JP2004002203A - Low-strength mortar filling using shirasu - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-strength mortar filling which is a filling filled into the cavity of ground and is used instead of an air mortar filling having such a limitation that it is difficult to use an existing ready-mix concrete plant. <P>SOLUTION: The low-strength mortar filling used is a mortar prepared by mixing cement with fly ash, SHIRASU (a kind of pumiceous sand), and water. The filling contains at least 800 kg/m<SP>3</SP>SHIRASU. The mortar flow of the filling is set at 180 mm or higher. The weight ratio SH/P is at least 2.5 (wherein SH is SHIRASU, and P is the powder comprising the cement and an inorganic powder). The weight ratio FA/P is 0.7 or higher (wherein FA is the inorganic powder and P is as defined above). The weight ratio W/C is 4.0 or higher (wherein W is water, and C is the cement). <P>COPYRIGHT: (C)2004,JPO

Description

(4) The present invention relates to a low-strength mortar filler to be filled into voids, backfill, and the like in the ground.

Conventionally, when there is a cavity in the ground, a mortar filler is filled to prevent the occurrence of depression and the like, and to backfill with a backfill material after building the structure. In addition, after the mortar filler is filled and hardened, there is a possibility that excavation and foundation construction may be performed at the ground filled with mortar filler, so that there is no hindrance to excavation and foundation construction In general, low-strength air mortar is used as a mortar filler.
In air mortars, foaming agents that are not used in general mortars and concrete are indispensable. As a result, air mortar is not usually manufactured. To use air mortar, instead of using an existing ready-mixed concrete plant, it is necessary to use a dedicated mortar production plant for air mortar, or to add air bubbles in the agitator car at the site. . That is, air mortar has a complicated manufacturing process, and is not always an easy-to-use filler.

For these reasons, a low-strength mortar filler that can be easily manufactured and is inexpensive has been demanded as a substitute for air mortar.
Therefore, the present applicants can obtain a low-strength mortar filler by using `` Shirasu '', which is a volcanic deposit abundantly present in Minamikyushu, instead of fine aggregate such as sand, for mortar. The study was conducted based on the idea that this might be the case.
It has been proposed to add shirasu to concrete, which is a cement-based hardened body (for example, see Non-Patent Document 1).
Japan Concrete Institute, Japan “Concrete Engineering Annual Papers, Vol. 22, No. 2 (2000)” Published by Japan Concrete Institute, June 1, 2000

By the way, even if civil works such as excavation are performed at the production site of shirasu and a large amount of shirasu occurs, the shirasu, which is a volcanic sediment, is difficult to use effectively unlike ordinary sediment, Many of the shirasu that had been disposed of were landfilled as construction soil. Then, as shown in the above-mentioned Non-Patent Document 1, research using shirasu as fine aggregate in concrete has been conducted.
On the other hand, as described above, a low-strength material is indispensable as a filler for the hollow of the ground. For example, in an air mortar used for the above-described filling, (the compressive strength can be adjusted. )) Those having a compressive strength of 1.0 N / mm ² or less were normally used.
On the other hand, in the past, in research on cement-based cured products using shirasu as a part of fine aggregate, obtaining a low-strength cured product similar to air mortar has not been considered, and similar to air mortar. Mortar using low-strength shirasu has not been developed yet.

The object of the present invention is to use shirasu, which is a volcanic sediment, to manufacture easily, at low cost, and to fill hollows in the ground, and to have strength and fluidity suitable as a backfill material. It is to provide a low strength mortar filler.

The invention according to claim 1 is a low-strength mortar filler using shirasu to be filled in a hollow, backfill, or the like of a ground, and is composed of cement, an inorganic powder, shirasu, and water, and is used as an aggregate. Is characterized by using only Shirasu.
According to the first aspect of the invention, a low-strength mortar filler can be obtained by using a large amount of shirasu without using a foaming agent to contain a large amount of air. It can be carried out at a ready-mixed concrete plant like a mortar, and it can be easily manufactured without the need for post-addition of air bubbles at a dedicated plant or site like an air mortar.

