![porus concrete porus concrete](https://image.made-in-china.com/44f3j00GjSTEswqZcoY/Porous-Concrete-Additives-High-Strength-Concrete-Intensifier-Permeable-Concrete-Hardener.jpg)
However, the increase in the metakaolin amount of 10% can be considered excess, where the mortar tended to cover the aggregates more and permeability started to decrease, showing the same results as the Control mixture. In this scenario, replacing 5% of cement with metakaolin doubled the permeability. In the case of replacing part of the cement with metakaolin (95C-5MK and 90C-10MK), results demonstrated that the porosity increased and permeability resulted. However, considering the promising results, an adjustment in the mix design of the geopolymer mixtures could increase their mechanical properties without negatively affecting the porosity, making these materials a suitable alternative to traditional porous cement concrete, and a solution to be used in urban pavements. Geopolymer mixtures can achieve permeability significantly higher than the traditional porous concrete, but this decreases their indirect tensile strength.
![porus concrete porus concrete](https://sightline-wpengine.netdna-ssl.com/wp-content/uploads/2011/12/Pervious-concrete.jpg)
Results demonstrated that replacing 5% of cement with metakaolin can increase both permeability and indirect tensile strength. A deep analysis was proposed for the evaluation of the mechanical and volumetric properties of the mixtures. Two sets of mixtures were analyzed to evaluate the Porous Concrete Design (PCD) methodology for porous concrete mixtures with alternative materials. Starting from a partial substitution of Portland cement with metakaolin, experimental geopolymer concretes were produced with metakaolin and waste basalt powder according to several dosages. In the present investigation, the addition of alternative materials to minimize the use of cement in porous concrete pavements is evaluated. In this context, the implementation of sustainable urban drainage systems has grown, especially with porous pavements, with the intention to reduce water and environmental impacts. Alternative materials to replace cement in pavements have recently been widely studied with the purpose of decreasing the environmental impacts that the construction industry generates.