JP6015958B2 - Quality control method of solidified body - Google Patents

Description

  The present invention relates to a method for managing the elution property of an alkali component when shipping a solidified body or concrete using steelmaking slag or starting use in a sea area or a water area.

  In the steel manufacturing process, a large amount of steel slag is generated as a by-product. These steel slags include blast furnace slag generated from a blast furnace and steelmaking slag generated from a converter and an electric furnace, and have been reused as aggregates, roadbed materials, cement raw materials, and the like.

  By the way, among the above steel slag, steelmaking slag contains free CaO and MgO, and these oxides have the property of expanding when they react with water. The application to solidified bodies such as concrete can cause cracks due to expansion. Concern was an obstacle to promote reuse. However, this problem is almost eliminated with the establishment of stability evaluation methods and quality standards for preventing expansion cracking (see Patent Documents 1 to 4), and blast furnace slag and cement are hardened (binding material). ) And steel slag hydrated solidified body using steelmaking slag as an aggregate, enabling the same mixing design and handling as concrete, and the technical manual shown in Non-Patent Document 1 is disclosed. Yes. As a result, steelmaking slag has come to be used as a substitute for concrete products such as wave-dissipating blocks, curb blocks for roads, and covering blocks, and natural stones such as artificial stones.

  However, as mentioned above, steelmaking slag contains a large amount of CaO and MgO alkali components, and the cement cement and blast furnace slag fine powder also contain alkali components such as CaO. The solidified body such as concrete solidified by the water is alkaline when contacted with water, so the range of use is limited, and it cannot be shipped or used immediately after the solidified body is manufactured. There was a problem. In addition, it is qualitatively understood that the pH value when the solidified body is immersed in seawater or water varies depending on the blending ratio of the raw materials of the solidified body from Non-Patent Document 1, Non-Patent Document 2, and the like. .

Japanese Patent Laid-Open No. 2004-301531 JP 2004-301686A JP 2004-301694 A JP 2004-301747 A

"Technical Manual for Steel Slag Hydrated Solids-Effective Utilization Technology for Steel Slag-(Revised Version)"; Coastal Technology Research Center, February 2008 Sekihiro et al., “Experimental Study on Aque of Concrete Dipped in Seawater”; 14, no. 4 (1975), p. 112-132

  However, in Non-Patent Documents 1 and 2, the pH value of the elution water changes completely depending on the blending ratio of the raw materials of the solidified body and the elapsed time (curing time) after the solidified body is formed. Not disclosed. Therefore, when shipping a solidified body such as concrete or starting to use it, the elution property of the alkali component of the solidified body is examined in advance, and in the case of failure, for example, the solidified body is washed with seawater. After taking measures such as reducing the elution of alkali components, it was used for shipment and use. Therefore, the solidified body and concrete using steel slag have a problem that the load at the time of shipment or start of use is large.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to solidify the solidified body using steelmaking slag and the solidified body capable of accurately predicting the elution properties of alkali components from concrete. Is to propose a quality control method.

  In order to solve the above-mentioned problems, the inventors considered the influence of the mixing ratio of solidified material and concrete raw materials using steelmaking slag and the elapsed time (curing time) after solidification on the dissolution properties of alkali components. Numerous experiments were conducted and investigated. As a result, the elution property of the alkali component is determined by the type and mixing ratio of the binder in the raw material of the solidified body and the water content in the solidified body at the time of manufacture (the unit water amount in the indicated composition and the water that the aggregate can saturate). The present invention has been developed by finding that the elution of an alkali component can be accurately predicted by correlating them.

