After the Middle Ages the Roman Empire, the Middle Ages began. In the meantime asphalt, asphalt road asphalt lost its former glory. People use asphalt experience gained in the last millennium lost almost exhausted Shandong asphalt, until the eighteenth century, people began to re-start learning to use the pitch. In the year 1000 the Arabs began to extract bitumen (Bitumen) from natural bitumen (Naturasphalt) in. The method is heating natural asphalt (Naturasphalt) until the bitumen (Bitumen) from precipitation. Modern Eirini d'Eyriny written doctoral dissertation in 1721 on the cover 1712 asphalt cheap Greek physician Eirini d'Eyriny Swiss Val de Travers discovered huge reserves of bitumen mine. At first he just interested in the medical use of asphalt. However, due to the characteristics of the asphalt as an excellent asphalt properties of engineering materials, he eventually wrote his thesis in 1721 "on the asphalt of the doctoral thesis" (Dissertation sur L'Asphalte ov Ciment Naturel) and begin to lay the foundation for the study of modern asphalt technology. After three hundred years (1712 --1986 years), I do not know how much is located in Val de Travers asphalt by the total length of over 100 kilometers of the intricate maze of mine tunnels, they are mined and sold around the world. Asphalt Stock | Three-ping Chemical | asphalt provided by the Jinan Chemical Co., Ltd. three levels. Jinan three ping Chemical Co. (www.sanpinghuagong.com) quality of service and products, continue to receive the recognition and trust of new and old customers and the industry. Our company is a certified member of the whole alliance network operators, business alliance customer service icon on the page, you can talk directly with our customer service staff, to our future cooperation happy!