JP2018039699A - Composition for forming solidified body and manufacturing method of solidified body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming a solidified body and a manufacturing method of the solidified body, capable of forming a solidified body excellent in water resistance or acid resistance.SOLUTION: There is provided a composition for forming a solidified body containing water glass and normal Portland cement, the water glass is one selected from a group consisting of sodium silicate, potassium silicate and lithium silicate, and having molar ratio n represented by (Formula 1) in a range of 1.6 to 2.6 and content of a solid component of the water glass of 25 mass% or more. (Formula 1) n=M/M, where Mis molar number of SiOcontained in the water glass, Mis molar number of RO contained in the water glass and R is one or more selected from a group consisting of sodium, potassium and lithium.SELECTED DRAWING: None

Description

  The present disclosure relates to a composition for forming a solidified body and a method for producing the solidified body.

  Aqueous solutions such as sodium silicate, potassium silicate and lithium silicate are collectively referred to as water glass. Compositions containing water glass are used in a wide range of fields and applications as raw materials for inorganic functional materials and civil engineering materials. Patent Document 1 discloses a chemical solution for ground injection containing water glass and fine particle slag as active ingredients. This chemical for injecting ground is injected into the ground and then solidified to form a solidified body.

JP-A-7-166163

  High water resistance and high acid resistance may be required for a solidified body obtained by solidifying a composition containing water glass. The present disclosure provides a composition for forming a solidified body capable of forming a solidified body excellent in water resistance and acid resistance, and a method for producing the solidified body.

  One aspect of the present disclosure is a composition for forming a solidified body comprising water glass and ordinary Portland cement, wherein the water glass is selected from the group consisting of sodium silicate, potassium silicate, and lithium silicate. In the water glass, the molar ratio n represented by the following (formula 1) is within the range of 1.6 to 2.6, and the solid content of the water glass is It is a composition for solidification body formation which is 25 mass% or more with respect to the total amount of the components except the aggregate of the composition for solidification body formation.

(Formula 1) n = M _s / M _R
(M _s is the number of moles of SiO ₂ contained in the water glass, M _R is .R is the number of moles of R _{2 O} contained in the water glass is selected from sodium, potassium, and from the group consisting of lithium 1 or more.)
If the composition for solidified body formation which is one aspect | mode of this indication is used, the solidified body excellent in water resistance or acid resistance can be formed.

  Another form of the present disclosure is a method for producing a solidified body in which the above-described composition for forming a solidified body is solidified to produce a solidified body. According to the method for producing a solidified body which is another aspect of the present disclosure, a solidified body excellent in water resistance and acid resistance can be produced.

An embodiment of the present disclosure will be described.
1. Solidified body forming composition The solidified body forming composition of the present disclosure contains at least water glass and ordinary Portland cement. The solidified body forming composition of the present disclosure may further contain, for example, water, an aggregate, a cement retarder, and the like.

(1-1) Water glass Water glass is a compound generally represented by the following (formula 2). Here, R is an alkali metal, and n is a molar ratio n. N in water glass is generally a real number of 0.5 to 7.5. x is an arbitrary value.

(Formula 2) R ₂ O.nSiO ₂ .xH ₂ O
Examples of the alkali metal in (Formula 2) include sodium, potassium, lithium, and the like.

  The water glass used in the present disclosure is one or more selected from the group consisting of sodium silicate, potassium silicate, and lithium silicate. The water glass may be one of sodium silicate, potassium silicate, and lithium silicate, or may be a mixture of two or more. Examples of the mixture include a mixture of sodium silicate and lithium silicate.

In the water glass used in the present disclosure, the molar ratio n represented by the following (formula 1) is in the range of 1.6 to 2.6.
(Formula 1) n = M _s / M _R
(M _s is the number of moles of SiO ₂ contained in the water glass, M _R is .R is the number of moles of R _{2 O} contained in the water glass is selected from sodium, potassium, and from the group consisting of lithium 1 or more.)
When the molar ratio n is 2.6 or less, it is possible to suppress the occurrence of partial gel or the like due to the immediate reaction between water glass and ordinary Portland cement. As a result, a uniform solidified body can be obtained. Moreover, it can suppress that time until solidification becomes too long because the molar ratio n is 1.6 or more. The molar ratio n is preferably in the range of 2.0 to 2.6. When it is within this range, the load on the environment can be suppressed.

