Microcement is a thin decorative finish, so movement in the base below can affect the surface. The important questions are where that movement comes from and how the project manages it.
Yes, microcement can crack. Common causes include movement or damage in the base, poorly treated joints, moisture, weak preparation or incorrect application. A well-planned system reduces the risk but cannot hide an active structural problem.
Where cracking usually begins. Movement can come from screeds, concrete slabs, board joints, tiled surfaces or connections between materials. An old crack may be stable or still moving. Finding the cause matters more than simply filling the line. Moisture, poor curing, dirt, weak bonding and incorrect application conditions can also cause failure. The full system should be checked, not only the visible finish.
Movement joints are not defects. A movement joint allows parts of a building to move separately. Covering it with a continuous finish does not stop that movement. It may only cause a crack to appear somewhere else. The project designer and system provider should agree how to handle these joints. A continuous look should not remove a joint that the building needs.
How risk is reduced. Reducing risk starts with checking the base and moisture, repairing defects, removing loose material and preparing the surface correctly. Reinforcement may be part of the system, but it cannot stop active structural movement. The materials, mixing, layer thickness, drying conditions, sanding, sealing and quality of application all affect the result. Good work still needs a sound base.
If a crack appears. First check whether the crack is stable or still moving, and whether moisture is involved. A quick surface repair may fail again if the cause is not fixed. The repair depends on the location, colour, texture, cause and installed system. Repairs are often possible, but the new area may not blend perfectly with the older finish.