CN106018463B - A kind of evaluation method of pitch crack resistance at low-temperature - Google Patents
A kind of evaluation method of pitch crack resistance at low-temperature Download PDFInfo
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- CN106018463B CN106018463B CN201610377177.2A CN201610377177A CN106018463B CN 106018463 B CN106018463 B CN 106018463B CN 201610377177 A CN201610377177 A CN 201610377177A CN 106018463 B CN106018463 B CN 106018463B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/14—Investigating or analyzing materials by the use of thermal means by using distillation, extraction, sublimation, condensation, freezing, or crystallisation
Abstract
The invention discloses a kind of evaluation method of pitch crack resistance at low-temperature, comprise the following steps：Taking or preparing has an annular groove in the middle of base and not swollen annulus, base, not swollen annulus is closely surrounded on the internal ring wall of annular groove, and base is provided with a cynapse on the external annulus of annular groove, and cynapse is the cylindrical cynapse being horizontally placed on the external annulus of annular groove；Heated asphalt, is poured into the annular space between not swollen annulus and annular groove external annulus, and cooling shaping obtains pitch annulus；Cooling, until pitch annulus is broken, detects and records the instantaneous strain value of temperature value and not swollen annulus in the position of correspondence cynapse.Corresponding maximum breaking strain when the method is broken by approximate simulation road surface, sets up with the actual low-temperature condition of paving mix and associates；Selective cleavage can be realized, targetedly breaking part intensity level can be measured；The ring crack temperature measured using the method and TSRST breaking temperatures have a preferable correlation, and the method accuracy and reproducible.
Description
Technical field
The invention belongs to asphalt performance assessment technique field, more particularly to a kind of evaluation side of pitch crack resistance at low-temperature
Method.
Background technology
The cracking of bituminous paving is domestic and international road circle question of common concern, and its harm is moisture is immersed along crack
Inside pavement structure, so that sub-surface and roadbed feel like jelly, pavement structure depression of bearing force is produced under Driving Loading
Purt mud, wash away, boundary layer occur it is local comes to nothing, ultimately result in road surface and check crack and pit occur, severely impact the traveling of vehicle
Quality, greatly reduces the service life on road surface.
The crack of bituminous paving includes load Crack and non-loaded deformation.In China, some overload in the crack produced by load
Serious high-grade highway runway is often met, now many to control fatigue rupture as core content.And another kind of crack, i.e., it is non-
Reflection crack caused by the low-temperature shrink crack of load type and semi-rigid type base but generally existing, has caused suitable pass
Note, it is well known that both cracks are closely related with the cracking resistance of pitch and asphalt.In recent years, carry out both at home and abroad
More research work, wherein, many researchs it is main with asphalt surface course cold cracking be main goal in research.
Since taking the lead in carrying out systematic investigation and study to the cold shrinkage crack of asphalt surface course from Canada's sixties in 20th century, road surface
Cracking resistance and the important research content that material at low temperature performance indications are always international road educational circles, lead in research over nearly 20 years with application
Domain is even more and achieves breakthrough progress.Obtained common recognition is：Control pitch and the cryogenic property of asphalt, set up phase
Cryogenic property index and feasible value are closed, is the key measure of asphalt surface course cold cracking design.And the anti-low-temperature cracking of bituminous paving
Performance depends primarily on the cryogenic tensile characteristic of asphalt binder, and the performance of asphalt binder plays especially important effect, phase
Close document to show, its contribution rate is to 90%, therefore research to asphalt surface course cold cracking should be with pitch cryogenic property index
Control based on.
By the analysis to domestic and international pitch low temperature evaluation index, current Conventional cryogenic index is in mechanical mechanism, experiment
As a result discrimination and certain deficiency is still suffered from the aspect such as the road surface degree of correlation, many aspects are unreasonable；SHRP indexs can be compared with
The cryogenic property of good evaluation matrix pitch, and evaluation well can not be made to modified pitch, and SHRP indexs are used
Creep properties is classified, it is believed that croop property can substitute destructive characteristics, but research shows the phase of croop property and destructive characteristics
Closing property is not fine.At this stage, currently existing low temperature index can not make comparisons clear and definite table to the cryogenic property of pitch
Levy, one more easy intuitively index of necessary proposition is evaluated asphalt performance.
The content of the invention
The technical problems to be solved by the invention are to provide a kind of evaluation method of pitch crack resistance at low-temperature.
The technical solution used in the present invention is：
A kind of evaluation method of pitch crack resistance at low-temperature, comprises the following steps：
S1：Base and not swollen annulus are taken or prepared, there is an annular groove in the middle of the base, the not swollen annulus closely covers
On the internal ring wall of the annular groove, the base is provided with a cynapse on the external annulus of the annular groove, and the cynapse is water
The flat cylindrical cynapse being arranged on the external annulus of the annular groove；
S2：Heated asphalt, is poured into the annular space between not swollen annulus and the annular groove external annulus, cooling
Shaping, obtains pitch annulus；
S3：Cooling, until the pitch annulus is broken, detects and records temperature value and not swollen annulus in the position of correspondence cynapse
The instantaneous strain value put.
In some specific embodiments, be additionally included between the S1 and S2 the not swollen annulus lateral wall and
The step of madial wall uniform application lubricant of the annular groove.
