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Skid resistance of pervious concrete (PC) in comparison with traditional portland cement concrete (PCC) was investigated in the laboratory and in the field. Dry, wet, and iced PC surfaces were test...

This technical note tests the efficacy of a carbonate-laden water treatment on pervious concrete to increase its resistance to magnesium chloride (MgCl2) attack. A treatment method and an ...

Magnesium chloride deicers applications onto pervious concrete pavements can deteriorate the material, and studies investigate treatments to increase the concrete resistance to MgCl2 attacks. In this paper, pervious concrete specimens are subjected to a treatment with NaHCO3 solution, which seems to accelerate concrete carbonation and might hamper chemical reactions between MgCl2 deicer and hydroxides in cement mortar. All specimens had their compressive strength tested and the time frames before and after treatment varied. Results show that at least 2 months should be given post curing before treatment to not harm the concrete, and longer post treatment periods may be beneficial.

Loratorial tests with pervious concrete comprised porosity and hydraulic conductivity as well as mechanical parameters as compressive, indirect tensile and bending strengths besides assessing its static and dynamic elasticity moduli. Later, a pervious sidewalk area of 1.0 x 8.65 square meters was built in order to determine the variation of the infiltration rate along time; over such experimental sidewalk, impact deflection tests performed allowed to assess back calculated moduli of the pervious concrete layer, resulting 33% to 13% lower than conventional concretes. A mechanistic analysis allowed to estimate the required thickness of concrete for heavy- and light-traffic areas. Tests disclosed no significant difference among the different concrete mixes, with 25% porosity and 0,1 cm/s permeability. Initial sidewalk infiltration rate of 0.5 cm/s dropped 50% four months after construction. It was verified that pervious concrete thicknesses for trucks and buses use are far higher than conventional concrete pavements. Resumo Testes laboratoriais com concreto permeável incluíram medidas de porosidade e condutividade hidráulica, bem como parâmetros mecânicos - resistência à tração, tração indireta e flexão - além de avaliar seus módulos de elasticidade estático e dinâmico. Posteriormente uma área permeável na calçada de 1,0 x 8,65 metros quadrados foi construída para determinar a variação da taxa de infiltração ao longo do tempo; nesse experimento mediram-se deflexões de impacto na calçada, tendo sido avaliados os módulos retroanalisados da camada de concreto permeável, resultando 33% a 13% abaixo dos concretos convencionais. Uma análise mecanicista permitiu estimativa da espessura para o concreto em áreas de tráfego pesado e leve. Os testes apontaram não haver diferenças significativas entre as misturas estudadas, tendo porosidade de 25% permeabilidade de 0,1 cm/s. A taxa de infiltração inicial na calçada de 0.5 cm/s caiu 50% após quatro meses. Verificou-se que são requeridas maiores espessuras de concreto permeáveis que de concretos convencionais para sua aplicação para veículos comerciais.

The pervious concrete layer in a permeable pavement system may be susceptible to chemical degradation by various deicers applied during winter weather events. In this research, the chemica...

Pervious concrete can be utilized simultaneously as a pavement surface and part of a stormwater management system. In cold climates, it may be exposed to deicers, many of which have been sh...

Pervious concrete systems are developing stormwater management technologies which also have wintertime benefits as melting snow may percolate into the system instead of refreezing on the surface. Enhancing the surface microtexture of pervious concrete may also be beneficial in preventing icing or slipping by pedestrians. This research explored different surface treatments on pervious concrete specimens both qualitatively from personal judgements, and quantitatively through static friction measurements with a spring balance with respect to “slipperiness”. The tests were performed on both dry and wet specimens. One aim was to determine whether the spring balance method may be a simple test for comparing surface treatments on pavement samples with little surface area such as laboratory specimens or sidewalk sections. The other purpose was to make a preliminary decision of which surface treatments to use for a sidewalk installation for future studies on wintertime performance. The reliability analysis of the spring balance results showed that there was high operator consistency. In addition, there was a high level of consistency on average results between the quantitative and qualitative methods. This implies that the spring balance test may be an acceptable methodology for comparative analyses with respect to static friction.

