Kelio istorija. Rišamosios kelių tiesimo medžiagos

Abstract

The most significant result of this push was the development of asphalt roads. There is much confusion over the use in English language of the words bitume and asphalt. Roadmaking use of asphalt required advanced technology and did not occur until the nineteenth century. In nature asphalt occurs when bitume mixes with the local rock formation. To distinguish this asphalt from the manufactured product, we call it native asphalt. In Europe native asphalt quarries were found on the Creek islands and in Albania at about the time of Christ. The Romans worked mines in Swiss and in France. Spanish writers in 1526 first mentioned the Trinidad Pitch Lake - 60 ha pit of native asphalt with very high 40 percent bitume content.. In 1595 Sir Walter Raleigh used this material for caulking his ships. Geargius Agricola, in his book in 1556 described one of the number of methods then in use for removing of bitumen from native asphalt. Mastic was first used to make a road pavement in 1796, when it was employed as a waterproof surface on the timber deck of the 72 m span iron bridge in England. It incidentally provided a runnig surface for traffic. Mastic had the potential to meet the needs of footpaths for smooth and clean-able walking surface. The mastics proved highly effective in waterproofing decis and footways, but were often unacceptably slippery. This was overcome by addinf sand to the surface in 1824. As experience with footpath construction increased, it was observed that when the sand used to roughen the surface accidentally penetrated into hot mixture, it significantly stiffened the finished mastic layer. After 1850 it became common to add less expensive sand during mixing to produce a cheaper material.