JP2008044841A - Binder composition for ultra-high strength concrete and concrete composition using the same, and concrete product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultra-high strength concrete composition having excellent compressive strength and bending strength. <P>SOLUTION: The ultra-high strength concrete binder composition contains 90-95 pts.wt. cement mixture and 5-10 pts.wt. silica fume, the cement mixture containing 80-96 pts.wt. clinker mainly made up of 4CaO-3Al<SB>2</SB>O<SB>3</SB>-SO<SB>3</SB>and 4-20 pts.wt. anhydrous gypsum. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a binder composition for early-strength ultra-high-strength concrete excellent in bending strength, a concrete composition using the same, and a concrete product. Specifically, clinker mainly containing _{4CaO · 3Al 2 O 3 · SO} 3, concrete binder composition comprising anhydrite and silica fume at a predetermined ratio, the concrete composition using the same and by using this It relates to a concrete product to be manufactured.

  Concrete manufactures various structures by mixing aggregate with cement paste, and the paste plays an important role in strength development as well as bonding and bonding the aggregate and aggregate. However, concrete produced using ordinary cement paste and aggregate has high compressive strength, but it has low tensile strength and bending strength, and the material is expensive or has a long curing period, so productivity and economy are problematic. ing.

  For example, although a general concrete manhole manufactured by using the above-described ordinary method is inexpensive, the bending strength is remarkably lower than the compressive strength, so it is necessary to express the bending strength using a reinforcing bar. For this reason, the thickness of the cross section becomes thick and the weight increases, making it difficult to handle. Especially, as a result of increasing the width of digging, it is difficult to use in a city center with many obstacles.

  In order to solve the problems of low tensile strength and bending strength as described above, recently, polymer concrete using a resin such as polyester without using cement paste as a binder for concrete, or steel fiber and ordinary cement paste, Fiber reinforced concrete produced by mixing organic fibers or the like is used in structures that require high bending strength and compressive strength.

  Polymer concrete not only has higher physical properties such as compression, tensile and bending strength than general cement concrete, but also has excellent characteristics that can widely control pot life and setting time. However, polyester resins and the like used for polymer concrete materials are approximately expensive, and there is a problem that the price increases with the international oil price and the supply and demand situation of raw materials.

  Fiber reinforced concrete has solved the problems of low tensile and bending strength that concrete has, but the curing temperature is high, the curing time is long, the dispersion effect is not excellent, and expensive reinforcing fibers need to be mixed. Therefore, there are problems in terms of productivity and economy.

Korean Patent No. 2001-0071263 (Patent Document 1) discloses a method of increasing bending strength by blending sand, quartz powder, silica fume, dispersant, organic fiber, etc. with ordinary Portland cement. Has been. However, in order to express a predetermined bending strength, it is necessary to mix the curing at 90 ° C. for 2 days and an expensive material such as organic fiber or steel fiber, which has problems in productivity and economy. In addition, the range of use is limited except that it is used for some special structures.
Korean open patent 2001-0071263

  The present invention has been devised to solve the above-mentioned problems, and it is possible to reduce the temperature and time of steam curing, and without using a resin such as polyester or reinforcing fibers, polymer concrete or fiber-reinforced ultra-high-strength concrete. Thus, the present invention provides ultra-high-strength concrete having good compressive strength and bending strength.

The present inventors have result of extensive studies for solving the above _{problems, 4CaO · 3Al 2 O 3 ·} SO 3 as main components clinker 80 to 96 parts by weight and a cement mixture containing anhydrite 4-20 parts by weight The concrete binder composition comprising 90 to 95 parts by weight and 5 to 10 parts by weight of silica fume reduces the steam curing temperature and time, and at the same time, produces an ultra high strength concrete having not only compressive strength but also good bending strength. The present invention was completed by obtaining the knowledge that it can be obtained.