That is, the present invention is steel slag, Portland cement, the elution of alkali component of the solidified body of the blast-furnace slag cement and ground granulated blast furnace slag or al least one raw material selected cured by hydration reaction, the following equation;
A value = W / (PC + 0.9 × BC + 0.7 × BP + CH + 1.36 × C + SS ^* )
Here, W: total value of unit water volume and water absorbed by the aggregate (kg / m ³ )
PC: Unit Portland cement amount (kg / m ³ )
BC: Unit blast furnace cement amount (kg / m ³ )
BP: Unit blast furnace slag fine powder amount (kg / m ³ )
CH: Unit slaked lime amount (kg / m ³ )
C: Amount of unit lime (kg / m ³ )
SS ^* : Unit steelmaking slag amount of 0.15 mm or less (kg / m ³ )
This is a quality control method for a solidified body, characterized in that evaluation is performed using an A value represented by
The quality control method of the said solidified body of this invention is characterized by adding slaked lime or / and lime to the raw material of the said solidified body.

  The quality control method of the solidified product according to the present invention is characterized in that the curing time in air from the production of the solidified product to shipment or the start of use is managed based on the value A.

  According to the present invention, since it is possible to accurately perform the quantitative prediction of the elution property of the alkali component from the solidified body and concrete using the steelmaking slag, the atmosphere required from the design stage for determining the raw material composition of the solidified body The medium curing time can be grasped, and stable shipment and service are possible.

Formulation No. in Table 1 It is a graph which shows the influence of the curing time which acts on the pH maximum value when 1-4 solidified bodies are immersed in artificial seawater. It is a graph which shows the influence of A value and the curing time in air | atmosphere on the pH maximum value when the solidified body shown in Table 1 is immersed in artificial seawater.

First, the experiment and study results that led to the development of the present invention will be described.
Portland cement, blast furnace cement, ground granulated blast furnace slag, slaked lime, lime and fly ash are kneaded in the blending ratio shown in Table 1, and poured into a mold (diameter: 100 mmφ × height: 220 mm) (volume: 1.57 L). After the time, the formwork was removed. Thereafter, the film was cured in a room atmosphere maintained at 20 ° C. for a predetermined time, specifically, 7 days, 28 days, and 91 days after removing the formwork. Next, the solidified body cured for a predetermined time is immersed in artificial seawater having a volume 15 times the volume of the solidified body, and the pH change of the artificial seawater is measured over 2 weeks. The maximum value pH _max was investigated.

The measurement results of the maximum pH pH _max are shown in Table 1. Further, FIG. 1 shows the relationship between the pH _{max of} Formulations 1 to 4 shown in Table 1 above and the curing time in the air. For reference, the measurement results of pH _max of solidified bodies immersed in artificial seawater for 28 days are also shown in the figure. In addition, the pH value of the artificial seawater reached a maximum around 7 days after being immersed in the artificial seawater, and thereafter a tendency to decrease was observed.

From Table 1 and FIG. 1, the pH _max varies depending on the blending ratio of the raw material of the solidified body, but the pH _max value becomes artificial as the curing time in the atmosphere becomes longer at any blending ratio. Approaching the initial pH value of seawater (8.2), but when immersed in artificial seawater for 28 days, each formulation shows a higher pH _max than when cured in air for 7 days I understand that. This is because, when the solidified body is cured in the air, the alkaline component (mainly CaO component) exposed on the surface of the solidified body reacts with carbon dioxide in the air and is carbonated, so that elution is suppressed. On the other hand, it is considered that the above reaction is hardly expected in artificial seawater (underwater). The pH of the seawater is estimated to be determined by the balance between the elution rate of alkali components from the solidified body and the neutralization rate of seawater due to the dissolution of carbon dioxide in the atmosphere, and the value of pH _max is 7 days after immersion. The reason for appearing before and after the eyes is considered to be that the neutralization rate of seawater exceeds the elution rate of the alkaline component from the solidified body after this.