A second aspect of the present invention is the low-strength mortar filler according to the first aspect, wherein a weight ratio W / C of the water W and the cement C is 4.0 or more.
By setting the water / cement ratio W / C to 4.0 or more, it also depends on the relationship with other compositions (for example, the weight ratio of cement C to powder P, the weight ratio of Shirasu SH to powder P). However, it is possible to reduce the strength of the mortar after curing to 1.0 N / mm ² or less.

According to a third aspect of the present invention, there is provided the low-strength mortar filler according to the first or second aspect, wherein the shirasu is contained in an amount of 800 kg / m ³ or more per unit volume.
According to the third aspect of the present invention, since the shirasu is contained in an amount of 800 kg / m ³ or more per unit volume, the bleeding rate can be reduced to 3.0% or less, and the quality of the low-strength mortar filler after hardening. Can be increased.

Further, since shirasu is contained in a large amount of 800 kg / m ³ or more per unit volume, there is no need to add other fine aggregates and the like, and basically, cement, inorganic powder, shirasu, and water are required. What is necessary is just to contain the appropriate admixture. Here, as described above, shirasu is a volcanic sediment that has not yet been effectively used, and can be obtained at a low cost. In particular, in Kyushu, where Shirasu is produced, it is available at a very low price It is.
Therefore, even if the low-strength mortar filler contains a large amount of shirasu, it can be produced at extremely low cost. In addition, since low-strength mortar filler is required to have low strength, only a small amount of cement is used, and it can be manufactured at low cost.
Furthermore, since shirasu is construction waste soil that is landfilled as described above, by using it in large quantities per unit volume, it is possible to reduce the amount of shirasu to be landfilled, which is an environmental measure as well as the cost of landfill. Can be reduced.

According to a fourth aspect of the present invention, in the low-strength mortar filler according to any one of the first to third aspects, a mortar flow when kneading cement, an inorganic powder, shirasu, and water is 180 mm or more. It is characterized by the following.
According to the invention as set forth in claim 4, the mortar flow is set to 180 mm as a fresh property of the low-strength mortar filler. Can be performed, and a gap can be prevented from being generated at the time of filling, thereby improving workability.

According to a fifth aspect of the present invention, there is provided the low-strength mortar filler according to any one of the first to fourth aspects, wherein the weight ratio SH of the shirasu SH and the powder P obtained by combining the cement and the inorganic powder is used. / P is 2.5 or more.
By setting the shirasu-powder ratio SH / P to 2.5 or more, the relationship with other compositions (for example, the weight ratio of cement C and powder P, the weight of water W and cement C or powder P) Although depending on the ratio, the mortar after curing can have a low strength of, for example, 1.0 N / mm ² or less, and the mortar flow should be 180 mm or more, and the bleeding rate should be, for example, 3% or less. Becomes possible.

According to a sixth aspect of the present invention, there is provided the low-strength mortar filler according to any one of the first to fifth aspects, wherein the weight of the inorganic powder FA and the powder P obtained by combining the cement and the inorganic powder are combined. The ratio FA / P is 0.7 or more.
By setting the inorganic powder / powder ratio FA / P to 0.7 or more, the relationship with other compositions (for example, weight ratio of Shirasu SH to powder P, water W to cement C or powder P). Although depending on the weight ratio, the mortar after curing can have a low strength of, for example, 1.0 N / mm ² or less.

According to the present invention, even if a large amount of air is not included using a foaming agent, a large amount of shirasu can be used, and a low-strength mortar filler can be obtained. It can be carried out in a ready-mixed concrete factory, and can be easily manufactured without the need for a dedicated plant or the work of post-adding air bubbles into the agitator vehicle like an air mortar.
Further, since a large amount of shirasu is contained, a low-strength mortar filler can be manufactured at low cost.

