JP6593277B2 - Method for judging water-swelling expansion of steel slag and method for producing slag roadbed material - Google Patents

Description

  The present invention relates to a method for determining the water-swellability of steelmaking slag for determining the steel-making slag water-swellability and a method for producing a slag roadbed material using the method for judging the water-swellability of steelmaking slag.

  Steelmaking slag is dense and hard, and can be used as roadbed material because it can support large loads when compacted. However, in the steelmaking slag, a part of calcium oxide (CaO) used at the time of refining remains unreacted, and this CaO undergoes a hydration reaction with moisture such as rainwater and seawater, and expands in volume. For this reason, when using steelmaking slag as a roadbed material (JIS A 5015 crusher run steel slag), it is necessary to perform an appropriate aging process and to suppress volume expansion. Insufficient aging may cause saddle-like irregularities as the roadbed expands over several years, or pops out locally to swell and break through the asphalt, resulting in traffic of vehicles and pedestrians. Inhibits.

  JIS A 5015, which prescribes steel slag for roads, shows the minimum aging period and the upper limit of expansion as a roadbed material for each product type. Many of the steelmaking slag roadbed material products are HMS-25, MS-25, CS-40, etc., and the expansibility is supposed to be 1.5% or less in terms of water immersion expansion. However, sometimes due to variations within the product, the measurement sample meets the standard, but may cause swelling on the road surface several years after installation. For this reason, it is common practice to combine a low-expansion material with steelmaking slag to suppress variations in product expansibility, or to reduce the expansion rate considerably from the standard to achieve safety.

  As a method for determining the expandability of steelmaking slag, for example, in Patent Document 1, the slag is solidified in a container to form a molded body, and then dried in a dryer for a predetermined time, and determined by the presence or absence of cracks on the surface of the molded body. A method is disclosed. In addition to this, there is also a method for judging by the amount hydrated in the high pressure steam of the autoclave and powdered from the beginning.

JP 57-171612 A

  According to roadbed design standards, road durability is expected to be 10 years. However, there are actual situations where durability of about 20 years is required to reduce maintenance costs. That is, the roadbed material is required to have high durability and particularly high stability in terms of steelmaking slag roadbed material. However, even in JIS A 5015, the current expansibility determination does not guarantee that the roadbed will not be collapsed due to the expansion of the steelmaking slag for many years. Other judgment methods do not predict that the roadbed will not collapse due to the expansion of the steelmaking slag over a long period of years under actual use conditions. On the other hand, it is not practical to confirm the expansibility by actually immersing the steelmaking slag for a long time because it takes decades to confirm. Thus, there is no method that can logically guarantee the expansibility of the steelmaking slag roadbed material over a long period of time, and therefore there is no steelmaking slag roadbed material that guarantees the quality for expansive properties for a long time.

  The present invention has been made in view of such a current situation, and an object of the present invention is to provide a method for determining the water immersion expansion of a steelmaking slag capable of logically assuring the quality with respect to the water expansion expandability for a long period of time in a short period of time. And it is providing the manufacturing method of the steelmaking slag roadbed material using the said determination method.

The features of the present invention for solving such problems are as follows.
(1) Calculate the rate of increase of the water immersion expansion rate that rises per unit temperature from the water immersion expansion curves of a plurality of steelmaking slags that have been subjected to water immersion expansion at different temperatures between 40 ° C. and 120 ° C.,
The predetermined temperature at the measurement temperature using the temperature difference between the measurement temperature higher than the predetermined temperature and the increase factor with respect to the water immersion expansion reference value of the steelmaking slag that has been subjected to water immersion expansion for a predetermined time at a predetermined temperature. Calculate the conversion time corresponding to the time,
The water immersion expansion property of the steelmaking slag characterized by determining pass / fail with respect to the water immersion expansion reference value of the steelmaking slag using the water immersion expansion value of the steelmaking slag that has been subjected to the water immersion expansion for the conversion time at the measurement temperature. Judgment method.
(2) Water immersion expansion standard value of steelmaking slag that is water immersion expanded for a predetermined time at a predetermined temperature on a graph with the water immersion time on a logarithmic scale on the horizontal axis and the logarithmic scale on the vertical axis. Take a point indicating
When it is estimated that the water immersion expansion curve of the steelmaking slag measured at the predetermined temperature exceeds a straight line with a gradient extending from the point in a direction in which the water immersion time is shortened to 0.5, the water immersion expansion It is determined that the steelmaking slag is rejected with respect to the reference value, and when it is estimated that the water expansion curve of the steelmaking slag does not exceed the straight line, the steelmaking is determined to be acceptable with respect to the water immersion expansion reference value. A method for judging the water swellability of slag.
(3) The increase rate of the water immersion expansion rate that rises per unit temperature is calculated from the water immersion expansion curves of a plurality of steelmaking slags expanded at different temperatures between 40 ° C. and 120 ° C., and at a predetermined temperature for a predetermined time. Conversion corresponding to the predetermined time at the measurement temperature using the temperature difference between the measurement temperature higher than the predetermined temperature and the increase factor with respect to the water immersion expansion reference value of the steelmaking slag that has been subjected to water immersion expansion Calculate the time, and the horizontal axis represents the water immersion time on a logarithmic scale, and the vertical axis represents the water immersion expansion rate on a logarithmic scale. When the water immersion expansion curve of the steelmaking slag measured at the measurement temperature is estimated to exceed the straight line extending in the direction in which the water immersion time is shortened from the point is 0.5 In addition, with respect to the water expansion reference value It is determined that the steelmaking slag is acceptable, and when it is estimated that the water expansion curve of the steelmaking slag does not exceed the straight line, it is determined that the steelmaking slag is acceptable with respect to the water immersion expansion reference value. Judgment method.
(4) When the water immersion expansion test of JIS A 5015 Annex B is continuously immersed in the measurement temperature, the corresponding time for the same expansion rate is calculated as a statistical average value. Instead of the expansion curve, a straight line extrapolated in a direction in which the water immersion time becomes longer with the gradient of the water immersion expansion curve when the corresponding time elapses in the water immersion expansion curve that has been subjected to water immersion expansion at the measurement temperature is used. (3) The method for determining the water-swellable expansion property of steelmaking slag according to (3)
(5) The water immersion expansion property of the steelmaking slag is determined using the method for determining the water immersion expansion property of the steelmaking slag according to any one of (1) to (4), The manufacturing method of the slag roadbed material characterized by manufacturing a slag roadbed material using the steelmaking slag determined to be acceptable.