  A water glass having a molar ratio n in the range of 1.6 to 2.6 can be produced, for example, as follows. First, a commercially available water glass having a molar ratio n of 2.0 to 4.7 is prepared. Dissolve silica sources such as fine powdered silica gel, precipitated silica, fumed silica, silica colloid solution, or alkali metal hydroxides such as sodium hydroxide and potassium hydroxide in this commercially available water glass. Thus, the molar ratio n is adjusted within the range of 1.6 to 2.6.

Content of solid content of water glass is 25 mass% or more with respect to the total amount of components except the aggregate of the composition for solidified body formation. By being 25 mass% or more, the compressive strength, warm water resistance, and acid resistance of a solidified body become high. The solid content of water glass means a component remaining after removing a liquid component from water glass. The solid content of the water glass contains SiO ₂ and R ₂ O.

(1-2) Ordinary Portland cement By using ordinary Portland cement, the time until the composition for solidified body solidifies becomes excessively short or excessively longer than when other cements are used. Can be suppressed. As the amount of ordinary Portland cement is increased, the curing start time becomes shorter. The blending amount of ordinary Portland cement is preferably 7 to 40 parts by mass or less with respect to 100 parts by mass of water glass (including liquid components). When it is 7 parts by mass or more, the curing start time can be prevented from becoming excessively long. When it is 40 parts by mass or less, it is possible to suppress a decrease in workability due to excessively short curing start time.

(1-3) Aggregate As the aggregate, an aggregate having alkali resistance characteristics is preferable. Examples of the aggregate include silica sand and ceramics. The aggregate content in the composition for forming a solidified body is not particularly limited, and can be adjusted according to the purpose and application.

(1-4) Water Water has a function of adjusting the viscosity of the solidified composition, for example. Moreover, when the composition for solidified body formation contains the cement retarder mentioned later, water has a function which melt | dissolves a cement retarder. The water content in the composition for forming a solidified body is not particularly limited. For example, the content of water can be adjusted so that the solid content of water glass is 25% by mass or more based on the total amount of components excluding the aggregate of the solidified body-forming composition.

(1-5) Cement retarder The cement retarder has a function of suppressing the setting reaction of ordinary Portland cement. Therefore, the hardening start time of the solidified body forming composition can be adjusted by blending the cement retarder into the solidified body forming composition.

  As the cement retarder, for example, a commercially available organic retarder or an inorganic retarder can be used. Examples of cement retarders include phosphate compounds. Examples of the phosphate compound include sodium dihydrogen phosphate and sodium phosphate.

(1-6) Other components The composition for forming a solidified body of the present disclosure may further appropriately include other components within a range where the effects of the present disclosure are exhibited. Examples of other components include bentonite. Bentonite has a function of increasing the viscosity of the composition for forming a solidified body.

(1-7) Effect exhibited by the composition for forming a solidified body A solidified body can be obtained by solidifying the composition for forming a solidified body of the present disclosure. This solidified body has high compressive strength. The solidified body is excellent in acid resistance and hot water resistance. The solidified body can be used for applications such as solidifying fly ash, sludge, coating material binders, civil engineering materials, and the like. Examples of the civil engineering material include an injection material to the ground. Moreover, the composition for solidified body formation of this indication can set hardening start time to an appropriate range.

2. Production method of solidified body A solidified body can be produced by solidifying the composition for forming a solidified body of the present disclosure. For example, the solidified body forming composition can be solidified in a state where the solidified body forming composition and other components are mixed. Examples of other components include fly ash, sludge, components other than the binder in the coating material, soil, sand, and the like. For example, the composition for solidified body formation can be solidified independently. Solidification of the composition for forming a solidified body may be performed in air or in water. Even when the composition for forming a solidified body is solidified in water, the solidified body is excellent in acid resistance and hot water resistance.

<Example>
(1) Manufacture of composition S1-S30 for solidification body formation The composition for solidification body formation of S1-S30 was manufactured by mixing the raw material shown in Table 1 in the compounding quantity shown to the same table.

  P1 to P17 in Table 1 represent the type of water glass used as a raw material. The contents of the water glasses P1 to P17 are as shown in Table 2.

“SiO ₂ (mass%)” in Table 2 represents the mass% concentration of SiO ₂ when the total amount of water glass is 100 mass%. Moreover, “R ₂ O (mass%)” in Table 2 represents the mass% concentration of R ₂ O when the total amount of water glass is 100 mass%.