Accordingly, the present invention is a concrete binder composition,
Comprising 90 to 95 parts by weight of cement mixture, and 5 to 10 parts by weight of silica fume, based on the total weight of the concrete binder composition;
The cement mixture, relative to the total weight of the cement mixture, comprising clinker composed mainly of _{4CaO · 3Al 2 O 3 · SO} 3 in 80 to 96 parts by weight, and anhydrite 4-20 parts by weight Is.

[The invention's effect]
The present invention does not exist in the prior art by setting the cement mixture and silica fume to a specific weight part ratio, and setting the weight ratio of the clinker and anhydrous gypsum constituting the cement mixture to a specific numerical range, respectively. It exhibits an excellent effect. Specifically, according to the present invention, steam curing temperature and time can be reduced, and not only compressive strength but also bending can be achieved, such as polymer concrete or fiber reinforced ultra high strength concrete without using resin such as polyester or reinforcing fiber. It is possible to economically provide ultra-high strength concrete having good strength. In addition, the ultra-high-strength concrete manhole manufactured using the concrete binder composition according to the present invention has various structures that require high structural strength (including bending strength) instead of existing expensive polymer concrete or fiber-reinforced concrete. It can be applied to an object (for example, a manhole for optical communication).

I. Concrete binder composition The concrete binder composition according to the present invention comprises 90 to 95 parts by weight (preferably 92.5 to 95 parts by weight) of a cement mixture, based on the total weight of the concrete binder composition, And 5 to 10 parts by weight (preferably 5 to 7.5 parts by weight) of silica fume.

Cement mixture The cement mixture is a clinker composed mainly of 80 to 96 parts by weight (preferably 90 to 96 parts by weight) of 4CaO.3Al ₂ O ₃ .SO ₃ with respect to the total amount of the cement mixture, and 4 to 20 parts by weight (preferably 4 to 10 parts by weight) of anhydrous gypsum.

In the present invention, when anhydrous gypsum is contained in less than 4 parts by weight with respect to the total amount of the cement mixture (that is, clinker containing 4CaO.3Al ₂ O ₃ .SO ₃ as a main component is contained in excess of 96 parts by weight). In the case where ettringite is not sufficiently produced early, it is difficult to develop early strength, and when gypsum exceeds 20 parts by weight with respect to the total amount of the cement mixture (that is, 4CaO · 3Al ₂ O ₃ · In the case where the clinker mainly containing SO ₃ is contained in less than 80 parts by weight, ettringite crystals are further entangled and firmly bonded to each other, and ettringite is further formed. As the time increases), the range of decrease in bending strength increases. On the other hand, when the anhydrous gypsum is 4 to 20 parts by weight as in the present invention, the ettringite crystals are optimally produced, the bending strength of the concrete is very high, and even if the age period increases, the bending strength changes or It has the advantage that the width of the reduction is small. In particular, in order to maximize the bending strength, the content ratio of anhydrous gypsum is preferably 4 to 10 parts by weight.

Ordinary Portland cement produces calcium silicate (Calcium Silicate) plate-like crystals, so it shows less bending strength than compressive strength, and has used a separate fiber reinforcement to increase bending strength. For overcoming such a drawback, the present invention is the main hydrated products of gypsum and clinker (CSA cement) composed mainly of _{4CaO · 3Al 2 O 3 · SO} 3 ettringite (Ettringite) of the needle crystals The bending strength is increased without reinforcing the fiber by utilizing the intertwisting structure. The ettringite needle-like crystal generally means a crystal component produced through a hydration reaction when both CSA cement and anhydrous gypsum meet with water. That is, ettringite needle-like crystals are formed in the process in which a cement mixture containing CSA cement and gypsum is mixed with water together with fine aggregate and coarse aggregate to form a concrete composition, then cured, dried and finished into a concrete product. It is.