In some specific embodiments, the S3's concretely comprises the following steps：It is not swollen described in relative with the cynapse
Strain transducer is set on the madial wall of annulus, temperature sensor is set on base, by base, not swollen annulus is together with the drip
Blue or green annulus is put into heat sink together, preheating, then controls heat sink to lower the temperature with steady rate, until the pitch annulus
Fracture, detects and records the instantaneous strain value of temperature value and not swollen annulus in the position of correspondence cynapse.
In further preferred embodiment, S4 is also included after the S3：Draw the instantaneous strain value that obtains of detection with
Temperature variation curve, when instantaneous strain value is jumped, corresponding temperature value is the temperature during fracture of asphalt material, i.e. ring
Split temperature.
In some specific embodiments, the diameter of the cylindrical cynapse can determine according to public formula (I)：
In formula, S represents the diameter of the cylindrical cynapse, and h represents the height of the cylindrical cynapse；R1Described in representing not
The outer shroud radius of swollen annulus；The H represents the height of the pitch annulus；D determines according to public formula (II)：
In formula, αDripIt is the linear expansion coefficient of pitch；αNECRIt is the linear expansion coefficient of not swollen annulus；Δ T is cooling extent；R1
It is the outer shroud radius of the not swollen annulus；R2It is the outer shroud radius of the pitch annulus；In formula, parameter εAIt is true by public formula (III)
It is fixed：
εA=(αDrip+M·αCollection) Δ T ﹣ M εCollection (III)
In formula, Δ T is cooling extent；αDripIt is the linear expansion coefficient of pitch；M is the length ratio for gathering materials one-dimensional with pitch；αCollection
It is the linear expansion coefficient for gathering materials；εCollectionIt is the strain gathered materials.
In some specific embodiments, linear expansion coefficient≤5 × 10 of the not swollen annulus-6mm/mm/℃。
In some specific embodiments, the material of the not swollen annulus is quartz glass, invar alloy, ceramics and steel
In any one.
In some specific embodiments, the material of the not swollen annulus is quartz glass.
In some specific embodiments, the material of the base is any one in steel, iron, aluminium.
In some specific embodiments, the cooling rate scope in the S3 is 1~30 DEG C/h.
The beneficial effects of the invention are as follows：The invention provides a kind of evaluation method of pitch crack resistance at low-temperature, by system
Standby base and not swollen annulus, have an annular groove in the middle of the base, the not swollen annulus closely surrounds the interior of the annular groove
On ring wall, the base is provided with a cynapse on the external annulus of the annular groove, and the cynapse is to be horizontally placed on the annular
Cylindrical cynapse on the external annulus of groove, heated asphalt is poured into described between not swollen annulus and the annular groove outer shroud
Annular space, cooling shaping obtains pitch annulus, lowers the temperature, until the pitch annulus is broken, detect and record temperature value and
Instantaneous strain value of the not swollen annulus in the position of correspondence cynapse., by controlling the continuous decrease of temperature, pitch annulus is or not this method
Disconnected cooling is shunk, very small with temperature shrinkage amount without swollen annulus, is kept approximately constant, so that pitch ring specimen inside produces
Temperature stress, and constantly increase with continued down, until when temperature is down to certain value, pitch annulus fracture, due in the ring
Cynapse is provided with the external annulus of shape groove, makes pitch annulus cross-sectional area at cynapse minimum, stress maximum suffered by cynapse,
So the point that can be at low temperature broken pitch annulus is controlled at cynapse, selective cleavage is realized；Due to pitch annulus and not
The interaction force of swollen annulus is equal, so strain value of the pitch annulus at cynapse and not swollen annulus are in cynapse correspondence position
Strain value is equal, so detected instantaneous strain value is instantaneous strain value of the pitch annulus at cynapse, record is instantaneous
Strain value and temperature value, when instantaneous strain value is undergone mutation, now pitch annulus fracture, corresponding temperature value is ring crack temperature
TFracThe temperature of pitch annulus while being broken (), corresponding instantaneous strain value is ring crack strain value, by stress-strain relation, i.e.,
The fracture strength σ of pitch can be calculatedFrac.The evaluation of pitch crack resistance at low-temperature is carried out using this method, with following excellent
Point：1) can approximate simulation road surface corresponding maximum breaking strain when being broken, associated with the foundation of the actual low-temperature condition in road surface；2) may be used
Selective cleavage is realized, the cylinder cynapse point on pitch annulus, i.e., in stress maximum suffered by pitch, controlled fracturing blasting is sent out herein
Raw (this puts corresponding with the fracture of actual road surface), and routinely freeze disconnected experiment, test it is previous as indefinite breakaway poing position, this is not only
The effective control to testing is improve, the measurement to breaking strength values herein is also targetedly facilitated；3) for different blended
The type and proportion of composing of material are closed, the size of joint base can simulate calculating, and the cross-sectional area for adjusting cylindric cynapse is (logical
Cross and change different cylinder synapse types), targetedly can carry out cryogenic property test by road pavement different type compound,
To accomplish to be more nearly with road surface actual state, this point any pitch crack resistance at low-temperature evaluation at present cannot all be accomplished；4)
Obtain out ring crack temperature TFracWhile, also measure corresponding fracture strength σFrac；5) commented using the pitch cryogenic property
Valency structure monitoring to ring crack temperature and TSRST breaking temperatures there is preferable correlation, and evaluation method of the present invention is accurate
True property and reproducible.
