KR100367480B1 - Secondary concrete product with high stiffness using blast furnace slag and process for preparation thereof - Google Patents

Abstract

The present invention relates to a high-strength concrete secondary product using the blast furnace slag and a method of manufacturing the same, the blast furnace slag as an industrial waste under the conditions of vibration time 5 ~ 10 seconds, pressing force 6 ~ 12kgf / cm ² of 20 ~ instead of cement Concrete secondary product of the present invention manufactured using 40% replacement has an excellent effect of improving the compressive strength up to 500kgf / cm ² .

Description

Secondary concrete product with high stiffness using blast furnace slag and process for preparation according to blast furnace slag

The present invention relates to a high-strength concrete secondary product using the blast furnace slag and a method of manufacturing the same. More particularly, the present invention relates to a high-strength concrete secondary product manufactured by recycling blast furnace slag which is industrial waste, and a method of manufacturing the same.

As industrial activities are rapidly progressing, various industrial wastes are a major cause of environmental destruction such as pollution generation, and their treatment methods and costs have emerged as social issues.However, recently, local NIMBY phenomenon centered on local governments to properly finalize industrial wastes. As landfills that can be disposed of are being reduced, it is urgent to recycle industrial wastes as a way for proper disposal of industrial wastes.

In Korea, blast furnace slag generation is over 5 million tons per year, and blast furnace slag of 50-600,000 tons is generated annually in Boryeong and Dangjin thermal power plants in Chungcheongnam-do province.

The present inventors selected the production conditions through laboratory research on the method of using them as raw materials substitutes for cement and sand through the grasp of basic properties for proper treatment and recycling of these wastes, and establish the optimum manufacturing conditions in the actual site. Was intended.

Therefore, the present inventors have studied to apply industrial blast furnace slag economically and safely to the secondary concrete products for economical and safe recycling, and when the concrete secondary product is formulated with an appropriate amount of blast furnace slag under the specific conditions, it is compressed. The present invention was completed by confirming that the strength was improved.

An object of the present invention is to provide a high-strength concrete secondary product manufactured by recycling the blast furnace slag of industrial waste.

Another object of the present invention to provide a method for producing the high-strength concrete secondary product.

The above object of the present invention is to examine the compressive strength characteristics of mortar according to the blast furnace slag replacement rate by the cement mortar compressive strength test method of ASTM C 109, and then the secondary construction of high-strength concrete by vibratory compression molding method of construction secondary product production method In manufacturing the product, after manufacturing the concrete secondary products with different vibration time and pressure conditions, the performance of each concrete secondary product manufactured is examined and the appropriate blast furnace slag replacement rate and optimum for producing high strength concrete secondary products This was achieved by determining the vibration time and the pressing force condition.

Hereinafter, the configuration of the present invention will be described.

1 is a graph showing the result of measuring the compressive strength of the mortar in which the blast furnace slag recycled in the present invention in various amounts after 3 days of age.

Figure 2 is a graph showing the results of measuring the compressive strength of the mortar 7 days after the blast furnace slag recycled in the present invention in various amounts.

Figure 3 is a graph showing the results of measuring the compressive strength of the concrete secondary product of the present invention prepared according to the change in the pressing force using only cement.

Figure 4 is a graph showing the result of measuring the compressive strength of the concrete secondary product of the present invention manufactured according to the change in pressure after replacing the blast furnace slag 30% instead of cement.

Figure 5 is a graph showing the results of measuring the compressive strength of the concrete secondary product of the present invention fixed according to the change in the vibration time of the pressing force of the vibration compression molding machine using only cement 8kgf / cm ² .

Figure 6 is a graph showing the results of measuring the compressive strength of the concrete secondary product of the present invention prepared according to the change in the pressing force and the vibration time is fixed to 5 seconds.

Figure 7 is a graph showing the results of measuring the compressive strength of the concrete secondary product of the present invention prepared according to the change in the pressing force and the vibration time is fixed to 10 seconds.

