CONCRETE PAVEMENTS, JAPAN

Cement concrete pavement slab thickness is considered, as well as the subbase courses of cement concrete pavements. Asphalt stabilized layers of 40 to 50 mm in thickness placed on top of subbase courses have improved the pavement durability. Joint designs have been considerably improved. Experimental pavements constructed with normal type Portland cement including some flyash and medium-heat type Portland cement, have demonstrated very high strength. Excellent performance has been observed with continuously reinforced concrete pavements subjected to heavy traffic for 7 years. Problems of concrete slab construction are identified as those relating to spreading and compacting the 300 mm thick slabs. Maximum performance of the slip form paver was 1,140 m per day. Surface regularity and the cracking ratio of pavements are measured ot decide procedures for maintenance and repair work and a chart for use in selecting standards is presented.