1) In the clinker present invention, the term "clinker", be one composed mainly of _{4CaO · 3Al 2 O 3 · SO} 3, particularly limited as long as components capable of producing ettringite needle crystals not, for example, a clinker consisting _{4CaO · 3Al 2 O 3 · SO} 3 clinker consisting solely or _{4CaO · 3Al 2 O 3 · SO} 3 or 2CaO · SiO _2,. Also, clinker for the _{4CaO · 3Al 2 O 3 · SO} 3 in the present invention as a main component (e.g., CSA cement) can be prepared by methods well known in the art to which the invention pertains. For example, a clinker containing only 4CaO · 3Al ₂ O ₃ · SO ₃ can be obtained by mixing bauxite, limestone, and gypsum, and then firing the mixture at 1200 to 1300 ° C. for about 2 hours. .

  In the present invention, since the “clinker” capable of generating ettringite needle-like crystals is used, the dense entanglement of the slender ettringite needle-like crystals plays a role of increasing the bending strength. It is possible to produce ultra-high-strength concrete without adding the fiber reinforcement.

  In the present invention, in order to maximize the bending strength, the ettringite crystals are formed so as to be closely entangled with each other in an elongated needle shape, and after the ettringite needle crystals are entangled and bonded to each other, the ettringite crystals are further formed. It is necessary to prevent the ettringite crystal structure that is produced and tightly entangled from breaking and bending strength from decreasing. After curing, the continuous generation of ettringite crystals makes the cured body more dense and the compressive strength is increased, but the entanglement of the ettringite needle-shaped crystals is broken, resulting in a decrease in the bending strength.

  A cement / concrete composition using a material from which a normal ettringite crystal is formed considers only the early strength and the compressive strength, and has a limit to application to a structure requiring high bending strength. However, in the present invention, since a specific “clinker” is used, it is possible to provide an ultra-high-strength concrete binder composition that overcomes such conventional problems.

2) Anhydrous gypsum In the present invention, "anhydrous gypsum (CaSO ₄ )" is a component that may be used in the production of ordinary cement. In general, gypsum is present in the form of dihydrate gypsum (CaSO ₄ .2H ₂ O) at room temperature, but it is dehydrated in the range of about 80 to 150 ° C. due to accumulation of heat energy or an increase in ambient temperature, and so on. -CaSO ₄ · 1 / 2H ₂ O) and secondary dehydration in the range of 105 to 240 ° C., anhydrous gypsum (type III) (CaSO ₄ ), and tertiary dehydration in the range of 230 to 350 ° C. When it occurs, it becomes anhydrous gypsum (type II) (CaSO ₄ ), and when it undergoes quaternary dehydration in the range of about 1150 to 1200 ° C., it becomes anhydrous gypsum (type I) (CaSO ₄ ). In the present invention, the hydrated gypsum is not particularly limited as long as it can form an ettringite crystal, and the type II anhydrous gypsum widely used in the production of cement is preferably used in terms of economy and availability. it can.

Silica fume The present invention comprises 5 to 10 parts by weight (preferably, 5 to 7.5 parts by weight) of silica fume based on the total weight of the concrete binder composition.

When the silica fume is replaced by less than 5 parts by weight, the workability is drastically reduced at a low water-cement ratio, and when the silica fume is replaced by more than 10 parts by weight, the bending strength is lowered. On the other hand, when the silica fume is 5 to 10 parts by weight as in the present invention, the fluidity of the concrete composition is optimized, the mixing is performed well, the moldability is increased, and the concrete compressive strength and bending strength are maximized. .

  In the present invention, silica fume may be an ultrafine particle and is a preferred form as an admixture. The ultrafine silica fume is preferably spherical particles having a particle size of 0.1 to 1 μm. By mixing such an ultrafine silica fume in an appropriate amount, the mixing amount of water is reduced to improve the workability, and the fine pores are filled to make the structure dense and improve the strength.

According to a preferred embodiment of the present invention, a clinker (CSA cement) based on 80 to 96 parts by weight of 4CaO.3Al ₂ O ₃ .SO ₃ as a main component and 4 to 20 parts by weight for high bending strength. It is possible to propose a concrete binder composition in which one in a cement mixture (100 parts by weight) containing anhydrous gypsum is replaced with 5 to 10 parts by weight of silica fume.

II. Concrete Composition According to the present invention, it is possible to propose a concrete composition including the concrete binder composition and a suitable fine aggregate such as quartz sand.

