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Permeable asphalt pavement (PAP) has many advantages such as reducing surface runoff and improving driving safety on rainy days; hence, it has attracted much attention from researchers. PAP is greatly affected by environmental fac...
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Permeable asphalt pavement (PAP) has many advantages such as reducing surface runoff and improving driving safety on rainy days; hence, it has attracted much attention from researchers. PAP is greatly affected by environmental factors due to its porous structure and the temperature characteristics are different from those of dense asphalt pavement (DAP). This study aims to understand the influences of environmental conditions on the patterns of temperature distribution in PAP and DAP. Weather station and temperature sensors were installed while paving PAP and DAP. Meteorological data and temperature data of each structural layer of PAP and DAP were collected during 2019-2021. The results demonstrate that temperatures in the depth range of 4 similar to 10 cm below the PAP surface were 1 similar to 6 & DEG;C higher than DAP on rainless days. The heat storage and dissipation efficiency of PAP within the depth range of 4 similar to 40 cm were better than that of DAP. The maximum influence depth of PAP that heavy rainfall can affect is 60 cm, the maximum cooling extent of PAP is 5 similar to 6 & DEG;C, and the minimum cooling duration of PAP is 10 h on rainy days. This study provides a reliable foundation for evaluating the extent of the environmental impacts of PAP.
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While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are li...
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While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m~2, lined sections that direct all infiltrate into 5.7-m~3 tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP and PC, and this was attributed to the high pH in PA infiltrate possibly causing rapid precipitation of orthophosphate with metal cations. Orthophosphate was exported from the PICP and PC, as evidenced by the significantly larger infiltrate concentrations compared with influent sources of rainwater and runoff.
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Results are presented for the intrinsic permeability and form drag coefficient (C_F) for a set of nominally identical cylindrical pervious concrete specimens. Specimens were tested at a range of flow rates in a constant head perme...
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Results are presented for the intrinsic permeability and form drag coefficient (C_F) for a set of nominally identical cylindrical pervious concrete specimens. Specimens were tested at a range of flow rates in a constant head permeameter. The mean and standard deviation of the permeability and C_F show substantial variability. This statistical characterization of hydraulic performance was used to model the behavior that would be observed using other standard methods for characterizing hydraulic performance of porous pavement mixtures. Results indicate that falling head, constant head, and infiltration tests have the potential to significantly underestimate the permeability of porous pavement mixtures. Results from modeled falling head tests showed that this test results in permeability estimates up to a factor of ten lower than the actual permeability and are uncorrelated to the actual permeability. For high permeability pavement mixtures, falling head tests will only provide adequate values of permeability if run at heads so low that measurement resolution is a problem. Constant head tests can be used, though model results indicate that, even for very small hydraulic gradients, the head versus flow rate relationship is quadratic. As such, C_F must be calculated. Failure to do so leads to significant underestimation of the permeability. For most applications, the permeability of a well-designed and placed pervious concrete is more than adequate and the improvement in accuracy gained by fully characterizing both the permeability and C_Fof a pavement is not necessary. However, for poorly constructed pavements, or pavements that need to infiltrate large amounts of run-on from adjacent impervious areas, the additional accuracy may be important. The additional level of accuracy is also important for research into improving design and construction of pervious concrete where comprehensive and accurate characterization of test specimens is needed for statistically significant comparisons between different design specimens.
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The clogging of the void spaces within the permeable base by foreign particles can severely reduce its drainage capacity. This will, in turn, reduce the service life of the permeable base layer within the pavement. In this paper, ...
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The clogging of the void spaces within the permeable base by foreign particles can severely reduce its drainage capacity. This will, in turn, reduce the service life of the permeable base layer within the pavement. In this paper, the reduction in the vertical permeability of several permeable base mixes as a result of clogging has been studied. The clogging materials used are mixtures of sand and residual soil. An empirical theoretical formulation has been derived from the Kozeny-Carmen equation in order to predict the reduction in permeability of the permeable bases. The equation has been expressed in terms of the initial vertical permeability of the permeable base specimen, porosity, amount of clogging material retained, and an experimental empirical coefficient. This coefficient is found to be dependent on the ratio of the D_(15) size of the permeable base to the d_(85) size of the clogging material and coefficient of uniformity, C_u, of the clogging material. The theoretical predictions have been compared with experimental results, with good agreement.