Brief description of the drawings
Fig. 1 is the top view of base；
Fig. 2 is Section A-A sectional view in Fig. 1；
Fig. 3 is the pictorial diagram of unlike material and various sizes of not swollen annulus；
Fig. 4 is the pictorial diagram of various sizes of cynapse；
Fig. 5 is that pitch ring crack freezes disconnected disc structure top view；
Fig. 6 is section B-B sectional view in Fig. 5；
Fig. 7 is pitch low temperature ring crack test instrument structural representation.
Fig. 8 is bituminous paving model schematic；
Fig. 9 is pavement asphalt mixture check model figure；
Figure 10 is pavement cracking schematic illustration of strain；
Figure 11 is pitch annulus and not swollen annulus force balance schematic diagram；
Figure 12 is pitch annulus and the not swollen front and rear strain variation schematic diagram of annulus cooling；
Figure 13 is nonuniform section pitch annulus equivalent schematic；
Figure 14 is the correlation analysis figure of the not swollen annulus gained ring crack temperature of quartz glass and TSRST breaking temperatures；
Figure 15 is the correlation analysis figure of the not swollen annulus gained ring crack temperature of invar alloy and TSRST breaking temperatures；
Figure 16 is the correlation analysis figure of the not swollen annulus gained ring crack temperature of ceramics and TSRST breaking temperatures；
Figure 17 is strained for a kind of not swollen annulus material to vary with temperature curve；
Figure 18 is different pitches material correspondence rate of temperature fall and ring crack temperature relation figure.
Description of reference numerals：
1- bases；2- annular grooves；3- internal ring walls；4- external annulus；5- cynapses；6- is not swollen annulus；7- pitch annulus；8- is circular
Depression；9- strain transducers；10- temperature sensors；11- closes accommodation space；12- temperature acquisition processors；13- strain acquirements
Processor；14- liquid nitrogen cooling systems；15- material height temperature test instruments.
Specific embodiment
Freeze disconnected disc structure and a pitch low temperature ring crack test instrument the present invention relates to a ring crack.A kind of pitch ring crack is frozen
Disconnected disc structure, including base 1 and not swollen annulus 6.Reference picture 1, Fig. 1 is the top view of base, has one in the middle of the base 1
Annular groove 2, the base 1 is provided with a cynapse 5, reference picture 2 on the external annulus 4 of the annular groove 2, and Fig. 2 is A-A sections in Fig. 1
Face sectional view, the cynapse 5 is the cylindrical cynapse being horizontally placed on the external annulus 4 of the annular groove 2.The base 1
Centre be provided with a circular depressed 8, the circular depressed 8 is concentric with the annular groove 2, and the radius of the circular depressed 8 is equal to
The radius of internal ring wall 3 of the annular groove 2, the depth of the depth less than the annular groove 2 of the circular depressed 8.The not swollen circle
The material of ring 6 need to be varied with temperature and Volume Changes very little, linear expansion coefficient≤5 × 10 of the not swollen annulus 6-6mm/mm/
℃.In a preferred embodiment, the material of the not swollen annulus 6 is quartz glass.The material of the base 1 is in steel, iron, aluminium
Any one.
Reference picture 3, Fig. 3 a are respectively use quartz glass, ceramics, invar alloy, the different materials of four kinds of ordinary steel from left to right
The not swollen annulus that matter makes, Fig. 3 b are the not swollen annulus of various sizes of quartz glass material.
Reference picture 4, Fig. 4 is the pictorial diagram of various sizes of cynapse, and the cynapse 5 includes first end and the second end, described
First end is cylindrical, and the size of the cylinder of the first end can be adjusted, pointedly to simulate road pavement inhomogeneity
Type compound carries out cryogenic property test, can accomplish to be more nearly with road surface actual state, and second end is embedded in institute
State in the external annulus 4 of annular groove 2.
Reference picture 5, the not swollen annulus 6 is closely surrounded on the internal ring wall 3 of the annular groove 2, outside the not swollen annulus 6
An annular accommodation space is formed between wall and the annular groove 2, the annular accommodation space is used to place pitch, in test process
In, first pitch is heated, the annular accommodation space is then poured into, cooling shaping obtains pitch annulus 7, the temperature
Acquisition Instrument includes temperature sensor 10 and the two parts of temperature acquisition processor 12, and it is recessed that the temperature sensor 10 is placed in the circle
8 center is fallen into, the temperature of the base 1 is the temperature for being regarded as the pitch annulus 7, and the temperature sensor 10 is used for
Test ring crack freezes the temperature of pitch ring in disconnected disk.The height of the cylindrical cynapse is equal to the outer shroud 4 half of the annular groove 2
The difference of the outer shroud radius of footpath and the not swollen annulus 6.The strain acquirement instrument includes strain transducer 9 and is processed with strain acquirement
The two parts of device 13, the strain transducer 9 is located on the inwall of the relative described not swollen annulus 6 of the cynapse 5, due to the bottom
There is the circular depressed 8 in seat 1, so facilitating the setting of the strain transducer 9.