The content of fine aggregate fine aggregate, the is preferably a concrete binder composition 100 parts by weight per fine aggregate 100-175 parts by weight, 100 to 150 parts by weight in order to maximize the high bending of the concrete It is more preferable that The fine aggregate is preferably quartz sand having a maximum particle size of 5 mm or less.

Optional Additives The concrete composition may further comprise blended water, coarse aggregate (described below), or a high performance water reducing agent. A concrete composition obtained by adding such a material or a concrete product (including a test specimen) obtained therefrom can be produced. Here, the content of the blended water is not particularly limited, but in order to prevent a decrease in the structural strength of the concrete structure such as the compression and bending strength of the concrete manhole, 20 parts by weight with respect to 100 parts by weight of the binder composition. It is preferable that: In addition, high performance water reducing agents are added to compensate for compression and bending strength while minimizing the water ratio and maintaining workability.

III. Concrete Product and Manufacturing Method Thereof The concrete product (including the specimen) according to the present invention can be manufactured by various methods, for example, clinker mainly composed of 4CaO · 3Al ₂ O ₃ · SO ₃ A binder composition produced by mixing 90 to 95 parts by weight of a cement mixture containing 80 to 96 parts by weight and 4 to 20 parts by weight of anhydrous gypsum, and 5 to 10 parts by weight of silica fume, and the binder composition Mixing a fine aggregate (silica sand) of 100 to 175 parts by weight with a maximum particle size of 5 mm or less, 100 parts by weight of the binder composition and 20 parts by weight or less of the blended water and a high-performance water reducing agent with a forced mixer; It can be manufactured by a manufacturing method including a curing stage.

  The curing stage is 30 minutes to 2 hours in advance, steam curing at 40 ° C. or lower for 2 hours to 4 hours (primary curing), steam curing at 50 ° C. to 90 ° C. for 6 hours to 22 hours (secondary curing), 1 to It can be performed by performing a six-day wet curing (tertiary curing). In particular, the concrete composition according to the present invention, apart from the conventional concrete composition, can exhibit high compressive strength and bending strength even when steam-cured at a relatively low temperature for a short time. There is an advantage that a structure can be manufactured.

  Under the above curing conditions, in order to produce ettringite crystals to the maximum, the steam curing time is set to 12 hours to 24 hours, particularly at 40 ° C. or less for 2 hours to 4 hours (primary curing), at 50 ° C. to 90 ° C. It is preferable to set the steam curing for 6 hours to 22 hours (secondary curing). If the secondary steam curing time is less than 6 hours, the ettringite needle-like crystals are not formed in a relatively dense manner, resulting in a decrease in the bending strength due to the formation of additional ettringite after curing. If the curing time exceeds 22 hours, ettringite crystals are not further formed, and therefore an additional strength enhancement effect is not exhibited.

  Furthermore, various concrete products (structures) such as concrete manholes can be produced from a composition obtained by further adding coarse aggregate to the concrete composition. Here, the bending strength of the concrete structure decreases as the coarse aggregate particle size increases, but in the case of a concrete structure such as a manhole, the thickness is as thin as about 5 cm, so a small particle size of 10 mm or less. It is preferable to use the coarse aggregate.

  Super high-strength concrete manholes must be not only economical but also productive, but according to the applicant's experiments, steam at temperatures below 40 ° C for 30 minutes to 1 hour and for 2 to 3 hours By performing curing, the mold can be rotated twice a day. By performing steam curing at 60 ° C to 70 ° C for 12 to 20 hours, curing can be performed at a relatively low temperature within one day. The energy cost can be minimized and the structure can be completed through a process of stabilizing the manhole through steam or wet curing at room temperature for 1 to 2 days. FIG. 5 is a diagram schematically illustrating a method for manufacturing and curing such a structure.

[Example]
Hereinafter, the present invention will be described in detail through examples.

  The “parts by weight”, “weight ratio”, and “wt%” used as content units in the present invention represent relative contents as in the following embodiments, Even if the reference content is not explicitly stated, one skilled in the art to which the present invention pertains has no difficulty in determining the relative content of each component of the present invention.

