JPH0553744B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a filler that is injected into the ground or into cavities or voids in buildings to fill them in civil engineering and construction work.

[Conventional technology]

For example, when a road caves in due to a leak in an underground water supply or sewer system, the material to fill it is fluid and can be injected through a pipe. I want something that solidifies without turning into a slurry and shows some strength, but that is easy to dig up later with a shovel or pickaxe. The simplest material is sand, but it has poor fluidity and is difficult to use. If you use Portland cement mortar or concrete, the strength will be too high and it will take time to re-excavate. To keep the strength low, fine aggregate or clay can be mixed in, but this requires a large water-cement ratio, which results in shrinkage during solidification. Compensating for gaps caused by shrinkage by reinjecting mortar would be a waste of time and labor, and would also increase construction costs. Various cement expanding agents have been developed to prevent the shrinkage of Portland cement, but if the water-to-cement ratio is unavoidable, the effect of the expanding agent is canceled out by the large water-to-cement ratio. Unless you use a very large amount of cement expanding agent, you won't be able to make it in time. Needless to say, this is uneconomical. For this reason, the current method of filling cavities and voids is the simultaneous injection of water glass solution and cement milk, and the other is the use of alternatives to cement milk, such as slaked lime milk or lignin sulfone. Injection of acid or its salt, water-soluble acrylic acid resin, emulsion of acrylic acid resin, polyurethane, etc. In tunnel construction, the process of filling in the space between the segment and the excavated ground involves press-fitting foam mortar, which is made by introducing air bubbles into Portland cement. These techniques are ineffective, expensive, or require specialized equipment, and therefore need improvement. Quicklime is a well-known and widely used substance that expands upon hydration. Ordinary (lightly calcined) quicklime obtained by calcining limestone has a too rapid hydration reaction. Hard-burned quicklime, which is fired at high temperatures using coke or coal, has a slower hydration reaction, but hydration progresses rapidly after a certain period of time, and if there is a large amount, the temperature will rise and it will become explosive. A phenomenon occurs. An effective way to retard the hydration of quicklime is to use silicic acid or its salts (typically sodium silicate Na ₂ SiF ₆ ). but,
The use of silicic acid in civil engineering and construction work can only be industrialized in a limited number of situations, as fluorine may cause pollution. The inventors searched for a fluorine-free quicklime hydration retarder and found that sodium silicate was effective. Here, "sodium silicate" is
It includes not only orthosilicate 2Na ₂ O.SiO ₂ .mH ₂ O but also sesquisilicate 3Na ₂ O.2SiO ₂ .mH ₂ O and metasilicate Na ₂ O.SiO ₂ .mH ₂ O.

[Problem to be solved by the invention]

An object of the present invention is to utilize the above-described knowledge of the inventors to provide a composition suitable as a filling material for cavities and voids, thereby contributing to civil engineering and construction technology. In other words, it has fluidity that allows it to be easily injected into cavities and voids, and when an appropriate amount of time has passed after injection, a hydration reaction occurs and solidifies, and at that time, it expands slightly, leaving no voids behind. The strength is such that it can be re-excavated (compressive strength of 2 to 60 kg/cm ² ),
Moreover, it is an object of the present invention to provide a filling material that is inexpensive to manufacture and install.

[Means to solve the problem]

The cavity or cavity filler composition of the present invention essentially comprises hard-calcined quicklime, aggregate, and at least one quicklime hydration retardant selected from sodium orthosilicate, sodium sesquicate, and sodium metasilicate. It consists of a drug. In addition to sodium silicate, which is a hydration retarder,
It is preferable to add one or more selected from sugar, oxycarboxylic acid or its salt, aminocarboxylic acid or its salt, water-soluble protein, and dihydrate gypsum. Examples of oxycarboxylic acids are gluconic acid, ketogluconic acid, citric acid, etc.
Use a substance that forms calcium chelate under strong alkaline conditions. Alkali salts, alkaline earth salts, etc. can be used for both oxycarboxylic acids and aminocarboxylic acids. Rothsiel's salt is also useful. A typical composition is that the weight ratio of hard calcined lime is 1 to 1.
10%, hydration retarders and their auxiliaries in total amount
0.1-3%, the rest being aggregate.