Here, the items (W ₀ , PC, BC, BP, CH, C, FA, SS, S, G) of the blending ratio shown in Table 1 will be described.
W _{0: W 0} is the unit water amount (kg ^{/ m} 3) needed to make a solidified body of 1 m ^3, that is, that the unit quantity of water indicated in How to Display formulation when solidified body produced. However, _{W 0} is the aggregate is a value when (SS in Table 1 (0.15-5mm), SS (5-20mm ), S, G) to the surface dry water-saturated state, while the aggregate The amount of water included is not included.
PC: PC is a unit Portland cement amount (kg / m ³ ), and the above Portland cement means “Portland cement” defined in JIS R5210.
BC: BC is a unit blast furnace cement amount (kg / m ³ ), and the above blast furnace cement means “blast furnace cement” defined in JIS R5211.
BP: BP is a unit blast furnace slag fine powder amount (kg / m ³ ), and the above blast furnace slag fine powder means “blast furnace slag fine powder for concrete” defined in JIS A6206.
CH: CH is the amount of unit slaked lime (kg / m ³ ), and the slaked lime is “special name” (Ca (OH) ₂ of slaked lime in “industrial lime” defined in JIS R9001. Density> 72.5%), but not limited to this.
C: C is the amount of unit lime (kg / m ³ ), and the above lime means “special name” (CaO concentration ≧ 93%) of quick lime in JIS R9001 “industrial lime”. This means but is not limited to this.
FA: FA is fly ash (fine ash generated when coal is fueled).
SS: SS is the unit steelmaking slag amount (kg / m ³ ). In Table 1, SS is a particle size measured by a sieving method and is divided into three parts of 0.15 mm or less, 0.15 to 5 mm, and 5 to 20 mm.
S: S is a unit amount (kg / m ³ ) of natural fine aggregate having a particle size of 5 mm or less measured by a sieving method.
G: G is a unit amount (kg / m ³ ) of natural coarse aggregate having a particle size of 5 to 20 mm measured by a sieving method.

Next, in order to quantify the influence of various factors on the maximum pH value pH _max , the inventors have various factors that are considered to be related to pH in addition to the mixing ratio of the raw materials shown in Table 1, for example, Multiple regression analysis was repeated by taking into account the unit water amount in the blending and the amount of water that could be absorbed into the aggregate. As a result, it was found that there is a very good correlation between the pH _max and the parameter A value represented by the following formula, as shown in FIG.
A value = W / (PC + 0.9 × BC + 0.7 × BP + CH + 1.36 × C + SS ^* )
Here, W: the total value (kg / m ³ ) of the unit amount of water W ₀ and the amount of water W _k absorbed by the aggregate
PC: Unit Portland cement amount (kg / m ³ )
BC: Unit blast furnace cement amount (kg / m ³ )
BP: Unit blast furnace slag fine powder amount (kg / m ³ )
CH: Unit slaked lime amount (kg / m ³ )
C: Amount of unit lime (kg / m ³ )
SS ^* : Unit steelmaking slag amount of 0.15 mm or less (kg / m ³ )

From FIG. 2, even if the blending ratio of the solidified body is changed, the maximum pH pH _max that appears when immersed in artificial seawater has a good correlation with the A value, and in the same curing time in the atmosphere, the A value _{pH max} is that lower the higher, also, in the solidified body having the same a value, a value of about _{pH max} longer curing time in the atmosphere be lower, _thus, reduce the _{pH max,} i.e., alkali In order to suppress the elution of the components, it is understood that the blending ratio should be designed so that the A value of the solidified body becomes high and / or the curing time in the atmosphere should be increased.

For example, when the shipment judgment standard or the service start standard of the solidified body is when the pH _max value is the same as seawater pH = 8.2, the solidified body having an A value of 1.04 or more is 7 in the atmosphere. It can be seen that it is sufficient to cure for 91 days or more in the atmosphere when the A value is 0.96 or more, while it may be cured for more than a day.

