JPH0689539B2 - Solidified reinforced structure and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a solidified reinforced structure for protecting and stabilizing a portion where the ground surface comes into contact with surface water, particularly, a molding in a mold bag made of a water-permeable sheet. The present invention relates to a solidified surface-reinforcing structure and a manufacturing method thereof.

(Prior art) Conventionally, high strength flexible perforated bags, such as synthetic fibers, for application to revetments for rivers, canals, waterways, lakes, dams, reservoirs, harbors, slope protection, scouring prevention, etc. Covering the ground surface with a reinforcing structure made by casting and hardening cement concrete in a mold bag made of cloth is known, for example
It is known from 46-25345 and Japanese Utility Model Publication No. 54-32804, and is widely put into practical use. However, such a known construction method not only requires a large amount of cement, but especially when applied to lakes and dams in steep mountain areas, the transportation cost is enormous and time constraints and It is often impossible to use a mixer truck that requires road maintenance.

On the other hand, conventionally constructed dams and reservoirs have sludge, that is, sludge consisting of dead plants accumulated on the bottom of the water for a long period of time, organic substances including animal carcasses or eroded / weathered crustal inorganic substances, that is, drought. If the water level drops during the period or due to an increase in water intake, sludge floats and hangs, resulting in severe pollution of water quality, which may interfere with mechanical devices such as power plants that use this water or increase the load on water purification facilities. It causes inconvenience such as coming. Therefore, the amount of water taken is naturally limited to only the supernatant,
The capacity that can be taken in is significantly smaller than the storage capacity. Dredging of sludge is carried out for the purpose of eliminating such inconveniences and increasing the amount of water intake. Currently, they are enthusiastic about measures and disposal such as burial. A similar phenomenon is seen in industrial waste such as fly ash generated from pulverized coal boilers, which has increased since the oil shock, and the treatment thereof has become a serious problem newly facing power plants and the like.

(Problems to be Solved by the Invention) The present invention has been made in order to solve various problems incidental to the above-described prior art, and its main purpose is to:
It is an object of the present invention to provide a solidified reinforced structure which is coated / constructed at a contact interface between the ground surface and surface water such as a water bottom surface and a slope by an inexpensive and easy method.

Another important purpose is to effectively utilize industrial waste such as sludge or fly ash and prevent weathering, erosion, scouring and surface water pollution of the ground surface, thus contributing to environmental protection.

Another purpose is that there is no pollution due to sludge floating and suspension,
It is planned to construct a dam or a reservoir with a large intake capacity easily even in a remote mountain area where transportation is inconvenient.

(Means for Solving Problems) The above-mentioned object is to provide a fine hydrated particulate solid content derived from sludge or industrial waste and an inorganic hydrate matrix containing ettringite phase as a main component in a mold bag made of a water-permeable sheet. Is achieved by being mixed and filled and densely solidified and molded.

The above-mentioned structure of the present invention has a 28-day strength after solidification molding of preferably at least 250 ton / m ² in uniaxial compression strength.

Further, in constructing a solidified reinforced structure that covers and protects and stabilizes the ground surface that comes into contact with surface water, the method of the present invention is a method in which a concentrated sludge of sludge dredged from the water bottom or an aqueous sludge of fine industrial waste is used. It is characterized in that a solidifying material is added to and mixed with, and this is injected and filled into a mold bag which has been previously spread on the construction surface to be solidified.

The most preferred solidifying material is at least 10% by weight of 3CaO.Al ₂ O ₃ component and at least about 20% by weight of CaSO ₄
・ Contains 2H ₂ O component and the balance is 3CaO ・ SiO ₂ and 2Ca
It is a calcium silicate-based hydraulic composition mainly composed of O · SiO ₂ .

Further, in the above-mentioned method of the present invention, the sludge preferably contains about 100 to 150% of water based on the weight of the solid content, and the solidifying agent is preferably added at a rate of about 200 to 350 kg per 1 m ³ of the sludge.

Here, the ground surface that comes into contact with the surface water includes the surface water, that is, the bottom surface and slopes that are in constant contact with the water existing on the surface such as rivers, lakes, dams, reservoirs, harbors and coasts. It includes the ground surface and the ground surface that may be eroded or scourd due to abnormal flooding such as rainfall and snowmelt, flooding.

Hereinafter, the method of the present invention will be described in more detail with reference to the accompanying drawings in the case where the starting material is sludge or sludge.

The figure is a schematic explanatory view showing a specific example of the steps in the method of the present invention.

