Abstract 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.
ABSTRACT 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.