Here is a try for procedural concrete, basically it's only Noise Texture nodes mixed together (with Math/Add nodes or with MixRGB/Overlay nodes) to have various sizes and shapes of 3D bumps and grey spots:
File: 
Here is a try for procedural concrete, basically it's only Noise Texture nodes mixed together (with Math/Add nodes or with MixRGB/Overlay nodes) to have various sizes and shapes of 3D bumps and grey spots:
Here is a try for procedural concrete, basically it's only Noise Texture nodes mixed together (with Math/Add nodes or with MixRGB/Overlay nodes) to have various sizes and shapes of 3D bumps and grey spots:
File: