Search Results (23)

Porous asphalt mixtures play a pivotal role in enhancing pavement drainage capacity and traffic safety, where the performance of asphalt binder constitutes a determining factor. This study introduces an innovative advancement through the development of a high-viscoelastic modifier and corresponding modified asphalt based on SBS-modified asphalt, coupled with optimized preparation protocols. The optimal composition and dosage of the modifier were systematically determined through standardized tests including penetration, ductility, softening point, and bending beam rheometer (BBR) analysis. A comprehensive evaluation of road performance was conducted on two porous asphalt mixtures, namely conventional SBS-modified asphalt versus the novel high-viscoelastic modified asphalt (designated as 10-A). Experimental protocols encompassed high-temperature rutting resistance tests, low-temperature beam bending tests, freeze–thaw splitting tests, two-point bending fatigue tests, accelerated abrasion tests, and dynamic friction tester (DFT) measurements. The results demonstrate that the 10-A-modified mixture exhibits superior high- and low-temperature performance. Notably, its fatigue resistance and skid resistance showed minimal divergence from conventional SBS-modified asphalt, attributable to physicochemical crosslinking interactions among antioxidants, resins, and stabilizers. This research elucidates the synergistic mechanism of components within the 10-A modifier system. The proposed high-viscoelastic asphalt formulation meets the technical requirements for functional drainage asphalt mixtures while providing material-level support for implementing sponge city initiatives. Full article

Porous asphalt pavements and water-retentive asphalt pavements are widely used because of their ability to infiltrate both rainfall and stormwater runoff. There is very limited information available to assist designers of porous asphalt pavement systems to be installed on sloping sub-catchments. This is because the infiltration performance of these systems has only been investigated experimentally for horizontal pavements, and their performance on sloping terrains has only been investigated theoretically. This experimental study investigates the relationship between rainfall intensity, pavement slope, runoff and infiltration rates for dense-graded asphalt, porous asphalt and water-retentive asphalt concrete pavements. Three rates of simulated rainfall were applied to porous, water-retentive and dense-graded asphalt specimens set at three different pavement slopes, namely 0°, 3° and 5°. The relationship between the porosity and permeability of the porous asphalt pavements was also determined. A porosity of 20% resulted in a permeability of greater than 1 mm/s. It was found that the porous asphalt specimens had excellent runoff retention and infiltration rates at all slopes. The water-retentive asphalt specimens also produced good infiltration rates at horizontal slopes, but these decreased at higher pavement slopes. Full article

Porous asphalt (PA) mixtures have become a common and very useful pavement technology for preventing dangerous driving conditions in wet weather and as a permeable surface in permeable pavement systems due to their capacity to filter water. The increased social awareness of sustainability matters has expanded the interest in reducing the impact of construction materials on the environment, mainly by using recycled materials in their composition and, hence, reducing the depletion of raw materials. In this research, two innovative recycled filler materials, namely, cellulose ash (CA) and combustion soot (CS), have been used as a total filler replacement in PA mixtures to look for improved mechanical strengths and characteristics. Four different filler dosages were assessed for each filler material, and the produced PA mixtures were tested for their particle loss, water sensitivity, freeze–thaw durability, Marshall stability, resilient modulus and permeability in order to obtain a full picture of their performance. The obtained results showed that both filler materials, adequately dosed, can generate PA mixtures that significantly overcome reference mechanical values for PA mixtures that maintain adequate infiltration capacities to satisfy the main international standards, proving to be suitable replacements for conventional filler materials commonly used in asphalt mixture production. Full article

Rice husk biochar (RHB) is a renewable agricultural waste, and its fixation on pavements helps develop environmentally friendly, economical, and sustainable asphalt pavements. This paper used RHB to replace part of styrene-butadiene-styrene (SBS) for the composite modification study of matrix asphalt. The high- and low-temperature properties and microscopic mechanisms of the composite-modified asphalt were studied through a series of tests. The results showed that, compared with SBS-modified asphalt, the softening point, viscosity, complex shear modulus, stiffness modulus, and rutting factors of RHB-SBS composite-modified asphalt were improved. In contrast, the ductility and creep rate were slightly decreased, indicating an improvement in the high-temperature performance of composite-modified asphalt, but a slight decrease in its low-temperature performance. The process of RHB and SBS composite modification was mainly physical blending, with only a small number of chemical reactions, and no new functional groups were generated. The porous structure of RHB enables it to adhere better to the network crosslinked continuous phase system formed by SBS and matrix asphalt. This results in composite-modified asphalt with good high-temperature storage stability and rheological properties. Therefore, RHB-SBS composite-modified asphalt can be applied to high-temperature areas and rice-producing areas, and the optimal content of RHB is suggested to be 15%. Full article

