JPWO2018025431A1 - Cement additive and cement composition - Google Patents

Abstract

A cement additive and cement that exhibit excellent stability of the solution and can maintain good fluidity of cement concrete and reduce self-shrinkage, as well as reducing effect of hexavalent chromium that has both immediate effect and sustainability. Providing a composition. Lime sulfur compound having a redox potential (ORP) of pH 10 or more and -450 mV or less and one or more selected from naphthalenes, melamines, aminosulfonic acids, polycarboxylic acids or polyethers The cement additive formed by mixing a liquid water reducing agent, the cement additive having a pH of 8 or more of the liquid water reducing agent, and 5 to 15 mass% of Ca in an amount of 5 to 15% by mass in terms of T-Ca The cement additive containing 15 to 30% by mass in terms of TS and 0.03 to 2.0% by mass in terms of MgO, and a cement composition containing the cement and the cement additive, is there.

Description

  The present invention relates mainly to cement additives and cement compositions used in the civil engineering and construction industry.

  In recent years, securing the quality of cement concrete has become more difficult than ever. This is because the cement industry accepts industrial by-products of various directions as raw materials, and the acceptance rate is increasing. This is because trace components derived from these industrial by-products greatly affect the quality of cement.

  In particular, depending on the difference in the content of the minor component, the fluidity and the strength developability largely differ. In addition, the amount of elution of hexavalent chromium and the like are significantly different. However, the role of the cement industry in accepting industrial by-products in various fields will continue to be sought in the future, and even in the case of using a large amount of industrial by-products, cement quality design methods capable of controlling the influence of trace components It has been demanded.

In Patent Document 1, calcium polysulfide, which is a compound containing Ca and S, is supported on an immobilizing material such as quick lime, and harmful heavy metal elution such as hexavalent chromium is eluted without causing a decrease in strength of the modified soil. The ground improvement material which added the function to suppress remarkably is disclosed. Patent Document 2 mainly contains Ca ₈ S ₅ (S ₂ O ₃ ) (OH) ₁₂ · 20 H ₂ O and calcium hydroxide as a fixing agent used for containing heavy metals contained in contaminated soil etc. Heavy metal fixing agents are disclosed. The above-mentioned Ca ₈ S ₅ (S ₂ O ₃ ) (OH) ₁₂ · 20H ₂ O is considered to be produced by the reaction of calcium polysulfide and calcium hydroxide, and as calcium polysulfide, a commercially available lime-sulfur combination agent is used. The use is described. Patent documents 1 and 2 are all related to a heavy metal fixing agent and a ground improvement material for containing harmful heavy metals.

JP 2001-342461 A JP 2004-33839 A

  The present invention is excellent in the stability of the solution, and has the effect of maintaining the good fluidity of cement concrete and the effect of reducing the auto-shrinkage, and additionally, the cement exerts the reducing effect of hexavalent chromium having both immediate effect and sustainability. The purpose is to provide additives and cement compositions.

The inventors of the present invention have made intensive studies to achieve the above object, and the pH is 10.0 or more, preferably obtained by reacting quick lime, sulfur and water, and preferably the redox potential (ORP). It has been found that a cement additive containing a lime-sulfur mixture having a of −450 mV or less, and a cement composition to which the cement additive is added, achieve the above object.
The present invention is based on the above findings, and the gist of the present invention is as follows.
(1) Lime sulfur compound having a redox potential (ORP) of pH 10 or more and -450 mV or less and one or two selected from naphthalenes, melamines, aminosulfonic acids, polycarboxylic acids or polyethers Cement additive made by mixing liquid water reducing agent more than species. (2) The cement additive according to (1), wherein the pH of the liquid water reducing agent is 8 or more. (3) 5 to 15% by mass of Ca is contained in terms of T-Ca, 15 to 30% by mass of S is contained in terms of T-S, and Mg is contained in an amount of 0.03 to 2 in terms of MgO. The cement additive according to the above (1) or (2), which is contained at 0% by mass. (4) A cement composition containing a cement and the cement additive according to any one of the above (1) to (3). (5) The cement composition according to the above (4), wherein the cement additive is contained in an amount of 0.01 to 10 parts by mass with respect to 100 parts by mass of cement. (6) The cement composition according to the above (4) or (5), which comprises portland cement.

