Sustainable Pavement Material Research Articles

Recyclability potential of waste plastic-modified asphalt concrete with consideration to its environmental impact

The use of waste plastic into asphalt concrete paving mix (ACP) has been explored in recent literature to improve the functional properties of the mix. However, exploration on their recyclability potential at the end of its service life remains scarce. This study explores the potential of recycling aged waste plastic-modified asphalt concrete (AACP) for road pavements, with focus on four commonly disposed household plastics: high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS) and polyethylene (PET). Marshall stability test, Cantabro abrasion test, indirect tensile strength test, resilient modulus (MR) test, Hamburg’s wheel tracking test and stripping test were performed to evaluate the engineering properties of recycled waste plastic-modified asphalt concrete (RACP) containing proportions ranging from 20 % to 100 % aged component (AACP) blended with virgin mixtures. This paper highlights significant engineering performance of RACP, and most notably for RACP containing PP with 20 % aged content which exhibits 1.6 times greater resistance to moisture damage compared to conventional recycled asphalt concrete (RAPA). Although RACP with HDPE and PP (consisting of 20 % and 40 % AACP in mix) yield improvements in resilient modulus over RAPA, this improvement is less pronounced for RACP with PS and PET. Overall, RACP with 40 % aged components exhibits better rutting, moisture damage and abrasion loss performance, along with improved stability and flow value. Environmental impact in terms of water leachability was also found to be negligible in this study and RACP can be considered a feasible sustainable pavement material, with potential for second and more lives.

Sustainable development of pavement base stabilization using future road base material (FROBM)

Sustainable road construction has emerged as a critical issue in assessing natural resources and urban development. With the rapid expansion of pavement networks to meet growing traffic demands, road base construction relies heavily on the consumption of natural aggregates and Ordinary Portland Cement (OPC) through the cement-treated base (CTB) technique. This practice contributes to the global warming and greenhouse gas (GHG) emissions associated with road construction. This study investigated a novel road base material, Future Road Base Material (FROBM), which emphasizes both eco-friendliness and economic advantages. Fine crushed rock (FCR) served as the parent aggregate and was modified with a chemical binder comprising 4% of the FCR weight. The proposed sustainable cementitious material, functioning as a non-OPC binder, incorporated fly ash and hydrated limestone as pozzolanic materials, along with sodium hydroxide (NaOH) as an alkali additive. An asphalt emulsion (AE) was employed as a special additive to enhance crucial pavement engineering properties. Through life cycle analysis (LCA), the construction activities and material acquisition of each stabilized base technique were evaluated in terms of project costs and carbon footprints. The non-OPC binder offered sufficient compressive strength for a stabilized base course. Furthermore, the addition of AE improved the elastic modulus and modulus of rupture of the non-OPC binder-stabilized mixture. Utilizing a non-OPC binder and AE in the base layer provides advantages in terms of construction cost and environmental impact. Although the costs increased slightly, the GHG emissions were reduced by approximately 30% compared to conventional base materials, with equivalent functionality and service life for road construction. The proposed stabilizing agent reduced the operational processes and demand for natural aggregates compared with the unbound FCR base course. Road-base stabilization using a non-OPC binder and AE represents an innovative approach to mitigate waste in coal mining and power plant industries by transitioning to a cleaner product. The concept of the FROBM serves as a valuable guideline for the development of future sustainable pavement materials.