[Example 1]
Cement obtained by mixing clinker (CSA cement) of 4CaO · 3Al ₂ O ₃ · SO ₃ component and type II anhydrous gypsum in weight ratios of 95: 5, 90:10, 85:15, 80:20 and 75:25, respectively. 92.5 parts by weight of the mixture and 7.5 parts by weight of silica fume were mixed to produce a binder composition, and the sand was mixed so that the ratio of 100 parts by weight of the binder composition to 100 parts by weight of the specific sand was 100 parts by weight. The concrete composition was manufactured so that the weight ratio of the blended water containing the high-performance water reducing agent and the binder composition was 18%. This composition was mixed with a mixer for 5 minutes to prepare a test specimen, which was pre-set for 1 hour, subjected to primary steam curing at 40 ° C. for 3 hours, and secondary steam curing at 70 ° C. for 20 hours, and then 2 days each. A concrete specimen was prepared by wet curing for 6 days, and the bending strength and compressive strength of the specimen were measured according to KS L 5207. The results are shown in Table 1 and FIG.

[Example 2]
In Example 1, the weight ratio of clinker (CSA cement): gypsum was fixed at 95: 5, and the weight ratio of cement mixture: silica fume was 95: 5, 92.5: 7.5, 90:10 and 85: Except for the point changed to 15, a binder composition and a concrete composition were produced in the same manner as in Example 1. The bending strength and the compressive strength were also measured according to KS L 5207 for a concrete test body manufactured through curing in the same manner as in Example 1. The results are shown in Table 2 below and FIG.

[Example 3]
In Example 1, the weight ratio of clinker (CSA cement): gypsum was fixed to 95: 5, and 100 parts by weight of sand, 100 parts by weight, 125 parts by weight, 150 parts by weight, and 175 parts by weight, respectively. A binder composition and a concrete composition were produced in the same manner as in Example 1 except that sand was mixed. The bending strength and the compressive strength were also measured according to KS L 5207 for a concrete test body manufactured through curing in the same manner as in Example 1. The results are shown in Table 3 below and FIG.

[Example 4]
In the setting of the steam curing temperature and time in Example 1, secondary steam curing is performed at 40 ° C., 50 ° C., 60 ° C., 70 ° C., 80 ° C. and 90 ° C. for 8 hours or 20 hours, or 90 ° C. for 44 hours. Except for the points, a binder composition and a concrete composition were produced in the same manner as in Example 1. The bending strength and the compressive strength were also measured according to KS L 5207 for a concrete test body manufactured through curing in the same manner as in Example 1. The results are shown in Table 4 below and FIG.

[Example 5]: Production of ultra-high-strength concrete manhole A concrete manhole composition was produced at the composition ratio shown in Table 5 below. That is, a binder containing 92.5% by weight of a cement mixture containing 96% by weight of clinker based on 4CaO · 3Al ₂ O ₃ · SO ₃ and 4% by weight of type II anhydrous gypsum, and 7.5% by weight of silica fume. Composition for ultra high strength concrete manhole by adding 120 parts by weight of total binder to which 20 parts by weight of blended water is added per 100 parts by weight, 110.8 parts by weight of fine aggregate, and 138.5 parts by weight of coarse aggregate Manufactured.

Evaluation test Using the composition of Table 1 above, a communication having internal dimensions of 1.2 m in width, 1.8 m in height and 1.9 m in length, and a thickness of 10 cm at the top, 10 cm at the bottom and 5.5 cm at the wall. Manhole (Hikari Manhole No. 3) was manufactured, pre-cured for 1 hour, steam-cured (primary curing) at 40 ° C for 3 hours, removed from the mold to avoid cracks, and 70 ° C for 20 hours After steam curing (secondary curing), a concrete manhole structure was manufactured through a compress curing (tertiary curing) at room temperature for 1 day, and a structural experiment was performed three days later by the following procedure.

