Multi-modified effects of varying admixtures on the mechanical properties of pervious concrete based on optimum design of gradation and cement-aggregate ratio

The mechanical properties of pervious cement concrete (PCC) could be significantly enhanced through adding admixtures. This study was to investigate the multi-modified effects of different types of admixtures based on optimum design of gradation and cement-aggregate ratio (C/A). The influence of gradation and C/A on the compressive strength and porosity of PCC were firstly studied. Then a further optimum C/A for a constant gradation of aggregates with adhesion mixtures including the water-reducing agent (WA) and reinforcing agent (RA) was conducted. More types of admixtures were further added to enhance the compressive strength. In addition, these single admixtures added into the graded PCC were also comparatively explored. The results on the compressive strength revealed that 1) adding admixtures (single or multiple) was in general more effective than increasing C/A or the content of fine aggregate, while increasing C/A was slight better than increasing the fine aggregate; 2) The two adhesion admixtures wrapped more cement pastes without the phenomenon of cement segregation, which resulted in a higher optimum C/A and extra fillers from the surplus cement; 3) The multi-modified effect by three physical fibers were all excellent compared to those of two fine solid wastes, based on the two adhesion admixtures; 4) There existed fairly good relationships between apparent density and compressive strength of the graded PCC both with these single and multiple admixtures. (C) 2019 Elsevier Ltd. All rights reserved.