JP2002307421A - Method for manufacture of light weighted cement-based filler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid complication of construction equipment and complication of construction control. SOLUTION: In a manufacturing method, components are constituted of cement C bentnite B water W and foamed styrene bead HB, and those components are mixed by a series of systems to manufacture a light weighted cement based filler G. At first the bentnite B and the water W are cast into a stirring tank T1 and bentnite slurry BS is prepared by mixing them by stirring. By allowing the prepared bentnite slurry BS to stand still for a specific time, sufficient swelling of the bentnite B in the slurry B is achieved. Besides, mortar M is prepared by casting the cement C and the water W into another stirring tank T2 to be mixed by stirring. The bentnite slurry BS is added to the prepared mortar M. They are mixed by stirring. Besides the foamed styrene bead HB is cast into the mixture, which is further mixed by stirring to manufacture the light weighted cement based-filler G.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a lightweight cement-based filler, and more particularly to a method for producing a lightweight cement-based filler used for backfilling a backside of a retaining wall or backfilling a tunnel lining. It relates to a manufacturing method.

[0002]

2. Description of the Related Art As a lightweight filler to be backfilled on the back side of a structure such as a retaining wall, a cement-based air mortar in which air bubbles are mixed into a mortar has the best results. However,
Such an air mortar has the following problems.

[0003] First, in the air mortar, since the difference in specific gravity between the air bubbles and the mortar is very large, separation of the material easily occurs when vibration or pressure is applied or with the passage of time, and the volume decreases. .

[0004] When bubbles come into contact with water, the bubbles disappear and the volume is reduced, and special machines such as a foaming machine and a bubble mixer are required. To cope with such a problem, for example, Japanese Patent Application Laid-Open No. 2000-282036 proposes a cement-based filler in which expanded styrene beads are mixed instead of air bubbles.

[0005] The cement-based filler proposed in this publication is formed by mixing and stirring cement milk or cement air milk in which air bubbles are mixed with cement milk, and bentonite milk. Foamed styrene beads for specific gravity adjustment are mixed therein.

[0006] According to the cement-based filler configured as described above, by replacing cells with expanded styrene beads,
Problems such as material separation and volume reduction are eliminated. However, such a conventional method for producing a cement-based filler has the following technical problems.

[0007]

That is, the cement filler proposed in the above publication is a mixture of cement and water, or cement milk in which cement, water and air bubbles are mixed, and bentonite and water. The pumped-in bentonite milk is pumped, and these are stirred and mixed at the tip to produce a filler, so that two mechanical systems are required.

In order to obtain a cement-based filler having a predetermined blending ratio in which a predetermined amount of expanded styrene beads are mixed, flow meters must be installed in at least two systems.
In addition to the complexity of the construction equipment, there was a problem that the construction management became complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has as its object to reduce the weight of the construction equipment and the complexity of construction management. It is an object of the present invention to provide a method for producing a cementitious filler.

[0010]

In order to achieve the above object, the present invention relates to a method for producing a lightweight cement-based filler used for backfilling the backside of a retaining wall or backfilling a tunnel lining. The cement-based filler was composed of cement, bentonite, water, and expanded styrene beads, and these constituent materials were mixed in a series.

According to the method for producing a lightweight cement-based filler thus constructed, expanded styrene beads are mixed with the cement-based filler. The expanded styrene beads are, for example, 80-fold expanded and have a specific gravity of 0.1. Since the specific gravity is as very small as about 0125, the weight of the filler can be reduced according to the amount of the foamed styrene beads mixed, and hardly hardly causes a volume decrease.

In this case, the expanded styrene beads have almost no water absorption, so that when added to the filler, they do not affect the water-cement ratio or the water content for swelling of bentonite.
Filler composition design can be performed easily.

Further, in the present invention, the cement-based filler is composed of cement, bentonite, water, and expanded styrene beads, and these constituent materials are mixed in a series of systems. Only one flow meter is required, and it is possible to avoid complication of construction equipment and complicated construction management.

In this case, the production of the cement-based filler is as follows:
No special machinery is required.