The role of bio-based additives in achieving sustainability in asphalt pavements

Increased service demands from asphalt pavements due to ever-increasing volumes, coupled with the aging of highway networks, and calls for improved sustainability across the industry, have rendered the need for smart and sustainable pavement material and design more important than ever. While chemical warm mix additives and rejuvenating technologies have been utilized in pavement materials at various scales of research and practice in the past, in recent years bio-based additives have emerged as increasingly practical solutions for potentially achieving more sustainable pavements, offering the prospect for high performance combined with environmental and economic sustainability. Adaptation of chemical warm mix additives and rejuvenators in practice requires a working knowledge on the definitions, relevant evaluation criteria available to the practitioner, and, perhaps most importantly, demonstrated experience of successful application in practice. The present study will review current efforts underway in the industry to incorporate bio-based chemical warm mix additives and rejuvenators in performance-based design methods for HMA and WMA, using real world Balanced Mix design (BMD). Examples including comprehensive research being carried out in conjunction with NCAT and MnROAD research and test facilities will be reviewed to illustrate the utilization of such concepts in practice today.

Application of bio-resin in road materials: Rheological and chemical properties of asphalt binder modified by lignin-phenolic resin

The development of new sustainable green road materials with bio-resin is a hot topic in pavement engineering. To improve the efficiency of lignin as a sustainable pavement material, an asphalt binder modified by lignin-based resin was prepared, and its properties were evaluated. Firstly, lignin was extracted from biomass (corn straw) by thermochemical method to prepare lignin-based phenol formaldehyde (LPF) resin. After that, LPF resin-modified asphalt and phenol formaldehyde (PF) resin-modified asphalt were prepared. Then the effects of LPF resin and PF resin on asphalt properties were evaluated by chemical analysis and rheological performance tests. The results showed that lignin was involved in resin synthesis, LPF resin with PF resin had similar thermogravimetric curves, and the thermal stability of LPF resin was slightly lower than PF resin. Both LPF resin and PF resin can increase the proportion of large-size molecules and elastic components of asphalt binder and enhance its high-temperature deformation recovery ability. Moreover, the fatigue performance and aging resistance of the binder were also enhanced by the addition of LPF resin and PF resin. Although the addition of LPF resin and PF resin will increase the G-R parameters of virgin asphalt binder, it can reduce the effect of aging on the G-R parameters of asphalt binder. It seems that LPF resin and PF resin can improve the cracking resistance of asphalt binders.

Investigation of the performance and micro-evolution mechanism of low-content thermosetting epoxy asphalt binder towards sustainable highway and bridge decks paving

The reduction of epoxy resin (EP) content in the thermosetting epoxy asphalt binder can contribute to decrease the cost and carbon emissions, whilst promoting the diversification of their application scenarios. In this study, the performance and microstructure of low-content thermosetting epoxy asphalt (LTEA) binders with EP contents between 30 wt% and 40 wt% were investigated through macroscopic and microscopic methods, and the mechanism of strength formation was simultaneously explained. Moreover, the curing degree of the LTEA binder and the mixture were investigated by Fourier transform infrared spectroscopy (FTIR) and the Marshall test, respectively, and their correlation was established. The results revealed that the mechanical strength of the LTEA binder was enhanced by increasing the EP content, and the LTEA36 binder had good tensile properties. The cross-sectional morphology and microscopic phase distribution of the LTEA binder changed significantly when the EP content increased. The phase transition occurred within the LTEA34 binder, which formed a cross-linked network with EP as the continuous phase. The curing degree of the LTEA binder for 24 h was higher than 75%, which corresponded favorably to the curing degree of the mixture. In general, the curing degree of the binder can be used to identify whether the strength of the pavement mixture has reached the specification and reduce the damage to the completed pavement. Additionally, compared to the epoxy asphalt binder with 50 wt% EP content, the cost and carbon emissions of the LTEA36 binder were reduced by 24.8% and 26.3%, respectively. The LTEA36 binder has excellent potential to become a sustainable pavement material for high-grade highways and concrete bridge decks.