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Permeable pavements mitigate the impacts of urbanization on surface waters through pollutant load reduction, both by sequestration of pollutants and stormwater volume reduction through exfiltration. This study examined the non-win...
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Permeable pavements mitigate the impacts of urbanization on surface waters through pollutant load reduction, both by sequestration of pollutants and stormwater volume reduction through exfiltration. This study examined the non-winter water quality performance of two side-by-side permeable pavements in the Ohio snowbelt. The permeable interlocking concrete pavements were designed to drain impervious catchments 2.2 (large) and 7.2 (small) times larger than their surface area, were located over clay soils, and incorporated the internal water storage design feature. Nutrient reduction was similar to past studies-organic nitrogen and particulate phosphorus were removed through filtration and settling, while dissolved constituents received little treatment. Because of 16 and 32 % volume reductions in the small and large installations, respectively, nutrient loads were often significantly reduced but generally by less than 50 %. Aluminum, calcium, iron, magnesium, lead, chloride, and total suspended solids (TSS) concentrations and loads often increased after passing through the permeable pavements; effluent TSS loads were three-to five-fold higher than influent TSS loads. This was apparently due to seasonal release of clay-and silt-sized particles from the soils underlying the permeable pavement and inversely related to elapsed time since winter. The application of de-icing salt is thought to have caused deflocculation of the underlying soils, allowing particulates to exit with stormwater as it discharged from the underdrain of the permeable pavements. By autumn, both permeable pavements discharged metals and TSS concentrations similar to others in the literature, suggesting the de-icing effects lasted 3-6 months post-winter. Sodium may substantially affect the performance of permeable pavements following winter de-icing salt application, particularly when 2: 1 clay minerals, such as vermiculites and smectites, predominate.
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Pervious concrete (PC) is used for parking lots and streets that are subjected to repeated wheel loading, therefore it is necessary to characterize the fatigue life (N) of PC for pavement design. This research investigates the beh...
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Pervious concrete (PC) is used for parking lots and streets that are subjected to repeated wheel loading, therefore it is necessary to characterize the fatigue life (N) of PC for pavement design. This research investigates the behavior of PC beams made with two aggregates (angular and round) and three porosity levels (20%, 25% and 30%) under flexural fatigue loading in three stress ratios (SR:) 0.75, 0.8, and 0.85. The results showed that N is controlled by SR, while porosity showed no statistically significant effect on flexural fatigue. Two-parameter Weibull distribution was fitted to the test data to generate fatigue models at different reliability levels. Using the existing model for portland cement concrete (PCC) for PC results in an overestimation of N for SR > 0.75 due to the highly porous and brittle macrostructure of PC. Existing PCC model agrees with the proposed PC model in predicting N at 0.5 < SR < 0.75, while overestimates N at SR < 0.5. The proposed fatigue model can be used in the thickness design of PC pavements. (C) 2019 Elsevier Ltd. All rights reserved.
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Planting of street trees in cities and other high-density urban environments can provide significant social, economic and environmental benefits. However, street trees in pavements can often lead to shallow root growth resulting i...
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Planting of street trees in cities and other high-density urban environments can provide significant social, economic and environmental benefits. However, street trees in pavements can often lead to shallow root growth resulting in damage to pavements, kerbs, roads and buried services. This study investigated whether pavement damage by tree roots could be reduced by planting trees in a permeable pavement system with an underlying layer of 20 mm diameter gravel to direct tree roots deeper into the pavement structure. A six-year duration field experiment was conducted to compare the growth of trees and their root systems in a conventional impermeable pavement with growth in a series of permeable pavements with different depths of underlying gravel basecourse. The results demonstrated that permeable pavements with underlying gravel layers encouraged tree roots to travel deeper into the underlying subgrade soil, thereby reducing costly pavement damage. This effect was more pronounced with deeper rather than shallower basecourse layers. While permeable pavements affected tree root growth, they had no significant influence on tree height after six years' growth. (C) 2019 Elsevier B.V. All rights reserved.
