JP5610568B2 - Method for producing hydrated hardened body using fine aggregate made of steel slag - Google Patents

Description

The present invention relates to the production how hydrated hardened body using fine aggregate consisting of steel slag.

  Slag (blast furnace slag and steelmaking slag) generated in the iron making process is expected to be used for civil engineering and building materials from the viewpoint of reducing the amount of industrial waste discarded and from the characteristics of high density and hardness. Blast furnace slag has a relatively stable chemical composition and is less likely to expand as described below, and therefore is used relatively easily in aggregates of hydrated hardened bodies such as concrete and mortar. On the other hand, the steelmaking slag has a problem that quick lime (free lime) remains and the free lime reacts with water and expands, causing cracks in the hydrated hardened body and reducing the strength. It is said that it is difficult to use for the aggregate of a Japanese hardened body.

  Therefore, in order to effectively use the steelmaking slag, various techniques for suppressing the volume expansion of the steelmaking slag that causes cracking have been proposed. Patent Document 1 proposes that an aging treatment for suppressing volume expansion of steel slag is performed in a short time by using steam.

JP 2007-106631 A

  However, in the said patent document 1, it is a premise to perform an aging process, and the utilization method of the steelmaking slag described in the said literature cannot be said to be the utilization method using the characteristic of steelmaking slag.

An object of the present invention, together can be omitted the free lime removal process including aging process, while utilizing the characteristics of the steel slag that can alleviate the cracking problem, hydrated hardened body using fine aggregate consisting of steel slag it is to provide a manufacturing how.

  The present inventors do not remove the free lime as in the above aging treatment and suppress the expansion characteristics of the steelmaking slag, but positively utilize the expansion characteristics of the free lime and the steelmaking slag resulting therefrom. Focused on. And based on such attention, as a result of experiment and consideration using various examples and comparative examples as described later, the following invention has been provided in order to achieve the above object.

According to an aspect of the present invention, the fine aggregate and the fine aggregate consisting of steel slag with a separate fine aggregate, water and cement and curing step of curing by mixing to hydration reaction, hydration A method for producing a hardened body, which is a steelmaking slag produced by a steelmaking process as a method for producing a fine aggregate made of the steelmaking slag, and is an aging treatment, air crushing treatment, chemical reaction promotion by addition of additives The crushing process which crushes the steelmaking slag in which the free lime removal process for removing the free lime which remains in the said steelmaking slag including a process and carbonation treatment is not performed, and the steelmaking slag crushed in the said crushing process the, as those 10mm sieve through all and the following particle size 5mm is 85% or more by weight, and a particle size control step of particle size control for fine aggregate, in the curing step, the particle size adjustment And wherein the dispersing placed in the hydration hardening body size adjusted consisting steel slag fine aggregate, in a condition, respectively volumetric expansion in step, the manufacturing method of the hydrated cured product is provided.

  Here, the “free lime removal treatment” means various treatments for removing free lime remaining in the steelmaking slag generated by the steelmaking process. For example, “free lime removal treatment” includes aging treatment (natural aging treatment in which the hydration reaction of free lime is allowed to proceed outdoors for a long time, and hydration reaction of free lime in a short period of time using steam or hot water. Steam or hot water aging treatment, etc.), air crushing treatment (treatment of rapidly solidifying molten steelmaking slag with a high-speed air flow), additives (coal ash, substances having reactivity with porazone (silica etc.), granulated slag powder , Gypsum, CaCl 2, granulated blast furnace slag, etc.), chemical reaction promotion treatment, carbonation treatment (treatment of returning free lime to the natural limestone state by reacting with carbon dioxide), and the like.

According to the manufacturing method of the above Symbol view point, disrupting the steelmaking slag Yu away lime removal process is not crack line, followed by carrying out the particle size adjustment step, to produce a fine aggregate consisting of steel slag. The fine aggregate made of steelmaking slag thus produced is less likely to crack due to volume expansion when applied to a hydrated hardened body such as mortar as will be shown later in Examples. That is, according to the manufacturing method which concerns on the said viewpoint, while being able to abbreviate | omit the free lime removal process including an aging process, the problem of a crack can be reduced, utilizing the characteristic of steelmaking slag.