The synergistic effect of waste engine oil and organic montmorillonite on properties of bitumen: Conventional, high-temperature rheological, and self-healing

In order to conserve non-renewable natural resources, recycling waste engine oil (WEO) in bitumen can help lower CO2 emissions and advance the environmental economy. This paper makes an effort to investigate the viability of WEO and organic montmorillonite (OMT) to enhance the high-temperature rheological and self-healing of bitumen binder. Conventional tests and dynamic shear rheology (DSR) test were used to examine the influence of WEO/OMT on the traditional performance and high-temperature rheological properties. Based on a fatigue-healing test, evaluation indicators such as fatigue life recovery (FLR), modulus recovery (MR), and dissipated energy recovery (DER) were chosen to determine the degree of healing of bitumen. The mechanism was revealed by the atomic force microscope (AFM). Finally, a radar chart was employed to analyze the comprehensive properties of WEO/OMT modified bitumen. The results indicate that WEO modified bitumen loses ductility and penetration when OMT is added while increasing softening point and high-temperature performance. Compared to original bitumen, the rutting factor of bitumen modified with 3% WEO and 2% OMT has the most significant increase by 31.2%. The performance of the bitumen binder during fatigue and self-healing is improved by the addition of OMT and WEO. Regardless of the OMT level, bitumen modified with 9% WEO shows a significant improvement in FLR, MR, and DER compared to the original bitumen. In conclusion, the inclusion of WEO/OMT in bitumen offers a fresh approach to developing sustainable pavement materials.

The Synergistic Effect of Polyphosphates Acid and Different Compounds of Waste Cooking Oil on Conventional and Rheological Properties of Modified Bitumen

In order to conserve non-renewable natural resources, waste cooking oil (WCO) in bitumen can help lower CO2 emissions and advance the environmental economy. In this study, three different components of WCO were isolated and then, together with polyphosphoric acid (PPA), used separately as bitumen modifiers to determine the suitability of various substances in WCO with PPA. Conventional tests, including penetration, softening point temperature, and ductility, and the dynamic shear rheology (DSR) test, including temperature sweep and frequency sweep, were used to evaluate the influence of WCO/PPA on the traditional performance and rheological properties at high and low temperatures. The results indicate that WCO reduced the ductility and penetration value, when the use of PPA increased the softening point temperature and high-temperature performance. Compared to reference bitumen, the rutting factor and viscous activation energy (Ea) of bitumen modified with 4% WCO and 2% PPA has the most significant increase by 18.6% and 31.5, respectively. All components of WCO have a significant impact on improving the low-temperature performance of PPA-modified bitumen. The performance of the composite-modified bitumen at low temperatures is negatively affected by some waxy compounds in WCO, such as methyl palmitate, which tends to undergo a solid-liquid phase change as the temperature decreases. In conclusion, the inclusion of WCO/PPA in bitumen offers a fresh approach to developing sustainable pavement materials.

A Multifunctional and Sustainable Pavement Material: Pervious Concrete

Pervious concrete (PC), as sustainable pavement material, has gained a lot of attention as a result of its specific environmental effects. This manuscript analyzes the advancements and state-of-the-art pertinent to PC research and practices. This review focuses on the utilization of various waste components (used as aggregate) in PC, its composition and specifications, mechanical strength and durability, pore properties and clogging behaviour; in-situ applications and the future scope of the material. The unique ability of PC addresses a number of environmental interests ex: ground water recharging, water runoff mitigation, controlled heat island effect, decrease in risk pertaining to flash flooding runoff, noise reduction, etc. The multitudinous benefits of PC paves a way for further investigations to understand the material functionality in a better way and make it a promising sustainable construction material in future.