Pervious concrete (PC) pavement applications are growing in popularity due to the environmental and stormwater management benefits that PC can offer. However, relatively low mechanical properties and durability of PC, comparing to conventional Portland cement concrete (PCC), limit its use for vehicular applications. In this study, different size fractions of cured carbon fiber composite material (CCFCM) pieces were incorporated into a PC mixture (rPC) in three volume fractions. The goal was to determine the physical and mechanical properties of rPC in comparison to the corresponding properties of plain PC (control). Seven mixture designs were prepared in order to investigate the effect of CCFCM volume fractions as well as CCFCM particle sizes. The test results indicated that CCFCM addition enhanced the workability of the PC mixtures. rPC mixtures presented higher average infiltration rates when compared to the control mixture. Improvements in mechanical properties were seen on 28-day compressive strength (4–11%), 7-day tensile strength (11–46%) and in modulus of elasticity (6–45%). In terms of resistance to mass loss in Cantabro and surface abrasion, rPC mixtures presented various behaviors, with one mixture containing the highest volume fraction and a combined size fraction, outperforming the control in both tests. Overall, the results of this study indicate that incorporation of CCFCM is promising in improving physical and mechanical properties of PC.

A simple design method is proposed to obtain the desired porosity by controlling density and compaction efforts. Then, the w/c ratio and chemical admixture were varied to obtain the desired porosity and to evaluate their influence on the permeability and mechanical performance of pervious concrete. The incorporation of a rheology-modifying admixture showed an improvement in the densification and flowability of the mixture, which can increase the mechanical strength. For the same porosity obtained between mixtures, the decrease in w/c ratio did not influence the compressive strength but was shown to increase flexural tensile strength.

Pervious concrete may be used for stormwater management since it allows the water to pass through its interconnected macropores into stormwater systems or soils below. However, there is a need for additional standards related to pervious concrete prior to its widespread use, and there are many aspects related to mix design for desired properties, compaction methods, and test procedures that are not yet completely understood. These variables may significantly affect the functional and mechanical performance of the material. In this paper, mix designs and test specimen preparation techniques were evaluated. The IBRACON method for mixture design was used to obtain the mixture proportions and the calculated density for the desired porosity of 25%. In addition, two different types of specimens (cast or cored) and compaction methods (roller or Proctor hammer compacted) were performed. The density of each specimen was controlled to obtain the same calculated density. Several tests were conducted to compare the following variables: density, porosity, surface infiltration rate, permeability and compressive strength. Additionally, the effects of mortar capping versus neoprene-rubber caps on compressive strength measurements of pervious concrete were evaluated. The experimental results showed that cast specimens have more consistent results than cores. The design method studied with strict control of density was efficient to obtain the desired porosity mainly for cast specimens. The roller leads to a more compacted top surface resulting in a decrease in the infiltration rate and permeability of the cores. The mortar capping method is more consistent than the other. Resumo O concreto permeável é um material de potencial para ser utilizado no gerenciamento de águas pluviais, uma vez que permite a percolação da água através de seus macroporos interconectados, seja para sistemas de águas pluviais ou para o próprio solo. No entanto, há uma necessidade de normas adicionais relacionadas ao material para seu uso difundido e, ainda, há muitos aspectos relacionados aos parâmetros de dosagem para propriedades desejadas/projetadas, método de compactação e procedimentos laboratoriais, que ainda não foram completamente compreendidos. Tais variáveis podem afetar significativamente o desempenho funcional em termos hidráulicos e mecânicos do material. Neste trabalho, o método do IPT/EPUSP para dosagem foi utilizado para obter as proporções de mistura e a densidade calculada, para uma porosidade desejada de 25%. Além disso, dois tipos diferentes de amostras (moldadas e extraídas) e métodos de compactação (Proctor e rolo) foram realizados. A densidade de cada amostra foi controlada para obter a mesma densidade calculada. Diversos testes foram realizados para comparar as seguintes variáveis: densidade, porosidade, taxa de infiltração, permeabilidade e resistência à compressão. Além disso, foram avaliados os efeitos do tipo de capeamento (com argamassa e com borracha de Neoprene) nos corpos de prova submetidos ao ensaio de compressão. Os resultados experimentais mostram que os corpos de prova moldados apresentam resultados mais consistentes que as amostras extraídas. O método de dosagem, com controle rigoroso da densidade, foi eficiente para obtenção da porosidade desejada, principalmente para os corpos de prova moldados. O rolo conduz a uma superfície superior mais compacta, o que resulta na diminuição da taxa de infiltração e permeabilidade para as amostras extraídas. O capeamento dos corpos de prova com argamassa apresenta resultados mais consistentes.