Figure 8 shows the result of comparing the relationship between the density of the conventional concrete secondary product and the concrete secondary product of the present invention and the compressive strength.

9 is a graph showing the results of measuring the compressive strength of the concrete secondary product of the present invention manufactured by replacing various amounts of blast furnace slag after one day of age.

10 is a graph showing the result of measuring the compressive strength of the concrete secondary product of the present invention manufactured by replacing various amounts of blast furnace slag after 3 days of age.

11 is a graph showing the result of measuring the compressive strength of the concrete secondary product of the present invention manufactured by replacing various amounts of blast furnace slag after 7 days of age.

Figure 12 shows the results of comparing the compressive strength of the concrete secondary products of the present invention prepared by replacing various amounts of blast furnace slag according to age.

The present invention is the mortar compressive strength according to the blast furnace slag replacement rate by measuring the compressive strength according to the cement mortar compressive strength test method of ASTM C 109 after replacing the blast furnace slag 0, 20, 30, 40, 50% as a cement substitute in the manufacture of mortar Examining expression characteristics; Investigate the optimal pressing force of the vibratory compression molding machine for the replacement amount of the blast furnace slag in the manufacture of the concrete secondary products by measuring the compressive strength after manufacturing the concrete secondary products by varying the pressing force of the vibratory compression molding machine according to the replacement amount of the blast furnace slag step; Optimal vibration compression in manufacturing concrete secondary products by measuring the compressive strength after manufacturing the concrete secondary products by fixing the pressing force of the vibration compression molding machine to 8kgf / cm ² and varying the vibration time to 5 seconds, 10 seconds and 15 seconds. Examining the vibration time of the molding machine; Optimizing the pressing conditions according to the vibration time of the vibration compression molding machine by measuring the compressive strength after manufacturing the concrete secondary products with various pressing pressures under the vibration time conditions of the optimum vibration compression molding machine when manufacturing the determined concrete secondary products; Comparing the values of the density and compressive strength of the prepared concrete secondary products of the present invention with those of conventional concrete secondary products; and W / B 28% and blast furnace slag replacement rate is 0, 20, 30, 40% After the concrete secondary product is set to 4 levels as described above, the compressive strength is measured at each age and the appropriate blast furnace slag replacement rate for developing the high-strength concrete secondary product is composed.

In the present invention, when the blast furnace slag in place of cement is W / B 28%, 20 to 40% can be used to prepare a secondary concrete product having excellent compressive strength.

In the present invention, when the vibration time of the vibration compression molding machine is 5 to 10 seconds, a secondary concrete product having excellent compressive strength can be manufactured.

In the present invention, when the pressing force of the vibration compression molding machine is 6 to 12 kgf / cm ² , the secondary concrete product having excellent compressive strength can be manufactured.

Hereinafter, the specific method of the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited only to these Examples.

Example 1: Mortar compressive strength expression characteristics according to blast furnace slag replacement rate

The blast furnace slag granulated and quenched from the molten state produced by industrial waste is an irregular meshed glass structure of high lime aluminate silicate and has latent hydraulic properties. In this example, the experiment was carried out according to the experimental plan as shown in Table 1 in accordance with the cement mortar compressive strength test method of ASTM C 109 to examine the blast furnace slag replacement rate and the compressive strength characteristics of the blast furnace slag cement. The blast furnace slag replacement rate was 0, 20, 30, 40, 50% in terms of cement weight replacement rate. The water-binding material ratio (W / B) was 48.5%, and the test body was made of a 5 x 5 x 5 cm molding mold, and cured to each measurement age under the condition of 23 ± 1.7 ° C and 100% humidity. The number of experiments was repeated three times, and the compressive strength was measured at 3 and 7 days of age. Among the materials used in this example, cement was used as the common portland cement of Ssangyong Yangyang, Korea. The blast furnace slag cement and the blast furnace slag were made by Sungshin Yangkai, and the sand was Gongju-san sand. The formulation was based on the water-binder ratio (W / B) 48.5%, which was used in the ASTM C 109 test method, and the blast furnace slag was replaced with 0, 20, 30, 40, and 50% by weight of cement as shown in Table 2. The sand was made constant regardless of the replacement rate of the blast furnace slag. The specimens were made of 5 × 5 × 5cm molding molds and cured to each measurement age under the condition of 23 ± 1.7 ℃ and 100% humidity according to ASTM C 109. Compressive strength was measured by the Portable Compression Meter (10ton) at 3 and 7 days of age.

