Hydraulic conductivity and strength of pervious concrete for deep trench drains

Pervious concrete for deep trench drains, used to stabilise slopes, must meet many requirements, namely, adequate hydraulic conductivity, adequate shear strength a few days after pouring, capacity to act as a protective filter for soils in which the drain is installed, good resistance to clogging and adequate residual hydraulic conductivity. In current engineering practice, the composition of pervious concrete for drains is improperly selected according to criteria used for no-fines concrete for road pavements. To detect more suitable and specific criteria, a laboratory investigation has been conducted aimed at identifying the composition and the properties of pervious concrete satisfying the above requirements. The results of these tests are reported in the paper. They show that it is possible to devise mix-designs of pervious concrete that satisfy all the abovementioned requirements. Special attention has been paid to the hydraulic conductivity and the strength and to their relationship to the water/cement and the aggregate/cement ratios and to the granulometric composition of the aggregates.