Reference picture 6, the bottom of the annular groove 2 is horizontal.The width of the not swollen annulus 6 is equal to the annular groove 2
Depth.
Reference picture 7, freezes present invention also offers a kind of pitch low temperature ring crack test instrument, including pitch ring crack as described above
Disconnected disc structure, the pitch low temperature ring crack test instrument also includes heat sink, temperature sensor and strain acquirement instrument, the drop
Warm device has a closing accommodation space that can accommodate the pitch cryogenic property evaluation structure, the temperature sensor bag
The temperature sensor 10 and temperature acquisition processor 12 being connected are included, the temperature sensor 10 freezes disconnected located at the pitch ring crack
On the base 1 of disc structure, the strain acquirement instrument includes the strain transducer 9 and strain acquirement processor 13 that are connected, should
Become sensor 9 to be located on the inwall relative with the cynapse 5 of not swollen annulus 6.In the present embodiment, pitch low temperature ring crack experiment
Instrument includes that pitch ring crack freezes disconnected disc structure, material height temperature test instrument 15, temperature sensor (by temperature sensor 10 and temperature
The two parts of Acquisition Processor 12 constitute, both by data wire connect), strain acquirement instrument (strain transducer 9 and and strain acquirement
The two parts of processor 13 constitute, by data wire connect), the part of liquid nitrogen cooling system 14 5 constitute.Material height temperature test instrument
15 are provided with single-stage cooling compression set, and material height temperature test instrument 15 has closing accommodation space 11.Liquid nitrogen cooling system
14 Main Function is on the basis of the single stage compress heat sink of material height temperature test instrument 15, to take liquid nitrogen cooling measure
Further cooling reinforcing is carried out to experiment.
The invention provides a kind of evaluation method of pitch crack resistance at low-temperature, comprise the following steps：S1：Take or prepare bottom
Seat 1 and not swollen annulus 2 (No Expansion Circle Ring, abbreviation NECR), the base 1 and the not swollen knot of annulus 2
Structure freezes base 1 and the not swollen annulus 2 described in disconnected disc structure such as above-mentioned ring crack, and the not swollen annulus 2 is little with temperature
Change and Volume Changes occur, the shape of the base 1 can be arbitrary shape, such as rectangle, circle, ellipse, preferred
Embodiment described in base 1 be shaped as circle, there is an annular groove 2 in the middle of the base 1, the not swollen annulus 6 is nested
On the internal ring wall 3 of the annular groove 2, the base 1 is provided with a cynapse 5, the cynapse 5 on the external annulus 4 of the annular groove 2
To be horizontally placed on the cylindrical cynapse on the external annulus 4 of the annular groove 2；S2：The not swollen annulus 6 lateral wall and
The madial wall uniform application lubricant of the annular groove 2, so that pitch will not adhere to not swollen annulus in temperature-fall period, it is to avoid
Abnormal reading strain is produced, test data is influenceed；S3：Heated asphalt, is poured into the not swollen annulus 6 and the annular groove 2
External annulus 4 between annular space, cooling shaping obtains pitch annulus 7；S4：It is not swollen described in relative with the cynapse 5
Strain transducer 9 is set on the madial wall of annulus 6, temperature sensor 10 is set on base 1, by base 1, not swollen annulus 6 connects
It is put into together in the closing accommodation space 11 of material height temperature test instrument 15 with the pitch annulus 7,0 DEG C of preheating 30min, then
Control heat sink is lowered the temperature with steady rate, and rate of temperature fall scope is 1-30 DEG C/h, until the pitch annulus 7 is broken,
Detect and record the instantaneous strain value of temperature value and not swollen annulus 6 in the position of correspondence cynapse 5；S5：Draw the wink that detection is obtained
When strain value vary with temperature curve, when instantaneous strain value is jumped, corresponding strain value be pitch be broken when not swollen circle
Ring cynapse correspondence position strain value, due to the mutual extruding that pitch annulus and not swollen annulus are produced in contraction process of lowering the temperature
It is active force and reaction force, i.e. FNot swollen annulus=FDrip, the parameter ε obtained by experimentStrain jump valueWith ess-strain formula F=ε
E·ASectional area, F can be obtainedNot swollen annulus, obtain final product directed force F suffered by pitch annulusDrip.Then F is passed throughDrip=σDrip·ADrip, obtain asphalt material
Ring crack intensity σDrip, i.e. σFrac.And the temperature value corresponding to being broken at this moment is the temperature when pitch annulus 7 is broken,
That is ring crack temperature TFrac.In a preferred embodiment, cooling rate can be 10 DEG C/h.The linear expansion coefficient of the not swollen annulus 2
≤5×10-6mm/mm/℃.The material of the not swollen annulus 2 is any one in quartz glass, invar alloy, ceramics and steel.Institute
It is any one in steel, iron, aluminium to state the material of base.
Principle Analysis：
The mechanism to ring crack experiment is analyzed below.In process of the test, annular freezes what disconnected disk was tested as ring crack
Important composition part, its internal composition is as shown in Figure 5.Inner ring is not swollen annulus (No Expansion Circle Ring, abbreviation
NECR, generally linear contractive quotiety very little, (0~5) × 10-6Mm/mm/ DEG C), outer shroud is that (linear contractive quotiety α is typically big for pitch ring
In 200 × 10-6Mm/mm/ DEG C), two kinds of material α differ larger, about two orders of magnitude.In experiment temperature-fall period is carried out,
Pitch produces contraction with not swollen annulus temperature influence, because of the length reduction amount that pitch ring is produced by temperature change in the unit interval
It is bigger than not swollen annulus, asphalt material is directly generated phase in annulus tangential direction and vertical tangent lines direction with not swollen annulus
Mutual squeezing action power, with the continuous decline of temperature, asphalt material constantly shrinks in the presence of stress, when (the drip of pitch ring
Green material is in itself) institute's tension stress is when reaching the tensile strength of its fracture, pitch ring fracture (therefore claim ring crack experiment).
First, road surface virtual condition analysis
Elasticity and strength failure of the design of the test method based on material are theoretical.
Reference picture 8, bituminous paving actual conditions take one of them as shown in figure 8, the figure is bituminous paving model schematic
Fritter asphalt is analyzed, road surface Asphalt Mixture check model figure such as Fig. 9, conventional pavement asphalt mixture by
Pitch, gather materials and space composition, gather materials about of the total volume 83~85%, pitch of the total volume 10~12%, voidage
Account for 4~5%.
It is assumed that gather materials accounting for the 85% of volume, pitch of the total volume 15%, both volume ratios are 5.7:1, research first wouldn't
Consider the volume in space, the cube grid of upper figuredGather materials=0.9473, dPitch=1-dGather materials=0.0527, gather materials with
The one-dimensional length ratio of pitch is 18:1, proportionality coefficient is represented with M, i.e. M=18.
As shown in Figure 10, Figure 10 is pavement cracking schematic illustration of strain, and under the conditions of microthermal climate, bituminous paving just starts
Low-temperature shrink, and due to the effect of contraction of road surface longitudinal direction, the length change on road surface is limited, add road surface cryogenic conditions lower aprons
It is elastomer, road surface is just occurred in that elastic shrinkage deforms, produced temperature stress is balanced with this.
Now, still uncracked road surface meets the strain stress relation formula as shown in formula (1.1)：
(αDrip+M·αCollection) Δ T=εDrip (road surface)+M·εCollection (1.1)
2nd, the lab simulation of evaluation method of the present invention and mechanical analysis
Reference picture 11, Figure 11 is pitch annulus and not swollen annulus force balance schematic diagram, is lowered the temperature laboratory test is carried out
Cheng Zhong, pitch annulus produces contraction with not swollen annulus temperature influence, because pitch annulus is produced by temperature change in the unit interval
Length reduction amount it is bigger than not swollen annulus, make asphalt material with not swollen annulus directly in annulus tangential direction and vertical tangent lines side
To mutual squeezing action power is generated, i.e., pitch annulus is always maintained at the equilibrium-like of stress during this before being not yet broken
State, meets the equilibrium relation as shown in formula (2.1), (2.2)：
PDrip=PNECR (2.1)
P ＇Drip=PN＇ECR (2.2)
In formula, PDripThe interaction force of tangential direction suffered by pitch annulus；PNECRThe tangential direction suffered by not swollen annulus
Interaction force；P ＇DripInteraction force, P suffered by pitch annulus perpendicular to tangential directionN＇ECRSuffered by not swollen annulus
Perpendicular to the interaction force of tangential direction.
As shown in Figure 11, with not swollen annulus in contraction process, pitch annulus contracted length is in the unit interval for pitch annulus
Not swollen annulus is greater than, and to keep poised state, it is necessary to lean on pitch with the elastic strain of not swollen annulus to support.Such as Fig. 7 institutes
Show, Fig. 7 is pitch annulus and the not swollen front and rear strain variation schematic diagram of annulus cooling, if the pitch annulus is uniform cross-section,
Pitch annulus is met with the relational expression as shown in formula (2.3) with the strain of not swollen annulus：
(αDrip﹣ αNECR) Δ T=εDrip (interior)+εNECR (2.3)
In formula, αDripIt is the linear expansion coefficient of pitch；αNECRIt is the linear expansion coefficient of not swollen annulus；Δ T is cooling extent；
εDrip (interior)It is the strain of pitch in experiment；εNECRIt is the strain of not swollen annulus.
Indoor ring crack experiment is carried out into simulated roadway freezing crack situation, σ is selectedDrip (interior)=σDrip (road surface)Or εDrip (interior)=
εDrip (road surface), wherein, σDrip (interior)The stress suffered by pitch in experiment, σDrip (road surface)It is stress, ε suffered by pitch in actual road surfaceDrip (interior)It is examination
Test the strain of middle pitch, εDrip (road surface)It is the strain of pitch in actual road surface, i.e., equivalent to by the ring crack test instrument and actual road surface one
Rise and be placed in same cooling environment, the fracture for planting pitch together is farthest consistent with pavement behavior.
