WHOLE-GRANULATION STEEL SLAG PAVEMENT BASE COURSE MATERIAL FOR HEAVY-LOAD PAVEMENT

Abstract

The invention provides a whole-granulation steel slag pavement base course material for a heavy-load pavement, which is prepared by uniformly mixing dry materials with water. The dry materials include a binder and a steel slag aggregate. The percentages in total mass of the binder and the steel slag aggregate are as follows: the binder is 3.4% to 5.0%, and the steel slag aggregate is 95.0% to 96.6%. The binder is prepared by mixing cement with steel slag micropowder according to a certain proportion, wherein the mass percentages of the cement and the steel slag micropowder are as follows: the cement is 70% to 90%, and the steel slag micropowder is 10% to 30%. The water accounts for 5% to 6% of the total mass of the dry materials.

Claims

1. A whole-granulation steel slag pavement base course material for a heavy-load pavement, comprising: being prepared by uniformly mixing dry materials with water, the dry materials comprise a binder and a steel slag aggregate, wherein percentages in a total mass of the binder and the steel slag aggregate are as follows: the binder is 3.4% to 5.0%, and the steel slag aggregate is 95.0% to 96.6%; the binder is prepared by mixing cement with steel slag micropowder according to a certain proportion, mass percentages of the cement and the steel slag micropowder are as follows: the cement is 70% to 90%, and the steel slag micropowder is 10% to 30%, and the water accounts for 5% to 6% of a total mass of the dry materials.

2. The whole-granulation steel slag pavement base course material for the heavy-load pavement according to claim 1, wherein the cement in the binder is P.C 32.5 composite Portland cement.

3. The whole-granulation steel slag pavement base course material for the heavy-load pavement according to claim 1, wherein the steel slag micropowder in the binder is finely ground converter steel slag powder with certain cementitious activity, and has a specific surface area not less than 400 m.sup.2/kg, a passing rate is 90% or above in sieve pores with a pore size of 0.075 mm, and the content of free calcium oxide (f-CaO) does not exceed 3.0 wt %.

4. The whole-granulation steel slag pavement base course material for the heavy-load pavement according to claim 1, wherein the steel slag aggregate in the dry materials is thermally disintegrated steel slag obtained by smashing waste slag discharged from a steel mill and performing magnetic separation according to a thermal disintegrating method, and has an apparent density not less than 3.2 g/cm.sup.3; the steel slag is divided into a coarse steel slag aggregate and a fine steel slag aggregate according to sieve pores of 4.75 mm, and the steel slag has grades of: 15 wt % to 18 wt % for a pore size of 19 mm to 26.5 mm, 20 wt % to 24 wt % for a pore size of 9.5 mm to 19 mm, 19 wt % to 21 wt % for a pore size of 4.75 mm to 9.5 mm, 13 wt % to 15 wt % for a pore size of 2.36 mm to 4.75 mm, and 23 wt % to 27 wt % for a pore size of 0 mm to 2.36 mm.

5. The whole-granulation steel slag pavement base course material for the heavy-load pavement according to claim 1, wherein immersion expansion ratios of the course steel slag aggregate and the fine steel slag aggregate do not exceed 2.0%.

6. The whole-granulation steel slag pavement base course material for the heavy-load pavement according to claim 1, wherein the content of f-CaO in the steel slag aggregate does not exceed 3.0 wt %.

7. The whole-granulation steel slag pavement base course material for the heavy-load pavement according to claim 1, wherein the water is ordinary drinking water.

8. The whole-granulation steel slag pavement base course material for the heavy-load pavement according to claim 1, wherein being prepared by a method through the following steps: 1) respectively selecting the binder and the steel slag aggregate according to the following requirements: the percentages in the total mass of the binder and the steel slag aggregate are as follows: the binder is 3.4% to 5.0%, and the steel slag aggregate is 95.0% to 96.6%, wherein the binder is prepared by mixing the cement with the steel slag micropowder according to a certain proportion, the mass percentages of the cement and the steel slag micropowder are as follows: the cement is 70% to 90%, and the steel slag micropowder is 10% to 30%; the steel slag aggregate has grades of: 15 wt % to 18 wt % for a pore size of 19 mm to 26.5 mm, 20 wt % to 24 wt % for a pore size of 9.5 mm to 19 mm, 19 wt % to 21 wt % for a pore size of 4.75 mm to 9.5 mm, 13 wt % to 15 wt % for a pore size of 2.36 mm to 4.75 mm, and 23 wt % to 27 wt % for a pore size of 0 mm to 2.36 mm; 2) placing the steel slag aggregate in an environment at 105° C.±5° C., and drying the aggregate for generally not shorter than 4 hour to 6 hour until a constant weight is achieved; 3) taking 5 parts of the dry materials according to a mass ratio, setting 5 groups of water contents in advance, with a difference of 0.5% to 1.5% in sequence, then adding water into the dry materials respectively to obtain a mixture, and stirring the mixture until the mixture is uniform, then performing heavy compaction, testing an actual water content and a maximum dry density, and finally drawing a dry density curve to obtain an optimal water content and a maximum dry density; 4) taking an appropriate amount of the dry materials according to a certain mass ratio, adding water required for immersion, then mixing the dry materials with the water to obtain a mixture, stirring the mixture for 5 minute to 10 minute until the mixture is uniform, and putting the uniformly mixed mixture into a closed container for immersion for 6 hour to 12 hour, wherein the content of the added water is 1% to 2% less than the optimal water content in the step 3; 5) adding an appropriate amount of water into the immersed mixture in the step 4 to reach the optimal water content, stirring the water and the mixture for 5 minute to 10 minute, then adding a uniformly mixed binder to obtain a mixture, and performing secondary stirring for 5 minute to 10 minute until the mixture is uniformly mixed; and 6) within 1 hour after adding the binder, uniformly filling a mold with a stirred mixture, controlling the density, and performing static press molding to obtain a base course material test sample.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to describe the technical solutions of the examples of the present invention more clearly, accompanying drawings of the examples are briefly described below.

