Academic literature on the topic 'Pervious surface layer'

Pervious concrete is an environmentally friendly paving material to reduce surface runoff in urban construction. However, due to low flexural strength and cracking susceptibility caused by the high porosity, pervious concrete is only used in low-volume traffic roadways and parking lots for current service. This study investigated the permeability, strength, and flexural performance of pervious concrete with different coarse aggregate size, geogrid position, and geogrid layer number. Test results indicate that the geogrid placed at an appropriate position in pervious concrete improved the permeability and compressive strength. Four-point bending tests were conducted in the laboratory to evaluate the flexural performance and toughness characteristics of pervious concrete beam. Meanwhile, this study also proposed a new evaluation method to distinguish the contribution of geogrids and concrete mixture to the flexural toughness of pervious concrete beam at the pre-peak and post-peak stages by two toughness indices. Test results indicate that geogrids improved the flexural strength, deformability, and energy absorption capability of pervious concrete beam. The geogrids placed at both one-third and two-thirds of the heights of pervious concrete beam resulted in the optimum flexural performance. Besides, the small size (5–10 mm) aggregates were conducive to providing high flexural strength for the geogrid-reinforced pervious concrete beam, while the large size (10–15 mm) aggregates played a significant role in obtaining noteworthy post-cracking performance.

This paper deals with the possibility of the improvement of pervious concrete properties by incorporation of different types of fibres and studies the effect of short duration vibration of pervious concrete properties in comparison with compaction with wooden lath and hammer. Ten mixtures of pervious concrete were prepared, five of which were compacted with wooden lath and hammer and five by short duration vibration. Density, porosity, permeability and mechanical properties were tested for in hardened pervious concrete specimens. It was concluded that mixtures compacted by short duration vibration had better mechanical properties due to the formation of a viscous layer at the contact surface between the aggregate grain and the cement matrix during the compaction, as well as pore-related properties. The addition of fibres negatively affected porosity and permeability but generally improved mechanical properties of concrete. The positive effect of fibre addition was more emphasised in cases of vibrated mixtures.

This paper presents an analytical investigation on the excess pore-fluid pressure in a finite seabed layer by taking into account the influence of a compressible pore fluid. The seabed layer is modeled as a poroelastic layer saturated with a compressible pore fluid and resting on a rough, rigid impermeable base. The surface of the poroelastic seabed layer is either completely pervious or completely impervious, and subjected to a normal surface traction induced by offshore structures. The paper presents analytical and numerical results to illustrate the time-dependent behaviour of excess pore pressure in the poroelastic seabed. The results demonstrate that the presence of a compressible pore fluid reduces the generation of excess pore pressure in the poroelastic seabed layer. Key words : excess pore pressure, poroelastic seabed layer, soil consolidation, compressible pore fluid, integral transforms.

The urban water balance can be attenuated to the natural by water-permeable pavements (WPPs). Furthermore, WPPs have a 16% higher evaporation rate than impermeable pavements, which can lead to a better urban climate. Evaporation rates from pavements are influenced by the pavement surface and by the deeper layers. By a compared evaporation measurement between different WPP designs, the grain size distribution of the sub-base shows no influence on the evaporation rates in a significant way. On the contrary, a sub-base made of a twin-layer decreases the evaporation by 16% compared to a homogeneous sub-base. By a change in the colour of the paving stone, 19% higher evaporation rates could be achieved. A further comparison shows that the transpiration-effect of the grass in grass pavers increases the evaporation rates more than threefold to pervious concrete pavements. These high evapotranspiration rates can not be achieved with a pervious concrete paving stone. In spite of this, the broad field of application of the pervious concrete paving stone increases the importance in regard to the urban climate.

