14 avr. 2009 - Nya - Chapter 15
Description:
Cement is made through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients. Common materials used in cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore.
Ajouté au bande de temps:
Hadyn, Bethany, Jocey, Natasha
Date:
