JP2011132106A - Hydraulic composition and cured product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic composition which can suppress an alkaline aggregate reaction even if an aggregate containing silicon dioxide is used. <P>SOLUTION: The hydraulic composition includes an aggregate containing silicon dioxide and a low heat Portland cement. Preferably, the hydraulic composition contains 20-70 pts.wt. of the low heat Portland cement to 100 pts.wt. of the silicon dioxide. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydraulic composition and a cured product obtained by curing the hydraulic composition.

  Conventionally, in hardened bodies such as mortar and concrete, there is a problem that the hardened body may expand due to an alkali-aggregate reaction that occurs between an alkali such as potassium or sodium and the aggregate to cause cracks. . In order to suppress such an alkali-aggregate reaction, it is said that it is preferable to adopt the one described in JIS A5308 as the hydraulic composition that is a precursor of the cured body.

That is, in such a hydraulic composition, it has been proposed to employ at least one of the following three measures.
The countermeasures are, firstly, use of an aggregate determined to be “harmless” by an alkali silica reactivity test in accordance with JIS A1145 or A1146, and secondly, a blast furnace cement suitable for JIS R5211 blast furnace cement [ B type or C type], a fly ash cement suitable for JIS R5213 fly ash cement [type B or C type] or a cement in which an admixture such as blast furnace slag or fly ash is mixed with Portland cement, The total alkali contained in 1 m ³ of concrete is 3.0 kg or less in terms of Na ₂ O.

  Therefore, in the case of using a hydraulic composition containing an aggregate determined to be “non-hazardous” by the alkali silica reactivity test, the second or third countermeasure is adopted, and the alkali bone of the cured body is adopted. In general, the material reaction is suppressed.

  However, for example, in a hydraulic composition using as an aggregate a chart that contains silicon dioxide that promotes alkali-aggregate reaction as a main component and is determined to be “non-hazardous” by the alkali-silica reactivity test. There is a problem that the alkali aggregate reaction of the cured body cannot be sufficiently suppressed even if the above-described second or third countermeasure is adopted. Moreover, when using a hardened | cured body on the beach etc., since it exists in the environment where alkali is supplied from seawater etc., there exists a problem that an alkali aggregate reaction is not fully suppressed also by a 3rd countermeasure.

  On the other hand, in order to suppress the alkali aggregate reaction in the cured body, while adopting an aggregate that contains silicon dioxide and is determined to be “non-hazardous” by the alkali silica reactivity test, an alkali metal substance is used. The hydraulic composition which mix | blended the quick setting agent and blast furnace slag or fly ash which contain is proposed (patent document 1).

  However, this type of hydraulic composition has a problem that the alkali-aggregate reaction of the cured body may potentially be accelerated by the alkali derived from the alkali metal substance incorporated.

JP 2004-331423 A

  Therefore, there is a demand for a hydraulic composition capable of suppressing the alkali aggregate reaction in the cured body even when using an aggregate containing silicon dioxide that can promote the alkali aggregate reaction.

  This invention makes it a subject to provide the hydraulic composition which can suppress the alkali-aggregate reaction in a hardening body even if it uses the aggregate containing silicon dioxide in view of the said problem, a request point, etc. Another object of the present invention is to provide a cured product obtained by curing the hydraulic composition.

  In order to solve the above problems, the hydraulic composition according to the present invention includes an aggregate containing silicon dioxide and low heat Portland cement.

  According to the hydraulic composition having the above-described configuration, the hydraulic composition contains low-heat Portland cement, despite using an aggregate containing silicon dioxide that can cause an alkali-aggregate reaction. Thus, the alkali aggregate reaction of the cured product obtained by curing the composition is suppressed.

  In the hydraulic composition according to the present invention, the aggregate containing silicon dioxide may be an aggregate determined as “non-hazardous” by the test method specified in JIS A1145 or the test method specified in JIS A1146. preferable.

  Moreover, it is preferable that the hydraulic composition which concerns on this invention contains 20-70 weight part of said low heat Portland cements with respect to 100 weight part of aggregate containing the said silicon dioxide.

  The cured body according to the present invention is characterized in that the hydraulic composition is cured.

  In the present specification, the term “low heat Portland cement” means a cement that conforms to the low heat Portland cement defined in JIS R5210.