  By implementing the method for determining the water immersion expansion of steelmaking slag according to the present invention, the quality with respect to long-term water immersion expansion can be logically guaranteed in a short period of time. Moreover, the slag roadbed material manufactured by the manufacturing method of the steelmaking slag roadbed material using the said determination method can be made into the slag roadbed material in which the quality with respect to the long-term expansibility was logically guaranteed.

It is a graph which shows the result of having performed the water immersion expansion test of decarburization slag on each temperature condition. It is the graph which showed that the water immersion expansion curve of 80 degreeC, 60 degreeC, and 40 degreeC overlapped with the water immersion expansion curve of 100 degreeC. It is a graph explaining that a water immersion expansion curve can be estimated similarly also in various decarburization slag. It is a graph explaining the water immersion expansion determination method of the steelmaking slag which concerns on 1st Embodiment. The graph which converted the water immersion expansion curve of decarburization slag into the logarithmic axis for both the horizontal axis and the vertical axis is shown. It is a graph explaining the water immersion expansion determination method of the steelmaking slag based on 2nd Embodiment applied to the water immersion expansion from which water immersion temperature differs. It is a graph explaining the method of applying the JIS water immersion expansion method to the water immersion expansion determination method of the steelmaking slag which concerns on 2nd Embodiment. It is a graph which shows the result of having determined the water immersion expansion property of decarburization slags AC using the water immersion expansion determination method of steelmaking slag concerning a 2nd embodiment. It is a graph which shows the result of having applied the JIS expansion test result to the water immersion expansion determination method of the steelmaking slag which concerns on 2nd Embodiment.

  Hereinafter, the present invention will be described through embodiments of the invention. FIG. 1 is a graph showing the results of a water immersion expansion test of decarburized slag under each temperature condition. In the graph shown in FIG. 1, the horizontal axis represents the water immersion time (days), and the vertical axis represents the expansion rate (%).

  First, the water immersion expansion test that led to the present invention will be described. Water immersion expansion by changing the temperature conditions of the specimen filled with the same amount of decarburized slag as the sample in the water immersion expansion test (hereinafter referred to as “JIS water immersion expansion method”) specified in JIS A 5015 Annex B The test was conducted. In the JIS water immersion expansion method, a cycle of holding at 80 ° C. for 6 hours per day is repeated for 10 days. In the water immersion expansion test shown in FIG. 1, the water immersion temperature is 100 ° C., 80 ° C., 60 ° C. , 40 ° C., and a water immersion expansion test was carried out while maintaining the temperature. The number of specimens at one temperature is three in combination with the JIS water immersion expansion method, and the average curve of three water immersion expansion curves obtained from the measurement of these three specimens is shown in FIG. . In addition, although the following embodiment demonstrates by the example which used the decarburization slag as a sample, even if it is a desiliconization slag, a dephosphorization slag, an ingot slag etc., if this is a steelmaking slag, this embodiment By applying the method for determining the water-swellability of steelmaking slag according to the above, the water-swellability of the slag can be determined.