In the method of the present invention, basically, the first step ... sludge dredging second step ... sludge concentration third step ... solidifying material mixing fourth step ... mold injection, fifth step ... solidification molding are sequentially carried out in the above order. It depends on.

In the figure, the first step is the river, lake, pond, dam,
The sludge 1 deposited on the bottom of the water such as a harbor is dredged by a well-known and conventional means such as a dredging ship, a water sand removal robot, a vacuum pump, and a clam shell. The figure shows an example of use of the underwater sand removal robot 2. The dredged sludge is usually passed through an automatic sieve, preferably a multi-stage sieve 3 to a sediment layer 4 while sieving gravel-like substances, coarse dust and the like and performing a second step.

In the second step, for example, in the settling layer 4 consisting of a cylindrical tank equipped with a horizontal rotary stirrer 5 at the center, the stirrer 5 is mechanically coagulated and precipitated while slowly rotating the stirrer 5, and the concentrated sludge is sequentially taken out to remove excess water. To release. It is also possible to mix an appropriate flocculating settling agent in the tank to accelerate the precipitation of the solid content in the sludge. Since dredging sludge generally has a high water content, it is better to reduce the water content of the sludge to about 100 to 150% based on the weight of the solid content and concentrate it in a sludge-like form in the second step. The decrease in water content also reduces the volume of sludge, and the amount of solidifying agent added in the next step can be suppressed to a low level, which is economically advantageous.

Next, in the third step, the sludge-like sludge is solidified with the solidifying material 6
To mix. Various cements and the like are known as solidifying materials, but fly ash 50 to be proposed by the present inventor
A composition consisting of 80%, lime 15 to 40% and aluminum salt 5 to 10% (JP-A-60-54799) can be advantageously applied in achieving the object of the present invention. A particularly suitable solidifying material is at least about 10% by weight, preferably at least about 13.5% by weight.
3CaO.Al ₂ O ₃ component and at least about 20% by weight, preferably at least about 26% by weight CaSO ₄ .2H ₂ O component, and the balance mainly consisting of 3CaO.SiO ₂ and 2CaO.SiO ₂ . It is a calcium silicate composition that does not form a component and can contain a small amount of Fe ₂ O ₃ . Such a composition reacts with water in sludge and solidifies while forming a hydrate, which has so-called hydraulic properties, and the calcium aluminate and calcium sulfate components are at least about 50% by weight of the total solidifying material,
It preferably produces at least about 60% of the ettringite phase, namely 3CaO.Al ₂ O ₃ .3CaSO ₄ .32H ₂ O, and has a remarkably excellent water absorbing ability.

Such a solidifying material exerts a solidifying action even in water,
In order to ensure a more rapid hardening in water, it is also possible to use a rapid solidifying material to which, for example, a small amount of calcium chloride or 11CaO.7Al ₂ O ₃ .CaF ₂ is added.

The amount of the solidifying agent added varies depending on the sludge content, but in the case of concentrated sludge having a water content of 100 to 150% by weight, about 200 to 350 Kg per cubic hedron is suitable.

The solidifying material may be added by a known or common appropriate means such as a mechanical mixer 7 such as a kneader or a mortar mixer, a static mixer provided in a mud-sending pipeline, or a method of taking out the on-site mixed material with a backhoe. it can. It goes without saying that auxiliary use of other hydraulic material in addition to the above-mentioned solidifying material does not matter.

Thus, after the sludge and the solidifying material are mixed, the process proceeds to the fourth step within a relatively short period of time, usually within about 2 hours, preferably within about 1 hour.

As the mold bag 8 in the fourth step, a flexible and high-strength water-permeable sheet material, for example, a bag-shaped article made of synthetic fiber cloth is applied. Such mold bags are known as Shoko 54-32804 and Shoko Sho.
It is known from 46-25345 and Japanese Patent Publication No. 48-10574. The mold bag 8 is previously spread on the construction surface or above the water surface so as to cover the embankment slopes, bottom surface, etc. of rivers, lakes and marshes, and the mixture is held by the pump 9 at the end of the mold bag. Inject and fill the inside from the inlet. When the mold bag is expanded above the water surface, the weight of the sludge-solidifying material mixture settles as it fills, forming a layer of structure that covers the bottom of the water. The fourth step is completed when the mold bag is filled evenly.