[Effect]

This filler composition has high fluidity when kneaded with the addition of an appropriate amount of water, and can be injected into voids using its own weight through an appropriate pipe. The hydration reaction of hard calcined quicklime is delayed by the sodium silicate and does not proceed explosively, and the entire composition hardens at an appropriate rate, resulting in moderate strength. When expansion is restricted in a limited space, the strength is at an upper limit compared to when expansion is not restricted. The strength achieved depends on the composition, of course, but the compressive strength is between 2 and 15 Kgf/cm ² when there is no restraint on expansion, and 20 Kg when there is restraint.
f/cm ² or more. In addition to the basic composition described above, the filler composition of the present invention can be modified by adding various additive components, and by selecting a composition according to the application, it can be used appropriately and at any time. I can do it. For example, when the above basic composition and clay containing allofene is added up to 80% by weight, when mixed with water, it gradually generates heat of hydration after several hours, and the temperature of the composition does not exceed 60°C, while expanding. Hydrate. If the temperature of the mortar does not exceed 60°C under normal conditions, there is no need to worry about the mortar blowing out due to excessive temperature rise under many construction conditions. The self-hardening strength of this solidified mortar is
It is low when it is not under restraint conditions, but when buried in underground cavities or tunnels, it becomes a restraint condition and the expansion is suppressed, resulting in a relatively high strength. Clay containing allofene is often present as the topsoil of ore during limestone mining. It is also effective to add some, typically 1 to 20%, of Portland cement; in this case, it is desirable to use a superplasticizer in combination to prevent an increase in the water-cement ratio. When mixed with water, hydration heat is gradually generated over several hours, and the temperature generally does not exceed 60°C, which is the same as above, but the self-hardening property is higher due to the increased proportion of hydraulic substances. However, the expansion rate is somewhat lower than the above. Addition of small amounts of alumina cement, typically 1-3%, causes hydration to begin relatively quickly when mixed with water, causing the mortar to lose fluidity and solidify prematurely. In this case too, the temperature reached from hydration is 60
The type and amount of hydration retarders and auxiliary agents should be considered so as not to exceed ℃. Preference is given to using oxycarboxylic acids or salts thereof as auxiliaries. This composition is particularly useful when the void is narrow and deep and the purpose of filling can be achieved by pouring mortar to a limited depth and allowing it to solidify. In either case, an appropriate amount of lime sludge produced when limestone is mined and washed, typically 10 to 30% of the composition, may be used as the aggregate.
Lime sludge, which currently has little use and is more of a waste product, can be effectively utilized in accordance with the present invention. The moderate expansion of this filler eliminates the need for conventional foam mortar press-in when used for filling tunnel construction. In applications such as roads, when the filling material of the present invention is used to prevent ground depression,
If the compressive strength of cm ² is exhibited, sufficient soil bearing capacity will be generated. In addition to civil engineering work, the filling material of the present invention is also useful in building work, such as when filling a gap between the wall of a building and the foundation. Example A A filler composition was prepared by blending the following components. (Units are weight%) Hard-calcined quicklime 1.60% Lime sludge 24.06 Sodium orthosilicate 0.05 Sodium carbonate 0.02 Sugar 0.03 Gypsum dihydrate 0.32 Portland cement 6.42 Superplasticizer "Mighty 100" (manufactured by Kao Corporation) 0.13 River sand 67.37 This 22 parts by weight of water was added to 100 parts by weight of the composition and kneaded, and the properties of the mortar, its coagulation behavior, and the properties of the solidified product were examined. The results are as follows. (Mortar) Specific gravity (Breathing amount 1.86%) (Measured in accordance with the Japan Society of Earth Science and Technology method, and the average value of 4 times was taken.) 