JP2007063103A - Quick hardening type high toughness fiber-reinforced ceramic material and method of formulating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish a technique for a repairing and reinforcement process by placing or spraying which is capable of attaining a prescribed effect with minimum curing to early develop the performance of high toughness fiber-reinforced ceramic (FRC) and is effective for reinforced stiffness, the suppression of the occurrence of crack and the improvement of the durability of an existing structure by virtue of the micronization of crack. <P>SOLUTION: In the crack dispersion type high toughness FRC material obtained by blending PVA short fibers to a cement-based formulation material and showing ≥0.2% tensile strain in the tensile test, the tensile strain in a material age of 1-5 days satisfies a required value of ≥0.2% by adding a hardening accelerator consisting essentially of anhydrous gypsum in a ratio by weight of 1/1000-1/3 to cement to be used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rapid-hardening type high-toughness FRC material used as a repair / reinforcing material and a structural material in the field of civil engineering and architecture, and a blending method thereof.

The applicant first blended short fibers, kneaded concrete, mortar, etc., and made three-dimensional random orientation to improve tensile strength and bending strength. PVA fiber reinforced cement composite material generally called HPFRC or ECC Was filed as shown in the following patent document.
Japanese Patent Laid-Open No. 200-7395

  This patent document 1 is in a tensile test. The present invention relates to a crack-dispersed high toughness FRC material exhibiting a tensile strain of 0.2% or more and a method for producing the same.

  In the FRC material, by properly combining the strength, dimensions and blending amount of the PVA fiber to be blended with the material composition of the cementitious matrix, fine cracks cross-linked by the fiber are sequentially formed even if the hardened body is cracked. Due to the mechanism of generation, even if an apparently large strain occurs, it can withstand the load.

  Such a crack-dispersed PVA fiber reinforced cement composite is referred to as a “high toughness FRC material”. This high toughness FRC material is expected to be widely used for reinforcement of road slabs, structural members, repair materials, and the like, taking advantage of its large deformation performance and the feature that cracks are finely dispersed.

  It is known that sufficient curing time and curing period are necessary to demonstrate the tensile performance of high toughness FRC material, especially when the curing performance is insufficient or the curing is insufficient. It has been known.

  In fact, when construction was performed on a new bridge, a two-week curing period was required.

  In high-toughness FRC of spray construction, treatment such as application of a curing agent is indispensable, and sufficient consideration is necessary so that external force and impact are not applied until the high-toughness FRC material exhibits its performance.

  In addition, high toughness FRC materials use various admixtures to obtain fiber reinforcing effects and to suppress drying shrinkage. Due to the influence of these various admixtures, a tendency to delay the initial setting time and the final setting time was observed as compared with general mortar. This means that sufficient curing time is required to cure.

  On the other hand, the repair / reinforcement method using high-toughness FRC material is a repair / reinforcement method that takes advantage of the deformability of high-toughness FRC material and the ability to disperse cracks. The effect of improving the durability due to the suppression of sexualization is considered.

  As repair / reinforcement methods using high-toughness FRC materials, there are a driving method mainly used for floor slabs and a spraying method used for wall surfaces depending on the construction site.

  However, in order to apply high-toughness FRC material to repair and reinforcement of structures currently in use, depending on the construction site, it is necessary to interrupt the use of the structure during the curing period, so take sufficient curing time. However, even if the use of high-toughness FRC is effective, the scope of application as a repair / reinforcement material is limited due to this situation.

  In order to shorten the curing period, simply adding many rapid hardening materials to the conventional high-toughness FRC material will cause the material to harden immediately, making it impossible to construct.

  In addition, the high toughness FRC is not only required to cure rapidly, but also the deformation performance with respect to the tension is important, so that it is necessary to develop the tensile performance.

  The object of the present invention is to solve the above-mentioned inconveniences, in which a short dispersion fiber of PVA is blended in a cementitious compound material, and in a crack-dispersed high toughness FRC material that exhibits a tensile strain of 0.2% or more in a tensile test, An object of the present invention is to provide a rapid hardening type high toughness FRC material that can be shortened, that is, cured in a short time of 1 to 5 days, and at the same time, can exhibit a required tensile performance, and a blending method thereof.