The final fifth step is a step in which the solidifying material reacts with water taken from the sludge to form a hydrate and hardens. As described above, in the method of the present invention, the solidifying material produces ettringite having a high hydration rate, and therefore has a significantly large water-absorption ability, and is suitable for densely compacting the fine powdery granular solids contained in the sludge. It exerts a solidification function of adjusting to an appropriate amount of water required for the lubrication action and the approach of particles. The solidified structure molded in this way is a finely-divided solid state in which finely-divided solids derived from sludge are uniformly dispersed and mixed and filled in a calcium silicate-based inorganic hydrate matrix containing an ettringite phase as a main component. And its 28-day intensity is
At least 250 tons / m ² in uniaxial compressive strength according to JIS standard established test method, 350 tons / m ² in a preferred embodiment
It also shows a surprising value.

Although the above description has described sludge, the solidifying material is mixed with finely powdered industrial waste such as fly ash and made into an aqueous sludge form, or both are mixed in powder form and then kneaded with water. The same solidified reinforcing structure can be constructed by using one.

(Operation) The main point of the method of the present invention is that the solidified reinforced structure is characterized by the fact that in the structure of this type, conventional cement concrete for civil engineering and construction such as Portland cement was used, whereas in the present invention, The point is that a small amount of solidifying material is applied by using the solid content or industrial waste derived from sludge that is dredged at the construction site.

Although the mechanism of the excellent solidifying function controlled by the solidifying material is not fully understood in many parts, it can be theoretically explained as follows in comparison with the hydraulic mechanism of ordinary Portland cement.

To solidify the particulate solids in the slurry, as described above,
The amount of water must be adjusted to the range necessary to exert a lubricating effect to compact and compact the particles and bring the particles close together. For this reason, it is said that the solidifying material is required to have a water absorbing function for surplus water.

Normal Portland cement has a composition as shown in Table 1 and exhibits a hydration rate of about 24%.

Typical reaction formulas ordinary portland cement is cured, as represented by _{3CaO · SiO 2 + 3H 2 O} → 1.5CaO · SiO 2 · 1.5H 2 O ( _{tobermorite) +1.5 (CaO · H 2 O} ) Most of the amount of water involved in the hydration reaction is spent in the reaction of calcium silicate to produce tobermorite. While the hydration rate of tobermorite is about 16%, that of ettringite is about 46%, but since calcium sulfate of ordinary Portland cement is within 4%, the amount of ettringite that can be produced from it is 9.7. %
Is the limit.

On the other hand, Table 2 shows a typical chemical composition of the solidifying material applied to the method of the present invention.

The formation of ettringite in the solidified material is represented by the formula: 3CaO ・ Al ₂ O ₃ + 26H ₂ O + 3CaSO ₄・ 6H ₂ O → 3CaO ・ Al ₂ O ₃・ 3CaSO ₄・ 32H ₂ O For example, 3CaO in 100g of solidified material
-Etlingite 79.5 g is theoretically produced from 17.1 g of Al ₂ O _{3 and} 32.7 g of CaSO ₄ / 2H ₂ O.

Since the calcium sulfate dihydrate content in the composition of Table 2 is 26.0%, the amount of ettringite produced in this case is limited by the amount of calcium sulfate and is about 63 g.
Therefore, even in this case, ettringite equivalent to 6.5 times that of Portland cement is produced, and a surprising amount of water is fixed. It is considered that such water-absorption ability appropriately controls the amount of water in the slurry and effectively acts on the densification of the particulate solid matter, and controls the function of forming a tough solidified reinforcing structure.

(Example) Next, this invention is demonstrated about an Example. % In the examples
Indicates weight percent.

Example 1 Graft and weft density using 840 denier nylon filament yarn
24 × 20 plain woven fabrics were woven per 2.54 cm. Two pieces of the above woven cloth having a width of 96.5 cm were cut into a length of 200 cm, and two pieces were laminated, and the peripheral edge was sewn to leave a bag-like shape with 20 cm of the short side being left for the inlet. At the intersection of the imaginary line that divides this into 4 equal parts in the width direction and 5 equal parts in the length direction, insert a nylon gut with a length of about 10 cm in the thickness direction, and put plastic locking pieces on both ends of the gut. A mold bag was created by binding and controlling the separation of the laminated cloth in the thickness direction. This mold bag was set up on the slope of Numagishi and prepared.

On the other hand, sludge containing mud was dredged from the bottom of the swamp, and coarse sand and gravel and dust were sifted by a three-stage automatic sieve and supplied to a bottomed cylindrical thickener with a volume of 1 m ³ . The thickener is equipped with a blade-type stirrer having a vertical rotating shaft in the center, an overflow port at the upper part, and a concentrated sludge discharge port at the lower part. At this time, the amount of sludge supplied was 15 l / min, and the rotation speed of the stirrer was 6 R.PM. The sludge sludge settled on the bottom of the thickener was taken out from the outlet and supplied to the mortar mixer. The slurry has an average particle size of about 80 μm and a solid content of 43% (based on solid content of 132.6
%)Met. In the mortar mixer, a solidifying material having the chemical composition shown in Table 2 (Autoset # 3200, Osaka City, made by Autoset Co., Ltd.) was added for 230 K per 1 cubic rice cake.
It was added at a rate of g and mixed with stirring. The resulting mixture was injected by a pump from an injection port located at the upper edge of the mold for 30 to 45 minutes after mixing, and was press-fitted into the entire mold bag so that it could be spread without corners.

