Hydrated cement paste shrinks mainly because it loses dampness from its particularly modest pores. Because the humidity is misplaced in these tiny pores, the surface pressure from the remaining h2o has a tendency to pull the pores jointly which leads to a loss of volume eventually. Curing also impacts cracking. https://www.tjcyindustrialchem.com/news/cement-additives-and-concrete-admixtures-key-differences.html