• Computers and Concrete
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• v.33 no.5
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• pp.605-619
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• 2024

The increase of reclaimed asphalt pavement (RAP) content in recycled asphalt concrete (RAC) is accompanied by the degradation of low-temperature cracking resistance, which has become an obstacle to the development of RAC. This paper aims to reveal the meso-scale mechanisms of the low-temperature fracture behavior of RAC and provide a theoretical basis for the economical recycling of RAP. For this purpose, micromechanical heterogeneous peridynamic model of RAC was established and validated by comparing three-point bending (TPB) test results against corresponding numerical simulation results of RAC with 50% RAP content. Furthermore, the models with different aggregate shapes (i.e., average aggregates circularity (${\bar{C_r}}=1.00$, 0.75, and 0.50) and RAP content (i.e., 0%, 15%, 30%, 50%, 75%, and 100%) were constructed to investigate the effect of aggregate shape and RAP content on the low-temperature cracking resistance. The results show that peridynamic models can accurately simulate the low-temperature fracture behavior of RAC, with only 2.9% and 13.9% differences from the TPB test in flexural strength and failure strain, respectively. On the meso-scale, the damage in the RAC is mainly controlled by horizontal tensile stress and the stress concentration appears in the interface transition zone (ITZ). Aggregate shape has a significant effect on the low-temperature fracture resistance, i.e., higher aggregate circularity leads to better low-temperature performance. The large number of microcracks generated during the damage evolution process for the peridynamic model with circular aggregates contributes to slowing down the fracture, whereas the severe stress concentration at the corners leads to the fracture of the aggregates with low circularity under lower stress levels. The effect of RAP content below 30% or above 50% is not significant, but a substantial reduction (16.9% in flexural strength and 16.4% in failure strain) is observed between the RAP content of 30% and 50%. This reduction is mainly attributed to the fact that the damage in the ITZ region transfers significantly to the aggregates, especially the RAP aggregates, when the RAP content ranges from 30% to 50%.

• Geotechnical Engineering
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• v.12 no.3
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• pp.17-34
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• 1996

The objective of this paper is to evaluate the asphalt mixture performance with pyrolyzed carbon black(CBP) and air -cooled iron blast furnace slag. Marshall mix design was performed to determine the optimum binder content, The optimum binder content ranged from 6.3 percent to 7.75 percent. Dynamic creep testing was carried out using mixtures at the optimum binder content. Based on the test results, the use of pyrolyzed carbon black and slag in the asphalt pavement showed a positive result, such as the increase of Marshall stability, the decrease of the strain rate and the decrease in the mix stiffness rate at high temperature(5$0^{\circ}C$) and 137.9 kPa confinement. Within the limits of this research. it was concluded that pyrolyzed carbon black as an additive and slag as a coarse aggregate could be used to produce an asphalt paving mixture that has good stability, stiffness, and rutting resistance.

• International Journal of Highway Engineering
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• v.7 no.1 s.23
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• pp.63-71
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• 2005

Asphalt binder grading is to specify quality of asphalt binders relating to pavement performance in orderly manner, and provides the necessary information in selecting the appropriate asphalt binder for the hot mix design. For this purpose, United States has developed the PG-grading in 1995 and is implementing in practice. Recently, this American PG-grading system has been accepted as the domestic binder grading specification. However, the Asian (including Japan and China) and the most European countries are still use the traditional penetration and viscosity specification. The goal of this study lies in analysing the American PG-grading for its justification. As the result, the serious errors are found, and thus, to eliminate the errors, the more precise binder grading equation is introduced, Credibility of this study is checked by predicting the literature rut data with the equations mentioned. The prediction result are validating the claimes made in this study.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.9-20
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• 2011

Most of domestic expansion joint system was applied by exposed expansion joint system. There are cases where it is damaged by driving. As the result noise and impact happened, and the social cost due to frequent repair works is increasing. So based on the Asphalt Plug Joint(APJ) system that applied in the United States and Europe, new buried expansion joint system was lately developed a system of Buried Folding Lattice Joint(BFLJ) that changed substructure. In this research, we have tested for durability and flexibility performance of buried expansion joint system that based on the type of asphalt mixture. Also we have evaluated for durability of BFLJ system against vehicle load using accelerated pavement testing. As a result of the experiment, the developed BFLJ system gives high flexibility performance and resolves transformation concentration along the joint section more than APJ system. Also it could be seen that the BFLJ system could overcome the disadvantages of APJ and prevent early damage. Because surface deflection of BFLJ system against vehicle load was measured low, and sub system in the buried expansion joint system was not damaged against vehicle load.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.1-8
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• 2011

