There are many materials that can substitute for concrete -- the problem is, they tend to cost more money, and aren't as versatile overall. Depending on usage, here are some proven substitutes, for --
Walls, floors and cellars/basements of buildings: Brick, steel, sandstone, wood.
Building foundations: You can use rubble to mostly substitute for concrete foundations, but some kind of mortar is still required, and this technique is not suitable for all soil types (read more). Wood and steel are options for deep foundations. Ancient huge structures (like the Egyptian pyramids) were built directly on bedrock.
Patios and driveways: A sand bed with closely laid bricks or other stones as the main surface.
Ponds or swimming pools: Plastic moulds for smaller ones. Larger pools can be made of fibre-glass, or with a steel, brick or even wooden frame with vinyl lining.
Curb stones: Granite, natural stone.
Roads, sidewalks, footpaths: Tarmac (asphalt), brick, cobblestones, dirt, gravel.
Bridges: Steel, brick.
Dams: Brick, stone, clay, earth fill.
Walls, floors and cellars/basements of buildings: Brick, steel, sandstone, wood.
Building foundations: You can use rubble to mostly substitute for concrete foundations, but some kind of mortar is still required, and this technique is not suitable for all soil types (read more). Wood and steel are options for deep foundations. Ancient huge structures (like the Egyptian pyramids) were built directly on bedrock.
Patios and driveways: A sand bed with closely laid bricks or other stones as the main surface.
Ponds or swimming pools: Plastic moulds for smaller ones. Larger pools can be made of fibre-glass, or with a steel, brick or even wooden frame with vinyl lining.
Curb stones: Granite, natural stone.
Roads, sidewalks, footpaths: Tarmac (asphalt), brick, cobblestones, dirt, gravel.
Bridges: Steel, brick.
Dams: Brick, stone, clay, earth fill.