Here, the new codes W and SS * in the equation for obtaining the A value will be described.
W: W is the total value (kg / m ³ ) of the unit water amount W ₀ described above and the amount of water W _k contained in the aggregate when the aggregate is in a surface dry saturated state. The _{W k} is that the unit quantity of water contained in the aggregate during in solidified ^{1m 3 (kg / m 3)} , JIS A1109 or "Density and water absorption test method fine aggregate", JIS A1110 " It corresponds to the water absorption rate of the aggregate described in “Density and water absorption test method of coarse aggregate”. In the present invention, in addition to the amount of water contained in the fine aggregate and coarse aggregate, the amount of water contained in the steelmaking slag SS having a size of 0.15 mm or more is also included.
SS ^* : SS ^* is a unit steelmaking slag amount (kg / m ³ ) of 0.15 mm or less. The reason why only the unit mass of steelmaking slag having a size of 0.15 mm or less is used for the calculation of the A value is that the influence of the alkali elution on the solidified body is due to the fine particles having a large surface area of 0.15 mm or less. Because there is. In addition, what is necessary is just to calculate SS as 0 (zero), when not using steelmaking slag as a raw material of a solidification body. Therefore, what does not use steelmaking slag is contained in the solidified body of this invention. As this example, the combination No. 1 using natural aggregate and ordinary Portland cement in Table 1 was used. 1 and No. 1 using natural aggregate and blast furnace cement. 2 is mentioned.

Note that points to be considered when calculating the A value will be described.
BC: There are three types of blast furnace cement: Type A, Type B, and Type C. Since Type B is generally used, the coefficient in the above formula shows the value of Type B. ing. In the case of using Type A or Type C instead of Type B, the ratio of the mixing rate of blast furnace slag fine powder in Type A or Type C to the mixing rate of Type B blast furnace slag fine powder is multiplied by the above coefficient. The value may be used.
CH: When using slaked lime having a calcium hydroxide concentration lower than the “special name” (Ca (OH) ₂ concentration ≧ 72.5%) of “industrial lime” defined in JIS R9001, the coefficient in the formula Need to be corrected. For example, when the calcium hydroxide concentration of the slaked lime used is 60%, “60 / 72.5 = 0.83” may be multiplied by the coefficient of CH in the formula.
C: Similarly, when using quick lime having a calcium oxide concentration lower than the “special name” (CaO concentration ≧ 93%) of JIS R9001 “industrial lime”, the same as in the case of slaked lime described above, What is necessary is just to correct | amend the coefficient of C.
The present invention has been developed based on the above-described novel findings.

Next, the quality control method of the solidified body and concrete of the present invention will be described.
First, the solidified body targeted by the present invention is a solidified body obtained by hardening one or more raw materials selected from steelmaking slag, Portland cement, blast furnace cement, blast furnace slag fine powder, slaked lime and lime by a hydration reaction. However, the solidified body may not use steel slag as a raw material. In addition to the above raw materials, fly ash (FA) may be included, but FA is not involved in the A value.

And the quality control method of the solidified body and concrete of the present invention is based on the following formula based on the blending ratio of the raw materials of the solidified body, the unit water amount shown in the formula blending, and the amount of water that can be saturated in the aggregate. ;
A value = W / (PC + 0.9 × BC + 0.7 × BP + CH + 1.36 × C + SS ^* )
Here, W: total value of unit water volume and water absorbed by the aggregate (kg / m ³ )
PC: Unit Portland cement amount (kg / m ³ )
BC: Unit blast furnace cement amount (kg / m ³ )
BP: Unit blast furnace slag fine powder amount (kg / m ³ )
CH: Unit slaked lime amount (kg / m ³ )
C: Amount of unit lime (kg / m ³ )
SS ^* : Unit steelmaking slag amount of 0.15 mm or less (kg / m ³ )
The A value represented by the formula (1) is obtained, and based on this A value, the curing time in the atmosphere from the production of the solidified body to shipment or the start of use is determined.

Specifically, when the air curing time is managed using the numerical value of the A value, it may be set according to the state of the seawater flow or the like, but even when the seawater flow is small, the above A value is 1 When it is 0.04 or more, the curing time in the atmosphere is 7 days or more, and when the A value is 1.01 or more and less than 1.04, the curing time in the atmosphere is 28 days or more. Is 0.96 or more and less than 1.01, by securing a curing time in the atmosphere of 91 days or more, the pH when immersed in seawater will be slight or not increased. In a place where there is a flow of seawater, the curing time in the atmosphere may be even shorter. For example, when the A value is 0.90 or more, the curing time in the atmosphere is 7 days or more, When the A value is 0.74 or more and less than 0.90, the curing time in the atmosphere is 28 days or more. When the A value is 0.62 or more and less than 0.74, the curing is performed in the atmosphere. If the time is secured for 91 days or more, the cloudiness of seawater does not occur and there is no problem in practical use.