  By using the cement additive according to the present invention, hexavalent chromium is excellent in the stability of the solution, the effect of maintaining good fluidity of the cement concrete and the effect of reducing the autogenous contraction, and additionally having both immediate effect and sustainability. The effect such as exerting the reducing action of

Hereinafter, the present invention will be described in detail.
In the present invention, “parts” and “percent (%)” are based on mass unless otherwise specified.
In addition, cement concrete in the present invention is a generic term for cement paste, cement mortar, and concrete.

The lime-sulfur combination agent contained in the cement additive of the present invention is mainly composed of calcium polysulfide (CaS _x , wherein _X represents the number of sulfur atoms), and contains quick lime, sulfur and water. As a raw material, they are solid-liquid separated yellow-brown liquids obtained by reacting them in an autoclave. Conventionally, lime sulfur combinations are mainly known as pesticides of fruit trees.
As the lime-sulfur mixture, those having various composition ratios and characteristics can be obtained depending on the use ratios of quick lime, sulfur and water, which are raw materials, and reaction conditions in an autoclave. That is, the ratio of the raw material quicklime and sulfur: water is preferably 1.2 to 3 parts of sulfur and 2.5 to 5 parts of water, relative to 1 part of quicklime, particularly preferably 1.5 to 2 parts of sulfur and 3 to 4 parts of water are used. In addition, the reaction is preferably performed under pressure conditions of preferably 3.5 to 10 atm, preferably at 140 to 180 ° C. The reaction is preferably carried out in an autoclave.

  It is important for the lime-sulfur mixture of the present invention to have an alkaline region of pH 8.0 or higher. If the pH is less than 8.0, the effects of the present invention, ie, the stability of the solution, the retention of fluidity, the reduction of hexavalent chromium, and the reduction of autogenous contraction may not be sufficiently obtained. Among them, the pH of the lime-sulfur mixture is preferably 9.0 or more, and particularly preferably 10.0 or more. The pH of the lime-sulfur mixture is preferably high, but from the viewpoint of safety of operation, 13.0 or less is preferable.

  Moreover, the redox potential (ORP: vs. Ag / AgCl) possessed by the lime-sulfur mixture of the present invention is preferably −450 mV or less. If the ORP is not in the range of -450 mV or less, the main effects of the present invention, ie, the effect of maintaining fluidity, the reducing effect of hexavalent chromium, and the reducing effect of autogenous contraction may not be sufficiently obtained. Among them, the ORP is preferably -500 mV or less. The lower limit value of the ORP of the lime-sulfur mixture is not particularly limited as long as the effect of the present invention is not inhibited.

The lime-sulfur combination of the present invention preferably contains 5 to 15% of Ca in terms of T-Ca, preferably 15 to 30% of S in terms of T-S, and preferably, Mg is preferably in terms of MgO. Is contained 0.03 to 2.0%.
The content of Ca here is determined by JIS R 5202 “Method of chemical analysis of cement”, the content of S is determined by a carbon / sulfur analyzer, and the content of MgO is determined by ICP emission spectrometry .

If the Ca content is less than 5%, it becomes difficult to have an alkaline region, and if it exceeds 15%, the pH may exceed 13. Among these, the Ca content is preferably 6% or more, particularly preferably 7% or more, preferably 9% or less, and more preferably 8% or less.
If the S content is less than 15%, the elution amount of hexavalent chromium may increase, and if it exceeds 30%, the elution amount of hexavalent chromium may also increase. Among these, the S content is preferably 17% or more, particularly preferably 20% or more, preferably 28% or less, and more preferably 26% or less.
If the content of Mg is less than 0.03%, the effect of maintaining fluidity, the effect of reducing hexavalent chromium, and the effect of reducing autogenous contraction may not be sufficiently obtained. Among these, the content of Mg is preferably 0.07% or more, and particularly preferably 1.0% or more. The higher the content of Mg, the better. However, it is preferable that the content of Mg be 2.0% or less because it may substitute for Ca in the cement hydrate to promote deterioration.