The objective of this paper is to evaluate the performance of low $CO_2$ asphalt binder properties using LEADCAP$^{(R)}$(Low Energy and Carbon Asphalt Pavement) additive as function of various aging methods such as RTFO(Rolling thin film oven), Ultraviolet(UV) lay. In order to simulate the short-term aging of asphalt binder that occurs during the hot-mixing asphalt process, the Rolling Thin Film Oven(RTFO) was used. Asphalt binder using LEADCAP$^{(R)}$ is prepared by addition of a photoinitiator activated by ultraviolet lay. The mechanical and rheological properties of the asphalt binder were estimated using UTM(Universal Testing Machine) and DSR(Dynamic Shear Rheometer). The test results showed that the asphalt binder using LEADCAP$^{(R)}$ additive was improved the rutting resistance at testing temperature ($70^{\circ}C$) and increased tensile strength at low temperature. Also, Thermal analysis shows that the Melting Point(Tm) of asphalt binder using LEADCAP$^{(R)}$ additive was constant although the asphalt binder was aged by Ultraviolet.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.3
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• pp.29-38
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• 2020

Since some warm-mix asphalt (WMA) concretes were known to show poorer rut resistance than the hot-mix asphalt (HMA) concretes, many studies were performed in efforts of improving its performance at high temperature. The reason is assumed to be due to the moisture remaining in aggregates dried at lower temperature. Therefore, not only the rut resistance, the crack resistance of WMA concrete was also in question. In this study, fatigue life of WMA concrete was evaluated in comparison with HMA using 3-point bending (3PB) beam test. The asphalt mixtures were prepared based on Korean mix-design guide using a 13 mm dense-graded aggregate and 6 binders; two HMA binders and four WMA binders. By 3PB fatigue test, normal (unmodified) and polymer-modified WMA concretes were evaluated in comparison with normal and polymer-modified HMA concretes at a low temperature (-5℃). The results showed that most of WMA concretes showed longer fatigue lives than HMA concretes, even though the same PG binders were used for HMA and WMA. This result indicates that the WMA concretes have stronger resistance against fatigue cracking than HMA at the low temperature, and this result is in contrast to the high-temperature performance test.

• International Journal of Highway Engineering
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• v.4 no.3 s.13
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• pp.15-23
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• 2002

The waterproofing system's performance is known to show a determing by complex interaction of material factors, design details, and the quality of construction, and the waterproofing integrity of waterproofing membranes is determined by the bond to the deck and the amount of damage to the waterproofing membrane. In this research, the basic properties of waterproofing membranes on market and the tensile adhesive chracteristics of waterproofing systems of concrete bridge deck have also been investigated in the view of the damages frequently reported from job site. For the tensile adhesive strength of sheet waterproofing membranes, the results after asphalt concrete paving tends to increase more than before those. The results of the liquid waterproofing membranes are upside-down, and the more concrete has strength, the more strength of tensile adhesive increase. The ambient temperature of asphalt concrete when application of the waterproofing membrane has considerable influence on the performance of waterproofing system. As described above, waterproofing system can be influenced by several factors. If they are not considered under construction, the overlooking will cause the damages of pavement and waterproofing system after traffic opening.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.25-31
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• 2009

In general, it is well known fact that the stone mastic asphalt (SMA) pavement has a high resistance against rutting. However, performance of SMA is not well measured by general method used in the laboratory. The objective of this study is to investigate an applicability of deformation strength ($S_D$) for performance estimation of SMA, and to find out the correlation between rut depth and dynamic stability, and $S_D$ of SMA. This study carried out wheel tracking test and Kim-test with optimum asphalt content (OAC) determined by mix design. The results indicated that the $S_D$ of SMA was very poorer than those of dense-graded asphalt mixtures. $S_D$ showed similar WT dynamic stability and rut-depth level. It was found that Kim-test was not reflected higher rutting resistance of SMA like as indirect tensile strength (ITS) test and Marshall stability test. Also, it was revealed that dynamic stability and rut-depth of WT had some problems to estimate rutting resistance of SMA mixtures.

• International Journal of Highway Engineering
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• v.2 no.2
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• pp.129-138
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• 2000

This study presents the mechanical characteristics, such as the permanent deformation and the crack, of the large stone asphalt mixtures. The large stone mixture was studied by Kandhal at NCAT(National Center for Asphalt Technology) in 1989. Japan and Arabian countries adopted the large stone mixture for the pavement construction. The experience and the study results showed that the interlocking of the aggregate system of the large stone mixtures is stable and less dependent on the binder characteristics in high temperature. These properties are known as the rutting resistant parameters. However, the mechanical test results should be supported to prove the benefits of the large stone mixtures. The creep test, resilient modulus tests on three different temperature, wheel tracking test and ravelling tests were conducted to evaluate the performance of the large stone mixtures in this study. The test results were compared with the conventional mixtures and modified asphalt concrete mixtures. The large stone mixtures showed better rutting resistance performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.3
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• pp.13-20
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• 2021

Post-installed anchor is a structural material that connects structural and non-structural members to existing concrete members. However, there are cases where rebar interception and construction error occur at the site. In that case, measures are needed to prevent performance degradation of the rear-installation anchors. In this study, in order to evaluate the performance of torsional control expandable post-installed anchors for compressive strength and effective depth of the reference concrete was tested. The results of the most commonly used tests of M10 and M20 showed that had variable coefficients within 15%, satisfying the reliability presented in KCI(2017). It was also confirmed that the depth of the buried and the strength of concrete affect the strength of the pavement. Based on the results of the existing similar studies and the results of this study, the design equation of the post-installed anchor was proposed and the results were compared with the existing design.