Evaluation of mechanical properties of silica fume mixed with pervious concrete pavement

Environmental problems including urban heat islands, waterlogging, pollution and catastrophic climates occur frequently and on a worldwide scale. Pervious concrete pavement (PCP) has some benefits in fighting against such environmental problems as it enables greater rainwater drainage, thereby reducing the urban heat island effect, fostering ecological balance in cities and resolving urban flooding. However, the porousness reduces its overall strength and the use of some additives becomes inevitable. This study uses silica fume as an additive to the PCP to improve its strength and aims to investigate how silica fumes affect the characteristics of environmentally friendly pervious concrete. The silica fume is added to the PCP matrix in three different ratios (2, 4 and 6%), and compressive strength, flexural strength and split tensile strengths of silica fume-modified PCPs are evaluated. Further, porosity and permeability are also investigated as these are the key parameters to maintain water percolation. The test results confirmed that adding silica fume improved the strength of PCP specimens. Compressive strength increases about 2.2 times and 3 times when 4 and 6% silica fume are added to the mix. Similarly, split tensile strength and flexural strength have increased by 9–10%, 25–36% and 39–49% when 2, 4 and 6% silica fume are added to the mix. However, there was no notable change in the porosity and permeability of the PCP mixes and the values range within ± 5%.