  As shown in FIG. 1, when the water immersion temperature is high, the water expansion of the decarburized slag proceeds quickly, and when the water immersion temperature is low, the expansion of the decarburized slag proceeds slowly. The present inventors pay attention to the fact that the expansion rate of the decarburized slag increases regularly as the water immersion temperature increases, and the water immersion expansion rate of the decarburized slag increases as the unit temperature increases. It has been found that the expansion curve at a constant magnification and a temperature lower than 100 ° C. is superimposed on the 100 ° C. expansion curve by shortening the water immersion time axis by the reciprocal of the constant magnification.

  FIG. 2 is a graph showing that the water immersion expansion curves at 80 ° C., 60 ° C., and 40 ° C. overlap the water immersion expansion curves at 100 ° C. In the graph shown in FIG. 2, the horizontal axis represents the water immersion time (days), and the vertical axis represents the expansion rate (%). The expansion curve at 80 ° C overlaps with the 100 ° C water immersion expansion curve by shortening the water immersion time axis to ¼, and the expansion curve at 60 ° C shortens the water immersion time axis to 1/16. It can be overlaid with a 100 ° C. water immersion expansion curve. Furthermore, the 40 ° C. water immersion expansion curve can be overlapped with the 100 ° C. expansion curve by shortening the water immersion time axis to 1/64.

Thus, for example, when an 80 ° C. water immersion expansion curve is to be superimposed on a 100 ° C. water immersion expansion curve, a time axis increases every 10 ° C. with respect to a temperature difference of 20 ° C. between 80 ° C. and 100 ° C. It can be seen that ½ should be reduced. That is, when the 80 ° C. expansion curve is superimposed on the 100 ° C. expansion curve, (1/2) ² = 1/4, and the water immersion time axis of the 80 ° C. water immersion expansion curve may be ¼.

In addition, when the 60 ° C. water immersion expansion curve is superimposed on the 100 ° C. water immersion expansion curve, it rises by 40 ° C. until it reaches 100 ° C., so (1/2) ⁴ = 1/16, and the 60 ° C. water immersion expansion It can be seen that the water immersion time axis of the curve should be 1/16. Similarly, when the 40 ° C. water immersion expansion curve is superimposed on the 100 ° C. water immersion expansion curve, the temperature rises by 60 ° C. until it reaches 100 ° C., so (1/2) ⁶ = 1/64, and 40 ° C. water immersion It can be seen that the water immersion time axis of the expansion curve should be 1/64. Similarly, if the water immersion time axis of the 100 ° C. water immersion expansion curve is quadrupled, it can be superimposed on the 80 ° C. water immersion expansion curve.

  In this way, by calculating the increase rate of the water expansion rate that rises per unit temperature from a plurality of water immersion expansion curves that have been subjected to water expansion at different temperatures, A curve can be estimated. In addition, when the expansion curve of 60 ° C is overlapped with the expansion curve of 80 ° C, not only 100 ° C, the temperature difference is 20 ° C, so the time axis may be shortened to 1/4, and the expansion of 40 ° C When the curve is superimposed on the 80 ° C. expansion curve, the temperature difference is 40 ° C., so the time axis may be shortened to 1/16.

  FIG. 3 is a graph for explaining that the water immersion expansion curve can be similarly estimated in various decarburized slags. FIG. 3A shows a water immersion expansion curve of 40 ° C., 80 ° C., and 100 ° C. of the decarburized slag which is a lot different from the decarburized slag shown in FIGS. Also in the expansion curve of the decarburized slag, as shown in FIG. 3B, assuming that the water immersion expansion speed doubles every time the water immersion temperature increases by 10 ° C., the water expansion expansion curve of 40 ° C. By setting the water immersion time axis to 1/64, it can be superimposed on the 100 ° C. water immersion expansion curve, and by setting the water immersion time axis of the 80 ° C. water immersion expansion curve to 1/4, It was possible to superimpose on the expansion curve.

  Moreover, FIG.3 (c) shows the 40 degreeC, 80 degreeC, and 100 degreeC water immersion expansion curve of the decarburization slag of the steam aging process of another lot. Also in the expansion curve of the decarburization slag, as shown in FIG. 3 (d), assuming that the water immersion expansion speed doubles every time the water immersion temperature increases by 10 ° C, By setting the water immersion time axis to 1/64, it can be superimposed on the 100 ° C. water immersion expansion curve, and by setting the water immersion time axis of the 80 ° C. water immersion expansion curve to 1/4, It was possible to superimpose on the expansion curve.

Moreover, FIG.3 (e) shows the water immersion expansion curve of 40 degreeC, 60 degreeC, 80 degreeC, and 100 degreeC of the decarburization slag of the steam aging process of another lot. In the water immersion expansion curve of the decarburized slag, as shown in FIG. 3 (f), it is assumed that the water immersion expansion rate is 1.9 times for every 10 ° C increase in temperature, and the water immersion expansion at 40 ° C is performed. By setting the water immersion time axis of the curve to 1/47 ((1 / 1.9) ⁶ ), it is possible to overlap the water immersion expansion curve at 100 ° C., and the water immersion time axis of the water immersion expansion curve at 60 ° C. By setting it to 1/13 ((1 / 1.9) ⁴ ), the water immersion expansion curve at 100 ° C. can be superimposed, and the water immersion time axis of the water expansion expansion curve at 80 ° C. is 1 / 3.6 (( By setting it to 1 / 1.9) ² ), it was possible to overlap the 100 ° C. water immersion expansion curve.