  In order to achieve the above-described object, the present invention provides a rapid-hardening high-toughness FRC material in which a short dispersion fiber of PVA is blended in a cement-based compounding material and a crack dispersion type that exhibits a tensile strain of 0.2% or more in a tensile test. In high toughness FRC material, add 1/1000 to 1/3 by weight ratio of quick hardwood mainly composed of calcium aluminate and anhydrous gypsum to cement used, and age 1-5 Thus, the gist is that the tensile strain satisfies the required value of 0.2% or more in the tensile test.

  In addition, as a method of blending the rapid hardening type high toughness FRC material, first, a short fiber of PVA is blended in a cement-based blended material, and a crack-dispersed type high strength which exhibits a tensile strain of 0.2% or more in a tensile test. In the toughness FRC material, when adding 1/1000 to 1/3 by weight ratio of a rapid hardening material mainly composed of calcium aluminate and anhydrous gypsum with respect to the cement to be used, first, a binder is added to the mixer. , Add a setting retarder and blended water together with aggregate and rapid hardener, or knead, or first add binder, aggregate and blended water to mixer and knead. Addition of rapid hardening material before fiber is added. Secondly, cracked dispersion type high toughness FRC, in which short fiber of PVA is blended in cementitious compounding material and tensile strain of 0.2% or more is shown in tensile test. Material In addition, to the cement to be used, 1/1000 to 1/3 by weight ratio of a rapid hardening material mainly composed of calcium aluminate and anhydrous gypsum is added and a setting retarder is added together with the rapid hardening material. It is a summary.

  In the present invention, simply adding a hard material to a conventional high-toughness FRC material causes the material to harden immediately and cannot be applied. It has been devised by comprehensively examining the types of materials, the ratio of hardened materials, the selection of setting retarders and the production method.

  Moreover, since the deformation performance with respect to the tension is important for the high toughness FRC, it is not only necessary for the curing to proceed rapidly, but also it is necessary to develop the tensile performance. It is something that has been devised to examine the construction method.

  According to the first aspect of the present invention, a cement to be used in a crack-dispersion type high toughness FRC material in which a short fiber of PVA is blended in a cementitious compound material and exhibits a tensile strain of 0.2% or more in a tensile test. On the other hand, by adding 1/1000 to 1/3 by weight ratio of a hardened material mainly composed of calcium aluminate and anhydrous gypsum, the material age is 1 to 5 days depending on the construction conditions. A material having a tensile strain of 0.2% or more can be obtained.

  According to the second and third aspects of the present invention, it is possible to prevent the material from being hardened for the first time and making it impossible to perform the construction, and the construction time can be secured. At the time of construction, it does not harden in the mixer, and it is possible to secure a workable time corresponding to each construction method of driving and spraying.

  As described above, the rapid hardening type high toughness FRC material of the present invention and the blending method thereof can obtain a predetermined effect with the minimum curing, and as a result, the performance of the early high toughness FRC can be exhibited. Therefore, it is possible to establish a technique related to repair / reinforcement method by driving or spraying, which is effective for improving the durability of existing structures by reinforcing the rigidity, suppressing cracks, and miniaturizing cracks.

  Hereinafter, embodiments of the present invention will be described in detail. In the present invention, the material composition for obtaining the high toughness FRC material is basically the one described in Patent Document 1, but in addition to this, various admixtures, admixtures, aggregate components, etc. Is blended.

  Basically, PVA short fibers (vinylon fibers) satisfying the following [F1] are added to 1 to 3 VOL. % (13 to 39 kg / m3 in terms of weight), but the weight ratio 1 to 25% of the Portland cement as a cement preparation material is replaced with a hardened material or the like, that is, Add in the range of 1/1000 to 1/3 by cement weight ratio.