Study on preparation and performance of a thermosetting polyurethane modified asphalt binder for bridge deck pavements

With the rapid development of traffic volume and loading, sustainable pavement materials are developing to improve the longevity of orthotropic bridge deck pavement structures. This paper aims to develop a new flexible binder with improved mechanical characteristics for bridge deck applications. This research studied the preparation process, microstructural morphology, and mechanical properties of a newly developed thermosetting polyurethane modified asphalt binder (TPUA). The results showed that the viscosity of TPUA was greatly affected by the preparation temperature and the viscosity growth rate increased with the increase of preparation temperature. The curing time was determined by the change in the absorption peak of the infrared spectra of the NCO groups. When the content of the PU modifier exceeded 30 wt%, the polyurethane (PU) resin formed a continuous polymeric network in asphalt binder, and the PU had relatively good compatibility with the asphalt binder. TPUA still showed the characteristics of a viscoelastic material at medium and low temperatures. When the content of PU exceeded 30 wt%, TPUA gradually showed the characteristics of an elastic material at high temperature and had excellent high-temperature deformation resistance and elastic recovery properties. In addition, the TPUA binder showed improved low-temperature flexibility with the increase of PU. Overall, the mechanical properties of the asphalt binder were substantially enhanced with the incorporation of PU resin, generating a flexible binder with favorable application prospects.

Discrete element method to investigate flexural strength of pervious concrete

Pervious concrete (PC) is a sustainable pavement material that has been widely used for low volume roads, walkways, and bicycle paths. Past literature studies have proposed several mix design methods to prepare PC with desired properties. However, the current mix design procedure involves substantial consumption of materials and is labor-intensive iterative process. Several numerical simulation studies used discrete element method (DEM) in simulating PC as a granular material (aggregates) coated with cement paste. Even though several researchers investigated mechanical properties such as compressive, flexural, and tensile strengths in the laboratory, and simulated the behavior of PC under compression and tensile loads, no known study has attempted simulating flexural response of PC. Given the significance of flexural strength in the pavement design process, it is essential to simulate the flexural behavior of PC. Therefore, the objective of this study was to develop a DEM framework to simulate PC mixtures and predict their flexural behavior by simulating the flexural strength test in a DEM based software YADE. A laboratory experimental program was conducted to obtain the experimental data required for calibration and validation of the proposed PC simulation model. In addition, a DEM program was developed to simulate the PC mixtures with the desired gradation and porosity levels, as achieved in the laboratory. A flexural strength test similar to ASTM C78 (1 MPa/s loading rate) was devised to simulate the flexural behavior of the prepared numerical PC specimens. The cohesive particle model in YADE was calibrated using experimental data and then used as the constituent model to simulate the interaction between cement coated aggregates in these flexural strength simulations. Overall, the proposed DEM approach could simulate the PC specimens with specified porosities and was able to predict the flexural response of the PC mixtures at 97% accuracy. It is envisioned that the proposed model could be further used to design PC mixtures with desired porosity and flexural strength properties instead of preparing trial mixtures, which would substantially reduce wastage of materials and human effort.

Preparation of solid-waste-based pervious concrete for pavement: A two-stage utilization approach of coal gangue

As the most discharged solid waste in China; coal gangue (CG) occupies a considerable amount of land and severely pollutes the environment. Large-scale production, low added value of products, and lack of innovative disposal methods have lead to the difficult situation of effective utilization of CG. Therefore, it is very important to develop new ways to utilize CG on a large scale and with high-valued. This paper proposes a new method for reducing the environmental burden and realizing a high-value utilization of CG. The study was based on a two-stage utilization approach. Raw CG was first used to prepare solid-waste-based sulfoaluminate cement (WSAC). Then the prepared WSAC combined with self-ignited coal gangue (SCG) was used to prepare a high-strength pervious concrete (HSPC). The mechanical properties, mineral composition, and microstructure of the prepared WSAC clinker were analyzed. The results show that mortar from the prepared WSAC clinker had a reasonable mineral composition, well-developed crystals, and a compressive strength of 55.2 MPa at three days, which meets the standard for 52.5 N ordinary Portland cement. Furthermore, the influence of the water-binder (W/B) ratio, a ggregate-binder (A/B) ratio, and different SCG content on the performance of HSPC was studied. It was observed that the optimal HSPC was prepared when the W/B ratio and the A/B ratio were 0.22 and 4.0, respectively. Compared with traditional pervious concrete, the prepared HSPC has both high strength and high water permeability, and the obtained compressive strength is 34.8 MPa, a connected porosity of 19.80%, a water permeability of 7.95 mm/s, and a hardening density of 1930.8 kg/m3. An SCG content of 10%–20% was considered to the best dosage range for the preparation of HSPC. Furthermore, the freeze–thaw cycle analysis and abrasion resistance test indicated that HSPC with 10% SCG content has acceptable durability. Finally, the environmental impact of HSPC was evaluated through heavy-metal leaching tests, revealing that HSPC has a good curing ability on heavy metals and the leaching index was lower than the limit specified by the regulations, which reflects the environmental friendliness. Thus, this paper presents a low-cost and promising method for the resourceful utilization of CG and production of a sustainable pavement material. In addition, further research is needed before the application of this material to explore its durability and practicality in a specific environment.