In the present invention, it is desirable that the bentonite to be mixed with the cement filler is mixed with water and stirred to prepare a bentonite slurry before kneading with the cement to sufficiently swell the bentonite.

By adopting such a configuration, the unit water amount can be increased with a small amount of bentonite, whereby the weight of the cement filler can be reduced.

The reason is based on the following mechanism.

That is, bentonite, which is a water-swellable substance, and water are mixed and stirred to produce a bentonite slurry, and the produced bentonite slurry is kneaded with mortar. As a result, calcium ions generated by hydration of hydraulic cement are removed. Since it is not present when swelling bentonite, calcium ions do not affect the swelling action of bentonite at all, and can be sufficiently swelled.

Therefore, even with a small amount of bentonite, the viscosity of the cement-based filler can be sufficiently increased, and when the viscosity of the cement-based filler is increased, the buoyancy acting on the expanded styrene beads is reduced. In addition to mixing and stirring easily, the gelling action of bentonite prevents the foamed styrene beads from separating due to an increase in viscosity.

The expanded styrene beads have a diameter of about 2 m.
m.

Foamed styrene beads having a very small specific gravity cause material separation due to a difference in specific gravity from cement when vibration is applied, and the specific gravity is as small as possible in consideration of buoyancy during mixing. However, in the case of the present invention, since the viscosity is increased by adding bentonite to the cement-based filler, such a problem does not occur even with a diameter of about 2 mm.

The expanded styrene beads can be added in an amount of 20 to 30% per unit volume of the cement-based filler.

The weight of the cement filler is reduced by an amount corresponding to the amount of the expanded styrene beads having a very small specific gravity. However, if the content is 20% or less, the degree of weight reduction becomes insufficient.

On the other hand, when expanded styrene beads are added,
Although the strength is reduced, the addition amount of 30% or less does not cause the practically problematic reduction in strength.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG.
Shows an embodiment of a method for producing a lightweight cement-based filler according to the present invention.

In the manufacturing method shown in FIG.
It is composed of bentonite B, water W, and expanded styrene beads HB, and these constituent materials are mixed in a series to produce a lightweight cement-based filler G.

In this embodiment, in this case, first, FIG.
As shown in (A), bentonite B and water M are charged into a stirring tank T1, and these are stirred and mixed to produce a bentonite slurry BS.

The produced bentonite slurry BS is
By allowing the slurry to stand for a predetermined time, the bentonite B in the slurry S can be sufficiently swollen. On the other hand, FIG.
As shown in (2), a cement C and water W are put into another stirring tank T2, and the mortar M is produced by stirring and mixing these.

The prepared mortar M has a bentonite slurry BS in which bentonite B has been sufficiently swollen.
Is added, and the mixture is stirred and mixed. The foamed styrene beads HB are put into the mixture, and the mixture is further stirred and mixed to produce the lightweight cement-based filler G.

In the manufacturing process of the filler G shown in FIG. 1, the expanded styrene beads HB may be previously mixed and stirred with the mortar M before mixing the bentonite slurry BS with the mortar M.

The following Table 1 shows that the two compounding ratios (Examples 1 and 2) of the lightweight cement-based filler G produced in the above-described steps are comparative examples in the case where the expanded styrene beads HB are not added. It is shown with

In the compounding ratio shown in this table, blast furnace cement B is used as cement C, and foamed styrene beads HB having 80 times expansion ratio, specific gravity of 0.0125 and diameter of about 2 mm are used. Was. The admixture is Geolitter 10
(Manufactured by Nippon Paper) and added for retarding curing.

Example 1 is an example in which expanded styrene beads HB corresponding to 20% per unit volume of the cement-based filler G are added.
Of foamed styrene beads HB corresponding to 30% per unit volume of.

[0034]

【table】

As is clear from the results shown in Table 1, in Example 1,
The specific gravity of the obtained filler G was 0.99, and in Example 2, the specific gravity was 0.87, which was considerably lighter than the comparative example.