This study evaluated changes in moisture and temperature of clay soils next to an underground aggregate storage bed of a pervious concrete pavement system during the winter in Pullman, Wash...

Pervious concrete pavement systems may have many environmental benefits including the mitigation of heat island impacts. This mitigation is a complex combination of pervious concrete‟s insulating capability and its ability to store water which may provide evaporative cooling. However, the introduction of water may also bring heat into the system, where the system is the pervious concrete pavement layer over an underground aggregate bed for retention and/or detention of stormwater. This study involved three different mix design placements in southern Brazil on a hot sunny summer day. The experiment had a control section and two test spots where controlled artificial rain events were introduced at two times during the afternoon for each of the three placement types. The „rain‟ initially brought heat from the surface into the pervious concrete layer. Subsequent evaporation cooled these interior pavement layers to levels similar to the control locations. This introduction of water into pervious concrete with very hot surface temperatures in the heat of the day is expected to be a severe condition for adding heat to the system through the flow of water. If water additions are made at different diurnal times, such as nighttime rain, they may provide similar evaporative benefits with less heat transfer into the system via the water phase, and thus even more cooling of the system. These experiments reinforce the conclusion that pervious concrete may be a cool pavement during summer conditions, even under extreme conditions when surface heated stormwater enters the system. Keywords: pervious concrete pavement, stormwater, heat island

Pervious concrete placements in many locations are subject to cold weather conditions and varying levels of clogging and rejuvenation. This study focuses on field surface hydraulic performa...

The increased rate of carbon dioxide sequestration (carbonation) is desired in many primary and secondary life applications of concrete in order to make the life cycle of concrete structures more carbon neutral. Most carbonation rate studies have focused on concrete exposed to air under various conditions. An alternative mechanism for accelerated carbon sequestration in concrete was investigated in this research based on the pH change of waters in contact with pervious concrete which have been submerged in carbonate laden waters. This may be pertinent for applications of concrete reuse in marine or other aqueous applications such as jetties and riprap. The results indicate that the concrete exposed to high levels of carbonate species in water may carbonate faster than when exposed to ambient air, and that the rate is higher with higher concentrations. Validation of increased carbon dioxide sequestration was also performed via thermogravimetric analysis (TGA). It is theorized that the proposed alternative mechanism reduces a limiting rate effect of carbon dioxide dissolution in water in the micro pores of the concrete.

This research investigated whether pervious concrete is effective in removing dissolved zinc and copper contaminants from stormwater runoff. Pervious concrete cylinders were loaded in the laboratory with simulated runoff, and influent and effluent concentrations and volumes measured. In one set of tests, stormwater was dispensed at typical concentrations (100 μg/L Zn and 20 μg/L Cu) simulating ten consecutive storm events of 12 mm (0.5 in.) of rain to test initial removal performance. Another set of cylinders was loaded at forty times the typical concentration to simulate accelerated longterm metal loading indicative of several years of typical use. Cylinders were removed after 15 and 24 accelerated events respectively for further typical concentration performance testing. Performance for the typical concentration tests both pre and post accelerated loading were calculated as a percent metals retained and also as a percent decrease in effluent versus influent concentration. The pre accelerated metal loading results indicate averages of 93% and 91% retained, and 90% and 87% concentration decreases for Zn and Cu respectively. Similar percentages were retained post accelerated metal loadings with slightly lower averages for copper after 24 accelerated loading events, although this was probably due to a higher infiltration rate. Removals were seen to be effected by both physical (water trapping) and by chemical (sorption and complexation) processes.