As a result of the experiment, as shown in Table 3 and Figures 1 and 2, the blast furnace slag replacement rate of 20% and 30% showed the same compressive strength as the blast furnace slag replacement rate of 0% at the blast furnace slag replacement rate of 30%. It was shown to decrease.

On the seventh day, except for the blast furnace slag replacement rate of 50%, the compressive strength of the blast furnace slag replacement rate was 0%.

The standard deviation of the compressive strength measurements showed that the variation in compressive strength at 7 days was greater than at 3 days.

Experiment plan Blast furnace slag replacement rate (%) Experiment method Metric Remarks 0 ASTM C 109 Cement Mortar Compressive Strength Test Method Compressive strength (3 days, 7 days of age) W / B: 48.5% Repetition of experiments: 3 times 20 30 40 50 SC ⁽¹⁾ (1) Blast furnace slag cement (cement: blast furnace slag = 70:30)

Formula Blast furnace slag replacement rate (%) W / B (% / wt) Water (% / wt) Cement (% / wt) Blast furnace slag (% / wt) Sand (% / wt) Total (% / wt) 0 48.5 11.5 23.6 0 64.9 100 20 48.5 11.5 18.9 4.7 64.9 100 30 48.5 11.5 16.5 7.1 64.9 100 40 48.5 11.5 14.2 9.4 64.9 100 50 48.5 11.5 11.8 11.8 64.9 100

Compressive strength according to blast furnace slag replacement rate Blast furnace slag replacement rate (%) Experiment count 3-day compressive strength (kgf / cm ² ) 7 days compressive strength (kgf / cm ² ) A B C Average A B C Average 0 One 245 246 285 259 260 294 256 270 2 268 294 285 282 263 252 326 281 3 295 241 289 275 232 288 253 258 Average: 272, Standard Deviation: 21, Highest Value: 295, Lowest Value: 241 Average: 269, Standard Deviation: 26, Highest Value: 326, Lowest Value: 232 20 One 283 273 262 273 261 276 254 264 2 274 266 287 276 279 316 229 275 3 264 266 299 276 231 280 284 265 Average: 275, Standard Deviation: 12, Highest Value: 299, Lowest Value: 262 Average: 268, Standard Deviation: 26, Highest Value: 316, Min: 229 30 One 245 253 234 244 229 225 224 226 2 259 255 264 259 279 252 252 261 3 271 288 262 273 295 313 303 304 Average: 259, Standard Deviation: 14, Highest Value: 288, Lowest Value: 234 Average: 263, Standard Deviation: 33, Highest Value: 313, Lowest Value: 224 40 One 267 214 233 238 246 265 281 264 2 224 231 237 231 321 171 279 257 3 213 225 223 220 251 273 251 258 Average: 230, Standard Deviation: 15, Highest Value: 267, Lowest Value: 213 Average: 260, Standard Deviation: 38, Highest Value: 321, Lowest Value: 171 50 One 201 220 213 211 262 176 265 235 2 241 233 223 232 262 264 236 254 3 201 188 228 206 252 221 236 Average: 272, Standard Deviation: 21, Highest Value: 295, Lowest Value: 241 Average: 242, Standard Deviation: 29, Highest Value: 265, Lowest Value: 176

