CN114067931B - Asphalt mixture aggregate segregation pre-judging method - Google Patents
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- 239000010426 asphalt Substances 0.000 title claims abstract description 217
- 238000005204 segregation Methods 0.000 title claims abstract description 158
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- 238000005056 compaction Methods 0.000 description 16
- 239000011800 void material Substances 0.000 description 13
- 230000006378 damage Effects 0.000 description 10
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- 239000004567 concrete Substances 0.000 description 1
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- 238000000354 decomposition reaction Methods 0.000 description 1
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- 239000008187 granular material Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
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Abstract
The invention relates to the field of road engineering, in particular to an aggregate segregation pre-judging method for asphalt mixtures, which comprises the following steps: step S1, establishing an asphalt mixture aggregate segregation pre-judging model; s2, establishing an asphalt mixture aggregate segregation evaluation standard; and S3, calculating an aggregate composite texture segregation tendency index STI TX and an aggregate composite edge segregation tendency index STI GA of the asphalt mixture to be pre-judged, comparing the aggregate composite texture segregation tendency index STI TX with an asphalt mixture aggregate segregation evaluation standard, and pre-judging the aggregate segregation degree of the asphalt mixture. The invention judges whether the aggregate segregates from the micro level, realizes the transition of aggregate segregating from 'back evaluation' to 'front prejudgment', and further can control the aggregate segregating of the asphalt mixture in advance.
Description
Technical Field
The invention relates to the field of road engineering, in particular to an aggregate segregation pre-judging method for asphalt mixtures.
Background
Asphalt mixtures are multiphase particulate materials composed of aggregate, asphalt binder, and voids. The spreading and compacting of the asphalt mixture is the process of converting the particle system coated with asphalt from loose flow state to stable forming state through metastable transition state. When the aggregate segregates, the asphalt mixture breaks, resulting in multiple road surface defects and reduced durability.
Disclosure of Invention
The invention aims to provide an aggregate segregation pre-judging method for asphalt mixtures, which is used for judging whether aggregates segregate from a micro level, so that the transition from 'post evaluation' to 'pre-judging' of aggregate segregations is realized, and the aggregate segregations of the asphalt mixtures can be controlled in advance.
In order to achieve the above purpose, the present invention is realized by the following technical scheme.
The pre-judging method for the segregation of asphalt mixture aggregate comprises the following steps:
step S1, an aggregate segregation pre-judging model of the asphalt mixture is established, wherein the aggregate segregation pre-judging model is shown in a formula (1) and a formula (2);
In the formula (1), STI TX is the aggregate composite texture segregation trend index of the asphalt mixture, CI TX is the composite texture index of the asphalt mixture, Is the maximum value of the composite texture index of the asphalt mixture;
In the formula (2), STI GA is the aggregate composite angular segregation tendency index of the asphalt mixture, CI GA is the composite angular index of the asphalt mixture, Is the maximum value of the composite angular index of the asphalt mixture;
s2, establishing an asphalt mixture aggregate segregation evaluation standard;
When the aggregate composite texture segregation tendency index STI TX of the asphalt mixture has values of 0 to 0.2, 0.2 to 0.25, 0.25 to 0.3, 0.3 to 0.35 and 0.35 to 1, the aggregate segregation degree of the asphalt mixture corresponds to fine aggregate segregation, no segregation, coarse aggregate mild segregation, coarse aggregate moderate segregation and coarse aggregate severe segregation respectively; when the aggregate compound angular segregation tendency index STI GA of the asphalt mixture has values of 0 to 0.6, 0.6 to 0.7, 0.7 to 0.8, 0.8 to 0.9 and 0.9 to 1, the aggregate segregation degree of the asphalt mixture corresponds to fine aggregate segregation, no segregation, coarse aggregate mild segregation, coarse aggregate moderate segregation and coarse aggregate severe segregation respectively;
And S3, calculating an aggregate composite texture segregation tendency index STI TX and an aggregate composite edge segregation tendency index STI GA of the asphalt mixture to be pre-judged, comparing the aggregate composite texture segregation tendency index STI TX with an asphalt mixture aggregate segregation evaluation standard, and pre-judging the aggregate segregation degree of the asphalt mixture.