Further, the mortar flow values were measured in Examples 1 and 2.
And Comparative Example have almost the same value. Further, when each filler G is cured, the uniaxial compressive strength σ after 7 days of material age
7, the values of Examples 1 and 2 were almost the same as those of the comparative example. However, the uniaxial compressive strength σ28 after 28 days of the material age was about 5% of that of the comparative example. In No. 2, a decrease of about 10% was observed, but such a decrease in strength was not enough to cause a practical problem.

From the test results shown in the above table, it can be seen that it is preferable to add 20 to 30% of expanded styrene beads HB per unit volume of the cement filler G. That is, the cement filler G is reduced in weight by an amount corresponding to the amount of the expanded styrene beads HB having a very small specific gravity, but if it is 20% or less, the degree of weight reduction becomes insufficient.

On the other hand, when foamed styrene beads HB are added, the uniaxial compressive strength σ28 after 28 days of material age decreases,
If the addition amount is less than 30%, the strength does not decrease so much as to hinder practical use.
Is 20 to 30 per unit volume of the cement-based filler G.
% Is desirably added.

According to the manufacturing method of the lightweight cement-based filler G configured as described above, the expanded styrene beads HB are mixed with the cement-based filler G. Double foaming, specific gravity 0.0
Since the specific gravity is very small at about 125, the weight of the filler can be reduced according to the amount of the foamed styrene beads HB mixed.

In this case, since the water absorption of the expanded styrene beads HB is almost zero, there is no influence on the water-cement ratio of the cement filler G or the amount of water for swelling of the bentonite B, and the blending design can be easily performed. .

In this embodiment, the cement-based filler G
Is composed of cement C, bentonite B, water W, expanded styrene beads HB, and these constituent materials are mixed in a series of systems, so that there is no need for multiple construction systems, and only one flow meter is required. It is possible to avoid complicated equipment and complicated construction management.

In this case, no special machine is required for producing the cement filler G.

In this embodiment, the cement-based filler G
Is mixed with water W and mixed with water C before mixing with cement C.
And bentonite B is sufficiently swelled.

By adopting such a configuration, the unit water amount can be increased with a small amount of bentonite, whereby the weight of the cement filler G can be further reduced.

The reason is that bentonite B and water W are first mixed and stirred to produce a bentonite slurry BS, and the bentonite B in a slurry state is kneaded with mortar.
Since calcium ions generated by hydration of hydraulic cement do not exist when swelling bentonite B,
This is because calcium ions do not affect the swelling action of bentonite B and can sufficiently swell.

When the bentonite B is sufficiently swelled,
Even with a small amount of bentonite, the viscosity of the cement-based filler G can be sufficiently increased, and when the viscosity of the cement-based filler G is increased, the viscosity increases and the expanded styrene beads HB
Can be effectively prevented from being separated.

FIG. 2 shows an example of the use of the lightweight cement-based filler G of the present embodiment. In this example of use, the filler G is employed for backfilling a tunnel lining. FIG.
FIG. 2 is a cross-sectional view of the tunnel. In the tunnel, a segment 1 is assembled in an annular shape along an excavation surface, and a secondary lining 2 is installed inside the segment.

The secondary lining 2 is a hollow cylindrical synthetic resin tube 3.
And a backfill layer 4. A synthetic resin pipe 3 is installed inside the segment 1 at a predetermined interval.
The backfill layer 4 is formed by filling the lightweight cement-based filler G according to the present invention between the backfill layer 4 and the synthetic surgical tube 3.

When the lightweight cement-based filler G is used for the backfill layer 4 of the secondary lining 2 of the tunnel configured as described above, the construction can be easily performed, and the load applied to the synthetic resin pipe 3 can be reduced. be able to.

FIG. 3 shows another example of the use of the lightweight cement-based filler G of the present embodiment. In this example of use, the filler G is used for backfilling the upper floor and side walls of the overpass. Has been adopted.

In the overpass shown in the figure, a road is provided below the erected upper floor portion 5, and both ends of the upper floor portion 5 are supported by side wall portions 6.