Hereinafter, the low-strength mortar filler of the embodiment of the present invention will be described in detail.
The low-strength mortar filler of this embodiment (hereinafter, sometimes abbreviated as filler) contains cement, inorganic powder, shirasu, and water. The low-strength mortar filler contains an admixture. As the low-strength mortar filler, shirasu is used as an aggregate, and only shirasu is used as an aggregate.
Portland cement can be used as the cement, but blast furnace cement, fly ash cement, or silica cement, which is a mixed cement, may be used instead of portland cement.

The inorganic powder is, for example, fly ash, but blast furnace slag fine powder, silica fume, limestone fine powder, coal ash, pozzolan and the like (coal ash and pozzolan also include fly ash) can be used. In this embodiment, the inorganic powder is, for example, a powder having an average particle diameter comparable to that of cement, and a low-strength mortar filler having a low cement content in order to obtain low strength, which is necessary in mortar. It is in a state where the powder is partially replaced, and suppresses separation of materials at the time of freshness due to a decrease in cement and an increase in bleeding rate. In addition, as the inorganic powder, basically, a material used by being mixed with Portland cement in various mixed cements is suitable.

Shirasu is a non-welded pyroclastic flow deposit of pumice flow and pumice fall widely distributed in southern Kyushu. As described above, Shirasu includes pumice flow deposits and pumice fall deposits, and most of them consist of sand (particle diameter: 2 mm to 20 μm) and silt (particle diameter: 20 μm to 2 μm). The mineral composition of Shirasu is mainly composed of volcanic glass and plagioclase, and is composed of pyroxene, quartz, magnetite and the like. The chemical composition of Shirasu is about 70% silicic acid, about 14% alumina, and about 8% alkali oxide.

As an admixture, a high-performance AE water reducing agent (SP) was used.
High-performance AE water reducer (SP) significantly reduces unit water volume without affecting consistency or significantly increases slump without affecting unit water volume, maintaining fresh performance such as slump Admixture.
Further, an AE auxiliary (AE) may be added as an admixture in addition to the high-performance AE water reducing agent (SP). The addition of an AE auxiliary and the incorporation of air have the effect of lowering the strength of the mortar and reducing the bleeding rate. However, in order to reduce the cost of the low-strength mortar filler, the AE auxiliary must not be included. Is preferred.
Note that the AE auxiliary (AE) adjusts entrained air when an AE water reducing agent is used, and is a type of AE agent.

The above-mentioned cement and fly ash (inorganic powder) are mixed with water in which an admixture is added in advance, kneaded, and further mixed with shirasu to obtain a filler. It will be filled into the cavities and cured.
Next, the composition of the filler cement, fly ash, shirasu, water, and the admixture will be described.
In this example, the composition of the low-strength mortar filler was determined on condition that the filler had the following properties (target performance).

That is, as the fresh properties of the filler before curing, the mortar flow is 180 to 220 mm, there is no material separation, the bleeding rate is 3.0% or less, and the fresh holding time is 60 minutes or more. That is. Thereby, the workability of the filler can be improved. If the mortar flow is smaller than 180 mm, the filler does not sufficiently flow into the gap in the ground at the time of filling the gap with the filler, which may cause a gap or the like. If the mortar flow is larger than 220 mm, the possibility of material separation or the like increases. If the bleeding rate is more than 3%, the quality of the filler after curing may not be sufficient.

In addition, the cured material after curing has a design reference strength (compression strength) of 1.0 N / mm ² or less, a unit volume mass of 1 t / m ³ or more, and a mass that does not float on water. Is preferred.
The filler has a weight (unit amount kg / m ³ ) of shirasu per unit volume of 800 kg / m ³ or more. That is, in the filler, the unit amount of shirasu is preferably 800 to 1200 kg / m ³ .