  As shown in FIG. 3, even in decarburized slag with different lots and different refining conditions, it was confirmed that the water immersion expansion rate doubled every time the water immersion temperature was increased by 10 ° C. By utilizing such water immersion expansion characteristics of steelmaking slag, the presence or absence of quality for long-term water expansion expansion can be determined in a short period of time. FIG. 4 is a graph for explaining a water immersion expansion determination method for steelmaking slag according to the first embodiment.

  In the water immersion expansion determination method for steelmaking slag according to the first embodiment, first, an increase rate of the water immersion expansion rate that rises per unit temperature of the target steelmaking slag is calculated. The rate of increase in the water expansion rate can vary depending on the material of the steelmaking slag. It is desirable to calculate the increase rate of the expansion rate.

  The increase rate of the water expansion rate can be calculated by measuring a plurality of water expansion curves measured at different temperatures between 40 ° C. and 120 ° C., and comparing the water immersion times to reach a predetermined expansion rate. . In addition, it is preferable to calculate from the three or more water immersion expansion curves from which temperature conditions differ in calculation of the increase rate of a water immersion expansion speed. Moreover, the water immersion conditions may be maintained at 80 ° C. for 6 hours a day and allowed to cool for other times as in the JIS water expansion method. This is not preferable because the error increases. For this reason, it is preferable to continue the water immersion expansion while keeping the water immersion temperature constant.

  Next, after calculating the rate of increase of the water expansion rate that rises per unit temperature, the water expansion rate is actually measured. Here, when the unit temperature is a (° C.), the increase rate of the water immersion expansion rate is b (−). Further, assuming that the water immersion expansion reference value of the steelmaking slag when immersed for a long period of time is set to c (%), the temperature condition and period of the water immersion expansion reference value c are respectively set to a predetermined temperature d (° C.) and The predetermined time is e (day). Further, a measurement temperature higher than the predetermined temperature d is defined as f (° C.), and a conversion time corresponding to the predetermined time e at the measurement temperature f is defined as g (day).

  In practice, the unit temperature a is preferably set to a value at which temperature intervals such as 5 ° C., 10 ° C., and 20 ° C. can be easily separated. Note that it is more preferable that the unit temperature a is 10 ° C., because the calculation is easy. Moreover, when unit temperature is 10 degreeC, the increase rate b of the water immersion expansion speed at the time of using steelmaking slag will be 1.5 or more and 2.5 or less.

  Further, the water immersion expansion reference value c is preferably in the range of 0.5 to 6%, and more preferably in the range of 3 to 5%. The water immersion expansion reference value c is within the above range, and may be 4.0%, for example. This value is the result of the 2012 Civil Engineering Research Report “Study on Physical and Chemical Properties of Pavement Aggregate”. If the expansion of the model roadbed exceeds 4%, the cracks due to the road surface expansion and the roadbed It is a value based on a report that a decrease in support force is seen. The predetermined temperature may be 20 ° C. assuming normal temperature, for example. Furthermore, the predetermined period e is preferably within a range of 10 to 30 years, considering the durability required for roads, for example, 20 years.

  Next, using the water immersion expansion curve measured at the measurement temperature f, it is determined whether or not it is acceptable for the water expansion reference value c that has been subjected to water expansion until a predetermined time e has elapsed at the predetermined temperature d. First, the conversion time g is calculated using the following equation (1).

g = e × (1 / b) ^{(f−d) / a} (1)

  The conversion time g calculated by the equation (1) is a time for water immersion expansion of the steelmaking slag immersed in the water until the predetermined time e elapses at the predetermined temperature d at the measurement temperature f. For this reason, the pass / fail of the steelmaking slag with respect to the water immersion expansion reference value c is determined using the water immersion expansion value of the steelmaking slag after being subjected to water immersion expansion at the measurement temperature f until the conversion time g elapses. Thereby, the pass / fail of the steelmaking slag with respect to the water immersion expansion reference value c can be logically determined in a conversion time g shorter than the predetermined time e.

  Moreover, a slag roadbed material is manufactured using the steelmaking slag which logically guaranteed the long-term water-expandability by the determination method. Thereby, the slag roadbed material in which the quality for the long-term expansibility is logically guaranteed can be manufactured.

  As described above, by first implementing the method for determining the water immersion expansion of steelmaking slag according to the embodiment, the steelmaking slag can be immersed in water for a long period of time without causing the steelmaking slag to be immersed in water for a long period of time. Quality can be logically guaranteed. For example, when the unit temperature a is 10 ° C. and the increase rate b of the water immersion expansion rate is 2 times, when the water immersion expansion reference value c for the predetermined temperature 20 ° C. and the predetermined time 20 years is determined, By performing water immersion expansion at a measurement temperature of 100 ° C., it is possible to determine whether or not the water immersion expansion reference value c is acceptable in about 29 days.