Example 2 Preparation of Secondary Concrete Product According to Change of Pressing Force of Vibration Press Machine

Since the construction secondary products are produced by the vibration compression molding machine, the quality of the product is also affected by the vibration time and the pressing force of the vibration compression molding machine, so it is necessary to set the optimum condition for this. In this embodiment, the vibration time in accordance with the experimental design shown in Table 4 was carried out an experiment by the unification 5 seconds, and the pressing force 6, 8kgf / cm ^{2 2} level. Mixing levels were applied for blast furnace slag 30% replacement and for ordinary portland cement only. The specimen was prepared by using a 5 × 5 × 5 cm Cubic specimen using a vibration compression molding machine, and the specimen was cured after standing for 4 hours in a room at 20 ° C. after molding. Change in curing temperature was raised to 80 ℃ at a rate of 10 ℃ / hr and then stopped heating and lowered to 40 ℃ at a rate of 10 ℃ / hr. At 24 hours, the first measurement age, the curing tank was opened to dissipate naturally, so that the total curing time was 840 ℃ hr, and the humidity was maintained at RH 100%. Compressive strength measurement was carried out in the same manner as in Example 1.

As a result, as shown in Table 5 and Figures 3 and 4, the compressive strength increased as the pressing force of the vibration compression molding machine increased. And cement substituted with blast furnace slag showed the same level of strength at pressing force of 8kgf / cm ² but lower at pressing force of 6kgf / cm ² compared with cement using only portland cement.

Experiment plan Blast furnace slag replacement rate (%) Press force (kgf / cm ² ) Vibration time (seconds) Metric 030 68 5 1-day compressive strength

Compressive strength according to blast furnace slag replacement rate and pressing force Blast furnace slag replacement rate (%) Press force (kgf / cm ² ) Daily compressive strength (kgf / cm ² ) Average compressive strength (kgf / cm ² ) 0 6 246 199 157 201 8 171 241 235 215 30 6 223 161 200 195 8 249 185 220 218

Example 3: Preparation of secondary concrete products according to the vibration time change of the vibration press molding machine

In order to examine the change in compressive strength according to the vibration time of the vibration compression molding machine which is a method of manufacturing high-strength concrete secondary products, the experimental plan is as shown in Table 6, and the experimental plan is as shown in Table 6 The vibration time was changed to 5, 10, and 15 seconds with the pressing force constant at ⁸ kgf / cm ² showing high compressive strength at ² . The measurement age of the test specimen was 1 day of age, which is the quality control day in the field. The method of measuring the materials used, the equipment used, the formulation, the specimen preparation method, the curing and the compressive strength were the same as in Example 2.

As a result of the experiment, as shown in Table 7 and FIG. 5, the change in the compressive strength according to the vibration time showed the highest compressive strength when the vibration time was 10 seconds, and the vibration time was 15 seconds when the vibration time was 15 seconds. The compressive strength was found to be lowered.

Experiment plan Blast furnace slag replacement rate (%) Press force (kgf / cm ² ) Vibration time (seconds) Metric 0 8 51015 Compressive strength

Compressive strength according to frequency Vibration time (seconds) Daily compressive strength (kgf / cm ² ) Average compressive strength (kgf / cm ² ) Experiment 1 Experiment 2 Experiment 3 5 406 307 326 346 10 395 383 364 381 15 354 277 237 289

Example 4 Manufacture of Secondary Concrete Products by Variation of Pressing Force of Vibration Press Machine

As shown in Table 7 of Example 3, the oscillation time was found to be 10 seconds, and therefore, in this example, the pressing force was changed to be more varied than that performed in Example 3 to optimize the pressing force. As shown in Table 8, the experimental plan was set to two levels of pressing force 0, 6, 8, 12kgf / cm ² and vibration time 5, 10 seconds. The method of measuring the materials used, the equipment used, the formulation, the specimen preparation method, the curing and the compressive strength were carried out in the same manner as in Example 2. As a result of the experiment, as shown in Table 9, 10 and Figs. 6 and 7, the compressive strength increases as the pressing force increases up to 8 kgf / cm ² , but the compressive strength at ¹² kgf / cm ² is applied regardless of the vibration time of 5 seconds and 10 seconds. Fell.