In the crushing step, the free lime contained in the prior SL steelmaking slag into fine particles in the particle size adjustment step, may be a particle size adjusted to include the micronized free lime in the crushing step as fine aggregate .

It is process drawing which shows one Embodiment of the manufacturing method of the fine aggregate which consists of steelmaking slag in the manufacturing method of the hydration hardening body which concerns on this invention. It is a graph which shows the example of the particle size distribution in the fine aggregate adjusted in the particle size adjustment process of FIG. It is a graph which shows the bleeding rate of the mortar specimen which concerns on each Example and comparative example of this invention. It is a graph which shows the length change rate of the mortar specimen which concerns on each Example and comparative example of this invention. It is a bar graph which shows the intensity | strength of the mortar specimen which concerns on each Example and comparative example of this invention, (a) shows bending strength, (b) shows compressive strength. It is explanatory drawing for demonstrating the mechanism which concerns on this invention, (a) used the steelmaking slag as an aggregate, without performing a crushing process etc., (b) performed the crushing process etc. which concern on this invention The internal situation of the hydrated hardened body when a fine aggregate made of steelmaking slag is used is schematically shown.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

First, with reference to FIG. 1, one Embodiment of the manufacturing method of the hydration hardening body based on this invention is described.

In the method for producing a hydrated cured body according to the present embodiment, first, in producing a fine aggregate made of steelmaking slag , steelmaking slag generated by a steelmaking process is acquired (S1). As the steelmaking slag, various slags generated in the steelmaking process such as converter slag, electric furnace slag, kneading pretreatment slag, kneading furnace slag, and the like can be applied.

  And steelmaking slag acquired by S1 is crushed immediately, for example using a horizontal brown grinder (Yoshida Seisakusho), without performing a free lime removal process (S2: crushing process). Here, the “free lime removal treatment” means various treatments for removing free lime remaining in the steelmaking slag generated by the steelmaking process. For example, “free lime removal treatment” includes aging treatment (natural aging treatment in which the hydration reaction of free lime is allowed to proceed outdoors for a long time, and hydration reaction of free lime in a short period of time using steam or hot water. Steam or hot water aging treatment, etc.), air crushing treatment (treatment of rapidly solidifying molten steelmaking slag with a high-speed air flow), additives (coal ash, substances having reactivity with porazone (silica etc.), granulated slag powder , Gypsum, CaCl 2, granulated blast furnace slag, etc.), chemical reaction promotion treatment, carbonation treatment (treatment of returning free lime to the natural limestone state by reacting with carbon dioxide), and the like.

Thereafter, the steelmaking slag crushed in S2 is screened and the like, and the particle size is adjusted for fine aggregate (S3: particle size adjusting step). Herein, "particle size control for fine aggregate", will have that one thing 0mm sieve through all and the following particle size 5mm to particle size adjusted to be 85% or more by weight. FIG. 2 is a graph showing an example of the particle size distribution in the fine aggregate whose particle size is adjusted in S3.

  Thus, most of the fine aggregates manufactured through the steps S1 to S3 have a particle size of 5 mm or less (see FIG. 2).

  In the method for producing a hydrated cured body according to the present embodiment, the fine aggregate produced through the steps S1 to S3 as described above, fine aggregate different from the fine aggregate, water, and cement are mixed. Then, mortar as a hydrated cured product is produced by curing by hydration reaction.

  The “other fine aggregate” means a fine aggregate different from the fine aggregate produced from the steelmaking slag by the production method according to the present invention, for example, a natural aggregate that can be collected from a river forest or the like And recycled aggregates. As the cement, arbitrary materials such as ordinary Portland cement and various mixed cements can be applied. In the mixing step, admixtures (AE agent, water reducing agent, AE water reducing agent, etc.) may be appropriately added. The kneading method, casting / forming method, curing method, etc. are arbitrary. The ratio of aggregate, water and cement can also be set arbitrarily.

