The design, construction and early performance of a 1.6 km long continuously reinforced concrete (CRC) overlay on Trunk Road A3 at Horndean are described. The existing road was a 200 mm thick concrete pavement constructed in 1946-7. Most of the slabs were reinforced and a section of the road had been used as an experiment investigating the relationship between reinforcement weight and joint spacing. Because of faulting and spalling at transverse joints and a reversal of the traffic flow, the riding quality was unacceptable. For these reasons and also to extend the life of the road a widening and overlay were necessary. Two contiguous section of CRC overlay were laid, one 110 mm thick and the other 130 mm thick. Reinforcement weighing 7.05 kg per square metre was used throughout both sections giving longitudinal steel percentages of 0.71 for the 110 mm thickness and 0.60 for the 130 mm thickness. Wide-flange beam joints were installed at the ends of the CRC overlay. Construction was by slip-form paver which laid the 9m wide slab in one operation. A control section consisting of a 0.2 km length of 100 mm thick hot rolled asphalt was also laid. The CRC overlay was constructed in September 1979 and the road was reopened to traffic in October 1979. Cracking occurred very early in the life of the section and there is closely-spaced cracking above the transverse joints in the old pavement. Reflective cracking has occurred above the longitudinal joint of the old pavement and also over the joint between the widening and the old slabs. A 5m length was replaced during the maintenance period as a trial of repair techniques and many cracks have been sealed by a "banding" process. The experiment is being inspected at regular intervals.(A)

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