Water glass P1-P17 was prepared by mixing the following raw materials suitably.
Sodium silicate: Fuji Chemical Co., Ltd. Potassium silicate: Fuji Chemical Co., Ltd. Lithium silicate: Nissan Chemical Industries, Ltd. Sodium hydroxide: Reagent grade Wako Pure Chemical Industries, Ltd. Potassium hydroxide: Reagent grade 1 Wako Pure Chemical Industrial Co., Ltd. Lithium hydroxide monohydrate: Reagent grade Wako Pure Chemical Industries, Ltd. P15 In P15, the molar ratio of sodium to potassium (Na: K) is 1: 1. In P16, the molar ratio of sodium to lithium (Na: Li) is 12: 1. In P17, the molar ratio of potassium to lithium (K: Li) is 2: 1.

“Cement” in Table 1 means ordinary Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.). The specific surface area of this ordinary Portland cement is 3300 cm ² / g. The “retarder” in Table 1 means a cement retarder. The cement retarder is sodium dihydrogen phosphate dihydrate (reagent grade Wako Pure Chemical Industries, Ltd.). “Aggregate” in Table 1 is dry No. 6 silica sand (Asahi Kogyo Co., Ltd.). “Water” in Table 1 is tap water.

  The “solid content ratio” in Table 1 means the ratio of the solid content of water glass to the total amount of water glass, cement, retarder, and water. The total amount of water glass, cement, retarder, and water corresponds to the total amount of components excluding aggregate.

  The “curing start time” in Table 1 means the time from the time when the raw materials are mixed at 20 ° C. to the time when the fluidity of the composition for forming a solidified body disappears. The curing start time was measured for each of S1 to S30. The measurement results are shown in Table 1. “X” in Table 1 means that a uniform solidified product was not obtained.

  In S1 to S17, a uniform solidified body could be obtained. The curing start time in S1 to S17 was 5 to 190 minutes. On the other hand, in S18, since the molar ratio n was small, the curing start time was remarkably long.

In S24 to S27, S29, and S30, since the molar ratio n was large, after mixing the raw materials, water glass and ordinary Portland cement reacted instantaneously to form a gel. As a result, a uniform solidified body could not be obtained. In S19 to S23, the solid content rate was less than 25% by weight, so the curing start time was significantly shortened.
(2) Formation of test body About the composition for solidified body formation of S3, S11, S20, and S21, the test body was formed with the method shown below. The composition for forming a solidified body was placed in a cylindrical mold having a diameter of 50 mm and a height of 100 mm. Next, it was cured for 7 days in the air at 20 ° C. Next, the contents were removed from the mold, and the specimens were further cured for 21 days in the air at 20 ° C. were used as test specimens. This test body is a solidified body solidified in the air.

  Moreover, about the composition for solidification body formation of S4, the test body was formed with the method shown below. The composition for forming a solidified body was placed in a cylindrical mold having a diameter of 50 mm and a height of 100 mm soaked in water. Next, it was cured in water at 20 ° C. for 7 days. Next, the contents were removed from the mold and cured in water at 20 ° C. for another 21 days to obtain test specimens. This test body is a solidified body solidified in water.

(3) Evaluation of test body About the created test body, the compressive strength test, the hydrochloric acid resistance test, and the warm water resistance test were done. Each test method and evaluation criteria are as follows.

(i) Compressive strength test The uniaxial compressive strength was measured with a uniaxial compression tester using a specimen having a material age of 28 days.
(ii) Hydrochloric acid resistance test The specimen prepared in the above (2) was cut to prepare a specimen having a diameter of 50 mm and a height of 25 mm. This specimen was used below. After measuring the weight of the specimen, the specimen was immersed in 300 ml of 5% hydrochloric acid at 20 ° C. for 7 days. Thereafter, the weight of the test specimen was measured again, and the hydrochloric acid resistance ratio was calculated from the following (Equation 3) using the weight before immersion and the weight after immersion. Moreover, the external appearance observation of the test body was performed before and after immersion, respectively.

(Formula 3) Hydrochloric acid resistance ratio (%) = ((weight after immersion) / (weight before immersion)) × 100
Then, the hydrochloric acid resistance value and the result of appearance observation were applied according to the following criteria to evaluate the hydrochloric acid resistance of the test specimen.