The solidified material in the mixture molded in the mold bag rapidly hydrated and hardened, and after a curing period of one week, an extremely strong structure was formed. When the 28-day strength of the structure was measured, the uniaxial compressive strength was 315 tons / m ² .

Example 2 In the same manner as in Example 1 except that an aqueous slurry of fly ash discharged from a boiler of a power plant (solid content: 48%, solid content reference water content: 108.3%) was used instead of the sludge slurry. A model of a slope protection structure was manufactured. 28-day strength (uniaxial compressive strength) of the obtained structure is 305 tons / m
^{Was 2} .

(Effects of the Invention) The present invention has the above-described configuration, and the coating structure for protecting and stabilizing the surface interface in contact with surface water is represented by sludge or fly ash without using any Portland cement. The value of raw materials such as industrial waste can be used as the main raw material, so it can be constructed at an extremely low cost, and at the same time the cost required for the treatment of dredged sludge or industrial waste can be achieved. Effect is large. Especially when constructing revetments and retaining walls such as dams and reservoirs that are often constructed in steep mountain areas or in remote areas where transportation is inconvenient, sludge dredged from the lake bottom can be used directly as the main raw material. Almost all the difficulties are solved, and an artificial lake or a reinforced natural lake protected by a strong permanent reinforcement structure that can withstand heavy rain, earthquakes, etc. can be constructed inexpensively and easily. Moreover, the lakes and marshes dredged the sludge and covered with a layer of solidified structure on the bottom surface do not have water pollution due to sludge suspension.
This has the effect of significantly increasing the water intake capacity and helping to eliminate water shortages during the dry season. Furthermore, according to the method of the present invention, environmental pollution due to industrial waste such as dredging sludge or fly ash is prevented, and weathering, erosion, collapse, scouring, water pollution of quays, which were conventionally regarded as a kind of natural disaster, etc. Can be prevented, which can greatly contribute to environmental conservation.

[Brief description of drawings]

 FIG. 1 is a schematic explanatory view showing the steps of the method of the present invention. 1 ... Sludge, 2 ... Underwater sand removal robot 3 ... Multistage sieve, 4 ... Sedimentation tank, 5 ... Stirrer, 6 ... Solidifying material, 7 ... Mixer, 8 ... Mold bag, 9 ... Pump

Claims (5)

[Claims] 1. A mold bag made of a water-permeable sheet is mixed and filled with fine powdery granular solids derived from sludge or industrial waste and an inorganic hydrate matrix composed of at least 50% by weight of an ettringite phase, and densely solidified and molded. A solidified reinforced structure having a 28-day strength of at least 250 ton / m ² in uniaxial compressive strength. 2. The solidified reinforced structure according to claim 1, wherein the ettringite phase is at least 60% by weight. 3. The ground surface that comes into contact with surface water is covered and protected.
When constructing a solidification reinforcement structure to be stabilized, the water content of sludge dredged from the bottom of the water or the aqueous sludge of finely divided industrial waste is set to about 100-150% based on the weight of solid content, and the obtained sludge is used as a solidifying material. , At least 10% by weight of 3CaO ・ Al
And ₂ O ₃ component, comprises a CaSO ₄ · 2H ₂ O component of at least 20 wt%, the balance being added to and mixed with the calcium silicate hydraulic compositions based on 3CaO · SiO ₂ and 2CaO · SiO ₂ Then
A method for producing a solidified reinforced structure, characterized by injecting and filling this into a mold bag that has been spread on the construction surface in advance to solidify it. 4. The solidifying material is at least 13.5% by weight of 3CaO.Al.
And ₂ O ₃ component, comprises a CaSO ₄ · 2H ₂ O component of at least 26 wt%, the balance being calcium silicate hydraulic compositions based on 3CaO · SiO ₂ and 2CaO · SiO ₂ patents The method for producing a solidified reinforcing structure according to claim 3. 5. The method for producing a solidified reinforced structure according to claim ^3, wherein the solidifying material is added in an amount of about 200 to 350 kg per 1 m ^{3 of} sludge.