Moisture is a significant problem in standard pavements, causing asphalt mixtures to deteriorate due to insufficient water permeability. This failure from moisture damage is often caused by precipitation accumulation or poor drainage, which allows water to weaken adhesion by seeping between the aggregates and the asphalt. The relationship between permeability and aggregate contact length is believed to be inverse. To effectively assess water permeability performance and moisture damage, an asphalt concrete design criterion was established using the Image Processing and Analysis System (IPAS) to determine aggregate contact lengths. The objective of this research was to use laboratory experiments in conjunction with IPAS to investigate air-void-controlled asphalt mixtures with various material properties and assess the correlation of water permeability with other factors. The results show that AC60/70, AC60/70+Carbon Black, and AC60/70+SBS combinations with coconut peat filler had the lowest permeability coefficient (k) among similar mixtures, with values of 0.056 × 10⁻⁵ cm/s, 0.010 × 10⁻⁵ cm/s, and 1.508 × 10⁻⁵ cm/s, respectively. Both the dense and porous gradations of the modified asphalt binder demonstrated positive linear relationships between TSR and permeability. This study found a strong linear relationship between TSR (tensile strength ratio) and k (permeability coefficient) in both dense and porous modified asphalt binder gradations, with R² values of 0.79 and 0.74, respectively. Additionally, we found that the number of contact points and contact length in the skeleton strongly influenced the mixes’ permeability, with a linear trend of 0.93 for both indices. Full article

Controlling environmental noise and reducing excessive noise is necessary to protect human health and provide auditory comfort. People are frequently exposed to traffic noise in their daily life and traffic noise is a considerable problem on the city scale. This study investigates the sound absorption coefficient in asphalt pavements so as to reduce traffic and environmental noise. The important parameters affecting the sound absorption coefficient in asphalt pavement, such as the use of porous asphalt pavements, clogging pores, the mixture content change, the thickness change, and getting wet, were identified. It is stated that the sound absorption coefficient in the asphalt layer can be increased with the use of a porous asphalt layer, and by changing the thickness and mixture content. In addition, with the effects of global warming, water supply problems are observable in cities. In this context, the use of rainwater is of vital importance. Permeability of the asphalt layer and storage of rainwater in the lower layer are recommended. The accumulation of rainwater with the aid of drainage in porous asphalt pavements has been investigated and the use of rainwater within the scope of recycling is explored. Within the scope of the research, the construction of porous asphalt pavements is suggested in a system that can store water, reuse rainwater with a new system proposal, and reduce environmental noise by increasing sound absorption performance. Accordingly, it will be possible to reduce the environmental noise level and to use rainwater within the scope of recycling. According to varying thicknesses, porous asphalt pavements were modeled using the finite element method, and the Von Mises stress and vertical deformation results of different thicknesses were compared. Full article

This study proposes the technology of “runoff storage and seepage utilization” for achieving purification of road rainfall–runoff and presents a multi-level series purification system (PBT-GR) comprising porous asphalt pavement (PAP), a bioretention system (BS), a storage tank (T) and a hydroponic green roof (GR). The operation parameters of each component unit were optimized and the contribution of each unit to pollution was analyzed. The results showed that under typical simulated rainfall, the suspended solids (SS), total nitrogen (TN), total phosphorus (TP), Pb, Zn and Cu removal rates by filtration and interception of porous pavement were 62.26 ± 3.19%, 16.29 ± 1.74%, 29.27 ± 1.37%, 37.61 ± 2.58%, 35.57 ± 4.64% and 31.17 ± 3.27%, respectively. The average concentrations of SS, TN, TP, Pb, Zn and Cu in the effluent of the PBT-GR system were 14.70 ± 2.21 mg/L, 1.52 ± 0.24 mg/L, 0.14 ± 0.04 mg/L, 0.09 ± 0.04 mg/L, 0.11 ± 0.03 mg/L and 0.04 ± 0.01mg/L, respectively, which met the water quality standards recommended in the Chinese guidelines and showed a high adaptability to pollution load. The contents of pesticide residues and heavy metals in cultivated vegetables met the national standards. The period required to recoup the investment in the system was approximately 3 years, indicating its good economic feasibility. The present study can provide a valuable reference of the construction of an efficient, low consumption and sustainable urban stormwater treatment system and can contribute to the improvement in the quality of the urban water environment. Full article

Floods are becoming more frequent, especially in urban environments where most of the surface is waterproofed. Permeable pavement (PP) can be applied as low impact development (LID) systems for runoff mitigation in urban areas. Their effectiveness can be assessed, case by case, by numerical simulations. In this study, the effectiveness of mitigating runoff of different permeable pavements has been evaluated. In particular, porous asphalt (PA), pervious concrete (PC), permeable interlocking concrete pavement (PICP) and grid pavement (GP) have been investigated using EPA Storm Water Management Model (SWMM) software. To this aim, a car parking area located in the University Campus of Palermo (Italy) has been taken as a case study, considering several scenarios, each having a different percentage and planimetric layout of a PP type combined with an impermeable pavement. All the scenarios were tested assuming four synthetic rainfall events, referring to return periods of 5, 10, 50 and 100 years, and a real high return period event that occurred in Palermo in 2020. The results showed that amongst the different PPs considered, only the PA, bounded at the bottom by an impermeable layer, was practically ineffective. The other three PPs, proved to be effective in a noticeable way and furthermore for each scenario studied, they proved to bear almost the same mitigated runoff. The results proved appreciable differences in runoff as a function of the location of the PP over the study area. Full article

Porous asphalt pavement (PAP) system is a widely used treatment measure in sustainable stormwater management and groundwater recharge, but their variable performance in nitrogen (N) and phosphorus (P) removal requires further reinforcement prior to widespread uptake. Two laboratory-scale PAP systems were developed by comparing limestone bedding and zeolite incorporated into modified zeolite powder porous microsphere (MZP-PM) as a filter column under a typical rainfall. The PAP system of zeolite bedding incorporated into MZP-PM (a weight less than 5% of zeolite) removed 74.5% to 90.6% of ammonium (NH₄⁺-N) and 72.9% to 92.4% of total phosphate (TP) from the influent, as compared with 25.7% to 62.7% of NH₄⁺-N and 32.6% to 56.4% of TP by that of the limestone as bed material. This improvement was presumably due to MZP-PM’s high adsorption capacity and surface complexation. The formation of ≡(La)(OH)PO₂ was verified to be the dominant pathway for selective phosphate adsorption by MZP-PM and ion-exchange was proved to be the main removal process for ammonium. This study provides promising results for improving N and P removal by modifying a porous asphalt pavement system to include an MZP-PM adsorbent column as a post-treatment. Full article

Self-healing asphalt, which is designed to achieve autonomic damage repair in asphalt pavement, offers a great life-extension prospect and therefore not only reduces pavement maintenance costs but also saves energy and reduces CO₂ emissions. The combined asphalt self-healing system, incorporating both encapsulated rejuvenator and induction heating, can heal cracks with melted binder and aged binder rejuvenation, and the synergistic effect of the two technologies shows significant advantages in healing efficiency over the single self-healing method. This study explores the fatigue life extension prospect of the combined healing system in porous asphalt. To this aim, porous asphalt (PA) test specimens with various healing systems were prepared, including: (i) the capsule healing system, (ii) the induction healing system, (iii) the combined healing system and (iv) a reference system (without extrinsic healing). The fatigue properties of the PA samples were characterized by an indirect tensile fatigue test and a four-point bending fatigue test. Additionally, a 24-h rest period was designed to activate the built-in self-healing system(s) in the PA. Finally, a damaging and healing programme was employed to evaluate the fatigue damage healing efficiency of these systems. The results indicate that all these self-healing systems can extend the fatigue life of porous asphalt, while in the combined healing system, the gradual healing effect of the released rejuvenator from the capsules may contribute to a better induction healing effect in the damaging and healing cycles. Full article

Porous asphalt pavement is a part of the permeable pavement system, which can be used to mitigate the negative impacts of urbanisation on the water hydrological cycle and environment. This study aims to assess the mechanical and hydrologic characteristics of porous asphalt pavements, with and without geocell composites, using a plate load test, falling weight deflectometer test, and rainfall simulation test. The corresponding results indicate that the elastic modulus of the unreinforced pavement is lower than that of the reinforced pavement. The analysis demonstrates that the use of geocell composites effectively increases the load-bearing capacity of the pavement. When the base layer is reinforced with geocells, its load-bearing capacity increases. Observation of the rainfall simulation tests on the reinforced pavement indicates that the reinforced pavement effectively handles the surface runoff. Full article

