MOLDING PROCEDURE FOR PERVIOUS CONCRETE SPECIMENS BY DENSITY CONTROL

Abstract

Pervious concrete (PC) is a special concrete with the main objective of surface runoff management, due to its hydraulic performance and infiltration capacity. Currently, the standards and guidelines (existing) do not adequately standardize the production process (molding procedures) under laboratory conditions. This fact hinders its correct application in the field since it does not have enough parameters to verify at least the compacting of the material (unit weight in the field). Compaction has a great influence on pervious concrete (PC) properties: porosity, permeability, and consequently, mechanical strength. Thus, this study aims to propose procedure standardization for molding cylindrical and prismatic specimens of PC (in laboratory conditions) using the unit weight like control parameter. The standard procedure chosen was the proctor hummer (2.5 kg and 305 mm of heigh fall), due to its ease and good results (low variability), both in the cylindrical specimens and in the prismatic ones where the point of application of the compaction blows was also defined. Finally, an experimental program was carried out to verify the hydraulic and mechanical properties of the produced PC, and the compliance of the standards was verified. Then it was verified that the proposed molding procedure produces PC within the standard parameters. Additionally, a control abacus related to the unit weight and the porosity (input data) was proposed to determine the number of blows to compact the PC, giving the opportunity to choose a porosity, and as a consequence, a prediction of the strength, facilitating the production process, depending on the final application of the material.

Keywords

• compaction
• pervious concrete
• unit weight
• permeability
• porosity