[M1] <Cement-based compounding material)
Water binder ratio: 25% or more and 80% or less Weight ratio of aggregate component and binder: 1.5 or less (including 0)
Silica content and cement weight ratio: 0.5 or less (including 0)
Unit water volume: 250-450 kg / m ³
High performance AE water reducing agent amount 30kg / m ³ or less [quickly hardwood]
Rapid hardwood to cement weight ratio: 1/1000 to 1/3 (replacement ratio 0.1% to 25%)
[F1] (Vinylon fiber)
Fiber diameter: 50 μm or less Fiber length: 5-20 mm
Fiber tensile strength: 1500-2400 MPa

  Here, among the cement-based mixed materials of [M1], normal Portland cement, moderately hot Portland cement, low heat Portland cement, early strong Portland cement and the like can be used as the binder. In addition to these Portland cements, silica-based powders (artificial pozzolans) can be used. Silica fume, fly ash, each slag powder, etc. can be applied as the silica-based powder. Therefore, in the above [M1], the “binding material” defined as water binder ≧ 25%, aggregate component and binder ratio ≦ 1.5 includes “Portland cement + silica system” when silica-based fine powder is included. It means “fine powder + quick-hardening material”. The higher the water binder ratio, the better the tensile elongation performance, and the lower the water binder ratio, the compressive strength. In order to balance both, 40% or more of the intermediate value is good.

  For materials that cause cement to set early, quick setting agents used for spraying applications that cause immediate setting are known, but materials that are generally called quick-hardening materials (agents) that have a longer setting start time are the main components. Calcium aluminate and anhydrous gypsum can be used. As such a quick hard material, for example, the trade name “Bifoam” of Denki Kagaku Kogyo Co., Ltd. is excellent in the early strength development of the high toughness FRC material, and is 1/1000 to 1/3 in terms of cement weight ratio. Mix in the range.

The amount of the hardened material is related to the early development of the compressive strength, and the compressive strength increases as the amount increases. As the compressive strength increases, fine cracks, which are the characteristics of the high toughness FRC material, are difficult to enter. Therefore, 1/1000 to 1/3 is effective for the hardened material (agent). The amount of the quick hard material (agent) that satisfies the condition is 150 g / m ^{3 to} 600 kg / m ³ .

  As the aggregate component, it is preferable to use fine particles having a maximum particle size of 0.8 mm, and those having an average particle size of 0.4 mm or less are particularly preferable. Any fine granule satisfying this condition can be used as an aggregate component such as cinnabar and limestone powder. These are preferably blended so that the weight ratio (S / C) between the fine particles and the binder is 1.5 or less.

  As the admixture, a high performance AE water reducing agent, a thickening agent, a shrinkage reducing agent and the like can be used. As the high performance AE water reducing agent, polycarboxylic acid type, polyether type, naphthalene type, melamine type, aminosulfonic acid type and the like can be used. Of these, polycarboxylic acid-based or polyether-based ones are preferable and have a track record. A known water-soluble polymer type thickener can be used. In particular, the use of a biosaccharide thickener by microbial fermentation is preferred. By adding a shrinkage reducing agent or a swelling agent, the amount of drying shrinkage can be kept small.

  PVA short fibers that satisfy the condition [F1] are preferably short fibers having an elastic modulus equal to or greater than that of concrete produced using polyvinyl alcohol resin as a raw material. When the blending amount of the PVA short fibers is less than 1 VOL%, the yield strength after cracking is not sufficient. On the other hand, when the amount of the PVA short fibers exceeds 3.0 VOL%, it becomes difficult to satisfy the fluidity necessary for construction. What is necessary is just to set it as the range of 13 kg-39 kg as a compounding quantity of the PVA short fiber in unit weight.

  The cement-based compounded material satisfying the condition of [M1] and the PVA short fiber satisfying the condition of [F1] are kneaded to produce a rapid hardening type high toughness FRC.

  For example, when kneading is carried out through the following procedures (1) to (4) and (5), the crack dispersion type having a target tensile strain of 0.2% or more in the material age from 1 day to 5 days It was found that a high toughness FRC material was obtained.

(1) Knead the binder, the hardened material, the aggregate and the mixed water.
However, in order to adjust the construction time, the hardened material is added between (2) and (3) or at the timing of (5). The construction time is secured by adding a setting retarder according to the construction conditions.
(2) Add high-performance AE water reducing agent and mix.
(3) Add a thickener and mix.
(4) Add PVA short fibers and knead.
Furthermore, (5) AE high-performance water reducing agent and rapid hardening material are added as necessary.

  That is, first, (1) a binder, a hardened material, an aggregate, and mixed water are put into a mixer and kneaded. At this time, the hardened material hardens rapidly after pouring, so if necessary, use a setting retarder to ensure the workable time, or change the addition timing of the hardened material immediately before finishing or before adding the fiber By doing this, the workable time will be secured.

  The AE water reducing agent in the procedure (2) is added to bring the mortar into a predetermined state.

  If a thickener and PVA short fibers are added and kneaded, a kneaded product in which fibers are uniformly dispersed can be obtained. However, it is more desirable to add fibers and knead after adding a thickener. This is because the viscosity of the thickener contributes to fiber dispersion. When the order is reversed, the dispersibility of the fiber becomes inferior to that of the former. First, the thickener is added and kneaded according to the procedure (3), and then the PVA fiber is kneaded according to the procedure (4). Procedure (5) is determined according to the construction conditions. In order to make the construction time as long as possible, in the case of a quick-hardened material having a high hardenability, it is added after the fibers are dispersed, and construction such as driving or spraying is performed immediately. The AE water reducing agent to be added in the procedure (5) is added in order to obtain a predetermined workability, and is added according to necessary conditions.

  A setting retarder is added to secure the construction time. The amount to be used is added in a range of 0 to 5% by weight with respect to the amount of cement and rapid hardening material. As the setting retarder, a predetermined setting retarder is used depending on the rapid hardening material to be used. What has potassium carbonate, tartaric acid, and citric acid as a main component can be used. For example, “D-300” manufactured by Denki Kagaku Kogyo Co., Ltd. can be used. The setting retarder is basically added at the same time as the rapid hardening material.

  According to the above procedure, due to the influence of the hardened material, it becomes possible to manufacture a quick-hardened high-toughness FRC material that exhibits a tensile strain performance of 0.2% or more at an early stage while securing the construction time.

  To perform the construction, either driving construction or spraying construction is possible. The construction time to be secured varies depending on the construction method.

  The rapid-hardening type high toughness FRC of the present invention is driven in immediately after being kneaded.

  Spray construction is mainly applied to vertical surfaces such as column surfaces and wall surfaces, and looking up surfaces such as beam bottoms and slab bottoms. Immediately after the rapid hardening type high toughness FRC material is prepared, spraying is performed.

  By using the rapid-hardening high-toughness FRC that exhibits tensile performance in 1 to 5 days, the excellent properties of the high-toughness FRC material can be applied to existing structures in a short curing period. Repair and reinforcement methods are possible.

(Example of test results)
The quick hardening type high toughness FRC is prepared by adding a hardened material in an amount of 1/3 to 1/999 of cement for driving. Table 2 shows the composition. It is manufactured by the procedures (1) to (4) of the manufacturing method.

  FIG. 1 shows a comparison of the tensile performance of a quick-hardening high-toughness FRC with the addition of the quick-hardening material in Table 1 on the basis of the age of one day and that of a conventional high-toughness composite material. Table 2 shows a comparison of the tensile performance of the conventional and quick-hardening type A blends and B blends.

  FIG. 1 shows a dumbbell-type test piece as shown in FIG. 2, which is directly pulled and shows the strain of the test piece and the stress applied to the cross section at that time.

  The larger the area surrounded by the figure drawn by the graph of FIG. 1 and the X axis, the higher the deformation performance and toughness. Tensile performance is a region where the strain is larger than the yield point. The ultimate strain is the point where the tensile yield strength reaches the same value. The larger the value, the better the tensile deformation performance. The target value is 0. .2% or more. The ultimate strain was 8.2% for the A composition and 7.6% for the B composition at a material age of 1 day, indicating a very excellent value.