The present invention is provided with a cynapse on the external annulus of the annular groove, and the cynapse is to be horizontally placed on the annular groove
External annulus on cylindrical cynapse, by setting this cynapse so that reduced cross-sectional area of the pitch annulus at cynapse,
Because pressure (i.e. with the not swollen direct interaction force of annulus) keeps constant on pitch annulus, so the pitch at this cynapse
Suffered ess-strain is maximum, is fixed on pitch annulus and is broken herein, realizes selective cleavage, disconnected such that it is able to pinpoint detection
Split place's strain value.
The present invention can also be by adjusting the size of cylinder cynapse, as shown in figure 4, so that suffered by this pitch annulus inside
Consistent approximate with the breaking strain holding of the actual compound in road surface of breaking strain.Pitch annulus cross-sectional area at cynapse is become
Small to be equivalent to nonuniform section as shown in fig. 13 that, pitch annulus cross-sectional area is minimum during position at cynapse is equivalent into Figure 13
Place, i.e., at AD line segments.Selection nonuniform section pitch annulus on A points (strain maximum of points) as research object, make its with
Pavement strain opening relationships εA=εDrip (road surface), wherein εAIt is the strain of A point pitches, εDrip (road surface)It is the strain of pitch in actual road surface.
Then under the conditions of nonuniform section, formula (2.3) can be converted into formula (2.4)
(αDrip﹣ αNECR) Δ T=εDrip (nonuniform section)+εNECR (2.4)
Wherein, εDrip (nonuniform section)Dependent variable produced by nonuniform section pitch annulus entirety.
Assuming that the cross-sectional length d in Figure 13 is being continually changing, R1It is the outer shroud radius of the not swollen annulus；R2It is the drip
The outer shroud radius of blue or green annulus；Angle change value is θ.
Because the material modulus of not swollen annulus selection are very big, the ε of generationNECRVery little, first assumes εNECR≈0。
As shown in figure 13, so it is considered that under identical cooling situation, constantly adjustment pitch toroid size is to make
εAMeet εA=εDrip (road surface)While, whole pitch annulus keeps constant because of the overall strain amount produced by temperature change, i.e.,
In formula：ε1ForThe internal strain of pitch annulus in angle；
ε2ForThe internal strain of pitch annulus in angle；
And
Then
In formula：R1It is the outer shroud radius of the not swollen annulus, mm；R2It is the outer shroud radius of the pitch annulus, mm；αDripFor
The linear expansion coefficient of pitch；αNECRIt is the linear expansion coefficient of not swollen annulus, mm/mm/ DEG C；αCollectionIt is the linear expansion coefficient for gathering materials；ΔT
It is cooling extent, DEG C；M is the length ratio for gathering materials one-dimensional with pitch；It is known.
By the calculating of formula (2.7), formula (2.6) is simplified, formula (2.6) can be converted into formula (2.8),
Wherein,
Have already mentioned above, while pitch annulus is selectively broken at A, also make the chi by adjusting cylinder cynapse
It is very little so that this pitch annulus inside suffered by breaking strain (take point εA) with the breaking strain ε of the actual compound in road surfaceDrip (road surface)(formula
(1.1) shown in) keep approximate consistent, i.e., as shown in following formula (2.9).
εA=εDrip (road surface)=(αDrip+M·αCollection) Δ T ﹣ M εCollection (2.9)
Calculated by simultaneous formula (2.8), formula (2.9), you can obtain public formula (II)：
In formula, αDripIt is the linear expansion coefficient of pitch；αNECRIt is the linear expansion coefficient of not swollen annulus；Δ T is cooling extent；R1
It is the outer shroud radius of the not swollen annulus；R2It is the outer shroud radius of the pitch annulus；In formula, parameter εAIt is true by public formula (III)
It is fixed：
εA=(αDrip+M·αCollection) Δ T ﹣ M εCollection (III)
In formula, Δ T is cooling extent；αDripIt is the linear expansion coefficient of pitch；M is the length ratio for gathering materials one-dimensional with pitch；αCollection
It is the linear expansion coefficient for gathering materials；εCollectionIt is the strain gathered materials.D can be calculated by public formula (II) and public formula (III).To sum up, use
Evaluation method of the present invention can be directed to the type and proportion of composing of different compounds, and the size of joint base can simulate meter
Calculate, adjust the cross-sectional area of cylindric cynapse, targetedly can carry out cryogenic property by road pavement different type compound
Test, to accomplish to be more nearly with road surface actual state, this point any pitch crack resistance at low-temperature evaluation at present cannot all be done
Arrive.
After obtaining length d, you can the pitch annulus cross-sectional area corresponding to Figure 13 middle conductors AD is obtained, then according to this face
Product determines the size of cylindric cynapse used, and the diameter S of cylindrical cynapse can be obtained according to formula (I),
In formula, h represents the height of the cylindrical cynapse；R1The outer shroud radius of not swollen annulus described in representing；The H is represented
The height of the pitch annulus.In a preferred embodiment, the height h of the cylindrical cynapse is equal to the outer of the annular groove
The difference of the outer shroud radius of ring radius and the not swollen annulus.
