Performance Characteristics of Asphalt Paving Materials Application of the Distributed Energy Theory to Estimate the Fatigue. Application of the Dissipated Energy Theory to estimate the fatigue characteristics of hot and hot recycled SMA mixes. Four-point bending fatigue test is performed on the recycled mixtures, and the displaced energy theory is employed to analyze the fatigue characteristics of the recycled mixtures.
Therefore, to extend the service life of the asphalt pavement, the fatigue characteristics of the mixtures should be considered.
OBJECTIVE AND RESEARCH SCOPE
PROPETTIES OF MATERIALS 1 Properties of RAP
DESIGN OF THE HOT AND WARM RECYCLED MIXTURES
Design of the hot recycled mixtures
Design of warm recycled mixtures
FATIGUE CHARACTERISTICS OF THE HOT AND WARM RECYCLED MIXTURES
Fatigue scheme for the hot and warm recycled mixtures
Test results and analysis
The cumulative energy dissipations of the hot and hot recycled mixtures in Table 8 are plotted in a double logarithmic coordinate and subject to exponential adjustment. Fig.2 The cumulative dissipated energy of the hot and warm mixtures during their fatigue life. Therefore, the fatigue characteristics of the hot and warm recycled mixtures can be assessed by their cumulative dissipated energy.
This is mainly because RAP has a negative impact on the life of the recycled mixture.
CONCLUSIONS
8. for the recycled mixtures with RAP, the addition of Sasobit leads to a lower mixing temperature, which facilitates the aging of both the old and the new asphalt, so that the fatigue life of the recycled mixtures is improved to some extent. Low RAP will cause less impact on the fatigue properties of the recycled mix; high RAP will reduce the fatigue life of the recycled mix.
ACKNOWLEDGMENT
Where Z(x) is the function describing the surface profile analyzed in terms of height (Z) and position (x) of the sample over the evaluation length "L". Summary: Aging of asphalt binders causes changes in the microstructure of the asphalt binders, and consequently in the mechanical properties. The PBST is then used to measure the tensile strength of the bonding layer material.
The adhesive strength classification of different asphalts is: PG 70-22 (SBS modified asphalt) > Asphalt rubber > PG 64-16 (Basic asphalt) >.
Bond lowing point
Reapted creep recovery test (RCRT) .1 Method and equipment
To calculate the continuous section of the creep stiffness that evaluates the high temperature performance of asphalt, the test results of the 50th and 51st loops were fitted according to Burger's model. In this study, the creep recovery deformation figure for the 50th cycle was analyzed, also the creep stiffness modulus (CSM) parameter was obtained for S(t)=τ0/ε(t), where τ0 is the shear stress at a cash load, ε(t) is load and t is time. For the parameters of the power function S(N)=a*N-b, the increase of the value a and the decrease of the value b can reflect the temperature sensitivity.
With temperature rise, the value of stiffness modulus for fiber mastic is reduced and the rate of change of modulus is increased, decreasing the ability of permanent deformation resistance.
Multi-stress creep recovery test (MCRT) .1 Test brief
The comparison of average strain recovery rate R(100) for 10 cycle numbers was determined by. 2) The comparison of irrecoverable creep compliance Jnr for each cycle was determined by. Due to the fiber added to asphalt mastic, the high temperature performance of fiber asphalt mastic is improved compared to that of pure asphalt mastic. For the heavy load, fiber can improve the recovery rate of mastic deformation and reduce the residual stress after unloading, which has a positive impact on the performance of asphalt mastic in high temperatures.
CSM of different fiber types have differences, a reduced order follows basalt fiber, polyester (PL) fiber, glass fiber, pure mastic[control]. 3) With increased stress, the CSM of fiber asphalt mastics decreases.
Bending creep stiffness test (BCST) .1 Test brief
When the stress is low, the rate of change of CSM is obvious, but as the stress increases, it is gradually reduced to stable. For the 10th cycle, the relationship between CSM and stress can be expressed by the logarithmic function S(F)=-c*ln(F)+d, the results are shown in Table 5, where F represents the fiber types.
Loading
- Raw materials .1 Aggregate evaluation
- Hard paving grade asphalt
- Mixture design
- Mixture performance evaluation .1Fatigue and modulus properties
- High temperature performance
The initial oil-rock ratio is 5.6%, the calculated wealth modulus K=3.76>3.4, meets the requirements of engineering technology. Using the French standard of gyratory compaction 100 times to form, the bulk density porosity of the high modulus mixtures of basalt is 2.9%, limestone is 1.1%, further key research on the performance of limestone is high temperature, modulus and fatigue resistance. It was demonstrated that with the same oil-to-stone ratio (such as 5.9%), the fatigue resistance performance of the high-modulus mixture designed with limestone could meet the specification requirements of an average load of more than 1 million cycles, but if load cycles of the mixture formed by the basalt reached 1 million, the oil-stone ratio must reach more than 6%.
For basalt-aggregate mixture, although the oil-stone ratio is at 6.1%, the spore deformation rate does not exceed 6%.