  The time after post-processing of the rapid hardening type high toughness FRC material (hereinafter referred to as “C”) increased by 0.2% (the amount of cement per unit amount) of the setting retarder of “A” and the high toughness FRC material of “A” Table 3 below summarizes the properties.

  As shown in Table 3, the construction time can be extended by 10 minutes, and the construction time can be secured with a setting retarder.

  FIG. 3 is an example showing the initial and final setting times of a conventional high toughness FRC and a rapid hardening high toughness FRC containing A.

  As can be seen from FIG. 3, the conventional high toughness FRC has a large amount of additive admixture, so that it is often hard to demold in one day. In the conventional high toughness FRC, sufficient curing time is required to exhibit performance.

  4, 5, and 6 show the rapid hardening type when the addition amount of the rapid hardening material is further reduced to 1/999 of the rapid hardening material with respect to the cement (weight ratio D). The properties of the high toughness FRC and the conventional high toughness FRC are compared.

  FIG. 4 shows the slump flow value and changes with time as the properties at the time of fresh. FIG. 5 shows an example of compression test results and tensile performance at ages 1, 2, and 3 days as properties after curing of the D blend. There was no significant difference in tensile yield strength at one day of age, but an effect on tensile strain was observed. Moreover, the effect was recognized also with respect to compressive strength.

It is the graph which compared the tensile performance of the quick hardening type high toughness FRC material age 1 day, and the tensile performance of the conventional high toughness composite material. It is explanatory drawing which shows a tension test method. It is the graph which showed the setting start time and the end time of the conventional high toughness FRC and the rapid hardening type high toughness FRC of A composition. Table 1 shows the elapsed time from the blending of A blend and B blend and the properties of the material at that time. When the addition amount of the rapid hardening material is reduced so that the addition amount of the rapid hardening material is 1/999 with respect to the cement (weight ratio D), the rapid hardening type high toughness FRC and the conventional high toughness FRC FIG. 6 is a graph showing the slump flow value and the change over time as the fresh properties. When the addition amount of the rapid hardening material is reduced so that the addition amount of the rapid hardening material is 1/999 with respect to the cement (weight ratio D), the rapid hardening type high toughness FRC and the conventional high toughness FRC It is a graph which shows the compression test result in material age 1, 2, and 3 days. When the addition amount of the rapid hardening material is reduced so that the addition amount of the rapid hardening material is 1/999 with respect to the cement (weight ratio D), the rapid hardening type high toughness FRC and the conventional high toughness FRC It is the graph which compared the property of, and showed the tensile performance in material age 1 day.

Claims (3)

  Calcium aluminate and anhydrous gypsum for the cement to be used in the cracked dispersion type high toughness FRC material in which short fiber of PVA is blended in cementitious compounding material and shows tensile strain of 0.2% or more in tensile test Add 1/1000 to 1/3 by weight ratio of the quick-hardened material containing as a main component, and satisfy the required value of tensile strain of 0.2% or more in the tensile test at the age of 1 to 5 days. A quick-hardening high-toughness FRC material characterized by   Calcium aluminate and anhydrous gypsum for the cement to be used in the cracked dispersion type high toughness FRC material in which short fiber of PVA is blended in cementitious compounding material and shows tensile strain of 0.2% or more in tensile test When adding 1/1000 to 1/3 by weight ratio of the quick-hardening material containing as a main component, first, a setting retarder and blended water are added to the mixer together with the binder, aggregate, and quick-hardening material. A quick-hardening type characterized by mixing or mixing with a mixer, aggregate and blended water in a mixer, and then adding a quick-hardening material immediately before kneading and before adding fibers Manufacturing method of high toughness FRC material.   Calcium aluminate and anhydrous gypsum for the cement to be used in the cracked dispersion type high toughness FRC material in which short fiber of PVA is blended in cementitious compounding material and shows tensile strain of 0.2% or more in tensile test A method for preparing a quick-hardening high-toughness FRC material, comprising adding 1/1000 to 1/3 by weight ratio of a quick-hardening material containing as a main component and adding a setting retarder together with the quick-hardening material.

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