The liquid water reducing agent used in the present invention is not particularly limited and may be naphthalenes, melamines, aminosulfonic acids, polycarboxylic acids or polyethers, and one or more of them may be used. A liquid water reducing agent can be used in combination. Among these, naphthalenes and melamines are more preferable from the viewpoint of solution stability.
When the lime sulfur mixture is in contact with carbon dioxide in the atmosphere for a long time, the pH decreases and precipitates are formed, the stability of the solution decreases, the fluidity retention effect, and the reduction effect of hexavalent chromium, Furthermore, there are cases where the effect of reducing autocontraction can not be sufficiently obtained.
In the present invention, the stability of the solution can be improved by mixing a liquid water reducing agent with the lime-sulfur mixture. It is preferable that it is 10-80 parts with respect to a total of 100 parts of a lime sulfur compound and a liquid water reducing agent, and, as for the usage-amount of the liquid water reducing agent of this invention, it is more preferable that it is 40-60 parts. If the amount is less than 10 parts, the solution stability may be insufficient, and if it is more than 80 parts, the effect of maintaining fluidity, reducing effect of hexavalent chromium, and reducing effect of autogenous contraction can not be sufficiently obtained. There is.

The pH of the liquid water reducing agent of the present invention is preferably 8 or more. When the pH is less than 8, the stability of the solution, which is the effect of the present invention, is insufficient, and the effect of maintaining the fluidity, the reducing effect of hexavalent chromium, and the reducing effect of autogenous contraction can not be sufficiently obtained. There is a case.
It is also possible to use naphthalenes, melamines, aminosulfonic acids, polycarboxylic acids or polyethers adjusted to pH with an alkali material containing an alkali metal or alkaline earth metal.

  As cements used in the present invention, various Portland cements such as normal, early strong, ultra early strong, low heat, moderate heat, and various mixed cements obtained by mixing blast furnace slag, fly ash or silica with these Portland cements, limestone The filler cement which mixed powder, blast furnace slow-cooling slag fine powder, etc. is mentioned. Furthermore, Portland cement such as environmentally friendly cement (eco cement) manufactured using municipal waste incineration ash or sewage sludge incineration ash as a raw material may be mentioned. In the present invention, one or more of the above can be used.

The use amount of the cement additive of the present invention in the cement composition is not particularly limited, but generally, 0.01 to 10 parts is preferable to 100 parts of cement, and 0.05 to 0.5 parts is More preferable. When the amount of the cement additive used is small, the effects of the present invention, that is, the effect of maintaining the fluidity, the reducing effect of hexavalent chromium, and the reducing effect of autogenous contraction may not be sufficiently obtained.
In the present invention, cement and a cement additive are mixed to form a cement composition.

  The form of the contained lime-sulfur mixture used in the cement additive of the present invention is not particularly limited, and any form may be used as long as the effect of the present invention is not inhibited. It is possible to use the liquid as it is or to use a dried liquid.

  In the cement composition of the present invention, in addition to cement and cement additives, fine aggregate such as sand and coarse aggregate such as gravel, and further, expansive material, quick-hardened material, AE agent, dispersant, antifoaming agent , Thickeners, conventional antirust agents, antifreeze agents, shrinkage reducing agents, coagulants, clay minerals such as bentonite, anion exchangers such as hydrotalcite, ground granulated blast furnace slag, and slowly cooled blast furnace slag. Etc. It is possible to use together one or two or more of the group consisting of admixtures such as slag, limestone fine powder and the like within a range that does not substantially inhibit the object of the present invention.

The cement composition of the present invention may be previously mixed in part or all of the above-mentioned components used therein. As a mixing apparatus for mixing various components, any existing apparatus can be used. For example, a tilt cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, a professional shear mixer, a Nauta mixer, and the like can be used.
When the cement additive of the present invention is used as a grinding aid for cement clinker, the above-described effects of the present invention are more significantly exhibited.

  EXAMPLES The present invention will be more specifically described below with reference to examples and comparative examples, but the present invention is not limited to these.

"Experimental Example 1"
Cement additives A to G were prepared by mixing various lime sulfur combinations A to G and liquid water reducing agents A to J shown below in proportions shown in Table 1.
The cement additive was used in an amount of 0.5 part per 100 parts of cement in a cement composition comprising the cement and the cement additive.
The adjusted cement additive was sprayed and mixed into the cement using a hand spray (for spray application, made of polycarbonate, manual operation, volume 2 liters), and was previously adjusted to the cement.
Experiment No. No. 1-9 is experiment No. 1 with respect to ordinary portland cement clinker. After spraying 1-4 cement additives using hand spray (for spray application, made of polycarbonate, manual operation, volume 2 liters), grinding and mixing together with gypsum (4% added internally to cement clinker) To prepare cement (Blaine specific surface area 3300 cm ² / g).