Compared with the prior art, the invention has the beneficial effects that: the aggregate segregation tendency pre-judging method is constructed by adopting the composite geometric characteristic parameters, whether the aggregate segregates or not is judged from the micro level, the purpose of judging whether the aggregate segregates or not is changed from 'post evaluation' to 'pre-judging', and the purpose of controlling the aggregate segregating of the asphalt mixture in advance is achieved.
Drawings
The invention will now be described in further detail with reference to the drawings and to specific examples.
FIG. 1 is a flow chart of the aggregate segregation pre-determination method of the asphalt mixture of the present invention;
FIG. 2 is a graph showing the grading of five asphalt mixtures in an embodiment of the method for pre-judging aggregate segregation of asphalt mixtures according to the present invention; the abscissa is the sieve pore diameter, and the ordinate is the sieve pore passing rate;
FIG. 3 is a graph of the composite shape index CI SP and compaction energy index CEI for five bituminous mixtures in an embodiment of the bituminous mixture aggregate segregation prediction method of the present invention; the abscissa is the composite shape index CI SP of the asphalt mixture, and the ordinate is the compaction energy index CEI;
FIG. 4 is a graph of composite texture index CI TX versus compaction energy index CEI for five bituminous mixtures in an embodiment of the bituminous mixture aggregate segregation prediction method of the present invention; the abscissa is the composite texture index CI TX of the asphalt mixture, and the ordinate is the compaction energy index CEI;
FIG. 5 is a graph of the composite angular index CI GA and compaction energy index CEI for five bituminous mixtures in an embodiment of the bituminous mixture aggregate segregation prediction method of the present invention; the abscissa is the composite angular index CI GA of the asphalt mixture, and the ordinate is the compaction energy index CEI;
FIG. 6 is a graph showing the relationship between the composite shape index CI SP of five asphalt mixtures and the number of damages and creep rate of the asphalt mixtures in the embodiment of the asphalt mixture aggregate segregation pre-judging method of the present invention; the abscissa is the composite shape index CI SP of the asphalt mixture, and the ordinate is the damage times and creep rate of the asphalt mixture from left to right;
FIG. 7 is a graph of composite texture index CI TX for five bituminous mixtures versus the number of failures and creep rates of the bituminous mixtures for an embodiment of the bituminous mixture aggregate segregation pre-determined method of the present invention; the abscissa is the composite texture index CI TX of the asphalt mixture, and the ordinate is the damage times and creep rate of the asphalt mixture from left to right;
FIG. 8 is a graph showing the relationship between the composite angular index CI GA of five asphalt mixtures and the number of damages and creep rate of the asphalt mixtures in the embodiment of the asphalt mixture aggregate segregation pre-judging method of the present invention; the abscissa is the composite angular index CI GA of the asphalt mixture, and the ordinate is the damage times and creep rate of the asphalt mixture from left to right;
FIG. 9 is a graph showing the void ratio of five asphalt mixtures according to the embodiment of the aggregate segregation prediction method of the present invention, and the corresponding number of flaking, rutting depth and flaking rate; the abscissas are void ratios of the five asphalt mixtures, and the abscissas are the number of stripping times, the rutting depth and the stripping rate corresponding to the asphalt mixtures from left to right;
FIG. 10 is a graph showing the relationship between the void ratios of five asphalt mixtures and the corresponding composite shape index CI SP, composite texture index CI TX and composite corner index CI GA in an embodiment of the asphalt mixture aggregate segregation pre-judging method of the invention; the abscissa is the void ratio of the asphalt mixture, and the ordinate is the composite shape index CI SP, the composite texture index CI TX and the composite edge index CI GA corresponding to the asphalt mixture from left to right respectively;
FIG. 11 is a comparative bar graph showing the tensile strength R T, the tensile strain at failure ε T, and the stiffness at failure modulus S T for five bituminous mixtures in an example of the bituminous mixture aggregate segregation pre-determination method of the present invention; the abscissa indicates the asphalt mixture type, and the ordinate indicates, from left to right, the tensile strength R T, the tensile strain at break epsilon T, and the stiffness at break modulus S T, respectively, corresponding to the asphalt mixture.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention.