Cynapse is arranged on the external annulus of the annular groove of the base and is tested, pitch annulus is obtained in ring crack with this
Ring crack temperature T corresponding during destructionFracWith ring crack intensity σFrac。
Die trial size R is used herein1=30mm, R2=36mm, linear contractive quotiety is calculated assumes αDrip=200 × 10-6, αCollection=
5×10-6, αNECR=0.5 × 10-6, by simultaneous formula (2.8), (2.9), d=32.2mm can be tried to achieve.It is true finally by calculating
Fixed cylindric cynapse size is Φ 8mm × 6mm (h).
Loading process to actual road surface makees a hypothesis：PDrip=PCollection, the interaction force of asphalt and aggregate is equal, and the ring
Split experiment and also meet PDrip=PNECR, i.e. the interaction force of pitch and not swollen annulus is equal, then formula (2.10) and (2.11)：
σDrip·ADrip=σCollection·ACollection=σNECR·ANECR (2.10)
That is εDrip·EDrip·ADrip=εCollection·ECollection·ACollection=εNECR·ENECR·ANECR (2.11)
In formula, EDripIt is the elastic modelling quantity of pitch；ECollectionIt is the elastic modelling quantity for gathering materials；ENECRIt is the elastic modelling quantity of not swollen annulus.
Assuming that the elastic strain of generation of gathering materials on road surface is equal with the microstrain that not swollen annulus is produced, i.e. εNECR=M
εCollection。
By the simultaneous equation, A is obtainedNECR, i.e., the cross-sectional area of not swollen annulus, correspondence annulus highly obtain experiment institute
The thickness of corresponding not swollen annulus.
Analyzed more than, the not swollen annulus ring thickness size for finally determining the annular die trial is 2mm, the chi of cylindric cynapse
Very little is Φ 8mm × 6mm (h).
In sum, the strain at the temperature change value and cynapse by detecting temperature-fall period pitch of the invention, finally may be used
Ring crack strain and the ring crack temperature of pitch annulus are obtained, and the ring crack strains corresponding maximum fracture when can be broken with simulated roadway
Strain, can also obtain the fracture strength of corresponding pitch according to ring crack strain, be set up with the actual low-temperature condition of paving mix
Association, realizes the evaluation of the crack resistance at low-temperature of paving mix；For different mix type and proportion of composing, can adjust
The axial cross section area of whole cynapse is tested with the cryogenic property of targetedly simulated roadway difference compound, can be accomplished and road surface
Actual state is more nearly.
3rd, the contrast of the not swollen annulus ring crack experiment of different materials：
Prepare base as described above and not swollen annulus, in the present embodiment, respectively from quartz glass, invar alloy and
Ceramics lubricate as the material of not swollen annulus in the lateral wall of the not swollen annulus and the madial wall uniform application of the annular groove
Agent；From 8 kinds of different pitches, it is divided into three groups according to the material of the not swollen annulus of difference and is tested, heated asphalt one is small respectively
When, pouring into respectively in the annular space that base as described above and not swollen annulus are formed, cooling shaping obtains 8 kinds of different pitches
The pitch annulus that material is obtained, strain transducer is set on the madial wall of not swollen annulus described in relative with the cynapse,
Temperature sensor is set at the circular central of base, then resists the pitch low temperature that pitch annulus, not swollen annulus and base are constituted
Fragility energy evaluation structure is put into material height temperature test instrument, and 30min is kept at 0 DEG C, then straight with the speed cooling of 10 DEG C/h
To the fracture of pitch annulus, the ring crack temperature of each pitch annulus is tested and recorded, be broken temperature with 8 kinds of TSRST of asphalt material respectively
Degree carries out correlation analysis, obtains experimental result such as Figure 14, Figure 15 and Figure 16, not swollen annulus pictorial diagram such as Fig. 3 of different materials,
The correlation analysis result of three kinds of bitumen samples ring crack temperature of material and TSRST breaking temperatures obtained by respectively.According to Figure 14, figure
The analysis result of 15 and Figure 16, evaluation method gained ring crack temperature and the TSRST breaking temperatures that the present invention is provided has preferable
Correlation, and using silica glass material gained correlation preferably, and compared to ceramics, invar alloy material, quartz glass
Linear expansion coefficient α is minimum, can be broken quickly asphalt material, and test error is low.Final contrast determines that override is selected
Tested using the not swollen annulus of quartz glass.According to breaking temperature and strain data that experiment is obtained, strain is drawn with temperature
Change curve, such as Figure 17, the jump strain value in figure are the instantaneous strain that not swollen annulus is born when bitumen samples are broken, by
Formula (3.1) stress-strain relation can be obtained,
FNot swollen annulus=εStrain jump value×ENot swollen annulus×ANot swollen annulus (3.1)
In formula：FNot swollen annulusIt is suffered temperature action power on fracture moment not swollen annulus, unit is N；
εStrain jump valueIt is to make the jump strain value of not swollen annulus generation because asphalt material is broken, unit is μ ε；
ENot swollen annulusFor the elastic modelling quantity of not swollen annulus, (quartz glass material, takes E=7.5 × 1010Pa), unit is Pa；
ANot swollen annulusIt is cross-sectional area (A=6.0 × 10 in experiment of not swollen annulus-5m2), unit is m2。
The smearing lubrication of lubricant before being tested and not swollen annulus between due to bitumen samples, the drawing that bitumen samples are produced
