Complex sentence: When cement or concrete are exposed to Mg 2 +, the neoformation of brucite, an expansive material, induces mechanical stress in the hardened cement paste and is responsible for the formation of cracks and fissures in concrete.
Split into simpler sentences: When cement or concrete are exposed to Mg 2 +. The neoformation of brucite, an expansive material, induces mechanical stress in the hardened cement paste and is responsible for the formation of cracks and fissures in concrete.