According to the manufacturing method of the hydrated cured product according to the present embodiment described above, the free lime removal process to crush the steelmaking slag is not crack line (S2: crushing step), to thereafter perform the particle size adjusting step (S3) To produce a fine aggregate made of steelmaking slag . And according to the method for producing a hydrated cured body according to the present embodiment using the fine aggregate made of steelmaking slag thus produced, as shown in the examples later, it is difficult to crack due to volume expansion. It becomes. That is, according to the production method of engaging Ru hydrated hardened body to the present embodiment, it is possible to omit the free lime removal process including aging process, while utilizing the characteristics of the steel slag, it is possible to reduce the cracking problems it can.

  Conversely, the fine aggregates having relatively small particle diameters dispersed and arranged in the hydrated cured body each undergo volume expansion, thereby suppressing the drying shrinkage of the hydrated cured body as will be shown later in the examples ( (See FIG. 4).

  In addition, according to the present invention, the effect of lowering the neutralization rate of the hydrated and hardened body is expected by the fine aggregate made of steelmaking slag having a small particle size. “Neutralization” refers to a phenomenon in which a hydrated cured body that becomes alkaline due to the influence of cement components loses its alkalinity and is neutralized by the ingress of carbon dioxide gas from the outside. The neutralization of reinforced concrete causes corrosion of the reinforcing bars inside. According to the present invention, it is not necessary to take measures to prevent neutralization (in reinforced concrete, such as increasing the cover (distance from the surface of the reinforcing bar to the surface of the concrete)), and the reinforced concrete can be made compact. .

  Next, the present invention will be specifically described with reference to examples.

  The present inventors have provided a mortar with a replacement rate of 0% as a comparative example (that is, when the fine aggregate according to the present invention is not used and all the fine aggregates are fine aggregates having the above different composition). Using a specimen and mortar specimens with substitution rates of 10%, 30% and 50% as three examples of the present invention (first, second and third examples), the bleeding rate (see FIG. 3) ), Length change rate (see FIG. 4), and strength (see FIG. 5).

  Table 1 below shows various characteristics of the fine aggregate (the fine aggregate produced by the method of the above-described embodiment) according to the present invention and another fine aggregate used in the experiment.

  Table 2 below shows the formulation (mixing ratio) of the mortar specimens according to the comparative example and each example. The replacement rate (%) is a percentage with respect to the volume of the fine aggregate as a whole, rounded down to the first digit.

  FIG. 3 is a graph showing the bleeding rate of the mortar specimens according to the comparative example and each example. Bleeding refers to a phenomenon in which water separates and rises after placing and floats on the upper surface of the cured body, and the bleeding rate refers to the ratio of the water (bleeding water) to the mass of water in the test sample. Here, for the comparative example and each example, respective bleeding rates after 3 hours and 20 hours from the placement are shown. In calculating the bleeding rate, bleeding water was sucked with a pipette, and the amount of the water was measured using a 20 ml graduated cylinder.

  From the graph of FIG. 3, it can be seen that the bleeding rate decreases as the replacement rate increases, and that the bleeding rate decreases as time elapses from placement.

FIG. 4 is a graph showing the rate of change in length of the mortar specimens according to the comparative example and each example. The vertical axis of the graph shows the shrinkage strain, and the horizontal axis shows the age when 48 hours have passed since the placement (that is, when the measurement of the shrinkage strain is started as described later). Here, with respect to all the specimens, after demolding 24 hours after placing and then curing in water for 24 hours, that is, 48 hours after placing, the base length (L ₀ ) was measured, and the shrinkage strain (ε) of Measurement started. The shrinkage strain (ε) was calculated by the following formula based on the measured value obtained using a contact strain gauge in accordance with JIS A 1129-2 (where X ₀₁ is the standard scale at the reference time point, X ₀₂ Is the measured value of the specimen at the reference time, X _i1 is the standard scale at time i, and X _i2 is the measured value of the specimen at time i).

From the graph of FIG. 4, the length change rate (shrinkage strain) decreases as the substitution rate increases, and an expansion strain of approximately 100 × 10 ⁻⁶ has developed in the third example (substitution rate 50%). I understand. Further, according to the third example (replacement rate 50%), it can be seen that the shrinkage strain is reduced by approximately 250 × 10 ⁻⁶ after the material age is approximately 30 days, compared with the comparative example (replacement rate 0%). .