Experiment plan Press force (kgf / cm ² ) Vibration time (seconds) Metric 06812 510 1-day compressive strength

Compressive strength according to pressing force Press force (kgf / cm ² ) Vibration time (seconds) Daily compressive strength (kgf / cm ² ) Average compressive strength (kgf / cm ² ) Experiment 1 Experiment 2 Experiment 3 0 5 158 217 207 194 6 243 329 262 215 8 273 318 348 313 12 292 298 295 295

Compressive strength according to pressing force Press force (kgf / cm ² ) Vibration time (seconds) Daily compressive strength (kgf / cm ² ) Average compressive strength (kgf / cm ² ) Experiment 1 Experiment 2 Experiment 3 0 10 206 229 195 210 6 319 285 348 317 8 311 356 371 346 12 288 278 292 286

Comparative Example 1: Comparison of density and compressive strength with conventional products

In this comparative example, the relationship between the density of the conventional product and the test specimen prepared in Example 4 and the compressive strength was compared.

As a result of the experiment, the test body prepared in Example 4 is almost linearly increased in density with increasing pressure. As shown in Table 11 and Figure 8 it can be seen that the compressive strength is higher and the density is smaller than the existing product, the density of the test specimen showing the highest compressive strength was expressed in the range of 2.05 ~ 2.25. In summary, the optimum pressure and vibration time for the production of high-strength concrete secondary products were found to be 8 kgf / cm ² and 10 second vibration time.

Comparison of density and compressive strength with existing products Comparison of density and compressive strength of existing products and test specimens Press force 0kgf / cm ² Press force 6kgf / cm ² Press force 8kgf / cm ² Press force 12kgf / cm ² Existing Product Density (t / m ³ ) Compressive strength (kgf / cm ² ) Density (t / m ³ ) Compressive strength (kgf / cm ² ) Density (t / m ³ ) Compressive strength (kgf / cm ² ) Density (t / m ³ ) Compressive strength (kgf / cm ² ) Density (t / m ³ ) Compressive strength (kgf / cm ² ) 1.97 206 2.06 319 2.07 311 2.13 288 2.17 186 1.99 229 2.09 285 2.11 356 2.11 278 2.43 388 1.99 195 2.09 348 2.08 371 2.23 296

Example 5: Investigation of the appropriate rate of blast furnace slag for the production of high-strength concrete secondary products

As shown in Table 12, this Example is to examine the appropriate blast furnace slag replacement rate for the development of high-strength concrete secondary products, W / B 28%, blast furnace slag replacement rate is 0, 20, 30, 40% 4 The compressive strength characteristics according to the blast furnace slag replacement rate were reviewed at each age. The molding method of the test body was subjected to the vibration press molding with a vibration time of 10 seconds and a pressing force of 8 kgf / cm ² based on the vibration time and the pressure test results, and the number of experiments was repeated five times. The method of measuring the materials used, the equipment used, the formulation, the specimen preparation method, the curing and the compressive strength were carried out in the same manner as in Example 2. The formulation is as shown in Table 13.

As a result of the experiment, as shown in Table 14 and 9, 10, 11, 12, the compressive strength is increased as the blast furnace slag replacement rate increases. The standard deviations and coefficients of variation by experimental order show that the standard deviation of Portland cement decreases with time, but the cement substituted for blast furnace slag has a high variation in compressive strength.