Pervious concrete has the unique characteristic of allowing water to pass through its porous matrix. . Pervious concrete pavement systems usually have three main layers, pervious co ncrete on the top, a subbase layer of aggregate for water storage in the middle and the subgrade (soil) layer below. Finite element mod eling of this novel material is challenging due to its complex porous characteristics. In this paper, a method has been p roposed to model pervious concrete pavement using f inite element methods, which includes a modified approach to capture the unique vertical porosity distribution in the pervious conc rete layer by averaging the distribution in three distinct vertical sections. The mechanical properties of the pervious concrete l ayer are assumed to vary along its depth since the porosity of the pervious concrete a lso varies with depth. ABAQUS, a general-purpose fi nite element software package was used to develop the model and perform the analy sis. The model was validated through a convergence study, and in comparison with the analytical theory of tensile stress and de flection for traditional concrete pavement. In addi tion, the significance of the porosity distribution model was validated by compar ing the results from EverFE ‐ a specific software f or pavement structure analysis. It was found that there is significant difference itensile stress if modeled using the modified vert ical porosity distribution in the previous concrete layer to more fully capture its v ertical porosity distribution, as compared to an av eraged porosity model in the previous concrete layer. It was also noted that com pressive stress demand may have increased importanc e for pervious concrete, but only for highly porous applications which are not cused.

Widespread adoption and acceptance of pervious concrete systems in new areas using local materials and equipment are dependent on having information on the efficacy of the mix and their longterm needs for rehabilitation. In Porto Alegre, Brazil recent governmental mandates include incorporating permeable pavements into projects. This study expanded on research into the effectiveness of using readily available aggregate for adequate hydraulic performance and clogging resistance of pervious concrete to also determine the effectiveness of maintenance procedures. Laboratory specimens from three mixes with differently screened aggregate were cast and infiltration rates evaluated initially, post clogging, after sweeping and after powerwashing. The results indicate that all three mixes maintain similar hydraulic functionality after rehabilitation, and that powerwashing is more effective in rejuvenating infiltration capabilities than sweeping. In addition, it is recommended to perform infiltration testing twice after maintenance, as there is a slower rate measured on the second test, probably due to dislodged debris re-entering the system during the first test. Similar laboratory methodologies for mix design and maintenance evaluation might effect a faster and more efficient incorporation of this sustainable low impact development technology in other regions.

To expand the applications of pervious concrete, additional research and testing must be conducted as to its structural performance. Distress surveys were performed on two field installations of pervious concrete subjected to equivalent traffic stresses as some collector streets in use for 20 years. The results of the distress survey were then used to calculate the pavement condition index (PCI) using the procedure from ASTM D6433. The PCI rating was considered to be a quantification of structural performance. The high PCI ratings of the thicker pervious concrete sections indicated that pervious concrete, when properly designed, is capable of being used for most residential streets and many collector streets for typical design life durations (20–30 years) while exhibiting satisfactory structural performance.

As the world becomes more urbanized, concerns over the urban heat island (UHI) are more pronounced. Increased urban temperatures have a negative affect on the natural and human environment by producing increased energy usage and smog formation. Pervious concrete pavement is one technology that may help mitigate increased urban temperatures. Temperature data from an instrumented site in Iowa and heat storage phenomena for various weather patterns are presented. The site contains both pervious concrete pavement with a solar reflectance index (SRI) of 14 and traditional concrete pavement with an SRI of 37. Leadership in Energy and Environmental Design (LEED) accepted a high SRI (>29) as one method to characterize a cool surface. Heat capacities of both systems were studied along with a sensitivity analysis of the inputs. The research supports the conclusion that even though pervious concrete may have a much lower SRI than traditional concrete made with similar materials, it can be considered a cool pavement option. In addition, daytime rainfalls combined with the internal high surface area result in significantly more removal of stored heat from the system, with a more rapid mitigation of UHI impacts and reduction in the potential for thermal shock from impervious surface runoff.

Heat and moisture transfers can lead to considerable fluctuations in thermal and moisture related properties in a soil system caused by daily and seasonal temperature changes. Of interest i...

A computerized falling head permeameter system was used to measure hydraulic conductivity of pervious concrete from samples taken from three different field-placed slabs with known porosities. Important differences between samples were found, and these follow the same trend as differences in porosity. The relationship between porosity and hydraulic conductivity is suggested as a tool for designing pervious concrete pavements as a stormwater pollution best management practice. A quantitative relationship between porosity and hydraulic conductivity was established based on the Carman-Kozeny equation for the samples tested. Samples with porosities less than 15% presented limited hydraulic conductivity. Important considerations on the measurement of hydraulic conductivity of pervious concrete samples are discussed, and the Ergun equation is used to explore the flow regime inside pervious concrete samples.

Pervious concrete is an alternative paving surface that can be used to reduce the nonpoint source pollution effects of stormwater runoff from paved surfaces such as roadways and parking lots by allowing some of the rainfall to permeate into the ground below. This infiltration rate may be adversely affected by clogging of the system, particularly clogging or covering by sand in coastal areas. A theoretical relation was developed between the effective permeability of a sand-clogged pervious concrete block, the permeability of sand, and the porosity of the unclogged block. Permeabilities were then measured for Portland cement pervious concrete systems fully covered with extra fine sand in a flume using simulated rainfalls. The experimental results correlated well with the theoretical calculated permeability of the pervious concrete system for pervious concrete systems fully covered on the surface with sand. Two different slopes (2% and 10%) were used. Rainfall rates were simulated for the combination of direct rainfall (passive runoff) and for additional stormwater runoff from adjacent areas (active runoff). A typical pervious concrete block will allow water to pass through at flow rates greater than 0.2 cm/s and a typical extra fine sand will have a permeability of approximately 0.02 cm/s. The limit of the system with complete sand coverage resulted in an effective system permeability of approximately 0.004 cm/s which is similar to the rainfall intensity of a 30 min duration, 100-year frequency event in the southeastern United States. The results obtained are important in designing and evaluating pervious concrete as a paving surface within watershed management systems for controlling the quantity of runoff.

Surface area specific runoff coefficients were measured for nonclogged Portland cement pervious concrete systems according to the rational method. The systems were simulated with pervious concrete blocks with porosities ranging from 16 to 27% placed over sand subbases. Rainfall was simulated in a flume setup with surface slopes ranging from 2 to 10%. There was negligible runoff for typical rainfall events under 100 years frequency in South Carolina. Runoff rates were also simulated for a combination of direct rainfall and additional stormwater runoff from adjacent areas. The results obtained are important for the design of pervious concrete runoff management systems.

Widespread adoption and acceptance of pervious concrete systems are dependent on determining the in situ properties of the placement. The porosity of the pervious concrete layer is the dominant variable of the system, affecting durability, hydraulic, and mechanical properties. Current practice has the porosity of the system estimated prior to placement by a fresh concrete density test on the mix from the concrete mixer, and tested after placement by extracting cores and performing a hardened porosity test. This study provides a method for correlating the surface infiltration rate of a newly placed pervious concrete layer and its estimated porosity with simple linear equations. Although not intended to replace standardized acceptance porosity tests, using this existing nondestructive infiltration method for also estimating porosity may readily provide more information on the variable characteristics of an entire pervious concrete slab for correlation to additional studies, performance, and evaluation of installation techniques. The findings also indicate that the standard 300-mm-diameter single-ring surface infiltration test would have similar results to a more involved double-ring imbedded infiltration test. Finally, the research provides information on interpreting the relationship of laboratory measured infiltration rates for single-lift versus double-lift compaction methods, and shows that coring may have impacts on the surface infiltration rate performed on the extracted cores, probably because of coring debris clogging some of the pores.

Pervious concrete is a unique construction material that serves simultaneously as a structural surface and a stormwater best management practice. Due to its void structure that allows for water and air to flow through the pavement, there are many existing concrete testing methods that may not be readily adapted to account for these differences, and simultaneously there are many procedures for porous material testing that may not be easily adapted to its solid structure. Testing methods for this novel material are needed for many reasons, from research consistency to material acceptance during placement and for determining long-term maintenance needs. This paper will review some of the testing methods currently under development for pervious concrete and summarize research methodologies which are being explored.