The pre-judging method for the segregation of asphalt mixture aggregate comprises the following steps:
step S1, an aggregate segregation pre-judging model of the asphalt mixture is established, wherein the aggregate segregation pre-judging model is shown in a formula (1) and a formula (2);
In the formula (1), STI TX is the aggregate composite texture segregation trend index of the asphalt mixture, CI TX is the composite texture index of the asphalt mixture, Is the maximum value of the composite texture index of the asphalt mixture;
In the formula (2), STI GA is the aggregate composite angular segregation tendency index of the asphalt mixture, CI GA is the composite angular index of the asphalt mixture, Is the maximum value of the composite angular index of the asphalt mixture;
specifically, the composite texture index CI TX of the asphalt mixture is shown as formula (4);
In the formula (4):
a i is the percentage of screen residue of the ith grade aggregate in the grading design;
n is the particle size of all aggregates in the grading design;
m is the grain size grade number of coarse aggregate used in grading design;
g i is the volumetric relative density of the i-th grade aggregate;
d i is the average particle size of the i-th grade aggregate, Wherein P i+1 is the mesh size of the i+1st set;
V wi is the weighted volume of aggregate particle shape, V Wi＝Vci×SPi+Vsi×(1-SPi), wherein the cube volume: Sphere volume:
SA wi is the weighted surface area of the aggregate particle shape, SA Wi＝SAci×SPi+SAsi×(1-SPi), where the cube surface area: Sphere surface area:
TX i is a surface texture index;
GA i is the angular gradient of the i-th grade aggregate;
Specifically, the composite angular index CI GA of the asphalt mixture is shown in formula (5);
The compound angular index CI GA is shown in formula (5);
In formula (5):
a i is the percentage of screen residue of the ith grade aggregate in the grading design;
n is the particle size of all aggregates in the grading design;
m is the grain size grade number of coarse aggregate used in grading design;
g i is the volumetric relative density of the i-th grade aggregate;
d i is the average particle size of the i-th grade aggregate, Wherein P i+1 is the mesh size of the i+1st set;
V wi is the weighted volume of aggregate particle shape, V Wi＝Vci×SPi+Vsi×(1-SPi), wherein the cube volume: Sphere volume:
GA i is the angular gradient of the i-th grade aggregate;
M is the total mass of mineral aggregates;
specifically, the maximum value of the composite texture index of the asphalt mixture Has a value of 2447.62397312175, the maximum value of the composite angular index of the asphalt mixtureHas a value of 40008.2752815776.
S2, establishing an asphalt mixture aggregate segregation evaluation standard;
When the aggregate composite texture segregation tendency index STI TX of the asphalt mixture has values of 0 to 0.2, 0.2 to 0.25, 0.25 to 0.3, 0.3 to 0.35 and 0.35 to 1, the aggregate segregation degree of the asphalt mixture corresponds to fine aggregate segregation, no segregation, coarse aggregate mild segregation, coarse aggregate moderate segregation and coarse aggregate severe segregation respectively; when the aggregate compound angular segregation tendency index STI GA of the asphalt mixture has values of 0 to 0.6, 0.6 to 0.7, 0.7 to 0.8, 0.8 to 0.9 and 0.9 to 1, the aggregate segregation degree of the asphalt mixture corresponds to fine aggregate segregation, no segregation, coarse aggregate mild segregation, coarse aggregate moderate segregation and coarse aggregate severe segregation respectively; the evaluation criteria for segregation of asphalt mixture aggregate are shown in Table 1.
