Best practices for pervious concrete mix design and laboratory tests

Abstract 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.

摘要 透水混凝土（pervious concrete）可用于雨水管理，因其可使水流通过其相互连通的大孔隙（macropores）进入雨水系统或下方土体。然而，透水混凝土在大规模推广应用前，仍需完善相关标准，且其配合比设计以满足特定性能要求、击实方法及试验流程等诸多方面尚未完全明确。上述变量会显著影响该材料的功能与力学性能。本研究对配合比设计与试件制备工艺进行了评估。采用IBRACON配合比设计方法，针对目标孔隙率25%的要求，确定了配合比参数并计算得到相应密度。此外，设置了两种不同类型的试件（浇筑成型试件与钻芯试件）及两种击实方式（滚筒击实与普氏击实仪（Proctor hammer）击实）。所有试件的密度均控制为相同的计算密度。开展了多组试验以对比以下变量：密度、孔隙率、表面入渗率、渗透性与抗压强度。此外，还评估了砂浆封端与氯丁橡胶帽（neoprene-rubber caps）封端两种方式对透水混凝土抗压强度测试结果的影响。试验结果表明，浇筑成型试件的测试结果较钻芯试件更为一致。严格控制密度的设计方法可有效实现目标孔隙率，尤其适用于浇筑成型试件。滚筒击实会使试件顶面更为密实，导致钻芯试件的入渗率与渗透性下降。砂浆封端法的测试结果一致性优于其他封端方式。