This paper will discuss how novel concrete mixtures have been adopted to address many environmental concerns in recent years. One of these is pervious concrete, which is being used to manage stormwater runoff. With large internal surface areas exposed to air, the reactions within pervious concrete may be different from those in traditional concretes. This paper focuses on how hydration in cement pastes varies for thin samples with increased exposure to air. The traditional formation of calcium hydroxide might be altered by competition for the calcium oxide site by carbon dioxide and the lower levels of water within the paste. Thermal programmed desorption (TPD) was used to analyze cement samples under various environmental conditions. It was found that there was a substantial decrease in the formation of calcium hydroxide in the thin samples with high exposure to air as compared to similar samples with restricted exposure.

Pervious concrete is an alternative paving material that may alleviate many of the environmental problems caused by urban runoff from developed areas. Additional research is important so that pervious concrete can be better specified and more effectively used. An important property of pervious concrete is porosity, which will affect the hydrological and strength properties of the material. This research shows that there is a vertical distribution of porosity in slabs placed with certain placement techniques. The vertical variation of porosity can affect the strength distributions within the material and the permeability of the system and its potential for clogging. These studies indicate that for slabs approximately 15 cm (6 in.) in height and placed with an approximately 10% surface compaction technique, the porosity increases significantly from top to bottom. A series of vertical porosity distribution equations have been developed to effectively model this using the percent compaction and average cored porosities.

The modulus of elasticity is an important property for evaluating the mechanistic response of any material under load, and porosity influences the rheological, mechanical, and hydraulic properties of pervious concrete. The relationship between porosity and modulus of elasticity of pervious concrete has not been well researched. In this study, pervious concrete cylinder specimens were prepared for a range of porosities and compression tests were performed to determine the moduli of elasticity. Secant moduli of elasticity at five different stress levels (i.e., 2.2, 2.8, 3.3, 3.9, and 4.4 MPa) were calculated from the load-deformation data of the compression tests. Three performance zones were proposed for estimating the modulus of elasticity based on porosity at the stress levels of 2.2 and 2.8 MPa, i.e., lower, average, and upper. These performance zones provide designers with more information based on the variability and heterogeneous distribution of porosity in a pervious concrete section for risk-based assessments. While more research is required for comprehensive characterization of pervious concrete, the modulus of elasticity equation in the lower performance zone might provide an initial performance assessment of pervious concrete until its components can be better characterized.

Pervious concrete is a paving material that has a number of stormwater and other environmental benefits. Most current applications of pervious concrete are in residential streets, parking lots, driveways, and sidewalks, and it is being considered for shoulders and more high volume applications. Characterizations of stress distribution and deflection patterns in pervious concrete systems may be useful parameters in the structural design of these high volume uses. Pervious concrete panels with tandem axle dual wheel loads were analyzed using finite element analysis. The wheel position was considered in the corner, center, and edge of the pavement. The critical stresses obtained from the analyses were compared against experimental tensile and compressive strengths obtained from samples from a field application for various pervious concrete layer thicknesses, and additional experimental data. It was found that pervious concrete panels of sufficient thickness have adequate strength to support the applied wheel loads. To compare the long term performance when subjected to cyclic loading, the critical tensile stresses for various pavement thicknesses were compared with pavement condition index (PCI) rating data obtained from a field application reflecting pavement performance of approximately 131,000 cycles of an 80 kN single-axle load. For this particular field application, it was found that, for cyclic loading, the required thickness of the pervious concrete layer was approximately 40 %–80 % higher compared with that for the static loading condition.

Pervious concrete is an alternative pavement material which may help reduce nonpoint source pollution problems. The porosity of pervious concrete is an important parameter used for both pavement and environmental design and is dependent on field placement techniques. It is recommended that porosity be tested on field-placed specimens. It has been noted that some of the concrete is knocked out while coring from field-placed samples which may affect the porosity. This paper researches a methodology for estimating the in situ porosity of pervious concrete from the porosities of cores taken from the field based on aggregate size, core size and porosity.