  As sensors to detect the presence or absence of cracks, six deformation rate gauges around the upper slab circular opening and three deformation rate gauges around the lower slab water mouth are attached, and a large iron lid (φ918) is attached to the upper slab. Using a loading plate having a width of 20 cm and a length of 50 cm, the load at the time when a crack occurred was measured while loading a load of 1 ton every 30 seconds. FIGS. 6a and 6b are views showing an upper part and a lower part inside a manhole structure in a structure experiment of an ultra-high-strength concrete manhole, respectively, and (1) to (9) are sensors of the structure experiment. Indicates the mounting position. Further, FIGS. 6c and 6d are photographs showing a scene where a structural experiment is performed using such a manhole structure, and FIG. 7 is a graph showing measurement data of the structural experiment of the manhole as a result.

  As a result of structural experiments, it was confirmed that no cracks occurred up to a load (37.44 tons) that reached three times the DB-24 load including the impact (load of one wheel 9.6 tons, impact coefficient 0.3). The excellent performance of the super high strength concrete manhole was confirmed.

  For reference, the case of a manhole manufactured using fiber reinforced concrete added with 1.5% steel fiber by volume and polymer concrete using polyester as a binder component is also similar to the concrete manhole according to the present invention. No cracks occurred up to the level load (approximately 40 tons).

  That is, the concrete manhole according to the present invention and the conventional steel fiber reinforced concrete manhole or polymer concrete are all excellent in strength such as bending strength so that no cracks are generated up to three times the DB-24 load. Manholes have the advantage that there are no corrosion problems in the case of steel fiber reinforced concrete manholes and no problem of economic deterioration in polymer concrete manholes.

It is a figure which shows the result of the bending strength of concrete accompanying the ratio change of gypsum. It is a figure which shows the result of the bending strength of concrete accompanying the ratio change of a silica fume. It is a figure which shows the result of the bending strength of concrete accompanying the ratio change of a fine aggregate. It is a figure which shows the result of the bending strength of concrete accompanying the change of steam curing time and temperature. It is the schematic which shows the manufacturing method of the super high-strength concrete manhole which concerns on this invention. It is a photograph which shows the scene of the structural experiment of the ultra high strength concrete manhole which concerns on this invention. It is a photograph which shows the scene of the structural experiment of the ultra high strength concrete manhole which concerns on this invention. It is a photograph which shows the scene of the structural experiment of the ultra high strength concrete manhole which concerns on this invention. It is a photograph which shows the scene of the structural experiment of the ultra high strength concrete manhole which concerns on this invention. It is a graph which shows the measurement result of the structural experiment of the ultra high strength concrete manhole which concerns on this invention.

Explanation of symbols

1-9: Sensor mounting position in the structural experiment of ultra high strength concrete manhole

Claims (6)

Comprising 90 to 95 parts by weight of cement mixture and 5 to 10 parts by weight of silica fume, based on the total weight of the concrete binder composition;
The cement mixture, relative to the total weight of the cement mixture, comprising clinker composed mainly of _{4CaO · 3Al 2 O 3 · SO} 3 in 80 to 96 parts by weight, and anhydrite 4-20 parts by weight , Concrete binder composition.   A concrete composition comprising the concrete binder composition according to claim 1 and a fine aggregate.   The concrete composition according to claim 2, wherein the fine aggregate is included in an amount of 100 to 175 parts by weight with respect to 100 parts by weight of the concrete binder composition.   The concrete composition according to claim 2 or 3, further comprising a coarse aggregate.   A concrete product produced by a method comprising steam curing the concrete composition according to claim 2 or 3 at 40 ° C or lower for 2 to 4 hours and 50 ° C to 90 ° C for 6 to 22 hours. . Preceding the concrete composition according to claim 4 between 30 minutes and 1 hour,
Steam curing at 40 ° C. or lower for 2 to 3 hours, steam curing at 60 ° C. to 70 ° C. for 12 to 20 hours, and steam or wet curing at room temperature for 1 to 2 days An ultra-high-strength concrete structure manufactured by a method comprising: