Show asphalt pavement better every year four Varlet 1 in common use asphalt is tho the oldest waterproof water proof adhesive known to man its uee use dated dates back beyond tho the mists which shroud prehistoric days unlike many baste basic materials science and invention bavo have not discovered any substitute tor for it and no synthetic asphalt Is producible commercially which compares either in price or in utility with the trio natural pro product duiLL asphalt ie Is used in roads in many ways wars but there are four broad divisions a generally by road engineers those these lour have been boon developed and year by year ac furi ther experiments and exper experience lenca be come available the types are improved until now it is generally conceded that tor for its purposes pur and aben properly laid asphalt has no superiors as a road juat erial the four our generally recognized types are L 1 asphalt macadaan ux tn in which broken stone has malted molted us m ahalt applied to it to petie penetrate the entire course with atone stone chipi to cover r the surface spaces and a seal coat of hot asphalt and stone chips 2 concrete made of an intimate mixture of asphalt and broken stone or gravel sand laid and compacted while hot into J t dinglo course sometimes finished with a seal coat 3 sheet asphalt con strutted ted in two courses the lower lowar of asphalt le concrete the top course of a mixture of asphalt and carefully graded mineral fluer 4 asphalt blocks made of concrete under heavy prea pre aure jaure and laid on a sand or mortar cushion like brick asphalt Is also used u a filler fitler for brick pavements mixed and sand to form a grout for stone block pavements and to fill the expansion joins in monolithic pavements of 0 cement |