Here, when the unit amount of shirasu is 800 kg / m ³ or more, the bleeding rate can be made 3.0% or more, and the quality of the filler after curing can be made sufficient.
The unit amount of shirasu is preferably 1200 kg / m ³ or less in order to ensure fluidity at the time of freshness (mortar flow of 180 mm or more).
Further, when the unit amount of shirasu having a surface dry density of about 2 g / cm ³ is 800 to 1200 kg / m ³ , the unit volume mass does not become smaller than 1.0 t / m ³ .

The cement preferably has a unit weight (kg / m ³⁾ is 60~160kg / m ^3. When the unit amount of cement is less than 60 kg / m ³ , when the insufficient volume is supplemented by fly ash or shirasu, the flow value may not be 180 mm or more. Further, when the insufficient volume is supplemented by the unit water amount, there is a possibility that the bleeding rate may not be suppressed to 3% or less, and it may be difficult to use the filler as a filler. When the unit amount of cement is more than 160 kg / m ³ , the compressive strength is increased even if the unit amount of water is increased or the amount of air is increased by increasing the amount of AE aid (AE) added. Is likely to exceed 1.0 N / mm ² .

Fly ash is preferably more than cement, since the compressive strength of the filler at the time of curing becomes 1.0 N / mm ² or less. As described later, powder of fly ash FA, filiash and cement is used. Since the ratio to the body P is 0.7 (70%) or more, the unit amount of fly ash is preferably 2.3 times or more the unit amount of cement.
The high-performance AE water reducing agent as an admixture is preferably contained in an amount of about 1% or more based on the above-mentioned powder when the mortar flow is set to 180 mm or more, and is 3% or less in consideration of cost. Is preferred.
By increasing the amount of the AE auxiliary agent (AE), the porosity of the mortar can be increased and the compressive strength can be reduced. Thereby, the desired strength and porosity can be adjusted. In addition, there is also an effect of suppressing bleeding by increasing the void amount. However, considering cost, it is preferable not to add it, and even if it is added, it is preferable that it is 4% or less with respect to the powder P.

The amount of water is preferably 370 kg / m ³ or less for suppressing bleeding, and is preferably 290 kg / m ³ or more for adjusting the mortar flow to 180 mm or more. Also, more preferably, the unit water amount is about 360 kg / m ³ .
In addition, the properties of the low-strength mortar filler are not determined by the unit amount of each component, but are determined by the mutual relationship of each component, and each composition is preferably blended in the following ratio.

That is, the water / cement ratio W / C (%) of the water W and the cement C is preferably 400% (W / C is 4.0) or more (the cement water ratio C / W is 0.25 or less). . When the AE auxiliary agent (AE) is not used, the water / cement ratio W / C (%) is preferably 450% or more (the cement water ratio C / W is 0.22 or less). As described above, by setting the water cement ratio W / C (%) to 400% or more, the filler at the time of curing can have a low compressive strength of 1.0 N / mm ² or less. Further, when the AE auxiliary agent is not contained, it is more preferable that the water / cement ratio W / C (%) is 500% or more (the cement water ratio C / W is 0.2 or less).
However, when the water / cement ratio W / C (%) is increased, the possibility that the bleeding rate exceeds 3% increases. When the bleeding ratio is high and the compressive strength is high, for example, the target performance of bleeding and compressive strength is satisfied by increasing the water cement ratio and adding an AE auxiliary (AE). It becomes possible.

The water powder ratio W / P (%) of the water W and the powder P obtained by combining the cement and the fly ash is 100% (W / P is 1 or more) when the mortar flow is 180 mm or more. It is preferable that it is above.
Further, the fly ash powder ratio (fly ash replacement ratio) FA / P (%) between the fly ash FA and the powder P is such that the compression strength is as low as 1.0 N / mm ² or less. It is preferably at least 70%.

In other words, in order to lower the compressive strength, it is necessary to increase the water-cement ratio and reduce the unit amount of cement.However, in order to reduce the unit amount of cement, when the amount of water increases, the bleeding rate increases. Would. Therefore, it is preferable to increase the amount of fly ash by an amount corresponding to the reduction in the unit amount of cement. As described above, the fly ash replacement ratio FA / P (%) is preferably 70% or more.