Permeable pavement has the potential to be an effective tool in managing stormwater runoff through retention of sediment and other contaminants associated with urban development. The infiltration capacity of permeable pavement declines as more sediment is captured, thereby reducing its ability to treat runoff. Regular restorative maintenance practices can alleviate this issue and prolong the useful life and benefits of the system. Maintenance practices used to restore the infiltration capacity of permeable pavement were evaluated on three surfaces: Permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA). Each of the three test plots received a similar volume of runoff and sediment load from an adjacent, impervious asphalt parking lot. Six different maintenance practices were evaluated over a four-year period: Hand-held pressure washer and vacuum, leaf blower and push broom, vacuum-assisted street cleaner, manual disturbance of PICP aggregate, pressure washing and vacuuming, and compressed air and vacuuming. Of the six practices tested, five were completed on PICP, four on PC, and two on PA. Nearly all forms of maintenance resulted in increased average surface infiltration rates. Increases ranged from 94% to 1703% for PICP, 5% to 169% for PC, and 16% to 40% for PA. Disruption of the aggregate between the joints of PICP, whether by simple hand tools or sophisticated machinery, resulted in significant (p ≤ 0.05) gains in infiltration capacity. Sediment penetrated into the solid matrix of the PC and PA, making maintenance practices using a high-pressure wash followed by high-suction vacuum the most effective for these permeable pavement types. In all instances, when the same maintenance practice was done on multiple surfaces, PICP showed the greatest recovery in infiltration capacity. Full article

Stiffness is an important mechanical characteristic of asphalt mixtures used in the wearing course. It is one of the determining factors in the generation of tyre/road noise. The dynamic stiffness of the upper layer of the road surface depends on the physical and mechanical properties of the materials it is composed of, and traffic load. Determination of dynamic stiffness, both in laboratory conditions and in situ, requires consideration of many other factors. Tests of dynamic properties of road surfaces in field conditions are most often conducted with the help of modal hammers. Impulse excitation results are usually less accurate than those in the application of modal exciters. The test stand was constructed, comprising a tripod, 32-channel and 24-bit data acquisition system, exciter, signal amplifier, impedance head, single-axis piezoelectric accelerometers and a stinger. The test stand and the proposed method of measuring dynamic stiffness do not require the determination of the resonance frequency of the tested specimen and can be used both on various types of bituminous mixtures of varying shape and dimensions, as well as directly on the upper surface of the wearing course of bituminous pavements. The test results showed that the type of bituminous mixture used in the wearing course significantly affects its dynamic stiffness. The dynamic stiffness level of asphalt concrete, stone mastic asphalt and porous asphalt layers was determined to be similar. The addition of rubber granulates significantly reduced its rigidity, which is very beneficial from the point of view of reducing the tyre/road noise. Full article

Despite the numerous benefits for preserving the hydrological cycle, permeable pavement systems (PPSs) found their major application in parking spots and for light traffic scenarios due to their limited durability and strength. To make the PPSs suitable for heavy traffic conditions without significant distresses, research is shifting toward the adoption of novel binders and additives for designing multifunctional porous asphalt mixtures which make up the surface course of PPSs. Certain additives are well known for enhancing the durability of dense graded asphalt mixtures and improving fatigue and rutting resistance. However, the studies on the influence of additives on abrasion resistance and binder draindown, which are the common problems in porous asphalt mixtures (PAMs), are still not well established. This paper summarizes best practices performed on PAMs and recommends possible future research directions for its improvement. Particular emphasis is placed on strength and resilience of PAMs by incorporating additives like nanosilica, crumb rubber, warm-mix additives, fibers (such as cellulose, glass, steel, and synthetic fibers), and some eco-friendly materials. It was found that different additives seem to have different effects on the properties of PAMs. Moreover, the combination of additives has synergistic benefits for the performance of PAMs, especially in urban pavements. Full article

Porous Asphalt (PA) pavements are an increasingly adopted tool in the green stormwater infrastructure toolbox to manage stormwater in urbanized watersheds across the United States. This technology has seen particular interest in western Washington State, where permeable pavements are recognized as an approved best management practice per the National Pollutant Discharge Elimination System (NPDES) municipal stormwater permit. Stormwater effluent concentrations from six PA cells were compared with runoff concentrations from three standard impervious asphalt cells to quantify pollutant removal efficiencies by porous asphalt systems. Additionally, the effects of maintenance and pavement age on pollutant removal efficiencies were examined. Twelve natural and artificial storms were examined over a five-year period. Street dirt and pollutant spikes were added to the pavements prior to some storm events to simulate high loading conditions. Results from this work show that porous asphalt pavements are highly efficient at removing particulate pollutants, specifically coarse sediments (98.7%), total Pb ( 98.4%), total Zn (97.8%), and total suspended solids (93.4%). Dissolved metals and Polycyclic Aromatic Hydrocarbons (PAH) were not significantly removed. Removal efficiencies for total Pb, total Zn, motor oil, and diesel H. improved with the age of the system. Annual maintenance of the pavements with a regenerative air street sweeper did not yield significant pollutant removal efficiency differences between maintained and unmaintained PA cells. Full article