  The measurement temperature is preferably 60 to 120 ° C. from the viewpoint of shortening the water immersion time, and more preferably 80 to 100 ° C. Since 80 degreeC is the same temperature as a JIS water immersion expansion method, since a measuring apparatus is easy to divert, it is more preferable. Further, 100 ° C. is more preferable because it is a condition obtained by steaming under atmospheric pressure and can be measured with a relatively simple apparatus without using a highly airtight container.

  Next, a method for determining water immersion expansion of a steelmaking slag according to the second embodiment will be described. FIG. 5 shows a graph obtained by converting the water immersion expansion curve of decarburized slag into a logarithmic axis for both the horizontal axis and the vertical axis.

  As shown in FIG. 5, when the water immersion expansion curve is converted into a logarithmic axis for both the vertical and horizontal axes, the desorption slag water immersion expansion curve has a gradient close to 1 in the initial stage of water immersion, and then the gradient is Asymptotically approaching 0.5. For example, in an 80 ° C. water immersion expansion curve, the slope becomes 0.5 after 14 days of water immersion. When the water immersion temperature decreases, the position where the gradient asymptotically approaches 0.5 slides in a direction in which the water immersion time increases, and when the water immersion temperature increases, the position where the gradient asymptotically approaches 0.5 shortens the water immersion time. The direction of the gradient asymptotically approached 0.5 was the same.

  In the initial stage of water immersion expansion, the reaction of the expansion source such as free lime and free magnesia is the chemical reaction rate-determined, and the particles collapsed and exposed immediately before the end of vapor aging, and preparation for the water immersion expansion test. This is thought to be due to the reaction of the expansion source on the surface of the cracked particles due to the tamping of the mold at the stage. However, after the reaction on the surface of these particles is finished, the next is that the expansion source inside the particles reacts when moisture enters the cracks that run inside the particles. The reaction inside the particles continues, such as the start of water supply to the expansion source. Since the reaction rate of such a reaction is determined by the rate at which moisture reaches the expansion source inside the particle, the reaction rate becomes diffusion-limited. For this reason, in the graph in which the horizontal axis and the vertical axis are logarithmic axes, it was presumed that all the expansion curves were asymptotic to a straight line having a diffusion-controlling gradient of 0.5.

  Thus, except for the initial stage of water immersion, it is considered that the water immersion expansion is a diffusion-determined reaction in a pseudo manner, which is the overall image of the water immersion expansion reaction of the steelmaking slag. Therefore, it is considered that the water immersion expansion is diffusion-controlled as described above at the time when the water immersion is reached for a long time and reaches the water immersion expansion reference value. Therefore, on the graph with the horizontal axis and the vertical axis as the logarithmic axis, when the water immersion expansion reference value is reached, the water immersion expansion curve of the steelmaking slag is a straight line having a slope of 0.5 and the water immersion expansion reference value. To reach. Therefore, a point indicating the water immersion expansion reference value is taken on a graph with the horizontal axis and the vertical axis as a logarithmic axis, and a straight line having a gradient of 0.5 is extended from the point in a direction in which the water immersion time is shortened. And when it is estimated that the water immersion expansion curve of the steelmaking slag exceeds the straight line having a gradient of 0.5 and does not extend to the high expansion rate side, it can be said that the water immersion expansion reference value is not exceeded, and the gradient is 0. If it is estimated to extend above the straight line of .5 to the high expansion rate side, it can be said that it exceeds the water immersion expansion reference value.

  By utilizing such water immersion expansion characteristics of steelmaking slag, the presence or absence of quality for long-term water expansion expansion can be determined in a short period of time. Specifically, the horizontal axis represents the water immersion time on a logarithmic scale, and the vertical axis represents the water immersion expansion rate on a logarithmic scale. When it is estimated that the water-swelling expansion curve of the steel-making slag measured in step 1 exceeds the straight line in which the slope extending from the point in the direction in which the water-immersion time is shortened is 0.5, If it is determined that the steel expansion slag does not exceed the straight line, it is determined that the steelmaking slag is acceptable with respect to the water immersion expansion reference value.

  On the graph in which the horizontal axis represents the water immersion time on a logarithmic scale and the vertical axis represents the water immersion expansion rate on a logarithmic scale, the water immersion expansion curve gradually approaches a straight line having a slope of 0.5. For this reason, when the water immersion expansion curve is measured and the gradient becomes 0.5, the gradient extending in the direction in which the water immersion time is shortened from the point where the water immersion expansion curve shows the water immersion expansion reference value is 0. It can be estimated whether it exceeds the straight line of .5. As described above, by performing the water immersion expansion determination method for steelmaking slag according to the second embodiment, it is possible to logically guarantee the quality with respect to the long-term water expansion expansion in a short time.

  Further, as defined in the method for determining the water immersion expansion of steelmaking slag according to the first embodiment, the increase rate of the water expansion rate when the unit temperature is a (° C.) is defined as b (−). Further, assuming that the water immersion expansion reference value of the steelmaking slag when immersed for a long period of time is set to c (%), the temperature condition and period of the water immersion expansion reference value c are respectively set to a predetermined temperature d (° C.) and The predetermined time is e (day). Further, a measurement temperature higher than the predetermined temperature d is defined as f (° C.), and a conversion time corresponding to the predetermined time e at the measurement temperature f is defined as g (day). The water immersion expansion reference value c in the method for determining the water immersion expansion of steelmaking slag according to the second embodiment may be determined by a water immersion expansion curve having a predetermined temperature d, but the water immersion expansion speed increased by the unit temperature a. By utilizing the regularity that the increase rate of b is b, it can be applied to water immersion expansion with different water immersion temperatures.

  FIG. 6 is a graph for explaining a water immersion expansion determination method for steelmaking slag according to the second embodiment applied to water immersion expansion with different water immersion temperatures. In FIG. 6, the horizontal axis is a logarithmic axis of water immersion time (days), and the vertical axis is a logarithmic axis of expansion rate (%).

  The point in FIG. 6 shows the water immersion expansion reference value c corresponding to the conversion time g. That is, by using the unit temperature a and the increase rate b of the water expansion rate, the predetermined time e at the predetermined temperature d, which is a condition for measuring the water expansion reference value c, is converted into the conversion time g at the measurement temperature f. Further, it was made to correspond to the water immersion expansion at the measurement temperature f which is a temperature different from the predetermined temperature d.

  The method for determining the water immersion expansion of steelmaking slag according to the second embodiment is a gradient extending in a direction in which the water immersion time is shortened from the point where the water immersion expansion curve of the steelmaking slag shows the water immersion expansion reference value c in the conversion time g. When it is estimated that the water immersion expansion curve of the steelmaking slag does not exceed the straight line with respect to the straight line having a value of 0.5, the water immersion expansion of the steelmaking slag is determined to be acceptable. When it is estimated that the curve exceeds the straight line, it is determined that the curve does not pass the water immersion expansion reference value.

  In FIG. 6, the solid line A shows the water immersion expansion curve at the measurement temperature f of the steelmaking slag A, the one-dot chain line B shows the water immersion expansion curve of the steelmaking slag B at the measurement temperature f, and the two-dot chain line C shows the measurement. The water immersion expansion curve of the steelmaking slag C in the temperature f is shown. The broken line connected to the alternate long and short dash line B is a water immersion expansion curve predicted from the alternate long and short dash line B.

  Since the water immersion expansion curve of the steelmaking slag A does not exceed the straight line having a gradient of 0.5 extending in the direction of shortening the water immersion time from the point indicating the water immersion expansion reference value c, It is determined that the expansion reference value c is acceptable. On the other hand, since the water immersion expansion curve of the steelmaking slag B is estimated to exceed the straight line having a gradient extending in the direction of shortening the water immersion time from the point indicating the water immersion expansion reference value c, the steelmaking slag B is determined to be unacceptable with respect to the water immersion expansion reference value c. Similarly, the water-swelling expansion curve of the steelmaking slag C exceeds the straight line whose slope extending in the direction of shortening the water-immersion time from the point indicating the water-swelling expansion reference value c is 0.5. It is determined that the reference value “c” is not acceptable.

  Here, by making the measurement temperature f higher than the predetermined temperature d, the determination can be made based on the water expansion reference value for the conversion time g shorter than the predetermined time e. It can be determined in a shorter time than the case of determining by. In this way, by applying the method for determining the water immersion expansion of the steelmaking slag according to the second embodiment to the measurement temperature f higher than the predetermined temperature d, the quality for the water expansion expansion property for a long period of time can be further increased. Can be guaranteed.

  Moreover, the measurement result of the JIS water immersion expansion method can be read and applied to the expansion curve continuously immersed in the measurement temperature f. FIG. 7 is a graph for explaining a method of applying the JIS water immersion expansion method to the water immersion expansion determination method for steelmaking slag according to the second embodiment.

  When the JIS water immersion expansion method is applied to the method for determining the water immersion expansion of steelmaking slag according to the second embodiment, first, the measurement by the JIS water immersion expansion method is continued at the measurement temperature f for several hours. It is calculated by a statistical average value whether it corresponds to the case of soaking. Here, the calculated water immersion time is defined as JIS corresponding time i. The straight line extrapolation is performed in the direction in which the water immersion time becomes longer with the slope of the water immersion expansion curve at the time of the JIS corresponding time i in the water immersion expansion curve measured at the measurement temperature f.