Further, the shirasu powder ratio SH / P (%) between the shirasu SH and the powder P is preferably 3.5 or less in order to make the mortar flow 180 mm or more, and the compressive strength is 1 or less. In order to set the bleeding rate to 3% or less and 0.0N / mm ² or less, it is preferable to be 2.5 or more. More preferably, the shirasu powder ratio SH / P (%) is preferably about 3.

In this embodiment, shirasu is used as the low-strength mortar filler, and as described above, the filler has a mortar flow of 180 mm to 220 mm as a fresh property, no material separation, and a bleeding rate of 3.0% or less. That the fresh holding time is 60 minutes or more, the design standard strength (compression strength) is 1.0 N / mm ² or less as the curable property, and the unit volume mass is 1 t / m ³ or more ( As a target performance), an experiment was performed from Series 1 to Series 3 to determine a composition ratio satisfying these conditions.
Then, the composition of the filler as an example of the present invention was determined based on the knowledge obtained in the experiments of series 1 to series 3, and the experiment of series 4 was performed based on this composition. Therefore, the experiments of series 4 are examples of the present invention.

　なお、シラスの粒度分布は、細骨材のＪＩＳ規格の粒度分布範囲と比較した場合に、０．３ｍｍ以下の分布がＪＩＳ規格の粒度分布範囲より多く、０．１５ｍｍ以下のものがＪＩＳ規格の粒度分布範囲の上限の２倍以上となる３０％程度と多量に含まれていた。 Table 1 shows the filling materials used in this example.

In addition, as for the grain size distribution of shirasu, when compared with the grain size distribution range of the JIS standard of fine aggregate, the distribution of 0.3 mm or less is larger than the grain size distribution range of the JIS standard, and those of 0.15 mm or less are those of the JIS standard. It was contained in a large amount of about 30%, which is twice or more the upper limit of the particle size distribution range.

The mortar was kneaded using a mortar mixer (nominal capacity: 20 liters) in accordance with JIS R5201 as follows.
That is, first, cement, filli ash, and water (to which the admixture has been added) are kneaded and mixed for 30 seconds. Then, shirasu is added and kneaded for 60 seconds. After the mortar was scraped off and kneaded again for 60 seconds, the completed filler was discharged from the mortar mixer.

　なお、試験体となる充填材の養生は、所定の材齢まで型枠を残置したまま気中養生とした。 Table 2 shows test items and test methods for the manufactured filler.

In addition, the curing of the filler used as the test body was aerial curing while the mold was left until a predetermined age.

As a series 1 of experimental examples, experiments were performed in the experimental cases 1-1 to 1-9 shown in Table 4 with the factors and levels of the experiments shown in Table 3.
Table 5 shows the experimental results.

The following findings were obtained from the experimental results of Series 1.
Regarding the mortar flow of the filler, if the water powder ratio W / P was the same, no change was observed in the mortar flow even if the fly ash powder ratio (fly ash replacement ratio) FA / P changed. There was a tendency for the mortar flow to increase as the unit amount of water increased, and the degree was about 50 mm increase / decrease in the mortar flow per 20 kg / m ³ change in the unit amount of water.

Regarding the amount of air in the filler, the viscosity of the mortar was increased as the water powder ratio was reduced and the fly ash replacement ratio FA / P was decreased, and air was likely to be entrained.
Regarding the bleeding rate of the filler, the bleeding rate increased linearly as the unit amount of water increased, and the bleeding rate tended to increase or decrease by approximately 0.5% per change in the unit amount of water of 10 kg / m ³ . .