Typical fo
PEEL
- INTRODUCTION
- SAMPLE PREPARATION AND PROBE SELECTION
- Sample preparation
- Working mode and Probe selection
- STRUCTURAL CHARACTERIZATION OF THE BITUMEN
- Experimental
- Fatigue Performance Comparison at Design Air Void
- Fatigue Performance Comparison at the Same Asphalt Content
- Fatigue Equation
- Self-healing Ability Comparison at Design Air Void
- Self-healing Capacity Comparison at the Same Asphalt Content
Complex modulus and fatigue resistance of mixtures appeared to vary significantly depending on the nature of the base binder. Statistical analysis of the influence of RAP and mix composition on viscoelastic and fatigue properties of asphalt mixtures." Mater. Statistical analysis of the influence of mix design parameters on mechanical properties of asphalt mixtures with reclaimed asphalt pavement materials." Transport.
However, the problem is that the shape and thickness of the sample were not the same as shown in Figure 3. The AFM sample must be thick enough to avoid the effect of the substrate on the bitumen microstructure. AFM is an indispensable instrument that can provide the microstructure of bitumen at the nanometer level.
In addition, the QNM properties of the bitumen will be a very important topic in the research of pavement materials. SBS modified asphalt mixture is the most widely used modified asphalt mixture in the surface course of the highway in China. Compare the fatigue life of the three asphalt mixtures at the design air gap and compare the fatigue performance of asphalt mixtures at the same asphalt content.
Fatigue life is sensitive to the effect factor when the absolute value of the parameter before it is high. Increasing the content of fine aggregate, mineral filler and the asphalt content are effective methods to improve fatigue performance. In this study, CRMA mastic was produced according to the parameters. The parameters are listed in Table 2.
Laboratory tests were performed to characterize and compare the high-temperature properties of CRMA putty with the addition of mineral dust and cement.
INTRODUCTION
After that, the mixture begins to age during service for a longer period of time, which is called long-term aging (LTA). It is generally agreed that the longer the lifespan, the higher the level of aging. However, from the study of the aging level of highway asphalt pavements in Korea, a significant difference in the LTA level between two types of asphalt mixtures [rock-cast asphalt (SMA) and dense-graded asphalt (DGA)] was detected.
To investigate this finding more fully, the works were extended to artificial aging of SMA and DGA blends. STA was performed for 1 h at 160 ℃ on the loose mixture, which was mixed with a paddle mixer, and then LTA was performed for 48 and 72 h at 110 ℃ on the samples made from STA-treated mixtures. The level of aging was evaluated by the gel-permeation chromatography (GPC) test in terms of large molecular size (LMS) directly from the mixture particles.
To further investigate this result, the works were extended to the artificial aging of SMA and DGA short-term aging (STA) blends for 1 hour [STA(1)] at 160 ℃ on the loose blends mixed with an optimal asphalt content (OAC) by a paddle mixer. The long-term aging was also performed for 48 and 72 hours [LTA(48) and LTS(72)] at 110°C on the compacted sample prepared with an STA mixture to simulate long-term field aging. The gel permeation chromatography (GPC) was used to evaluate the level of aging in terms of the percentage of large molecular size (LMS) measured directly from the mixture particles for GPC sampling.
The objective of this study was to evaluate the binder aging characteristics of SMA mixes compared to those of DGA mixes based on LMS values which can be related to binder viscosity and stiffness. Statistical analyzes were performed to find any significant differences between the mixture types (SMA and DGA).
MATERIALS AND METHODS
DGA 5.2
SMA 6.4
DGA 4.7
- The Simplified State of RAP based on Smaller Variation Degree of Gradation According to "Technical Specifications for Construction of Highway Asphalt
- The Simplified State of RAP based on Bigger Variation Degree of Gradation In this paper, the influence of high content of RAP on gradation design was also
- Only some of the measurement results (mainly total permanent deformation or rutting) are presented in this paper due to the length limit. More details can be found
In addition to the binder property, the service life of the pavement was analyzed in relation to LMS. The concept of "variation degree of gradation" was proposed to quantify the uncertainty of the recovered mixture gradation. In fact, in any kind of recycling mix, the state of the RAP must be incomplete mixing state.
Comparison diagram of pre-extraction and post-extraction outcome screening of 0-5 mm and 5-15 mm RAP. This paper provided the "rate of gradation change" to quantify the gradation uncertainty of the recycled mix. The high temperature performance of the mixture is based on the two gradation design methods. description of the test phenomenon.
1) Different simplified condition of RAP will lead to uncertainty of warm recycled asphalt mix gradation, and this uncertainty can be quantified by. The water level was approximately maintained at the approximate top of the substrate for the duration of the wet test. The graph of the average water level measured in the 950 mm sub-section is shown in the figure.
The sensitivity of the pavement structure to water (i.e. standing water in the subsoil) and to load is clearly visible. The thickness of the subbase affected tracking behavior and groove depth in the different layers. 34; Laboratory Characterization of Contaminated Railway Ballast Behavior.” Transportation Research Record: Journal of the Transportation Research Council.
34; An Investigation of Aggregate Properties Affecting Railroad Ballast Performance.” Transportation Research Record: Journal of the Transportation Research Board.
