The use of lightweight aggregate concrete in a 17m span bridge carrying a forest road over a river is described. The bridge deck consists of prestressed precast concrete inverted T-beams having in situ infilling and surfacing concrete. A lightweight coarse aggregate and natural sand were used for the precast concrete but only lightweight materials were used for the in situ concrete. Satisfactory strength and elastic properties were obtained with reductions in density of about 20 per cent for the precast and about 25 per cent for the in situ concrete. Measurements made on the structure show that time dependent strains are smaller than expected and are due mainly to creep of the concrete. Some seasonal variation due to shrinkage occurs but its effect is generally small, probably due to low moisture losses in the damp environment of the bridge. Loading tests on the bridge confirmed that its behaviour was as expected. (A)

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