Regarding the compressive strength of the filler, the compressive strength tended to decrease as the fly ash replacement ratio FA / P increased and as the water-cement ratio W / C increased.
In particular, there is a high correlation between the water cement ratio W / C and the compressive strength, and the compressive strengths fc7 and fc28 between the age of 7 days and the age of 28 days can be expressed by the following linear expressions. Was.
fc7 = 7.4C / W-1.9
fc28 = 11.1C / W-1.2
That is, at a material age of 28 days, the compressive strength tended to increase and decrease by 1.1 N / mm ² per cement water ratio C / W of 0.1, which is the reciprocal of the water cement ratio W / C.

で は In the unit volume mass of the filler, when the water powder ratio W / P was the same, the fly ash replacement ratio FA / P became smaller as the ratio became larger.

As a series 2 of experimental examples, experiments were performed in experimental cases 2-1 to 2-7 shown in Table 7 with the factors and levels of the experiments shown in Table 6. In the series 2, the water powder ratio W / P and the fly ash powder ratio FA / P were examined together with the change in the properties of the filler due to the difference in the amount of air.
Table 8 shows the experimental results.

The following findings were obtained from the experimental results of Series 2.
As for the mortar flow of the filler, the mortar flow increased as the water powder ratio W / P increased, and the amount of air mixed in decreased as described later. However, when the water powder ratio W / P (%) is 110%, the value of the mortar flow is in the range of 140 to 170 mm even when the amount of air changes, and the difference in the amount of air affects the fluidity. I did not see much. From this, it is considered that the factor that affects the fluidity is the water powder ratio W / P, and it is considered that the air entrainment decreases as the fluidity increases. Therefore, it was considered that the effect of changing the air amount with the AE auxiliary (AE) was small.

Regarding the amount of air in the filler, no effect of the water powder ratio on the amount of air was observed in the case where the AE auxiliary (AE) was not added, but the AE auxiliary (AE) was added to the powder to P in an amount of 1. In the case where 0% was added, the air amount decreased as the water powder ratio increased. That is, as described above, it is considered that a decrease in the amount of air is observed due to a decrease in air entrainment due to an increase in the fluidity of the mortar.
In addition, even when there was no AE auxiliary agent (AE) and when the AE auxiliary agent (AE) was 1%, the fly ash replacement ratio FA / P had almost no effect on the air amount.
The bleeding rate tended to decrease as the amount of air increased.
Thus, it was found that bleeding can be suppressed by mixing air.

Regarding the compressive strength of the filler, the compressive strength tended to decrease as the water powder ratio W / P and the fly ash replacement ratio FA / P increased, and as the amount of air increased.
Here, the cement void ratio c / v can be determined by the following equation.
c / v = Vc / (Vw + Vair)
Vc: unit volume of cement, Vw: unit volume of water, Vair: unit volume of air

The cement void ratio has a high correlation with the compressive strength at both the ages of 7 and 28 days. At the age of 28, the compressive strength increases and decreases by 0.27 N / mm ² per the cement void ratio of 0.01.
From this, it is considered that the cement void ratio and the compressive strength (compressive strength fc28 on the age of 28) can be expressed by the following linear expression, and the compressive strength can be estimated from the cement void ratio. Further, the compressive strength fc7 of the material age 7 can also be expressed by the following equation.
fc28 = 27.3c / v-1.1
fc7 = 20.7c / v-1.0

As a series 3 of experimental examples, experiments were performed in experimental cases 3-1 to 3-4 shown in Table 10 with the factors and levels of the experiment shown in Table 9. That is, the purpose was to confirm the influence on fluidity, bleeding and compressive strength by changing the shirasu powder ratio SH / P by four levels.
Table 11 shows the experimental results.

The following findings were obtained from the experimental results of Series 3.
As for the mortar flow of the filler, the flowability decreased as the shirasu powder ratio SH / P increased. From this, it is considered that a shirasu powder ratio of 3.5 or less is desirable in order to set the mortar flow to 180 mm or more on the assumption that a high-performance AE water reducing agent (SP) is used in an appropriate amount.

