Prefabricated concrete slabs used for construction tend to be of a size that can be easily carried on a truck. The truck has to reach the building site so there is a limit of about 2.5 m in one direction. If these are prefab slabs they look too large.

Such slabs usually have edge and corner damages from handling, incomplete mixing of the grout in the mould, etc. They also usually have some sort of system to keep them togeher, usually dowels or threaded steel with nuts. This locking system is located in holes in the concrete that are sealed off by the constructor. He is responsible for the construction and does not want anyone to tamper with the locking or rust/water to attack it. So, there usually are circular spots of 10-12 cm diameter arranged along the lower and upper edges, spaced practical distances. The openings are also used for lifting the slabs into place.

Then for the texture: I agree it is too large scale. Hint for texturing: you can use the y-component of the normal vectors (green channel output by the n-node) to identify horizontal spots where dust and dirt may gather.