Decreasing the emissions of CO2 that come from vehicle exhaust, especially in car parking and tunnels, is so vital. CO2 emissions cause corrosion to a reinforcement of concrete. Thus, there is a need to provide a layer that protects the reinforcement from the reach of this harmful gas. This work goals to investigate the efficiency of using board units from Pozzolime concrete and pervious concrete to sequestrate CO2 from the environment and then to convert it into calcium carbonate inside the concrete. The units have dimensions of (200×400×40±5). All specimens were cured in a water tank after about 48 hours after casting. Then paint the sample from all surfaces (three layers) excluding the top surface. The pervious concrete and Pozzolime specimens, at age of 28 days, were put in the chamber, then the gas was supplied to the chamber with concentrations of 15%, 25%, and 50 %, for 24 hours. The efficiency was evaluated through carbonation depth, CO2-uptake, and weight change. The results showed that the maximum CO2 uptake was recorded at the age of 28 days for Pozzolime concrete when exposed to 50% of CO2 concentration.

The current approach to stormwater management should focus on dealing with water on its source. The Sustainable Urban Drainage Systems (SuDS) promotes runoff peak flow and volume attenuation, load removal while providing amenites and biodiversities but can be difficult to apply in developed urban centers. An infiltration-exfiltration system (IES) placed on road gutters can function on receiving runoff from roads and directing them to the sewers system reducing peak flow and volume. This research follows up a full-scale test of an IES installed in São Paulo, Brazil. The IES has 49 × 1880 m dimension and a cross-section of 49 × 30 cm with a pervious concrete surface layer. The pervious concrete showed mechanical results acceptable for a low vehicular traffic and infiltration rate that allows water infiltration. Rainfall-runoff modeling showed that the proposed IES had a low effect on runoff peak flow and volume attenuation. A deeper gravel layers depth and outlet flow restrictor would improve performance. The proposed IES function on avoid ponding, promoting water treatment, and reducing inlet maintenance.

Porous pavements infiltrated with stormwater are faced with clogging problems: runoff particles seep and clog the pervious surface layer of these structures. Clogging material samples (in the form of sludge) have been collected in cleaning operations on the pervious asphalt. This study aims at characterizing these materials, particle size distribution, heavy metal contents by particle size, and studying interactions between metals and particles. A sequential extraction procedure proposed by the experts of the Community Bureau of Reference (B.C.R.) was applied to provide information about heavy metal distribution on particles and to evaluate interaction strength, and consequently potential metal mobility when chemical variations occurred in the environment. Mainly made up of sand, the materials are polluted with lead, copper, zinc and cadmium. The concentrations appeared to be linked with road traffic intensity. The heavy metal contents by particle size showed that the finer are the particles, the higher are the heavy metal concentrations. Heavy metals were found potentially labile; metals contents in the residual fraction (mineral fraction) represented less than 20 % of the total concentration. Cadmium and zinc were apparently more labile than lead and copper.

Green infrastructure has a role to play in climate change adaptation strategies in cities. Alternative urban spaces should be designed considering new requirements in terms of urban microclimate and thermal comfort. Pervious pavements such as green parking lots can contribute to this goal through solar evaporative cooling. However, the cooling benefits of such systems remain under debate during dry and warm periods. The aim of this study was to compare experimentally the thermal behavior of different parking lot types (PLTs) with vegetated urban soil. Four parking lots were instrumented, with temperature probes buried at different depths. Underground temperatures were measured during summer 2019, and the hottest days of the period were analyzed. Results show that the less mineral used in the surface coating, the less it warms up. The temperature difference at the upper layer can reach 10 °C between mineral and non-mineral PLTs. PLTs can be grouped into three types: (i) high surface temperature during daytime and nighttime, important heat transfer toward the sublayers, and low time shift (asphalt system); (ii) high (resp. low) surface temperature during daytime (resp. nighttime), weak heat transfer toward the sublayers, and important time shift (paved stone system); and (iii) low surface temperature during daytime and nighttime, weak heat transfer toward the sublayers, and important time shift (vegetation and substrate system, wood chips system, vegetated urban soil). The results of this study underline that pervious pavements demonstrate thermal benefits under warm and dry summer conditions compared to conventional parking lot solutions. The results also indicate that the hygrothermal properties of urban materials are crucial for urban heat island mitigation.

Urban evaporation, as an essential part of local water vapor resources in urban areas, has often been underestimated. One possible reason is that the evaporation of urban hardened surfaces is seldom considered and poorly understood in urban evaporation estimation. This study focused on the mechanisms and calculation of evaporation on hardened surfaces in urban areas. Experimental monitoring was used to monitor the processes and characteristics of evaporation on hardened surfaces. Mathematical models based on water quantity constraints were built to calculate evaporation of hardened surfaces. The results showed that: The interception abilities for rainwater and rainfall days of impervious hardened surfaces determine their evaporated water amount, which means no water, no evaporation for the impervious surfaces. The greater evaporation of artificial sprinkling on roads happened in fewer days of rainfall and frost. The evaporation of pervious hardened ground is continuous compared to the impervious surface. Its soil moisture in the sub-layer of permeable concrete decreases periodically with a period of one day. The evaporation of hardened surfaces occupies 16–29% of the total amount of evaporation in the built-up areas in cities. Therefore, the hardened surface evaporation has great significance on the urban hydrological cycle and urban water balance.

Pervious Paving (Paving Berpori) adalah material konstruksi yang terbuat dari semen, air, agregat dan bahan campuran lainnya. Paving berpori dapat diapilkasikan pada trotoar, area bermain dan jalan perumahan. Dengan menggunakan paving berpori air akan langsung meresap, sehingga akan mencegah adanya genangan air pada lapis permukaan paving. Metode penelitian yang digunakan adalah menggunakan AAPA (Australian Asphalt Pavement Association) dimana dilakukan sistem Trial Eror. Campuran yang digunakan adalah 1:4, dengan menggunakan gradasi terbuka. Kuat tekan yang di rencanakan yaitu 18,00 MPa, masuk dalam kategori mutu B untuk tempat parkir mobil, pejalan kaki dan taman kota. Campuran paving menggunakan abu sekam padi sebagai reduksi semen dengan persentase 0%, 10%, 20% dan 30%. Pelaksanaan pekerjaan dimulai dari pengambilan bahan baku, pengujian material, perencanaan komposisi dan pembuatan benda uji dengan ukuran P = 21 cm, L = 11,5 cm dan T = 6 cm. Uji kuat tekan dilakukan untuk mengetahui pengaruh abu sekam sebagai bahan reduksi semen pada Paving Berpori. Nilai kuat tekan yang didapatkan akan menjadi input pada program Matlab untuk mendapatkan pemodelan Persamaan Empiris dengan ARTIFICIAL NEURAL NETWORK (ANN) sehingga didapatkan nilai kuat tekan dari berbagai komposisi penambahan bahan abu sekam. Dari hasil penelitian didapatkan persentase tertinggi dicapai pada tambahan abu sekam 30%.Kata kunci : Abu sekam, Artificial Neural Network (ANN), Pervious Paving, Kuat tekan, Persamaan EmpirisPervious Paving is a construction material made from cement, water, aggregate and other materials. Pervious paving can be applied to right on sidewalks, play ground and residential roads. By using Pervious Paving, the water will absorb quickly, so it will prevent the puddles on the surface layer. AAPA (Australian Asphalt Pavement Association) is the reserach methode which we used with Trial and Eror. The mixture of ingredients is 1: 4 with the open gradation. The compressive strength designed is 18 MPa, which is in category B for parking car, pedestrian and city park. Paving mixture consisted of rice husk ash as cement reduction with a percentage of 0%, 10%, 20% and 30%. The work starting from the taking of raw materials, material testing, composition planning and the making of specimens with sizes P = 21 cm, L = 11.5 cm and T = 6 cm. The compressive strength test was conducted to determine the effect of husk ash addition. The compressive strength will be input to the Matlab program to obtain the Empirical Equation modelling with ARTIFICIAL NEURAL NETWORK (ANN). Based on the results of the study, the highest percentage was achieved in the mixture with an addition of 30% rice husk ash.Keywords: Rice husk ash, Artificial Neural Network (ANN), Pervious Paving, Compressive strength, Empirical Equation