The air amount of the filler is about 5% up to the shirasu powder ratio SH / P2.5, but as the shirasu powder ratio increases, more air is mixed in. This is considered to be due to the fact that the fluidity was reduced with an increase in the shirasu powder ratio SH / P, so that air was easily entrained.
As for the bleeding rate of the filler, the result became larger as the shirasu powder ratio SH / P was smaller (in this experiment, the unit water amount was larger). In order to satisfy the target performance of bleeding rate of 3.0% or less, it was considered that the shirasu powder ratio was desirably 2.5% or more. In addition, in this experiment, as shown in Table 10, when the shirasu powder ratio was 2.5%, the unit amount of Shirasu SH was 784 kg / m ³ , and when the bleeding ratio was set to 3.0% or less, And the unit amount of Shirasu SH is preferably 800 kg / m ³ or more.

With respect to the compressive strength of the filler, the higher the Shirasu powder ratio SH / P, the lower the compressive strength. This was considered to be due to the fact that the air amount increased as the shirasu powder ratio SH / P increased, resulting in a decrease in compressive strength.
The cement void ratio described above has a high correlation with the compressive strength at both the ages of 7 and 28 days. At the age of 28 days, the compressive strength per 0.01 of the cement void ratio increases and decreases by about 0.35 N / mm ² . From this, it is considered that the compressive strength can be estimated by a linear expression of the cement void ratio and the compressive strength.
fc7 = 35.3c / v-1.8
fc28 = 26.3c / v-1.4

With respect to the unit volume mass of the filler, when the Shirasu powder ratio was 2.5 or more, the unit volume mass decreased almost linearly. This is considered to be due to the fact that as the shirasu powder ratio SH / P increases, the fluidity decreases, more air is mixed in, and the unit volume mass decreases.

In Experiment Series 4, based on the results of Series 1 to Series 3 so far, the following two types of optimal formulations were extracted as the formulations satisfying the above-mentioned target performance.
That is, (1) when the set amount of air is set to 0% without using the AE assistant (AE), and (2) when the AE assistant (AE) is used and air is mixed.
(1) When AE Auxiliary (AE) is not Used From the results of series 1 to 3 described above, the following conditions were determined as experimental conditions for satisfying the target performance.
1) Cement water ratio: Based on the result of compressive strength, the ratio is set to 0.22 or less (450% or more when the water cement ratio (%) is set).
2) Unit amount of water: According to the result of bleeding, it is set to 360 kg / m ³ or less.
3) FA replacement ratio FA / P (%): From the results of the compressive strength test, it is set to 70% or more.
4) Shirasu powder ratio: set to about 3.0 from the result of series 3.
The above conditions do not limit the present invention, but are conditions that are presumed to be more preferable.
(2) When AE Auxiliary (AE) is Used From the results of Series 1 to 3, in Experiment Case 2-7 of Series 2, although the mortar flow is slightly low, the result that generally satisfies the required performance is obtained. It was decided to consider a formulation that reduced the material cost by the following method. That is, the experiment was performed by changing the conditions of the experimental case 2-7 as follows.
1) Reduction of AE auxiliary agent (AE) addition amount: The set air amount is changed from 15% to 10%, and the AE auxiliary agent (AE) addition amount is reduced.
2) Water cement ratio W / C (%): From 365% to 400% in order to reduce strength.
3) Fly ash replacement ratio FA / P (%): 70% to 72.5% in order to reduce strength.
In the case (2), the amount of the AE auxiliary agent (AE) is reduced for cost reduction in the experimental case 2-7. The increase in the strength of the material was suppressed by increasing the water cement ratio W / C and increasing the fly ash replacement ratio FA / P.

In the experiment series 4, based on the above conditions, experiments were performed in the experimental cases 4-1 to 4-3 shown in Table 12. With respect to the mortar flow, the amount of air, and the mass per unit volume, changes over time of 0 minute, 30 minutes, and 60 minutes after kneading of the filler were measured.
Table 13 shows the experimental results.