Power is equal to not swollen annulus pressure, and both are active force and reaction force, i.e. FNot swollen annulus=FDrip.Therefore, bitumen samples is disconnected
Stress is split to be calculated as follows：
In formula：FDripIt is suffered temperature action power on not swollen annulus, unit is N；
ADripIt is cross-sectional area (A=1.2 × 10 in experiment at asphalt binder sample cynapse-4m2), unit is m2。
σDripAs required ring crack intensity σFrac, correspondence strain projection temperature be ring crack temperature index TFrac。
4th, the ring crack humid test under different pitches difference rate of temperature fall：
Respectively from 110#+5%SBS, 110#, 90#+5%SBS, 90#, 70# this five kinds of asphalt materials respectively according to difference
Cooling rate (1 DEG C/h, 5 DEG C/h, 10 DEG C/h, 20 DEG C/h, 30 DEG C/h) carry out ring crack evaluation of the present invention, from quartz
Glass, from steel base material, obtains ring crack temperature T as not swollen annulus materialFracAnd its experimental result of standard deviation SD
As shown in table 1 and Figure 18.By the experimental result of table 1 can be seen that to five kinds of pitches respectively with 1 DEG C/h, 5 DEG C/h, 10 DEG C/h, 20
DEG C/h, the speed of 30 DEG C/h lowered the temperature, same bitumen difference 3.6 DEG C of maximum temperature difference of rate of temperature fall (90#+5%), minimum temperature
2.1 DEG C (70#), the difference between the ring crack temperature value measured is smaller；Standard deviation to 5 kinds of rate of temperature fall compares, 10 DEG C/h's
The SD averages of rate of temperature fall are relatively small, there is preferably experiment repeatability.
Ring crack humid test result under the different pitches of table 1 difference rate of temperature fall
Claims (8)
1. a kind of evaluation method of pitch crack resistance at low-temperature, it is characterised in that comprise the following steps：
S1：Base and not swollen annulus are taken or prepared, there is an annular groove in the middle of the base, the not swollen annulus closely surrounds institute
State on the internal ring wall of annular groove, the base is provided with a cynapse on the external annulus of the annular groove, the cynapse sets for level
The cylindrical cynapse being placed on the external annulus of the annular groove, the diameter of the cylindrical cynapse can be true according to public formula (I)
It is fixed：
In formula, S represents the diameter of the cylindrical cynapse, and h represents the height of the cylindrical cynapse；R1Not swollen circle described in representing
The outer shroud radius of ring；The H represents the height of the pitch annulus；D determines according to public formula (II)：
In formula, αDripIt is the linear expansion coefficient of pitch；αNECRIt is the linear expansion coefficient of not swollen annulus；Δ T is cooling extent；R1For institute
State the outer shroud radius of not swollen annulus；R2It is the outer shroud radius of the pitch annulus；In formula, parameter εADetermined by public formula (III)：
εA=(αDrip+M·αCollection) Δ T ﹣ M εCollection (III)
In formula, Δ T is cooling extent；αDripIt is the linear expansion coefficient of pitch；M is the length ratio for gathering materials one-dimensional with pitch；αCollectionIt is collection
The linear expansion coefficient of material；εCollectionIt is the strain gathered materials；
S2：Heated asphalt, is poured into the annular space between not swollen annulus and the annular groove external annulus, is cooled to
Type, obtains pitch annulus；
S3：Cooling, until the pitch annulus is broken, detects and records temperature value and not swollen annulus in the position of correspondence cynapse
Instantaneous strain value, the S3's concretely comprises the following steps：Being set on the madial wall of not swollen annulus described in relative with the cynapse should
Become sensor, temperature sensor is set on base, by base, not swollen annulus together with the pitch annulus be put into cooling dress
In putting, then preheating controls heat sink to lower the temperature with steady rate, until the pitch annulus is broken, detects and record temperature
The instantaneous strain value of value and not swollen annulus in the position of correspondence cynapse.
2. the evaluation method of pitch crack resistance at low-temperature according to claim 1, it is characterised in that the S1 and S2 it
Between be additionally included in the not swollen annulus lateral wall and the annular groove madial wall uniform application lubricant the step of.
3. the evaluation method of pitch crack resistance at low-temperature according to claim 1, it is characterised in that also include after the S3
S4：Draw and detect that the instantaneous strain value for obtaining varies with temperature curve, when instantaneous strain value is jumped, corresponding temperature value is
For asphalt material fracture when temperature, i.e. ring crack temperature.
4. the evaluation method of pitch crack resistance at low-temperature according to claim 1, it is characterised in that the not swollen annulus
Linear expansion coefficient≤5 × 10-6mm/mm/℃。
5. the evaluation method of pitch crack resistance at low-temperature according to claim 1, it is characterised in that the not swollen annulus
Material is any one in quartz glass, invar alloy, ceramics and steel.
6. the evaluation method of pitch crack resistance at low-temperature according to claim 1, it is characterised in that the not swollen annulus
Material is quartz glass.
7. the evaluation method of pitch crack resistance at low-temperature according to claim 1, it is characterised in that the material of the base
It is any one in steel, iron, aluminium.
8. the evaluation method of pitch crack resistance at low-temperature according to claim 1, it is characterised in that the cooling in the S3
Velocity interval is 1~30 DEG C/h.
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