TABLE 1 evaluation criteria for segregation of asphalt aggregates
The concrete values of the dimensionless composite texture index and the dimensionless composite edge index are divided according to compaction characteristics and road performance evaluation indexes of the segregated asphalt mixture, and an aggregate segregation evaluation standard table of the asphalt mixture is shown in table 1.
And S3, calculating an aggregate composite texture segregation tendency index STI TX and an aggregate composite edge segregation tendency index STI GA of the asphalt mixture to be pre-judged, comparing the aggregate composite texture segregation tendency index STI TX with an asphalt mixture aggregate segregation evaluation standard, and pre-judging the aggregate segregation degree of the asphalt mixture.
The building process of the asphalt mixture aggregate segregation pre-judging model comprises the following steps:
Step 1, designing asphalt mixtures with different segregation degrees.
Based on the AC-20 median asphalt mixture, the fine aggregate segregation asphalt mixture (F), the non-segregation asphalt mixture (N), the coarse aggregate mild segregation asphalt mixture (L), the coarse aggregate medium segregation asphalt mixture (M) and the coarse aggregate severe segregation asphalt mixture (H) are designed according to different grading by taking 4.75mm and 9.5mm as key sieve holes, and grading curves are shown in figure 1.
Step 2, calculating the composite geometric index of each asphalt mixture, including a composite shape index CI SP, a composite texture index CI TX and a composite edge index CI GA.
The composite shape index CI SP is shown as formula (3);
In the formula (3):
a i is the percentage of screen residue of the ith grade aggregate in the grading design;
n is the particle size of all aggregates in the grading design;
SP i is a granule sphericity index;
m is the grain size grade number of coarse aggregate used in grading design;
g i is the volumetric relative density of the i-th grade aggregate;
d i is the average particle size of the i-th grade aggregate, Wherein P i+1 is the mesh size of the i+1st set;
V wi is the weighted volume of aggregate particle shape, V Wi＝Vci×SPi+Vsi×(1-SPi), wherein the cube volume: Sphere volume:
C wi is the weighted perimeter of the aggregate particle shape, C Wi＝Cci×SPi+Csi×(1-SPi), wherein the cube perimeter: Perimeter of sphere:
the composite texture index CI TX is shown in formula (4);
In the formula (4):
a i is the percentage of screen residue of the ith grade aggregate in the grading design;
n is the particle size of all aggregates in the grading design;
m is the grain size grade number of coarse aggregate used in grading design;
g i is the volumetric relative density of the i-th grade aggregate;
d i is the average particle size of the i-th grade aggregate, Wherein P i+1 is the mesh size of the i+1st set;
V wi is the weighted volume of aggregate particle shape, V Wi＝Vci×SPi+Vsi×(1-SPi), wherein the cube volume: Sphere volume:
SA wi is the weighted surface area of the aggregate particle shape, SA Wi＝SAci×SPi+SAsi×(1-SPi), where the cube surface area: Sphere surface area:
TX i is a surface texture index;
GA i is the angular gradient of the i-th aggregate.
The compound angular index CI GA is shown in formula (5);
In formula (5):
a i is the percentage of screen residue of the ith grade aggregate in the grading design;
n is the particle size of all aggregates in the grading design;
m is the grain size grade number of coarse aggregate used in grading design;
g i is the volumetric relative density of the i-th grade aggregate;
d i is the average particle size of the i-th grade aggregate, Wherein P i+1 is the mesh size of the i+1st set;
V wi is the weighted volume of aggregate particle shape, V Wi＝Vci×SPi+Vsi×(1-SPi), wherein the cube volume: Sphere volume:
GA i is the angular gradient of the i-th grade aggregate;
m is the total mass of mineral aggregate.