Rheological Findings on Storage Stability for Chemically Dispersed Crumb Rubber Modified Bitumen

Elastomers and different Plastomers are most common additives used to improve the performance of binder. However, bitumen modified with these additives is known to be unstable followed by the problem of separation. The separation problem becomes worse, when bitumen is modified with CR, which can undergo a high degree of phase separation during hot storage. The incorporation of CR reclaimed from waste tyres resulted in enhanced properties of conventional bitumen but with limited constraints. Scrap tyres is taken as important product followed by its effective use with virgin bitumen in order to rectify the mechanical and performance properties of base bitumen.The changes in densities of material constituents also affected the storage stability of blends. It is also dependent on the phase separation and dispersion of CR particles for storage intervals. The improved storage stability was attributed to a good CR dispersion which was also observed during softening point and X-Ray image analysis resulting into improved performance for experimented temperatures. Besides, the involvement of DDSA imparted with the significant change in the performance of blends against storage stability. The study is based on empirical techniques to be adopted as revolutions for smart and sustainable pavement materials.

Improvement on the high-temperature stability and anti-aging performance of the rubberized asphalt binder with the Lucobit additive

Applying waste tire rubber powder to modify the asphalt binder is a promising protocol to achieve sustainable pavement materials. This study aims to examine the feasibility of using Lucobit type asphalt additive in the rubberized asphalt and further enhance its performance. The 90# asphalt binder and the rubber powder with 30 mesh were selected to prepare the rubberized asphalt. Two Lucobit adding ratios (5% and 10%) were then selected for the modification of three types rubberized base binder (Rubber replacement ratios 15%, 20%, and 25%). The modified asphalt binder was prepared under 180 ± 5 ℃ by using the high-speed shear mixer under 5000 rpm for 2 h. Then the FTIR and TGA tests were conducted for the phase analysis of the asphalt co-modified with rubber powder and Lucobit. The test results indicated the modification mainly belong to the physical blending instead of chemical bonding. Further study with DSR test indicated the added Lucobit can further enhance the high-temperature stability of the rubberized asphalt. Further study based on Multiple Stress Creep Recovery (MSCR) test indicated the anti-rutting performance of the asphalt binder would be enhanced while the sensibility of asphalt binder to shear stress would be reduced with the added Lucobit. Finally, the topography analysis on the original and aged binders were analyzed with Atomic Force Microscopy (AFM) test. The results indicated obviously reduced bee-like structure can be observed in the samples with Lucobit, which is in accordance with the measured complex modulus after aging tests. Overall, this study indicates the addedLucobit can further enhance the high-temperature stability, antiaging performance, and reduce shear stress sensitivity of the asphalt binder.