The upper floor portion 5 and the side wall portion 6 have a structure in which a plurality of elements 8 are connected as shown in detail in FIG. Each element 8 has a steel plate 9
And a backing material 10. The space having a rectangular cross section is separated by the steel plate 9, and the space-saving material is filled with the lightweight cement-based filler G of the present embodiment and hardened to form the backing material 10. ing.

The space between the elements 8 installed adjacent to the side is
They are connected by fluidized concrete 11. When the lightweight cement-based filler G is used for such an element 8, the weight of the upper floor portion 5 and the side wall portion 6 can be reduced.

FIG. 4 shows another example of the use of the lightweight cement-based filler G of the present embodiment. In this example, the filler G is applied to the backfill soil filled on the back surface of the retaining wall. Has been adopted.

In the example of use shown in the same figure, a retaining wall 12 is constructed near a house, and backfilled soil 13 is filled on the back side thereof to widen the pavement road 14. The lightweight cement-based filler G of the present embodiment is employed.

When the lightweight cement-based filler G is used for such backfill soil 13, since the weight is light, the lateral pressure on the retaining wall 12 is reduced, and at the same time, the retaining wall 12 is self-supported and the safety of construction is increased.

FIG. 5 shows still another example of the use of the lightweight cement-based filler G of this embodiment. In this example, the filler G is applied to the backfill soil filled on the back surface of the retaining wall. Has been adopted.

In the example of use shown in the figure, a retaining wall 15 is constructed on a steep slope, a slip resistance pile 16 is cast on the slope, and the back side of the retaining wall 15 is filled with backfill soil 17. A pavement road 18 is formed at the top, and as backfill soil 17,
The lightweight cement-based filler G of this embodiment is employed.

The same effect as in the use example shown in FIG. 4 can be obtained even when the lightweight cement-based filler G is used for the backfill soil 17 in such a place.

In the above embodiment, the bentonite B and the water W are mixed first to prepare a bentonite slurry BS, which is added to and mixed with the mortar Mi. However, the practice of the present invention is as follows. However, the present invention is not limited to this, and the filler G can be manufactured by mixing them at the same time.

[0060]

As described above in detail, according to the method for producing a lightweight cement-based filler according to the present invention, it is possible to avoid complicated construction equipment and complicated construction management.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a production process showing one embodiment of a method for producing a lightweight cement-based filler according to the present invention.

FIG. 2 is an explanatory view of a usage example of a lightweight cement-based filler produced by the production method of the present invention.

FIG. 3 is an explanatory view of an example of use of a lightweight cement-based filler produced by the production method of the present invention.

FIG. 4 is an explanatory diagram of an example of use of a lightweight cement-based filler produced by the production method of the present invention.

FIG. 5 is an explanatory diagram of an example of use of a lightweight cement-based filler produced by the production method of the present invention.

[Explanation of symbols]

 C Cement B Bentonite W Water HB Expanded styrene beads BS Bentonite slurry M Mortar

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) C04B 16:08) (72) Inventor Yoshiaki Uegaki 2-15-2 Konan, Minato-ku, Tokyo Obayashi-gumi Tokyo Co., Ltd. Head office F-term (reference) 2D055 JA00 KA00 4G012 PA06 PA23 PE01 4G056 AA07 CB25

Claims (4)

[Claims] 1. A method for producing a lightweight cement-based filler used for backfilling a backside of a retaining wall, backfilling a tunnel lining, etc., wherein the cement-based filler is cement, bentonite, water,
A method for producing a lightweight cement-based filler, comprising foamed styrene beads, and mixing these constituent materials in a series. 2. The weight reduction according to claim 1, wherein the bentonite is mixed with water and stirred to produce a bentonite slurry before kneading with the cement to sufficiently swell the bentonite. Manufacturing method of cement-based filler. 3. The expanded styrene beads have a diameter of about 2
The method for producing a lightweight cement-based filler according to claim 1, wherein the filler is formed in a size of mm. 4. The lightweight cement-based filler according to any one of claims 1 to 3, wherein the expanded styrene beads are added in an amount of 20 to 30% per unit volume of the cement-based filler. Manufacturing method.