O emprego de pavimentos permeáveis tem se tornado cada vez mais necessário como medida compensatória para amortecer as vazões de pico e atenuar os impactos gerados pelas chuvas torrenciais em áreas altamente urbanizadas. Dentre os materiais convencionalmente adotados como revestimento permeável no contexto nacional destacam-se os blocos de concreto intertravados (BCI) e o asfalto poroso. No entanto, internacionalmente, existem materiais alternativos que podem apresentar permeabilidade igual ou até mesmo superior. Sob esse prisma, convém destacar o uso dos blocos de concreto articulados (BCA), recentemente adotados nos Estados Unidos e na Coréia do Sul, cuja capacidade de infiltração vem mostrando-se bastante promissora. Diferentemente dos blocos intertravados, os BCA foram projetados para trabalhar em conjunto, já que são interconectados por meio do encaixe das articulações unidirecionais de cada peça, sobrepostas umas às outras, dispensando assim o uso de material de rejunte, o que por sua vez aumenta a permeabilidade do revestimento. Contudo, embora o desempenho hidráulico aparente ser eficaz, questiona-se se o pavimento de blocos de concreto articulados (PBCA) comporta-se de forma igualmente satisfatória em termos estruturais. Nesse sentido, visando avaliar o desempenho estrutural e hidráulico de um pavimento permeável de BCA, foi construída uma pista experimental (20 x 5 m) no Campus da USP, adotando-se dois tipos de base, uma de agregado reciclado (RCD) e outra de agregado natural (brita 1). Na análise estrutural utilizaram-se como parâmetros de avaliação as deflexões máximas obtidas via FWD (Falling Weight Deflectometer), a eficiência de transferência de carga (LTE - Load Transfer Efficiency) e por fim, os módulos de resiliência retroanalisados para cada camada. Ademais, a pesquisa ainda avaliou a influência da presença de fissuras ou trincas nos blocos no desempenho estrutural do pavimento, já que acabaram tornando-se recorrentes em ambas as seções avaliadas. Já na avaliação hidráulica, monitorou-se a taxa de infiltração in situ ao longo de quase vinte meses. Complementarmente, foram realizadas ainda avaliações laboratoriais dos materiais empregados e funcionais do pavimento. A análise estrutural indicou que o sentido articulado do BCA obteve respostas estruturais nitidamente melhores que o sentido não articulado em termos de módulo de resiliência, deflexões máximas e LTE, evidenciando que de fato as articulações conferem intertravamento ao pavimento, próximo ao propiciado pela areia de rejunte no BCI. A base de RCD por apresentar uma distribuição granulométrica mais bem distribuída do que a brita 1, também obteve melhores resultados. Já a presença de trincas ou fissuras nos blocos não acarretou comprometimento no desempenho estrutural da pista experimental, devido ao baixo grau de severidade da maioria das patologias encontradas, como atestou o levantamento funcional, cuja classificação indicou um pavimento em boas condições de serventia. No que diz respeito ao desempenho hidráulico, o pavimento apresentou um desempenho adequado em termos de capacidade de infiltração. Apesar da perda progressiva estimada em 20% ao ano, as taxas de infiltração in situ mantiveram-se acima de 10-3 m/s em todos os ensaios realizados, sendo, portanto, superior à maioria dos revestimentos permeáveis tradicionalmente utilizados como os blocos intertravados e a camada porosa de atrito, conforme descritos pela literatura.
Pervious pavements have become increasingly fundamental as a compensatory measure to attenuate peak flows and to mitigate the impacts generated by torrential storm water in highly urbanized areas. Among the usual materials applied in permeable surface layers, it is possible to highlight the interlocking concrete blocks (ICB) and the porous asphalt. However, internationally, there are alternative materials that are able to present a higher permeability. In this sense, the use of articulated concrete blocks (ACB) needs to be stressed. Recently adopted in United States of America and South Korea, ACB has presented promising infiltration rates. Unlike the ICB, the ACB was designed to work as an integrated framework due to the presence of articulated joints in one of the block directions, which allows discarding the jointing sand and as result, increases water infiltration. Nevertheless, although the pavement hydraulic performance seems to be successful, there are some doubts about the structural behavior. Thereby, aiming at evaluating the hydraulic and structural performance of an unidirectionally articulated concrete block pavement, a pavement experimental section (20 x 5 meters) was constructed at the University of São Paulo Campus. Two types of different bases were applied, namely recycled concrete aggregate (RCA) and natural aggregate. The structural assessment took into account the maximum deflection measurements, the load transfer efficiency (LTE) and the backcalculated elastic moduli of each layer. In addition, this work also evaluated the structural influence caused by the presence of damaged pavers, since it became a recurring problem. Regarding the hydraulic evaluation, the surface infiltration rate was monitored over twenty months after the pavement construction. Furthermore, functional and laboratorial analyses were carried out in order to check the structure serviceability level. The structural results indicated clearly that the articulated block side had better performance than the non-articulated block side in terms of elastic moduli, maximum deflections measurements and LTE, confirming the interlocking efficiency generated by the block shape, comparable to that one provided by the jointing sand in ICB. As the recycled aggregate was characterized by a more well graded particle size distribution than the natural aggregate, the RCA base also presented better structural responses. The presence of damaged blocks did not compromise the pavement structural performance, since the degree of severity was low, as verified by the functional evaluation, which showed a pavement in good conditions. Finally, concerning the hydraulic results, the pavement presented a high infiltration capacity. Even though an infiltration loss of about 20% per year has been detected, the infiltration rate remained greater than 10-3 m/s for all tests performed, being considerably higher than those found in pavements built with both interlocking concrete blocks and with porous asphalt, as reported in the literature.