わ か る It can be seen that the mortar flow of the filler satisfies the target mortar flow of 180 mm to 220 mm at the set holding time of 60 minutes even when the AE auxiliary agent (AE) is not used and when it is used. From this result, it is considered that the fluidity sufficiently satisfies the target performance in any case within the holding time of 60 minutes or less. In addition, in consideration of economic efficiency, it is considered that a composition in which an AE auxiliary (AE) is not added is desirable.

The air amount of the filler is approximately 2% in each of the experimental cases after a lapse of 60 minutes, and it is considered that the influence of the air amount over time on other properties is small.
Regarding the bleeding rate of the filler, the results sufficiently satisfied the target performance of 3.0% or less in each case. In addition, it was shown that bleeding could be suppressed by reducing the water-cement ratio.
Regarding the unit volume mass of the filler, an increase was observed due to a change with time. This is considered to be due to the increase in unit volume mass due to a 2% decrease in the amount of air in 60 minutes.
Regarding the compressive strength of the filler, the one where the water cement ratio W / C (%) was set to 450 without adding the AE auxiliary slightly exceeded the target performance of 1.0 N / mm ² . This is because the strength can be reduced by lowering the cement porosity ratio by, for example, increasing the shirasu powder ratio SH / P or adding an AE auxiliary agent.

From the above, the mortar flow of the filler is affected by the water cement ratio, the fly ash replacement ratio (fly ash powder ratio), etc., but can be adjusted by the high-performance AE water reducing agent. It is possible to satisfy a flow of 180 mm to 220 mm and a fresh property holding time of 60 minutes.
In addition, the bleeding rate of the filler can be reduced to 3.0% or less by setting the unit water amount to 370 kg / m ³ or less, further reducing the water-cement ratio, and increasing the air amount by adding an AE auxiliary agent. It is.

The compressive strength can be estimated from the water-cement ratio (cement-water ratio). By setting the cement-water ratio C / W to 0.2 or less (water-cement ratio W / C (%) to 500% or more), the target performance 1 0.0N / m ² or less. If the target performance of the bleeding ratio cannot be satisfied at a cement water ratio C / W of 0.2 or less, for example, the upper limit of the cement water ratio C / W is set to 0.25 (the lower limit of the water cement ratio W / C is set to 400%). ), And increasing the amount of air with the AE auxiliary agent, it is possible to achieve the target performance of both the bleeding rate and the compressive strength.
The unit mass per unit achieved the target performance of 1.0 t / m ³ or more in each of the experimental cases, and can be achieved under the above-described conditions.

From the above results, it is considered that the conditions of the experimental case 4-2 are most suitable in this experiment.
Actually, it is considered that the best conditions are different depending on the difference in physical property values of the materials used in the field, the type of the inorganic powder, and the like. Unit quantities need to be determined.

Claims (6)

It is a low-strength mortar filler using shirasu to be filled into the hollows of the ground, backfilling, etc.
A low-strength mortar filler using shirasu, which is composed of cement, inorganic powder, shirasu, and water, and uses only shirasu as an aggregate. The low-strength mortar filler using shirasu according to claim 1, wherein the weight ratio W / C of the water W and the cement C is 4.0 or more. Low intensity mortar filler with Shirasu according to claim 1 or 2, characterized in that Silas contained 800 Kg / m ³ or more per unit volume. The low-strength mortar filler using shirasu according to any one of claims 1 to 3, wherein the mortar flow when kneading cement, inorganic powder, shirasu, and water is 180 mm or more. The shirasu according to any one of claims 1 to 4, wherein a weight ratio SH / P of the shirasu SH and the powder P obtained by combining the cement and the inorganic powder is 2.5 or more. Low strength mortar filler used. The weight ratio FA / P of the inorganic powder FA and the powder P obtained by combining the cement and the inorganic powder is not less than 0.7, according to any one of claims 1 to 5, wherein Low strength mortar filler using Shirasu.