  FIG. 5 is a bar graph showing the strength of the mortar specimens according to the comparative example and each example, where (a) shows the bending strength and (b) shows the compressive strength. 5 (a) and 5 (b), all the examples according to the present invention (replacement rate 10, 30, 50%) are all equal to or higher than the comparative example (replacement rate 0%) and the bending strength and compressive strength. It can be seen that both the bending strength and the compressive strength increase as the substitution rate increases.

  The present inventors considered the effects of the present invention proved by the above experimental results as follows.

  First, unlike the present invention, when steelmaking slag is used as an aggregate as it is without being crushed, as shown in FIG. 6 (a), it is made of steelmaking slag inside a hydrated hardened body 100 such as mortar or concrete. The aggregate 111 having a relatively large particle diameter is in a discrete arrangement. Here, when the aggregate 111 expands due to the reaction between the free lime contained in the aggregate 111 and water, the particle size of the aggregate 111 is large, so that cracks 150 are generated in the hydrated cured body 100, thereby Problems such as a decrease in strength are likely to occur in the Japanese cured body 100.

  On the other hand, according to the fine aggregate which concerns on this invention, it is set as a small particle size of about 5 mm or less by passing through a crushing process (S2) and a particle size adjustment process (S3), as shown in FIG.6 (b). In addition, when applied to the hydrated cured body 1 such as mortar or concrete, the fine aggregate 11 is dispersedly arranged inside the hydrated cured body 1. Here, even if the fine aggregate 11 expands due to the reaction between the free lime contained in the fine aggregate 11 and water, the particle size of the fine aggregate 11 is small. It is considered that the crack 150 as shown in FIG.

  On the contrary, when the fine aggregates 11 having relatively small particle diameters dispersed and arranged in the hydrated cured body 1 each undergo volume expansion, drying shrinkage of the hydrated cured body 1 is suppressed, as shown in FIG. It is inferred that the experimental results were obtained.

  Furthermore, according to the fine aggregate according to the present invention, fine particles of steelmaking slag (particles having a particle size smaller than 5 mm) are generated in the crushing step (S2), and the filling effect by these fine particles is exhibited. That is, in the experiment, the fine particles fill the gaps between the fine aggregates 11 in the hydrated cured body 1, thereby reducing the bleeding rate (see FIG. 3), improving the surface quality (not shown), and the strength. It is presumed that the effect of improving (bending strength and compressive strength) (see FIG. 5) was obtained.

  In particular, it is surmised that the free lime contained in the steelmaking slag is finely divided in the crushing step (S2), and the fine pulverized free lime exhibits the above filling effect.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims.

  In the present invention, the hydrated cured product means a product formed by mixing fine aggregate, water, and cement and curing by a hydration reaction, and includes concrete and the like in addition to mortar. That is, the fine aggregate according to the present invention can be applied to concrete as well as mortar as in the above embodiment and examples.

1 Hydrated hardened body 11 Fine aggregate

Claims (2)

The fine aggregate and the fine aggregate consisting of steel slag with a separate fine aggregate, water and cement and curing step of curing by mixing to hydration reaction, a method of producing a hydrated cured body There,
As a manufacturing method of fine aggregate made of the steelmaking slag,
Steelmaking slag produced by the steelmaking process, including aging treatment, air crushing treatment, chemical reaction promotion treatment by addition of additives, and carbonation treatment, free for removing free lime remaining in the steelmaking slag A crushing step of crushing steelmaking slag that has not been subjected to lime removal treatment;
A particle size adjusting step of adjusting the particle size for fine aggregate so that the steelmaking slag crushed in the crushing step passes through a 10 mm sieve and the particle size of 5 mm or less is 85% or more by weight ,
In the hardening step, the fine aggregate made of the steelmaking slag whose particle size is adjusted in the particle size adjusting step is dispersed and arranged in the hydrated hardened body in a state of volume expansion, respectively. . In the crushing step, the free lime contained in the steelmaking slag is finely divided,
2. The method for producing a hydrated cured product according to claim 1, wherein in the particle size adjusting step, the particle size is adjusted so that the free lime finely divided in the crushing step is included as a fine aggregate.

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