2.09 Flow value 0 minutes (when adjusting mortar): 50 seconds 30 minutes: 68 seconds (Solidification behavior) Solidification (when fluidity is lost) 120 minutes solidification (when a stainless steel rod no longer sinks in when placed upright) 4 hours and 30 minutes Surface water disappears 30 hours (solidified solid) Unconfined compressive strength 7 days 8.53Kgf/cm ² Breaking strain 1.65% Final expansion 0.93% Example B A filler composition was prepared by blending the following components. Hard burnt lime 4.66% Lime sludge 14.63 Sodium orthosilicate 0.33 Sugar 0.16 Gypsum dihydrate 0.66 Portland cement 11.00 Alumina cement 2.00 Superplasticizer "Mighty 100" 0.06 River sand 66.67 24 parts by weight of water per 100 parts by weight of this composition In addition, the same tests as in Example A were conducted. (Mortar) Specific gravity (breathing amount 0.15%) 2.08 Flow value 0 minutes: 39 seconds 20 minutes: 83 seconds (solidification behavior) Setting 15 minutes Solidification 20 minutes Surface water loss 20 minutes (Solidified solid) Unconfined compressive strength 7 days 3.33Kgf/cm ² Breaking strain 1.40% Final expansion 16.8% Example C A filler composition was prepared by blending the following components. Hard calcined quicklime 6.00% Lime sludge 15.33 Sodium orthosilicate 0.33 Gypsum dihydrate 0.66 Portland cement 9.33 Alumina cement 1.66 Superplasticizer "Mighty 100" 0.06 River sand 66.67 Tested by adding 27 parts by weight of water to 100 parts by weight of this composition did. (Mortar) Specific gravity (maximum breathing amount 0.26%) 2.02 Flow value 0 minutes: 39 seconds 20 minutes: 83 seconds 10 minutes: 72 seconds (solidification behavior) Setting 20 minutes Solidification 1 hour Surface water disappearance 18 minutes (Solidified material ) Unconfined compressive strength 7 days 7.0Kgf/cm ² Breaking strain 2.01% Final expansion 18.0% Example D A filler composition consisting of the following components was prepared. Hard calcined quicklime 2.33% Lime sludge 23.33 Sodium orthosilicate 0.10 Gypsum dihydrate 0.43 Portland cement 7.00 Superplasticizer "Mighty 100" 0.13 River sand 66.67 23 parts by weight of water was added to 100 parts by weight of this composition. The results of tests similar to Examples A to C are as follows. (Mortar) Specific gravity (maximum breathing amount 1.97%) 2.10 Flow value 0 minutes: 26 seconds 20 minutes: 28 seconds 10 minutes: 26 seconds 30 minutes: 36 seconds (solidification behavior) Setting 60 minutes solidification 4.5 hours surface water disappearance 18 hours (solidified) Unconfined compressive strength 7 days 6.80Kgf/cm ² Fracture strain 1.56% Final expansion 2.75% Next, as a test under conditions close to actual construction, we conducted a test in a limestone mine shaft where temperature changes are small throughout the year. The following experiment was carried out using the following. In other words, a PVC resin pipe (diameter 30cm, length 2m) as shown in Figure 1 is made to resemble the underground cavity into which mortar is injected.
Prepare 1, close both ends, attach an injection pipe 2 with a diameter of 5 cm (height 45 cm) above, install 3 temperature sensors 3 in the middle, and pour soil 4 (moisture content about 7%). It was covered to a depth of about 80cm. The mortar described above was injected from one side of the injection pipe 2, and the temperature change over time was examined, and the results shown in FIG. 3 were obtained. This graph shows a sudden rise in temperature (primary peak) about an hour after mortar preparation, i.e. the start of hydration, followed by a slight stagnation.
It shows a tendency to reach the maximum temperature (secondary peak) after 10 hours. Separately, a steel pipe 6 with an inner diameter of 38 mm and a length of 30 cm was prepared, a temperature sensor 8 was installed, strain gauges 7 were attached to two locations on the outside, and the mortar 9 was poured into the shaft. Earth and sand was poured to a thickness of 80 cm. The tendency of expansion/contraction accompanying solidification of mortar was investigated, and the results shown in Figure 4 were obtained. From solidified inside PVC pipe, diameter 10
A cylinder with a height of 12.7 cm and a height of 12.7 cm was cut out, and a uniaxial compressive strength test was conducted after 7 days. The results are as follows. Specimen compressive strength fracture strain D-1 21.6 Kgf/cm ² 1.00% D-2 23.4 1.25 D-3 24.0 1.15 D-4 20.2 1.50 The relationship between compressive stress and axial strain is plotted as shown in Figure 5. Example E A filler composition consisting of the following components was prepared. Hard calcined quicklime 3.63% Lime sludge 21.67 Sodium orthosilicate 0.17 Sugar 0.33 Gypsum dihydrate 0.70 Portland cement 7.00 Superplasticizer "Mighty 100" 0.13 River sand 66.67 23 parts by weight of water were added to 100 parts by weight of this composition, and Example Similar data was obtained by injecting into PVC resin pipes and steel pipes in D. The change in temperature over time is shown in FIG. 6, the trend in expansion pressure is shown in FIG. 7, and the relationship between compressive stress and axial strain is shown in FIG. 8. The compressive strength after 7 days obtained in the same manner as in Example D is as follows.