Next, prepare a concrete with a unit cement composition amount of 500 kg / m ³ , a water / cement composition ratio of 33%, a fine aggregate volume ratio to the total aggregate volume of 46%, an air content of 4.5%, and a slump of 21 cm. did. At this time, 1.4 parts of a high performance water reducing agent was added to 100 parts of the cement composition. About this concrete, the time-dependent change of the slump, the auto shrinkage, and the reduction effect of hexavalent chromium were confirmed.
In addition, cement additives A to G prepared by mixing lime sulfur combinations A to G and liquid water reducing agents A to J in proportions shown in Table 1 are put in a 100 ml beaker and stored for 1 week with the top opened. Then, the presence or absence of generation of precipitates, and the volume ratio of precipitates were visually confirmed.
The results are shown in Table 1.

<Material used>
Cement: Ordinary portland cement, brane specific surface area 3210 cm ² / g, using a commercially available product (Denka company, ordinary portland cement).
Ordinary Portland Cement _{Clinker: 3CaO · SiO 2 58.1%,} 2CaO · SiO 2 18.7%, 4CaO · Al 2 O 3 · Fe 2 O 3 10.0%, 3CaO · Al 2 O 3 10.2%. (Firing at 1350 ° C in a kiln)
Plaster: 2 hydrogypsum, commercial products

Lime sulfur compound A: lime sulfur compound, pH 11.0, ORP-540 mV, MgO content 1.0%, T-Ca content 13%, T-S content 26%.
Lime sulfur compound B: Lime sulfur compound, pH 10.5, ORP-500 mV, MgO content 1.0%, T-Ca content 12%, T-S content 24%.
Lime sulfur compound C: lime sulfur compound, pH 10.0, ORP-450 mV, MgO content 1.0%, T-Ca content 11%, T-S content 22%.
Lime sulfur compound D: Lime sulfur compound, pH 10.5, ORP-500 mV, MgO content 0.05%. T-Ca amount 10%, T-S amount 21%.
Lime sulfur compound E: lime sulfur compound, pH 10.5, ORP-500 mV, MgO content 2.0%, T-Ca content 8%, T-S content 19%.
Lime sulfur compound F: lime sulfur compound, pH 11.0, ORP-540 mV, MgO content 1.0%, T-Ca content 13%, T-S content 26%.
Lime sulfur compound G: lime sulfur compound, pH 8.0, ORP-450 mV, MgO content 1.5%, T-Ca content 13%, T-S content 26%.
Lime-sulfur mixture H: 25 parts of the lime-sulfur mixture mixed with 100 parts of quick lime (Blaine specific surface area: 3460 cm ² / g) in a ball mill and supported.
Liquid water reducing agent A: Naphthalenes, naphthalene sulfonate water reducing agent, manufactured by Denka, trade name "FT-500 V", pH = 9
Liquid water reducer B: Naphthalenes, naphthalene sulfonate water reducer, manufactured by Kao Corporation, trade name "Mighty 150", pH = 9
Liquid water reducing agent C: polycarboxylic acids, polycarboxylic acid dispersants, manufactured by Toagosei Co., Ltd., trade name "Aron A210", pH = 8
Liquid water reducer D: Polycarboxylic acids, polycarboxylic acid water reducer, manufactured by Kao, trade name "Mighty 1000 S", pH = 6
Liquid water reducer E: Melamines, melamine powder reducer, manufactured by BASF, trade name "MELMENT F10" dissolved in 25 parts of water, pH = 10
Liquid water reducing agent F: aminosulfonic acids, aminosulfonic acid compounds, manufactured by Floric, trade name "Floric SF 200 S", pH = 7
Liquid water reducer G: aminosulfonic acid, amino sulfonic acid compound, manufactured by Floric, trade name "Floric SF 200 S" adjusted to pH 9 by adding sodium hydroxide reagent Liquid water reducer H: polyether, carboxyl Polyether-based water reducing agent containing soot, manufactured by Kao, trade name "Mighty 3000 S", pH = 6
Liquid water reducer I: Polyethers, carboxyl group-containing polyether based water reducer, manufactured by Kao Corporation, trade name “Mighty 3000S” adjusted to pH 9 by adding sodium hydroxide reagent Liquid water reducer J: Liquid water reducer A mixture of A and C in equal amounts The above-mentioned lime-sulfur combination agents A to G variously change the proportions of quick lime, sulfur and water, respectively, in an autoclave at a pressure of 5 atm and 150 ° C. It contains various lime-sulfur mixtures obtained by reacting and solid-liquid separation.
Moreover, the said lime sulfur compound H is disclosed by patent document 1 (Unexamined-Japanese-Patent No. 2001-342461), The lime sulfur compound used there used what was not carrying out solid-liquid separation.

Fine aggregate: River sand from Himekawa, Niigata, particle size: sieve 5 mm, coarse ratio 2.82, specific gravity 2.64.
Coarse aggregate: Crushed stone from Himekawa, Niigata, maximum particle size 25 mm, coarse particle ratio 6.98, specific gravity 2.62.
High-performance water reducing agent: Polycarboxylate-based, commercially available product (manufactured by BASF, MELFLUX 2651 F).

<Test method>
Solution stability: A mixture of a lime sulfur compound and a liquid water reducing agent is placed in a 100 ml beaker and stored for 1 week with the top open, and the presence or absence of precipitates and the volume ratio of precipitates visually confirmed.
Slump loss: The slump was measured according to JIS A 1150, and the amount of change in the measured value after 30 minutes and after 90 minutes immediately after kneading was examined.
Auto-contraction: Measured according to the report of the JCI Auto-contraction Research Committee. It was displayed as an autogenous strain at 56 days of material age.

The amount of elution of hexavalent chromium: hexavalent chromium standard solution was diluted to hexavalent chromium concentration to prepare a solution of 100 mg / l, concrete the hexavalent chromium solution to a 2 liters relative to the concrete 1 m ³ The water was added in place of water. The amount of elution from fresh concrete not yet solidified and the amount of elution from hardened concrete were examined.
The amount eluted from fresh concrete (immediate effect) was determined by adding hydrochloric acid to pure water and adding a hydrochloric acid to a sample obtained by filtering the supernatant obtained from bleeding or centrifugation 30 minutes after kneading. It mixed with the solution made to become 8 or more and 6.3 or less by the ratio of 10% of a weight volume ratio, and measured by the ICP emission spectrometry according to JISK 0102.
The elution amount (sustainability) from hardened concrete was measured according to Environment Agency Notification No. 46 by crushing hardened concrete after 28 days of material use and using a sample under 2 mm. However, the residual concentration of hexavalent chromium was measured by ICP emission spectrometry according to JIS K 0102.

  From Table 1, by using the cement additive of the present invention, stability of the solution can be obtained, and further, the fluid retention effect, the auto-shrinkage effect are reduced, and the reduction effect of hexavalent chromium is also immediate effect and sustained. I understand that there is a sex.

"Experimental example 2"
The cement additive of Experiment No. 1-4 was used, and the experiment was carried out in the same manner as in Experiment Example 1 except that the amount of the cement additive used was changed as shown in Table 2. The results are shown in Table 2.

  From Table 2, by using a proper amount of the cement additive of the present invention, the fluid retention effect can be obtained, the reduction effect of hexavalent chromium can achieve both the immediate effect and the sustainability, and the autogenous shrinkage can be reduced. It is understood that it is done.

  By using the cement additive and cement composition according to the present invention, a good fluidity retention effect and an auto-shrinkage reduction effect can be obtained, and in addition, the reduction effect of hexavalent chromium having both immediate effect and sustainability is exhibited. It is suitable for a wide range of applications mainly in the civil engineering / building industry etc.

Claims (6)

Lime sulfur compound having a redox potential (ORP) of pH 10 or more and -450 mV or less and one or more selected from naphthalenes, melamines, aminosulfonic acids, polycarboxylic acids or polyethers Cement additive mixed with liquid water reducing agent. The cement additive according to claim 1, wherein the pH of the liquid water reducing agent is 8 or more. The lime-sulfur combination agent contains 5 to 15% by mass of Ca in terms of T-Ca, 15 to 30% by mass of S in terms of TS, and 0.03 to 2.0% by mass of Mg in terms of MgO The cement additive according to claim 1 or 2, which is contained. A cement composition comprising a cement and the cement additive according to any one of claims 1 to 3. The cement composition according to claim 4, wherein the cement additive is contained in an amount of 0.01 to 10 parts by mass with respect to 100 parts by mass of cement. The cement composition according to claim 4 or 5, comprising portland cement.