  As described above, the hydraulic composition according to the present invention has an effect that the alkali aggregate reaction can be suppressed even when the aggregate mainly composed of silicon dioxide is used.

The graph which shows the expansion coefficient with time of a mortar hardening body. The graph which shows the expansion coefficient with time of a concrete hardening body.

  Hereinafter, an embodiment of the hydraulic composition according to the present invention will be described.

  The hydraulic composition of the present embodiment includes an aggregate containing silicon dioxide and low heat Portland cement.

The low heat Portland cement complies with the regulations described in JIS R5210.
Since the hydraulic composition contains low heat Portland cement, the hydraulic composition contains a relatively large amount of belite (C ₂ S). And it is estimated that the property of belite that the progress rate of the hydration reaction is relatively small affects the progress of the alkali-aggregate reaction after curing, and suppresses the progress of the alkali-aggregate reaction. From such a viewpoint, the low heat Portland cement preferably has a belite (C ₂ S) content of 40% or more.

  The amount of the low heat Portland cement in the hydraulic composition is not particularly limited, but is usually 20 to 70 parts by weight with respect to 100 parts by weight of the aggregate containing silicon dioxide, preferably 35 to 55 parts by weight.

  Examples of the aggregate containing silicon dioxide include a pulverized rock containing a mineral containing silicon dioxide, and examples of the mineral containing silicon dioxide include quartz, sparlite (tridymite), and cristobalite. , Cosite, or stishovite. Examples of rocks containing quartz include sedimentary rocks such as charts and sandstones, igneous rocks such as rhyolite and granite, or metamorphic rocks such as quartzite.

  Specifically, as the aggregate containing the silicon dioxide, a crushed material of a chart, a pulverized material of sandstone, or the like may be employed. In addition, these aggregates can be employed singly or in combination of two or more.

  Further, as the aggregate containing the silicon dioxide, the aggregate determined as “non-hazardous” by the test method specified in JIS A1145, and the aggregate determined as “non-hazardous” by the test method specified in JIS A1146 Alternatively, an aggregate determined to be “non-harmful” by both the test method specified in JIS A1145 and the test method specified in JIS A1146 may be employed.

  The aggregate containing silicon dioxide has a dissolved silica amount of 40 mmol / L or more and 450 mmol / L or less according to the test method specified in JIS A1145, and an alkali concentration reduction amount of 45 mmol according to the test method specified in JIS A1145. Those that are not less than / L and not more than 70 mmol / L and are determined to be “non-hazardous” can be suitably employed.

  Further, as the aggregate containing silicon dioxide, those having an expansion rate of 0.150% or more and 0.250% or less as defined in JIS A1146 at a material age of 26 weeks can be suitably used.

  The size of the aggregate containing silicon dioxide is not particularly limited, but includes a coarse aggregate that contains 85% or more by weight in a 5 mm sieve, and passes through all 10 mm sieves and is 5 mm or less. A fine aggregate containing 85% or more by weight can be used as the aggregate.

The amount of the aggregate containing the silicon dioxide in the hydraulic composition is not particularly limited, usually, a 1000~2000kg / m ^3, preferably from 1200~1800kg / m ^3.

  The hydraulic composition may further include cement other than low heat Portland cement, aggregate other than aggregate containing silicon dioxide, water, concrete admixture, blast furnace slag, fly ash, limestone, if necessary. Admixtures such as flour may be included.

  Cements other than the low heat Portland cement that can be blended in the hydraulic composition can be blended within a range that does not impair the effects of the present invention. Examples of the cement include ordinary Portland cement, moderately hot Portland cement, early-strength Portland cement, ultra-early strong Portland cement, sulfate-resistant Portland cement, and the like. Also included are mixed cements such as blast furnace cement, fly ash cement, and silica cement, ultrafast cement such as alumina cement and jet cement, and Irwin cement.

  The water which can be mix | blended with the said hydraulic composition is not specifically limited, A tap water, groundwater, industrial water, etc. are employ | adopted. The water is preferably one having a relatively low content of alkali such as potassium or sodium in that it further suppresses the alkali aggregate reaction in the cured product obtained by curing the hydraulic composition.

  Further, in the hydraulic composition of the present embodiment, conventionally known additives such as a high-performance water reducing agent, an antifoaming agent, a foaming agent, a thickener, a rust preventive agent, etc., as long as the effects of the present invention are not impaired. Can be formulated.

