The gas is fed back over the calcium oxide.

气体被氧化钙反作。

Heating this chemical compound drives off carbon dioxide gas leaving calcium oxide.

加热这种化合物会驱除二氧化碳气体，留下氧化钙。

The essential ingredient in cement is calcium oxide, CaO.

水泥中的基本成分是氧化钙， CaO。

When water enters these tiny cracks, it hydrates the concrete’s calcium oxide.

当水进入这些微小的裂缝时，会水合混凝土中的氧化钙。

The heat is applied to limestone, to break up its principal constituent, calcium carbonate, into calcium oxide (cement's crucial ingredient) and CO2.

对灰施加热量，将其主要成分碳酸钙分解成氧化钙（水泥的关键成分）和二氧化碳。

The essential ingredient in cement is calcium oxide, CaO. We get that calcium oxide from limestone, which is mostly made of calcium carbonate: CaCO3.

水泥中的基本成分是氧化钙，CaO。 我们从灰中得到氧化钙， 主要由碳酸钙构成：CaCO3。

The researchers suspected the key was something called " hot mixing." It uses dry bits of calcium oxide, a mineral that's also called quicklime.

研究人员怀疑关键在于所谓的“热混合”。干燥的氧化钙，一种也称为生灰的矿物质。

Over time, some CO2 from the atmosphere drifts into all that cement in buildings and bridges, and reacts with the calcium oxide to form calcium carbonate again.

随着时间的推移，大气中的一些二氧化碳漂移到建筑物和桥梁的所有水泥中， 并与氧化钙反应再次形成碳酸钙。

Limestone is refined to produce calcium oxide, or quicklime, for cement, in a reaction known as calcination, which releases a lot of carbon in the form of CO2.

灰被提炼以生产于水泥的氧化钙或生灰， 在称为煅烧的反应中，该反应以 CO2 的形式释放大量碳。

The resulting calcium hydroxide reacts with carbon dioxide in the air, starting a process called autogenous healing, where microscopic calcium carbonate crystals form and gradually fill the gap.

生成的氢氧化钙与空气中的二氧化碳发生反应，开始一个称为自生愈合的过程，在此过程中会形成微小的碳酸钙晶体并逐渐填充间隙。

But in fact, most of the CO2 emissions come not from the heating, but from the breakdown of limestone, which is calcium carbonate, into calcium oxide and carbon dioxide, or CO2.

但事实上，大部分的二氧化碳排放不是来自加热，而是来自灰， 也就是碳酸钙， 分解成氧化钙和二氧化碳， 即二氧化碳。

It wasn't until 2004 that they found the cause of the problem was lime or calcium hydroxide, to give it its proper chemical name, which was being used in the construction of roads.

直到2004年，他们终于找到了这个问的根源是灰，或者叫一个专有化学名词，氢氧化钙，是一直被来建设公路的物质。