○: The hydrochloric acid resistance ratio (%) is 90 to 101%, and the appearance hardly changes.
Δ: Hydrochloric acid resistance ratio (%) was 80 to 89%, and the appearance was slightly changed.
X: The hydrochloric acid resistance ratio (%) was 79% or less, and the appearance was greatly changed.

(iii) Warm water resistance test The specimen prepared in the above (2) was cut to prepare a specimen having a diameter of 50 mm and a height of 25 mm. This specimen was used below. After measuring the weight of the test body, the test body was immersed in 300 ml of ion-exchanged water. Next, the test specimen immersed in ion-exchanged water was put into a dryer at 80 ° C. and held for 7 days. Next, the test specimen immersed in ion-exchanged water was allowed to cool to room temperature, and the weight of the test specimen was measured again. Using the weight before immersion and the weight after immersion, the hot water resistance ratio was calculated from the following (Equation 4). Moreover, the external appearance observation of the test body was each performed before immersion and after immersion.

(Formula 4) Hot water resistance ratio (%) = ((weight after immersion) / (weight before immersion)) × 100
Then, the value of the hot water resistance ratio and the result of appearance observation were applied according to the following criteria to evaluate the hot water resistance of the test specimen.

○: The hot water resistance ratio (%) is 90 to 101%, and the appearance hardly changes.
Δ: The hot water resistance ratio (%) was 80 to 89%, and the appearance slightly changed.
X: The hot water resistance ratio (%) was 79% or less, and the appearance was greatly changed.

  Table 3 shows the results of the compressive strength test, hydrochloric acid resistance test, and hot water resistance test.

  The uniaxial compressive strength in S3, S4, and S11 was high. The higher the solid content in the composition for forming a solid body, the higher the uniaxial compressive strength. In S20 and S21, since the solid content rate in the composition for solidified body formation was smaller than 25 mass%, the uniaxial compressive strength was low.

  The warm water resistance and hydrochloric acid resistance in S3, S4, and S11 were high. In S20 and S21, since the solid content rate in the composition for forming a solidified body was smaller than 25% by mass, the hot water resistance and hydrochloric acid resistance were inferior to those of S3, S4, and S11.

For comparison, a similar test was conducted on 1: 3 mortar (water / cement ratio 50%). In the hydrochloric acid resistance test of 1: 3 mortar, the hydrochloric acid resistance ratio was 83.0%. The surface of 1: 3 mortar was significantly eroded by immersion in hydrochloric acid.
<Other embodiments>
As mentioned above, although embodiment of this indication was described, this indication is not limited to the above-mentioned embodiment, and can carry out various modifications.

  (1) A function of one component in each of the above embodiments may be shared by a plurality of components, or a function of a plurality of components may be exhibited by one component. Moreover, you may abbreviate | omit a part of structure of each said embodiment. In addition, at least a part of the configuration of each of the above embodiments may be added to or replaced with the configuration of the other above embodiments. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

  (2) In addition to the above-mentioned composition for forming a solid body, the present disclosure can be realized in various forms such as a solidified body, a ground injection agent, and a ground improvement method.

Claims (5)

A composition for forming a solidified body comprising water glass and ordinary Portland cement,
The water glass is one or more selected from the group consisting of sodium silicate, potassium silicate, and lithium silicate;
In the water glass, the molar ratio n represented by the following (formula 1) is in the range of 1.6 to 2.6,
The composition for solidified body formation whose content of the solid content of the said water glass is 25 mass% or more with respect to the total amount of the component except the aggregate of the said composition for solidified body formation.
(Formula 1) n = M _s / M _R
(M _s is the number of moles of SiO ₂ contained in the water glass, M _R is .R is the number of moles of R _{2 O} contained in the water glass is selected from sodium, potassium, and from the group consisting of lithium 1 or more.) The composition for forming a solidified body according to claim 1,
The composition for solidified body formation whose said molar ratio n exists in the range of 2.0-2.6. The composition for forming a solidified body according to claim 1 or 2,
A composition for forming a solidified body further containing a cement retarder.   The manufacturing method of the solidified body which solidifies the composition for solidified body formation of any one of Claims 1-3, and manufactures a solidified body. It is a manufacturing method of the solidification object according to claim 4,
The manufacturing method of the solidified body which solidifies the said composition for solidified body formation in water.