  The hydraulic composition can be produced by performing a kneading process in which an aggregate containing silicon dioxide and a low heat Portland cement are mixed and kneaded.

In the kneading step, a conventionally known general method can be employed.
Specifically, for example, by mixing a part of the raw materials other than water, first knead empty, then add the remaining part of the water and raw materials, mix and perform the main kneading to mix the mixing step. Can be done.

  In the mixing step, a conventionally known general mixing device can be used. That is, for example, kneading can be performed using an apparatus such as a mortar mixer, a concrete mixer, and a kneader.

  Then, the hardening body of this embodiment and its manufacturing method are demonstrated.

The cured body of the present embodiment is obtained by curing the hydraulic composition.
Further, the shape of the cured body is not particularly limited, and examples thereof include a plate shape, a rod shape, and a pipe shape.

  The cured body of the present embodiment can be produced by curing by performing a molding process for molding the kneaded hydraulic composition and a curing process for curing the molded cured intermediate.

In the molding step, usually, the hydraulic composition kneaded in the kneading step is placed in a mold having a predetermined shape and molded to produce a cured intermediate.
As a method for molding the hydraulic composition, other general methods, that is, a papermaking method, a press molding method, an injection molding method, an extrusion molding method, or the like can be employed.

In the curing step, the cured intermediate produced in the molding step is cured. As a method for curing the cured intermediate, a conventionally known general method can be employed.
Specifically, for example, in the curing step, the curing intermediate can be cured for about 2 hours to 5 days under conditions of 30 to 80 ° C. and a relative humidity of 80% or more. Further, for example, steam curing can be performed at 60 to 90 ° C. for about 2 hours to 5 days.

  In addition, the said hardened | cured material can be used in the field | area of a building or civil engineering, such as comparatively large-sized concrete structures, such as a high-rise building, for example.

The present invention is not limited to the hydraulic compositions and cured bodies exemplified above.
Moreover, the various aspects used in a general hydraulic composition and a hardening body are employable in the range which does not impair the effect of this invention.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

  As shown below, a hydraulic composition (a mortar composition, a concrete composition) and a cured product thereof were produced.

  In each of the following examples and comparative examples, a mortar composition and a concrete composition were produced using the raw materials shown below. And the hardening body was manufactured using each composition. First, the raw materials (aggregate and cement) used in each example and each comparative example are shown below.

[Raw material (aggregate)]
Aggregate F (gravel): crushed material chart
Kyoto Prefecture, density 2.62 g / cm ³
Aggregate G (crushed stone): denatured chart / sandstone = 1/9 (weight ratio)
Shiga prefecture, density 2.65g / cm ³

Table 1 shows the results of the tests specified in JIS A1145 and JIS A1146 for each of the aggregate F and aggregate G.
Table 2 shows the results of observing the cross section of each of the aggregate F and the aggregate G with a polarizing microscope.

[Raw material (cement)]
L: Low heat Portland cement (according to JIS R5210)
(Made by Sumitomo Osaka Cement Co., Ltd., density 3.21 g / cm ³ ,
Blaine specific surface area [R 5201] 3,470 cm ² / g)
N-1: Ordinary Portland cement (according to JIS R5210)
(Density 3.15 g / cm ³ manufactured by Sumitomo Osaka Cement Co., Ltd.
Blaine specific surface area [R 5201] 3,410 cm ² / g)
N-2: Ordinary Portland cement (according to JIS R5210)
(Density 3.15 g / cm ³ manufactured by Sumitomo Osaka Cement Co., Ltd.
Blaine specific surface area [R 5201] 3,380 cm ² / g)
N-3: Ordinary Portland cement (according to JIS R5210)
(Density 3.15 g / cm ³ manufactured by Sumitomo Osaka Cement Co., Ltd.
Blaine specific surface area [R 5201] 3,350 cm ² / g)
H: Early strong Portland cement (according to JIS R5210)
(Sumitomo Osaka Cement Co., Ltd. density 3.13 g / cm ³ ,
Blaine specific surface area [R 5201] 4,680 cm ² / g)
BB: Blast furnace cement type B (according to JIS R5211)
(Density 3.05 g / cm ³ , manufactured by Sumitomo Osaka Cement Co., Ltd.,
Blaine specific surface area [R 5201] 3,970 cm ² / g)
FB: Fly ash cement type B (according to JIS R5213)
(Sumitomo Osaka Cement Co., Ltd. density 2.95 g / cm ³ ,
Blaine specific surface area [R 5201] 3,500 cm ² / g)

  Table 3 shows the alkali amount of each cement analyzed according to JIS R5202.