And 3, performing asphalt mixture macroscopic performance tests on asphalt mixtures with each segregation degree, wherein the asphalt mixture macroscopic performance tests comprise a rotary compaction test, a immersed hamburg rutting test and an indirect tensile test.
In a rotary compaction test, evaluating compaction characteristics of asphalt mixtures through compaction energy indexes CEI to obtain compaction energy indexes CEI corresponding to five asphalt mixtures;
In a immersed hamburg rutting test, evaluating the high-temperature stability of asphalt mixtures according to the number of damage times and creep rate when the rutting depth is close to 20mm, and obtaining the number of damage times and creep rate corresponding to the five asphalt mixtures; evaluating the water stability of the asphalt mixture according to the number of times of peeling, the rut depth and the peeling rate corresponding to the peeling points, and obtaining the number of times of rolling, the rut depth and the peeling rate corresponding to the five asphalt mixtures;
In the indirect tensile test, the low-temperature crack resistance of the asphalt mixture was evaluated by tensile strength R T, tensile strain at break epsilon T and stiffness at break modulus S T, and tensile strength R T, tensile strain at break epsilon T and stiffness at break modulus S T corresponding to the five asphalt mixtures were obtained.
Step 4, preferably establishing an index of an asphalt mixture aggregate segregation pre-judging model: composite texture index CI TX and composite angular index CI GA.
Sub-step 4.1, analyzing the relevance of the composite geometric indexes of the five asphalt mixtures and compaction characteristics;
Referring to fig. 3, it can be seen that the composite shape index CI SP of the five asphalt mixtures has a poor linear dependence on the compaction energy index CEI;
Referring to fig. 4, it can be seen that the composite texture index CI TX of the five asphalt mixtures exhibited a better linear correlation with the compaction energy index CEI;
referring to fig. 5, it can be seen that the composite angular index CI GA of the five asphalt mixtures exhibited a better linear correlation with the compaction energy index CEI.
Sub-step 4.2, analyzing the relevance of the composite geometric indexes of the five asphalt mixtures and the high-temperature stability;
referring to fig. 6, it can be seen that, for the composite shape index CI SP, the number of breaks of the asphalt mixture tends to increase and then decrease with increasing asphalt mixture composite shape index CI SP (i.e., increasing asphalt mixture segregation degree), while the creep rate of the asphalt mixture tends to decrease and then increase with increasing asphalt mixture composite shape index CI SP (i.e., increasing asphalt mixture segregation degree); the destruction times and creep rate of the asphalt mixture respectively reach peak value and valley value under the composite shape index CI SP of the coarse aggregate light segregation asphalt mixture (L), and the composite shape index CI SP of the coarse aggregate light segregation asphalt mixture (L) is between 0.0185 and 0.019;
Referring to fig. 7, it can be seen that, for the composite texture index CI TX, the number of breaks of the asphalt mixture tends to increase and then decrease with increasing asphalt mixture composite texture index CI TX (i.e., increasing asphalt mixture segregation degree), while the creep rate of the asphalt mixture tends to decrease and then increase with increasing asphalt mixture composite texture index CI TX (i.e., increasing asphalt mixture segregation degree); the destruction times and creep rates of the asphalt mixture respectively reach peak values and valley values under the composite texture index CI TX of the coarse aggregate light segregation asphalt mixture (L), and the composite texture index CI TX of the coarse aggregate light segregation asphalt mixture (L) is near 600;
Referring to fig. 8, it can be seen that, for the composite angular index CI GA, the number of failures of the asphalt mixture tends to increase and then decrease with an increase in the asphalt mixture composite angular index CI GA (i.e., an increase in the segregation degree of the asphalt mixture), while the creep rate of the asphalt mixture tends to decrease and then increase with an increase in the asphalt mixture composite angular index CI GA (i.e., an increase in the segregation degree of the asphalt mixture); the destruction times and creep rate of the asphalt mixture respectively reach peak value and valley value under the composite angular index CI GA of the coarse aggregate light segregation asphalt mixture (L), and the composite angular index CI GA of the coarse aggregate light segregation asphalt mixture (L) is between 26000 and 27000;
In summary, the composite texture index CI TX and the composite angular index CI GA are larger, but the composite shape index CI SP is not much different for the coarse aggregate mild-segregation asphalt mixture (L) compared to the non-segregation asphalt mixture (N), which means that the total number of mineral aggregate particles of the coarse aggregate mild-segregation asphalt mixture (L) is equivalent to that of the non-segregation asphalt mixture (N), but the number of large-particle coarse aggregates of the coarse aggregate mild-segregation asphalt mixture (L) is slightly larger; the coarse aggregate slightly-segregated asphalt mixture (L) has stronger resistance to rutting deformation than the non-segregated asphalt mixture (N), which means that the skeleton-cohesive system formed by interaction of mineral aggregate particle contact friction and asphalt cohesive lubrication effect is the greatest in asphalt mixtures when coarse aggregate slightly segregates.