Experiment plan Blast furnace slag replacement rate (%) W / B (%) Metric Remarks 0 28 Compressive strength age (1 day, 3 days, 7 days) Number of experiments: 5 times Vibration time: 10 seconds Pressure: 8 kgf / cm ² 20 30 40

Formulation Design Table Blast furnace slag replacement rate (%) cement(%) Blast furnace slag (%) Stone powder (%) sand(%) water(%) 0 23.69 - 18.35 49.99 6.81 20 18.952 4.738 18.35 49.99 6.81 30 16.583 7.107 18.35 49.99 6.81 40 14.214 9.476 18.35 49.99 6.81

1, 2, 3, 4, 5th compressive strength according to slag replacement rate SL replacement rate (%) Number of experiments Daily compressive strength (kgf / cm ² ) Average 3-day compressive strength (kgf / cm ² ) Average 7 days compressive strength (kgf / cm ² ) Average a b c d a b c d a b c 0 One 259 296 314 300 292 316 399 335 340 348 370 357 369 366 2 237 271 289 322 280 333 373 361 319 347 431 340 371 381 3 348 336 313 345 336 434 384 329 385 383 317 326 426 356 4 457 322 347 402 382 292 300 354 494 360 294 347 463 368 5 393 396 375 454 404 265 291 391 411 340 357 419 416 397 Average: 339, σ: 48.5, Coefficient of variation: 14.31% Average: 356, σ: 15.1, Coefficient of variation: 4.24% Average: 368, σ: 10.3, Coefficient of variation: 2.8% 20 One 344 389 323 345 350 308 331 310 313 315 323 355 386 354 2 345 374 404 371 374 389 437 432 421 420 433 480 494 469 3 270 377 288 369 326 403 449 460 490 451 318 370 456 381 4 399 445 350 372 392 385 399 330 498 403 389 381 498 423 5 416 371 382 418 397 385 350 398 380 378 415 354 470 413 Average: 364, σ: 23.4, Coefficient of variation: 6.43% Average: 393, σ: 45.8, Coefficient of variation: 11.65% Average: 401, σ: 49.1, Coefficient of variation: 12.24% 30 One 438 390 468 415 428 350 416 372 408 387 450 472 532 484 2 429 425 434 426 429 557 530 571 561 555 487 518 555 520 3 352 387 322 339 350 415 493 399 411 430 351 354 488 397 4 437 460 415 458 443 542 455 404 520 481 264 406 565 412 5 353 323 316 389 345 341 344 388 491 391 447 482 570 500 Average: 399, σ: 42.4, Coefficient of variation: 10.63% Average: 449, σ: 63, Coefficient of variation: 14.30% Average: 467, σ: 51.6, Coefficient of variation: 11.05% 40 One 311 313 295 290 302 381 357 353 333 356 454 481 584 506 2 505 411 429 388 433 465 502 469 511 487 567 562 482 537 3 348 385 412 435 395 432 418 478 465 448 408 440 345 398 4 447 419 462 558 472 454 521 362 379 429 383 370 428 394 5 290 288 324 407 327 388 379 442 476 421 380 432 512 441 Average: 386, σ: 63.6, Coefficient of variation: 16.48% Average: 428, σ: 42.7, Coefficient of variation: 9.98% Average: 480, σ: 59.6 Coefficient of variation: 12.42%

As described above, the blast furnace slag, which is an industrial waste, is replaced with 20 to 40% of cement under conditions of a vibration time of 5 to 10 seconds and a pressing force of 6 to 12 kgf / cm ² as described above. One concrete secondary product of the present invention has an excellent effect of improving the compressive strength up to 500kgf / cm ² is a very useful invention in the construction materials manufacturing industry.

Claims (2)

The industrial waste blast furnace slag is replaced by 20-40% instead of cement under the condition that the ratio of water-binding material (W / B) is 28%, and a vibration compression molding machine is molded with a vibration time of 5 to 10 seconds and a pressing force of 6 to 12 kgf / cm ² Method for producing a concrete secondary product characterized in that. A secondary concrete product produced by the method of claim 1.