned "Himetrose", which is preferably blended in an amount of 0.2 to 1.2% by weight, 0.4 to 1.2% by weight, preferably 0.4% by weight, based on the solidifying material. ~0
．． It is preferable to mix it in an amount of 8% by weight.

The present invention will be specifically explained below using representative test examples.

A sample soil mortar consisting of a secondary solidifying material and a slurry was used in the following formulation.

Solidifying material: blast furnace cement (slag content 30-60%).

Slurry: Saitama clay soil (77% less than silt).

ur=56.3%+wp-32.1%, Ip-2
4,20°G5-2.53. W-58%) Mixture; Solidifying agent-Line rise In? 200 Kg or 250 Kg per slurry - 1220 kg per 1 d (11-
275%) for this soil mortar during its mixing.

Super retarder A or B, anti-breathing agent C
agent or D agent at a rate of 0.0% to the solidified weight, respectively.
It was added in an amount of 4% or 0.8%. however.

Super retardant A agent; polyol complex (trade name Hozolith 100XR)
.

Agent B: Oxycarboxylic acid salt (trade name: Varituri-T) Anti-breathing agent Agent C: Methylcellulose (trade name: Hymetrose) Agent D: Polyvinyl alcohol.

The soil mortar of each composition was subjected to a Broctor penetration test every hour after kneading, and the relationship between the rise time of the penetration resistance value and the addition rate of each additive was investigated. The results are shown in Figure 1. Here, the rise time of the penetration resistance value 9 is the time corresponding to the point where the tangent before the rise and the tangent after the rise intersect, based on the relationship between the elapsed time and the actually measured penetration resistance value.

From the results shown in Figure 1, it is clear that Agents C and D, which serve as anti-precipitation agents, have a greater effect on delaying the rise time, that is, retarding the setting of soil mortar, than Agents A and B, which are super retardants. I can see it appearing. More specifically,
For retarder A, the rise time increases linearly as the addition rate increases.

In addition, with retarder B, the rise time increases even with a small amount added, but the effect is saturated with a small amount, whereas with anti-prise agent C, the rise time increases dramatically with a small amount. Further, when the amount of the anti-pleasing agent (approximately 0.4%) is exceeded, the rise time increases rapidly.

Table 1 below calculates the possible time for erecting steel materials during construction using the soil mortar retaining wall construction method based on the rise time test results, and summarizes the results.

From the results in Table 1, it can be seen that the steel material construction time is the longest when 0.8% of C agent is added, and construction can be performed for up to about 12 hours after pouring. Considering this result in relation to the rise time in Figure 1, it can be seen that even when 0.8% agent C is added, the increase in rise time is small; This means that it will take a long time to complete the process, so I have to wait.

This indicates that the soil mortar to which C agent has been added shows a gradual increase in strength after its rise, and it can be said that it is a suitable material for the earth retaining wall construction method that penetrates the core material.

Next, the amount of solidifying material used was set to be constant at 270 kg.

The addition rate of agent C was set to 0. 0.2. 0.4. Soil mortar was prepared in the same manner as above except that the change was made at four levels of 0.6%, and its -axial compressive strength was measured. The result is the fourth
Shown in the figure. From the results shown in Figure 4, the -axial compressive strength is approximately 30 kgf101 without additives, and the C agent is at 0.2 K.
Approximately 25kgf/c with g addition! , Approximately 23kgf/ci with 0.4 kg addition, Approximately 22kf/ci with 0.6 kg addition
gf/cd and.

It can be seen that as the addition rate increases, the uniaxial compressive strength decreases exponentially, and when 0.4 kg or more is added, there is almost no decrease in strength, and the strength is about 70% of that without addition.

In this way, even if the addition amount of C agent is increased from about 0.4%, the strength decreases only slightly, and even judging from the above-mentioned penetration resistance ≠ value.

It can be said that it is desirable to add 0.4 weight i% or more to the solidifying material.

In addition, according to the present invention, since a material that originally has an anti-breathing function is used, it is advantageous in that breathing can be reduced to 0%, and the fluidity of soil mortar is also improved by consistency test. (flow cone) can satisfy the requirement of 20 seconds or less.

As explained above, the present invention is based on the anti-breathing agent used in ordinary concrete.
It was discovered that soil mortar can exhibit the effect of delaying setting while suppressing the decrease in strength, and is useful for the soil mortar earth retaining wall construction method when dealing with increases in depth and scale, as well as improving workability. exerts a very beneficial effect.

[Brief explanation of the drawings] Figure 1 is a diagram of the relationship between the addition rate of additives to soil mortar and rise time, and Figure 2 is a diagram of the relationship between the addition rate of anti-breathing agent and the unconfined compressive strength of soil mortar. It is. Figure 1 Addition rate (chi)

Claims (3)

[Claims] (1) In a soil mortar earth retaining wall construction method in which a core material is built into poured soil mortar, a soil mortar is characterized in that setting of the soil mortar is delayed by blending an anti-breathing agent into the soil mortar. Earth retaining wall construction method. (2) The soil mortar earth retaining wall construction method according to claim 1, wherein the anti-breathing agent is blended in an amount of 0.4 to 1.2% by weight based on the soil mortar solidifying agent. (3) The soil mortar retaining wall construction method according to claim 1 or 2, wherein the anti-breathing agent is a methylcellulose-based agent.