- These coloured concrete building blocks from Adbri Masonry feature a smooth, flat surface texture. Work with this easy to use locking sytem to create an instant edge or retaining wall in your garden. This product will add instant impact to your garden project.Available in 4 colours Charcoal, Steel, Oatmeal, IvoryIdeal use: Can be used for garden steps, engineered walls, vertical retaining walls and residential landscaped wallsOther info: Various Sizes of product available, please call.