Sub-step 4.3, analyzing the relevance of the composite geometric indexes of the five asphalt mixtures and the water stability;
Referring to fig. 9, it can be seen that as the void fraction of the asphalt mixture increases, the number of flaking increases and decreases, and the number of flaking of the coarse aggregate slightly segregated asphalt mixture (L) is maximized;
With the increase of the void ratio of the asphalt mixture, the rutting depth is wholly in an ascending trend; this is because as the void fraction of the asphalt mixture increases, compactable spaces also exist between the mineral aggregates, which are more prone to rutting;
as the void fraction of the asphalt mixture increases, the spalling rate shows a less regular tendency of "M" type change, and the spalling rate of the coarse aggregate slightly segregated asphalt mixture (L) is minimized.
Referring to fig. 10, it can be seen that the void fraction VV of the asphalt mixture increases with the increase of the composite geometric index of the asphalt mixture, and the void fraction VV of the asphalt mixture has a better linear correlation with the composite texture index CI TX and the composite angular index CI GA, respectively.
In summary, the void ratio VV of the coarse aggregate mild-segregation asphalt mixture (L) is at a medium level, the moisture of the coarse aggregate mild-segregation asphalt mixture (L) entering the structure is less than that of the coarse aggregate moderate-segregation asphalt mixture (M) and the coarse aggregate severe-segregation asphalt mixture (H), and the coarse aggregate mild-segregation asphalt mixture (L) contains a certain amount of coarse aggregate which can form a stable skeleton structure, so that the peeling of the asphalt mixture under the coupling effect of water and load can be delayed, and the coarse aggregate mild-segregation asphalt mixture (L) has the best water stability.
Sub-step 4.4, analyzing the relevance of the composite geometric indexes of the five asphalt mixtures and the low-temperature crack resistance;
Referring to fig. 11, it can be seen that the tensile strength R T of the four asphalt mixtures, except for the fine aggregate segregation asphalt mixture (F), decreases with the increase of the degree of coarse aggregate segregation.
Referring to fig. 10, it can be seen that the void ratio VV, the composite texture index CI TX, and the composite angular index CI GA of the coarse aggregate medium segregation asphalt mixture (M) and the coarse aggregate heavy segregation asphalt mixture (H) are large; when the composite texture index CI TX and the composite angle index CI GA are larger, the more coarse aggregates of the asphalt mixture are, the more fine aggregates of the asphalt mixture are reduced, resulting in an increase in large voids of the asphalt mixture. Therefore, the internal cracks of the coarse aggregate medium segregation asphalt mixture (M) and the coarse aggregate heavy segregation asphalt mixture (H) are relatively fast in expansion speed;
The minimum composite texture index CI TX of the fine aggregate segregation asphalt mixture (F) indicates that the amount of the coarse aggregate of the fine aggregate segregation asphalt mixture (F) is the minimum, but the fine aggregate is the maximum, so that a large number of contact points appear in the fine aggregate segregation asphalt mixture (F), the transmission direction of stress is increased, and the stress dissipation is facilitated.
