how does cement contribute to greenhouse gases ?
Because cement is derived from limestone. The limestone is quarried certain blocks of this limestone are heated in a lime kiln. The limestone (Calcium carbonate) is reduced to Quick Lime (Calcium Oxide) as a result of the heating of the rock in a kiln driving CO2 off in the process. However, when the cement is mixed with sand to make cement, the addition of water opens up the chemistry to change the calcium oxide to calcium hydroxide. Further than that, the calcium hydroxide, tries to re-incorporate the driven out CO2 back. At the time of hardening, the cement is a different chemical to what it had been at the time the cement was being mixed.