碩士
國立臺灣海洋大學
河海工程學系
106
In this study, we focuses on the pervious concrete surface layer pavement material, and the goal is to find appropriate mixtures for making high strength pervious concrete syrafce layer pavement material. The water-to-cement ratio and the aggregate size was fixed, and two different superplasticizers (including sulfonated naphthalene-formaldehyde polymer and polycarboxylate), percentages of voids filled by binder and compacting or not were considered as experimental variables. The following experiments were performed to investigate the properties of pervious concrete surface layer pavement materials: slump test, water permeability coefficient test, connected pore volume test, compressive strength test, bending strength test, British pendulum test and abrasion resistance capability test. Results show that among the mixtures we study, one of them can satisfy the heavy traffic loading requirements for high performance pervious pavement in Taiwan as the water permeability coefficient reaches 0.104 cm/sec and 28-d compressive strength is 30.10 MPa (using polycarboxylate). And one of them can satisfy the medium and small traffic loading requirements as the water permeability coefficient reaches 0.561cm/sec and 28-d compressive strength is 24.26 MPa (using polycarboxylate). Also, mixture to satisfy the pavement loading requirements for bicycle and pedestrain can be found and its water permeability coefficient can reach 1.157 cm/sec while its 28-d compressive strength is 22.07 MPa (using sulfonated naphthalene-formaldehyde polymer). Among all mixtures we study, the values of British pendulum number (BPN) do not vary much. The average value of BPN values as well as the minimum BPN value satisfy the all requirements for pavements under various conditions in United Kingdom. In addition, the abrasion depth is related to compressive strength. That is when the abrasion depth is deeper, the compressive strength is lower.