  When it is estimated that the straight line extrapolated to the long time side does not exceed the straight line whose slope extending in the direction of shortening the water immersion time from the point indicating the water immersion expansion reference value c is 0.5, If it is determined that the reference value is acceptable and the straight line is estimated to exceed a straight line having a gradient extending to the short time side from the point indicating the water immersion expansion reference value c, the water immersion is 0.5. You may determine with disqualification with respect to an expansion | swelling reference value.

  Further, the slope of the water immersion expansion curve at the time point of JIS corresponding time i is calculated using, for example, changes in the water expansion coefficient on the 8th and 10th days in the JIS water expansion method. The JIS water immersion expansion method is a test that is intermittently maintained at 80 ° C. for 10 days, but with respect to the JIS response time i of 10 days, the response time of 8 days is set to 0.8i, and 0.8i The slope of the water immersion expansion curve at the time point JIS corresponding time i may be calculated from the two points i.

  In other words, the slope obtained by extrapolating the straight line with the slope calculated from the time point JIS corresponding time i of the water immersion expansion curve extends from the point indicating the water immersion expansion reference value c in the direction in which the water immersion time is shortened is 0. If it does not exceed the straight line 5, it is determined that the water immersion expansion reference value c is acceptable, and the straight line extends from the point indicating the water immersion expansion reference value c in a direction in which the water immersion time is shortened to 0. If it does not exceed the straight line of .5, it may be determined that the water immersion expansion reference value c is acceptable. By determining in this way, the measurement result of the JIS water immersion expansion method can be read and applied to a water immersion expansion curve obtained by continuously water immersion expansion at the measurement temperature f. As described above, by implementing the method for determining the water immersion expansion of the steelmaking slag according to the second embodiment, it is possible to logically guarantee the quality with respect to the long term water immersion expansion property in a short period of time.

  Three types of decarburized slags A to C obtained by steam aging of decarburized slags of different lots at 100 ° C. for 2 days or more were used. In accordance with a JIS water immersion expansion test (JIS A 5015, Annex B), a specimen having an inner diameter of 15 cm was used to adjust the moisture content to an optimum water content ratio, and then tamped to prepare a specimen. In the water immersion expansion test, the temperature is kept constant at 80 ° C. and maintained at 80 ° C. for 6 hours a day according to the method of the JIS water immersion expansion test, otherwise the temperature is raised to 80 ° C. or released from 80 ° C. A test with a cold period was also performed.

  In the three types of decarburized slags A to C, a water immersion expansion test was performed at a plurality of temperatures of 40 to 100 ° C., and the rate of increase of the water permeation expansion rate was calculated. When the temperature was set to 10 ° C., the rate of increase in the water expansion rate was 2.0.

The water immersion expansion reference value c was 4.0%, the predetermined temperature d was 20 ° C., and the predetermined time was 20 years (7300 days in terms of days (ignoring leap years)). Each time the temperature rises by 10 ° C., the time axis is shortened by the reciprocal of the increasing magnification (1 / 2.0). Therefore, when the measurement temperature f is 80 ° C., the time axis is shortened to (1 / 2.0) ⁶ = 1/64, and therefore, 7300 days at 20 ° C. corresponds to 114.0 days at 80 ° C. The point (114.0 days, 4.0%) where the water immersion expansion reference value c is 4.0% and the water immersion time is 114 days is taken on the logarithmic scale graph of immersion time-expansion rate, and the short time side. A straight line with a slope of 0.5 was drawn on the surface. The result is shown in FIG.

  FIG. 8 is a graph showing the results of determining the water immersion expansion of the decarburization slags A to C using the method for determining the water immersion expansion of the steel slag according to the second embodiment. In FIG. 8, a solid line A indicates a water immersion expansion curve of the decarburized slag A at 80 ° C., a one-dot chain line B indicates a water immersion expansion curve of the decarburized slag B at 80 ° C., and a two-dot chain line C indicates The water immersion expansion curve of the decarburization slag C in ° C is shown. As shown in FIG. 8, the dewatering slag B, C has a water immersion expansion curve at 10 days of time, the gradient extending from the point (114.0 days, 4.0%) to the short time side is 0.5. It exceeds the straight line and is judged as rejected. On the other hand, the decarburization slag A is a straight line extending from the 10th day with a gradient of 0.5, and a straight line extending from the point (114.0 days, 4.0%) to the short time side with a gradient of 0.5. Since the expansion rate does not reach 4.0% even at the conversion time of 114.0 days, it is judged as acceptable. In this way, by using the method of water immersion expansion of steelmaking slag according to the second embodiment, the predetermined temperature is 20 ° C., and the pass / fail of the water expansion expansion reference value for a predetermined period of 20 years is determined for about 10 days. The expansion test confirmed that it can be logically determined.