[0021] FIG. 1 is an unconfined compressive strength diagram of a base course material of each preferable example of the present invention; and

[0022] FIG. 2 is a test result diagram of a 60d total dry shrinkage coefficient of a base course material of each preferable example of the present invention.

DETAILED DESCRIPTION

[0023] The following is a detailed description of specific implementation modes of the present invention. As a part of the specification, the principle of the invention is described through examples, and other aspects, features, and advantages of the present invention will become clear from this detailed description.

[0024] In the following examples, a specific surface area of steel slag micropowder used is 450 m.sup.2/kg, a passing rate is 91% in sieve pores with a pore size of 0.075 mm, and the content of free calcium oxide (f-CaO) is 2.1 wt %.

[0025] In the following examples, the steel slag aggregate used is thermally disintegrated steel slag, and the aging time is 12 months or longer. The apparent relative density is 3.6 to 3.7 g/cm.sup.3, and a crushing value is 12.1%. The steel slag is divided into a coarse steel slag aggregate and a fine steel slag aggregate according to sieve pores of 4.75 mm. The content of f-CaO in the fine steel slag aggregate is 1.12 wt %, and the content of CaO in the course steel slag aggregate is 1.51 wt %.

[0026] In the following examples, the water used is ordinary drinking water.

Example 1

[0027] According to a whole-granulation steel slag pavement base course material for a heavy-load pavement, the percentages in total mass of a binder and a steel slag aggregate in dry materials are as follows: the binder is 4.8%, and a course steel slag aggregate is 95.2%. The binder is prepared by mixing cement with steel slag micropowder, and a mass ratio of the cement to the steel slag micropowder is 9:1. The steel slag has grades of: 17 wt % for a pore size of 19 mm to 26.5 mm, 23 wt % for a pore size of 9.5 mm to 19 mm, 20 wt % for a pore size of 4.75 mm to 9.5 mm, 15 wt % for a pore size of 2.36 mm to 4.75 mm, and 25 wt % for a pore size of 0 mm to 2.36 mm.

[0028] A preparation method of the above whole-granulation steel slag pavement base course material for the heavy-load pavement includes the following steps.

1) A steel slag aggregate and a binder are weighed according to the above mixing ratio, wherein synthesizing grades of the steel slag aggregate refer to Table 1.
2) The steel slag aggregate is placed in an environment at 105° C.±5° C., and the aggregate is dried (for generally not shorter than 4 hour to 6 hour) until a constant weight is achieved.
3) 5 parts of an appropriate amount of dry materials are taken according to the mass ratio, and water contents of 3%, 4%, 5%, 6% and 7% are set in advance; then, water is added into the dry materials respectively to obtain a mixture and the mixture is stirred until the mixture is uniform; and then, heavy compaction is performed, an actual water content and a maximum dry density are tested, and finally, a dry density curve is drawn to obtain an optimal water content. The optimal water content refers to Table 2.
4) An appropriate amount of the dry materials are taken according to a certain mass ratio; water required for immersion (the water content added at this time should be 1% to 2% less than the optimal water content in the step 3) is taken; the dry materials and the water are mixed to obtain a mixture and the mixture is stirred for 5 minute to 10 minute until the mixture is uniform; and the uniformly mixed mixture is put into a closed container for immersion for 6 hour to 12 hour.
5) An appropriate amount of water is added into the immersed mixture in the step 4 to reach the optimal water content, and the water and the mixture are stirred for 5 minute to 10 minute; and then, a uniformly mixed binder is added to obtain a mixture, and secondary stirring is performed for 5 minute to 10 minute until the mixture is uniformly stirred.
6) Within 1 hour after adding the binder, a mold is uniformly filled with the stirred mixture, the density is controlled, and static press molding is performed to obtain a base course material test sample.

Example 2

[0029] According to a whole-granulation steel slag pavement base course material for a heavy-load pavement, the percentages in total mass of a binder, a natural aggregate and a steel slag aggregate in dry materials are as follows: the binder is 4.3%, and a course steel slag aggregate is 95.7%. The binder is prepared by mixing cement with steel slag micropowder, and a mass ratio of the cement to the steel slag micropowder is 7:3. The steel slag has grades of: 16 wt % for a pore size of 19 mm to 26.5 mm, 24 wt % for a pore size of 9.5 mm to 19 mm, 20 wt % for a pore size of 4.75 mm to 9.5 mm, 14 wt % for a pore size of 2.36 mm to 4.75 mm, and 26 wt % for a pore size of 0 mm to 2.36 mm.

[0030] A preparation method of the above whole-granulation steel slag pavement base course material for the heavy-load pavement is the same as the preparation method in Example 1.

Example 3

[0031] According to a whole-granulation steel slag pavement base course material for a heavy-load pavement, the percentages in total mass of a binder, a natural aggregate and a steel slag aggregate in dry materials are as follows: the binder is 3.4%, and the steel slag aggregate is 96.6%. The binder is prepared by mixing cement with steel slag micropowder, and a mass ratio of the cement to the steel slag micropowder is 9:1. The steel slag has grades of: 16 wt % for a pore size of 19 mm to 26.5 mm, 24 wt % for a pore size of 9.5 mm to 19 mm, 20 wt % for a pore size of 4.75 mm to 9.5 mm, 15 wt % for a pore size of 2.36 mm to 4.75 mm, and 25 wt % for a pore size of 0 mm to 2.36 mm.

[0032] A preparation method of the above whole-granulation steel slag pavement base course material for the heavy-load pavement is the same as the preparation method in Example 1.

Comparative Example

[0033] A pure natural aggregate pavement base course material is prepared by mixing straight cement and a natural aggregate in mass percentages of 4.7% and 95.3%. The natural aggregate has grades of: 18 wt % for a pore size of 19 mm to 26.5 mm, 24 wt % for a pore size of 9.5 mm to 19 mm, 20 wt % for a pore size of 4.75 mm to 9.5 mm, 12 wt % for a pore size of 2.36 mm to 4.75 mm, and 26 wt % for a pore size of 0 mm to 2.36 mm.

[0034] A preparation method of the above base course material of the comparative example is the same as the preparation method in Example 1.

TABLE-US-00001 TABLE 1 C-B-1 Screening and Synthesizing Grades mass percentage (%) passing through sieve pores (mm) of a square pore sieve Sieve Pore 26.5 19 16 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 Example 1 100 84.4 77.0 68.9 58.1 37.6 26.4 16.0 12.0 8.1 5.2 2.9 Example 2 100 85.2 76.7 69.6 58.1 39.9 25.8 17.8 13.4 8.1 5.4 2.9 Example 3 100 85.2 76.7 69.6 58.1 39.9 25.2 17.2 12.9 7.8 5.2 2.8 Comparative 100 85.4 75.2 67.5 58.6 39.9 25.2 17.5 13.2 8.0 5.3 2.7 Example

TABLE-US-00002 TABLE 2 Optimal Water Content and Maximum Dry Density Example Example Example Comparative Compaction Test 1 2 3 Example Optimal Water 5.7 5.5 5.8 5.1 Content % Maximum Dry Density 2.885 2.856 2.833 2.312 g/cm.sup.3
7d and 28d unconfined compressive strength tests are carried out on the base course materials of the three examples and the comparative example according to the requirements in the standard Test Methods of Materials Stabilized with Inorganic Binders for Highway Engineering (JTG/E51-2009), and test results are as shown in FIG. 1.

[0035] It can be seen from FIG. 1 that the 7d and 28d unconfined compressive strength of the three examples is much higher than that of the comparative example, which indicates that the steel slag aggregate base course material provided by the present invention is featured with high strength and is applicable to the heavy-load pavement.

[0036] Dry shrinkage tests are carried out on the base course materials of the three examples and the comparative example according to the requirements in the standard Test Methods of Materials Stabilized with Inorganic Binders for Highway Engineering (JTG/E51-2009), and test results of 60d total dry shrinkage coefficients are as shown in FIG. 2.

[0037] It can be seen from FIG. 2 that the total dry shrinkage coefficients of the three examples are obviously lower than the total dry shrinkage coefficient of the comparative example, which indicates that the whole-granulation steel slag aggregate base course material provided by the present invention is featured with low dry shrinkage.

[0038] The various raw materials listed in the present invention, upper and lower limits and range values of the various raw materials of the present invention, and upper and lower limits and range values of process parameters (such as temperature and time) can all implement the present invention, and examples are not stated one by one herein.

[0039] The above is only the preferred implementation modes of the present invention, and of course, cannot be used to limit the claims of the present invention. It should be noted that those of ordinary skill in the art can further make several improvements and changes without departing from the principles of the present invention. These improvements and changes shall all fall within the protection scope of the present invention.