  Here, the curing time in the air means the time when the solidified body or the surface of the concrete is in contact with the air, regardless of whether it is outdoors or indoors, but does not include the time immersed in water. . Moreover, when manufacturing by driving into a formwork such as a block, the time covered with the formwork is not included in the curing time, but is the time after the formwork is removed. Moreover, when crushing a solidified body, although it depends on the degree of crushing, it is set as the time after a new crushing surface appears.

  The 2 ton-type covering block was manufactured by changing the composition of the solidified body and concrete using steelmaking slag in various ways within the range shown in Table 2. Under the present circumstances, the test piece of diameter: 100mmphixheight: 200mm (volume: 1.57L) was produced for every production lot from which an indication mixing | blending and a manufacture date change.

Next, when shipping the 2-ton coated block as a product, several product lots to be shipped are selected, and a test piece of the selected lots is immersed in about 31 L of artificial seawater to measure pH change over time. The test was carried out, and a sample having a maximum pH of pH _max of 8.5 or less was accepted as a pass, a sample exceeding 8.5 was rejected, and an alkali elution test was conducted again in another lot. The reason why the pH passed 8.5 or less is that the block size is large, so the area in contact with the seawater is small relative to the volume. This is because the level does not rise at all.
The product lot to be shipped was selected by the following two methods.
・ Method 1: Select from the oldest manufacturing date (comparative example)
-Method 2: From the formulation of the production lot, the following formula:
A value = W / (PC + 0.9 × BC + 0.7 × BP + CH + 1.36 × C + SS ^* )
Here, W: total value of unit water volume and water absorbed by the aggregate (kg / m ³ )
PC: Unit Portland cement amount (kg / m ³ )
BC: Unit blast furnace cement amount (kg / m ³ )
BP: Unit blast furnace slag fine powder amount (kg / m ³ )
CH: Unit slaked lime amount (kg / m ³ )
C: Amount of unit lime (kg / m ³ )
SS ^* : Unit steelmaking slag amount of 0.15 mm or less (kg / m ³ )
When the A value is 1.04 or more, the curing time is 7 days or more. When the A value is 1.01 or more, the curing time is 28 days or more. When the value is 0.96 or more, select the one having a curing time of 91 days or more (invention example)

  When the incidence rate of rejected lots in the above two selection methods was compared, it was 35% in the method of the comparative example that selects the product lots shipped in the order of manufacture date, but based on the A value In the method of the present invention selected, it was 0%. From this result, it was confirmed that the product shipment of the solidified body can be performed without delay by applying the quality control method of the present invention.

  The technology of the present invention can be applied to concrete produced using natural aggregate, Portland cement and the like in addition to steelmaking slag.

Claims (3)

Evaluation of the elution properties of the alkali components of solidified products obtained by hardening one or more raw materials selected from steelmaking slag, Portland cement, blast furnace cement and blast furnace slag fine powder by hydration reaction using the A value represented by the following formula A quality control method for a solidified body characterized by:
A value = W / (PC + 0.9 × BC + 0.7 × BP + CH + 1.36 × C + SS ^* )
Here, W: total value of unit water volume and water absorbed by the aggregate (kg / m ³ )
PC: Unit Portland cement amount (kg / m ³ )
BC: Unit blast furnace cement amount (kg / m ³ )
BP: Unit blast furnace slag fine powder amount (kg / m ³ )
CH: Unit slaked lime amount (kg / m ³ )
C: Amount of unit lime (kg / m ³ )
SS ^* : Unit steelmaking slag amount of 0.15 mm or less (kg / m ³ ) The quality control method for a solidified body according to claim 1, wherein slaked lime or / and lime are added to the raw material of the solidified body. The quality control method for a solidified body according to claim 1 or 2, characterized in that the curing time in the air from the production of the solidified body to shipment or the start of use is managed based on the A value.

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