The coarse aggregate light segregation asphalt mixture (L) has more contact point decomposition stress, and the skeleton bonding strength is maximum and can resist external load, so that the coarse aggregate light segregation asphalt mixture (L) has the best low-temperature cracking resistance.
Comprehensive analysis shows that the low-temperature cracking resistance of the compact mixture is better than that of the skeleton void type, and the low-temperature cracking resistance of the coarse aggregate light segregation asphalt mixture (L) is the best. This is because microcracks are first formed in the upper and lower surfaces of the asphalt mixture test piece under the axial load in the indirect tensile test, and stress concentration phenomenon is generated at the tip of the microcracks. When more gaps are encountered in the stress transmission process, microcracks can rapidly expand; when the internal gaps of the mixture are fewer and the structure is compact, the stress transmission can meet continuous resistance, so that the crack propagation speed is slowed down.
Sub-step 4.5, according to the analysis, the particle shape mainly influences the rotation rate of the particles, plays an auxiliary role on the edges and corners of the particles and the grain surface texture, and has little influence on the macroscopic performance of the asphalt mixture; the embedding of the edges and corners of the particles and the friction of the textures on the surfaces of the particles determine the contact state among the particles, so that the macroscopic performance of the asphalt mixture is greatly influenced; thus, an aggregate segregation pre-judgment model is established by adopting the composite texture index CI TX and the composite edge index CI GA.
And 5, respectively carrying out normalization processing on the composite texture index CI TX and the composite edge index CI GA by adopting a maximum value calculation method, and respectively establishing models as shown in the formulas (1) and (2).
Maximum value of composite texture index of asphalt mixture according to the gradation range commonly used for upper and middle layers recommended in Highway asphalt pavement construction technical SpecificationMaximum value of composite angular index of asphalt mixtureTaking a composite geometric index of SMA-20L; maximum value of composite texture index of asphalt mixtureThe value of 2447.62397312175 is the maximum value of the composite edge index of the asphalt mixture40008.2752815776 Was taken.
The effects of the present invention are further described in conjunction with the following experiments:
Test step 1: selecting raw materials and mineral aggregate grading.
The test adopts limestone in a certain place of Shaanxi, main technical indexes of coarse aggregates and fine aggregates are measured according to the specification of the highway engineering aggregate test procedure (JTG E42-2005), and the corresponding technical indexes of materials are recorded through the test, as shown in table 2.
TABLE 2 main technical index of coarse and fine aggregates
The test selects 4 gradations, and various gradations are shown in table 2.
TABLE 3 mesh passing rate of different gradations (%)
Test step 2: and calculating aggregate composite texture segregation tendency indexes STI TX and aggregate composite edge segregation tendency indexes STI GA of the asphalt mixtures under 4 gradations, and pre-judging aggregate segregation tendency of the asphalt mixtures.
The aggregate composite texture segregation tendency index STI TX and the aggregate composite angular segregation tendency index STI GA of the 4 graded asphalt mixtures were calculated as shown in table 4.
TABLE 4 segregation tendency index for different grades of mineral spirits
| Grading type | S1 | S2 | S3 | S4 |
| STITX | 0.153323 | 0.180296 | 0.16162 | 0.144464 |
| STIGA | 0.514258 | 0.600224 | 0.570886 | 0.564634 |
Comparing the segregation trend index of 4 graded asphalt mixtures with the asphalt mixture aggregate segregation evaluation criteria table, it is obtained that all of the 4 graded asphalt mixtures have a fine aggregate segregation trend, but the fine aggregate segregation trend of the S 2 graded asphalt mixtures is relatively small.
While the invention has been described in detail in this specification with reference to the general description and the specific embodiments thereof, it will be apparent to one skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.