[Table] Example F A filler composition consisting of the following components was prepared. Hard calcined lime 4.70% Lime sludge 20.33 Sodium orthosilicate 0.23 Sugar 0.33 Gypsum dihydrate 0.90 Portland cement 7.00 Superplasticizer "Mighty 100" 0.13 River sand 66.67 To 100 parts by weight of this composition, 23 parts by weight of water were added, Similar data were obtained by injecting into PVC resin pipes and steel pipes in Example D. The change in temperature over time is shown in FIG. 9, and the relationship between compressive stress and axial strain is shown in FIG. 10. The compressive strength after 7 days obtained in the same manner as in Example D is as follows.

【table】

【Effect of the invention】

The filler of the present invention has sufficient fluidity to be easily injected through pipes into cavities and voids during civil engineering and construction work, and after injection, it hydrates and solidifies without dissolving or disintegrating in water. However, since some expansion occurs at this time, filling can be performed without leaving any voids. The strength can be adjusted to a desired level, as long as it is sufficient to temporarily fill and support cavities and voids, and is easy to re-excavate for full-scale construction later. Because the waste materials associated with the lime industry, such as lime sludge and allofene-containing clay, can be used as filler components, the cost can be extremely low, and it also helps prevent pollution, killing two birds with one stone.

[Brief explanation of the drawing]

FIG. 1 shows one of the apparatuses for testing fillers in an embodiment of the present invention, in which A is a side view and B is a cross-sectional view. FIG. 2 is a longitudinal sectional view of another apparatus for testing fillers according to an embodiment of the present invention. Figures 3 to 10 all show data of examples of the present invention, and Figures 3, 6, and 9 plot changes in temperature due to hydration of filler mortar. Figures 4 and 7 are graphs plotting the state of expansion due to hydration, and Figures 5, 8, and 1
Figure 0 is a graph plotting the relationship between compressive stress and axial strain. 1...PVC resin pipe, 2...Injection pipe,
3, 8...Temperature sensor, 4...Sand, 6...Steel pipe, 7...Strain gauge.

[Claims]

1 (A) 100 parts by weight of gypsum hemihydrate, and (B) 0.1 to less than 5 parts by weight of fibrous gypsum having a length of 10 to 300 μm, a diameter of 0.1 to 10 μm, and an aspect ratio of 20 or more. plaster composition.