[Raw material (water)]
Water: tap water

Example 1
Using the above-described aggregate F and cement L, a kneading process was performed with the following composition composition to produce a mortar composition. And a hardening process was manufactured by performing a formation process and a curing process with respect to this composition.
Aggregate F: 1350g
Cement L: 600g
Tap water: 300g

[Kneading process]
According to the above composition, the mortar composition was kneaded with a 5 L mortar mixer in a constant temperature room at 20 ° C. The details of the material charging method and kneading method are as follows.
First, all raw materials other than water are charged into the mixer, and the mixer is spun at a low speed (spinning speed 140 ± 5 rpm, revolution speed 62 ± 5 rpm) for 30 seconds. After kneading for 2 seconds, the mortar composition was scraped off, and the number of rotations of the mixer was switched to a high speed (autorotation speed 285 ± 10 rpm, revolution speed 125 ± 10 rpm), and main kneading was performed for 120 seconds.

[Molding process]
The kneaded mortar composition was immediately packed into two layers in a forming steel mold (inner dimensions: width 40 mm × length 160 mm × depth 40 mm). That is, first, the mortar composition was packed up to a height of 1/2 of the mold, and pierced about 15 times for each specimen so that the tip of the piercing bar was 5 mm. Next, the mortar composition was packed so as to rise about 5 mm from the upper end of the mold, and pierced in the same manner using a stick. Finally, the surplus portion was carefully cut away so as not to damage the specimen, and the upper surface of the specimen was smoothed. In this way, three cured intermediates were produced.

[Curing process]
These cured intermediates were placed in a moisture box together with the mold and subjected to initial curing for about 24 hours, then demolded, and then cured for 4 weeks under conditions of 40 ° C. and humidity of 95% or more.
As described above, a cured body was produced from the mortar composition.

(Comparative Examples 1-6)
A concrete composition was produced in the same manner as in Example 1 except that cement N-1, cement N-2, cement N-3, cement H, cement BB, and cement FB were used instead of cement L, respectively. A cured product was produced in the same manner as in Example 1.

(Example 2)
A concrete composition was produced in the same manner as in Example 1 except that aggregate G was used instead of aggregate F. A cured product was produced in the same manner as in Example 1.

(Comparative Examples 7-12)
Example except that aggregate G is used instead of aggregate F, and cement N-1, cement N-2, cement N-3, cement H, cement BB, and cement FB are used instead of cement L, respectively. A concrete composition was produced in the same manner as in Example 1. A cured product was produced in the same manner as in Example 1.

  Table 4 shows a list of types and amounts of raw materials (aggregate, cement, water) used in each example and each comparative example.

<Expansion evaluation of cured body>
The cured bodies of each Example and each Comparative Example were tested according to the so-called Danish method, and their expansion was evaluated. In the Danish method, the cured body cured for 4 weeks was immersed in a saturated NaCl aqueous solution in an environment of 50 ° C., and the test was performed under conditions where alkali was supplied to the cured body. The time points for evaluation were a plurality of time points 1 to 52 weeks after immersion in a saturated NaCl aqueous solution. The results are shown in FIGS.

  From FIG.1 and FIG.2, the expansion | hardening body by which the hydraulic composition of this embodiment hardened | cured has suppressed expansion over a long period of time, even if it is the conditions where an alkali is supplied to a hardening body, It is recognized that the alkali aggregate reaction is excellent in suppressing ability.

Claims (4)

  A hydraulic composition comprising an aggregate containing silicon dioxide and low heat Portland cement.   2. The hydraulic property according to claim 1, wherein the aggregate containing silicon dioxide is an aggregate determined to be “non-hazardous” by a test method specified in JIS A1145 or a test method specified in JIS A1146. Composition.   The hydraulic composition according to claim 1 or 2, comprising 20 to 70 parts by weight of the low heat Portland cement with respect to 100 parts by weight of the aggregate containing silicon dioxide.   Hardened | cured material formed by hardening | curing the hydraulic composition in any one of Claims 1-3.

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