Claims (1)
1. The asphalt mixture aggregate segregation pre-judging method is characterized by comprising the following steps of:
step S1, an aggregate segregation pre-judging model of the asphalt mixture is established, wherein the aggregate segregation pre-judging model is shown in a formula (1) and a formula (2);
in the formula (1), STI TX is the aggregate composite texture segregation trend index of the asphalt mixture, CI TX is the composite texture index of the asphalt mixture, and CI TXmax is the maximum value of the composite texture index of the asphalt mixture;
In the formula (2), STI GA is the aggregate composite angular segregation tendency index of the asphalt mixture, CI GA is the composite angular index of the asphalt mixture, and CI GAmax is the maximum value of the composite angular index of the asphalt mixture;
s2, establishing an asphalt mixture aggregate segregation evaluation standard;
When the aggregate composite texture segregation tendency index STI TX of the asphalt mixture has values of 0 to 0.2, 0.2 to 0.25, 0.25 to 0.3, 0.3 to 0.35 and 0.35 to 1, the aggregate segregation degree of the asphalt mixture corresponds to fine aggregate segregation, no segregation, coarse aggregate mild segregation, coarse aggregate moderate segregation and coarse aggregate severe segregation respectively; when the aggregate compound angular segregation tendency index STI GA of the asphalt mixture has values of 0 to 0.6, 0.6 to 0.7, 0.7 to 0.8, 0.8 to 0.9 and 0.9 to 1, the aggregate segregation degree of the asphalt mixture corresponds to fine aggregate segregation, no segregation, coarse aggregate mild segregation, coarse aggregate moderate segregation and coarse aggregate severe segregation respectively;
Step S3, calculating aggregate composite texture segregation trend index STI TX and aggregate composite edge segregation trend index STI GA of the asphalt mixture to be pre-judged, comparing with an asphalt mixture aggregate segregation evaluation standard, and pre-judging the aggregate segregation degree of the asphalt mixture;
The composite texture index CI TX of the asphalt mixture in the step S1 is calculated by a method shown in a formula (4);
In the formula (4):
a i is the percentage of screen residue of the ith grade aggregate in the grading design;
n is the particle size of all aggregates in the grading design;
m is the grain size grade number of coarse aggregate used in grading design;
g i is the volumetric relative density of the i-th grade aggregate;
d i is the average particle size of the i-th grade aggregate, Wherein P i+1 is the mesh size of the i+1st set;
V wi is the weighted volume of aggregate particle shape, V Wi＝Vci×SPi+Vsi×(1-SPi), wherein the cube volume: Sphere volume:
SA wi is the weighted surface area of the aggregate particle shape, SA Wi＝SAci×SPi+SAsi×(1-SPi), where the cube surface area: Sphere surface area:
TX i is a surface texture index;
GA i is the angular gradient of the i-th grade aggregate;
The calculating method of the composite edge index CI GA of the asphalt mixture in the step S1 is shown in the formula (5);
In formula (5):
a i is the percentage of screen residue of the ith grade aggregate in the grading design;
n is the particle size of all aggregates in the grading design;
m is the grain size grade number of coarse aggregate used in grading design;
g i is the volumetric relative density of the i-th grade aggregate;
d i is the average particle size of the i-th grade aggregate, Wherein P i+1 is the mesh size of the i+1st set;
V wi is the weighted volume of aggregate particle shape, V Wi＝Vci×SPi+Vsi×(1-SPi), wherein the cube volume: Sphere volume:
GA i is the angular gradient of the i-th grade aggregate;
M is the total mass of mineral aggregates;
The maximum value of the composite texture index of the asphalt mixture in the step S1 Maximum value of composite angular index of asphalt mixtureSpecifically, the maximum value of the composite texture index of the asphalt mixtureHas a value of 2447.62397312175, the maximum value of the composite angular index of the asphalt mixtureHas a value of 40008.2752815776.
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