Bitumen

原油是液體，瀝青是固體。柏油路看似堅固而且難以高溫熔解，箇中製作過程究竟是如何？

Asphalt, black or brown petroleum-like material that has a consistency varying from viscous liquid to glassy solid. It is obtained either as a residue from the distillation of petroleum or from natural deposits. Asphalt consists of compounds of hydrogen and carbon with minor proportions of nitrogen, sulfur, and oxygen. Natural asphalt is believed to be formed during an early stage in the breakdown of organic marine deposits into petroleum, characteristically contains minerals, while residual petroleum asphalt does not. 

www.britannica.com

glassy: dull

Asphalts are the varieties of naturally-occurring bitumen. Asphalts are also produced as a petroleum byproduct. Both substances are black and largely soluble in carbon disulphide. They are of variable consistency, ranging from highly viscous fluid to a solid. Asphalts occur with or without mineral matter.

Many types of asphalts occur as viscous impregnations in sand stones, silt-stones, and lime-stones. After treatment to remove water and volatile constituents, the asphalts are fused at 54–60 °C and contain about 83% carbon. Most of the asphalts are of marine origin and consist of the high-molecular weight compounds normally present in petroleum residue.

www.sciencedirect.com

If someone or something impregnates a thing with a substance, they make the substance spread through it and stay in it.

Sandstone is made of sand-sized particles. Siltstone is made of smaller particles. Silt is smaller than sand but larger than clay.