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Impermeable pavements in high-density cities are one of the main causes of the aggravation of the Urban Heat Islands (UHI) phenomenon. The transformation of impermeable pavements into cool pavements constitutes a promising and inn...
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Impermeable pavements in high-density cities are one of the main causes of the aggravation of the Urban Heat Islands (UHI) phenomenon. The transformation of impermeable pavements into cool pavements constitutes a promising and innovative technique for the mitigation of UHIs. This review paper treats the technique of cool pavements or evaporative pavements, firstly on the basis of the energy balance that occurs on the surface of such pavements, in the aim of identifying the different approaches that can be adopted to enhance the technique employed. Then, this work will place particular emphasis on the various factors and properties that help to optimize this technique, as well as on the effect that incorporating certain materials has on the properties mentioned, in order to expand perceptions in the design of cool pavements. The paper ends with the main criteria for durability of cooling pavements and the corresponding maintenance techniques.
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In this study, a novel backwashing maintenance method for permeable concrete pavements (PCP) was developed, and its performance was evaluated via a 2-year field comparative study at two PCP sites. Results showed that regular maint...
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In this study, a novel backwashing maintenance method for permeable concrete pavements (PCP) was developed, and its performance was evaluated via a 2-year field comparative study at two PCP sites. Results showed that regular maintenance can mitigate clogging and extend the service life of PCPs. After 2 years of regular maintenance via hand sweeping, vacuuming, pressure washing, vacuuming followed by pressure washing, and the proposed novel backwashing maintenance method presented in this study, the average surface infiltration rates (SIRs) at the maintenance points (testing locations) were 1.3-fold, 1.3-fold, 1.7-fold, 1.8-fold, and 2.1-fold those of the corresponding control points at the mildly clogged PCP Site 1, and 2.1-fold, 3.5-fold, 6.1-fold, 14.0-fold, and 18.1-fold those of the corresponding maintenance points at the heavily clogged PCP Site 2, respectively. The proposed novel backwashing maintenance method outperformed conventional maintenance methods, but its recovery rate depended on the clogging conditions and the backwashing pore flow velocity in the PCP layer. Further studies are needed to promote the wide application of this novel backwashing maintenance method and prolong the service life of PCPs.
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The hydrologic performance of three partial-infiltration permeable pavement (PP) systems was evaluated at the Kortright Centre for Conservation in Vaughan, Ontario, Canada over 22 months. Partial-infiltration systems allow some st...
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The hydrologic performance of three partial-infiltration permeable pavement (PP) systems was evaluated at the Kortright Centre for Conservation in Vaughan, Ontario, Canada over 22 months. Partial-infiltration systems allow some stormwater to infiltrate into native soils and drain excess water by way of underdrains. The native soils at Kortright are composed of clayey silt and silty clay till, with clay content ranging from 7 to 30%. Flow restrictors on the underdrains were adjusted to the smallest orifice possible to assess the potential for stormwater outflow volume reductions. The hydraulic behavior of the PP systems was compared with runoff from an asphalt parking lot control. Peak outflow rates from PP were 91% smaller than peak flowrates of asphalt runoff on average, and attenuation of stormwater was observed during all seasons. Stormwater was found to infiltrate at the surface of the PP systems throughout two winters. Although increases in outflow were observed during periods of seasonal thawing due to the delayed release of infiltrating stormwater, the PP systems (with restricted flows from the underdrains) reduced overall stormwater outflow volume by 43% and completely captured (i.e., infiltrated and evaporated) most rainfall events that were less than 7 mm in depth. The study demonstrated that in cold climates and over low permeability soils, partial-infiltration permeable pavements reduce the volume, peak flow, and frequency of storm flows. These changes to the hydrology of stormwater are important for achieving water quality benefits as well as sustaining a more natural water balance and flow regime.
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