Experimental study of soda lignin powder as an asphalt modifier for a sustainable pavement material

In recent years, lignin has been receiving more coverage as an asphalt modifier because of its wide variety of sources, low price, renewability, and potential to improve the performance of asphalt pavement. This research aims to develop lignin-modified asphalt by adding soda lignin powder in different proportions to overcome some drawbacks of traditional modified asphalt. A series of tests, including empirical, viscosity, rutting, fatigue, cracking, storage stability, and chemical tests, were performed to determine the influence of soda lignin on asphalt binder. Test results revealed that the addition of lignin helps to reduce the temperature sensitivity of the asphalt by increasing its hardness and decreasing its ductility. At the same time, the incorporation of soda lignin powder also increased the viscosity of base asphalt with the increase in lignin content. Furthermore, rheological performance test results revealed that the addition of soda lignin significantly enhanced the rutting resistance and fatigue performance for all the dosages incorporated. And also, a slight reduction in low-temperature cracking performance was observed. In addition, the storage stability test result depicted that the dispersion of lignin powder in asphalt was comparatively uniform and stable, indicating excellent thermal storage stability for all the lignin amounts incorporated. Moreover, chemical test results suggest that the soda lignin and bitumen can be mixed physically without new chemicals.

Utilization of Palm Oil Mill Residue as Sustainable Pavement Materials: A Review

The advances in industrial technology have led to a major rise in the amount and forms of residue, especially during the processing of agricultural products. With the paradigm shift towards renewable energy and sustainability, there is much emphasis on biomass energy around the world which generates an immense volume of residues yearly. These residues are burgeoning issues because they are not effectively managed and utilized. Hence, one solution is utilizing them in the pavement industry. This article focuses on palm oil mill residues that are abundantly available and discarded in Malaysia. This study evaluates published works of literature relating to the utilization of these residues like the Palm Oil Fiber (POF), Palm Oil Fuel Ash (POFA), and Palm Oil Clinker (POC) and Palm Kernel Shell (PKS) in the pavement industry. The outcome of the review acknowledges the greater sustainability potential of these residues with affirmative and satisfactory performance via the result of numerous research work. Also, with a reduction in CO2-emission, low radioactivity, and heavy metal leaching level. Therefore, the review suggests more exploration and utilization of the residue in the pavement industry since it promotes safety and harness sustainability.

Mechanical and structural performance evaluation of pervious interlocking paver blocks

Pervious concrete is one among the evolving sustainable pavement materials due to its unique storm water storage and ground water recharge applications. The present study aims to develop a Pervious Interlocking Paver Block (PIPB) and to study its mechanical, functional and structural performance. In the current explorative research work, the influence of aggregate gradation, and the percentage of fines on mechanical, functional and structural performance of PIPB were evaluated. The mechanical and functional properties such as compressive strength, split tensile strength, flexural strength, and skid resistance are assessed. The structural behaviour of the PIPB pavement section is found using plate load test and large-scale direct shear test. FEM based software, PLAXIS, is used to validate the test results. Infiltration test is conducted on the plate load test section to understand the infiltration rate. Finally, 2D image processing was performed using MATLAB to conclude the test findings. The test results proved that the grade III mix possesses desirable mechanical properties, lower deflection, higher shear strength, and required permeability. The present study affirms that the PIPB can be an effective pavement material for the low volume roads, urban heat island and pavements with drainage problems.

Comparative Study on Asphalt Mixture with Nano Materials and Polymer

Pavement materials are crucial factors affecting pavement durability. Now-a-days, there is dire necessity for roads which are more stable and stronger. Due to weathering conditions and heavy traffic, the pavement surfaces are getting deteriorated by rutting, pot holes etc. Among them asphalt is the most sustainable pavement material for construction pavements and can be used for many applications including highways, airport runways, parking lots and drive ways. In order to provide effective durability than that of asphalt, in its original form it has been modified using Nano-materials known as modified asphalt. In this paper we are gone deal with the advances in Nano-materials in hot mix asphalt and also addition of recronfibre and the comparison was made. With the addition of this Recronfibre, there is an improvement in the properties of bitumen like increase in stability value and decrease in the flow value, % of air voids etc. Recronfibre is an artificial material obtained from the polyester and which is also used as a secondary reinforcement for attaining tensile strength. It helps to resist the cracks obtained by the improper laying of pavement surface and heavy loaded vehicles. But whereas, the clay Nano-particles are the primary materials applying in asphalt construction adding Nano-particles like Nano clay, Nano silica and nanotubes in asphalts normally increase the viscosity of asphalt binders and improves the rutting and fatigue resistance of asphalt mixtures. From this the performance of asphalt when treated with Nano-particles and its sustainability compared to that of other pavement materials is examined and studied.

