Question

why do we get hurt by falling on a concrete structure than on a sand track

Answer 1

A cement structure is a hard structure and it has many irregularities. This surface is formed from hardening of a clay like substance. Which do not change shape on force.
On the other hand a sand track is mostly porose and changes its order when it is in contact with a force which makes the impact effect low.
This is why we get hurt by falling on a concrete structure than on a sand track.

Answer 2

This surface is formed from hardening of a clay like substance. Which do not change shape on force. On the other hand a sand track is mostly porose and changes its order when it is in contact with a force which makes the impact effect low. This is why we hurt more on falling on a piece of concrete than a sand track.