Casting Compositions and Resulting Properties of Porous Concrete Substrates for Green Building and Hydroponic Plant Production

Bio-receptive porous concretes are different from regular concretes used in construction. Bio-receptive concretes allow for easy access to air and water while providing enough strength to hold the structure. Porous concrete is gaining more attention as a green building’s plant-growing substrate because of its extensive hydrological, mechanical, and biological properties. However, optimizing all three properties simultaneously is challenging, as casting focuses on one parameter and reduces the others. For example, if strength is prioritized during casting, porosity and permeability will be markedly reduced. Reaching a balance between these three parameters is required to make the final material acceptable for growing plants and holding the structure simultaneously. This study highlights how porous concrete casting elements, including aggregates, binders, water, water-to-binder ratio, and aggregate-to-binder ratio, critically affect the cast products by contributing to strength, porosity, permeability, durability, and plant growth capacity. The post-curing impact on porous concrete’s surface and internal framework is investigated, while casting and recycling of porous concrete are examined to ascertain the most advantageous alternatives. A comprehensive review is provided for all soilless crop producers and green building developers, as porous concrete would be a helpful substrate for hydroponic green roofs and green walls.