Characteristics of Polymer Modified Reclaimed Bitumen and Aggregate as a Sustainable Pavement Material

Infrastructure development in a country depends on the development of road network. In a developing country like India construction of pavements forms the integral part of infrastructure development. The most common material used for the construction of pavements is hot mix asphalt (HMA). The demand for this material is very high and at the same time due to maintenance of pavements lot of used paving material is wasted. This paper deals with the characteristics of reusing the reclaimed materials as construction materials in the construction of pavements. Experimental investigations were conducted to study the properties of aggregate and bitumen that are reclaimed. The test results on the reclaimed material were conducted and it was found to be suitable to be reused for the pavement construction. Systematic proportioning of the reclaimed material with the virgin material was investigated and the results show that the reclaimed materials performed equally well as the virgin material. The cost analysis for using these recycled materials is also calculated, in order to highlight the advantage of using the recycled material.

Influence of aggregate size and notch depth ratio on fracture performance of steel slag pervious concrete

Steel slag pervious concrete (SSPC) is a promising sustainable pavement material for sponge city construction. The influence of aggregate size and notch depth ratio on fracture performance of SSPC was studied in this work. Considering two kinds of aggregate size (4–6 mm and 10–20 mm) and four kinds of notch depth ratio (0.2, 0.3, 0.4, 0.5), the three-point bending test of a rectangular beam with a single side notch was carried out, and the whole fracture process was monitored by acoustic emission. The experimental results show that the fracture behavior of SSPC has obvious boundary effect. Meanwhile, large-size aggregates can improve the fracture strength and fracture energy of SSPC, which is related to the stronger mechanical interlocking and bonding between aggregates caused by thicker slurry layer on the surface of large-size aggregates. In addition, the acoustic emission monitoring results show that the internal wave source activity and strength are higher in the fracture process of large-size aggregate specimens, and there are more shear cracks. Finally, the PFC3D numerical model established by the discrete element theory was used to simulate the fracture behavior of SSPC. The results show that the particle flow code is an effective method to study the fracture behavior of pervious concrete.

Molecular structure change and anti-aging performance of WFO-CR composite modified asphalts

In order to use the solid and liquid waste resources to improve performances of base asphalt, waste frying oil (WFO) and crumb rubber (CR) are used to modify the asphalt to obtain the sustainable pavement material. The molecular structures and the performances of the modified asphalts with different amounts of WFO and CR are analyzed by conventional asphalt methods, short-term aging test and Fourier transform infrared spectroscopy (FT-IR). The results indicate that the retained penetration ratio (RPR), the softening point increment (SPI) and retained ductility ratio (RDR) indexes of modified asphalts with different amounts of WFO-CR composite are better than those of the base asphalt after short-term aging test. WFO and CR can improve anti-aging performance. Moreover, FT-IR results show that the absorption peaks at 814 cm^-1 and 720 cm^-1, which represent the alkenyl or benzene ring CC in WFO-CR composite modified asphalt after short-term aging, increase obviously. Both the carbonyl absorption peak and the sulfoxide absorption peak are improved for modified asphalts with different amounts of WFO-CR composite. The quantitative analysis shows that the carbonyl and sulfoxide indices of the modified asphalt reach the lowest values with 5.0% WFO and 20.0% CR, which are 36.02% and 32.04% lower than those of the base asphalt, respectively.