  FIG. 9 is a graph showing a result of applying the JIS expansion test result to the water immersion expansion determination method for steelmaking slag according to the second embodiment. In FIG. 9, a solid line A indicates a water immersion expansion curve of the decarburized slag A at 80 ° C., a one-dot chain line B indicates a water immersion expansion curve of the decarburized slag B at 80 ° C., and a two-dot chain line C indicates The water immersion expansion curve of the decarburization slag C in ° C is shown.

  As a result of continuously performing the water immersion expansion test and the JIS water immersion expansion test at 80 ° C., the expansion rate when the water immersion expansion is continued at 80 ° C. is the same as the expansion rate on the 10th day of the JIS expansion test. The JIS response time i was 4.0 days on average, and the JIS response time 0.8i that was the same as the expansion rate on the 8th day of JIS expansion test was 3.2 days on average. The immersion time when calculating the gradient from the change in expansion rate at 4.0 days is 3.2 days and 4.0 days, and the same gradient as calculated from these two points is used for 4.0 days. Assuming that the water was swollen from the time point, extrapolation was performed from the 4.0 day point to the long time side. In the present embodiment, an example in which the JIS response time i was 4.0 days on average was shown, but the JIS response time i may vary depending on the heater capacity of the water tank used in the JIS water immersion expansion method. . That is, when the rate of temperature increase up to 80 ° C. of the water tank heater is high and / or when the temperature of the water tank is high and the cooling rate from 80 ° C. is low, the JIS response time i is 4.0 days. When the temperature rise rate of the water tank heater to 80 ° C. is slow and / or the heat retention rate of the water tank is low and the cooling rate from 80 ° C. is high, the JIS response time i is 4 It will be shorter than 0 days.

  Since the decarburization slags B and C exceed the straight line with the gradient 0.5 extending from the point (114.0 days, 4.0%) to the short time side, the determination is rejected. The decarburized slag A does not exceed the straight line with a slope of 0.5 extending from the point (114.0 days, 4.0%) for a short time, and the expansion rate is 4.0% even at the conversion time of 114.0 days. Since it does not reach, it becomes a pass judgment. As described above, by using the water immersion expansion method for steelmaking slag according to the second embodiment, whether the predetermined temperature is 20 ° C. or not with respect to the water immersion expansion reference value for a predetermined period of 20 years is used as a result of the JIS expansion test result. It was confirmed that it can be judged.

Claims (4)

Point where the horizontal axis represents the water immersion time on a logarithmic scale, and the vertical axis represents the water expansion rate on a logarithmic scale. Take
When the water immersion expansion curve of the steelmaking slag measured at the predetermined temperature is estimated to exceed a straight line with a gradient extending from the point in a direction in which the water immersion time is shortened to 0.5, the water immersion expansion It is determined that the steelmaking slag is rejected with respect to the reference value, and when it is estimated that the water expansion curve of the steelmaking slag does not exceed the straight line, the steelmaking is determined to be acceptable with respect to the water immersion expansion reference value. A method for judging the water swellability of slag. From the water immersion expansion curves of a plurality of steelmaking slags expanded at different temperatures between 40 ° C. and 120 ° C., the increase rate of the water immersion expansion rate rising per unit temperature is calculated,
The predetermined temperature at the measurement temperature using the temperature difference between the measurement temperature higher than the predetermined temperature and the increase factor with respect to the water immersion expansion reference value of the steelmaking slag that has been subjected to water immersion expansion for a predetermined time at a predetermined temperature. Calculate the conversion time corresponding to the time,
On the graph with waterlogging time on the logarithmic scale on the horizontal axis and the waterlogging expansion rate on the logarithmic scale on the vertical axis, a point indicating the water immersion expansion reference value of the steelmaking slag corresponding to the conversion time is taken. ,
When the water immersion expansion curve of the steelmaking slag measured at the measurement temperature is estimated to exceed a straight line having a gradient extending from the point in a direction in which the water immersion time is shortened to 0.5, the water immersion expansion It is determined that the steelmaking slag is rejected with respect to the reference value, and when it is estimated that the water expansion curve of the steelmaking slag does not exceed the straight line, the steelmaking is determined to be acceptable with respect to the water immersion expansion reference value. A method for judging the water swellability of slag. When the measurement of the water immersion expansion test of JIS A 5015 Annex B is continuously immersed in the measurement temperature, the corresponding time for the same expansion rate is calculated as a statistical average value,
Instead of the water immersion expansion curve, linear extrapolation was performed in the direction in which the water immersion time was increased while maintaining the slope of the water immersion expansion curve when the corresponding time elapsed in the water immersion expansion curve that was water-expanded at the measurement temperature. The method for determining the water-swelling expansibility of steelmaking slag according to claim 2 , wherein a straight line is used. The water-swelling expansibility of steelmaking slag is determined using the method for judging the water-swelling extensibility of steelmaking slag according to any one of claims 1 to 3 ,
A method for producing a slag roadbed material, comprising producing a slag roadbed material using steelmaking slag determined to be acceptable with respect to the water immersion expansion reference value.

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